Cardioversion is a procedure used to restore the heart’s abnormal rhythm, or arrhythmia to a normal sinus rhythm. Physicians may use medication (chemical or pharmacological cardioversion) or electric shock (electric cardioversion) for this.

In electric cardioversion, a therapeutic dose of electric shock is delivered during a specific beat of the cardiac cycle.

Cardioversion is mostly used to treat arrhythmias of the upper chamber of the heart, like atrial fibrillation (AFib), and sometimes atrial flutter. More rarely, it may be used for arrhythmias of the lower chambers of the heart, also known as ventricular arrhythmias.