What Are ICDs, and Do I Need One for Heart Failure?

Medically Reviewed by James Beckerman, MD, FACC on April 08, 2023

Your heart has a tough job: It’s responsible for pumping blood throughout your entire body. Most people hardly notice as their heart does its job all day, every day.

There are a few different kinds of irregular heartbeat, known as arrhythmias.

  • If your heart beats too fast, you might have a type of arrhythmia called ventricular tachycardia.
  • If your heart can’t pump enough blood because of an unsteady heartbeat, you might have ventricular fibrillation.

In either case, an ICD can sense and stop a dangerous, irregular heartbeat. It does this by sending an electrical shock to your heart back into a normal rhythm and beat.

An ICD will also help lower your chances of your heart actually stopping (cardiac arrest), which can be life threatening.

An ICD is different from a pacemaker. Both are devices your doctor implants under your skin to treat arrhythmias. But a pacemaker can usually only help your heart if it’s beating too slowly. An ICD is actually bigger, and has a pacemaker built into it.

Your heart rate and rhythm is controlled by electrical signals. When there’s a problem with this electrical system, it can cause a dangerous arrhythmia and your heart won’t be able to pump blood as it should.

Doctors sometimes have to use electrified paddles to “shock” the heart of a person who has gone into cardiac arrest. An ICD essentially does the same thing, but it’s automatic and inside your body.

Your ICD connects to your heart with wires and electrodes. It monitors your heartbeat, and if it detects an irregular rhythm, it can send one of several types of pulses.

Low-energy pacing therapy. These are minor and usually for slower ventricular tachycardia. They’re also typically painless, or may feel like fluttering in your chest.

Cardioversion therapy. These high-energy pulses are for faster ventricular tachycardia. They may feel like someone is kicking your chest.

Defibrillation therapy. The strongest kind of shocks are for very serious rhythm problems with your heart. If your ICD begins defibrillation therapy, you may feel severe pain in your chest.

Your ICD can usually restore your normal heartbeat with just one shock. Sometimes you might get two or more shocks in a 24-hour period. You should get emergency medical care if this ever happens.

You’ll need minor surgery to have an ICD implanted under your skin. It takes just a few hours. Most people who get ICDs are awake during the procedure. In these cases, the surgeon will use a numbing medication and a sedative to make you feel relaxed. Sometimes, you will get general anesthesia and not be awake.

During the procedure, your doctor will use X-ray images to guide wires into your veins and connect them to your heart. The other ends of the wires are attached to the ICD, which is placed under your skin, usually below your collarbone.

Your doctor will then program the ICD for your specific arrhythmia.

Once your ICD is in and working, you’ll likely have to stay in the hospital for a few days so your doctor can keep testing before you go home. Your incision might be sore, but your doctor may prescribe pain medication to help you feel more comfortable.

You also won’t be able to drive for at least a week after your procedure, so make sure you have a ride home from the hospital. You’ll need a few weeks to recover at home, too. Your doctor will give you specific instructions, but you’ll probably have to avoid certain exercises and sports for at least a month. 

It rarely happens, but certain things can interfere with your ICD, so you need to be aware. Be cautious around the following:

Cell phones. They’re safe to use, but keep yours away from your chest so your ICD doesn’t mistake the cell signal for your heartbeat.

Power generators. Stay at least 2 feet away from power generators, welding equipment, high-voltage transformers or motor-generator systems.

Medical equipment. You might not be able to have some procedures, such as MRIs, MRAs, and radiofrequency or microwave ablation.

Magnets. Keep them at least 6 inches from your ICD site because they can interfere with your ICD.

Metal detectors. You’ll get a card after surgery that says you have an ICD. Show it to airport security when you travel. But be aware that hand-held metal detectors also have magnets that can mess with your ICD. Be sure that if you’re scanned with one on your ICD site, it doesn’t last more than 30 seconds.

Your ICD contains a battery that can last up to 7 years, and your doctor will check it during regular appointments two to four times a year. You’ll need to have a minor procedure to replace the battery when it is almost out of power.

Show Sources


National Heart, Lung, and Blood Institute: “What Is an Implantable Cardioverter Defibrillator?”

Mayo Clinic: “Implantable cardioverter-defibrillators (ICDs)”

University of Iowa Hospitals & Clinics: “Pacemakers and Defibrillators: Frequently Asked Questions”

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