Electrical cardioversion

Electrical cardioversion involves applying an electrical current through the heart in order to restore a normal sinus rhythm.

Electrical cardioversion

Electrical cardioversion is a medical procedure that restores a normal heart rhythm in people with certain types of abnormal heart beats (arrhythmias). Cardioversion is usually done by sending electric shocks to your heart through electrodes placed on your chest. It’s also possible to carry out cardioversion using medication.

Cardioversion is usually a scheduled procedure performed in a hospital. You should be able to go home the same day as your procedure.

For most people, cardioversion quickly restores a normal heart rhythm.

Why cardioversion is carried out

Cardioversion can correct a heart rate that is too fast (tachycardia) or irregular (fibrillation). Cardioversion is usually used to treat people who have atrial fibrillation or atrial flutter. These conditions occur when the electrical signals that normally make your heart beat at a regular rate don’t travel properly through the upper chambers of your heart. Cardioversion is carried out when your heart is beating ineffectively.

This procedure is usually scheduled in advance but sometimes it’s also done in emergency situations. Cardioversion is usually done with electric shocks, administered through electrodes attached to your chest while you’re sedated. Electrical cardioversion takes less time than cardioversion performed solely with medication, and your doctor can see instantly whether the procedure has restored a normal heart rhythm. If your doctor recommends cardioversion using medication to restore your heart rhythm, you won’t receive electric shocks to your heart. Cardioversion is 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.

Risks associated with electrical cardioversion

Complications of electrical cardioversion are rare and doctors can take steps to reduce your risk. The main risks of cardioversion include:

  • Dislodged blood clots.

Some people who have irregular heartbeats have blood clots in their heart. Electrical cardioversion can cause these blood clots to move to other parts of your body. This can cause potentially life-threatening complications, such as a stroke. In order to prevent this complication, an anticoagulant treatment is prescribed before the procedure and an echocardiography check can be done to ensure there is no clot.

  • Abnormal heart rate.

In rare cases, some people who undergo cardioversion end up with other heart rhythm problems during or after their procedure. This is a rare complication. If this happens, it usually appears only minutes after your procedure, so your doctor can give you medications or additional shocks to correct the problem.

  • Skin burns.

In rare cases, some people get minor burns on their skin where the electrodes were placed. Pregnant women can have cardioversion, but it is recommended that the baby’s heart rate is monitored throughout the procedure.

How to prepare

Cardioversion procedures are usually scheduled in advance, but if your symptoms are severe, you may need to undergo cardioversion on an emergency basis. As a general rule, you can’t eat or drink anything for about 8 hours before your procedure.

Your doctor will tell you whether you should take any of your regular medications before the procedure. If you do take any medications before your procedure, sip only enough water to swallow your pills. Before cardioversion, you may have a procedure called a transoesophageal echocardiogram (TOE) to check for blood clots in your heart, which can be dislodged by cardioversion, causing potentially life-threatening complications. Your cardiologist will decide whether you need a transoesophageal echocardiogram before the cardioversion. During a transoesophageal echocardiogram, your throat is numbed and a probe is guided down your throat and into your oesophagus, the tube which connects your mouth to your stomach. From there, the probe can obtain more-detailed images of your heart so that your doctor can check for blood clots. If your doctor finds blood clots, your cardioversion will be delayed for three to four weeks while you take anticoagulant medications to reduce your risk of complications.

What to expect from the procedure

  • During the procedure

A nurse or technician will place several large patches called electrodes on your chest. The electrodes will be connected to a cardioversion machine (defibrillator) using wires. The defibrillator will record your heart rhythm throughout the procedure and will deliver shocks to your heart to restore the normal heart rhythm. This machine can also correct your heart rate if it beats too slowly after cardioversion. Before the shocks are delivered, a nurse or technician will insert an intravenous line in your arm. This infusion is used to give you medications that will make you sleep during the procedure so that you won’t feel any pain from the shocks. Your doctor may also use the intravenous line to give you additional medications that can help restore your heart rhythm. Once you are sedated, electrical cardioversion only takes a few minutes.

  • After the procedure

Electrical cardioversion is carried out on an outpatient basis, meaning you can go home on the same day you have your procedure. You’ll spend around an hour in a recovery room being closely monitored for complications. Because you’ll be asleep during the procedure, your awareness of your surroundings may be affected afterwards. You’ll need someone to accompany you home, and your ability to make decisions may be affected for several hours after your procedure.

Even if no clots were found in your heart before the procedure, you should take anticoagulants for at least several weeks after the procedure to prevent new clots from forming.


For most people, cardioversion can quickly restore a regular heart rhythm. It’s possible you’ll need to repeat these procedures to maintain a normal heart rhythm. To keep your heart healthy, you may need to make some changes to your lifestyle to improve the overall health of your heart, especially to prevent or treat conditions that can cause arrhythmias, such as high blood pressure.