Complete AV block developing in a patient with manifest ventricular preexcitation.

This case report describes a 37-year-old man with manifest atriofascicular and fasciculoventricular connections who developed complete atrioventricular block. After resumption of 1:1 atrioventricular conduction, an electrophysiological study was conducted. During sinus rhythm, manifest ventricular preexcitation was observed and the AH and HV intervals were 80 msec and 50 msec, respectively. No change in AH interval during constant atrial pacing was observed by bolus injection of 20 mg of adenosine triphosphate. No changes in the morphology of the delta wave or HV interval were observed by changing the atrial pacing site. This patient developed HV block by atrial extrastimulus (S1S1: 600 msec, S1S2