An Implantable Cardioverter Defibrillator (ICD) is a pacemaker-like device that continuously monitors your heart rhythm. If it senses there is a problem with the rhythm that is not too serious it delivers a series of painless electrical impulses to correct the heart rhythm. If this doesn't work, or a more serious heart rhythm problem is detected, the ICD will deliver a small electrical shock, known as cardioversion. If this doesn't work, or a very serious problem is detected, the device will deliver a more noticeable shock to the heart, known as defibrillation.
ICDs are generally used in people at high risk of serious rhythm problems in the ventricles (lower chambers) of their heart, the primary cause of sudden cardiac death. In certain patients groups with heart failure, these devices have been shown to prolong survival. Doctors frequently choose to combine an ICD with a CRT in the same device. In this case, the device is termed a CRT-D.
An ICD is usually implanted with a local anaesthetic, just under your collarbone with flexible electrode leads (coated wires) coming from it that are positioned in your heart. The procedure usually takes 1-2 hours.
The electrode lead(s) is inserted into a vein at the shoulder or the base of the neck. The cardiologist guides the lead into the correct chamber of the heart, checking its position on an X-ray screen, and secures it in position with a stitch at your shoulder. The lead is then connected to the pacemaker and the pacemaker is fitted into a small 'pocket', or space, between the skin and the chest muscle. The device is then tested before the wound is closed.
After your ICD has been fitted, you may feel some pain or discomfort and there may be some bruising at the site of the ICD, but these problems usually disappear in a few days. Most people are walking around later the same day and resume normal activities again within 2-4 weeks.
The functioning and battery life of your ICD must be checked regularly at a pacemaker clinic. Depending on the device implanted, a telemonitoring follow up may be proposed to monitor your device, allowing rapid identification of heart rhythm disturbance and technical dysfunction and may improve your care and reduce the need for device clinic visits.
If the battery must be replaced, only the device needs to be replaced (not the leads). The battery usually lasts between 5 and 7 years before it needs to be replaced.
It is important that you let any doctors or dentists know that you have an ICD before going for any procedures. Although most medical and dental procedures are unlikely to interfere with the functioning of your device, some may require precautionary measures that minimise any interference.
ICDs may sometimes be detected by airport security machines, but the functioning of the device is rarely affected, so if you have an ICD you should always inform the security personnel.
Two types of ICDs are used: