Cardioversion is a procedure used to restore a normal heart rhythm. It’s most often used to treat AFib, the most common type of heart arrhythmia. While some people have success with medications, most will require electrical cardioversion.

Cardioversion is a procedure used to treat heart arrhythmias like atrial fibrillation (AFib), which happens when the heart is beating too quickly, too slowly, or in an irregular manner.

The most common type of cardioversion is electric cardioversion, in which an electrical impulse is sent to the heart to shock it back into rhythm. But cardioversion can sometimes be achieved with medications.

Cardioversion is done in a hospital setting, but it’s usually an outpatient procedure. If you’re getting electric cardioversion, doctors will put you into a state of nonfeeling and unawareness called general anesthesia by using medications called anesthetics.

The procedure is very quick, but doctors will want to monitor you for a few hours afterward.

When an abnormal heart rhythm is causing significant distress or becoming a life threatening problem, cardioversion can go a long way toward restoring healthier heart function.

The two types of cardioversion are electrical and chemical (also referred to as pharmacological).

Electrical cardioversion, as the name implies, uses electrical impulses from electrodes placed on the chest to “shock” the heart back into a healthy rhythm. The procedure is brief because the heart usually responds immediately to the shock. How long the heart will remain in a healthy rhythm is difficult to predict.

Chemical cardioversion uses medications to restore a healthy heart rhythm. The medications are often given through an intravenous (IV) line, though they may be taken by mouth in some situations.

You may need cardioversion if your arrhythmia is causing significant symptoms or if it’s impacting your heart’s ability to function properly. Some arrhythmias are mild and require no treatment, other than preventive medications like anticoagulants, which help reduce the likelihood of stroke.

Cardioversion is most often administered to people with AFib, the most common type of arrhythmia. It occurs when the heart’s top chambers (atria) beat in a chaotic manner, out of sync with each other and the rest of the heart. Symptoms can be severe and include fatigue, chest pain, and weakness.

Other types of arrhythmia that could require cardioversion include:

Cardioversion is usually a safe and effective treatment, but it does carry some risks. Though it’s uncommon, cardioversion (both electrical and chemical) can cause a new and serious arrhythmia to develop.

Other potential risks include the development of less dangerous rhythms or more frequent episodes of the existing arrhythmia. Electrical cardioversion can, in rare cases, injure the heart, though the harm is usually minor and temporary.

In rarer cases, heart failure can result. If a blood clot is present in or near the heart, electrical or chemical cardioversion may dislodge it, raising the risk of a stroke.

Electrical and chemical cardioversion each have their own advantages and disadvantages. The right choice for you depends on several factors, including your age and overall health, as well as the type of arrhythmia you have.

Pros: Electrical cardioversion

  • generally more effective than chemical cardioversion
  • usually relieves symptoms
  • works almost instantly
  • can be repeated when the abnormal rhythm returns

Cons: Electrical cardioversion

  • requires general anesthesia, which can pose risks for some individuals
  • increases risk of blood clots and stroke
  • requires staying on anticoagulants and antiarrhythmic medications for most people
  • effects are usually temporary
  • possible delay in treatment until anticoagulant therapy is established
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Pros: Chemical cardioversion

  • doesn’t require sedation
  • can be followed by electrical cardioversion if it’s not effective
  • especially effective in treating atrial flutter

Cons: Chemical cardioversion

  • takes longer for the heart to go back into rhythm
  • less likely to successfully restore normal heart rhythm
  • effects are usually temporary
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Electrical cardioversion is sometimes tried only after chemical cardioversion fails to effectively restore a normal heart rhythm.

A 2020 study found that the combination of chemical cardioversion followed by electrical cardioversion led to slightly better outcomes than electrical cardioversion only.

The researchers also found that chemical cardioversion by itself led to positive outcomes in about half of those treated, suggesting that some people may not need electrical cardioversion after receiving the pharmacological therapy.

During an electrical cardioversion procedure, you’ll have soft electrodes placed on your chest. They’re attached to a cardioversion machine. You’ll receive anesthetics through an IV line to put you into anesthesia. While you’re under anesthesia, electrical impulses will travel through the electrodes, shocking your heart back into a normal rhythm.

The procedure takes just a few minutes, but you’ll be monitored for several hours for side effects and to assess your heart function.

During a chemical cardioversion procedure, you’ll receive antiarrhythmic medication through an IV line or by mouth. The procedure can be done in a hospital or doctor’s office or even at home using oral medications.

Cardioversion vs. defibrillation: What’s the difference?

Electrical cardioversion and defibrillation both use high-energy shocks to restore a healthy heart rhythm, but there are some important differences between the two procedures.

  • Cardioversion is used when the heart is beating in an abnormal rhythm.
  • Defibrillation should be used during a life threatening arrhythmia or if the heart has stopped beating altogether (cardiac arrest).
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To prepare, you’ll need to find out which medications you can take before the procedure.

You’ll also need to check with the healthcare team in the days leading up to your procedure to find out when you should stop eating and drinking before the cardioversion. Typically, before a morning procedure, you’ll be advised to stop eating by midnight.

Before chemical or electrical cardioversion, a doctor may perform a transesophageal echocardiography procedure, in which a thin, flexible catheter is guided down your throat to your chest to check for clots near your heart. If any are found, your procedure will likely be canceled or postponed.

Because you will receive anesthetics before electrical cardioversion, you’ll need to make arrangements for a ride home after it’s over.

How effective is cardioversion?

The effectiveness of cardioversion depends on several important factors, including the type of arrhythmia being treated and the overall health and age of the individual.

For example, findings of a 2018 study suggested that electrical cardioversion for people with AFib was associated with a low risk of cardiovascular events, such as a heart attack or stroke, for the first year. However, long-term success with cardioversion was less effective.

How do I stay in rhythm after cardioversion?

Antiarrhythmic drugs may be helpful for some people, but they carry an elevated risk of adverse events and mortality, according to a 2019 report.

You may benefit from a procedure called ablation, which destroys the small portion of heart tissue that may be causing your arrhythmia. Subsequent cardioversion procedures can help restore your heart rhythm for a period of time, but they don’t maintain it over the long term.

How many times can I have electrical cardioversion?

Technically, there’s no limit to the number of cardioversion procedures you can have. They don’t damage the heart and carry a low risk of negative side effects. However, if you have repeated cardioversion procedures and they restore a healthy rhythm for just a short amount of time, you should talk with a doctor about alternative treatments.

What are the side effects of cardioversion?

After electrical cardioversion, you may experience some redness at the sites of the electrodes and some minor chest pain. These are temporary side effects. Some medications used for chemical cardioversion can cause side effects such as nausea and headaches.

  • Cardioversion is a common treatment for heart arrhythmias like AFib.
  • Some people are able to use medications for cardioversion, but electrical cardioversion is more common.
  • Cardioversion has limited risks, but the results are rarely permanent.