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PAU-CD6-CTP

ULTRA P.A.S.S. Adult Echocardiography Workbook Includes U/S Technology and Physics! Now with pathology DVD companion! Written by: Patrick Coon, RDCS, RVT, FASE Edited by Lori Green, BA, RT(R), RDMS, RDCS, RVT and Lowell “Corky” Hecht, BA, RDMS, RDCS, RVT, RT(N)

A comprehensive review book for the ultrasound registry

New! Interactive DVD companion 87 pathology clips and animations!

Content based on ARDMS outline 6 Audio CDs narrate text Chapter quizzes included... 301 Self-Assessment questions!

20.0 AMA Cat.1 PRA CME available


Table of Contents SECTION 1: ANATOMY AND PHYSIOLOGY .........................................11 Ventricular Wall Segments ................................................................... 13 Nomenclature ........................................................................................ 14 Right Ventricle ....................................................................................... 16 Great Vessels......................................................................................... 18 Coronary Arteries.................................................................................. 20 Coronary Veins...................................................................................... 20 Phases of the Cardiac Cycle ................................................................ 21 Propagation of Electrical Activity ........................................................ 22 Mechanical Considerations and Events.............................................. 23 Frank Starling Law (length-tension relationship) ......................................................... 23 Force-Velocity Relationship............................................................................................ 23 Interval-Strength Relationship........................................................................................ 24 Valve Opening and Closure ............................................................................................ 24

Phases of the Cardiac Cycle (Electromechanical Events) ................ 24 Left Ventricular Function: Indicators and Normal Values ................. 25 Pulmonary vs. Systemic Circulation: Differences and Similarities .. 25 Pressure............................................................................................................................ 26 Oxygen Content ............................................................................................................... 26 Volumes ............................................................................................................................ 26

Intracardiac Pressures and Principles of Flow .................................. 26 Maneuvers Altering Cardiac Physiology............................................. 27 Normal Heart Sound Generation and Timing ..................................... 27 Cardiovascular Circulation................................................................... 28 CARDIAC HEMODYNAMICS................................................................. 29 Factors affecting blood flow ........................................................................................... 29 Characteristics and Types .............................................................................................. 30 Laminar Flow .................................................................................................................... 30 Disturbed flow .................................................................................................................. 30

Effects of Abnormal Pressures and Loading, Volume Concepts ..... 31 Heart failure and shock ................................................................................................... 31 Valvular stenosis.............................................................................................................. 31 Valvular regurgitation ...................................................................................................... 31 Shunts ............................................................................................................................... 31 Pulmonary disease .......................................................................................................... 31 Pericardial disease........................................................................................................... 31 Cardiomyopathies............................................................................................................ 32 Pulmonary Veins .............................................................................................................. 32

ANATOMY AND PHYSIOLOGY QUIZ ................................................... 35 SECTION 2: TECHNIQUE........................................................................41 Use of Equipment Controls .................................................................. 43 3


SYSTEMIC and PULMONARY HYPERTENSIVE HEART DISEASE Systemic Hypertension occurs when the blood pressure rises higher than normal. There are no fixed rules regarding what is considered a normal blood pressure. According to the American Heart Association guidelines, a blood pressure reading that has been taken several times and on various occasions greater than 140/90 is considered abnormal while 120/75 is considered “prehypertensive�.

Apical Four Chamber LVH

There are multiple conditions that may cause hypertension, but the primary factor is increased peripheral resistance that results from vasoconstriction or narrowing of the peripheral vessels. Less common causes may be coarctation of the aorta, or pheochromocytoma. The most common response of the heart to chronic hypertension is left ventricular hypertrophy. Left ventricular systolic function tends to be hyperdynamic, possibly causing a dynamic left ventricular outflow tract obstruction. Other cardiac findings associated with hypertensive heart disease include aortic valve sclerosis, dilatation of the aortic root, mitral annular calcification, left atrial enlargement, and atrial fibrillation.

