Figure 1.

A: Electrocardiogram (ECG) of patient 1 obtained on presentation demonstrating normal sinus rhythm at a rate of 82 beats per minute (bpm) with normal intervals, normal axis, and no ST-T wave changes. B: ECG of patient 1 on day 1 of admission demonstrating complete heart block with an independent atrial rate at 80 bpm (blue arrow) and narrow complex escape ventricular rhythm at a rate of 50 bpm (red arrow). C: Patient 1 on day 3 of admission demonstrates escape-capture Wenckebach with a pattern of a conducted beat with a long PR (blue arrows) followed by a dropped beat and then apparent nonconduction of the subsequent P wave owing to occurrence of a junctional escape beat (red arrows). The significant variability of the R-R intervals and association of shorter R-R intervals with P waves demonstrates presence of some degree of AV conduction.