Understanding Electrical Cardioversion

Cardioversion is a procedure that is done to return your heartbeat to a normal rhythm. It’s done when the heart is beating very fast or irregular (arrhythmia). During the procedure, an energy shock is sent to the heart to reset it to a normal rhythm. This is done with a small machine that sends electric shocks to electrode pads on your chest. Cardioversion is not the same as defibrillation. Both use shocks to reset the heart. But defibrillation is used to treat ventricular fibrillation, a heart rhythm that can cause cardiac arrest

Cardioversion is most often a scheduled procedure. But in some cases, it may be done as an emergency treatment. This is done if symptoms are severe. You will be given medicine to make you sleep through the procedure.

Why electrical cardioversion is done

An arrhythmia can cause problems such as fainting, stroke, heart attack, and even sudden cardiac death. Electrical cardioversion can help treat several kinds of arrhythmias.

It is most often used to treat atrial fibrillation (AFib). With this condition, the top chambers of the heart (atria) quiver instead of beating normally. When this happens, blood can sit in these chambers without moving. It can form clots that can travel to the brain and other parts of the body. 

Symptoms of AFib may include shortness of breath, fatigue, chest pain, and a very fast heartbeat. It can also increase risk for stroke.

But your healthcare provider may not want you to have cardioversion if you:

  • Have minor symptoms from Afib

  • Are an older adult who has limited activity

  • Have had AFib a long time

  • Have other major health problems and can’t take medicines such as blood thinners

Other treatments may be better for you, such as heart rate control with medicine. A procedure called an ablation may also be considered if electrical cardioversion is not successful.

Electrical cardioversion is also used for treating other arrhythmias such as:

  • Atrial flutter

  • Supraventricular tachycardia

  • Some kinds of atrial tachycardia

  • Some kinds of ventricular tachycardia

These arrhythmias can cause heart rates that are too fast. This can prevent the heart from pumping enough blood.

How electrical cardioversion is done

The procedure takes only a few minutes. The healthcare provider will stick soft electrode pads on your chest and back. The provider may shave these areas of skin first. This is to help the electrode pads stick. The provider will attach wires to the electrodes. The wires connect to a cardioversion machine. You will get medicine to make you fall asleep. The machine sends a programmed energy shock to your heart. This should convert your heart back to a normal rhythm. You should not feel any pain.

Risks of electrical cardioversion

Every procedure has risks. The risks of electrical cardioversion include:

  • Creating other kinds of arrhythmias that may be more or less dangerous

  • Short-term (temporary) low blood pressure or slow heart rate

  • Heat damage to the skin

  • Muscle soreness

  • Heart damage (often temporary and with no symptoms)

  • Heart failure

  • Dislodged blood clot that can cause stroke, pulmonary embolism, or other problems

In some cases, healthcare providers lower the risk for blood clots by giving medicine called a blood thinner. You may be given this medicine for 3 to 4 weeks before the procedure. And you may take it for at least 4 weeks after the procedure. Or your healthcare provider may recommend a procedure called transesophageal echocardiography (TEE). This is done just before the cardioversion to screen for an existing blood clot in your heart.

Your own risks may vary based on your age, the type of arrhythmia you have, and your overall health. Ask your healthcare provider which risks apply to you.

After a cardioversion you will need someone to drive you home and around for the next 24 hours. You should not operate heavy machinery for at least 1 day after receiving sedation for a cardioversion.

You should follow up with your healthcare provider to make sure the cardioversion has successfully converted your rhythm. Some people can go back into Afib and may not even be aware their heart rhythm as has changed. You may have a 12 lead ECG at your follow up office appointment to confirm your heart rhythm is still normal.