Test Bank For ECGs Made Easy, 6th - 2023 All Chapters Barbara Aehlert

TEST BANK ECGs MADE EASY 6TH EDITION | AEHLERT

TEST BANK

ECGs Made Easy 6th Edition by Barbara Aehlert Test Bank Table of Contents: Chapter 1. Anatomy & Physiology Chapter 2. Basic Electrophysiology Chapter 3. Sinus Mechanisms Chapter 4. Atrial Rhythms Chapter 5. Junctional Rhythms Chapter 6. Ventricular Rhythms Chapter 7. Atrioventricular Blocks Chapter 8. Pacemaker Rhythms Chapter 9. Introduction to the 12-Lead ECG Chapter 10. Post-Test

Chapter 01: Anatomy and Physiology Aehlert: ECGs Made Easy, 6th Edition MULTIPLE CHOICE 1. The apex of the heart is formed by the a. tip of the left ventricle b. tip of the right atrium c. right atrium and right ventricle d. left atrium and left ventricle

.

ANS: A

The heart’s apex, or lower portion, is formed by the tip of the left ventricle. The apex lies just above the diaphragm, between the fifth and sixth ribs, in the midclavicular line.

OBJ: Identify the surfaces of the heart.

2. The left atrium receives blood from the a. pulmonary veins b. aorta c. pulmonary arteries d. inferior vena cava

.

ANS: A

The left atrium receives freshly oxygenated blood from the lungs via the right and left pulmonary veins.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

3. The anterior surface of the heart consists primarily of the a. left atrium b. right atrium c. left ventricle d. right ventricle

.

ANS: D

The front (anterior) surface of the heart lies behind the sternum and costal cartilages. It is formed by portions of the right atrium and the left and right ventricles. However, because the heart is tilted slightly toward the left in the chest, the right ventricle is the area of the heart that lies most directly behind the sternum.

OBJ: Identify the surfaces of the heart.

4. Blood pressure is determined by multiplied by a. stroke volume; heart rate b. heart rate; cardiac output c. cardiac output; peripheral vascular resistance d. stroke volume; peripheral vascular resistance

.

ANS: C

Blood pressure is equal to cardiac output multiplied by peripheral vascular resistance.

OBJ: Identify and explain the components of blood pressure and cardiac output.

5. The right atrium receives venous blood from the head, neck, and thorax via the

the remainder of the body via the , and from the heart via the a. coronary sinus; superior vena cava; inferior vena cava b. superior vena cava; coronary sinus; inferior vena cava c. inferior vena cava; superior vena cava; coronary sinus d. superior vena cava; inferior vena cava; coronary sinus

, from

.

ANS: D

The right atrium receives blood low in oxygen from the superior vena cava, which carries blood from the head and upper extremities; the inferior vena cava, which carries blood from the lower body; and the coronary sinus, which is the largest vein that drains the heart.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

6. The heart is divided into a. two; four b. three; two c. four; two d. four; three

chambers but functions as a

-sided pump.

ANS: C

The heart has four chambers: two atria and two ventricles. The right and left sides of the heart are separated by an internal wall of connective tissue called a septum. The interatrial septum separates the right and left atria. The interventricular septum separates the right and left ventricles. The septa separate the heart into two functional pumps. The right atrium and right ventricle make up one pump. The left atrium and left ventricle make up the other.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

7. Stimulation of alpha1 receptors results in a. increased heart rate b. peripheral vasoconstriction c. constriction of bronchial smooth muscle d. increased force of myocardial contraction

.

ANS: B

Alpha1 receptors are found in the eyes, blood vessels, bladder, and male reproductive organs.

Stimulation of alpha1 receptor sites results in constriction.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

8. Which side of the heart is a low-pressure system that pumps venous blood to the lungs? a. Left b. Right ANS: B

The job of the right side of the heart is to pump unoxygenated blood to and through the lungs to the left side of the heart. This is called the pulmonary circulation. The right side of the heart is a low-pressure system.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

9. Which side of the heart is a high-pressure system that pumps arterial blood to the systemic

circulation? a. Left b. Right ANS: A

The left side of the heart is a high-pressure pump. The job of the left heart is to receive oxygenated blood and pump it out to the rest of the body. This is called the systemic circulation. The left ventricle is a high-pressure chamber. Its wall is much thicker than the right ventricle (the right ventricle is 3 to 5 mm thick; the left ventricle is 13 to 15 mm thick).

This is because the left ventricle must overcome a lot of pressure and resistance from the arteries and contract forcefully in order to pump blood out to the body.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

10. The thick, muscular middle layer of the heart wall that contains the atrial and ventricular

muscle fibers necessary for contraction is the a. epicardium b. pericardium c. myocardium d. endocardium

.

ANS: C

The myocardium (middle layer) is a thick, muscular layer that consists of cardiac muscle fibers (cells) responsible for the pumping action of the heart.

OBJ: Describe the structure and function of the coverings of the heart.

11. Blood flows from the right atrium through the a. mitral b. aortic c. pulmonic d. tricuspid

valve into the right ventricle.

ANS: D

Blood flows from the right atrium through the tricuspid valve into the right ventricle.

OBJ: Beginning with the right atrium, describe blood flow through the normal heart and lungs to the systemic circulation.

12. Rapid ejection of blood from the ventricular chambers of the heart occurs because the

and valves open. pulmonic; aortic tricuspid; mitral pulmonic; mitral tricuspid; aortic

a. b. c. d.

ANS: A

When the ventricles contract, the pulmonic and aortic valves open, allowing blood to flow out of the ventricles.

OBJ: Name and identify the location of the atrioventricular (AV) and semilunar (SL) valves.

13. The base of the heart is found at approximately the level of the a. first b. second c. fourth d. fifth and sixth

rib(s).

ANS: B

The base of the heart is its upper portion and is formed mainly by the left atrium, with a small amount of right atrium. It lies at approximately the level of the second rib, immediately in front of the esophagus and descending aorta.

OBJ: Identify the surfaces of the heart.

14. Which of the following are semilunar valves? a. Aortic and pulmonic b. Aortic and tricuspid c. Pulmonic and mitral d. Tricuspid and mitral ANS: A

The pulmonic and aortic valves are semilunar (SL) valves. The semilunar valves prevent backflow of blood from the aorta and pulmonary arteries into the ventricles.

OBJ: Name and identify the location of the atrioventricular (AV) and semilunar (SL) valves.

15. Blood leaves the left ventricle through the

valve to the aorta and its branches and is

distributed throughout the body. a. mitral b. aortic c. pulmonic d. tricuspid ANS: B

When the left ventricle contracts, freshly oxygenated blood flows through the aortic valve into the aorta and out to the body.

OBJ: Beginning with the right atrium, describe blood flow through the normal heart and lungs to the systemic circulation.

16. Blood flows from the left atrium through the a. mitral b. aortic c. pulmonic d. tricuspid

valve into the left ventricle.

ANS: A

Blood flows from the left atrium through the mitral (bicuspid) valve into the left ventricle.

OBJ: Beginning with the right atrium, describe blood flow through the normal heart and lungs to the systemic circulation.

17. The right ventricle expels blood through the a. mitral b. aortic c. pulmonic d. tricuspid

valve into the pulmonary trunk.

ANS: C

The right ventricle expels the blood through the pulmonic valve into the pulmonary trunk. The pulmonary trunk divides into a right and left pulmonary artery, each of which carries blood to one lung (pulmonary circuit).

OBJ: Beginning with the right atrium, describe blood flow through the normal heart and lungs to the systemic circulation.

18. The primary neurotransmitters of the sympathetic division of the autonomic nervous system

are a. b. c. d.

. dopamine and acetylcholine muscarine and norepinephrine acetylcholine and epinephrine norepinephrine and epinephrine

ANS: D

When sympathetic nerves are stimulated, the neurotransmitters norepinephrine and epinephrine are released.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

19. Complete occlusion of the

coronary artery, also referred to as the widow maker, usually

results in sudden death. a. right b. left main c. circumflex d. left anterior descending ANS: B

Complete occlusion of the left main coronary artery, also referred to as the widow maker, usually results in sudden death.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

20. Stimulation of beta2 receptor sites results in a. increased heart rate b. peripheral vasoconstriction c. constriction of renal blood vessels d. dilation of bronchial smooth muscle ANS: D

.

Beta2 receptor sites are found in the arterioles of the heart, lungs, and skeletal muscle.

Stimulation results in dilation. Stimulation of beta2 receptor sites in the smooth muscle of the bronchi results in dilation.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

21. Chronotropy refers to an effect on . a. heart rate b. force of contraction c. bronchial smooth muscle d. speed of conduction through the atrioventricular node ANS: A

Chrono refers to rate. Chronotropic effect refers to a change in heart rate. Positive chronotropic effect refers to an increase in heart rate. Negative chronotropic effect refers to a decrease in heart rate.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

22. The left main coronary artery divides into the branches. a. marginal and circumflex b. marginal and anterior descending c. anterior and posterior descending d. anterior interventricular artery descending and circumflex ANS: D

The left main coronary artery supplies oxygenated blood to its two primary branches: the left anterior descending (LAD) (also called the anterior interventricular) artery and the circumflex artery (CX).

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

23. The primary neurotransmitter of the parasympathetic division of the autonomic nervous

system is . a. dopamine b. muscarine c. acetylcholine d. norepinephrine ANS: C

Acetylcholine (Ach) is a chemical messenger (neurotransmitter) released when parasympathetic nerves are stimulated. Ach binds to parasympathetic receptors.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

24. The artery supplies the right atrium and ventricle with blood. a. right coronary b. left main coronary c. left circumflex d. left anterior descending

ANS: A

The right coronary artery supplies the right atrium and ventricle with blood.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

25. The tricuspid valve is . a. a semilunar valve b. located between the left ventricle and aorta c. located between the right atrium and right ventricle d. located between the right ventricle and pulmonary artery ANS: C

The tricuspid valve is located between the right atrium and right ventricle.

OBJ: Identify and describe the location of the atrioventricular (AV) and semilunar (SL) valves.

26. When the left ventricle contracts, freshly oxygenated blood flows through the

valve

into the . a. aortic; aorta b. mitral; right atrium c. tricuspid; right ventricle d. pulmonic; pulmonary arteries ANS: A

When the ventricles contract, the semilunar valves open, allowing blood to flow out of the ventricles. When the right ventricle contracts, blood that is low in oxygen flows through the pulmonic valve into the right and left pulmonary arteries. When the left ventricle contracts, freshly oxygenated blood flows through the aortic valve into the aorta and out to the body.

OBJ: Identify and describe the location of the atrioventricular (AV) and semilunar (SL) valves.

27. Thin strands of fibrous connective tissue extend from the atrioventricular (AV) valves to the

papillary muscles and prevent the AV valves from bulging back into the atria during ventricular systole. These strands are called . a. cardiac cilia b. Purkinje fibers c. papillary muscles d. chordae tendineae ANS: D

Chordae tendineae are thin strands of connective tissue. On one end, they are attached to the underside of the AV valves. On the other end, they are attached to small mounds of myocardium called papillary muscles. Papillary muscles project inward from the lower portion of the ventricular walls. When the ventricles contract and relax, so do the papillary muscles. The papillary muscles adjust their tension on the chordae tendineae, preventing them from bulging too far into the atria. Cardiac cilia are not present. Purkinje fibers are related to the electrical system of the heart and not fibrous connective tissue.

OBJ: Identify and describe the location of the atrioventricular (AV) and semilunar (SL) valves.

COMPLETION

is the period during which a heart chamber is contracting and blood is being

1.

ejected.

ANS: Systole OBJ: Identify and discuss each phase of the cardiac cycle.

2. The thick, muscular middle layer of the heart wall that contains the atrial and ventricular

muscle fibers necessary for contraction is the

.

ANS: myocardium OBJ: Identify the three cardiac muscle layers.

3. The

chambers receive blood from the vena cava and coronary sinus.

ANS: right atrium OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

4. The inferior outer surface of the heart is also called the

surface.

ANS: diaphragmatic OBJ: Describe the location of the heart.

5. The

are the heart chambers that pump blood.

ANS: ventricles OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

6.

is the period of relaxation during which a heart chamber is filling.

ANS: Diastole OBJ: Identify and discuss each phase of the cardiac cycle.

TRUE/FALSE 1. Stimulation of beta-adrenergic receptor sites will result in peripheral vasoconstriction.

ANS: F

Beta receptor sites are divided into beta1 and beta2. Beta1 receptors are found in the heart and kidneys. Stimulation of beta1 receptor sites in the heart results in increased heart rate, contractility, and ultimately irritability of cardiac cells. Stimulation of beta1 receptor sites in the kidneys results in the release of renin into the blood. Renin promotes the production of angiotensin, a powerful vasoconstrictor. Beta2 receptor sites are found in the arterioles of the heart, lungs, and skeletal muscle. Stimulation results in dilation. Stimulation of beta2 receptor sites in the smooth muscle of the bronchi results in dilation.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

2. Blood pressure is the result of cardiac output and peripheral vascular resistance.

ANS: T

Blood pressure is equal to cardiac output multiplied by peripheral vascular resistance. Blood pressure is the force exerted by the circulating blood volume on the walls of the arteries.

Peripheral vascular resistance is the resistance to the flow of blood determined by blood vessel diameter and the tone of the vascular musculature.

OBJ: Identify and explain the components of blood pressure and cardiac output.

MATCHING Match each item to the correct description below. a. Acute coronary syndromes b. Chronotropic c. Tamponade d. Chemoreceptors e. Mediastinum f. Myocardial ischemia g. Venous return h. Baroreceptors i. Calcium 1. Sensors in the internal carotid arteries and aortic arch that detect changes in the concentration 2.

3.

4.

5.

6.

7.

8.

9.

of hydrogen ions (pH), oxygen, and carbon dioxide in the blood Space between the lungs that contains the heart, great vessels, trachea, and esophagus, among other structures Specialized nerve tissue located in the internal carotid arteries and the aortic arch that detect changes in blood pressure Electrolyte very important in cardiac muscle contraction.

Amount of blood flowing into the right atrium each minute from the systemic circulation Term used to refer to distinct conditions caused by a similar sequence of pathologic events—a temporary or permanent blockage of a coronary artery Typically results when the heart’s demand for oxygen exceeds its supply from the coronary circulation A negative effect refers to a decrease in heart rate.

A buildup of excess blood or fluid in the pericardial space can cause cardiac .

1. ANS: D

2.

3.

4.

5.

6.

7.

8.

9.

ANS: E ANS: H ANS: I ANS: G ANS: A ANS: F ANS: B ANS: C

SHORT ANSWER 1. List two factors that may affect the heart’s efficiency as a pump.

ANS:

Abnormalities of cardiac muscle, the valves, or the conduction system.

OBJ: Identify and explain the components of blood pressure and cardiac output.

2. Name the valve that separates the right ventricle from the right atrium.

ANS:

Tricuspid valve.

OBJ: Name and identify the location of the atrioventricular (AV) and semilunar (SL) valves.

3. Define systole.

ANS:

Contraction or the ejection of blood from a chamber of the heart.

OBJ: Identify and discuss each phase of the cardiac cycle.

4. What is meant by the term ejection fraction?

ANS:

Ejection fraction is the percentage of blood pumped out of a heart chamber with each contraction. Each ventricle holds about 150 mL when it is full; they normally eject only about half this volume (70 to 80 mL) with each contraction.

OBJ: Identify and explain the components of blood pressure and cardiac output.

5. Explain the Frank-Starling law of the heart.

ANS:

According to the Frank-Starling law of the heart, to a point, the greater the volume of blood in the heart during diastole, the more forceful the cardiac contraction, and the more blood the ventricle will pump (stroke volume). This is important so that the heart can adjust its pumping capacity in response to changes in venous return, such as during exercise. If, however, the ventricle is stretched beyond its physiologic limit, cardiac output may fall because of volume overload and overstretching of the muscle fibers.

OBJ: Identify and explain the components of blood pressure and cardiac output.

6. A patient has a heart rate of 80 beats/min. His stroke volume is 70 mL/beat. Is his cardiac

output normal, decreased, or increased?

ANS:

Output is normal.

Stroke volume = 70 mL/beat Heart rate = 80 beats/minute SV HR = CO 70 mL/beat 80 beats/min = 5600 mL/min = 5.6 L/min Cardiac output = normal (normal is between 4 and 8 L/min) OBJ: Identify and explain the components of blood pressure and cardiac output.

7. Briefly describe parasympathetic innervation of the heart.

ANS:

Parasympathetic (inhibitory) nerve fibers supply the sinoatrial node, atrial muscle, and the atrioventricular junction of the heart by the vagus nerves.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

8. The right atrium receives blood low in oxygen from three vessels. Name them.

ANS:

Superior vena cava, inferior vena cava, and coronary sinus.

OBJ: Beginning with the right atrium, describe blood flow through the normal heart and lungs to the systemic circulation.

9. List three types of sympathetic (adrenergic) receptor sites.

ANS:

There are five main types of sympathetic (adrenergic) receptors: alpha1, alpha2, beta1, beta2, and dopamine (or dopaminergic).

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

10. What factors affect afterload?

ANS:

Afterload is the pressure or resistance against which the ventricles must pump to eject blood.

Afterload is influenced by the following: arterial blood pressure, the ability of the arteries to become stretched (arterial distensibility), and arterial resistance.

OBJ: Identify and explain the components of blood pressure and cardiac output.

11. Define atrial kick.

ANS:

At the end of ventricular diastole, both atria simultaneously contract to eject 10% to 30% more blood into the ventricles.

OBJ: Explain atrial kick.

12. What effects can be expected from sympathetic stimulation of the heart?

ANS:

Sympathetic stimulation of the heart results in increased heart rate, force of contraction, conduction velocity, blood pressure, and cardiac output.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

13. Describe the function of the right atrium of the heart.

ANS:

The right atrium receives deoxygenated blood from the superior vena cava (which carries blood from the head and upper extremities), the inferior vena cava (which carries blood from the lower body), and the coronary sinus (which receives blood from the intracardiac circulation). Blood passes through the tricuspid valve to the right ventricle.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

14. List six of the signs and symptoms of decreased cardiac output.

ANS:

Acute changes in blood pressure; acute changes in mental status; cold, clammy skin; color changes in the skin and mucous membranes; crackles (rales); dyspnea; dysrhythmias; fatigue; orthopnea; restlessness.

OBJ: Identify and explain the components of blood pressure and cardiac output.

15. What effects can be expected from parasympathetic stimulation of the heart?

ANS:

Parasympathetic stimulation has the following actions: it slows the rate of discharge of the SA node, slows conduction through the AV node, decreases the strength of atrial contraction, and can cause a small decrease in the force of ventricular contraction.

