What are are Implantable cardioverter defibrillators

People who have a particular sort of abnormal heart rhythm, called pulseless VT (ventricular tachycardia) or VF (ventricular fibrillation), may need to have a device fitted called an ICD. Ventricular tachycardia is when the heart beats too fast, and this means that there is not enough time for the heart to fill with blood properly between beats (contractions), so not enough blood is pumped round the body.

In ventricular fibrillation, the heart rhythm is so abnormal that the heart no longer contracts, but quivers instead. This results in death, unless an electrical shock is given to the heart to restart it.

An ICD works by constantly monitoring the heart rhythm. If ventricular tachycardia is detected, the ICD will try to correct it. If this does not work, the ICD will try to bring the heart back to normal by giving it a small, controlled electrical shock. If this fails, the ICD will deliver a larger shock, which is known as defibrillation.

If the ICD detects ventricular fibrillation, it will defibrillate the heart immediately.

As with pacemakers, ICDs are implanted in hospital, usually under local anaesthetic and complications are rare. Like pacemakers, you will need to avoid things that can interfere with the way in which the ICD works, such as airport security systems.