Abstract P23: Comparison of Effects of Pulsed Biphasic Waveform and Rectilinear Biphasic Waveform for Ventricular Fibrillation
Introduction Biphasic waveforms are superior to monophasic waveforms for electrical defibrillation. However, biphasic waveforms may themselves differ in efficacy. We hypothesized that the Pulsed Biphasic Waveform (PBW) had potential advantage of higher peak current and lower energy. Since higher energy shocks produce greater postresuscitation myocardial injury, higher peak current may be equally effective for defibrillation at lower delivered energy. We therefore compared the newly developed PBW with the more conventional rectilinear biphasic waveform (RBW) and their effects on terminating ventricular fibrillation (VF).
Methods In 6 domestic pigs weighing between 56 –70 (62±5) kg, VF was electrically induced and untreated for 10 seconds. Animals were randomized to attempted defibrillation with either a PBW or RBW shock at energy levels of 50 to 200 Joules. If the delivered shock failed to terminate VF, a 150 Joule rescue shock was delivered with the same waveform. After a recovery interval of 4 minutes, the sequences were repeated for a total of 30 test shocks. The 80% defibrillation threshold (DFT80) was then calculated together with measurements of ST segment differences to quantitative severity of myocardial injury.
Results No differences between the two groups were observed in energy DFT80 (Figure 1⇓). Although the peak current of the PBW was greater, both waveforms produced equivalent success and comparable severity of myocardial injury.
Conclusion If the energy levels are kept constant, the difference in peak current did not in this setting affect the efficacy and safety of the two waveforms.