OBJ: Compare and contrast the effects of sympathetic and parasympathetic stimulation of the heart.

16. What factors affect stroke volume?

ANS:

Stroke volume is determined by the degree of ventricular filling when the heart is relaxed (preload), the pressure against which the ventricle must pump (afterload), and the myocardium’s contractile state (contracting or relaxing).

OBJ: Identify and explain the components of blood pressure and cardiac output.

17. Your patient is a 62-year-old woman complaining of a “racing heart.” Your examination of the

patient reveals a pulse rate of 192 beats/min. Briefly explain why recognition of a rapid heart rate is important when providing patient care.

ANS:

Increases in heart rate shorten all phases of the cardiac cycle. The most important is that the time the heart spends relaxing is less. If the length of time for ventricular relaxation is shortened, there is less time for them to fill adequately with blood. If the ventricles do not have time to fill, the following occur: the amount of blood sent to the coronary arteries is reduced, the amount of blood pumped out of the ventricles will decrease (cardiac output), and signs of myocardial ischemia may be seen.

OBJ: Identify and explain the components of blood pressure and cardiac output.

18. Name the two main branches of the left coronary artery.

ANS:

The left main coronary artery supplies oxygenated blood to its two primary branches: the left anterior descending (LAD; also called the anterior interventricular) artery and the circumflex artery (CX).

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

ECGs Made Easy 6th Edition Barbara Test Bank

Chapter 02: Basic Electrophysiology Aehlert: ECGs Made Easy, 6th Edition MULTIPLE CHOICE 1. In most patients, the sinoatrial (SA) and atrioventricular (AV) nodes are supplied by the a. b. c. d.

coronary artery. right left main circumflex left anterior descending

ANS: A

The SA node receives its blood supply from the SA node artery that runs lengthwise through the center of the node. The SA node artery originates from the right coronary artery in about 60% of people. The AV node is supplied by the right coronary artery in 85% to 90% of the population. In the remainder, the circumflex artery provides the blood supply.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.

2. The intrinsic rate of the atrioventricular (AV) bundle is a. 20 to 40 b. 40 to 60 c. 60 to 80 d. 80 to 100

beats/min.

ANS: B

The AV bundle has pacemaker cells capable of firing at a rate of 40 to 60 beats/min.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.

3. How do you determine whether the atrial rhythm on an ECG tracing is regular or irregular? a. Compare QT intervals. b. Compare PR intervals. c. Compare R to R intervals. d. Compare P to P intervals.

ANS: D

To evaluate the regularity of the atrial rhythm on a rhythm strip, the interval between two consecutive P waves is measured. The distance between succeeding P-P intervals is measured and compared. If the atrial rhythm is regular, the P-P intervals will measure the same.

OBJ: Describe a systematic approach to the analysis and interpretation of cardiac dysrhythmias.

4.

is the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse without being stimulated from another source, such as a nerve. a. Excitability b. Conductivity c. Automaticity

ECGs Made Easy 6th Edition Barbara Test Bank d. Contractility ANS: C

The ability of cardiac pacemaker cells to create an electrical impulse without being stimulated from another source is called automaticity. Excitability is the heart muscles’ ability to respond to impulse or stimulus. Conductivity is the ability of the cardiac cells to receive and transmit an electrical impulse. Contractility is the contraction of the heart muscle which produces the heartbeat.

OBJ: Describe the primary characteristics of cardiac cells.

5. In the heart’s conduction system, the

receive(s) an electrical impulse from the bundle of His and relay(s) it to the Purkinje fibers in the ventricular myocardium. a. atrioventricular (AV) node b. atria c. sinoatrial (SA) node d. right and left bundle branches ANS: D

The right and left bundle branches divide into smaller and smaller branches and then into a special network of fibers called the Purkinje fibers. These fibers spread from the interventricular septum into the papillary muscles. They continue downward to the apex of the heart, composing an elaborate web that penetrates about one third of the way into the ventricular muscle mass. The fibers then become continuous with the muscle cells of the right and left ventricles.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventicular bundle and purkinje fibers.

6. In the heart’s conduction system, the

receive(s) an electrical impulse from the right and left bundle branches and relay(s) it to the ventricular myocardium. a. AV node b. SA node c. Purkinje fibers d. atrial pacemaker cells ANS: C

The right bundle branch innervates the right ventricle. The left bundle branch spreads the electrical impulse to the interventricular septum and left ventricle.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.

7. What does the QRS complex represent? a. Atrial depolarization b. Ventricular contraction c. Ventricular repolarization d. Ventricular depolarization ANS: D

ECGs Made Easy 6th Edition Barbara Test Bank When the ventricles are stimulated, a QRS complex is recorded on the ECG. Thus, the QRS complex represents ventricular depolarization. Atrial depolarization is initiated by the SA node on the wall of the right atrium, which is symbolized by the P wave that shows on the EKG. Ventricular contraction happens when the cardiac muscles contract within the ventricles, although this contraction is represented by the QRS on the EKG, the most specific answer related to electricity in the heart (and not heart muscle) is ventricular depolarization.

Ventricle repolarization represents the relaxation and journey back to isoelectric baseline, which can include ST segment and T wave.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

8. The normal pacemaker of the heart is the

node, which is found in the

atrium, and

has an intrinsic firing rate of beats/min. sinoatrial; left; 40 to 60 sinoatrial; right; 60 to 100 atrioventricular; left; 20 to 40 atrioventricular; right; 100 to 180

a. b. c. d.

ANS: B

The sinoatrial (SA) node is normally the primary pacemaker of the heart because it has the fastest firing rate of all of the heart’s normal pacemaker sites (60 to 100 beats/min). The SA node is located in the upper posterior part of the right atrium where the superior vena cava and the right atrium meet.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventicular bundle and purkinje fibers.

9. On an ECG, what is the first negative deflection seen after the P wave? a. Q wave b. R wave c. S wave d. T wave ANS: A

A QRS complex normally follows each P wave. The QRS complex begins as a downward deflection—the Q wave. A Q wave is always a negative waveform.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

10. Lead II records the difference in electrical potential between the a. left; left b. left; right c. right; left d. right; right ANS: B

leg and

arm.

ECGs Made Easy 6th Edition Barbara Test Bank Lead II records the difference in electrical potential between the left leg and right arm electrodes. The positive electrode is placed on the left leg and the negative electrode is placed on the right arm. Lead II views the inferior surface of the left ventricle.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

11. Leads II, III, and aVF view the a. anterior b. inferior c. septal d. lateral

surface of the left ventricle.

ANS: B

Leads II, III, and aVF view the inferior surface of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

12. The period during the cardiac cycle when cells cannot respond to a stimulus, no matter how

strong, is called the depolarized supranormal relative refractory absolute refractory

period.

a. b. c. d.

ANS: D

During the absolute refractory period, the cell will not respond to further stimulation. This means that the myocardial working cells cannot contract and the cells of the electrical U San N T impulse—no matter how strong the stimulus. conduction system cannot conduct electrical As a result, tetanic (sustained) contractions cannot be provoked in cardiac muscle. On the ECG, the absolute refractory period corresponds with the onset of the QRS complex to the peak of the T wave. Depolarized is the electrical activity coming back to a baseline level, to the isoelectric line. Supranormal is the electrical potential of the cell. Relative refractory is when the cell requires a stronger than normal stimulus to produce a contraction.

OBJ: Define the absolute, effective, relative refractory, and supranormal periods and their location in the cardiac cycle.

13. Leads I, aVL, V5, and V6 view the a. anterior b. septal c. inferior d. lateral

surface of the left ventricle.

ANS: D

Leads I, aVL, V5, and V6 view the lateral surface of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

14. The absolute refractory period begins with the onset of the a. P wave; with the end of the QRS complex b. QRS complex; at approximately the apex of the T wave

and terminates

.

ECGs Made Easy 6th Edition Barbara Test Bank c. QRS complex; with the end of the T wave d. P wave; with the beginning of the QRS complex ANS: B

On the ECG, the absolute refractory period corresponds with the onset of the QRS complex to the peak of the T wave.

OBJ: Define the absolute, effective, relative refractory, and supranormal periods and their location in the cardiac cycle.

15. The QT interval is measured from the beginning of the a. QRS complex to the end of the T wave b. P wave to the end of the QRS complex c. QRS complex to the beginning of the T wave d. P wave to the beginning of the QRS complex

.

ANS: A

The QT interval is measured from the beginning of the QRS complex to the end of the T wave. In the absence of a Q wave, the QT interval is measured from the beginning of the R wave to the end of the T wave. The term QT interval is used regardless of whether the QRS complex begins with a Q or R wave.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

16. In an adult, the normal duration of the QRS complex is a. 0.12 to 0.20 second b. 0.10 second or less c. 0.04 to 0.14 second d. 0.20 second or less

.

ANS: B

The normal duration of the QRS complex is 0.10 second or less.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

17. The intrinsic rate of the Purkinje fibers is a. 20 to 40 b. 40 to 60 c. 60 to 100 d. 100 to 180

beats/min.

ANS: A

The Purkinje fibers have pacemaker cells capable of firing at a rate of 20 to 40 beats/min.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.

18. The intrinsic rate of the SA node is a. 40 to 60

beats/min.

ECGs Made Easy 6th Edition Barbara Test Bank b. 60 to 100 c. 100 to 180 d. 200 to 260 ANS: B

The intrinsic rate of the SA node is 60 to 100 beats/min.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.

19. On the ECG, the T wave represents a. atrial contraction b. atrial repolarization c. ventricular contraction d. ventricular repolarization

.

ANS: D

Ventricular repolarization is represented on the ECG by the T wave.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

20. On the ECG, the time necessary for the spread of an electrical impulse through the AV node,

bundle of His, right and left bundle branches, and the Purkinje fibers is reflected by the TP segment PR segment QT interval QRS duration

.

a. b. c. d.

ANS: B

The PR segment is the horizontal line between the end of the P wave and the beginning of the QRS complex. It is part of the PR interval and represents activation of the AV node, the bundle of His, the bundle branches, and the Purkinje fibers.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

21. The portion of the ECG tracing between the QRS complex and the T wave is called the a. PR segment b. ST segment c. TP segment d. QT interval

.

ANS: B

The portion of the ECG tracing between the QRS complex and the T wave is the ST segment.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

22. Which of the following is the first positive deflection seen on the ECG after the P wave?

ECGs Made Easy 6th Edition Barbara Test Bank a. b. c. d.

Q wave R wave S wave T wave

ANS: B

If the QRS complex consists entirely of a positive waveform, it is called an R wave. If the complex consists entirely of a negative waveform, it is called a QS wave.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

23.

cells are working cells of the heart that contain contractile filaments and form the muscular layer of the atrial walls and the thicker muscular layer of the ventricular walls. a. Pacemaker b. Myocardial c. Specialized d. Electrical ANS: B

Myocardial cells (working or mechanical cells) contain contractile filaments. When these cells are electrically stimulated, the contractile filaments slide together, and the myocardial cell contracts.

OBJ: Describe the two basic types of cardiac cells in the heart, where they are found, and their function.

24. When the cardiac muscle cell is stimulated the cell is said to a. polarize b. recover c. depolarize d. repolarize

.

ANS: C

The movement of charged particles across a cell membrane causing the inside of the cell to become positive is called depolarization. Depolarization must take place before the heart can mechanically contract and pump blood.

OBJ: Define the terms membrane potential, threshold potential, action potential, polarization, depolarization, and repolarization.

25. On the ECG, the P wave represents atrial a. b. c. d.

and the QRS complex represents ventricular

. depolarization; depolarization repolarization; repolarization repolarization; depolarization depolarization; repolarization

ANS: A

On the ECG, the P wave represents atrial depolarization and the QRS complex represents ventricular depolarization.

ECGs Made Easy 6th Edition Barbara Test Bank

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

26.

is a term used to describe the period of recovery that cells need after being discharged before they are able to respond to a stimulus. a. Irritability b. Conductivity c. Polarization d. Refractoriness ANS: D

Refractoriness is a term used to describe the period of recovery that cells need after being discharged before they are able to respond to a stimulus. In the heart, the refractory period is longer than the contraction itself.

OBJ: Define the absolute, effective, relative refractory, and supranormal periods and their location in the cardiac cycle.

27. Tall, peaked T waves observed on the ECG are most commonly seen in patients with a. hypokalemia b. hyperkalemia c. hyponatremia d. hypernatremia

.

ANS: B

Tall, pointed (peaked) T wavN es aR re cI omm GonBly.sCeenMin hyperkalemia.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

28. Which part of the conduction system receives an impulse from the bundle of His and relays it

to the Purkinje fibers? a. SA node b. AV node c. Right and left atria d. Right and left bundle branches ANS: D

The right and left bundle branches receive an impulse from the bundle of His and relay it to the Purkinje fibers. The conduction system begins with the SA node, travels to the AV node, bundle of His, bundle branches then Purkinje fibers.

OBJ: Describe the normal sequence of electrical conduction through the heart.

29. Which of the following correctly reflects examples of ectopic (latent) pacemakers? a. The SA node and AV junction b. The AV junction and ventricles c. The SA node and right bundle branch d. The AV junction and left bundle branch

ECGs Made Easy 6th Edition Barbara Test Bank

ANS: B

Ectopic pacemakers have to do with the section of electricity between the atria and ventricles, which is between the AV junction and ventricles. The SA node and AV junction are both within the atria. The SA node and right bundle branch is too large of a section, but also too specific when talking about just right bundle branch, it would need to be both right and left.

AV junction and left bundle branch is too large and the ectopic pacemaker does not extend down to the left bundle branch.

OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.

30. The PR interval is considered prolonged if it is more than a. 0.06 b. 0.12 c. 0.18 d. 0.20

seconds in duration.

ANS: D

A PR interval is considered short if it is less than 0.12 second and long if it is more than 0.20 second.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

COMPLETION 1.

is the ability of cardiac cells to spontaneously initiate an electrical impulse without being stimulated from another source.

ANS: Automaticity OBJ: Describe the primary characteristics of cardiac cells.

2. An ECG lead that has a positive and negative electrode is called a(n)

lead.

ANS: bipolar OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

3. The appearance of coved (“frowny face”) ST-segment elevation is called a(n)

.

ANS: acute injury pattern OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, and infarction.

4. A line between waveforms is called a(n)

.

ECGs Made Easy 6th Edition Barbara Test Bank ANS: segment OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

5. The cells of the heart that contain contractile filaments are called

cells.

ANS: myocardial OBJ: Describe the two basic types of cardiac cells in the heart, where they are found, and their function.

6. Name the first positive deflection seen after the P wave on the ECG. ANS: R wave OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

TRUE/FALSE 1. A conduction problem above the level of the bundle branches will largely affect the P wave

and PR interval.

ANS: T OBJ: Define and describe the sigUnifiS cancNe ofTeach ofOthe following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

2. The period of time during the cardiac cycle when cells cannot respond to a stimulus, no matter

how strong, is the relative refractory period.

ANS: F

During the absolute refractory period, the cell will not respond to further stimulation. This means that the myocardial working cells cannot contract and the cells of the electrical conduction system cannot conduct an electrical impulse, no matter how strong the stimulus.

OBJ: Define the absolute, effective, relative refractory, and supranormal periods and their location in the cardiac cycle.

3. Depolarization is the same as contraction.

ANS: F

Depolarization is not the same as contraction. Depolarization (an electrical event) is expected to result in contraction (a mechanical event). It is possible to see organized electrical activity on the cardiac monitor, yet evaluation of the patient reveals no palpable pulse. This clinical situation is called pulseless electrical activity (PEA).

OBJ: Define the terms membrane potential, threshold potential, action potential, polarization,

ECGs Made Easy 6th Edition Barbara Test Bank depolarization, and repolarization.

4. In most ECG leads, a normal Q wave is less than 0.04 second in duration and less than one

third the amplitude of the R wave in that lead.

ANS: T

With the exception of leads III and aVR, a normal Q wave in the limb leads is less than 0.04 second (one small box) in duration and less than one third the height of the R wave in that lead. An abnormal (pathologic) Q wave is more than 0.04 second in duration or more than one third the height of the following R wave in that lead. Myocardial infarction is one possible cause of abnormal Q waves.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

5. The point where the QRS complex and the ST segment meet is called the ST junction or

J-point.

ANS: T

There are different points within the EKG that have specific identifying parts. The J-point is located where the QRS and ST segment meet.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

6. If the wave of depolarization(electrical impulse moves toward the positive electrode, the

waveform recorded on ECG graph paper will be upright (positive deflection).

ANS: T OBJ: Define the terms membrane potential, threshold potential, action potential, polarization, depolarization, and repolarization.

7. In the limb leads, the ST segment is normally isoelectric, or less than 1 mm above or below

the isoelectric line.

ANS: T

The normal ST segment begins at the isoelectric line, extends from the end of the S wave, and curves gradually upward to the beginning of the T wave. In the limb leads, the normal ST segment is isoelectric (flat) but may normally be slightly elevated or depressed (usually by less than 1 mm).

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

MATCHING Match each item to the correct description below. a. Ventricular

ECGs Made Easy 6th Edition Barbara Test Bank b. Atrial c. Repolarization d. Augmented e. Reciprocal changes f. Indicative changes g. Reentry h. Ectopic i. Positive j. Amplitude k. Voltmeter l. Supranormal m. Electrolyte 1. ECG changes observed in leads opposite the affected area of the heart; also called mirror

image changes 2. The QRS complex represents depolarization.

3. Each electrode placed in a “V” position is a(n) electrode.

4. Element or compound that breaks into charged particles (ions) when melted or dissolved in 5.

6.

7.

8.

9.

10.

11.

12.

13.

water or another solvent An ECG machine is a sophisticated .

ECG changes observed in leads that look directly at the affected area of the heart The T wave represents ventricular .

The a in aVR, aVL, and aVF Impulse(s) originating from a source other than the SA node The spread of an impulse through tissue already stimulated by that same impulse Height (voltage) of a waveform on the ECG U S N T O The P wave represents _ depolarization.

During this period, a weaker than normal stimulus can cause depolarization of cardiac cells.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

ANS: E ANS: A ANS: I ANS: M ANS: K ANS: F ANS: C ANS: D ANS: H ANS: G ANS: J ANS: B ANS: L

SHORT ANSWER 1. On the ECG, what do the ST segment and T wave represent?

