Implantable cardioverter-defibrillators: Controlling a chaotic heart

Cardiac arrest — the sudden failure of the heart to pump blood — claims about 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 that causes the ventricle to quiver ineffectively, unable to supply blood to your body

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

Tests that help determine if an ICD is for you

To determine whether you need an ICD, your doctor may perform any of these diagnostic tests:

• 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 during 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 to 48 hours.
• Event recorder, a pager-sized device that records your heart activity. Unlike a Holter monitor, it doesn't operate continuously and you turn it on only when you feel your heart is beating abnormally.

What is ICD surgery like?

Implanted cardioverter-defibrillator on an X-ray.

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The surgery to implant an ICD is usually relatively minor. It can be performed with local anesthesia and a sedative that puts you in a relaxed state but allows you to remain aware of your surroundings.

The procedure typically takes one to three hours. Testing the ICD requires shocking your heart and for that, general anesthesia is used. You stay in the hospital one or two days, and the ICD may be evaluated one more time before you're discharged. Any additional studies are usually performed through the device via radio waves and are nonsurgical.

After surgery you may have some pain in the incision area, which can remain swollen and tender for a few days or weeks. Pain medication often is prescribed, and you can take nonaspirin pain relievers as the severity lessens. Unless your doctor instructs you to, don't take pain medication containing aspirin because it may increase the risk of bleeding.

Related

Implantable cardioverter-defibrillator: After your ICD is implanted
Pacemakers: Generating regular heartbeats