ICD stands for implantable cardioverter defibrillator. If your doctor has suggested that you need an ICD you may have experienced or may be at risk of experiencing an abnormal, fast heart rhythm. An ICD constantly monitors your heart rhythm and can deliver various electrical impulses to correct potential problems. It is made up of a small pulse generator, contains a battery and electronic circuits, and sophisticated leads that connect the generator to the heart. An ICD, like a pacemaker, is usually placed under the skin below your collarbone.

S-ICD system

A traditional implantable cardioverter defibrillator (ICD), has one or more leads that enter the heart allowing the device to provide pacemaker functions as well as defibrillation. Conversely, an S-lCD has no leads connected to the heart, presenting a less invasive option for patients not in need of any cardiac pacing. For example, if your doctor has told you that you have, or are at risk of, a slow heartbeat, an S-ICD would not be an appropriate option. The implanting doctor will be able to advise whether or not a traditional ICD or an S-ICD is suitable.

Visit S-ICD dedicated website

Most modern ICDs have three main functions:

  1. If your heart rhythm is too slow, the device can give your heart extra support by working as a normal pacemaker (anti-bradycardia pacing).
  2. If your heart beats too fast, the ICD can return your heart back to a normal rhythm (anti-tachycardia pacing or ATP).
  3. If the anti-tachycardia pacing doesn’t bring your heart back to a normal rhythm, or if the ICD senses a faster, dangerous rhythm called ventricular fibrillation, the ICD can then give a shock (defibrillation) to the heart to restore normal rhythm.

Some modern ICDs only provide defibrillation.  These are suitable for patients not in need of cardiac pacing, and are particularly of interest to patients not wishing to bear the risks associated with having leads threaded through the veins to the heart.


icd - implantable cardioverter defibrillator

This procedure is performed under either a general anaesthetic or a local anaesthetic with sedation. The pulse generator is connected to either one or two leads that, for most models, pass through a vein into the heart. The doctor may test the device during the procedure to ensure it is working correctly. The implant should take between one and two hours and any stitches that may need to be removed will be done at your GP surgery.

You will probably be allowed to go home the next day provided your ICD is checked and there are no complications. You will be given an ICD identity card, emergency information and instructions at this point. You will also be given a helpline number should you have any queries later on.

Normally an ICD battery lasts between six and nine years and the replacement procedure will usually involve changing the ICD generator, not having new leads implanted.

Living with an ICD

Some patients have reported that having shocks can feel like they have been suddenly kicked or punched in the chest. These shocks can be quite painful but the pain will only last for a few seconds, others may not feel anything.

If you do feel unwell after a shock, or if your device has given you several shocks, please dial 999 for an ambulance. Show the paramedics your identity card along with any emergency instructions; this will inform them of exactly which type of device you have and what the best course of action will be.

You should always contact your ICD centre if you think you have had a shock.

Physical activity with an ICD

For most patients it is safe to exercise and to take part in sport. Indeed, research has shown that physical activity and exercise are beneficial for people fitted with an ICD.

Individual cases are influenced by the cause and type of your heart rhythm problems and the type of exercise you perform. Your clinicians will be able to advise you of any exercise-related information that is specific to your situation. The likelihood of an arrhythmia is no greater during moderate exercise than during resting but there are certain types of exercise that may increase the risk. If you exercise vigorously from rest, without a warm-up, and immediately cease exercise, with- out a cool down or active recovery period you increase the likelihood of arrhythmia.

Your ICD

Your ICD can detect an abnormal heart rhythm in a number of ways, one of which relates to the speed of the heart during the arrhythmia. Most arrhythmias treated with ICDs will be significantly faster than your normal heart rate would reach, even with strenuous exercise. Occasionally however, the ICD needs to be programmed to recognise abnormal heart rates that are close to those that can be achieved with exercise. For this reason, it is worthwhile to check how your ICD is programmed before anything other than recreational exercise or exercise to lose weight.

If you are concerned about your safe exercise level, you should ask your cardiologist, cardiac physiologist or arrhythmia/ICD nurse specialist.

Dos and don’ts

For most forms of exercise it is recommended that someone who knows that you have an ICD accompanies you. You should ensure that you have your ICD card with you AT ALL TIMES, in case you need to be taken to hospital for any reason.

You should not undertake any contact sports. Although the ICD itself is very tough, bruising or breaking the skin over the implant site may lead to infection. Swimming can be undertaken once the implant wound has healed fully.

You will not be able to take part in any form of competitive motor sport, as you will not be eligible for an appropriate licence. Regular driving should be discussed with your cardiologist. Latest regulations for ICD patients can be found on the DVLA website:http://www.direct.gov.uk/en/Motoring/DriverLicensing/MedicalRulesForDrivers/index.htm

You should also avoid any sport (or indeed any situation) where you might be exposed to strong magnetic or electrical fields or a powerful radio source (radio-controlled planes, cars, boats, etc may be a problem).

Be gentle

It is likely that your underlying heart condition will have more influence on your ability to exercise than the presence of your ICD. Your underlying heart condition may limit your exercise due to shortness of breath, fatigue or chest pain - these should not be ignored.

Physical activity and exercise should be progressed slowly. The key is to avoid becoming too breathless during exercise, as this will sap your strength and make your heart work too hard. All exercise sessions should start with a warm-up and finish with a cool-down period, both of which should last for approximately ten minutes, so that your body and heart have time to adjust.

In general, most exercises should be performed standing, with horizontal (lying down) and seated arm exercises kept to a minimum. Seated arm exercise with weights may increase the workload on your heart too much leading to an increased likelihood of an arrhythmia.


Physical activity and exercise can be very useful in helping people with an ICD to become more confident and active. Exercise as described above is safe with a warm up and cool down period.

What about driving?

There may be some restrictions on driving; you can access DVLA guidelines on:


Current rules (2013) place a six month ban on driving following implant of secondary prevention ICD or delivery of an appropriate shock. For primary prevention ICDs the rules are a one month restriction. lt is very important that you discuss this with your nurse, physiologist or doctor at your lCD centre who will explain this in more detail and let you know what is specific to your circumstances.

It is strongly recommended that you inform your insurance company.

For specific and detailed information please see the DVLA website

More information

Many ICDs are fitted to prevent arrhythmias from deaths from sudden cardiac arrest (SCA).  

A recent alternative to ICDs that require leads attached to the heart is available in some countries.  Called subcutaneous ICDs (S-ICD), the new devices are able to defibrillate the heart with only a lead that is placed just beneath the skin instead of into the heart.  The are not suibable for all patients.

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