Prolongation of atrioventricular conduction time by electrical stimulation of the carotid sinus nerves in man.

Electrical stimulation of the carotid sinus nerves was applied during diagnostic catheterization of two patients who had coronary artery disease. The immediate reflex prolongation of the atrioventricular (AV) interval was due to prolongation of the AH interval only and was roughly parallel to the reflex RR interval prolongation evoked without atrial pacing. After cholinergic block, the reduced prolongation of both the RR interval and the AV interval caused by reflex inhibition of sympathetic tone followed a time course similar to the arterial pressure decrease. This is the first demonstration in man of the parallel baroreflex effects on the sinoatrial node and the AV node.