Biphasic shocks induce more uniform repolarization than monophasic shocks in a cardiac cellular field excitation model

A model of an isolated cardiac cell in a uniform electric field was used to study the differences in action potential prolongation produced by monophasic and biphasic field stimulation. Repolarization times induced by shocks of varying strengths delivered at different times in the relative refractory period were measured. Monophasic shocks were found to produce greater average prolongation, but the standard deviation of the biphasic repolarization times was less. The more uniform response caused by the biphasic pulse may help to explain the greater efficacy of biphasic waveforms in defibrillation