Transthoracic ventricular defibrillation with very high amplitude rectangular pulses

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Abstract
Ventricular fibrillation was induced in anesthetized dogs. After 30 sec. of fibrillation, the unidirectional, rectangular shock being investigated was supplied to the chest. Trials in which defibrillation was achieved on the initial attempt were recorded as successful. Data were obtained for plotting a family of curves of percent success versus duration of shock for currents of 20, 40, 80, and 100 amp and at durations from 40 [mu]sec. through 1.5 msec. Curves of percent success versus energy were derived from the percent success versus duration curves. The data indicate that at the 100-amp level some successful defibrillations are observed with shocks as short as 40 [mu]sec., shocks with very fast rise times (in the order of 3 [mu]sec.) can be quite effective, and that for any given energy content the effectiveness decreases as the current is increased over the 20-to 100-amp range. Defibrillation can be achieved at minimum energy levels with shocks in or near the 10-to 20-amp range.