[Inhibition and triggering of heart pacemakers by muscle potentials]

The unipolar pulse generator systems were tested in 220 patients (96 VVIM, 97 VVIO, 27 physiological systems) to determine the incidence of sensing interference with muscle potentials. 23% exhibited oversensing, with a sex distribution of 32% for males and 15% for females. The interference was observed more often in VVIM pacemakers at nominal setting (35%) than in VVIO pacemakers (11%). In DDD pacemakers both inhibition and triggering of ventricular stimulation was observed. Among the 23 patients with persisting syncope or dizziness after implantation of the pacemaker, the symptoms were observed during physical activity only in 5. In these 5 the underlying arrhythmia was tachycardia in 3 and inhibition of the pacemaker by muscle potentials in only one patient.