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Published by Bupa's health information team, June 2008.
This factsheet is for people who have had ventricular fibrillation, or who would like information about it.
Ventricular fibrillation is an abnormal heart rhythm (arrhythmia) which causes the heart to quiver rather than beat. This means the heart is unable to pump blood. If prompt emergency treatment isn't given, then the heart will stop completely. This results in death.
About ventricular fibrillation
Your heart is a muscular pump, responsible for delivering blood to the rest of your body. Your heartbeat is produced by electrical impulses, which start in the upper chambers of your heart (the atria) and are transmitted to the lower chambers (the ventricles). The impulses cause your heart to contract and pump blood around the rest of your body.
In ventricular fibrillation, electrical impulses start firing from multiple sites in the lower chambers of the heart very rapidly and in an irregular rhythm. This makes the heart quiver and unable to beat properly. If prompt treatment isn't given, your heart will stop beating altogether (cardiac arrest). This is fatal.
Ventricular fibrillation most commonly happens in people who have coronary heart disease - when the arteries supplying the heart become narrowed.
The electrical impulses in a normal heart and a heart with ventricular fibrillation
Symptoms of ventricular fibrillation
Someone who has ventricular fibrillation will lose their pulse and will quickly become unconscious and stop breathing.
You should call for emergency medical help immediately if you witness someone collapse and stop breathing.
Causes of ventricular fibrillation
Causes of ventricular fibrillation include:
coronary heart disease and heart attack - this is the main cause of ventricular fibrillation
- certain drugs to treat arrhythmias
- a lack of oxygen
- a condition called Wolff-Parkinson White syndrome
- electrical accidents
- inherited heart conditions
Treatment of ventricular fibrillation
It is important that someone with ventricular fibrillation gets emergency medical help as soon as possible, to give them the best chance of survival. If someone collapses and stops breathing, you should call for emergency help straight away.
Emergency life support
Cardiopulmonary resuscitation (CPR)
Cardiopulmonary resuscitation (often shortened to CPR) means giving chest compressions and rescue breaths (mouth-to-mouth breathing) to someone who has stopped breathing or whose heart has stopped beating. It can buy the casualty more time until doctors or paramedics arrive. You can find out exactly how CPR is carried out in our topic on Emergency life support for adults.
Automated external defibrillators
A process called defibrillation is needed to stop ventricular fibrillation. Defibrillators deliver an electric shock to the chest, and so indirectly to the heart. This can stop the abnormal electrical activity and restart the normal rhythmic heartbeat.
An automated external defibrillator (AED) is a machine that can be used by suitably trained members of the public to assist in resuscitation. They are sometimes available in public places, such as offices, shopping centres, railway stations and on aeroplanes. AEDs analyse a casualty's heart rhythm through pads connected to the chest area, and deliver an electric shock if ventricular fibrillation is detected. They give spoken instructions and are easy for people without formal medical training to use.
There will normally be a sign to indicate if an AED is available in a public place. If one is available, an appropriately trained person (normally a member of staff at the site) should be summoned straight away to use the AED. CPR should be continued until the AED is retrieved and attached.
When a paramedic or doctor arrives, he or she will use a defibrillator, if an AED was not previously available, to give a shock to the person's heart. This may need to be done a number of times. The paramedic or doctor will also continue to carry out CPR, and may give an injection of adrenaline.
When CPR is carried out by a paramedic, or in hospital by a doctor or other health professional, a ventilation device such as a face mask with oxygen will be used to help the casualty breathe, rather than mouth-to-mouth resuscitation.
If you have had ventricular fibrillation, you will be taken to an intensive care unit or cardiac care unit in hospital once your normal heartbeat has been restored. You will probably need to stay in this unit for a few days.
You may have the following while in the intensive care or cardiac care unit:
- a breathing tube inserted into your windpipe (trachea) via your nose or mouth, to help with your breathing
- a cannula (a fine plastic tube) inserted into an artery, so that your blood pressure can be monitored continuously
- sedation - a medicine to help you feel relaxed and less anxious
- a drip into a vein in your arm, to give you fluids and drugs to increase your blood pressure
- drugs to reduce fever (antipyretics) or a saline drip to keep your temperature down
- a catheter (a tube to drain urine from your bladder into a bag)
It can be upsetting to see a friend or relative in intensive care. However, it's important to remember that your friend/relative will be getting the best possible treatment, including sedatives to help them relax and pain relief.