ANS:

ECGs Made Easy 6th Edition Barbara Test Bank On the ECG, the ST segment represents early ventricular repolarization and the T wave presents ventricular repolarization.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

2. Complete the following chart:

Lead

Positive Electrode

Negative Electrode

Heart Surface Viewed

Positive Electrode Lead I Left arm Lead II Left leg Lead III Left leg

Negative Electrode Right arm Right arm Left arm

Heart Surface Viewed Lateral Inferior Inferior

Lead I Lead II Lead III ANS:

Lead

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

3. Complete the following chart: heart surface Lead Positive

Electrode

Viewed

aVR aVL aVF ANS:

Lead aVR aVL aVF

Positive Electrode Right arm Left arm Left leg

Heart Surface Viewed None Lateral Inferior

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

ESSAY 1. Explain the significance of Einthoven’s triangle.

ANS:

ECGs Made Easy 6th Edition Barbara Test Bank Einthoven’s triangle is a means of illustrating that the two arms and the left leg form the apices of a triangle surrounding the heart. The two apices at the upper part of the triangle represent the points at which the two arms connect electrically with the fluids around the heart. The lower apex is the point at which the left leg connects with the fluids.

OBJ: N/A 2. Generally speaking, what is the normal duration of a QT interval?

ANS:

The duration of the QT interval varies according to age, gender, and particularly heart rate. If the QT interval is less than half the RR interval, it is probably normal.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: P wave, QRS complex, T wave, U wave, PR segment, TP segment, ST segment, PR interval, QRS duration, and QT interval.

3. List four major electrolytes that influence cardiac function.

ANS:

Sodium, potassium, calcium, and chloride.

OBJ: N/A 4. Is depolarization the same as contraction? Explain your answer.

ANS:

Depolarization is not the same U as cS ontN ractiT on..DC epOoM larization (an electrical event) is expected to result in contraction (a mechanical event). It is possible to see organized electrical activity on the cardiac monitor, yet evaluation of the patient reveals no palpable pulse. This clinical situation is called pulseless electrical activity (PEA).

OBJ: Define the terms membrane potential, threshold potential, action potential, polarization, depolarization, and repolarization.

5. List three causes of artifact on an ECG tracing.

ANS:

Artifacts may be due to loose electrodes, broken wires or ECG cables, muscle tremor, patient movement, external chest compressions, or 60-cycle interference.

OBJ: Define the term artifact and explain methods that can be used to minimize its occurrence.

6. List the ECG leads that view the heart in the horizontal plane, allowing a view of the front and

left sides of the heart.

ANS:

Six chest (precordial or V) leads view the heart in the horizontal plane, allowing a view of the front and left sides of the heart. Precordial leads are identified as V1, V2, V3, V4, V5, and V6.

OBJ: Differentiate between the frontal plane and the horizontal plane leads.

Chapter 03: Sinus Mechanisms Aehlert: ECGs Made Easy, 6th Edition

MULTIPLE CHOICE 1. In sinus arrhythmia, a gradual increasing of the heart rate is usually associated with a. expiration b. inspiration c. excessive caffeine intake d. early signs of heart failure

.

ANS: B

Sinus arrhythmia that is associated with the phases of breathing and changes in intrathoracic pressure is called respiratory sinus arrhythmia. The rhythm is irregular; the heart rate increases gradually during inspiration (R-R intervals shorten) and decreases with expiration (R-R intervals lengthen).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrhythmia.

2. The rate of sinus tachycardia is a. slower than 60 b. 40 to 80 c. 60 to 100 d. faster than 100

beats/min.

ANS: D

The rate of sinus tachycardia is between 101 and 180 beats/min.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

3. An ECG rhythm strip shows a ventricular rate of 46 bpm, a regular rhythm, a PR interval of

0.14 seconds, a QRS duration of 0.06 seconds, and one upright P wave before each QRS. This rhythm is . a. sinus rhythm b. sinus bradycardia c. sinus arrest d. sinoatrial block ANS: B

The rhythm described fits the ECG criteria for a sinus bradycardia.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

4.

An ECG rhythm strip shows a ventricular rate of 128 bpm, a regular rhythm, a PR interval of 0.16 seconds, a QRS duration of 0.08 seconds, and one upright P wave before each QRS. This rhythm is sinus . a. arrhythmia b. bradycardia

c. rhythm d. tachycardia ANS: D

The rhythm described fits the ECG criteria for a sinus tachycardia.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

5. Which of the following are possible causes of sinus tachycardia? a. Hypothermia, hypovolemia b. Hypoxia, calcium channel blocker overdose c. Fever, pain, anxiety d. Vomiting, vagal maneuvers ANS: C

Causes of sinus tachycardia include: acute myocardial infarction; caffeine-containing beverages; dehydration, hypovolemia; drugs such as cocaine, amphetamines, ecstasy, cannabis; exercise; fear and anxiety; fever; heart failure; hyperthyroidism; hypoxia; infection; medications such as epinephrine, atropine, and dopamine; nicotine; pain; pulmonary embolism; shock; sympathetic stimulation.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

6. Which of the following are possible causes of sinus bradycardia? a. Elevated temperature, pain b. Increased intracranial pressure, beta-blocker overdose c. Hypoxia, fright, caffeine-containing beverages d. Hypovolemia, administration of sympathomimetics ANS: B

Causes of sinus bradycardia include: disease of the SA node; hyperkalemia; hypokalemia; hypothermia; hypothyroidism; hypoxia; increased intracranial pressure; inferior myocardial infarction (MI); medications such as calcium channel blockers, digitalis, beta-blockers, amiodarone, and sotalol; obstructive sleep apnea; post heart transplant; posterior MI; and vagal stimulation.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

7. The rate of a sinus rhythm is a. slower than 60 b. 60 to 100 c. 80 to 120 d. faster than 100

beats/min.

ANS: B

The rate of a sinus rhythm is between 60 and 100 beats/min.

OBJ: Describe the ECG characteristics of a sinus rhythm.

8. Which of the following may cause a sinus bradycardia? a. Stress or anxiety b. Increased sympathetic tone c. Fever d. Hypothermia ANS: D

Causes of sinus bradycardia include: disease of the SA node; hyperkalemia; hypokalemia; hypothermia; hypothyroidism; hypoxia; increased intracranial pressure; inferior myocardial infarction (MI); medications such as calcium channel blockers, digitalis, beta-blockers, amiodarone, and sotalol; obstructive sleep apnea; post heart transplant; posterior MI; and vagal stimulation.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

9. Which of the following correctly reflects the ECG criteria for a sinus rhythm? a. More P waves than QRS complexes b. P waves that look alike and upright in lead II, one before each QRS complex c. Irregular atrial and ventricular rhythm d. PR interval exceeding 0.20 seconds ANS: B

Characteristics of sinus rhythm: Rhythm R-R and P-P intervals are regular Rate 60 to 100 beats/min P waves Positive (upright) in lead II; one precedes each QRS complex; P waves look alike PR interval 0.12 to 0.20 seconds and constant from beat to beat QRS duration 0.11 seconds or less unless abnormally conducted OBJ: Describe the ECG characteristics of a sinus rhythm.

10. Management of a patient with a sinus tachycardia might include a. identification and treatment of the underlying cause b. administration of atropine c. use of a pacemaker d. vagal maneuvers, such as carotid sinus pressure

.

ANS: A

Treatment for sinus tachycardia is directed at correcting the underlying cause (i.e., fluid replacement, relief of pain, removal of offending medications or substances, reducing fever or anxiety). Sinus tachycardia in a patient experiencing an acute myocardial infarction (MI) may be treated with medications to slow the heart rate and decrease myocardial oxygen demand (e.g., beta-blockers), provided there are no signs of heart failure or other contraindications.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

11. The rate of a sinus bradycardia is a. slower than 60

beats/min.

b. 60 to 100 c. 80 to 120 d. faster than 100 ANS: B

If the SA node fires at a rate that is slower than normal for the patient’s age, the rhythm is called sinus bradycardia. The rhythm starts in the SA node and then travels the normal conduction pathway, resulting in atrial and ventricular depolarization. In adults and adolescents, a sinus bradycardia has a heart rate of less than 60 beats/min. The term severe sinus bradycardia is sometimes used to describe a sinus bradycardia with a rate of less than 40 beats/min.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

SHORT ANSWER 1. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 70 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

2. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia at 48 beats/min with ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

3. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 65 beats/min with ST-segment depression OBJ: Describe the ECG characteristics of a sinus rhythm.

4. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 98 beats/min with ST-segment elevation OBJ: Describe the ECG characteristics of a sinus rhythm.

5. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at a rate of 36 to 71 beats/min with an episode of SA block OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinoatrial block.

6. Identify the following rhythm:

ANS:

Sinus rhythm at 71 beats/min with a wide QRS, ST-segment depression OBJ: Describe the ECG characteristics of a sinus rhythm.

7. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at a rate of 24 to 81 beats/min with an episode of sinus arrest OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrest.

8. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 140 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

9. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 65 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

10. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 167 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

11. Identify the following rhythm (lead II):

ANS:

Sinus rhythm with a wide QRS at 100 beats/min; ST-segment depression, inverted T waves OBJ: Describe the ECG characteristics of a sinus rhythm.

12. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 111 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

13. Identify the following rhythm (lead II):

ANS:

Sinus rhythm (borderline sinus bradycardia) at 60 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

14. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia at 58 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

15. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 85 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

16. Identify the following rhythm (lead II):

ANS:

Sinus arrhythmia at 52 to 94 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrhythmia.

17. Identify the following rhythm (lead I):

ANS:

Sinus tachycardia at 150 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

18. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia at 40 beats/min; ST-segment depression, inverted T waves OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

19. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 95 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

20. Identify the following rhythm (lead II):

ANS:

Sinus arrhythmia at 71 to 100 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrhythmia.

21. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 71 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

22. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia at 44 beats/min, ST-segment depression. Note the upright U waves following each T wave.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

23. Identify the following rhythm:

ANS:

Sinus rhythm at 75 beats/min, ST-segment depression OBJ: Describe the ECG characteristics of a sinus rhythm.

24. Identify the following rhythm (lead II):

ANS:

Sinus rhythm with a wide QRS at 83 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

25. Identify the following rhythm (lead II):

ANS:

Sinus arrhythmia at 64 to 94 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrhythmia.

26. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 94 beats/min with a wide (and notched) QRS, ST-segment depression OBJ: Describe the ECG characteristics of a sinus rhythm.

27. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 0 to 75 beats/min with an episode of sinus arrest; tall T waves OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrest.

28. List three significant signs and/or symptoms that, if observed with a sinus bradycardia, would

require management of this dysrhythmia.

ANS:

Clinical signs and symptoms of hemodynamic compromise can include: acute changes in mental status; chest pain or discomfort; cold, clammy skin; fall in urine output; heart failure; low blood pressure; pulmonary congestion; shock; and shortness of breath.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

29. Complete the following ECG criteria for a sinus rhythm:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

P-P interval regular, R-R interval regular.

60 to 100 beats/min.

Positive (upright) in lead II, one precedes each QRS complex, P waves look alike.

0.12 to 0.20 seconds and constant from beat to beat.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics of a sinus rhythm.

30. Complete the following ECG criteria for a sinus bradycardia:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

P-P interval regular, R-R interval regular.

Less than 60 beats/min.

Positive (upright) in lead II, one precedes each QRS complex, P waves look alike.

0.12 to 0.20 seconds and constant from beat to beat.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

31. Complete the following ECG criteria for a sinus tachycardia:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

PR interval QRS duration

P-P interval regular, R-R interval regular.

101 to 180 beats/min.

Positive (upright) in lead II, one precedes each QRS complex, P waves look alike; at very fast rates, it may be hard to tell the difference between a P wave from a T wave.

0.12 to 0.20 seconds (may shorten with faster rates) and constant from beat to beat.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

32. Complete the following ECG criteria for a sinoatrial (SA) block:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm

Rate P waves PR interval QRS duration

Irregular because of the pause caused by the SA block; the pause is the same as (or an exact multiple of) the distance between two other P-P intervals.

Usually normal, but varies because of the pause.

Positive (upright) in lead II, P waves look alike; when present, one precedes each QRS complex.

0.12 to 0.20 seconds and constant from beat to beat.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinoatrial block.

33. Complete the following ECG criteria for a sinus arrest:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm

Rate P waves PR interval QRS duration

Irregular—the pause is of undetermined length (more than one PQRST complex is missing) and is not the same distance as other P-P intervals.

Usually normal, but varies because of the pause.

Positive (upright) in lead II, P waves look alike; when present, one precedes each QRS complex.

0.12 to 0.20 seconds and constant from beat to beat.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrest.

34. Complete the following ECG criteria for a sinus arrhythmia:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm

Rate P waves PR interval QRS duration

Irregular, phasic with breathing; heart rate increases gradually during inspiration (R-R intervals shorten) and decreases with expiration (R-R intervals lengthen).

Usually 60-100 beats/min, but may be slower or faster.

Positive (upright) in lead II, one precedes each QRS complex, P waves look alike.

0.12 to 0.20 seconds and constant from beat to beat.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus arrhythmia.

Chapter 04: Atrial Rhythms Aehlert: ECGs Made Easy, 6th Edition TRUE/FALSE 1. Individuals with preexcitation syndrome are predisposed to tachydysrhythmias.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia (AVRT).

2. In atrial fibrillation, the AV node attempts to protect the ventricles from the hundreds of

impulses bombarding it per minute by blocking many of the impulses generated by the irritable sites in the atria.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

3. Upon conversion of atrial fibrillation to sinus rhythm, the patient should be observed for signs

of a possible stroke.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

4. The presence of an accessory pathway should be considered in atrial fibrillation with a

ventricular rate faster than 180 beats/min.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia (AVRT).

5. Most patients with type I atrial flutter develop atrial fibrillation.

ANS: F

Patients with type II atrial flutter, which is also called atypical or very rapid atrial flutter, often develop atrial fibrillation. The precise mechanism of type II atrial flutter has not been defined. In type II atrial flutter, the atrial rate ranges from 350 to 450 beats/min.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

6. In atrial fibrillation, fibrillatory waves are referred to as f waves.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

7. Delivery of an electrical current timed for delivery during the QRS complex is called

defibrillation.

ANS: F

Synchronized cardioversion is the delivery of a shock to the heart by means of a defibrillator to terminate a rapid dysrhythmia. A synchronized shock means that the shock is timed to avoid the relative refractory period of the cardiac cycle. On the ECG, this period occurs during the peak of the T wave to approximately the end of the T wave. Defibrillation is the delivery of an electrical current across the heart muscle over a very brief period to terminate an abnormal heart rhythm. Defibrillation is also called unsynchronized countershock or asynchronous countershock, because the delivery of current has no relationship to the cardiac cycle.

OBJ: Discuss the indications and procedure for synchronized cardioversion.

8. Multifocal atrial tachycardia is another name for atrial fibrillation.

ANS: F

When a wandering atrial pacemaker rhythm is associated with a ventricular rate of more than 100 beats/min, the dysrhythmia is called multifocal atrial tachycardia (MAT) or chaotic atrial tachycardia.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for multifocal atrial tachycardia (MAT).

9. A macroreentrant circuit is one that involves a small area of heart tissue, usually a few

centimeters or less.

ANS: F

Macroreentry circuits and microreentry circuits are two main types of reentry circuits. If the reentry circuit involves conduction through a large area of the heart, such as the entire right or left atrium, it is called a macroreentry circuit. A reentry circuit involving conduction within a small area is called a microreentry circuit.

OBJ: Explain the concepts of altered automaticity, triggered activity, and reentry.

10. The ventricular rhythm in atrial fibrillation is usually “irregularly irregular.”

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

MULTIPLE CHOICE 1. What is meant by the term controlled atrial fibrillation? a. The overall ventricular rate is less than 100 beats/min. b. The atrial rate is less than 100 beats/min. c. The overall ventricular rate is greater than 100 beats/min. d. The atrial rate is greater than 100 beats/min.

ANS: A

Atrial flutter or atrial fibrillation that has a ventricular rate of less than 100 beats/min is described as controlled. A controlled ventricular rate may be the result of a healthy atrioventricular (AV) node protecting the ventricles from very fast atrial impulses or medications used to control (block) conduction through the AV node, decreasing the number of impulses reaching the ventricles.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

2. Which of the following correctly describes multifocal atrial tachycardia? a. Atrial rhythm is regular. b. Ventricular rhythm is irregular. c. Atrial and ventricular rhythms are regular. d. Atrial and ventricular rhythms are irregular.

ANS: D

Characteristics of multifocal atrial tachycardia: Rhythm Usually irregular as the pacemaker site shifts from the SA node to ectopic atrial locations or AV junction Rate Faster than 100 beats/min P waves Size, shape, and direction may change from beat to beat; it may be upright, inverted, biphasic, rounded, flat, pointed, notched, or buried in the QRS complex PR interval Varies as the pacemaker site shifts from the SA node to ectopic atrial locations or AV junction QRS duration 0.11 seconds or less unless abnormally conducted OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for multifocal atrial tachycardia (MAT).

3. The most common type of supraventricular tachycardia (SVT) is a. atrial tachycardia b. atrial flutter c. AV reentrant tachycardia (AVRT) d. AV nodal reentrant tachycardia (AVNRT)

.

ANS: D

AVNRT is the most common type of SVT. It is caused by reentry in the area of the AV node.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular nodal reentrant tachycardia (AVNRT).

4. Atrial fibrillation is characterized by . a. one P wave before each QRS and a regular ventricular rate of 60 to 100 beats/min b. an erratic, wavy baseline and irregular ventricular rhythm c. “saw-tooth”– or “picket-fence”–shaped waveforms preceding each QRS d. P waves occurring before, during, or after the QRS complex; when seen, they are

inverted ANS: B

Characteristics of atrial fibrillation:

Rhythm Rate P waves PR interval QRS duration

Ventricular rhythm usually irregularly irregular Atrial rate usually 400 to 600 beats/min; ventricular rate variable No identifiable P waves, fibrillatory waves present; erratic, wavy baseline Not measurable 0.11 seconds or less unless abnormally conducted

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

5. How are frequent PACs usually managed? a. Defibrillation b. Synchronized cardioversion c. Correcting the underlying cause d. Administration of medications such as atropine or epinephrine ANS: C

PACs usually do not require treatment if they are infrequent. The patient may complain of a “skipped beat” or occasional “palpitations” if PACs are frequent or may be unaware of their occurrence. In susceptible individuals, frequent PACs may induce episodes of atrial fibrillation or paroxysmal supraventricular tachycardia (PSVT). Frequent PACs are treated by correcting the underlying cause (e.g., correcting electrolyte imbalances, reducing stress, reducing or eliminating stimulants, treating heart failure). If the patient is symptomatic, frequent PACs may be treated with beta-blockers, such as atenolol or metoprolol.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

6. A wandering atrial pacemaker rhythm with a ventricular rate of 60 to 100/min may also be

referred to as . atrial flutter atrial fibrillation multifocal atrial tachycardia multiformed atrial rhythm

a. b. c. d.

