PROTECTION OF IMPLANTED PACEMAKERS FROM EXCESSIVE ELECTRICAL ENERGY OF DC SHOCK

Studies were performed on implanted pacemakers subjected to electroshock in 55 dogs. With exposure to 400 w.sec., electrical energies of 18 ma. and 29 v. were recorded in the epicardial lead system and energies of 1,000 ma. and 350 v. recorded in the epicardial ground plate lead systems. One of 20 Medtronic pacemakers having the bipolar lead system configuration was damaged in the experiment. Three of five Cordis Corporation pacemakers without protective zener diode circuitry were damaged. The addition of shunt diodes in the Cordis pacemaker input/output terminals provided a significant measure of protection. Implanted pacemakers may be made less vulnerable to electrical shock by incorporating components with adequate transient breakdown ratings and by employing electrodes of small surface area, small interelectrode distance and electrode orientation perpendicular to the defibrillator paddles. © 1969.