When you have recovered from the initial attack, you will be transferred to a cardiology ward, where you will stay for about a week. You will have various tests to try and find out what caused your ventricular fibrillation. These may include the following.
- An electrocardiogram (ECG). This is a test that measures the electrical activity of your heart to see how well it is working.
- Blood tests, including tests for a protein called troponin, which can show if damage to the heart has occurred.
- An echocardiogram. This is a test that uses ultrasound to produce a moving image of the inside of your heart.
- A coronary angiogram - where a dye visible on X-rays is injected into your coronary arteries to show up any narrowing or blockages.
- An MRI scan. This uses magnets and radiowaves to produce detailed images of the heart.
- An electrophysiological study, where your heart is stimulated in order to identify the part of the heart that caused the abnormal heart rhythm.
If the tests show that you had ventricular fibrillation because of a heart attack, then you are unlikely to have another ventricular fibrillation episode. You will get standard treatment for a heart attack, but will not need any special treatment for your heart rhythm.
However, if your ventricular fibrillation was not associated with a heart attack or other obvious treatable cause, you will need treatment to prevent it from happening again. Only a small number of people who have ventricular fibrillation are found to have no apparent problem with the heart. In these cases, the abnormal heartbeat is thought to be due to a genetic fault. Your family may also need to be screened to check whether they are at risk.
If you need treatment to prevent ventricular fibrillation, your doctor may advise you to have an implantable cardioverter defibrillator (ICD) and prescribe you some medicine. If you had ventricular fibrillation at the time of a heart attack, which was caused by one of the blood vessels to your heart becoming blocked, you will not usually need an ICD. Most other episodes of ventricular fibrillation will mean that you do need an ICD.
Medicines to prevent ventricular fibrillation include amiodarone and beta blockers.
Implantable cardioverter defibrillator
An ICD is a device that can monitor your heart rhythm and return your heartbeat to normal if it detects a problem. The device is implanted just beneath the skin below your collarbone and delivers an electrical impulse (shock) via wires leading to your heart.
The ICD is normally fitted under sedation and local anaesthetic. This means you will feel relaxed and feeling from the area will be blocked. You will not feel any undue discomfort during the procedure.
You will usually need to stay in hospital overnight. The wound should heal in a few days, but you will be advised to avoid strenuous activity, especially activity involving moving your left arm, for about six weeks. This is in case the leads of the ICD are displaced.
- Kasper DL, Fauci AS, Longo DL, et al. Harrison's Principles of Internal Medicine: McGraw-Hill, 2005:1354
- The use of Automated External Defibrillators. Resuscitation Council UK, 2005. www.resus.org.uk
- Frequently asked questions about the national defibrillator programme. Department of Health. www.dh.gov.uk, accessed 11 March 2008
- Resuscitation guidelines: adult advanced life support. Resuscitation Council UK, 2005. www.resus.org.uk
- Treatments and procedures in an ICU. The Intensive Care Society. www.ics.ac.uk, accessed 7 March 2008
- Grubb NR, Managing out-of-hospital cardiac arrest survivors: 2. Cardiological perspective. Heart, 2001; 85:123-124
- Tests for heart conditions. British Heart Foundation, May 2004, Health information series number 9. www.bhf.org.uk
- British National Formulary (BNF). BMJ Publishing Group, 2007. 54
- Tachycardia. Arrhythmia Alliance. www.heartrhythmcharity.org.uk, accessed 8 March 2008
- ICDs. Arrhythmia Alliance. www.heartrhythmcharity.org.uk, accessed 6 March 2008
- Implantable cardioverter defibrillators (ICDs). British Heart Foundation, October 2005. www.bhf.org.uk
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. It has also been reviewed by Arrhythmia Alliance. 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