Cardioversion is a procedure that uses external electric shocks to restore a normal heart rhythm.

Cardioversion is called defibrillation when it is done in an emergency to prevent death due to potentially fatal ventricular arrhythmias that can result in sudden cardiac arrest. Alternatively, your doctor can schedule cardioversion as a way to treat arrhythmias in the upper chambers of your heart called atrial fibrillation. If untreated, atrial fibrillation can increase your risk for stroke and heart failure.

Scheduled cardioversion procedures may be done in a hospital or other health care facility by cardiologists, or doctors who specialize in the heart. While the procedure takes only a few minutes, it requires that you arrive a few hours before the procedure. To prepare, you will be given anesthesia through an intravenous (IV) line in your arm to make you fall asleep, and you will have electrodes placed on your chest and possibly your back. These electrodes will be attached to the cardioversion machine. The machine will record your heart’s electrical activity and send the shocks to your heart. When ready, the doctor will send one or more brief, low-energy shocks to your heart to restore a normal rhythm. You will not feel any pain from the shocks.

You will need to stay for a few hours after your procedure. During this time, your health care team will monitor your heart rhythm and blood pressure closely and watch for complications. You will need a ride home because of the medicines or anesthesia you received. You may have some redness or soreness where the electrodes were placed. You also may have slight bruising where the IV line was inserted in your arm.

Although uncommon, cardioversion has some risks. It can cause or worsen life-threatening arrhythmias that will need to be treated. This procedure can cause blood clots to break away and travel from the heart to other tissues or organs and cause a stroke or other problems. Taking anticlotting medicines before and after cardioversion can reduce this risk.

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