ANS: D

Multiformed atrial rhythm is an updated term for the rhythm formerly known as wandering atrial pacemaker. When a wandering atrial pacemaker rhythm is associated with a ventricular rate of more than 100 beats/min, the dysrhythmia is called multifocal atrial tachycardia (MAT) or chaotic atrial tachycardia.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for wandering atrial pacemaker (multiformed atrial rhythm).

7. Identify the following rhythm (lead II).

a. Atrial fibrillation

b. Sinus arrhythmia c. Multifocal atrial tachycardia d. Sinus tachycardia with premature atrial complexes (PACs) ANS: D

The rhythm shown is a sinus tachycardia with premature atrial complexes (PACs).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

8. P waves in this rhythm strip

a. b. c. d.

.

are upright before every QRS complex are inverted before every QRS complex vary in size and shape are not identifiable

ANS: D

P waves are not identifiable in the rhythm strip provided.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

9. Identify the following rhythm (lead II).

a. b. c. d.

Sinus arrhythmia Atrial tachycardia Multifocal atrial tachycardia with a PAC Sinus rhythm with a PAC, a run of PSVT, back to a sinus rhythm

ANS: D

The rhythm strip shows a sinus rhythm with a PAC, a run of PSVT, and then a change in the rhythm back to a sinus rhythm.

OBJ: Explain the terms paroxysmal atrial tachycardia (PAT) and paroxysmal supraventricular tachycardia (PSVT).

10. P waves in this rhythm strip

.

a. are upright before every QRS complex

b. are inverted before every QRS complex c. vary in size and shape d. are not identifiable ANS: C

This rhythm strip shows multifocal atrial tachycardia in which the P waves vary in size and shape.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for multifocal atrial tachycardia (MAT).

11. Identify the following rhythm (lead II).

a. b. c. d.

Sinus arrhythmia Sinus tachycardia Sinus rhythm with a PAC Sinus tachycardia with a PAC

ANS: C

This rhythm strip shows a sinus tachycardia with a premature atrial complex.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

12. Identify the following rhythm (lead II).

a. b. c. d.

Atrial flutter Atrial fibrillation Wolff-Parkinson-White syndrome AV nodal reentrant tachycardia (AVNRT)

ANS: A

This rhythm strip shows atrial flutter.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

13. P waves in this rhythm strip

a. occur regularly

.

b. are not identifiable; fibrillatory waves are present c. are upright before every QRS complex d. are not identifiable; flutter waves are present ANS: D

This rhythm strip shows atrial flutter. P waves are not identifiable; flutter waves are present.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

14. To determine whether the ventricular rhythm on an ECG tracing is regular or irregular,

compare a. PR b. R to R c. TP d. P to P

intervals.

ANS: B

To evaluate the rhythmicity of the ventricular rhythm on a rhythm strip, the interval between two consecutive R waves is measured. The distance between succeeding R-R intervals is measured and compared. If the ventricular rhythm is regular, the R-R intervals will measure the same.

OBJ: Identify how heart rates, durations, and amplitudes may be determined from electrocardiographic recordings.

15. A 77-year-old woman is complaining of a sudden onset of palpitations. The cardiac monitor

reveals atrial fibrillation with a ventricular response of 144 to 210 beats/min while the patient is at rest. In this situation, the ventricular rate associated with this rhythm is considered to be . a. controlled b. uncontrolled ANS: B

Atrial flutter or atrial fibrillation that has a ventricular rate of less than 100 beats/min is described as controlled. A controlled ventricular rate may be the result of a healthy AV node protecting the ventricles from very fast atrial impulses or medications used to control (block) conduction through the AV node, decreasing the number of impulses reaching the ventricles.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

COMPLETION 1. Delivery of an electrical current timed for delivery during the QRS complex is called

.

ANS: synchronized cardioversion OBJ: Discuss the indications and procedure for synchronized cardioversion.

2. Sometimes, when a premature atrial complex (PAC) occurs very prematurely and close to the

T wave of the preceding beat, only a P wave may be seen with no QRS after it (appearing as a pause). This type of PAC is termed a PAC. ANS:

nonconducted blocked OBJ: Describe the electrocardiogram (ECG) characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

3. PACs associated with a wide QRS complex are called

PACs, indicating that

conduction through the ventricles is abnormal.

ANS: aberrantly conducted OBJ: Describe the electrocardiogram (ECG) characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

4. An accessory pathway that has one end attached to normal conductive tissue is called a(n)

.

ANS: bypass tract OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia (AVRT).

SHORT ANSWER 1. Complete the following ECG criteria for atrial tachycardia:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

PR interval QRS duration

Regular.

100 to 250 beats/min.

One P wave precedes each QRS complex in lead II; P waves differ in shape from sinus P waves; an isoelectric baseline is usually present between P waves; if the atrial rhythm originates in the low portion of the atrium, P waves will be negative in lead II. With rapid rates, it is difficult to distinguish P waves from T waves.

May be shorter or longer than normal.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial tachycardia (AT).

2. Complete the following ECG criteria for AV nodal reentrant tachycardia (AVNRT):

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

PR interval QRS duration

Ventricular rhythm is usually very regular.

150 to 250 beats/min (usually 180 to 200 beats/min in adults).

P waves are often hidden in the QRS complex. If the ventricles are stimulated first and then the atria, a negative (inverted) P wave will appear after the QRS in leads II, III, and aVF. When the atria are depolarized after the ventricles, the P wave typically distorts the end of the QRS complex.

P waves are not seen before the QRS complex, therefore the PR interval is not measurable.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular nodal reentrant tachycardia (AVNRT).

3. Complete the following ECG criteria for Wolff-Parkinson-White (WPW)

syndrome: Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

Regular, unless associated with atrial fibrillation.

Usually 60 to 100 beats/min, if the underlying rhythm is sinus in origin.

Normal and positive in lead II unless WPW is associated with atrial fibrillation.

If P waves are observed, less than 0.12 seconds.

Usually greater than 0.12 seconds; slurred upstroke of the QRS complex (delta wave) possibly seen in one or more leads.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia (AVRT).

4. Complete the following ECG criteria for atrial flutter:

Rhythm Rate P waves PR interval

QRS duration ANS:

Rhythm Rate

P waves PR interval QRS duration

Atrial regular, ventricular regular or irregular depending on AV conduction or blockade.

Atrial rate 250 to 450 beats/min, typically 300 beats/min; ventricular rate variable, determined by AV blockade; the ventricular rate will usually not exceed 180 beats/min because of the intrinsic conduction rate of the AV junction.

No identifiable P waves; saw-toothed “flutter” waves are present.

Not measurable.

0.11 seconds or less, but may be widened if flutter waves are buried in the QRS complex or if abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

5. Complete the following ECG criteria for atrial fibrillation:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

Ventricular rhythm usually irregularly irregular.

Atrial rate usually 400 to 600 beats/min; ventricular rate variable.

No identifiable P waves, fibrillatory waves present; erratic, wavy baseline.

Not measurable.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

6. Identify the following rhythm (lead II):

ANS:

Sinus rhythm with a nonconducted (blocked) PAC OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

7. Identify the following rhythm (lead II):

ANS:

Multifocal atrial tachycardia (MAT) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for multifocal atrial tachycardia (MAT).

8. Identify the following rhythm (lead II):

ANS:

Atrial tachycardia OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial tachycardia (AT).

9. Identify the following rhythm (lead II):

ANS:

Atrial fibrillation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

10. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 78 beats/min with a PAC, ST segment elevation (PAC is the third complex from left)

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

11. Identify the following rhythm (lead II):

ANS:

Atrial tachycardia at 170 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial tachycardia (AT).

12. Identify the following rhythm (lead II):

ANS:

Uncontrolled atrial fibrillation at 115 to 224 beats/min, ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

13. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 93 beats/min with a PAC OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

14. Identify the following rhythm (lead II):

ANS:

Atrial fibrillation at 54 to 115 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

15. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 117 beats/min with two PACs (beats 8 and 10 from the left are PACs) and a wide QRS, ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

16. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 60 with two nonconducted (blocked) PACs, ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

17. Identify the following rhythm (lead II):

ANS:

Atrial fibrillation at 68 to 115 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

18. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 83 beats/min with frequent PACs (atrial bigeminy), ST segment depression, inverted T waves (beats 3, 5, 7, and 9 are PACs) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

19. Identify the following rhythm (lead II):

ANS:

Underlying rhythm is sinus, but pacemaker site varies; ventricular rate approximately 70 beats/min; patient with known WPW. Note delta waves.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia (AVRT).

20. Identify the following rhythm (lead MCL1):

ANS:

Atrial fibrillation at 79 to 164 beats/min (lead MCL1) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

21. Identify the following rhythm (lead III):

ANS:

Atrial flutter at 85 beats/min (lead III)

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

22. Identify the following rhythm:

ANS:

Atrial flutter at 64 to 83 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

23. Identify the following rhythm (lead II):

ANS:

AVNRT at 186 beats/min with ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular nodal reentrant tachycardia (AVNRT).

24. Identify the following rhythm:

ANS:

Atrial flutter at 75 to 107 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

25. Identify the following rhythm (lead II):

ANS:

AVNRT at 188 beats/min with ST segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular nodal reentrant tachycardia (AVNRT).

26. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 79 beats/min with PACs OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

27. Identify the following rhythm (lead II):

ANS:

Controlled atrial fibrillation at 29 beats/min; this patient was diagnosed with digitalis toxicity OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

28. Identify the following rhythm (lead II):

ANS:

Atrial flutter with a ventricular response of 68 to 150 beats/min

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

29. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 111 beats/min with a nonconducted PAC OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes (PACs).

30. Identify the following rhythm:

ANS:

Controlled atrial fibrillation at 55 to 94 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

31. Identify the following rhythm:

ANS:

Atrial flutter at 88 beats/min with ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

Chapter 05: Junctional Rhythms Aehlert: ECGs Made Easy, 6th Edition TRUE/FALSE 1. The AV junction consists of the AV node and the nonbranching portion of the bundle of His. ANS: T OBJ: Describe the location, function, and (where appropriate), the intrinsic rate of the following structures: sinoatrial (SA) node, atrioventricular (AV) bundle, and Purkinje fibers.

2. An escape rhythm is initiated by a lower pacemaker site when the sinoatrial (SA) node slows

or fails to initiate an impulse.

ANS: T OBJ: Describe the location, function, and (where appropriate) the intrinsic rate of the following structures: sinoatrial (SA) node, atrioventricular (AV) bundle, and Purkinje fibers.

3. Adenosine is the drug of choice when treating a symptomatic patient with a junctional rhythm

at a rate of 40 beats/min.

ANS: F

Atropine (not adenosine) is the drug of choice when treating a symptomatic patient with a junctional rhythm at a rate of 40 beats/min.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

4. The pacemaker cells in the AV junction are located near the nonbranching portion of the

bundle of His. ANS: T OBJ: Describe the location, function, and (where appropriate) the intrinsic rate of the following structures: sinoatrial (SA) node, atrioventricular (AV) bundle, and Purkinje fibers.

MULTIPLE CHOICE 1. A beat originating from the AV junction that appears later than the next expected sinus beat is

called a . junctional escape beat period of SA block premature junctional complex (PJC) premature atrial complex (PAC)

a. b. c. d.

ANS: A

Junctional complexes may come early (before the next expected sinus beat) or late (after the next expected sinus beat). If the complex is early, it is called a premature junctional complex.

If the complex is late, it is called a junctional escape beat. To determine whether a complex is early or late, you need to see at least two sinus beats in a row to establish the regularity of the underlying rhythm.

OBJ: Explain the difference between premature junctional complexes and junctional escape beats.

2. Which of the following medications increases heart rate by accelerating the SA node

discharge rate and blocking the vagus nerve?

Digitalis Atropine Amiodarone Beta-blocker

a. b. c. d.

ANS: B

Atropine is a vagolytic drug that is used to increase the heart rate. Vago refers to the vagus nerves (right and left), which are the main nerves of the parasympathetic division of the autonomic nervous system. Lytic refers to “lyse,” which means “to interfere with.” Atropine works by blocking acetylcholine at the endings of the vagus nerves. The vagus nerves innervate the heart at the SA and AV nodes. Thus, atropine is most effective for narrow-QRS bradycardia. By blocking the effects of acetylcholine, atropine allows more activity from the sympathetic division of the autonomic nervous system. As a result, the rate at which the SA node can fire is increased. Areas of the heart that are not innervated or that are minimally innervated by the vagus nerves (e.g., the ventricles) will not respond to atropine. Thus, atropine is usually ineffective for the treatment of wide-QRS bradycardia. Atropine also increases the rate at which an impulse is conducted through the AV node. It has little or no effect on the force of contraction.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

3. In a junctional rhythm viewed in lead II, where is the location of the P wave on the ECG if

atrial and ventricular depolarization occur simultaneously? a. Before the QRS complex b. During the QRS complex c. After the QRS complex ANS: B

If the atria and ventricles depolarize at the same time, a P wave will not be visible because it will be hidden in the QRS complex.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

4. Common causes of junctional dysrhythmias may include acute coronary syndromes and a. b. c. d.

. hyperthyroidism hypovolemia digitalis toxicity hypoxia

ANS: C

Toxicity or excess of digitalis is a common cause of junctional dysrhythmias.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

5. Identify the following rhythm (lead II).

a. b. c. d.

Accelerated junctional rhythm Sinus rhythm Junctional rhythm Sinus arrhythmia

ANS: A

The rhythm strip shows an accelerated junctional rhythm.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

6. Identify the following rhythm (lead II).

a. b. c. d.

Sinus arrhythmia Sinus rhythm with junctional escape beats Sinus tachycardia with premature atrial complexes Sinus tachycardia with premature junctional complexes

ANS: D

The rhythm strip shows a sinus tachycardia with premature junctional complexes.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature junctional complexes (PJCs).

7. Identify the following rhythm (lead II).

a. b. c. d.

Junctional tachycardia Sinus rhythm with PACs Sinus rhythm with PJCs Accelerated junctional rhythm

ANS: D

The rhythm strip shows an accelerated junctional rhythm.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency

care for an accelerated junctional rhythm.

8. A junctional escape rhythm occurs because of . a. severe chronic obstructive pulmonary disease b. multiple irritable sites firing within the AV junction c. slowing of the rate of the heart's primary pacemaker d. intrathoracic pressure changes associated with the normal respiratory cycle ANS: C

The atrioventricular (AV) junction may assume responsibility for pacing the heart if (1) the sinoatrial (SA) node fails to discharge (such as sinus arrest), (2) an impulse from the SA node is generated but blocked as it exits the SA node (such as SA block), (3) the rate of discharge of the SA node is slower than that of the AV junction (such as a sinus bradycardia or the slower phase of a sinus arrhythmia), and (4) an impulse from the SA node is generated and is conducted through the atria, but is not conducted to the ventricles (such as an AV block).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

9. In a junctional rhythm viewed in lead II, where is the location of the P wave on the ECG if

atrial depolarization precedes ventricular depolarization? a. Before the QRS complex b. During the QRS complex c. After the QRS complex ANS: A

If the AV junction paces the heart and the atria depolarize before the ventricles, an inverted P wave will be seen before the QRS complex and the PR interval will usually measure 0.12 seconds or less. The PR interval is shorter than usual because an impulse that begins in the AV junction does not have to travel as far to stimulate the ventricles.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

10. The usual rate of nonparoxysmal junctional tachycardia is a. 50 to 80 b. 80 to 120 c. 101 to 140 d. 150 to 300

beats/min.

ANS: C

Nonparoxysmal (i.e., gradual onset) junctional tachycardia usually starts as an accelerated junctional rhythm, but the heart rate gradually increases to more than 100 beats/min. The usual ventricular rate for nonparoxysmal junctional tachycardia is 101 to 140 beats/min.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for junctional tachycardia.

11. The atrioventricular (AV) junction consists of the . a. SA and AV nodes b. AV node and the Purkinje fibers c. AV node and nonbranching portion of the bundle of His

d. AV node, bundle of His, and the right and left bundle branches ANS: C

The AV node and the nonbranching portion of the bundle of His are called the AV junction.

The bundle of His has pacemaker cells that are capable of discharging at a rhythmic rate of 40 to 60 beats/min.

OBJ: Describe the location, function, and (where appropriate) the intrinsic rate of the following structures: sinoatrial (SA) node, atrioventricular (AV) bundle, and Purkinje fibers.

12. If seen, the P wave of a rhythm originating in the AV junction will appear a. upright b. inverted c. tall and peaked d. wide and notched

in lead II.

ANS: B

If the AV junction paces the heart, the electrical impulse must travel in a backward (retrograde) direction to activate the atria. If a P wave is seen, it will be inverted in leads II, III, and aVF because the impulse is traveling away from the positive electrode.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

13. Depending on the severity of the patient’s signs and symptoms, management of slow rhythms

originating from the AV junction may require intervention including defibrillation intravenous atropine synchronized cardioversion vagal maneuvers or adenosine, or both

.

a. b. c. d.

ANS: B

Atropine, administered intravenously, is the drug of choice for symptomatic bradycardia.

Defibrillation, synchronized cardioversion, vagal maneuvers, and adenosine are not indicated in the treatment of slow cardiac rhythms.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

COMPLETION 1. A(n)

pause often follows a PJC and represents the delay during which the SA node resets its rhythm for the next beat.

ANS: noncompensatory OBJ: Explain the difference between a compensatory and noncompensatory pause.

2. If the AV junction paces the heart, the electrical impulse must travel in a backward direction to

activate the atria. This is called ANS: retrograde

conduction.

OBJ: Explain the difference between premature junctional complexes and junctional escape beats.

3. A beat originating from the AV junction that appears later than the next expected sinus beat is

called a(n)

.

ANS: junctional escape beat OBJ: Explain the difference between premature junctional complexes and junctional escape beats.

SHORT ANSWER 1. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 136 beats/min with frequent PJCs (the PJCs are beats 2, 5, 8, and 11 from the left) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature junctional complexes (PJCs).

2. Identify the following rhythm (lead II):

ANS:

Accelerated junctional rhythm at 75 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

3. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 75 beats/min

OBJ: Describe the ECG characteristics of a sinus rhythm.

4. Identify the following rhythm (lead II):

ANS:

Sinus rhythm changing to an accelerated junction rhythm at 79 beats/min back to a sinus rhythm OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

5. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 94 beats/min with a PAC (second beat from left) and a junctional escape beat (third beat from left) OBJ: Describe the ECG characteristics and possible causes for junctional escape beats.

6. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 115 beats/min with a PJC (beat 5 is the PJC) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature junctional complexes (PJCs).

7. Identify the following rhythm (lead II):

ANS:

Junctional escape rhythm at 52 beats/min with elevated T waves

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

8. Identify the following rhythm (lead II):

ANS:

Junctional rhythm at 45 beats/min; ST segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

9. Identify the following rhythm (lead II):

ANS:

Junctional rhythm at 37 beats/min converting to a sinus rhythm OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

10. Identify the following rhythm (lead II):

ANS:

Accelerated junctional rhythm at 83 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

11. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 125 beats/min changing to a junctional tachycardia at 125 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for junctional tachycardia.

12. Identify the following rhythm:

ANS:

Junctional rhythm at 44 beats/min; ST segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

13. Identify the following rhythm (lead II):

ANS:

Narrow-QRS tachycardia (probably junctional tachycardia) at 138 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for junctional tachycardia.

14. Identify the following rhythm (lead II):

ANS:

Accelerated junctional rhythm at 100 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

15. Identify the following rhythm:

ANS:

Sinus rhythm at 63 beats/min with PJCs (junctional trigeminy) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature junctional complexes (PJCs).

16. Identify the following rhythm:

ANS:

Sinus bradycardia at 33 beats/min to junctional bradycardia at 32 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

17. Identify the following rhythm:

ANS:

Atrial flutter at 58 to 79 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial flutter.

18. Identify the following rhythm:

ANS:

Accelerated junctional rhythm at 75 beats/min; ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

19. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 70 beats/min with a nonconducted PAC (note distortion of the T wave of the beat preceding the pause) and a junctional escape beat OBJ: Describe the ECG characteristics and possible causes for junctional escape beats.

20. Identify the following rhythm (lead II):

ANS:

Junctional bradycardia at 30 beats/min to sinus bradycardia at 56 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

21. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 90 beats/min with a PJC OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature junctional complexes (PJCs).

22. Identify the following rhythm (lead II):

ANS:

Atrial fibrillation at 65 to 103 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

23. Identify the following rhythm (lead II):

ANS:

Accelerated junctional rhythm at 75 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

24. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 107 beats/min with a junctional escape beat (third beat from the left) and a nonconducted PAC (buried in the T wave of the fourth beat from the left) OBJ: Describe the ECG characteristics and possible causes for junctional escape beats.

25. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 64 beats/min with an episode of sinus arrest and a junctional escape beat OBJ: Explain the difference between premature junctional complexes and junctional escape beats.

26. Identify the following rhythm (lead II):

ANS:

Junctional bradycardia with a ventricular response of 19 to 26 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

27. Complete the following ECG criteria for a junctional escape rhythm:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval

QRS duration

Regular.

40 to 60 beats/min.

May occur before, during, or after the QRS; if visible, the P wave is inverted in leads II, III, and aVF. If a P wave occurs before the QRS, the PR interval will usually be 0.12 sec or less; if no P wave occurs before the QRS, there will be no PR interval.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

28. List four reasons why the AV junction may assume responsibility for pacing the heart.

ANS:

The AV junction may assume responsibility for pacing the heart if: (1) the SA node fails to discharge (such as sinus arrest), (2) an impulse from the SA node is generated but blocked as it exits the SA node (such as SA block), (3) the rate of discharge of the SA node is slower than that of the AV junction (such as a sinus bradycardia or the slower phase of a sinus arrhythmia), (4) an impulse from the SA node is generated and is conducted through the atria but is not conducted to the ventricles (such as an AV block).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

29. Complete the following ECG criteria for a junctional tachycardia:

Rhythm Rate

P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval

QRS duration

Regular.

101 to 180 beats/min.

May occur before, during, or after the QRS; if visible, the P wave is inverted in leads II, III, and aVF. If a P wave occurs before the QRS, the PR interval will usually be 0.12 sec or less; if no P wave occurs before the QRS, there will be no PR interval.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for junctional tachycardia.

30. Complete the following ECG criteria for an accelerated junctional rhythm:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval

QRS duration

Regular.

61 to 100 beats/min.

May occur before, during, or after the QRS; if visible, the P wave is inverted in leads II, III, and aVF. If a P wave occurs before the QRS, the PR interval will usually be 0.12 sec or less; if no P wave occurs before the QRS, there will be no PR interval.

0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

31. Indicate the ventricular rates for each of the following junctional dysrhythmias:

A. Junctional bradycardia B. Junctional tachycardia C. Accelerated junctional rhythm D. Junctional rhythm ANS:

A. Slower than 40 beats/min B. 101 to 180 beats/min C. 61 to 100 beats/min D. 40 to 60 beats/min

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm, for an accelerated junctional rhythm, and for initial emergency care for junctional tachycardia.

Chapter 06: Ventricular Rhythms Aehlert: ECGs Made Easy, 6th Edition

TRUE/FALSE 1. The term premature ventricular complex is technically more correct than premature ventricular

contraction.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

2. Transcutaneous pacing is the treatment of choice for pulseless ventricular tachycardia or

ventricular fibrillation.

ANS: F

Cardiopulmonary resuscitation and defibrillation are the treatments of choice for pulseless ventricular tachycardia or ventricular fibrillation.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for ventricular fibrillation.

3. Medications to suppress an idioventricular rhythm should generally be avoided.

ANS: T OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

4. An idioventricular (ventricular escape) rhythm has an intrinsic rate of 40 to 60 beats/min.

ANS: F

An idioventricular rhythm (IVR), which is also called a ventricular escape rhythm, exists when three or more ventricular escape beats occur in a row at a rate of 20 to 40 beats/min (i.e., the intrinsic firing rate of the Purkinje fibers).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

5. Sustained monomorphic VT is often associated with underlying heart disease, particularly

myocardial ischemia, and rarely occurs in patients without underlying structural heart disease.

ANS: T

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT.

MULTIPLE CHOICE 1. Which of the following best describes an idioventricular rhythm? a. Rapid, chaotic rhythm with no pattern or regularity b. Gradual alteration in the amplitude and direction of the QRS; atrial rate

indiscernible; ventricular rate 150 to 250 beats/min c. Essentially regular ventricular rhythm with QRS complexes measuring 0.12

seconds or greater; atrial rate not discernible; ventricular rate 20 to 40 beats/min d. Regular ventricular rhythm with QRS complexes measuring less than 0.10 seconds; P waves may occur before, during, or after the QRS; ventricular rate 40 to 60 beats/min ANS: C

An idioventricular rhythm (IVR), which is also called a ventricular escape rhythm, exists when three or more ventricular escape beats occur in a row at a rate of 20 to 40 beats/min (i.e., the intrinsic firing rate of the Purkinje fibers). The QRS complexes seen in IVR are wide and bizarre because the impulses begin in the ventricles, bypassing the normal conduction pathway. When the ventricular rate slows to a rate of less than 20 beats/min, some practitioners refer to the rhythm as an agonal rhythm or dying heart.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

2. What is meant by the term pulseless electrical activity (PEA)? a. A chaotic rhythm that is likely to degenerate into cardiac arrest b. An organized rhythm on the cardiac monitor (other than VT), although a pulse is

not present c. A slow rhythm with a wide QRS complex d. A flat line on the cardiac monitor ANS: B

If the patient is not breathing and has no pulse despite the appearance of organized electrical activity on the cardiac monitor (other than VT), pulseless electrical activity (PEA) exists.

OBJ: Explain the term pulseless electrical activity.

3. How would you differentiate a junctional escape rhythm at 40 beats/min from a ventricular

escape rhythm at the same rate? a. It is impossible to differentiate a junctional escape rhythm from a ventricular escape rhythm.

b. The junctional escape rhythm will have a narrow QRS complex; the ventricular

escape rhythm will have a wide QRS complex. c. The rate (40 beats/min) would indicate a junctional escape rhythm, not a ventricular escape rhythm. d. The junctional escape rhythm will have a wide QRS complex; the ventricular escape rhythm will have a narrow QRS complex.

ANS: B

Although junctional and ventricular rhythms are ectopic pacemaker sites, their rhythms can generally be differentiated by the width of their QRS complexes. The junctional escape rhythm will have a narrow QRS complex; the ventricular escape rhythm will have a wide QRS complex.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

4. Which of the following best describes an accelerated idioventricular rhythm (AIVR)? a. Rapid, chaotic rhythm with no pattern or regularity b. Gradual alteration in the amplitude and direction of the QRS; atrial rate

indiscernible, ventricular rate 150 to 250 beats/min c. Regular ventricular rhythm with QRS complexes measuring 0.10 seconds or less; P waves may occur before, during or after the QRS; ventricular rate 41 to 60 beats/min d. Essentially regular ventricular rhythm with QRS complexes measuring 0.12 seconds or greater; atrial rate not discernible; ventricular rate 41 to 100 beats/min ANS: D

Characteristics of accelerated idioventricular rhythm: Rhythm Ventricular rhythm is essentially regular.

Rate 41 to 100 (41 to 120 per some cardiologists) beats/min P waves Usually absent or, with retrograde conduction to the atria, may appear after the QRS (usually upright in the ST segment or T wave) PR interval None QRS duration Greater than 0.12 seconds; the T wave frequently in the opposite direction of the QRS complex OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated idioventricular rhythm.

5. The rate of an idioventricular rhythm is a. 20 to 40 b. 41 to 60 c. 61 to 100 d. 101 to 180

beats/min.

ANS: A

The intrinsic rate of an idioventricular rhythm, which is also called a ventricular escape rhythm, is 20 to 40 beats/min (i.e., the intrinsic firing rate of the Purkinje fibers).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

SHORT ANSWER 1. List four reasons why the ventricles may assume responsibility for pacing the heart.

ANS:

The ventricles may assume responsibility for pacing the heart if the sinoatrial (SA) node fails to discharge, an impulse from the SA node is generated but blocked as it exits the SA node, the rate of discharge of the SA node is slower than that of the ventricles, or an irritable site in either ventricle produces an early beat or rapid rhythm.

OBJ: N/A 2. Complete the following ECG criteria for ventricular fibrillation:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

Rapid and chaotic with no pattern or regularity.

Cannot be determined because there are no discernible waves or complexes to measure.

Not discernible.

Not discernible.

Not discernible.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for ventricular fibrillation.

3. Identify the following rhythm (lead II):

ANS:

Monomorphic ventricular tachycardia at 150 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT. 4. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia with a PVC (third complex from the left) and a fusion beat (fourth complex from the left) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

5. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia with multiform PVCs OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

6. Identify the following rhythm (lead II):

ANS:

Idioventricular rhythm (ventricular escape rhythm) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

7. Identify the following rhythm (lead II):

ANS:

Accelerated idioventricular rhythm (AIVR) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated idioventricular rhythm.

8. Complete the following ECG criteria for asystole:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

Ventricular not discernible; atrial may be discernible.

Ventricular not discernible but atrial activity may be observed (i.e., P-wave asystole).

Usually not discernible.

Not measurable.

Absent.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for asystole.

9. Identify the following rhythm (lead II):

ANS:

Monomorphic ventricular tachycardia OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT. 10. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia with an interpolated PVC and ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

11. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia with frequent uniform PVCs OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

12. Identify the following rhythm (lead II):

ANS:

Polymorphic VT

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for PMVT. 13. Complete the following ECG criteria for an accelerated idioventricular rhythm:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

PR interval QRS duration

Ventricular rhythm is essentially regular.

41 to 100 (41 to 120 per some cardiologists) beats/min.

Usually absent or, with retrograde conduction to the atria, may appear after the QRS (usually upright in the ST segment or T wave).

None.

Greater than 0.12 seconds; the T wave is frequently in the opposite direction of the QRS complex.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated idioventricular rhythm.

14. Identify the following rhythm (lead II):

ANS:

Fine ventricular fibrillation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for ventricular fibrillation.

15. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 60 beats/min with an R-on-T interpolated PVC OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

16. Complete the following ECG criteria for polymorphic ventricular tachycardia:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves PR interval QRS duration

Ventricular rhythm may be regular or irregular.

Ventricular rate 150 to 300 beats/min; typically 200 to 250 beats/min.

None.

None.

0.12 seconds or more; there is a gradual alteration in the amplitude and direction of the QRS complexes; a typical cycle consists of 5 to 20 QRS complexes.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for PMVT. 17. Identify the following rhythm (lead II):

ANS:

Sinus rhythm with a run of VT (i.e., nonsustained VT) and one episode of ventricular couplets OBJ: Explain the terms sustained and nonsustained VT, monomorphic VT, and polymorphic VT. 18. List three potential sites of origin of ectopic beats.

ANS:

Atria (PACs); AV junction (PJCs); and ventricles (PVCs) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

19. Identify the following rhythm (lead II):

ANS:

Sinus tachycardia at 102 beats/min with uniform PVCs; ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

20. Identify the following rhythm (lead II):

ANS:

Accelerated idioventricular rhythm (AIVR) at 42 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated idioventricular rhythm.

21. Identify the following rhythm (lead II):

ANS:

Sinus rhythm with two R-on-T PVCs

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

22. List four common causes of premature ventricular complexes.

ANS:

Common causes of PVCs include acid-base imbalance, acute coronary syndromes, cardiomyopathy, digitalis toxicity, electrolyte imbalance (e.g., potassium, magnesium), exercise, heart failure, hypoxia, an increase in catecholamines and sympathetic tone (e.g., emotional stress, anxiety), medications (e.g., sympathomimetic drugs), normal variant, stimulants (e.g., caffeine, tobacco), valvular heart disease, and ventricular aneurysm.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

23. What is the name given to polymorphic VT that occurs in the presence of a long QT interval?

ANS:

Polymorphic VT that occurs in the presence of a long QT interval is called torsades de pointes.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for PMVT. 24. Complete the following ECG criteria for monomorphic ventricular tachycardia:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

PR interval QRS duration

Ventricular rhythm is essentially regular.

101 to 250 (121 to 250 per some cardiologists) beats/min.

Usually not seen; if present, they have no set relationship with the QRS complexes that appear between them at a rate different from that of the VT. None.

0.12 seconds or greater; often difficult to differentiate between the QRS and T wave.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT.

25. Identify the following rhythm (lead II):

ANS:

Polymorphic VT at 250 to 333 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for PMVT. 26. Identify the following rhythm (lead II):

ANS:

Accelerated idioventricular rhythm (AIVR) at 94 beats/min (lead III) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated idioventricular rhythm.

27. Complete the following ECG criteria for an idioventricular rhythm:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

PR interval QRS duration

Ventricular rhythm is essentially regular.

Ventricular rate 20 to 40 beats/min.

Usually absent or, with retrograde conduction to the atria; may appear after the QRS (usually upright in the ST segment or T wave).

None.

0.12 seconds or greater; the T wave is frequently in the opposite direction of the QRS complex.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care

for an idioventricular rhythm.

28. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia at 54 beats/min with ventricular bigeminy; ventricular rate approximately 100 beats/min if PVCs counted in the rate OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

29. Identify the following rhythm (lead II):

ANS:

Coarse ventricular fibrillation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for ventricular fibrillation.

30. Identify the following rhythm (lead II):

ANS:

Idioventricular rhythm at less than 25 beats/min (may also be called an agonal rhythm when ventricular rate is less than 20 beats/min) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

31. Identify the following rhythm (lead II):

ANS:

P-wave asystole OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for asystole.

32. Identify the following rhythm (lead II):

ANS:

Polymorphic VT OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for PMVT. 33. Identify the following rhythm:

ANS:

Sinus rhythm at 94 beats/min with an episode of couplets and a run of VT (i.e., nonsustained VT) OBJ: Explain the terms sustained and nonsustained VT, monomorphic VT, and polymorphic VT. 34. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 94 beats/min OBJ: Describe the ECG characteristics of a sinus rhythm.

35. Identify the following rhythm (lead II):

ANS:

Ventricular fibrillation, shock (defibrillation), idioventricular rhythm at 40 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an idioventricular rhythm.

36. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 62 beats/min with an interpolated PVC; inverted T waves OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

37. Identify the following rhythm (lead II):

ANS:

Narrow-QRS tachycardia (SVT) at 147 beats/min with ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular nodal reentrant tachycardia (AVNRT).

38. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 88 beats/min with a PVC and a run of VT, ST-segment depression, inverted T waves OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

39. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 94 beats/min to monomorphic ventricular tachycardia (VT) at 150 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT. 40. Identify the following rhythm (lead II):

ANS:

Agonal rhythm, asystole OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for asystole.

41. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 83 beats/min with ventricular trigeminy OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

42. Identify the following rhythm (lead II):

ANS:

Atrial fibrillation with a rapid ventricular response of 150 to 250 beats/min and a run of VT. OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT. 43. Identify the following rhythm (lead II):

ANS:

Sinus bradycardia at 30 beats/min with ventricular bigeminy (ventricular rate approximately 60 if PVCs counted), inverted T waves, horizontal ST-segments OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

44. Identify the following rhythm:

ANS:

Sinus rhythm at 86 beats/min with uniform PVCs OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes.

45. Identify the following rhythm:

ANS:

Monomorphic VT at 150 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for monomorphic VT. 46. Identify the following rhythm (lead II):

ANS:

Coarse ventricular fibrillation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for ventricular fibrillation.

47. Identify the following rhythm (lead II):

ANS:

Sinus rhythm at 60 beats/min with a PAC OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes.

48. Identify the following rhythm:

ANS:

Sinus bradycardia at 52 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus bradycardia.

49. Identify the following rhythm (lead II):

ANS:

Accelerated junctional rhythm at 79 beats/min with ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for an accelerated junctional rhythm.

50. Identify the following rhythm (lead II):

ANS:

Sinus beat to junctional escape rhythm at 52 beats/min with inverted T waves OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

Chapter 07: Atrioventricular Blocks Aehlert: ECGs Made Easy, 6th Edition TRUE/FALSE 1. The ventricular rhythm is regular in second-degree AV block type I. ANS: F

With second-degree AV block type I, the ventricular rhythm is irregular. The atrial rate is regular (i.e., Ps plot through on time). Grouped beating may be present.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 2. The QRS complex associated with a third-degree AV block is always wide.

ANS: F

The site of block in a third-degree AV block may be the AV node or, more commonly, the bundle of His or the bundle branches. A secondary pacemaker (either junctional or ventricular) stimulates the ventricles; therefore the QRS may be narrow or wide, depending on the location of the escape pacemaker and the condition of the intraventricular conduction system.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

MULTIPLE CHOICE 1. In 2:1 AV block, the PR interval a. shortens b. lengthens c. is absent d. remains constant

.

