Editing Defibrillation (section)

=== Waveform change ===
Until the mid 1990s, external defibrillators delivered a Lown type waveform (see [[Bernard Lown]]), a heavily damped [[sinusoidal]] impulse having a mainly uniphasic characteristic. Biphasic defibrillation alternates the direction of the pulses, completing one cycle in approximately 12 milliseconds. Biphasic defibrillation was originally developed and used for implantable cardioverter-defibrillators. When applied to external defibrillators, biphasic defibrillation significantly decreases the energy level necessary for successful defibrillation, decreasing the risk of burns and [[myocardial]] damage.

Ventricular fibrillation (VF) could be returned to [[sinus rhythm]] in 60% of cardiac arrest patients treated with a single shock from a monophasic defibrillator. Most biphasic defibrillators have a first shock success rate of greater than 90%.<ref name="jems" />