Transmural conduction delay and block producing a pseudo-infarction electrocardiogram during treatment of anaphylaxis

Figures

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  Figure 1. Presenting electrocardiogram shows normal sinus rhythm. Intervals are R-R = 588 ms, PR = 172 ms, QRS = 92 ms, QT/QTc = 354/463 ms. A J wave is noted in the inferior and lateral leads.

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  Figure 2. On hospital day 4 telemetry monitor showed periods of QRS widening at sustained faster heart rates. A: In the 12-lead electrocardiogram (ECG) the rate is 111 beats/min with widespread “ST elevation” in a “tombstone” pattern as seen in acute myocardial infarction from epicardial coronary occlusion. The apparent ST elevation may actually represent a prolonged QRS complex due to transmural conduction delay (see text). B: Here the rate is approximately 89 beats/min and the QRS is narrow. This ECG was obtained within 9 minutes of the ECG in panel A. There are premature atrial beats (eg, complexes #5 and #13) showing little, if any, QRS widening. Selected R-R intervals are shown in milliseconds.

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  Figure 3. The electrocardiogram shows QRS complexes with a broad “tombstone” pattern, most of which are followed by apparent T-wave inversions. The sequence seen in beats 2-3-4, 8-9-10, and 10-11-12 show a “long-short” pattern of R-R intervals (intervals presented are in milliseconds). T-wave inversion is absent following the relatively premature QRS complex (asterisks). In a canine wedge preparation with acute coronary occlusion, T-wave inversion was demonstrated to represent delayed epicardial activation owing to transmural conduction delay caused by acute ischemia. If transmural conduction block occurred, the epicardium was not activated and T-wave inversion was absent. In the present case, rate-dependent block of INa produces transmural conduction delay leading to a wide QRS, while further rate-dependent block of INa (owing to a shorter, premature R-R interval) produces transmural conduction block that manifests as the absence of the T-wave inversion.