Aim of study: The waveform designs and their relative defibrillation efficacy of external biphasic waveforms may differ remarkably among manufacturers. In this study, we compared pulsed biphasic waveform (PBW) with rectilinear biphasic waveform (RBW) and their effects on terminating ventricular fibrillation (VF).
Methods: VF was electrically induced and untreated for 10s in 6 domestic pigs weighing between 56 and 70 kg. The animals were then randomized to attempt defibrillation with either a PBW or RBW shock at energy levels of 50-200 J. If the delivered shock failed to terminate VF, a 150 J rescue shock was delivered with the same waveform. After a recovery interval of 4 min, the sequences were repeated for a total of 60 test shocks. The 50% and 80% defibrillation thresholds (DFT) were then calculated for the compared waveforms.
Results: No differences were observed in energy DFT50 and DFT80. Although the peak current and average current of the PBW were higher than RBW, there was no change observed in ST segment following shocks with both waveforms.
Conclusion: In the setting of this experiment, there was no difference in terms of defibrillation efficacy and myocardial injury related to the electrical shocks of the two waveforms.