This page will give you information about an external cardioversion. If you have any questions, you should ask your GP or other relevant health professional.
You can also download and print a PDF version of this factsheet, with space for your own questions or notes.
What is an external cardioversion?
An external cardioversion is a procedure to treat an abnormal heart rhythm. It involves connecting you to a defibrillator machine that gives a controlled electric shock to make your heart beat normally again.
Your heartbeat is controlled by electric impulses from a group of cells on your heart called the sinus node.
When your heart beats normally, the electric impulses cause the upper collecting chambers (atria) and lower pumping chambers (ventricles) to contract and relax in a co-ordinated way.
An external cardioversion is usually recommended to treat atrial fibrillation, where the atria contract too fast and in an unco-ordinated way.
What are the benefits of an external cardioversion?
Atrial fibrillation prevents your heart from pumping effectively. This can cause you to get palpitations (your heart beating a few extra times), and to feel breathless and tired. It can also sometimes cause you to have chest pain, dizziness, or to collapse.
Are there any alternatives to an external cardioversion?
Medication can be used to treat some symptoms of atrial fibrillation and reduce the risk of having a stroke but medication may not be as effective as an external cardioversion.
You may be able to have a catheter ablation. This uses heat to create scars that prevent the abnormal electric impulses from affecting your heart.
What does the procedure involve?
External cardioversion usually takes 10 minutes and is usually performed under a general anaesthetic.
The healthcare team will place large sticky pads on your front and back, which will be connected to a defibrillator machine.
Your heart specialist will use the machine to give you a controlled shock to make your heart beat normally again.
What complications can happen?
- change in your heart rhythm
- low blood pressure
- fluid collecting on your lungs
- allergic reaction
How soon will I recover?
You should be able to go home the same day. You should be able to return to normal activities after about 2 days.
Do not drink alcohol or caffeine.
Regular exercise should improve your long-term health. Before you start exercising, ask the healthcare team or your GP for advice.
Atrial fibrillation can cause you to get palpitations and feel breathless, and increases the risk of a blood clot developing in your heart. Having an external cardioversion may improve your symptoms by giving you a shock to make your heart beat normally again.
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Last reviewed: September 2018