Atrial premature beat bigeminy with slow pathway conduction causing regular RR intervals.

A 74-year-old female patient presented with atrial premature beat (APB) bigeminy. Sinus beats were conducted via the fast pathway (FP), while APBs were conducted via the slow pathway (SP). Two types of QRS complexes with different natures appeared alternately, yet the RR intervals remained regular, mimicking accelerated junctional rhythm complicated with interfering atrioventricular dissociation. This article explores the pathogenesis of this rare electrocardiographic phenomenon.