Comparison of electroporation thresholds of cardiac cell membranes by rectangular and exponential pulses

Electroporation may be a mechanism for injury to the cardiac cell membrane during electrical defibrillation, if excessive levels of shock are applied. A cell-attached patch-clamp study of single rat ventricular myocytes was conducted to determine whether the voltage thresholds for electroporation differ for two commonly used waveform shapes with widely different tilts: 5 ms rectangular (0% tilt) and 5 ms truncated exponential (67% tilt). When threshold was measured as leading edge voltage, the exponential pulses had, on average, a significantly higher threshold and shorter latency delay for electroporation compared with the rectangular pulses. Therefore, high-tilt exponential pulses may produce less injury via electroporation compared with rectangular pulses.