Low-energy biphasic waveform defibrillation reduces the severity of postresuscitation myocardial dysfunction

Both clinical and experimental studies have demonstrated substantial impair ment of ventricular function after resuscitation from cardiac arrest. Indee d, postresuscitation myocardial dysfunction has been implicated as a potent ially important mechanism, accounting for fatal outcomes after successful r esuscitation in 70% of victims within the first 72 hrs, Recent experimental studies implicated the total electrical energy delivered during defibrilla tion as an important correlate with the severity of postresuscitation myoca rdial dysfunction and postresuscitation survival. This prompted us to inves tigate the option of using lower electrical energy biphasic waveform defibr illation. We compared the effects of low-energy biphasic waveform defibrill ation with conventional monophasic waveform defibrillation after a short (4 mins), intermediate (7 mins), or prolonged (10 mins) interval of untreated ventricular fibrillation, Biphasic waveform defibrillation with a fixed en ergy of 150 joules proved to be as effective as conventional monophasic dam ped sine waveform defibrillation for restoration of spontaneous circulation , with significantly lower delivered energy. This was associated with signi ficantly less severity of postresuscitation myocardial dysfunction, The low -energy biphasic waveform defibrillation is, therefore, likely to be the fu ture direction of transthoracic defibrillation in settings of cardiopulmona ry resuscitation.