Improved low energy defibrillation efficacy in man with the use of a biphasic truncated exponential waveform

Abstract The standard implantable defibrillator waveform is a truncated exponential of approximately 6 msec duration. This study compares the deflbrillation efficacy of a standard monophasic truncated exponential to a biphasic 12 msec truncated exponential waveform in 21 patients undergoing automatic implantable cardioverter defibrillator (AICD) surgery. For the biphasic waveform, the polarity was reversed and remaining capacitor voltage was attenuated by 75% after 6 msec. Two hundred thirty episodes of VF were induced with 115 “matched pairs” of monophasic and biphasic waveforms of identical initial capacltor voltages given over a range from 70 to 600 V (0.35 to 25.7 joules). The biphasic waveform was superior to the monophasic waveform ( p