Analysis of re entry mechanisms in three patients with concealed Wolff Parkinson White syndrome

Abstract

Three patients with recurring attacks of supraventricular tachycardia and no electrocardiographic evidence of the Wolff Parkinson White syndrome (WPW syndrome) were studied using intracardiac recordings and atrial stimulation. The findings are interpreted as evidence of a concealed WPW syndrome. In all patients there was anterograde block of the anomalous atrioventricular (AV) pathway while retrograde conduction was unimpaired and allowed the initiation of the observed reciprocating tachycardias. The diagnosis was based on the assumption that the ventricular myocardium was an essential link in the reentry circuit. The 3 most important findings to support this assumption are: retrograde conduction time, measured by the QA' interval (Q in ECG to atrial echo), and the rate of tachycardia were dependent on the mode of intraventricular conduction; the first QA' interval of the tachycardia was independent of the AH interval (initiation of atrial impulse to first activation of the His bundle) of the initiating premature atrial depolarization (PAD); there was retrograde conduction following a ventricular premature beat during tachycardia at a time when the AV node and/or the bundle of His would be refractory.