Defibrillation is a technique used in emergency medicine to save lives when the heart is in an abnormal or damaging rhythm.
Defibrillation involves applying a controlled electrical shock to the heart, simultaneously depolarizing its electrical conduction system, which can permit the heart's electrical rhythm to return to normal. Although the process can be repeated, the number of attempts is, in practice, limited, to a series of three or four attempts at increasing voltages, as the likelihood of restoring normal heart rhythm is much less in successive attempts.
An automatic external defibrillator (AED) is now available for use by laypeople.
Defibrillation can cause electrical burns.