Cardioversion is a procedure that can correct an irregular heart rhythm. An irregular heartbeat is also known as an arrhythmia. An arrhythmia occurs when the electrical impulses that direct your heart to beat aren’t firing properly. This causes the heart to beat too fast (tachycardia), too slow (bradycardia), prematurely, or with an irregular rhythm.
A healthcare professional called an anesthesiologist will give you medication to sedate you during the procedure. During a cardioversion procedure, a defibrillator machine sends an electrical shock to the heart muscle to restore the normal rhythm.
Cardioversion is not the same as defibrillation, the type of life-saving treatment you see in many television or movie depictions of hospital emergency rooms. Both cardioversion and defibrillation use energy to shock the heart, but defibrillation gives high-energy shocks to restore severely irregular arrhythmias or stopped hearts.
Medications can also correct arrhythmias. This type of treatment is called pharmacological cardioversion, but this article addresses the electrical procedure only.
A cardiologist will perform the cardioversion procedure in a hospital lab.
Your doctor may recommend cardioversion if you have an arrhythmia. If left untreated, an arrhythmia may become life threatening and lead to serious problems, such as a heart attack or stroke. Cardioversion can restore a natural rhythm so your heart will beat as it should.
In addition to an irregular heartbeat, which may not be easy to detect without medical tests, people with an arrhythmia may experience:
- extreme fatigue (tiredness)
- chest discomfort
- shortness of breath
- pounding or fluttering in the chest
Atrial fibrillation (A-fib) and atrial flutter (an abnormality of heart rhythm) are the most common types of arrhythmia treated with cardioversion. In some cases, cardioversion is used as a life-saving measure. Specifically, cardioversion can correct ventricular tachycardia, a rapid, life-threatening rhythm. However, in most cases, cardioversion is a planned procedure.
Check with your doctor to see if you’re allowed to eat or drink prior to the procedure. In most cases, you will need to fast beginning at midnight the morning of your procedure.
Also check with your doctor before taking any of your regular medications on the day of your procedure. Having food and liquid in your stomach during the procedure can increase your risk of complications, and your doctor may have to reschedule the procedure if you were unable to fast.
When in doubt, call your doctor’s office or hospital staff to find out how you should proceed.
Before the procedure begins, you will be asked to undress and wear a hospital gown. You will lie on a bed, and a nurse will begin an intravenous (IV) line in your arm or hand. The IV will deliver medication and fluids to you before, during, and after the procedure. One of these medications will be a sedative to make you sleep during the procedure.
A nurse will place adhesive patches or pads called electrodes on your chest. In some cases, the nurse will also need to place electrodes on your side or back. (Men may need to have their chest hair shaved prior to this procedure.) These electrodes are attached to the defibrillator machine, which both measures your heart’s electrical activity and sends energy to the pads to help “shock” your heart into a regular rhythm.
Doctors will send low-level amounts of energy from the defibrillator through the electrodes on your chest to your heart. These “shocks” interrupt the irregular electrical rhythm of the heart and restore a more normal heart rate. Your healthcare team will be able to check both your heart rhythm and blood pressure throughout the procedure.
According to the National Institutes of Health (NIH), cardioversion restores a normal heart rhythm in 75 percent of the people who have the procedure. However, an arrhythmia may develop again. In that case, you will need to have additional cardioversion procedures.
Cardioversion may not correct your arrhythmia. In some cases, it can actually cause more serious, life-threatening arrhythmias. After the procedure, your healthcare team will closely monitor your heart rate. They will watch for any signs of potentially dangerous changes. If they discover an irregularity, your doctor should be able to treat it immediately. Most often, they’ll use another electrical charge or medicine.
If a cardioversion procedure is not performed correctly, the electrodes may shock you during the transfer of energy. This can cause additional rhythm problems, pain, and—very rarely—death.
If a blood clot dislodged during the procedure travels to other organs or tissue, you could suffer a stroke, pulmonary embolism, or other severe complication. To prevent this risk, many doctors prescribe an anticlotting medicine for you to take before and after the procedure.
The cardioversion electrodes may cause some redness or minor burns on your skin. These should disappear within a few days of the procedure. The IV may also cause bruising or soreness at the insertion site.
The procedure is very quick — it only takes a few minutes. But you will need to remain at the hospital for several hours after the procedure to recover. Doctors and nurses will monitor your heart rhythm to see if the cardioversion was successful.
The sedation medicine you received before the procedure will make you drowsy for several hours. Arrange for someone to pick you up from the hospital and take you home.
Schedule a follow-up visit with your doctor a few days after the procedure to check your heart rate and find out if the procedure was successful.