Intermittent Ventricular Bigeminy as an Expression of Two-Level Wenckebach Periodicity in the Reentrant Pathway of Extrasystoles

A patient with intermittent ventricular bigeminy is reported in whom the presence of two-level Wenckebach periodicity in the reentrant pathway of extra-systoles is suggested. When sinus arrest was caused by vagal stimulation, no ectopic QRS complex occurred. This indicated that ventricular bigeminy was not parasystolic bigeminy but ordinary extrasystolic bigeminy. Observations of the electrocardiogram suggested that Wenckebach block occurred at two different levels in the reentrant pathway of ventricular extrasystoles. When extrasystoles were noninterpolated, Wenckebach block occurred at the distal level of the pathway and caused termination of ventricular bigeminy. On the other hand, when extrasystoles were interpolated, Wenckebach block occurred at the proximal level of the pathway. This is the first report to suggest the presence of two-level Wenckebach periodicity in a reentrant pathway of extrasystoles.