Video Clip 5-A. Apical 4 chamber LVH

Parasternal Long Axis LVH & Annular Calcification

149


velocity, prolonged left ventricle isovolumic relaxation time, and prolonged mitral inflow deceleration time. In the event that congestive heart failure develops, or a hypertensive crisis occurs, the diastolic filling pattern may become restrictive, or pseudonormalized.

Video Clip 5-B. PLAX LVH & MAC

Reversal of E to A Inflow Velocity

When hypertrophy is present in a patient due to physical conditioning, abnormal E to A velocities are not usually seen. The following parameters should be used for the echocardiographic assessment of systemic hypertension. PSA M-mode Left Ventricular Hypertrophy

Assessment of Systemic Hypertension • • • • • • •

Left ventricular mass index Left ventricle cavity dimensions Left ventricle wall dimensions Left ventricle systolic function Left ventricle diastolic function Evaluation of LVOT to rule out obstruction Evaluation of the aorta for dissection, aneurysm and/or coarctation

The methods commonly used to determine left ventricular systolic and diastolic function are discussed in chapter seven.

Video Clip 5-C. PSAX M-mode LVH

Left ventricular diastolic function may also be compromised in patients with chronic hypertension due to abnormal relaxation of the cardiac muscle. Doppler indications of left ventricular diastolic dysfunction include reversal of the left ventricle E to A inflow 150


Patent Ductus Arteriosus is the persistence of the communication between the aorta and the main pulmonary artery.

Transposition of the great arteries is an abnormal connection of the aorta and pulmonary artery to their respective ventricles.

AO

Patent foramen ovale is the continued patency of the fossa ovales resulting in communication of blood flow between the right and left atrium.

PA

Valvular Anomalies

LA LA

RA

Congenital heart defects can be primarily valvular in origin, as well as in combination with the cardiac defects mentioned previously. Valvular abnormalities in the newborn can take one of four forms. The diseased valve may be atretic meaning missing altogether, it may be hypoplastic or underdeveloped, it may be intrinsically stenotic, or it may have some malformation of its leaflets which cause it to be regurgitant, stenotic, or both.

LV RV

Transposition of the great arteries

Truncus Arteriosus involves a defect where the aorta and pulmonary artery fail to separate from their common origin and result in a single vessel being fed from both ventricles.

A Bicuspid aortic valve is one of the most common congenital heart defects. The normal aortic valve has three cusps. In this congenital defect, the aortic valve has two cusps. Bicuspid aortic valves tend to become stenotic,but can be regurgitant. Bicuspid valves are at a much greater risk of developing endocarditis. Other common forms of congenital valvular heart disease include: tricuspid atresia, truncus arteriosus, a situation with a common semilunar valve, and pulmonary atresia.

Truncus LA LA

RA

LV RV

Less common, but of note is Ebstein’s anomaly and cleft mitral valve. Ebstein’s anomaly is the apical displacement of the septal and posterior leaflets of the tricuspid valve. It results in the atrialization of the proximal portion of the right ventricle. It is a cyanotic heart lesion and is associated with right ventricular conduction delays, right ventricular bundle branch block, and WolfParkinson-White syndrome.

Truncus arteriosus

Persistence of Normal Fetal Communication There are two main types of defects caused by persistent fetal circulation in the natal state: patent ductus arteriosus, and patent foramen ovale. 231


PAU-CD1-PHYS

ULTRA P.A.S.S. Ultrasound Physics & Instrumentation Now with video animations on DVD! Written by Lowell “Corky” Hecht, BA, RDMS, RDCS, RVT, RT(N) Edited by Lori Green, BA, RDMS, RDCS, RVT, RT(R)

A comprehensive review book for the ultrasound registry

New! Interactive DVD companion Content based on ARDMS outline Audio CDs narrate text Chapter quizzes included 17.0 AMA PRA Cat.1 CME Credits™ available


