Supraventricular tachycardia triggering polymorphic ventricular tachycardia

Figure 1. Patient 1. A: Rhythm strip on admission showing supraventricular tachycardia of 250 beats per minute, triggering polymorphic ventricular tachycardia (VT). This run of polymorphic VT lasted 13.2 seconds and converted to sinus rhythm spontaneously. The coupling interval of the initiating beat was 310 ms. Following conversion to sinus rhythm multiple premature ventricular contractions (PVCs) were observed with 2 morphologies. The first PVC had a right inferior axis whereas the subsequent PVCs had left superior axis (similar to the PVC initiating polymorphic VT). B: Normal 12-lead electrocardiogram during sinus rhythm.

Figure 2. Patient 2. A: A 12-lead electrocardiogram showing very rapid regular tachycardia of 250 beats per minute (bpm) with typical right bundle branch block. B: Single-lead (lead II) rhythm strip showing regular supraventricular tachycardia at a rate of 250 bpm degenerating into polymorphic ventricular tachycardia (VT) of 12.5 seconds’ duration. The coupling interval of the first VT beat is 230 ms. This episode terminates spontaneously into sinus tachycardia. C: A 12-lead electrocardiogram post spontaneous reversion to sinus rhythm.

Figure 3. Patient 3. A: Rhythm strip at presentation, demonstrating regular supraventricular tachycardia of 260 beats per minute triggering a run of polymorphic ventricular tachycardia lasting for 8.5 seconds before spontaneous termination. The coupling interval of the initiating beat is 220 ms. B: Baseline 12-lead electrocardiogram during sinus rhythm.