Cardioversion is the process by which an abnormal heart rhythm (arrhythmia) is restored to normal. Arrhythmia can result in improper blood supply to the heart and brain, adversely affecting their functions. Cardioversion may be delivered by medication (pharmacologic cardioversion) or electric shock to the heart (electrical cardioversion).

Electrical cardioversion is performed under sedation. Your doctor places two paddles on your body (both on your chest, or one on your chest and the other on your back) through which electrical shocks, each lasting less than a second, are delivered. Usually one shock is enough to restore the heart rhythm. The heart rate and rhythm are then examined. The whole procedure lasts for less than 30 minutes.