ANS: D

Second-degree 2:1 AV block is characterized by P waves that are normal in size and shape, but every other P wave is not followed by a QRS. The atrial rate is twice the ventricular rate. The PR interval for the conducted beats is constant.

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

2. The PR interval of a first-degree AV block . a. is constant and less than 0.12 seconds in duration b. is constant and more than 0.20 seconds in duration c. is generally progressive until a P wave appears without a QRS complex d. gradually decreases in duration until a P wave appears without a QRS complex ANS: B

A first-degree AV block is present when there is a 1:1 relationship between P waves and QRS complexes and the PR interval is prolonged (i.e., more than 0.20 seconds) and constant.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for first-degree AV block.

3. An ECG rhythm strip shows a regular ventricular rhythm at a rate of 30 beats/min, more P

waves than QRS complexes (the P waves occur regularly), a variable PR interval, and a QRS duration of 0.14 seconds. This rhythm is . a. 2:1 AV block b. third-degree AV block c. second-degree AV block type I d. second-degree AV block type II ANS: B

With a third-degree block, the ventricular and atrial rhythms are regular; however, AV dissociation is present. The ventricular rate is determined by the origin of the escape rhythm.

Based on the description provided (i.e., a QRS duration of 0.14 seconds and a ventricular rate of 30 beats/min), the escape pacemaker is probably ventricular in origin. P waves are normal in size and shape, but some P waves are not followed by a QRS complex. There is no true PR interval because the atria and the ventricles beat independently of each other. The QRS may be narrow or wide, depending on the location of the escape pacemaker and the condition of the intraventricular conduction system.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

4. A 2:1 AV block is characterized by intervals. a. irregular P to P b. irregular R to R c. regular P to P intervals and regular R to R d. irregular P to P intervals and regular R to R ANS: C

Second-degree 2:1 AV block is characterized by regular P-P and R-R intervals. P waves are normal in size and shape, but every other P wave is not followed by a QRS. The atrial rate is twice the ventricular rate.

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

5. Second-degree AV block type II is characterized by a. irregular P to P b. irregular R to R c. regular P to P intervals and regular R to R d. irregular P to P intervals and irregular R to R

intervals.

ANS: B

With second-degree AV block type II the ventricular rhythm is irregular. There are more P waves than QRS complexes and the P-P interval is regular. P waves are normal in size and shape, but some P waves are not followed by a QRS complex. The PR interval may be within normal limits or prolonged, but it is constant for the conducted beats; the PR intervals before and after a blocked P wave are constant.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency

management for second-degree AV block type II. 6. Second-degree AV block type I is characterized by a. irregular P to P b. regular R to R c. regular P to P intervals and irregular R to R d. irregular P to P intervals and irregular R to R

intervals.

ANS: C

Second-degree AV block type I is characterized by an irregular ventricular rhythm (i.e., irregular R to R intervals), more P waves than QRS complexes, and P waves that occur regularly (i.e., regular P to P intervals).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 7. In second-degree and third-degree AV blocks, a. P waves occur regularly b. every other P wave is dropped c. P waves are periodically dropped d. there are more QRS complexes than P waves

.

ANS: A

In second-degree and third-degree AV blocks, there are more P waves than QRS complexes and the P waves occur regularly.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

8. In second-degree AV block type I, the PR interval a. shortens b. is absent c. is inconstant d. remains constant

.

ANS: C

In second-degree AV block type I, the PR interval is inconstant and the PR interval after a nonconducted P wave is shorter than the interval preceding the nonconducted beat.

Although progressive lengthening is a phrase that was used for many years to describe the behavior of the PR intervals associated with second-degree AV block type I, use of this terminology is no longer recommended; rather, the term inconstant or generally progressive PR intervals is recommended. Use of the term inconstant or generally progressive PR intervals is important because many type I AV blocks are atypical, missing one or more of the features of the classic Wenckebach phenomenon. For example, the second conducted PR interval after a blocked impulse may fail to show the greatest increase in length; instead, the PR interval may actually shorten and then lengthen in the middle of a grouped beating pattern.

Alternately, the duration of the PR intervals may show no obvious change in the middle or for a few beats just before the end of a group.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I.

9. In 2:1 AV block, . a. the atrial rhythm (P-P interval) is regular b. the ventricular rhythm (R-R interval) is irregular c. the PR interval lengthens until a P wave appears with no QRS complex d. there is no PR interval because the atria and ventricles beat independently of each

other ANS: A

Second-degree 2:1 AV block is characterized by P waves that are normal in size and shape, but every other P wave is not followed by a QRS. The atrial rate is twice the ventricular rate.

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

10. In third-degree AV block, . a. the atrial rhythm (P-P interval) is irregular b. the ventricular rhythm (R-R interval) is irregular c. there is no PR interval because the atria and ventricles beat independently of each

other d. the PR interval after a nonconducted P wave is shorter than the interval preceding the nonconducted beat ANS: C

In third-degree atrioventricular (AV) block, both the atrial and ventricular rhythms are regular, but the atria and ventricles beat independently; therefore the P waves that are present are unrelated to the QRS complexes (i.e., AV dissociation exists).

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

11. Most of the bundle branch tissue is supplied by the a. right b. left

coronary artery.

ANS: B

Most of the bundle branch tissue is supplied by a branch of the left coronary artery.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

COMPLETION 1. A

bundle branch block produces a QS pattern in lead V1.

ANS: left OBJ: Describe the appearance of right and left bundle branch block as seen in lead V1.

2. A

bundle branch block produces a RSR pattern in lead V1.

ANS: right OBJ: Describe the appearance of right and left bundle branch block as seen in lead V1.

SHORT ANSWER 1. Indicate the ECG criteria for the following dysrhythmias:

Third-Degree AV Block

2:1 AV Block

Ventricular Rhythm PR interval QRS width ANS:

Ventricular Rhythm PR interval QRS width

Third-Degree AV Block

2:1 AV Block

Regular None Narrow or wide

Regular Constant Narrow or wide

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

2. Complete the following ECG criteria for 2:1 AV block:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

Ventricular regular; atrial regular (Ps plot through on time).

Atrial rate is twice the ventricular rate.

Normal in size and shape; every other P wave is not followed by a QRS complex (i.e., more Ps than QRSs).

PR interval Constant.

QRS duration May be narrow or wide; complexes are absent after every other P wave.

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

3. Complete the following ECG criteria for third-degree AV block:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm

Ventricular regular; atrial regular (Ps plot through); no relationship between the atrial and ventricular rhythms (i.e., AV dissociation is present).

Rate

The ventricular rate is determined by the origin of the escape rhythm; the atrial rate is greater than (and independent of) the ventricular rate; ventricular rate is determined by the origin of the escape rhythm.

P waves Normal in size and shape; some P waves are not followed by a QRS complex (i.e., more Ps than QRSs).

PR interval None. The atria and the ventricles beat independently of each other; therefore there is no true PR interval.

QRS duration Narrow or wide, depending on the location of the escape pacemaker and the condition of the intraventricular conduction system.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

4. Complete the following ECG criteria for second-degree AV block type II:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate

Ventricular irregular; atrial regular (i.e., Ps plot through on time).

Atrial rate is greater than the ventricular rate; ventricular rate is often slow.

P waves Normal in size and shape; some P waves are not followed by a QRS complex (i.e., more Ps than QRSs).

PR interval Within normal limits or prolonged but constant for the conducted beats; the PR intervals before and after a blocked P wave are constant.

QRS duration Within normal limits if the block occurs above or within the bundle of His; greater than 0.11 seconds if the block occurs below the bundle of His; complexes are periodically absent after P waves.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type II. 5. Complete the following ECG criteria for second-degree AV block type I:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

Ventricular irregular; atrial regular (i.e., Ps plot through on time); grouped beating may be present.

Atrial rate is greater than the ventricular rate.

Normal in size and shape; some P waves are not followed by a

PR interval QRS duration

QRS complex (i.e., more Ps than QRSs).

Inconstant; the PRI after a nonconducted P wave is shorter than the interval preceding the nonconducted beat.

Usually 0.11 seconds or less; complexes periodically dropped.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 6. Complete the following ECG criteria for first-degree AV block:

Rhythm Rate P waves PR interval QRS duration ANS:

Rhythm Rate P waves

Regular.

Usually within normal range, but depends on underlying rhythm.

Normal in size and shape; one positive (upright) P wave before each QRS. PR interval Prolonged (i.e., more than 0.20 seconds) but constant.

QRS duration Usually 0.11 seconds or less unless abnormally conducted.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for first-degree AV block.

7. Identify the following rhythm:

ANS:

Sinus rhythm at 60 beats/min with a first-degree AV block OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for first-degree AV block.

8. Identify the following rhythm:

ANS:

Third-degree AV block with a ventricular escape rhythm OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency

management for third-degree AV block.

9. Identify the following rhythm:

ANS:

Third-degree AV block at 33 beats/min, ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

10. Identify the following rhythm:

ANS:

Second-degree AV block type I at 47 to 88 beats/min, ST-segment elevation; the fourth beat from the left is a fusion beat OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 11. Identify the following rhythm:

ANS:

Second-degree AV block type I at a rate of less than 20 to 94 beats/min (leads II and III) OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 12. Identify the following rhythm:

ANS:

Second-degree AV block type I at 50 to 94 beats/min, ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 13. Identify the following rhythm:

ANS:

2:1 AV block at 40 beats/min, ST-segment depression OBJ: Describe 2:1 AV block and advanced second-degree AV block.

14. Identify the following rhythm:

ANS:

Third-degree AV block at 50 beats/min, ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

15. Identify the following rhythm:

ANS:

2:1 AV block at 30 beats/min OBJ: Describe 2:1 AV block and advanced second-degree AV block.

16. Identify the following rhythm:

ANS:

2:1 AV block at 60 beats/min OBJ: Describe 2:1 AV block and advanced second-degree AV block.

17. Identify the following rhythm:

ANS:

Second-degree AV block type I at 43 to 60 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 18. Identify the following rhythm:

ANS:

Advanced second-degree AV block at 20 to 60 beats/min OBJ: Describe 2:1 AV block and advanced second-degree AV block.

19. Identify the following rhythm:

ANS:

Sinus rhythm with first-degree AV block; ST-segment elevation OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for first-degree AV block.

20. Identify the following rhythm:

ANS:

Third-degree AV block with a junctional escape rhythm OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

21. Identify the following rhythm:

ANS:

Sinus tachycardia with first-degree AV block at 107 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for first-degree AV block.

22. Identify the following rhythm:

ANS:

Third-degree AV block at 38 beats/min with ST-segment depression and inverted T waves OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

23. Identify the following rhythm:

ANS:

2:1 AV block at 36 beats/min OBJ: Describe 2:1 AV block and advanced second-degree AV block.

24. Identify the following rhythm:

ANS:

Sinus tachycardia at 107 beats/min with uniform PVCs OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature ventricular complexes (PVCs).

25. Identify the following rhythm:

ANS:

Sinus rhythm at 68 beats/min with first-degree AV block, ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for first-degree AV block.

26. Identify the following rhythm:

ANS:

Second-degree AV block type I at 38 to 75 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 27. Identify the following rhythm:

ANS:

Advanced second-degree AV block at 48 to 83 beats/min; ST-segment depression OBJ: Describe 2:1 AV block and advanced second-degree AV block.

28. Identify the following rhythm:

ANS:

2:1 AV block at 36 beats/min OBJ: Describe 2:1 AV block and advanced second-degree AV block.

29. Identify the following rhythm:

ANS:

Third-degree AV block at 45 beats/min OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for third-degree AV block.

30. Identify the following rhythm:

ANS:

Second-degree AV block type I at 60 to 98 beats/min; ST-segment depression OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 31. Identify the following rhythm:

ANS:

2:1 AV block at 34 beats/min; ST-segment depression; tall T waves

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

32. Indicate the ECG criteria for the following dysrhythmias.

Second-Degree AV Block Type I

Third-Degree AV Block

Ventricular Rhythm PR Interval QRS Width ANS:

Second-Degree AV Block Type I Ventricular Rhythm PR Interval QRS Width

Third-Degree AV Block

Irregular Inconstant; generally progressive Usually narrow

Regular None Narrow or wide

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management for second-degree AV block type I. 33. Indicate the ECG criteria for the following dysrhythmias.

Second-Degree AV Block Type I

Third-Degree AV Block

Ventricular Rhythm PR Interval QRS Width ANS:

Second-Degree AV Block Type II Ventricular Rhythm PR Interval QRS Width

Irregular Constant Narrow or wide

2:1 AV Block Regular Constant Narrow or wide

OBJ: Describe 2:1 AV block and advanced second-degree AV block.

Chapter 08: Pacemaker Rhythms Aehlert: ECGs Made Easy, 6th Edition MULTIPLE CHOICE 1. In pacing, sensitivity refers to . a. the ability of a pacemaker to recognize and respond to intrinsic electrical activity b. a pacing lead with a single electrical pole at the distal tip of the pacing lead

through which the stimulating pulse is delivered c. the successful conduction of an artificial pacemaker’s impulse through the

myocardium, resulting in depolarization d. the length of time between an atrial sensed or atrial paced event and the delivery

of a ventricular pacing stimulus ANS: A

Sensitivity refers to the extent to which an artificial pacemaker recognizes intrinsic cardiac electrical activity.

OBJ: Discuss the terms triggering, inhibition, pacing, capture, electrical capture, mechanical capture, and sensitivity.

2. The first letter of the pacemaker identification code represents a. the chamber sensed b. the chamber paced c. the mode of response d. programmable functions

.

ANS: B

The first letter of the code identifies the heart chamber (or chambers) paced (stimulated). A pacemaker used to pace only a single chamber is represented by either A (atrial) or V (ventricular). A pacemaker capable of pacing in both chambers is represented by D (dual).

OBJ: N/A 3. Capture is . a. the electrical stimulus delivered by a pacemaker’s pulse generator b. a vertical line on the ECG that indicates the pacemaker has discharged c. the time measured between a sensed cardiac event and the next pacemaker output d. the ability of a pacing stimulus to successfully depolarize the cardiac chamber that

is being paced ANS: D

Capture is the successful conduction of an artificial pacemaker’s impulse through the myocardium, resulting in depolarization.

OBJ: Discuss the terms triggering, inhibition, pacing, capture, electrical capture, mechanical capture, and sensitivity.

4. In pacing, rate modulation refers to . a. the ability of a pacemaker to recognize and respond to intrinsic electrical activity b. the minimum level of electrical current needed to consistently depolarize the

myocardium c. the ability of a pacemaker to increase the pacing rate in response to physical

activity or metabolic demand d. a pacing lead with a single electrical pole at the distal tip of the pacing lead

through which the stimulating pulse is delivered.

ANS: C

Rate modulation refers to a pacemaker’s ability to adapt its rate to meet the body’s needs caused by increased physical activity and then increase or decrease the pacing rate accordingly. A pacemaker’s rate modulation capability may also be referred to as rate responsiveness or rate adaptation.

OBJ: N/A 5. The second letter of the pacemaker identification code represents a. programmable functions b. the chamber sensed c. the mode of response d. the chamber paced

.

ANS: B

The second letter of the pacemaker code identifies the chamber of the heart where patientinitiated (i.e., intrinsic) electrical activity is sensed by the pacemaker.

OBJ: N/A 6. In pacing, threshold refers to . a. the ability of a pacemaker to recognize and respond to intrinsic electrical activity b. the minimum level of electrical current needed to consistently depolarize the

myocardium c. a pacing lead with a single electrical pole at the distal tip of the pacing lead

through which the stimulating pulse is delivered d. the ability of a pacemaker to increase the pacing rate in response to physical

activity or metabolic demand ANS: B

Threshold refers to the minimum level of electrical current needed to consistently depolarize the myocardium.

OBJ: Discuss the terms triggering, inhibition, pacing, capture, electrical capture, mechanical capture, and sensitivity.

COMPLETION 1. A demand pacemaker is also known as a

pacemaker.

ANS: synchronous or noncompetitive OBJ: Explain the differences between single-chamber and dual-chamber pacemakers, and between fixed-rate and demand pacemakers.

2. A(n)

is a vertical line on the ECG that indicates the artificial pacemaker has

discharged.

ANS: pacemaker spike OBJ: N/A SHORT ANSWER 1. Identify the following rhythm:

ANS:

Normal functioning dual-chamber pacemaker at 80 pulses/min OBJ: Describe how to analyze pacemaker function on the ECG. 2. Identify the following rhythm:

ANS:

Ventricular paced rhythm with 100% capture OBJ: Describe how to analyze pacemaker function on the ECG. 3. Identify the following rhythm:

ANS:

Ventricular paced rhythm with pacemaker malfunction—loss of capture OBJ: Describe how to analyze pacemaker function on the ECG. 4. Identify the following rhythm:

ANS:

Ventricular paced rhythm with 100% capture OBJ: Describe how to analyze pacemaker function on the ECG. 5. Explain the benefits of a dual-chamber pacemaker.

ANS:

The dual-chamber pacemaker stimulates the right atrium and right ventricle sequentially (stimulating first the atrium, then the ventricle), mimicking normal cardiac physiology and thus preserving the atrial contribution to ventricular filling (i.e., atrial kick).

OBJ: Explain the differences between single-chamber and dual-chamber pacemakers, and between fixed-rate and demand pacemakers.

6. Describe what is meant by the term overdrive pacing.

ANS:

During overdrive pacing, the pacemaker is set to pace at a rate faster than the rate of the tachycardia. After a few seconds, the pacemaker is stopped to allow the return of the heart’s intrinsic pacemaker.

OBJ: N/A 7. Explain the difference between electrical capture and mechanical capture.

ANS:

During pacing, the cardiac monitor is observed for electrical capture, usually evidenced by a wide QRS and broad T wave. In some patients, electrical capture is less obvious, indicated only as a change in the shape of the QRS. Mechanical capture is evaluated by assessing the patient’s right upper extremity or right femoral pulses.

OBJ: Discuss the terms triggering, inhibition, pacing, capture, electrical capture, mechanical capture, and sensitivity.

8. Your patient has a VVI pacemaker. Briefly explain the meaning of each of these letters.

ANS:

A ventricular demand (VVI) pacemaker is a common type of pacemaker. With this device, the pacemaker electrode is placed in the right ventricle (V); the ventricle is sensed (V) and the pacemaker is inhibited (I) when spontaneous ventricular depolarization occurs within a preset interval. When spontaneous ventricular depolarization does not occur within this preset interval, the pacemaker fires and stimulates ventricular depolarization at a preset rate.

OBJ: Explain the differences between single-chamber and dual-chamber pacemakers, and between

fixed-rate and demand pacemakers.

