Cardiac Arrhythmias Following Condenser Discharges Led Through an Inductance:

In order to evaluate the significance of an inductance in the condenser discharge circuit of defibrillators, additional experiments were performed by methods similar to those reported previously. 1 An inductance of 0.29 henry was connected in series with the condenser. It was shown that this modification results in a much higher threshold for arrhythmias than the threshold found earlier with pure condenser discharges. The differences were highly significant and show that functional damage to the heart, evaluated by the number and severity of arrhythmias produced, is less with an inductive resistance than without it. Inductive damping reduced the incidence of fibrillation by two-thirds. In 2160 damped discharges, ventricular fibrillation occurred only 36 times, all in the relative refractory period of the cardiac cycle. Fibrillation did not appear when the discharge was applied in the absolute refractory period or in the excitable period.