Cardioversion is a medical procedure that uses quick, low-energy shocks to restore a regular heart rhythm. It’s a treatment for certain types of irregular heartbeats (arrhythmias), including atrial fibrillation (A-fib). Sometimes cardioversion is done using medications.

Cardioversion is usually scheduled in advance but is sometimes done in emergencies. Usually, cardioversion quickly restores a typical heart rhythm.

Cardioversion is different from defibrillation, an emergency procedure that’s done when the heart stops or quivers uselessly. Defibrillation delivers more powerful shocks to the heart to correct its rhythm.