How does cardiac defibrillation work?

How does cardiac defibrillation work?

Cardiac defibrillator is a device which delivers a high voltage direct current shock in a controlled fashion. It depolarizes the whole of the heart or at least a critical mass of the heart muscle so that all cardiac electrical activity stops for a moment. Usually the dominant pacemaker of the heart starts functioning after a short pause. If the electrical abnormality which caused the cardiac arrhythmia has ceased, the person continues in a normal heart rhythm. Otherwise the arrhythmia may recur.

How does cardiac defibrillation work