Cardioversion can correct a heartbeat that's too fast (tachycardia) or irregular (fibrillation). Cardioversion is usually used to treat people who have atrial fibrillation or atrial flutter. These are conditions in which the electrical signals that cause your heart to beat in a regular rate and rhythm don't properly travel through the upper chambers of your heart.
Cardioversion is performed when your heart is beating ineffectively. It's different from defibrillation, an emergency procedure that's performed when your heart stops or quivers uselessly. Defibrillation delivers more powerful shocks to the heart to correct its rhythm. Cardioversion is usually scheduled in advance but is sometimes done in emergency situations.
Cardioversion is usually done with electric shocks, administered through electrodes attached to your chest, while you're sedated. Electric cardioversion takes less time than cardioversion done solely with medications, and your doctor can instantly see if the procedure has restored a normal heartbeat.
If your doctor recommends cardioversion with medications to restore your heart's rhythm, you won't receive electric shocks to your heart.