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Cardioversion

Published by Bupa's health information team, June 2008.

This factsheet is for people who are planning to have cardioversion, or who would like information about it.

Cardioversion uses either medicine or electric shock, or sometimes both, to help the heart return to its normal rhythm.

Your care will be adapted to meet your individual needs and may differ from what is described here. So it's important that you follow your doctor's advice.

• About cardioversion
• Diagnosis of heart conditions
• What are the alternatives?
• Preparing for your procedure
• About the procedure
• What to expect afterwards
• Recovering from cardioversion
• What are the risks?
• Further information
• Questions and answers
• Related topics
• Sources

About cardioversion

Cardioversion is often recommended as a treatment option for some types of arrhythmia (abnormal heartbeat) such as atrial fibrillation (when electrical signals in the heart are disorganised and the heart beats irregularly) or atrial flutter (when the heart beats too fast). These conditions happen because of problems in upper chambers of the heart (atria).

Cardioversion may also be used to treat ventricular tachycardia (when the heart beats to fast because of problems in lower chambers of the heart, ventricles).

Diagnosis of heart conditions

Symptoms such as breathlessness, chest pains, dizziness, fainting, palpitations and a fluttering feeling in your chest can indicate a heart problem. Conditions of the heart and blood vessels are usually identified and treated by a specialist doctor called a cardiologist.

What are the alternatives?

There are many treatments available to help regulate the heart's rhythm. Some are listed here.

• Medicines - for example, beta-blockers can help control your heart rate and rhythm.
• Surgery (ablation) - a special sensor is passed from the vein in the groin up to the heart and fibres in the relevant heart chambers are frozen or burnt.
• Pacemaker - this helps regulate heartbeat but it's rarely used alone and usually only after burning the main junction box in the heart (AV node) to control atrial fibrillation.

Your doctor will advise which treatment is most suitable for you.

Preparing for your procedure

Your doctor will explain how to prepare for your cardioversion. For example, you will have blood tests to check your blood count, kidney function and to check how your blood clots.

Any medicine you are already taking will be assessed. You will be prescribed anti-clotting medicine (such as warfarin) for several weeks before the procedure. You may also be given medicines (such as beta blockers) to help regulate your heart's rhythm.

Cardioversion is routinely done as an out-patient or day case under sedation or light general anaesthesia. Sedatives help you feel relaxed and drowsy, and general anaesthesia puts you to sleep, during the procedure.

If you are having a general anaesthetic, you will be asked to follow fasting instructions. Typically you must not eat or drink for about six hours before a general anaesthetic. However, some anaesthetists allow occasional sips of water until two hours beforehand.

At the hospital you are likely to have the following tests before a cardioversion.

• Electrocardiogram (ECG) - this measures the electrical activity in the heart.
• Echocardiogram (heart ultrasound scan) - this shows the pumping action of the heart and valves.

Your doctor will usually ask you to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.

About the procedure

The procedure usually takes 10 minutes.

Your doctor will give a brief, controlled electric shock to your heart usually through two pads placed on your chest.

Your heart rate and rhythm is monitored throughout the procedure, so your doctor can see immediately if the procedure has reset your heart to its normal rhythm.

Your doctor may give you up to two more electric shocks to reset the heart if the first attempt is unsuccessful.

What to expect afterwards

You will need to rest until the effects of the anaesthetic have passed. Your nurse will regularly check your heart rate and blood pressure. You will usually be able to go home when you feel ready.

You may feel better immediately if the treatment is successful. Your doctor may prescribe medicines to help maintain a regular heartbeat. You should have someone with you when you are given the instructions for the medicines, as you may not remember the details clearly.

Your doctor may arrange for you to come back at a later date for further treatment if the procedure isn't successful.

You will usually be given a date for a follow-up appointment before you go home.

You will need to arrange for someone to drive you home. You should try to have a friend or relative stay with you for the first 24 hours.

Recovering from cardioversion

Sedation and general anaesthesia temporarily affects your co-ordination and reasoning skills. You must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours after sedation, or for 48 hours after general anaesthesia. If you are in any doubt about driving always follow your doctor's advice and please contact your motor insurer so that you are aware of their recommendations.

You should limit your alcohol, tobacco and caffeine intake, especially after having cardioversion treatment, as these are stimulants and can speed up your heart rate.

Please contact your doctor or GP if you feel any changes in your heartbeat or have any concerns.

What are the risks?

Cardioversion is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.

Side-effects

These are the unwanted but mostly temporary effects of a successful procedure, for example feeling sick as a result of the general anaesthetic.

The skin on your chest may feel a little sore where the shock was administered and you may have a low blood pressure for a few hours after cardioversion.

Complications

This is when problems occur during or after the procedure. Most people are not affected. The possible complications of cardioversion are listed here.

• An unexpected reaction to the anaesthetic - medicines are available to help if this happens.
• Damage to heart muscles - the electrical shocks can affect the way that your heart muscles work and may trigger other arrhythmias.
• Myocardial necrosis (heart tissue death) - if high energy shocks are used, some parts of the heart tissue may die.
• Heart attack or stroke - very rarely, a blood clot can dislodge from your heart during the procedure. There is a risk this may block the blood supply to the heart or brain and trigger a heart attack or stroke. Your doctor will make sure that you are taking the most appropriate anti-clotting medicine to reduce this risk.
• Cardioversion failure - your doctor will be very experienced at performing this type of procedure but, even so, cardioversion does not always restore a normal heart rhythm. The success of cardioversion depends on your medical condition.

The exact risks are specific to you and differ for every person, so we have not included statistics here. Ask your doctor to explain how these risks apply to you.

Further information

• The British Heart Foundation
  08450 70 80 70
  www.bhf.org.uk

 

Related topics

• Arrhythmia (palpitations)
• Beta-blockers
• Echocardiogram
• Electrocardiogram
• Local anaesthesia

Sources

• Atrial fibrillation - guidance 36. National Institute for Health and Clinical Excellence (NICE). June 2006. www.nice.org.uk, accessed 8 April 2008
• What is an arrhythmia? National Heart Lung and Blood Institute. www.nhlbi.nih.gov, accessed 8 April 2008
• Sulke N, Sayers F, Lip GYH. Rhythm control and cardioversion. Heart 2007; 93:29-34. www.bmj.com, accessed 8 April 2008
• Adgey AAJ, Walsh SJ. Theory and practice of defibrillation: (1) Atrial fibrillation and DC conversion. Heart 2004; 90:1493-1498. www.bmj.com, accessed 8 April 2008
• Anaesthesia explained. Royal College of Anaesthetists. www.rcoa.ac.uk, accessed 8 April 2008

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr Tim Cripps DM, FRCP, Consultant Cardiologist, specialist in electrophysiology, Bristol Royal Infirmary, and by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: June 2008.