A patient is described in whom isometric movements of the right pectoralis muscle group totally suppressed pulse generator discharge of a ventricular inhibited pacemaker. Converting the pulse generator to the continuously discharging mode, by applying a magnet externally, prevented this inhibition. At surgery, the proximal electrode terminal was found to be improperly seated in the pulse generator and fluid had leaked into the connector boot. Two possibilities may explain the observed skeletal muscle-induced pulse generator inhibition: conversion of the bipolar demand system to a unipolar demand system by the fluid leak with subsequent sensing of myopotentials or the generation of false (make-break) electrical signals from repetitive interruption of the electrical circuit caused by pectoralis muscle activity.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine