Update on external cardioversion and defibrillation.

External cardioversion is a technique used electively or emergently to terminate arrhythmias such as atrial fibrillation, ventricular tachycardia, and ventricular fibrillation. There have been several advances made to modern defibrillators, including an improvement in the efficacy of the delivered shock. Biphasic shock waveforms have been shown to be superior to monophasic shocks and these are being incorporated into modern units. This paper reviews several reports on biphasic defibrillation. In addition, initiatives to make defibrillators more accessible are also being tested. Although not a technological advance, this initiative may significantly improve the survival of victims of out of hospital cardiac arrests.