Suppression of an external demand pacemaker by diaphragmatic myopotentials: a sign of electrode perforation?

Transient pacemaker inhibition was observed in a patient with an external bipolar demand pulse generator. Recordings of the proximal, distal and bipolar electrograms showed extracardiac myopotentials only in the unipolar distal and bipolar configuration. These myopotentials which caused inhibition of the pulse generator were related to respiration and other maneuvers that resulted in active contraction of the diaphragm, thus proving their diaphragmatic origin.