An ICD is a battery-powered device that can fix an abnormal heart rate or rhythm and prevent sudden death. The ICD is placed under the skin of your chest. It’s attached to one or two wires (called leads). Most of the time, these leads go into the heart through a vein. The lead is sometimes placed under the skin so it lies near your heart.

An ICD is always checking your heart rate and rhythm. If the ICD detects a life-threatening rapid heart rhythm, it tries to slow the rhythm back to normal using electrical pulses. If the dangerous rhythm does not stop, the ICD sends an electric shock to the heart to restore 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 so without using a shock. It can send out electrical pulses to speed up a heart rate that is too slow.

Whether you get pulses or a shock depends on the type of problem that you have and how the doctor programs the ICD for you.

Your doctor will put the ICD in your chest during minor surgery. You will not have open-chest surgery. You probably will have local anesthesia. This means that you will be awake but feel no pain. You also will likely have medicine to make you feel relaxed and sleepy.

Your doctor makes a small cut (incision) in your upper chest. Your doctor puts the ICD leads through the cut. For one type of ICD, your doctor puts one or two leads (wires) in a large blood vessel and threads them into the heart. For another type, the lead is placed under the skin so that it lies near your heart. Your doctor places the ICD under the skin of your chest. He or she attaches the leads to the ICD. Then the cut will be closed with stitches. Your doctor also programs the ICD.

In some cases, the doctor may be able to put the ICD in another place in the chest so that you don’t have a scar on your upper chest. This would allow you to wear clothing with a lower neckline and still keep the scar covered.

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.

You may be able to see a little bump under the skin where the ICD is placed.

The shock from an ICD hurts briefly. It’s been described as feeling like a punch in the chest. But the shock is a sign that the ICD is doing its job to keep your heart beating. 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. The shock could make you fall out of bed, and that could injure you.

In rare cases, the shock could cause the heart to quiver, or flutter, and stop pumping blood. This is called ventricular fibrillation (say “ven-TRICK-yuh-ler fib-ruh-LAY-shun”), which can be deadly. If this happened, the ICD would shock your heart again to stop the fluttering.

Many people say that they have a good quality of life with an ICD. But shocks—and the fear of shocks—can make some people worry too much. They may be afraid all the time that the ICD might shock them. This worry can reduce a person’s quality of life.

An ICD can help lower the risk of sudden death from a dangerous heart rhythm.

• For people who have survived a life-threatening heart rhythm: Studies have shown that an ICD can lower the risk of death more than heart rhythm medicine can. In one study, ICDs lowered the number of deaths from 18 out of 100 people to 11 out of 100. ^{footnote 1}
• For people who are at risk for a life-threatening heart rhythm but have not had one: Studies have shown that an ICD in certain people can lower the risk of death more than heart rhythm medicine can. ^{footnote 2} For example, in one study ICDs lowered the number of deaths from 9 out of 100 people to 4 out of 100. ^{footnote 3}

There are several risks to getting an ICD. But the risks are different for each person. The risk for problems associated with the implant procedure might be higher for people who are age 80 or older. The risks also depend on the type of ICD that you get.

During the procedure. If problems happen during the procedure, doctors likely can fix them right away.

• Serious bleeding could occur after placement of the ICD. This happens from 1 to 6 times out of 100. Serious bleeding doesn’t happen 94 to 99 times out of 100. ^{footnote 4}
• A lung could collapse (pneumothorax) from a buildup of air in the space between the lung and the chest wall. But a pneumothorax can be treated, and people recover well. This happens less than 1 time out of 100. This doesn’t happen 99 times out of 100. ^{footnote 4}
• In the hospital, serious problems, such as heart injury or stroke, happen less than 1 time out of 100. Serious problems don’t happen 99 times out of 100. ^{footnote 5}

After the procedure. Problems after the procedure can be minor, like mild pain, or serious, like an infection. But your doctor can solve most of these problems. And most people do not have long-term problems.

• You may have pain, bleeding, or bruising soon after the procedure.
• The leads that attach to the heart may break or stop working right. This can happen between 2 and 15 times out of 100 after 5 years of having the ICD. So it does not happen about 85 to 98 times out of 100. ^{footnote 6} But the risk of a lead breaking or not working right appears to increase over time. One long-term study found that, after 10 years, 20 out of 100 leads had problems. This also means that 80 out of 100 leads didn’t have problems. ^{footnote 7} If a lead does break or does not work anymore, you would need surgery. The surgery would be more complex than that needed to replace an ICD battery.
• You could get an infection where the ICD is placed. This happens about 1 to 2 times out of 100. So there is no infection about 98 to 99 times out of 100. ^{footnote 8}
• The ICD could shock the heart when it shouldn’t. There is no way to know if or when this could happen. It might never happen. In studies, these shocks happened to 3 to 21 out of 100 people over 1 to 5 years. This means that these shocks didn’t happen in 79 to 97 people out of 100. ^{footnote 5} Your doctor will program your ICD to lower the risk of one of these shocks.
• There also is a chance that a manufacturer may recall an ICD for a problem. If this were to happen, you might need surgery to take out the ICD and leads.

Daily precautions. You’ll need to take steps to safely use electric devices. 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 do not affect your ICD.

You will need regular monitoring and checkups with your doctor to make sure that the ICD is working well and that the programming is right for you.

It’s important to keep taking any medicines your doctor has prescribed. You’ll also need to follow a healthy lifestyle. This includes eating heart-healthy foods, getting regular exercise, and not smoking.

If the ICD gives you a lot of shocks, your doctor may prescribe the rhythm-control medicine amiodarone. This medicine helps prevent abnormal heart rhythms and may keep the ICD from sending shocks too often. Your doctor also could suggest catheter ablation to lower the number of times the ICD shocks you. Catheter ablation can lower the chance of some abnormal heart rhythms, such as atrial fibrillation or ventricular tachycardia. These rhythms can cause the ICD to shock you.

An ICD runs on a battery that lasts from 5 to 8 years. To have the battery replaced, you will need minor surgery.

Your doctor may advise you to get an ICD if you have had a dangerous abnormal heart rhythm or if you are at risk for having one. You and your doctor will decide whether an ICD is right for you.

Based on personal feelings, some people decide not to get an ICD. For example, they might worry a lot about getting a shock, they may not want to have the surgery to implant the ICD, or they don’t want to have a device inside of them.

Talk with your doctor about the possibility of turning off the ICD at the end of life. Many people consider turning off the ICD when their health goals change from living longer to getting the most comfort possible at the end of life. Turning off your ICD is legal. It isn’t considered suicide. The decision to leave on or turn off your ICD is a medical decision that you make based on your values.