Treatment of Ventricular Fibrillation Using a Capacitor Discharge

Abstract

To test the efficacy of capacitor discharges in stopping ventricular fibrillation, a total of 227 tests were carried out on 52 dogs. In 192 tests the electrodes were applied directly to the ventricles, and in 35, electrodes were applied to the unopened chest. With the exposed hearts, capacitor discharges of 500 v. or more, equivalent to 5 watt-seconds, successfully defibrillated in a high percentage of cases, provided fibrillation had not gone on for more thant 40 seconds. In the closed chest experiments, the energy of the discharge needed to be of the order of 500 watt-seconds. If the fibrillation was allowed to continue for 1 minute or more before the capacitor shock was given, the chances of successful defibrillation decreased greatly in both open and closed chest experiments. To test the danger of producing ventricular fibrillation in a normal heart by capacitor discharges, an additional 119 tests were carried out on 6 dogs with the heart exposed. The results showed that low-energy capacitor discharges are much more likely to produce ventricular fibrillation than high-energy discharges. This is similar to the findings with alternating current shocks, where it is small currents rather than heavy currents which produce fibrillation.