Atrial-Pacemaker Block, A New Electrocardiographic Syndrome Associated with Implanted Synchronous Pacemakers

Abstract

A new electrocardiographic syndrome of second degree atrial pacemaker block has appeared following the implantation of a synchronous pacemaker. Unusual electrocardiographic features of electrial pacing and ventricular fusion beats were noted. This is the result of a delay of the atrial impulses reaching the atrial pickup electrode as the impulse may normally traverse the A-V junction. Supernormal ventricular excitation was demonstrated when a sinus beat fell at a critical period (0.48 seconds) following ventricular discharge. Transitory atrial pickup block has no linical significance in this type of synchronous pacemaker, since the fixed rate pacemaker automatically takes over the impulse formation.