ECGs FOR THE EMERGENCY PHYSICIAN
This figure also corresponds to case #101. These are additional ECGs to reinforce the point Determination of ST-segment morphology Non-AMI
AMI
BER
AMI
ST-segment elevation in AMI – the initial, upsloping portion of the ST-segment–T-wave complex is concave (“sagging downward”) most often in non-AMI causes of ST-segment elevation, such as benign early repolarization. This morphology is compared to the flattened or convex pattern (“bulging upward”) observed in the AMI patient. This morphologic observation is a very useful tool in “ruling in” AMI in chest pain patients with ST-segment elevation. Similar to many tools in clinical medicine, this electrocardiogrphic tool should only be used as a guideline. As with most guidelines, it is not infallible; patients with ST-segment elevation due to AMI may demonstrate transient concavity of this portion of the waveform, as seen in this case example. The elevated ST-segment morphology may be determined by drawing a line from the J point to the apex of the T-wave: concave morphologies are noted when the ST-segment falls below the line while concave morphologies are demonstrated when the ST-segment is above the line
Right ventricular MI can be confirmed by performing an ECG using right-sided chest leads (see cases #30–31) or with bedside echocardiography. The presence of right ventricular extension of inferior MI is associated with increased morbidity and mortality. Preload-reducing medications (for example nitrates) should be used with caution, if at all, in patients with right ventricular MI. Low voltage in this case was caused by the patient’s obesity and was evident on prior ECGs as well. 102.
SR, rate 69, LVH, intermittent WPW. The amplitudes and morphologies of the QRS complexes change within each lead. These changes are clues that some type of abnormal ventricular conduction is occurring on an intermittent basis. Close inspection reveals that the second, fifth, eighth, and ninth QRS complexes are associated with the classic triad of WPW: short PR-segments, slightly wider QRS complexes, and delta-waves.
103.
SR, rate 82, prolonged QT. The QT-interval appears prolonged because of a large, “camel-hump” type of T-wave. This type of T-wave should prompt consideration of two possibilities:
130