Mechanisms of electrical defibrillation: Impact of new experimental defibrillator waveforms

Academic Article


  • Six pessible explanations for why some biphasic waveforms have lower defibrillation thresholds than monophasic waveforms of the same duration are as follows: (1) the impedance for the second phase of the biphasic shock is very low because electrode polarization develops during the first phase; (2) the large change in voltage between the first and second phases of a biphasic waveform is responsible for the increased defibrillation efficacy; (3) biphasic waveforms cause less severe detrimental effects in regions of high potential gradient; (4) the first phase of the biphasic waveform restores activity of the sodium channels, which makes defibrillation easier for the second phase; (5) the potential gradient required for defibrillation is less for biphasic waveforms than for monophasic waveforms; and (6) biphasic waveforms are better able to stimulate the myocardium to induce new action potentials or to cause refractory period prolongation. Evidence shows that, while a few of these proposed mechanisms are incorrect, several of the others may together contribute to the general superiority of biphasic waveforms. © 1994.
  • Authors

    Published In

    Digital Object Identifier (doi)

    Author List

  • Blanchard SM; Ideker RE
  • Start Page

  • 970
  • End Page

  • 977
  • Volume

  • 127
  • Issue

  • 4 PART 2