Table of Contents
Definition of Implantable Cardioverter Defibrillator (ICD)
Implantable cardioverter defibrillator (ICD) is a small, battery-operated electronic device, similar to a pacemaker, that monitors the heart’s electrical activity for certain patterns of arrhythmia and administers a moderate electrical shock when the heart stays in the pattern beyond the programmed length of time. One or two wires, called leads, extend from the ICD’s pulse generator to the interior of the heart, threaded through a blood vessel during a procedure similar to a cardiac catheterization.
The cardiologist creates a small pocket in the tissues near the shoulder or in the abdomen to implant the pulse generator, a tiny computer. Once placed, the leads and the ICD are permanent. The cardiologist then programs the ICD to maintain the appropriate heart rhythm.
ICD is a treatment option for ventricular tachycardia and ventricular fibrillation, arrhythmia disorders that affect the ability of the ventricles to contract to expel blood from the heart. Ventricular tachycardia, in which the ventricles contract rapidly but regularly, is exhausting for the heart and does not generate adequate cardiac output to meet the body’s needs.
Ventricular fibrillation, in which the ventricles contract rapidly and irregularly, is life-threatening. An ICD can initiate pacing impulses when the heart’s rate becomes too slow or a stronger electrical impulse to shock the heart from a harmful to a normal rhythm (cardioversion). Most people do not feel the pacing impulses though do feel a jolt with cardioversion impulses. People who have ICDs need to be cautious around electrical devices because they generate magnetic fields that can interfere with an ICD’s operation and programming.
Page last reviewed: