Implantable cardioverter-defibrillator

An ICD is made up of these parts:

• The pulse generator is about the size of a large pocket watch. It contains a battery and 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.
• Most 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.
• There is a special kind of ICD called a subcutaneous ICD. This device has a lead that is placed in the tissue to the left of the breastbone rather than in the heart. This type of ICD cannot also be a pacemaker.

A cardiologist or surgeon most often 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 clinician will make an incision (cut) through your skin and create space under your skin and muscle for the ICD generator. In most cases, this space is made near your left shoulder.

The clinician will place the electrode into a vein, then into your heart. This is done using a special x-ray to see inside your chest. Then the clinician will connect the electrodes to the pulse generator and pacemaker.

The procedure most often takes 2 to 3 hours.

Some people with certain conditions will have a special device that combines a defibrillator and biventricular pacemaker placed. The pacemaker device helps the heart to beat in a more coordinated fashion.

An ICD is placed in people who are at high risk of sudden cardiac death from an abnormal heart rhythm that is life threatening. These include ventricular tachycardia (VT) or ventricular fibrillation (VF).

Reasons you may be at high risk are:

• You have had episodes of one of these abnormal heart rhythms.
• Your heart is weakened, too large, and does not pump blood very well. This may be from earlier heart attacks, heart failure, or cardiomyopathy (diseased heart muscle).
• You have a type of congenital (present at birth) heart problem or genetic health condition.

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 feel it in most cases.

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. The doctor who manages your ICD care can program your device.

Always tell your health care provider what medicines you are taking, even medicines or herbs you bought without a prescription.

The day before your surgery:

• Let your cardiologist or surgeon 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 breath mints. Rinse your mouth with water if it feels dry, but be careful not to swallow.
• Take the medicines you have been told to take with just a small sip of water.

You will be told 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 they return to their normal activity level. Full recovery takes about 4 to 6 weeks.

Ask your cardiologist or surgeon how much you can use the arm on the side of your body where the ICD was placed. You may be advised not to lift anything heavier than 10 to 15 pounds (4.5 to 6.75 kilograms) and to avoid pushing, pulling, or twisting your arm for 2 to 3 weeks. You may also be told not to raise your arm above your shoulder for several 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 regular checkups so your ICD can be monitored. The cardiologist will check to see if:

• The device is properly sensing your heartbeat
• How many shocks have been delivered
• 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. Most of these devices can also work as a pacemaker.

ICD; Defibrillation

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Updated by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.