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Cardioversion is a procedure used to help return your heart’s rhythm to normal if it’s beating irregularly (called arrhythmia). This information focuses on a type of cardioversion called electrical or direct-current (DC) cardioversion.

You’ll meet the doctor carrying out your cardioversion to discuss your care. It may differ from what is described here, because it will be designed to meet your individual needs.

An arrhythmia (or abnormal heart rhythm) is caused when the normal electrical signals in your heart become faulty. Cardioversion uses an electric shock delivered from a machine called a defibrillator to restore your heart’s rhythm to normal. There are different types of arrhythmia that can be treated with cardioversion. These include atrial fibrillation, atrial flutter and ventricular tachycardia.

Cardioversion isn’t suitable for everyone. Whether it’s right for you will depend on how long you have had arrhythmia, your symptoms and your medical history.

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  • Preparation Preparing for cardioversion

    Your doctor will explain how to prepare for your cardioversion.

    Preparing for an urgent cardioversion

    If you need to have cardioversion urgently, your doctor will give you a medicine to stop your blood clotting, such as heparin. This is called an anticoagulant. You’re likely to receive this through a drip inserted into a vein in your hand or arm.

    You may also have a scan called a transoesophageal echocardiogram to check for blood clots in your heart. To do this, a device called an ultrasound sensor is passed into your oesophagus to look at your heart. Your oesophagus is the pipe that goes from your mouth to your stomach. You’ll have the cardioversion as soon as your doctor has checked it’s safe to go ahead.

    Preparing for a planned cardioversion

    If your cardioversion is planned, there is plenty of time for you to take any medicines your doctor prescribes beforehand. They may prescribe:

    • oral anticoagulant medicines – these help to stop your blood clotting (eg, warfarin)
    • antiarrhythmic medicines – these help to control your heart’s rhythm, making it more likely that cardioversion will work

    You may have some hospital tests before your cardioversion. These will help your doctor decide whether cardioversion is suitable for you. Tests you might have are explained below.

    • Blood tests – for example, to check how well your blood clots.
    • An electrocardiogram (ECG) – this measures the electrical activity in your heart and its rhythm.
    • An echocardiogram – this is an ultrasound scan of your heart. It provides a clear image of your heart muscles and valves, and shows how well your heart is working.
    • A transoesophageal echocardiogram – this is an ultrasound scan of your heart using a sensor put into your oesophagus (the pipe between your mouth and stomach).

    Cardioversion is usually done as a day-case procedure, which means you’ll probably go home the same day. You may be asked to follow fasting instructions beforehand. This means not eating or drinking, typically for about four to six hours before your cardioversion. Follow your doctor’s advice about fasting.

    Your doctor will explain what will happen before, during and after your procedure. This is your chance to understand what will happen. You may want to ask questions about the risks, benefits and any alternatives to the procedure. Noting questions down before your appointment can be helpful, as it might be hard to remember all your questions on the day.

    Get all the information you need to decide whether to have cardioversion. If you choose to go ahead, it’s usual to be asked to sign a consent form.

    When planning ahead for your procedure, remember you’ll need someone to take you home and stay with you afterwards because you’ve had a general anaesthetic.

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  • Alternatives What are the alternatives to cardioversion?

    There may be other treatments available to help regulate your heart’s rhythm. Which ones might be suitable for you will depend upon the type of arrhythmia you have and your general health. Some alternative treatments are listed below.

    • Antiarrhythmic medicines – these are usually given as tablets and can help to control your heart’s rate and rhythm. They can work as well as cardioversion for treating most arrhythmias.
    • Ablation – this is a procedure to stop any faulty electrical signals that your heart is making. It’s often done by placing a thin tube through one of your veins (often one in your groin) into your heart. The heart tissue that is causing the problem can then be treated via this tube.
    • Having a pacemaker fitted – this is a device used to regulate your heart beat.

    Your doctor will advise which treatment options are most suitable for you.

  • The procedure What happens during cardioversion?

    The thought of having an electric shock to your heart might be worrying, but the procedure is short and very safe.

