Reduced incidence of myopotential pacemaker inhibition by abdominal generator implantation.

Myopotential inhibition during permanent pacing with unipolar leads is a well-recognized clinical problem. A study was undertaken to determine if implantation of the generator in abdominal subcutaneous tissue instead of the conventional pectoral implantation site would reduce the incidence of this inhibition. Forty patients with either an abdominal (group A, n = 20) or a pectoral (group P, n = 20) generator implantation site were subjected to a standardized protocol of muscle provocation and 24-hour ECG. Pulse generators were programmed to the lowest sensitivity level (average, 2.0 mV). Pauses exceeding the stimulation interval were analyzed. During muscle provocation 85% of the patients in group P displayed inhibition, as against 5% in group A (p less than 0.001). During 24-hour ECG, the corresponding values were 95% and 15%, respectively (p less than 0.001). We concluded that abdominal generator implantation significantly reduces the incidence of myopotential inhibition in patients with unipolar pacemaker leads.