Context

Cardiac arrest—the sudden failure of the heart to pump blood—claims approximately 335,000 lives each year in the United States, according to the American Heart Association. The most common heart-rhythm disorders (arrhythmias) that lead to cardiac arrest are:

  • Ventricular Tachycardia—a dangerously fast heartbeat
  • Ventricular Fibrillation—a rapid and chaotic heartbeat (causing the ventricle to quiver and pump ineffectively) that is unable to supply blood to your body

What is ICD Defibrillation?

An implantable cardioverter-defibrillator (ICD)—a pager-sized device implanted in your chest like a pacemaker—continuously monitors your heartbeat and delivers precisely calibrated electrical shocks to restore a normal heart rhythm. An ICD may reduce your risk of dying of cardiac arrest by detecting and stopping these dangerous arrhythmias in a quick and effective manner.

How do ICDs work?

You may have seen TV shows in which a hospital worker or paramedic ‘shocks’ an unconscious person out of cardiac arrest with a pair of electrified paddles. An ICD does the same thing, but it’s housed inside the body and the charge happens automatically when an arrhythmia occurs. It can save a person’s life by pacing the heart out of a dangerous arrhythmia.

This small, battery-powered device is surgically placed under the skin, usually below the left collarbone. One or two flexible, insulated wires (leads) run from the ICD through the veins and into the lower chambers of the heart.

Because the ICD is constantly on-guard for abnormal heart rhythms and instantly attempts to correct them, it can help to treat and prevent cardiac arrest, even if you’re hours away from a hospital.

Who needs an ICD?

You’re a prime candidate for an ICD if you’ve had ventricular tachycardia, survived a cardiac arrest or fainted from a ventricular arrhythmia. You may also benefit from an ICD if you have:

  • A history of coronary artery disease and prior heart attack that has led to a weak heart
  • A heart condition that involves abnormal heart muscle (such as enlarged (dilated cardiomyopathy) or thickened (hypertrophy cardiomyopathy) heart muscle)
  • An inherited heart defect that adversely affects your heart’s electrical system (including long QT syndrome, which can cause ventricular fibrillation and death even in young, active people with no signs or symptoms or heart problems; and other rare conditions including Brugada syndrome and arrhythmogenic right ventricular dysplasia)

Is an ICD right for me?

To determine whether you need an ICD, your doctor may perform diagnostic tests, including:

  • Electrocardiography (ECG)—a noninvasive test that measures your heart’s electrical activity
  • Echocardiography—a noninvasive ultrasound test that shows how well your heart pumps blood
  • Electrophysiology Study (EPS)—a procedure in which electrodes are guided through blood vessels to your heart, and used to test the function of your heart’s electrical system, locate short circuits, and identify your potential for heart-rhythm problems
  • Holter Monitoring—a noninvasive test that requires you to wear a device that records your heart’s electrical activity for 24 – 48 hours
  • Event Recorder—a pager-sized device that records your heart’s activity (Unlike a Holter monitor, it doesn’t operate continuously, and you turn it on only when you feel your heart is beating abnormally.)