A 67-year-old man with Wolff-Parkinson-White syndrome type A presented with second degree atrioventricular block in anomalous pathway and complete infra-Hisian block in the His-Purkinje pathway. He had increasingly frequent attacks of dizziness not related to exercise. A permanent ventricular demand pacemaker was successfully implanted following intracardiac electrophysiological studies.

Using His bundle recordings and ventricular stimulation retrograde conduction was studied in 57 cases of complete AV block. VA conduction was observed in 13 patients. Of the 13, 12 had AV block distal to H, and during cardiac pacing 5 of them showed a retrograde His bundle potential. In all cases the AV node-His pathway was implicated in the transmission of the retrograde impulse. There was no ...