Retrograde conduction in complete heart block.

Abstract
The right atrial ecg was recorded in 7 patients with complete heart block and 1 subject with 2:1 atrio-ventricular block during right ventricular pacing with biopolar electrode catheters. In 4 of the former patients and in the latter subject, retrograde P waves were detected. The cause of the dissociation between forward and retrograde block is unknown; further studies are required to elucidate this phenomenon.