Transthoracic defibrillation with chopping-modulated biphasic waveforms

The superiority of different biphasic pulses for transthoracic defibrillati on was proven by several studies. These efficient waveforms were implemente d in some commercially available defibrillators. Recently we have devised a nd evaluated a biphasic waveform with a specially balanced ratio of the fir st-to-second phase voltages and with 5 kHz frequency 1:1 on-off chopping. I t used less than half the energy for successful defibrillation in compariso n with the 'classic' monophasic damped sinusoidal wave and showed considera bly less postshock negative effects. This experience led us to try several laws of chopping modulation. A pulse-width modulation, combining low energy with gradual upslope of the modelled transmembrane potential, proved to ha ve better performance than the standard damped sinusoid wave and the non-ch opped biphasic truncated exponential pulse. This waveform was tested in a s eries of animal experiments in comparison with other modulated pulses, with the non-modulated waveform and the standard damped sinusoid wave. The expe riments demonstrated the superiority of the modulated waveform, assessed by combining the parameters of threshold defibrillation energy and of post-sh ock disturbances reduction.