Implantable Cardioverter-Defibrillator (ICD)

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What is an implantable cardioverter-defibrillator (ICD)?

An implantable cardioverter-defibrillator (ICD) is a small, battery-powered device. It can fix an abnormal heart rate or rhythm and prevent sudden death. The ICD is placed under the skin of your chest. One or two wires (called leads) connect the ICD to your heart.

When is an ICD used?

ICDs are used in people who have had a life-threatening, fast heart rhythm or are at high risk of having one. Heart problems that can make a fast heart rhythm more likely include coronary artery disease, heart failure, and a structural or electrical problem of the heart.

How does it work?

An ICD is always checking your heart for a life-threatening, rapid heart rhythm. The ICD may try to slow the rhythm back to normal using electrical pulses. If the dangerous rhythm doesn't stop, the ICD sends an electric shock to the heart. This restores a normal rhythm. The device then goes back to its watchful mode.

Some ICDs also can fix a heart rate that is too slow. The ICD does this without using a shock. It can send out electrical pulses to speed up a heart rate that is too slow.

Your doctor will program the ICD to send electrical pulses or a shock when needed. Whether you get pulses or a shock depends on the type of ICD, the type of problem that you have, and how the doctor programs the ICD to respond to it.

How is an ICD placed?

Your doctor will put the ICD under the skin in your chest during minor surgery. You will likely have medicine to make you feel relaxed and sleepy during the surgery.

Your doctor makes a small cut (incision) in your upper chest. The doctor puts one or two leads (wires) through the cut. The leads go into a large blood vessel in the upper chest. Then your doctor guides the leads through the blood vessel into your heart. Your doctor connects the leads to the ICD and places it in your chest. Then the incision is closed. Your doctor also programs the ICD.

Most people spend the night in the hospital, just to make sure that the device is working and that there are no problems from the surgery.

How does an ICD shock feel?

The shock from an ICD hurts briefly. But the shock is a sign that the ICD is doing its job. It's there to save your life.

People feel it in different ways. It's been described as feeling like a punch in the chest. You won't feel any pain if the ICD uses electrical pulses to fix a heart rate that is too fast or too slow.

There's no way to know how often a shock might occur. It might never happen. It's possible that the ICD could shock your heart when it shouldn't. If that were to happen, you would have pain.

Shocks and the fear of shocks can make some people worry a lot. But you can take simple steps to feel better about having an ICD. These steps include having your ICD checked regularly by your doctor and making an action plan for what to do if you get shocked.

How can you live well with an ICD?

You can live a normal life with your ICD. Here are a few tips for living well with your ICD.

  • Use certain electric devices with caution. Some electric devices have a strong electromagnetic field. This field can keep your ICD from working right for a short time. Check with your doctor about what you need to avoid and what you need to keep a short distance away from your ICD. Many household and office electronics don't affect your ICD.
  • Be sure that your health professionals know that you have an ICD. This includes any doctor, dentist, or other health professional you see.
  • Always carry a card that tells what kind of device you have.
  • Wear medical alert jewelry that says you have an ICD. You can buy this at most drugstores.
  • If you get a shock, follow your action plan for what to do.
  • Ask your doctor what sort of activity and intensity is safe for you. You can lead an active life with an ICD.

As you plan for your future and the end of life, be sure to include plans for your ICD. You can make the decision to turn off your ICD as part of the medical treatment you want at the end of life.


Current as of: June 24, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.