Key result
Vagal-induced sinus arrest suppresses ectopic QRS complexes, suggesting two-level Wenckebach periodicity in extrasystolic reentry.
Why the study?
The electrophysiological mechanism underlying intermittent ventricular bigeminy involving two-level Wenckebach periodicity in the reentrant pathway of extrasystoles was not previously described.
Case Report (n=1)
Supports mechanism distinction in ventricular bigeminy; leaves open prevalence and relevance of two-level Wenckebach periodicity.
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.
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Kinoshita et al. (1990) conducted a case report in Intermittent ventricular bigeminy (n=1). Vagal stimulation was evaluated on Occurrence of ectopic QRS complex. Vagal stimulation causing sinus arrest resulted in no ectopic QRS complexes, suggesting the presence of two-level Wenckebach periodicity in a reentrant pathway of extrasystoles.
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