What is an implantable cardioverter defibrillator?
An implantable cardioverter defibrillator, or ICD, is a small device placed under the skin below the collarbone with one or more fine wires running to the heart. It watches every heartbeat, and if it detects a dangerously fast rhythm that could cause sudden death it treats it automatically, either with a rapid burst of painless pacing or, if that fails, with an internal electric shock that resets the heart. Every ICD also works as an ordinary pacemaker if the heart beats too slowly.
Why is it done?
An ICD is recommended for people at meaningful risk of a life-threatening rhythm: those who have already survived a cardiac arrest or a dangerous fast rhythm, and those whose heart muscle is significantly weakened by a previous heart attack, cardiomyopathy or an inherited condition. It does not make the heart stronger and it does not prevent a rhythm from starting, but it is the most reliable way we have of stopping such a rhythm within seconds, wherever you are.
What happens on the day?
You come in fasting, usually on the morning of the procedure, and receive antibiotics through a drip. In the catheterisation laboratory the skin below the collarbone is numbed with local anaesthetic and you are given sedation, so you are drowsy and comfortable. A small cut is made, and the wire is guided along a vein into the heart under X-ray. The wire is tested to check its position and, if required, the device is tested. It is then connected to the ICD, which is placed in a pocket under the skin, and the cut is closed with stitches. It usually takes one to two hours.
What to expect afterwards
Most patients stay one night and have a chest X-ray and a device check before discharge. The site is bruised and tender for a week or two; keep it dry until healed, avoid raising that arm above shoulder height and avoid heavy lifting for the period your doctor advises. Driving is restricted for a time, and the rules are stricter if the ICD was fitted after a cardiac arrest. You will be given a device identification card to carry, and you should show it at airport security and before any operation or MRI scan. Mobile phones, microwaves and household appliances are safe. The device is checked at regular intervals, sometimes remotely, and the battery lasts several years before it is replaced.
Possible complications
Bruising or a blood collection at the pocket is common and usually settles. Infection is uncommon but important, and may require antibiotics or removal of the device. The lung can occasionally be nicked when the vein is found, allowing air to leak around the lung, which may need a drain. A wire can move, break or stop working properly and need to be repositioned or replaced. The most troublesome long-term problem is an inappropriate shock, when the device shocks you for a fast but harmless rhythm; this is frightening but not dangerous, and the settings or your medication can usually be adjusted. Rarely the heart is injured during implantation, causing bleeding around it. Many patients also need time to adjust emotionally to living with an ICD, and we will support you with that.
This information does not replace a consultation. Please discuss your own risks and options with your cardiologist.