What is an Implantable Cardioverter Defibrillator (ICD)?
An ICD is a battery-powered device placed under the skin that monitors your heart rhythm. If an abnormal heart rhythm is detected the device will deliver an electric shock to restore a normal heartbeat if your heart is beating in a dangerous rhythm.
ICDs have been very useful in preventing sudden death in patients with known, sustained ventricular tachycardia or fibrillation. Studies have shown that they may 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 or abdomen, 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?
It knows when the heartbeat is not normal and tries to return the heartbeat to normal.
- If your ICD has a pacemaker feature 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 gives defibrillation shocks to stop the abnormal rhythm.
- It works 24 hours a day.
New devices also provide “overdrive” pacing to electrically convert a sustained ventricular tachycardia (fast heart rhythm) and "backup" pacing if bradycardia (slow heart rhythm) occurs. They also offer a host of other sophisticated functions such as storage of detected arrhythmic events and the ability to perform electrophysiologic testing. Stored information can help your doctor optimize the ICD for your needs.