Cardioversion (Electrical)

What is cardioversion?

Cardioversion is a procedure done to change an irregular or fast heart rhythm back to a normal rhythm. Electrical cardioversion does this by passing an electric shock through the chest to the heart. The single, rapid, high-voltage electric shock to the heart causes all the heart muscle cells to stop beating for a moment. This allows your heart to restart itself with a normal heart rhythm. The heart then beats normally again. To be successful, the shock must be delivered at just the right time during a heartbeat.

When is it used?

Abnormal heart rhythms (arrhythmias) such as atrial tachycardia and ventricular tachycardia may cause very rapid heart rates. The heart rate may be so fast that the blood does not flow through the body well. For some people with coronary artery or heart valve disease, an abnormally fast heartbeat can be life threatening. Cardioversion can quickly restore normal blood flow.

Some other rhythm problems, such as atrial flutter or atrial fibrillation, are not very fast but are abnormal and inefficient. If you are having problems because of an irregular heart rhythm, your healthcare provider might suggest treatment to return the heart rhythm to normal. Medicine is sometimes used, but when medicine doesn’t work, your provider might suggest electrical cardioversion.

How do I prepare for this procedure?

If the arrhythmia is life threatening, cardioversion is done without delay or special preparation.

For a planned cardioversion, follow the instructions your healthcare provider gives you. You may eat a light meal, such as soup or salad, the night before the procedure. Do not eat or drink anything after midnight and the morning before the procedure.

Plan for your care and recovery after the procedure.

What happens during the procedure?

You will be given a tranquilizer and a sedative (a light general anesthetic). These drugs will relax your muscles, put you to sleep, and keep you from feeling pain during the procedure. Your healthcare provider will put electrodes on your chest and back. Then an electric shock will be delivered through your chest for a fraction of a second. The electrical charge passes through 2 large, hand-held electrode paddles or 2 large adhesive patches placed on your chest. Abnormal heart rhythms usually return to normal with the first shock, but more shocks may be needed. Your healthcare provider will check your heart rhythm with an electrocardiogram (ECG, or EKG).

You will probably be unconscious from the anesthesia for less than 5 minutes. You will not remember the shock.

What happens after the procedure?

You will be monitored in the recovery room or coronary care unit for a short time. Your chest might be a little sore. You may have ring-shaped marks on your chest where the electrode paddles were placed. The marks will fade after several days.

When you are fully recovered from the anesthesia, you will probably be allowed to go home. Sometimes you may need to stay in the hospital overnight. Your healthcare provider may prescribe drugs to help your heart keep its new rhythm.

Ask your provider what you should do to take care of yourself and when you should come back for a checkup.

What are the benefits of this procedure?

• It is a very safe way to change an abnormal heart rhythm to normal. Cardioversion can save lives.
• Your heart usually goes back to a normal beat, reducing discomfort and abnormal work for your heart.
• The procedure has fewer complications than treatment with most drugs.

What are the risks associated with this procedure?

• There are risks from the light general anesthesia, but harmful reactions rarely occur. Discuss these risks with your healthcare provider.
• The procedure may not be successful and your heart rhythm may not change.
• You may have a small, burned area on your skin where the paddles were placed.
• A blood clot may become dislodged from the heart and cause a stroke.

Ask your healthcare provider how these risks apply to you.

When should I call my healthcare provider?

Call your provider right away if:

• Your heart rhythm becomes irregular or very rapid.
• You become short of breath.
• You have chest pain or pressure.
• You have pounding in your chest.
• You have dizziness.

Call during office hours if:

• You have questions about the procedure or its result.
• You want to make another appointment.