Artificial cardiac pacemakers. 3

Unusual complications of epicardial pacemakers. Recurrent pericarditis, cardiac tamponade and pericardial constriction

Three patients with unusual complications after insertion of an epicardial pacemaker are described. In one patient pericarditis and severe cardiac tamponade developed that required emergency pericardiocentesis 8 weeks after pacemaker insertion. No evidence of myocardial perforation was observed at operation. In another patient two unusual complications developed: (1) migration of the pulse generator from the epigastric site of implantation into the pelvis, and (2) recurrent pericarditis with occult signs of constriction. In another patient recurrent pericarditis and clinical evidence of constriction developed. All three patients required pericardiectomy. Recurrent pericarditis after insertion of an epicardial pacemaker requires careful medical follow-up because either life-threatening tamponade or chronic constrictive pericarditis may develop.

Cardiac pacemaker induced ventricular fibrillation during surgical diathermy

Two demand pacemakers were observed to repeatedly fibrillate the heart during clinical surgery employing diathermy. Marked hypotension associated with a rapid, irregular venticular action was observed in another patient who had a fixed rate pacemaker implanted. Pacemakers were tested with function generators over a range of frequencies and some increased their rate to between 200-600 impulse/min. Animal experiments confirmed that, contrary to manufacturers advice, surgical diathermy produces myocardial fibrillation in the presence of some pacemakers. Mechanisms of these effects and their clinical significance are discussed.