Table of Contents SECTION 1: ELEMENTARY PRINCIPLES .......................................................................... 9 NATURE OF ULTRASOUND............................................................................................................................11 Definition of sound ......................................................................................................................................11 Propagation of vibration..............................................................................................................................11 Compression and Rarefaction ....................................................................................................................11 Audible vs. Ultrasound ................................................................................................................................12 FREQUENCY, WAVELENGTH & PROPAGATION SPEED ............................................................................12 PROPERTIES OF ULTRASOUND WAVES .....................................................................................................14 Amplitude .....................................................................................................................................................14 Pressure........................................................................................................................................................14 Power ............................................................................................................................................................14 Intensity ........................................................................................................................................................15 DECIBLES ........................................................................................................................................................15 PHYSICAL UNITS.............................................................................................................................................16 Scientific notation........................................................................................................................................16 MEASUREMENT DIMENSIONS.......................................................................................................................16 Distance ........................................................................................................................................................16 Circumference..............................................................................................................................................16 Area ...............................................................................................................................................................17 Volume ..........................................................................................................................................................17 Elementary Principles Section Quiz ..............................................................................................................19

SECTION 2: PROPAGATION OF ULTRASOUND THROUGH TISSUES ......................... 23 SPEED OF SOUND ..........................................................................................................................................25 Average speed of sound in tissue..............................................................................................................25 Range of propagation speeds in body.......................................................................................................25 REFLECTION....................................................................................................................................................25 Characteristics of Acoustic Impedance .....................................................................................................25 Reflection and transmission at specular interfaces .................................................................................25 Scattering .....................................................................................................................................................26 REFRACTION ...................................................................................................................................................27 ATTENTUATION...............................................................................................................................................28 Definition and sources of attenuation........................................................................................................28 Values of Attenuation in Soft-tissue ..........................................................................................................28 How frequency affects attenuation ............................................................................................................28 Calculating Attenuation...............................................................................................................................28 USEFUL DIAGNOSTIC FREQUENCY RANGE ...............................................................................................29 TERMINOLOGY ASSOCIATED WITH IMAGE CHARACTERISTICS .............................................................29 Echogenicity.................................................................................................................................................29 Anechoic.......................................................................................................................................................29 Hyperechoic .................................................................................................................................................29 Homogeneity and heterogeneity ................................................................................................................30 Propagation of Ultrasound Through Soft-Tissue Quiz.................................................................................31

SECTION 3: ULTRASOUND TRANSDUCERS .................................................................. 35 PIEZOELECTRIC EFFECT ...............................................................................................................................37 Definition & Concepts .................................................................................................................................37 Piezoelectric Materials ................................................................................................................................37 Curie Point....................................................................................................................................................37 TRANSDUCER CONSTRUCTION & CHARACTERISTICS .............................................................................37 Operating (Resonance) Frequency ............................................................................................................37 Thickness resonance of crystal..................................................................................................................37 Frequency Characteristics ..........................................................................................................................38 Multi-Hertz ....................................................................................................................................................39 SOUND BEAM FORMATION ...........................................................................................................................43 Interference Phenomenon...........................................................................................................................43 Focal Distance..............................................................................................................................................43 Near Zone & Far Zone..................................................................................................................................43 Dependence on frequency & aperture .......................................................................................................44

3


Figure 2-3.

reflector at a 90-degree angle. It is perpendicular or normal incidence that yields the best images. The intensity of the reflected or transmitted sound is dependent on the impedance and incident angle. When the impedances are the same, all the intensity is transmitted.

Incident angle

Reflection angle

Figure 2-2.

