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Implantable Cardioverter-Defibrillator (ICD)

An implantable cardioverter-defibrillator (ICD) is a small device that uses electrical pulses or shocks to help control abnormal heart rhythms, especially ones that can be life-threatening. An ICD is also known as an automatic implantable cardioverter-defibrillator (AICD).

An ICD is implanted under the skin in the chest. A wire threaded through a large vein connects the device to the 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 to get it back to normal. 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. If your heart is beating too slowly, the ICD acts as a pacemaker, sending mild electrical pulses to bring your heart rate back up to normal.

Last Revised: June 2, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Rakesh K. Pai, MD, FACC

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