Treatment: External Cardioversion

External cardioversion is an outpatient procedure which is used to restore normal heart rhythm.

To book offline, call our Heart Health centre directly on: 020 3653 2005


What is external cardioversion?

External cardioversion is a procedure to restore your heart rhythm back to a normal rhythm. This procedure is often used for atrial fibrillation, atrial flutter, ventricular tachycardia and ventricular fibrillation.

This can provide relief from the symptoms of these conditions which include palpitations, tiredness and breathlessness

What does external cardioversion involve?

External cardioversion involves connecting you to a defibrillator machine that gives a controlled electric shock to your heart to make it beat normally again.

The procedure is performed under a short general anaesthetic, so you are asleep throughout. Electrodes connected to a defibrillator machine are placed on your chest, sometimes your chest and back. One or more controlled electric shocks are given to restore a normal heart rhythm.

How should you prepare for an external cardioversion?

Your OneWelbeck consultant cardiologist will talk you through the procedure and answer any questions you may have at a consultation before you have treatment. 

They will also give you detailed instructions on how to prepare for your cardioversion, such as avoiding eating on the day of the procedure.

You may also need to have an ECG, echocardiogram (ultrasound scan of the heart) or wear a heart monitor for 24 hours before having the procedure to check that your heart rhythm is still abnormal. Your consultant will arrange this for you. 

You should come to your appointment wearing little or no jewellery as you will be asked to remove it. You should also avoid applying any oils or moisturisers to your chest.

The procedure itself takes around 10 minutes to perform but you should plan to spend around four to six hours in total at OneWelbeck to allow time for procedure preparation and your recovery.

What are the risks associated with an external cardioversion?

Risks of external cardioversion are rare. However, the potential risks of the procedure to be aware of include:

  • Blood clots 
  • Minor burns and chest discomfort at the site of the electrode pads 
  • Nausea from the anaesthetic
  • Dizziness from a drop in blood pressure

Your consultant will talk you through any potential complications before the procedure and answer any questions you have.

What is the recovery process for an external cardioversion?

After the procedure, you will spend an hour or so in the recovery room where you will be monitored closely. You will feel sleepy as the anaesthetic wears off and may feel some aching and tenderness in your chest. 

At OneWelbeck, external cardioversion is performed as an outpatient procedure, so you will be able to go home on the same day. However, it is important that in the first 24 hours after your treatment you do not drink alcohol, drive, or operate heavy machinery, while the anaesthetic wears off completely. 

Your consultant will review you at a follow-up consultation. 

Treatment Programme
External Cardioversion


Health Insurance

This service or treatment is generally covered by most health insurance policies. You are responsible for checking your insurance policy cover, and you may need a referral letter. Check which insurance companies are covered.


Doctor Referral Only

You will generally need to get a referral letter from your NHS GP, Private GP, or other doctor to access this service or treatment. Find out more including how we can assist you


Self-Pay Available

This treatment is available for self-paying users. If you would like to see more information on pricing visit our pricing and payments page.


Consultation Required

For this treatment you will need to have a 1-to-1 consultation at OneWelbeck first. To book in with our team of expert clinicians or to find out more about the process contact the relevant centre team.

External Cardioversion Specialists

Our Heart Health specialists at OneWelbeck in London are leaders in their field. They are equipped with the latest diagnostic medical technology at custom-built, day-case facilities to investigate any symptoms and ensure you receive the best available care.