Incident Pulse

Medium One

Medium Two

Reflected Pulse

Boundary Transmission angle

Transmitted Pulse

Oblique incidence – Non Perpendicular (reflection and transmission of sound)

Scattering Scattering is a result of ultrasound interacting or striking a reflector with rough edges or irregular shaped structures that are equal to the wavelength. When scattering occurs, the ultrasound is sent in all directions. Several things are considered to be scatterers such as: red blood cells, suspended particles, and gas bubbles. Scattering allows imaging of tissue boundaries that are not perpendicular to the direction of incident sound. Scattering helps to make imaging less angle-dependent. The echoes that are scattered back from an interface are called backscatter.

Perpendicular incidence (reflection and transmission of sound)

Anything that is not perpendicular is said to be oblique. Reflections occur only if there is a difference of acoustic impedances at the interface of two media. In normal incidence, reflection occurs only with two different impedances. The reflection and transmission coefficients (IRC and ITC) give the percentage of sound that is either reflected or transmitted. The two together must add up to 1 or 100 percent in order to account for all the intensity. Reflection may occur even if densities are the same, as long as the propagation speeds are different. When there is a large difference between the impedance of two media, as with air/skin, there is almost total reflection, or no transmission can occur. Ultrasound imaging would not be possible if a coupling gel with intermediate impedance was not used. With perpendicular incidence, the incident angle equals zero.

Figure 2-4.

Tissue 1

Tissue 2 Scattered sound

26


Homogeneous liver tissue Hypoechoic breast mass as compared to surrounding breast tissue

Isoechoic – has same or equal echogenicity.

Heterogeneous liver tissue from “fatty infiltrate�

Other terms used to characterize tissue based on echogenicity would include solid, cystic or complex/mixed. Solid referring to a primary composition from tissue while cystic refers to the primary components being from fluid. And the term mixed or complex refers to a combination as in the image below.

Renal parenchyma tissue is isoechoic or has same echogenicity as liver tissue

Homogeneity and heterogeneity Homogeneity and heterogeneity are used to denote tissue regularity or variability of the echo amplitude pattern. The echo texture of the normal liver is considered homogeneous or regular.

Complex breast mass with both cystic and solid components

30


ANATOMY OF HARMONIC DEVELOPMENT TIME vs. DISTANCE TRAVELED

harmonic signal. As described previously, the transmitted frequency is lower and the harmonic frequency is higher. In fact, it results in twice the fundamental frequency.

Near field = no harmonics

Video clip 3-a. Harmonics

Near mid-field = > harmonics Mid field = max harmonics Far mid-field = < harmonics Far field = no harmonics

Because of the weaker signal strength of tissue harmonics (100 times lower than fundamental signal intensity) a lower intensity signal generates minimal harmonics. This explains why harmonics can have a greater impact in cardiac imaging where the incident signal is around 420 mW/cm2 while abdominal imaging uses an intensity of < 100 mW/cm2 .

Courtesy of Philips Medical

At some point the penetration and production of harmonics will be ineffective due to attenuation. Figure 3-6.

Fundamental

The best portion of the field of view for tissue harmonic imaging will be limited and is dependent on the tissue medium and the fundamental signal intensity.

Harmonics

In summary, the advantages of harmonics are as follows:  Improved spatial resolution  Improved contrast resolution  Better signal to noise ratio

41


Figure 7-21.

ALIASING

The maximum Doppler shift a system can detect at a certain point in the display is called the Nyquist limit and is equal to onehalf the PRF. In other words, the Nyquist sampling rate is when PRFmax = 2fD. This limit defines the minimum sampling rate (PRF) for a signal whose frequency is fD. If the sampling rate is below the Nyquist limit (2fD), aliasing will occur. If it is above the Nyquist rate, the signal can be determined and displayed unambiguously. For example, if the PRF is 10 KHz, the maximum frequency shift the system can display in one direction is 5 KHz. If the received frequency shift exceeds 5 KHz, aliasing will occur.

Pulsed Doppler

Unlike CW techniques, pulsed Doppler transmits a signal and then waits to receive the reflected signal before sending a second signal. This is called the pulse repetition frequency or PRF and denotes the number of pulses per second the system is sending to the vessels. It is also called sampling or pulsing rate.

