Arrhythmias
Having an arrhythmia or abnormal heart rhythm means your heart is beating too fast, too slow or in an irregular pattern. Learn about symptoms, diagnosis and treatment for arrhythmias.
What is cardioversion?
Cardioversion is a treatment used to get your abnormal heart rhythm (also known as arrhythmia) back to a normal pattern.
There are two types of cardioversion; electrical cardioversion and pharmacological cardioversion (also known as chemical cardioversion).
Pharmacological cardioversion is done using medicine. You may swallow the medicine or receive it through an intravenous infusion (also known as an IV). An IV is when medicine is directly injected into your veins.
Chemical cardioversion can work in minutes, hours or even days.
Electrical cardioversion is done using an external defibrillator to send controlled electric signals to your heart through electrodes (or sticky pads) placed on the chest. It is sometimes called DC cardioversion or direct current cardioversion.
Cardioversion is usually planned in advance. But sometimes it may be done in an emergency setting if the symptoms are severe.
How to prepare for cardioversion
Your doctor will give you detailed instructions on what to do before your cardioversion. They may ask you to avoid eating on the day of your procedure.
Attend your appointment with little or no jewellery as they will ask you to take it off. You should also avoid applying any oil or lotion on your chest.
Continue your regular medication as usual unless your doctor asks you to stop
In some cases, you might need to have a transoesophageal echocardiography test before your cardioversion procedure to check for blood clots in your heart.
What happens during cardioversion?
During an electrical cardioversion procedure:
- you'll be given a short-acting general anaesthetic so you will be asleep and completely unaware of the procedure
- a doctor or nurse will put large sticky pads on your chest. If there is hair in the way, it might get shaved
- the pads are connected to a defibrillator and a minimal amount of electric current will be delivered through your heart
- the machine monitors your heart rhythm throughout the procedure so the healthcare team can see straight away if the cardioversion was successful.
The procedure usually lasts a few minutes.
Speak to your healthcare team if you have any worries or questions about your procedure.
Have a look at the below video to find out what happens during a typical cardioversion procedure:
What happens after cardioversion?
After your procedure, you will be closely monitored until the anaesthetic has worn off. It is normal to feel sleepy and some tenderness on your chest.
Your doctor or nurse will discuss the results of the cardioversion with you. You will likely go home the same day.
In the first 24 hours after your procedure, you should not drink alcohol, drive, or operate heavy machinery.
Ask your doctor if you should continue with your medication as usual or if you need to make some changes. It is also important to ask when you can go back to work and when to start exercising again.
Life after cardioversion
For most people, cardioversion restores their heartbeat to normal.
Your doctor may recommend you take blood thinners for a few weeks even if you do not have any blood clots.
If you are still breathless after cardioversion, tell your doctor immediately. You should also speak to your doctor if your other symptoms before the procedure come back.
There’s a chance your heartbeat will not be corrected by cardioversion and that your arrhythmia comes back. If this happens, your doctor may recommend you have the procedure again. Usually after a few cardioversions, they’ll recommend a different treatment.
What are the risks of having a cardioversion?
Complications after cardioversion are rare but there may be some temporary side effects such as:
- it might not work
- skin rash from the electrodes
- allergic reaction to the medication
- skin burns on your chest
- blood clots in your heart may break and cause a stroke. This is very rare.
If you have any questions or worries about side effects, speak to your doctor.
Electric cardioversion is different from typical defibrillation, an emergency procedure that is done when the heart stops. The shocks used in defibrillation are more powerful than those used in DC cardioversion.
Researching abnormal heart rhythms
Your donations help us fund vital research into the causes and treatment of heart and circulatory conditions, including the work of BHF Professor Barbara Casadei, who is pioneering work to improve our understanding of atrial fibrillation, the most common arrhythmia in the UK.
Heart Helpline and other support
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Learn how we make our health content.More information
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Tests for heart rhythm problems
If you experience heart rhythm problems, or symptoms such as dizzy spells or blackouts, your doctor may suggest you have one of these tests. Find out more.