The Effect Of Temporal Separation Of Phases On Biphasic Waveform Defibrillation Efficacy

Abstract

Biphasic waveforms have been shown to be more effective than monophasic waveforms of the same or one half the same duration[l]-[14]. It has been hypothesized that the improved defibrillation efficacy of biphasic waveforms is due to the rapid and large voltage change at phase reversal[l5]. Previous studies with sequential monophasic pulses given through two separate lead systems in pigs found the optimal separation of pulses to be 0.2 ms[16]. The effects of separating the two phases of a biphasic waveform in time on defi brillation energy requirements are unknown. We have examined these effects on two different biphasic waveforms using several interphase time delays. Thus by separating the two phases and splitting the voltage change at phase reversal in half, we were able to examine the contributions of this rapid voltage change on defibrillation requirements. We found that interphase time delays up to 6 ms did not affect the defibrillation efficacy of the two biphasic waveforms tested. Thus with the time delay, the rapid voltage change at phase reversal is split in half and cannot explain the improved efficacy of the biphasic waveforms. Methods