ICD; Defibrillation

An implantable cardioverter-defibrillator (ICD) is a device designed to quickly detect a life-threatening, rapid heartbeat coming from the bottom chamber of the heart. It tries to convert an abnormal rhythm back to normal by delivering an electrical shock to the heart. This action is called defibrillation.

An ICD can prevent sudden cardiac death.

An ICD is made of several parts:

• A pulse generator sends the powerful shock to the heart. It runs on batteries. The generator is implanted under the skin, usually on the upper left side of the chest.
• An electronic switchboard (circuit) tells the device when to "fire" the shock.
• Electrodes (wires) go through the veins of the heart and connect the heart to the rest of the device. The wires sense the heart beat and carry the shock to the heart muscle.

All ICDs have a built-in pacemaker. Pacing may be necessary to support the heart in some instances, for example, after a shock, or during a very slow heart beat. The pacemaker also allows the device to correct some rapid heartbeats by pacing even faster for a short period of time. Also, all of today's bi-ventricular pacemakers can work as an ICD.

Images

Normal heart rhythm

Heart, front view

Heart, section through the middle

Conduction system of the heart

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Implantable cardioverter Prevention

Review Date: 07/12/2006
Reviewed By: Glenn Gandelman, MD, MPH, Assistant Clinical Professor of Medicine, New York Medical College, Valhalla, NY. Review provided by VeriMed Healthcare Network.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)