Figure 7-22.

The transmit pulse length is determined by the sample volume length. Long SV = long pulse length Small SV = short transmit pulse There are imaging and non-imaging Pulsed Doppler instruments. A transcranial transducer is an example of a non-imaging Pulsed Doppler Instrument. Duplex systems combine a real-time image with Doppler analysis.

Aliasing

Multi-element duplex transducer

117


7. The most anterior chamber of the heart is the: a. left ventricle b. left atrium c. right ventricle d. right atrium

ANATOMY AND PHYSIOLOGY QUIZ 1. The ASE recommends the left ventricle be divided into ____ segments: a. 3 b. 10 c. 17 d. 15

8. What structure in the right ventricle extends from the lower interventricular septum to the anterior wall where it joins the papillary muscle? a. chordae tendinae b. tricuspid valve c. moderator band d. trabeculations

2. In the parasternal long axis view, which of the following heart walls are visualized? a. mid inferior b. mid posterior c. anteroseptal d. basal e. b, c, and d f. a, c, and d

9. The right ventricular outflow tract is also referred to as the: a. conus arteriosus b. crista supraventricularis c. infundibulum d. b and d e. a and c

3. The area of the heart where the coronary sulcus meets the interventricular sulcus is called the: a. apex b. crux c. coronary sinus d. AV groove

10. What are the normal number of pulmonary veins? a. 6 b. 2 c. 3 d. 4 to 5

4. The inner surface of the heart wall is the: a. myocardium b. epicardium c. visceral layer d. endocardium

11. Where are the pectinate muscles located in left atrium? a. whole left atrium b. pulmonary veins c. posterior left atrial wall d. left atrial appendage

5. Which of the heart wall layers is responsible for the heartâ&#x20AC;&#x2122;s ability to contract? a. parietal pericardium b. myocardium c. epicardium d. endocardium

12. The cardiac structure that forms the right lateral cardiac border is the: a. left ventricle b. right ventricle c. right atrium d. left atrium

6. The left ventricular outflow tract ends at the level of the: a. aortic annulus b. left ventricle c. papillary muscles d. chordae tendinae

35


Elementary Principles Section Quiz

7. If the intensity of a signal is doubled, what is the affect on amplitude: a. halved b. quadrupled c. doubed d. squared

1. The audible range of sound is: a. <20 Hz b. > 20 Hz but < 20,000 Hz c. >20,000 Hz but < 1 MHz d. 1 MHz â&#x20AC;&#x201C; 20 MHz

8. The rate at which work is done is referred to as: a. pressure b. intensity c. power d. amplitude

2. Transducer frequency is directly proportional to: a. period b. wavelength c. sound intensity d. spatial pulse length

9. Which statement is most correct about power? a. Power is the rate of work b. Power is expressed as mW/cm2 c. Power and intensity are always the same d. Power is equal to the transfer of energy.

3. The term used to describe the number of cycles that occur in a one-second time period is: a. lambda b. frequency c. wavelength d. period

10. The percentage of time the sound is on is referred to as the: a. intensity b. amplitude c. period d. duty factor

4. Which is not considered an acoustic variable? a. pressure b. intensity c. particle motion d. density

11. A 6dB gain would indicate an increase in intensity of __________ times. a. 2 b. 4 c. 8 d. 10

5. What two characteristics of a medium determine itâ&#x20AC;&#x2122;s propagation speed? a. density & temperature b. temperature & pressure c. stiffness & pressure d. density & stiffness e. propagation speed is not affected by the medium.

12. The log of 10,000 is equal to: a. 2 b. 3 c. 4 d. 5

6. If the density of the medium increases, the speed of sound will: a. increase b. decrease c. not change

19


Gulfcoast Ultrasound Institute - workbook  

Originally introduced in 1993, and revised, rewritten and periodically updated, our popular P.A.S.S. (Preparation Agenda for Study Success)...

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