9. Your patient has a DDD pacemaker. Briefly explain the meaning of each of these letters.

ANS:

A dual-chamber pacemaker can also be called a DDD pacemaker, indicating that both the atrium and ventricle are paced (D), both chambers are sensed (D), and the pacemaker has both a triggered and an inhibited mode of response (D). When spontaneous atrial depolarization does not occur within a preset interval, the atrial pulse generator fires and stimulates atrial depolarization at a preset rate. The pacemaker is programmed to wait, simulating the normal delay in conduction through the AV node (the PR interval). The “artificial” or “electronic” PR interval is referred to as an “AV interval.” If spontaneous ventricular depolarization does not occur within a preset interval, the pacemaker fires and stimulates ventricular depolarization at a preset rate.

OBJ: Explain the differences between single-chamber and dual-chamber pacemakers, and between fixed-rate and demand pacemakers.

Chapter 09: Introduction to the 12-Lead ECG Aehlert: ECGs Made Easy, 6th Edition TRUE/FALSE 1. The chest leads are the only unipolar leads in the standard 12-lead ECG. ANS: F

The augmented voltage leads and the chest leads are unipolar leads.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

2. When you read a 12-lead ECG from left to right, the ECG tracing is continuous.

ANS: T

When viewing a 12-lead ECG, leads that line up vertically are simultaneous recordings of the same beat. When you read the 12-lead ECG from left to right, the ECG tracing is continuous.

As you switch from one lead to the next, it is still continuous.

OBJ: N/A 3. Placement of right chest leads is identical to the standard chest leads except on the right side

of the chest.

ANS: T OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

4. An abnormal (i.e., pathologic) Q wave indicates the presence of dead myocardial tissue.

ANS: T

An abnormal (i.e., pathologic) Q wave is more than 0.04 seconds in duration or more than one third the height of the following R wave in that lead. Myocardial infarction is one possible cause of abnormal Q waves. In the early hours of infarction, an abnormal Q wave may not have developed to its full width or amplitude. Therefore a single ECG tracing might not identify an abnormal Q wave. In a patient with a suspected myocardial infarction, be sure to look at Q waves closely. Even if the initial ECG tracings do not show Q waves that are more than 0.04 seconds in duration or equal to or more than one third of the amplitude of the QRS complex, pathology must be considered if the Q waves become wider or deeper in each subsequent tracing.

OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

MULTIPLE CHOICE 1. Where should the positive electrode for lead V5 be positioned? a. Right side of the sternum, fourth intercostal space b. Left midaxillary line at the same level as V4

c. Left side of the sternum, fourth intercostal space d. Left anterior axillary line at the same level as V4 ANS: D

The positive electrode for lead V5 is positioned at the left anterior axillary line at the same level as V4.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

2. A standard 12-lead ECG provides views of the heart in a. the frontal plane only b. the sagittal plane only c. the horizontal plane only d. both the frontal and the horizontal planes

.

ANS: D

A standard 12-lead ECG provides views of the heart in both the frontal and horizontal planes and views the surfaces of the left ventricle from 12 different angles.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

3. Poor R-wave progression is a phrase used to describe R waves that decrease in size from V1 to

V4. This is often seen in an anteroseptal anterolateral inferolateral inferoposterior

infarction.

a. b. c. d.

ANS: A

Poor R-wave progression is a phrase used to describe R waves that decrease in size from V1 to V4. This is often seen in an anteroseptal infarction, but may be a normal variant in young persons, particularly in young women. Other causes of poor R-wave progression include left bundle branch block, left ventricular hypertrophy, and severe chronic obstructive pulmonary disease (particularly emphysema).

OBJ: Distinguish patterns of normal and abnormal R-wave progression.

4. Which leads look at adjoining tissue in the anterior region of the left ventricle? a. II, III, aVF b. V2, V3, V4 c. I, aVL, V5 d. aVR, aVL, aVF ANS: B

Leads V2, V3, and V4 look at adjoining tissue in the anterior region of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

5. Lead V1 views the . a. septum b. inferior wall of the left ventricle

c. lateral wall of the right ventricle d. anterior wall of the right ventricle ANS: A

Leads V1 and V2 view the septum.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

6. Lead aVL views the . a. interatrial septum b. lateral wall of the left ventricle c. inferior wall of the left ventricle d. anterior wall of the right ventricle ANS: B

Lead aVL views the lateral wall of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

7. Which of the following leads should be used to view the right ventricle? a. V3 b. V7 c. V4R d. V6 ANS: C

Leads V1R to V6R are used to view the right ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

8. Lead V3 views the a. lateral b. anterior c. posterior d. inferior

wall of the left ventricle.

ANS: B

Lead V3 views the anterior of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

9. Anterior or lateral wall myocardial infarctions are most often a result of an occlusion of the

coronary artery. a. left b. right ANS: A

Anterior or lateral wall myocardial infarctions are most often a result of an occlusion of the left coronary artery.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

10. Which leads look at adjoining tissue in the inferior region of the left ventricle? a. I, aVL b. V1, V2 c. V3, V4, V5 d. II, III, aVF ANS: D

Leads II, III, and aVF view adjoining tissue in the inferior region of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

11. Lead V5 views the a. lateral b. anterior c. posterior d. inferior

wall of the left ventricle.

ANS: A

Lead V5 views the lateral wall of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

12. The inferior wall of the left ventricle is supplied by the

coronary artery in most of the

population. a. left b. right ANS: B

The inferior wall of the left ventricle is supplied by the right coronary artery in most people. If an ECG shows changes in leads II, III, and aVF, the inferior wall is affected, and it is reasonable to suppose that these ECG changes are due to partial or complete blockage of the right coronary artery.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

13. Where should the positive electrode for lead V1 be positioned? a. Right side of the sternum, fourth intercostal space b. Left midaxillary line at the same level as V4 c. Left side of the sternum, fourth intercostal space d. Left anterior axillary line at the same level as V4 ANS: A

The positive electrode for lead V1 is positioned on the right side of the sternum, fourth intercostal space.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

14. Lead II views the a. anterior b. inferior

wall of the left ventricle.

c. septal d. lateral ANS: B

Lead II views the inferior wall of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

15. Which leads face the septum? a. II, aVF b. V1, V2 c. V5, V6 d. I, aVL ANS: B

Leads V1 and V2 face the septum.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

16. Which of the following ECG changes is one of the earliest to occur during an ST-elevation

infarction, but may have resolved by the time the patient seeks medical assistance?

Pathologic Q waves Hyperacute T waves Horizontal ST-segments Lengthening of the QT interval

a. b. c. d.

ANS: B

Hyperacute (i.e., tall) T waves are sometimes called tombstone T waves and typically measure more than 50% of the preceding R wave. In addition to an increase in height, the T wave becomes more symmetric and may become pointed. These changes are often not recorded on the ECG because they have typically resolved by the time the patient seeks medical assistance.

OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

17. Hypertrophy refers to a(n) . a. delay in impulse conduction through the SA node b. disturbance in impulse conduction through the AV junction c. increase in the diameter of a chamber of the heart caused by volume overload d. increase in the thickness of a heart chamber because of chronic pressure overload ANS: D

Enlargement of the atrial chambers, ventricular chambers, or both, may occur if there is a volume or pressure overload in the heart. Dilatation is an increase in the diameter of a chamber of the heart caused by volume overload. Dilatation may be acute or chronic.

Hypertrophy is an increase in the thickness of a heart chamber because of chronic pressure overload. Hypertrophy is commonly accompanied by dilatation. Enlargement is a term that implies the presence of dilatation or hypertrophy or both.

OBJ: Explain what is meant by the terms dilatation, hypertrophy, and enlargement.

18. Patients who experience a(n)

myocardial infarction have a greater incidence of heart failure and cardiogenic shock than those who have myocardial infarctions affecting other areas of the left ventricle. a. lateral b. posterior c. inferior d. anterior ANS: D

Because the left anterior descending artery supplies approximately 40% of the heart’s blood and a critical section of the left ventricle, a blockage in this area can lead to left ventricular dysfunction, including heart failure and cardiogenic shock.

OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

19. An ECG machine’s sensitivity must be calibrated so that a 1-millivolt electrical signal will

produce a deflection measuring exactly 0.5 1 5 10

mm tall.

a. b. c. d.

ANS: D

When evaluating the ECG for the presence of chamber enlargement, it is particularly important to check the calibration marker to ensure that it is 10-mm tall.

OBJ: N/A 20. Normal electrical axis lies between a. –30 and +90 b. +90 and +180 c. –91 and –180 d. –1 and –90

degrees.

ANS: A

In adults, the normal QRS axis is considered to be between –30 degrees and +90 degrees in the frontal plane.

OBJ: Explain the term electrical axis and its significance.

21. Lead I is perpendicular to lead a. II b. III c. aVF d. aVL

.

ANS: C

In the hexaxial reference system, the axes of some leads are perpendicular to each other. Lead I is perpendicular to lead aVF. Lead II is perpendicular to aVL, and lead III is perpendicular to lead aVR.

OBJ: Discuss the determination of electrical axis using leads I and aVF. 22. Lead I views the . a. septum b. inferior wall of the left ventricle c. lateral wall of the left ventricle d. anterior wall of the right ventricle ANS: C

Lead I views the lateral wall of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

23. Indicative ECG changes observed in leads V1, V2, V3, and V4 suggest that the

the a. b. c. d.

wall of

ventricle is affected. posterior; right anteroseptal; left inferolateral; left anterolateral; right

ANS: B

Leads V1 and V2 view the septum. Leads V3 and V4 view the anterior wall of the left ventricle; therefore indicative ECG changes observed in these leads suggest that the anteroseptal areas of the left ventricle are affected.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

COMPLETION 1. The coronary arteries originate at the base of the

.

ANS: aorta OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

2. When reviewing a 12-lead ECG, intervals and duration are usually expressed in

.

ANS: milliseconds OBJ: N/A 3. The axes of leads I, II, and III form an equilateral triangle with the heart at the center

(Einthoven's triangle). If the augmented limb leads are added to this configuration and the axes of the six leads moved in a way in which they bisect each other, the result is the .

ANS: hexaxial reference system OBJ: Explain the term electrical axis and its significance.

SHORT ANSWER 1. List six leads that view the heart in the frontal plane.

ANS:

Frontal plane leads view the heart from the front of the body as if it were flat. Directions in the frontal plane are superior, inferior, right, and left. Six leads view the heart in the frontal plane.

Leads I, II, and III are called standard limb leads. Leads aVR, aVL, and aVF are called augmented limb leads.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

2. Acute coronary syndromes consist of three major syndromes that are related. List the three

syndromes.

ANS:

Unstable angina, non–ST-segment elevation myocardial infarction, and ST-segment elevation myocardial infarction OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

3. Explain the meaning of the letters in aVR, aVL, and aVF. ANS:

The a in aVR, aVL, and aVF refers to augmented. The V refers to voltage. The R refers to right arm, the L to left arm, and the F to foot (usually of the left leg). The position of the positive electrode corresponds to the last letter in each of these leads. The positive pole in aVR is located on the right arm, aVL has a positive pole at the left arm, and aVF has a positive electrode positioned on the left leg.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

4. Describe the appearance of a pathologic Q wave.

ANS:

An abnormal (pathologic) Q wave is more than 40 ms (0.04 seconds) in duration and equal to or more than one third of the amplitude of the following R wave in that lead. A pathologic Q wave is suggestive of infarction.

OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

5. List the ECG leads that view the heart in the horizontal plane, allowing a view of the front and

left side of the heart.

ANS:

Six chest leads view the heart in the horizontal plane, allowing a view of the front and left side of the heart. The chest leads are identified as V1, V2, V3, V4, V5, and V6.

OBJ: Differentiate between the frontal plane and the horizontal plane leads.

6. What two factors determine the portion of the heart that each lead “sees”?

ANS:

The particular portion of the heart that each lead “sees” is determined by two factors. The first factor is the dominance of the left ventricle on the ECG and the second is the position of the positive electrode on the body.

OBJ: N/A

Chapter 10: Post-Test Aehlert: ECGs Made Easy, 6th Edition TRUE/FALSE 1. The term acute coronary syndromes refers to patients presenting with ischemic chest pain.

ANS: T

Acute coronary syndrome (ACS) is a term used to refer to distinct conditions caused by a similar sequence of pathologic events—a temporary or permanent blockage of a coronary artery. These conditions are characterized by an excessive demand or inadequate supply of oxygen and nutrients to the heart muscle associated with plaque disruption, thrombus formation, and vasoconstriction. ACSs consist of three major syndromes: unstable angina (UA), non–ST-segment elevation myocardial infarction (NSTEMI), and ST segment elevation myocardial infarction (STEMI).

OBJ: Define and explain acute coronary syndromes.

2. In the limb leads, the ST-segment is normally isoelectric.

ANS: T

The normal ST segment begins at the isoelectric line, extends from the end of the S wave, and curves gradually upward to the beginning of the T wave. In the limb leads, the normal ST segment is isoelectric (flat), but may normally be slightly elevated or depressed.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

3. A Q wave, if present, is always a negative waveform.

ANS: T

The QRS complex begins as a downward deflection, the Q wave. A Q wave is always a negative waveform. The Q wave begins when the ECG leaves the isoelectric line in a downward direction and continues until it returns to the isoelectric line. The Q wave represents depolarization of the interventricular septum, which is activated from left to right.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

4. The point where the QRS complex and ST segment meet is called the ST junction or the J

point.

ANS: T

The point where the QRS complex and the ST segment meet is called the ST junction or the J point. The ST segment is considered elevated if the segment is deviated above the baseline and is considered depressed if the segment deviates below it.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical

activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

5. The term ectopic refers to an extra muscle bundle consisting of working myocardial tissue that

forms a connection between the atria and ventricles outside the normal conduction system.

ANS: F

The term ectopic, which means out of place, is used to describe an impulse that originates from a source other than the SA node. Ectopic pacemaker sites include the cells of the AV bundle and Purkinje fibers, although their intrinsic rates are slower than that of the SA node.

OBJ: N/A 6. The six limb leads view the heart in the frontal plane as if the body were flat.

ANS: T

Frontal plane leads view the heart from the front of the body as if it were flat. Directions in the frontal plane are superior, inferior, right, and left. Six leads view the heart in the frontal plane.

Leads I, II, and III are called standard limb leads. Leads aVR, aVL, and aVF are called augmented limb leads.

OBJ: Differentiate between the frontal plane and the horizontal plane leads.

7. Individuals with preexcitation syndrome are predisposed to tachydysrhythmias.

ANS: T

Unlike the AV node, an accessory pathway does not have the ability to slow or reduce the number of atrial impulses transmitted to the ventricles; therefore, patients with preexcitation syndromes are prone to tachydysrhythmias, including atrioventricular reentrant tachycardia and atrial fibrillation.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia.

8. The electrocardiogram (ECG) is a reflection of the heart’s mechanical activity.

ANS: F

The ECG is a graphic display of the heart’s electrical activity. The ECG can provide information about the orientation of the heart in the chest, conduction disturbances, the electrical effects of medications and electrolytes, the mass of cardiac muscle, and the presence of ischemic damage. The ECG does not provide information about the mechanical (contractile) condition of the myocardium. To evaluate the effectiveness of the heart’s mechanical activity, the patient’s pulse and blood pressure are assessed.

OBJ: Identify the limitations of the electrocardiogram.

9. Cardiac output is the amount of blood pumped into the aorta each minute by the heart.

ANS: T

Cardiac output is the amount of blood pumped into the aorta each minute by the heart. It is defined as the stroke volume multiplied by the heart rate.

OBJ: Identify and explain the components of blood pressure and cardiac output.

10. A delay or block that occurs in one of the bundle branches affects ventricular depolarization.

ANS: T

If a delay or block occurs in one of the bundle branches, the ventricles will not be depolarized at the same time. The electrical impulse travels first down the unblocked branch and stimulates that ventricle. Because of the block, the impulse must then travel from cell to cell through the myocardium, rather than through the normal conduction pathway, to stimulate the other ventricle. The ventricle with the blocked bundle branch is the last to be depolarized.

OBJ: Describe the appearance of right and left bundle branch block as seen in lead V1.

11. Leads V4R, V5R, and V6R are used to view the posterior wall of the left ventricle.

ANS: F

Leads V4R, V5R, and V6R view the right ventricle. The leads corresponding to the posterior wall of the left ventricle are V7, V8, and V9.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

12. In most ECG leads, a normal Q wave is less than 0.04 seconds in duration and less than one-

third of the amplitude of the R wave in that lead.

ANS: T

With the exception of leads III and aVR, a normal Q wave in the limb leads is less than 0.04 seconds in duration and less than one third of the amplitude of the R wave in that lead.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

13. Depolarization is the same as contraction.

ANS: F

Depolarization is not the same as contraction. Depolarization is an electrical event that is expected to result in contraction, which is a mechanical event. It is possible to see organized electrical activity on the cardiac monitor, even when the assessment of the patient reveals no palpable pulse. This clinical situation is called pulseless electrical activity (PEA).

OBJ: Define the terms membrane potential, threshold potential, action potential, polarization, depolarization, and repolarization.

14. Proper positioning of the electrodes for leads I, II, and III requires placement on the patient’s

torso.

ANS: F

Leads I, II, III, aVR, aVL, and aVF are obtained from electrodes placed on the patient’s arms and legs. The deltoid area is suitable for electrodes attached to the arms and is easily accessible. Either the thigh or lower leg is suitable for the leg electrodes. Use the more convenient site, but keep the electrodes in a similar position. For example, keep the upper extremity electrodes on the deltoids, not one on the upper arm, and one on the inner arm. Be sure that the patient’s limbs are resting on a supportive surface. This decreases muscle tension in the patient’s arms and legs and helps minimize distortion of the ECG tracing (i.e., artifact).

Should circumstances require that the leads be placed on the torso, be certain to position them as close to the appropriate limb as possible.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

15. A macroreentrant circuit is one that involves a small area of heart tissue, usually a few

centimeters or less.

ANS: F

Macroreentry circuits and microreentry circuits are two main types of reentry circuits. If the reentry circuit involves conduction through a large area of the heart, such as the entire right or left atrium, it is called a macroreentry circuit. A reentry circuit involving conduction within a small area is called a microreentry circuit.

OBJ: Describe reentry.

