Implantable Cardioverter Defibrillator (ICD)

What is an Implantable Cardioverter Defibrillator (ICD)?             
An ICD is a battery-powered device placed under the skin that keeps track of your heart rate. Thin wires connect the ICD to your heart. If an abnormal heart rhythm is detected the device will deliver an electric shock to restore a normal heartbeat if your heart is beating chaotically and much too fast.

ICDs have been very useful in preventing sudden death in patients with known, sustained ventricular tachycardia or fibrillation. Studies have shown that they have a role in preventing cardiac arrest in high-risk patients who haven't had, but are at risk for, life-threatening ventricular arrhythmias.

Why do I need an ICD?
Your doctor may recommend an ICD if you are at risk of a life-threatening ventricular arrhythmia because of having:

  • Had a ventricular arrhythmia
  • Had a heart attack
  • Survived a sudden cardiac arrest
  • Long QT Syndrome
  • Brugada syndrome
  • A congenital heart disease or other underlying conditions for sudden cardiac arrest

How is an ICD implanted?
A battery-powered pulse generator is implanted in a pouch under the skin of the chest, often just below the collarbone. The generator is about the size of a pocket watch. Wires or leads run from the pulse generator to positions on the surface of or inside the heart and can be installed through blood vessels, eliminating the need for open-chest surgery.

How does an ICD work?
An ICD knows when the heartbeat is not normal and tries to return the heartbeat to normal.

  • ICD’s have pacemaker capability and when your heartbeat is too slow, it works as a pacemaker and sends tiny electric signals to your heart.
  • When your heartbeat is too fast or chaotic, it can provide defibrillation shocks to stop the abnormal rhythm.
  • ICD’s will provide “overdrive” pacing to electrically convert a sustained ventricular tachycardia (fast heart rhythm) and "backup" pacing if bradycardia (slow heart rhythm) occurs. ICD's  also offer a host of other sophisticated functions such as storage of detected arrhythmic events and the ability to perform electrophysiology testing. Stored information can help your doctor optimize the ICD for your needs.

Will an Implantable Cardioverter Defibrillator Affect My Lifestyle?

Devices That Can Disrupt Implantable Cardioverter Defibrillator Functions

Once you have an ICD, you have to avoid close or prolonged contact with devices that have strong magnetic fields. Devices that can interfere with an ICD include:

  • High-tension wires
  • Metal detectors
  • Industrial welders
  • Electrical generators

These devices can disrupt the electrical signaling of your ICD and prevent it from working well. You may not be able to tell whether your ICD has been affected.

How likely a device is to disrupt your ICD depends on how long you're exposed to it and how close it is to your ICD.

Cell Phone Usage

To be on the safe side, some experts recommend not putting your cell phone in a shirt pocket over your ICD (if they're turned on). You may want to hold your cell phone up to the ear that's opposite the site where your ICD was implanted.

MP3 Player 

If you strap your MP3 player to your arm while listening to it, put it on the arm that's farther from your ICD.


You can walk through security system metal detectors at your normal pace. You can safely be checked  with a metal detector wand as long as it isn't held for too long over your ICD site. You should avoid sitting or standing close to a security system metal detector. Notify airport screeners if you have an ICD.

Procedures That Can Disrupt Implantable Cardioverter Defibrillator Functions

Some medical procedures can disrupt your ICD. These procedures include:

  • Magnetic resonance imaging (MRI)  MRI compatible ICD's are available, please ask your doctor or device representative if your device is compatible. 
  • Shock-wave lithotripsy to treat kidney stones
  • Electrocauterization to stop bleeding during surgery

It is important to notify all of your doctors, dentists, and medical technicians that you have an ICD.

Medical Card

The device company will provide you with  a card that states what kind of ICD you have. Carry this card in your wallet. You might want to wear a medical ID bracelet or necklace that states that you have an ICD.

Physical Activity

An ICD usually won't limit you from taking part in sports and exercise, including strenuous activities.

You may need to avoid full-contact sports, such as football. Such contact could damage your ICD . Ask your doctor how much and what kinds of physical activity are safe for you.

Follow Up Care

Your doctor will want to check your ICD regularly.

To check your ICD, you will be monitored through the Cardiac Device Clinic.  You will be provided a monitor to check your device remotely(from home) on a quarterly basis however you will also be asked to visit the office at least once a year.

When do I call the doctor?

The high-energy pulses or shocks your ICD gives last only a fraction of a second. They may feel like thumping or a painful kick in the chest, depending on their strength.

You should call the doctor if you receive a shock from your device.  If you receive multiple shocks you should call 911 and go to the nearest emergency room. 

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