“Escape-Reentry-Capture” Trigeminy: A Rare Electrocardiographic Sequence

Abstract

en a long pause follows sinoatrial block or atrioventnicular block, A-V junctional escape beat ensues. The same holds true for marked sinus bradycardia. Thus, it is natural that escape beats are encountered frequently in sick sinus syndrome. Ifsinus impulse resumes control ofthe ventricles, ie, “captures” the ventricles, and “escape-capture” occurs in succession, then “escape-capture” bigemmny is the result. Alternatively, mfthe next sinus beat is further detamed, junctional impulse can be conducted retrogradely to the atria and then back to the ventricles, eliciting a reciprocal beat. The underlying mechanism is reentry. Occurring in pairs and in succession, the phenomenon is “escape-reentry” bigeminy. Both “escape-capture” and “escape-reentry” bigemmny are common in sick sinus syndrome; however, the sequence of “escape-reentry-capture” trigeminy is a rarity. Recently, we encountered a case of bradycardiatachycardia syndrome displaying an ECG pattern of “escape-reentry-capture” during 24-hour telemetric ECG on the second day of hospitalization.