An implantable cardioverter-defibrillator (ICD) is a device that detects any life-threatening, rapid heartbeat. If such a heartbeat, called an arrhythmia, occurs, the ICD quickly sends an electrical shock to the heart to change the rhythm back to normal. This is called defibrillation.

An ICD is made of these parts:

• The pulse generator is about the size of a large cookie. It contains a battery and the electrical circuits that read the electrical activity of your heart.
• The electrodes are wires, also called leads, that go through your veins to your heart. They connect your heart to the rest of the device. Your ICD may have 1, 2, or 3 electrodes.
• All ICDs have a built-in pacemaker. Your heart may need pacing if it is beating too slowly or too fast, or if you have had a shock from the ICD.

A surgeon will insert your ICD when you are awake. The area of your chest wall below your collarbone will be numbed with anesthesia, so you will not feel pain. The surgeon will make an incision (cut) through your skin and create space under your skin and muscle for the ICD generator. Usually this space is made near your left shoulder.

Using special x-ray to see inside your chest, the surgeon will place the electrode into a vein, then into your heart. Then the surgeon will connect the electrodes to the pulse generator and pacemaker.

The procedure usually takes 2 to 3 hours.

An implantable cardiac defibrillator is placed in people who are at high risk of sudden cardiac death. Reasons you may be at high risk are:

• You have had life-threatening bouts of ventricular tachycardia (VT) or ventricular fibrillation (VF).
• Your heart is weakened, too large, and does not pump blood very well. This may be from earlier heart attacks, heart failure, or cardiomyopathy (a diseased heart muscle).
• Certain congenital (present at birth) heart problems or genetic health conditions

See also:

• Heart attack
• Heart failure

Risks for any surgery are:

• Blood clots in the legs that may travel to the lungs
• Breathing problems
• Heart attack or stroke
• Allergic reactions to medicines (anesthesia) used during surgery
• Infection

Possible risks for this surgery are:

• Wound infection
• Injury to your heart or lungs
• Dangerous heart arrhythmias

An ICD sometimes delivers shocks to your heart when you do not need them. Even though a shock lasts a very short time, you can usually feel it.

This and other ICD problems can sometimes be prevented by changing how your ICD is programmed. It can also be set to sound an alert if there is a problem. Your electrophysiologist, the doctor who manages your ICD care, can program your device.

Always tell your doctor or nurse what drugs you are taking, even drugs or herbs you bought without a prescription.

The day before your surgery:

• Always let your doctor know about any cold, flu, fever, herpes breakout, or other illness you might have.
• Shower and shampoo well. You may be asked to wash your whole body below your neck with a special soap.
• You may also be asked to take an antibiotic, to guard against infection.

On the day of the surgery:

• You will usually be asked not to drink or eat anything after midnight the night before your surgery. This includes chewing gum and using breath mints. Rinse your mouth with water if it feels dry, but be careful not to swallow.
• Take your drugs your doctor told you to take with just a small sip of water.

Your doctor or nurse will tell you when to arrive at the hospital.

Most people who have an ICD implanted are able to go home from the hospital in 1 day. Most quickly return to their normal activity level. Full recovery takes about 4 to 6 weeks.

When you leave the hospital, you will be given a card to keep in your wallet. This card lists the details of your ICD and has contact information for emergencies. You should always carry this wallet card with you.

You will need to make regular visits to the doctor so your ICD can be monitored. The doctor will check to see if the device is properly sensing your heartbeat, how many shocks have been delivered, and how much power is left in the batteries.

Your ICD will constantly monitor your heartbeats to make sure they are steady. It will deliver a shock to the heart when it senses a life-threatening rhythm. This device can also work as a pacemaker.

Epstein, A E, DiMarco, J P, Ellenbogen, K A, Estes, N A, 3rd, Freedman, R A, Gettes, L S, et al. (2008). "ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices): developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons." Circulation;117(21): e350-408.

Hayes DL, Zipes DP. Cardiac pacemakers and cardioverter-defibrillators. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 34.