    Cardioversion usually takes about 10 minutes. Just beforehand, you’ll be given a sedative or a light general anaesthetic. Having a general anaesthetic will mean you’re asleep during the procedure, whereas a sedative will make you very drowsy. Once this has taken effect, your doctor will give your heart a brief, controlled electric shock. To do this, they will usually use two pads placed on your chest that come from a defibrillator device.

    Your doctor will monitor your heart rate and rhythm during the procedure. This means they can immediately see whether the procedure has reset your heart to its normal rhythm. Your doctor may give you one or two more electric shocks to reset your heart if the first one doesn’t work fully.

  • Heart treatment on demand

    You can access a range of our health and wellbeing services on a pay-as-you-go basis, including heart treatment.

  • Aftercare What to expect afterwards

    When you wake up from your cardioversion, you may feel tired or unsteady. You’ll need to rest for a few hours until the effects of the anaesthetic or sedation have passed.

    An ECG machine is used to keep an eye on your heart beat while you recover. Once you feel ready and the nurses looking after you are happy, you can get out of bed and walk around. You’ll be able to go home once your heart rhythm is stable and you feel ready to. Be sure to arrange for someone to drive you home and keep an eye on you that day.

    You’ll probably be given a date for a follow-up appointment before you go home.

    Your doctor will prescribe anticoagulant medicines for you to take at home. It’s important you keep taking anticoagulants for as long as your doctor recommends. This is to reduce your risk of getting a blood clot. Follow your doctors instructions and if you’re unsure about anything, ask.

    You’ll need to arrange for someone to drive you home. General anaesthesia can make it harder to coordinate your movements and to think clearly. Therefore, it’s a good idea to have someone stay with you for the first 24 hours, in case you become unwell. Don’t drive, drink alcohol, operate machinery or sign legal documents during this time.

    It’s a good idea to take it easy for a few days after your procedure. Your doctor will give you advice about when you can go back to work and begin exercise again. This timeframe differs from person to person.

    Contact your GP if you notice any changes in your heart beat or your symptoms return. If your arrhythmia has come back after you have had cardioversion, you may need more treatment. See our frequently asked questions for more information about what to do if your arrhythmia returns.

  • Side-effects What are the side-effects?

    Side-effects are the unwanted, but mostly temporary, effects you may get after having a procedure. For example, you may feel sick after the general anaesthetic. After having cardioversion, the skin on your chest may feel slightly sore, from where the shock was given to you.

    Cardioversion can cause your blood pressure to temporarily drop, so you may have a headache or feel dizzy.

    You might also find that the medicines you’re given to take before or after your cardioversion have side effects. Ask your doctor about any risks or side-effects of the particular medicines recommended for you.

  • Complications What are the complications?

    Complications are problems that occur during or after a procedure.

    The possible complications of cardioversion include the following.

    • You may have an unexpected reaction to the anaesthetic or sedation. You’ll be given treatment to help if this happens, but it’s extremely rare.
    • You may develop other problems with your heart rhythm during cardioversion. These are uncommon though and most don’t need treatment.
    • There is a very small risk of having a stroke after cardioversion. A stroke happens when a blood clot which has formed in your heart is released during cardioversion. This then blocks the blood vessels in your heart or brain. You’ll be given anticoagulant medicines before and after your procedure to reduce this risk.
  • Anticoagulant medicines before cardioversion Why do I need anticoagulant medicines before having cardioversion?


    Anticoagulant medicines help to reduce your risk of developing a blood clot. This is important, because having an irregular heart beat can increase your risk of getting a blood clot within your heart.

    More information

    If you have an arrhythmia, it means you have an irregular heart beat. As a result, some of the blood in your heart might not be pushed out of your heart with each beat. The blood that remains may be more likely to clot. If a clot moves through your bloodstream to your brain, it could cause a stroke.

    Your doctor will usually prescribe an anticoagulant medicine (such as warfarin) to help reduce your risk of developing a blood clot. You’ll usually be asked to take this for at least three or four weeks before and after having cardioversion.

    If you have had urgent cardioversion, you’re likely to be given heparin through a vein in your hand or arm. This helps prevent any blood clots forming in your heart. You may have a scan too, to check for blood clots in your heart.

  • Will cardioversion solve my arrhythmia for good? Will cardioversion solve my arrhythmia for good?


    Cardioversion usually works well to correct arrhythmia, at least in the short-term. You might find that your arrhythmia returns in the future. If this happens, you may need to have cardioversion again or a different treatment.

    More information

    Although cardioversion usually works, there is a chance your heart beat will not be corrected by the shock. The likelihood of cardioversion working varies from person to person and the type of arrhythmia you have.

    Some people find that their arrhythmia returns again within a few days, weeks or months. Up to half of people treated with cardioversion for atrial fibrillation get the condition again within a year.

    If your arrhythmia returns after your cardioversion, your doctor may recommend you have the procedure again, or they might recommend a different treatment. The best treatment for you may depend on how quickly your arrhythmia has come back.

  • Medicines after cardioversion Why do I need medicines to help regulate my heart rhythm after cardioversion?


    Cardioversion helps to reset your heart’s rhythm when it goes wrong, but the problem can sometimes happen again. Medicines to help regulate your heart rate and rhythm are known as antiarrhythmic medicines. They are sometimes prescribed if cardioversion doesn’t work or if your arrhythmia might come back after treatment.

    More information

    Your arrhythmia might return in the future, despite you having had cardioversion. Sometimes, an arrhythmia can return days, weeks, or months after you have cardioversion. Anti-arrhythmic medicines can help to prevent this happening. If you have atrial fibrillation, for example, you’re less likely to get arrhythmia again if you take an antiarrhythmic medicine after your cardioversion.

    Examples of antiarrhythmic medicines are beta-blockers, amiodarone and verapamil. For some people, it may be possible to have a tablet to take only if you get symptoms. This means you wouldn’t need to take the medicine regularly.

    Whether your doctor recommends an antiarrhythmic medicine for you, and which one they recommend, will depend on your symptoms and general health.

  • Travel after cardioversion Can I travel in an aeroplane after I have had cardioversion?


    You’ll need to check with your doctor whether or not it’s safe for you to travel by air.

    More information

    Many people with heart problems can still fly in an aeroplane. For example, if you have an arrhythmia but it’s being well controlled, you’ll probably still be able to fly. If you have recently had cardioversion or another hospital procedure, check with your doctor whether it’s safe for you to fly.

    Things your doctor may take into account when advising whether it is safe for you to travel by air include:

    • whether you have recovered fully from your procedure
    • whether you still have an arrhythmia, and if so, what type

    If you have ongoing heart problems and your doctor gives you the okay to travel, let your airline know about your condition. They can make sure any extra safety measures are in place that you might need. Also, check with your travel insurer that you will be covered.

    Your doctor can also let you know about any extra precautions you should take. For example, long journeys can increase your risk of having a blood clot, so wearing compression stockings can reduce this risk.

  • Other helpful websites Other helpful websites


    • Defibrillation and cardioversion. Medscape., published December 2014
    • Synchronized electrical cardioversion. Medscape., published October 2014
    • Practical procedures. Oxford handbook of cardiology (online). Oxford Medicine Online., published May 2012
    • Defibrillation and cardioversion. PatientPlus., published February 2014
    • Cardioversion and atrial fibrillation. AF Association., accessed July 2015
    • Electrical cardioversion. Milan, Italy: SICS; 2014
    • Cardioversion. British Heart Foundation., accessed 22 July 2015
    • Arrhythmias. Oxford handbook of cardiology (online). Oxford Medicine Online., published May 2012
    • Sucu M, Davutoglu V, Ozer O. Electrical cardioversion. Ann Saudi Med 2009; 29:201–06
    • Heart rhythms. British Heart Foundation., published May 2012
    • European Heart Rhythm Association, European Association for Cardio-Thoracic Surgery, Camm AJ, et al. Guidelines for the management of atrial fibrillation. Euro Heart 2010; 31(19):2369–429. doi:10.1093/eurheartj/ehq278
    • Atrial fibrillation: the management of atrial fibrillation. National Institute of Health and Care Excellence (NICE), August 2014.
    • General anaesthesia. PatientPlus., published June 2015
    • Travel and your heart. British Heart Foundation., published February 2015
    • Fitness to fly for passengers with cardiovascular disease. British Cardiovascular Society., published July 2010.
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