Tests and Procedures

Implantable cardioverter-defibrillators (ICDs)

Overview

An implantable cardioverter-defibrillator (ICD) is a small battery-powered device placed in your chest to detect and stop abnormal heartbeats (arrhythmias). An ICD continuously monitors your heartbeat and delivers electric shocks, when needed, to restore a normal heart rhythm.

You might need an ICD if you have a dangerously fast heartbeat that keeps your heart from supplying enough blood to the rest of your body (such as ventricular tachycardia or ventricular fibrillation) or if you are at high risk of such a heart rhythm problem (arrhythmia), usually because of a weak heart muscle.

An ICD differs from a pacemaker — an implantable device that can prevent dangerously slow heartbeats.

Types

An ICD is a type of cardiac therapy device. There are two basic types:

  • A traditional ICD is implanted in your chest, and the wires (leads) attach to your heart. The implant procedure requires invasive surgery.
  • A subcutaneous ICD (S-ICD) is another option that's implanted under the skin at the side of the chest below the armpit. It's attached to an electrode that runs along your breastbone. An S-ICD is larger than a traditional ICD but doesn't attach to your heart.