MULTIPLE CHOICE 1. The inferior surface of the left ventricle is supplied by the

coronary artery in most of

the population. a. left b. right ANS: B

A branch of the RCA supplies the inferior surface of the left ventricle in approximately 85% of individuals.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

2. The

originate from small mounds of myocardium called papillary muscles and serve as anchors to prevent the cusps of the AV valves from inverting into the atria. a. Purkinje fibers b. coronary sinuses c. coronary arteries d. chordae tendineae ANS: D

Chordae tendineae are thin strands of connective tissue. On one end, they are attached to the underside of the AV valves. On the other end, they are attached to small mounds of myocardium called papillary muscles. Papillary muscles project inward from the lower portion of the ventricular walls. When the ventricles contract and relax, so do the papillary muscles. The papillary muscles adjust their tension on the chordae tendineae, preventing them from bulging too far into the atria.

OBJ: Describe the structure and function of the coverings of the heart.

3. Which of the following correctly reflects the ECG indicators of ischemia? a. Pathologic Q waves, ST-segment elevation b. ST-segment elevation, T wave inversion c. ST-segment depression, T wave inversion d. Pathologic Q waves, ST-segment depression ANS: C

In a patient experiencing an acute coronary syndrome, T wave inversion, which can occur simultaneously with ST-segment elevation, suggests the presence of myocardial ischemia. The development of pathologic Q waves provides evidence that tissue death has occurred. A pathologic Q wave indicates the presence of dead myocardial tissue and subsequently, a loss of electrical activity.

OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

4. Two conditions must exist to suspect bundle branch block. First, the QRS complex must have

an abnormal duration (0.12 seconds or more in width), and second . an RSR’ complex must be seen in leads V1-V6 a QS pattern must be seen in leads I, II, and III a slurred upstroke of the QRS complex must exist the QRS complex must arise as the result of supraventricular activity

a. b. c. d.

ANS: D

Essentially two conditions must exist to suspect bundle branch block. First, the QRS complex must have an abnormal duration (i.e., 0.12 seconds or more in width if a complete BBB).

Second, the QRS complex must arise as the result of supraventricular activity, excluding ventricular beats. If these two conditions are met, delayed ventricular conduction is assumed to be present, and bundle branch block is the most common cause of this abnormal conduction.

OBJ: Describe the appearance of right and left bundle branch block as seen in lead V1.

5. The left atrium receives blood from the a. aorta b. pulmonary veins c. pulmonary arteries d. inferior vena cava

.

ANS: B

The left atrium receives freshly oxygenated blood from the lungs via the right and left pulmonary veins.

OBJ: Beginning with the right atrium, describe blood flow through the normal heart and lungs to the systemic circulation.

6. In an adult, the normal duration of the QRS complex is a. 0.12 to 0.20 b. 0.06 to 0.11 c. 0.04 to 0.14 d. 0.20 to 0.38

seconds.

ANS: B

The beginning of the QRS is measured from the point where the first wave of the complex begins to deviate from the baseline. The point at which the last wave of the complex begins to level out at, above, or below the baseline marks the end of the QRS complex. The QRS is considered narrow (i.e., normal) if it measures 0.11 seconds or less; it is considered wide if it measures more than 0.11 seconds. A QRS complex of 0.11 seconds or less (i.e., narrow) is presumed to be supraventricular in origin.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

7. Where is the positive electrode placed in lead III? a. Right arm b. Left arm c. Left leg or foot d. Right leg or foot ANS: C

Lead III records the difference in electrical potential between the left leg (+) and left arm (–) electrodes. In lead III, the positive electrode is placed on the left leg and the negative electrode is placed on the left arm.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

8. Signs and symptoms experienced during a tachydysrhythmia are usually primarily related to a. b. c. d.

. atrial irritability vasoconstriction slowed conduction through the AV node decreased ventricular filling time and stroke volume

ANS: D

In a patient with coronary artery disease, sinus tachycardia can cause problems. The heart’s demand for oxygen increases as the heart rate increases. As the heart rate increases, there is less time for the ventricles to fill and less blood for the ventricles to pump out with each contraction, which can lead to decreased cardiac output. Because the coronary arteries fill when the ventricles are at rest, rapid heart rates decrease the time available for coronary artery filling. This decreases the heart’s blood supply. Chest discomfort can result if the supplies of blood and oxygen to the heart are inadequate.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and emergency management of sinus tachycardia.

9. In a junctional rhythm viewed in lead II, where is the location of the P wave on the ECG if

ventricular depolarization precedes atrial depolarization? a. Before the QRS complex b. During the QRS complex c. After the QRS complex ANS: C

If the AV junction paces the heart, the electrical impulse must travel in a backward (retrograde) direction to activate the atria. If the atria depolarize before the ventricles, an inverted P wave will be seen before the QRS complex and the PR interval will usually measure 0.12 seconds or less. The PR interval is shorter than usual because an impulse that begins in the AV junction does not have to travel as far to stimulate the ventricles. If the atria and ventricles depolarize at the same time, a P wave will not be visible because it will be hidden in the QRS complex. When the atria are depolarized after the ventricles, the P wave typically distorts the end of the QRS complex and an inverted P wave will appear after the QRS. OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

10. Anterior wall myocardial infarctions are most often a result of an occlusion of a branch of the

coronary artery. a. left b. right ANS: A

Anterior myocardial infarctions are usually the result of an occlusion of the diagonal branch of the left anterior descending coronary artery, which is a branch of the left coronary artery.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

11. Which side of the heart is a high-pressure system that pumps arterial blood to the systemic

circulation? a. Left b. Right ANS: A

The job of the left heart is to receive oxygenated blood from the lungs and pump it out to the rest of the body (i.e., the systemic circulation). The left side of the heart is a high-pressure pump. The pressure within the left atrium is normally between 8 and 12 mm Hg. Blood is carried from the heart to the organs of the body through arteries, arterioles, and capillaries.

Blood is returned to the right heart through venules and veins.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

12. On an ECG, what is the first negative deflection seen after the P wave? a. Q wave b. R wave

c. S wave d. T wave ANS: A

The Q wave is the first negative deflection seen after the P wave.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

13.

is a term used to describe the period of recovery that cells need after being discharged before they are able to respond to a stimulus. a. Irritability b. Polarization c. Conductivity d. Refractoriness ANS: D

Refractoriness is a term used to describe the period of recovery that cells need after being discharged before they are able to respond to a stimulus.

OBJ: Define the absolute, effective, relative refractory, and supranormal periods and their location in the cardiac cycle.

14. Which of the following are chest leads? a. Leads I and aVL b. Leads I, II, and III c. Leads V1, V2, V3, V4, V5, V6 d. Leads I, II, III, aVR, aVL, and aVF ANS: C

The chest leads are identified as V1, V2, V3, V4, V5, and V6. Each electrode placed in a V position is a positive electrode, measuring electrical potential with respect to the Wilson Central Terminal.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

15. Which of the following correctly describes multifocal atrial tachycardia? a. The atrial rhythm is regular. b. The ventricular rhythm is irregular. c. The atrial and ventricular rhythms are regular. d. The atrial and ventricular rhythms are irregular.

ANS: D

With multifocal atrial tachycardia, the atrial and ventricular rhythms are usually irregular as the pacemaker site shifts from the SA node to ectopic atrial locations or AV junction.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for multifocal atrial tachycardia.

16. Atrial fibrillation is characterized by

.

a. b. c. d.

an erratic, wavy baseline and irregular ventricular rhythm “saw-tooth”– or “picket-fence”–shaped waveforms preceding each QRS one P wave before each QRS and a regular ventricular rate of 60 to 100 beats/min P waves occurring before, during, or after the QRS complex; when seen, they are inverted

ANS: A

Atrial fibrillation (AFib) is characterized by an erratic, wavy baseline and an irregularly irregular ventricular rhythm. Because of the quivering of the atrial muscle and because there is no uniform wave of atrial depolarization in AFib, there is no P wave. Instead, you see wavy deflections that are called “fibrillatory waves.”

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrial fibrillation.

17. A delta wave is an ECG characteristic associated with which of the following dysrhythmias? a. Junctional rhythm b. AV nodal reentrant tachycardia (AVNRT) c. Wolff-Parkinson-White (WPW) syndrome d. Accelerated idioventricular rhythm (AIVR) ANS: C

Characteristic ECG findings in Wolff-Parkinson-White syndrome include a short PR interval, QRS widening, and a delta wave. A delta wave is an initial slurred deflection at the beginning of the QRS complex that results from the initial activation of the QRS by conduction over the accessory pathway.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular reentrant tachycardia.

18. Which of the following leads are anatomically contiguous? a. II, V2 b. II, III, V3 c. I, V3, V4 d. V2, V3, V4 ANS: D

Two leads are contiguous if they look at the same or adjacent areas of the heart or they are numerically consecutive chest leads. Leads V2, V3, V4 are numerically consecutive chest leads.

OBJ: N/A 19. The myocardium is thickest in the a. left atrium b. right atrium c. left ventricle d. right ventricle

.

ANS: C

The wall of the left ventricle is threefold thicker than that of the right because the left ventricle propels blood to most vessels of the body. The right ventricle moves blood only through the blood vessels of the lungs and then into the left atrium.

OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

20. An ECG machine’s sensitivity must be calibrated so that a 1-mV electrical signal will produce

a deflection measuring exactly 0.5 1 5 10

-mm tall.

a. b. c. d.

ANS: D

The ECG machine’s sensitivity must be calibrated so that a 1-mV electrical signal will produce a deflection that measures exactly 10-mm tall. When properly calibrated, a small box is 1-mm high (i.e., 0.1 mV), and a large box, which is equal to five small boxes, is 5 mm high (i.e., 0.5 mV).

OBJ: N/A 21. The first segment of the left coronary artery is the a. circumflex b. right coronary c. left main coronary d. left anterior descending

artery.

ANS: C

The first segment of the left coronary artery is called the left main coronary artery. It is about the width of a soda straw and less than 1 inch long. Blockage of the left main coronary artery has been referred to as the widow maker because of its association with sudden cardiac arrest when occluded.

OBJ: Name the primary branches and areas of the heart supplied by the right and left coronary arteries.

22. Tall, peaked T waves observed on the ECG are most commonly seen in patients with a. hypokalemia b. hyponatremia c. hyperkalemia d. hypernatremia

.

ANS: C

Tall, pointed (i.e., peaked) T waves are commonly seen in hyperkalemia.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

23. The anterior surface of the heart consists primarily of the a. left atrium b. right atrium c. left ventricle d. right ventricle

.

ANS: D

The front (anterior) surface of the heart lies behind the sternum and costal cartilages. It is formed by portions of the right atrium and the left and right ventricles. However, because the heart is tilted slightly toward the left in the chest, the right ventricle is the area of the heart that lies most directly behind the sternum.

OBJ: Identify the surfaces of the heart.

24. Which of the following are chest leads? a. Leads I, II, and III b. Leads I and aVL c. Leads V1, V2, V3, V4, V5, and V6 d. Leads I, II, III, aVR, aVL, and aVF ANS: C

The chest leads are identified as V1, V2, V3, V4, V5, and V6.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

25. How are frequent PACs usually managed? a. Defibrillation b. Synchronized cardioversion c. Correcting the underlying cause d. Administration of medications such as atropine or epinephrine ANS: C

Frequent PACs are treated by correcting the underlying cause. For example, correcting electrolyte imbalances, reducing stress, reducing or eliminating stimulants, and treating heart failure.

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes.

26. Myocardial ischemia delays the process of repolarization; therefore the ECG changes

characteristic of ischemia include . widening of the QRS complex prolongation of the PR interval changes in the ST segment and T wave changes in the QRS complex and ST segment

a. b. c. d.

ANS: C

Myocardial ischemia delays the process of repolarization; therefore the ECG changes characteristic of ischemia include changes in the ST segment and T wave.

OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

27. Lead III views the a. septal b. inferior c. posterior

wall of the left ventricle.

d. lateral ANS: B

Lead III views the inferior wall of the left ventricle.

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

COMPLETION 1. A

bundle branch block produces a QS pattern in lead V1.

ANS: left OBJ: Describe the appearance of right and left bundle branch block as seen in lead V1.

2. When reviewing a 12-lead ECG, intervals and duration are usually expressed in

.

ANS: milliseconds OBJ: Describe a systematic method for analyzing a 12-lead ECG. 3. If the AV junction paces the heart, the electrical impulse must travel in a backward direction to

activate the atria. This is called

conduction.

ANS: retrograde OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for a junctional escape rhythm.

4. A beat originating from the AV junction that appears later than the next expected sinus beat is

called a(n)

.

ANS: junctional escape beat OBJ: Describe the ECG characteristics and possible causes for junctional escape beats.

5. The right atrium receives deoxygenated blood from the

(which carries blood from the head and upper extremities), the (which carries blood from the lower body), and the (which receives blood from the intracardiac circulation).

ANS: superior vena cava; inferior vena cava; coronary sinus OBJ: Identify and describe the chambers of the heart and the vessels that enter or leave each.

6. Sometimes, when a premature atrial complex (PAC) occurs very prematurely and close to the

T wave of the preceding beat, only a P wave may be seen with no QRS after it (appearing as a pause). This type of PAC is termed a(n) PAC. ANS: nonconducted or blocked

OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for premature atrial complexes.

7. An accessory pathway that has one end attached to normal conductive tissue is called a(n)

.

ANS: bypass tract OBJ: Describe the ECG characteristics, possible causes, signs and symptoms, and initial emergency care for atrioventricular nodal reentrant tachycardia.

8. Each small box on ECG paper represents

seconds.

ANS: 0.04 OBJ: Identify the numeric values assigned to the small and to the large boxes on ECG paper.

9. The axes of leads I, II, and III form an equilateral triangle with the heart at the center

(Einthoven’s triangle). If the augmented limb leads are added to this configuration and the axes of the six leads moved in a way in which they bisect each other, the result is the .

ANS: hexaxial reference system OBJ: Explain the term electrical axis and its significance.

10. A QRS measuring 0.10 to 0.12 seconds is called a(n)

right or left bundle branch block.

ANS: incomplete OBJ: Describe the appearance of right and left bundle branch block as seen in lead V1.

11. The area supplied by an obstructed coronary artery goes through a characteristic sequence of

events that have been identified as zones of

,

, and

.

ANS: ischemia; injury; infarction OBJ: Recognize the changes on the ECG that may reflect evidence of myocardial ischemia, injury, or infarction.

12. A(n)

is a vertical line on the ECG that indicates the pacemaker has discharged.

ANS: pacemaker spike OBJ: Describe the appearance of a typical pacemaker spike on the ECG. 13. A(n)

occurs as a result of an electrical impulse from a supraventricular site (such as the SA node) discharging at the same time as an ectopic site in the ventricles.

ANS: fusion beat OBJ: N/A

SHORT ANSWER 1. Indicate the heart surface viewed by each of the following:

Leads II, III, aVF Leads V1, V2 Leads V3, V4 Leads I, aVL, V5, V6 ANS:

Leads II, III, aVF V1, V2 V3, V4 I, aVL, V5, V6

Heart Surface Viewed Inferior Septal Anterior Lateral

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

2. Complete the following:

Lead V1 V2 V3 V4 V5 V6

Heart Surface Viewed

ANS:

Lead V1 V2 V3 V4 V5 V6

Heart Surface Viewed Septum Septum Anterior Anterior Lateral Lateral

OBJ: Relate the cardiac surfaces or areas represented by the ECG leads.

3. Indicate the inherent rates for each of the following pacemaker sites:

Sinoatrial (SA) node Atrioventricular (AV) junction Ventricles ANS:

SA node: AV junction:

60 to 100 beats/min 40 to 60 beats/min

Ventricles:

20 to 40 beats/min

OBJ: Describe the location, function, and, where appropriate, the intrinsic rate of the following structures: the sinoatrial (SA) node, the atrioventricular (AV) bundle, and the Purkinje fibers.

4. Explain the difference between a PVC and a ventricular escape beat.

ANS:

A PVC is premature and occurs before the next expected sinus beat. A ventricular escape beat is late, occurring after the next expected sinus beat.

OBJ: Explain the difference between PVCs and ventricular escape beats.

5. Describe the appearance of a pathologic Q wave.

ANS:

An abnormal (i.e., pathologic) Q wave is more than 0.04 seconds in duration or more than one third the height of the following R wave in that lead. Myocardial infarction is one possible cause of abnormal Q waves.

OBJ: Define and describe the significance of each of the following as they relate to cardiac electrical activity: the P wave, the QRS complex, the T wave, the U wave, the PR segment, the TP segment, the ST segment, the PR interval, the QRS duration, and the QT interval.

6. When is the term intraventricular conduction delay used?

ANS:

A QRS measuring 0.10 to 0.12 seconds is called an incomplete right or left bundle branch block (BBB). A QRS measuring more than 0.12 seconds is called a complete right or left bundle branch block. If the QRS is wide but there is no BBB pattern, the term wide QRS or intraventricular conduction delay is used to describe the QRS. OBJ: N/A 7. Explain the benefits of a dual-chamber pacemaker.

ANS:

A dual-chamber pacemaker stimulates the right atrium and right ventricle sequentially (stimulating first the atrium, then the ventricle), mimicking normal cardiac physiology and thus preserving the atrial contribution to ventricular filling (atrial kick).

OBJ: Explain the differences between single-chamber and dual-chamber pacemakers, and between fixed-rate and demand pacemakers.

8. Explain the meaning of the letters in aVR, aVL, and aVF. ANS:

The a in aVR, aVL, and aVF refers to augmented. The V refers to voltage. The R refers to right arm, the L to left arm, and the F to left foot (leg). The position of the positive electrode corresponds to the last letter in each of these leads. The positive pole in aVR is located on the right arm, aVL has a positive pole at the left arm, and aVF has a positive electrode positioned on the left leg.

OBJ: Describe correct anatomic placement of the standard limb leads, the augmented leads, and the chest leads.

9. What is a biphasic waveform?

ANS:

A biphasic waveform is partly positive and partly negative and is recorded when the wave of depolarization moves perpendicularly to the positive electrode.

OBJ: N/A 10. Your patient has a VVI pacemaker. Briefly explain the meaning of each of these letters.

ANS:

A ventricular demand (VVI) pacemaker is a common type of pacemaker. With this device, the pacemaker electrode is placed in the right ventricle (V); the ventricle is sensed (V) and the pacemaker is inhibited (I) when spontaneous ventricular depolarization occurs within a preset interval. When spontaneous ventricular depolarization does not occur within this preset interval, the pacemaker fires and stimulates ventricular depolarization at a preset rate.

OBJ: Describe how to analyze pacemaker function on the ECG. 11. List five signs or symptoms of decreased cardiac output.

ANS:

Signs and symptoms of decreased cardiac output: acute changes in blood pressure; acute changes in mental status; cold, clammy skin; color changes in the skin and mucous membranes; crackles (rales); dyspnea; dysrhythmias; fatigue; orthopnea; restlessness OBJ: Identify and explain the components of blood pressure and cardiac output.