More Than ‘Fancy Pacemakers’ — How ICDs Will Help You
When you’re at risk of sudden cardiac death, a small device — the implantable cardioverter-defibrillator, or ICD — can save your life. Discover how an ICD works, who needs one, and when.
When you’re at risk of sudden cardiac death, one small device can save your life. That’s the implantable cardioverter-defibrillator (ICD).
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
The pacemaker delivers 60, 80 or 100 imperceptible, low-energy electrical impulses per minute to keep a slow heart beating normally. The ICD delivers high-energy electrical impulses only during life-threatening arrhythmias to shock the heart back into normal rhythm.
The ICD — about twice as big as the tablespoon-sized pacemaker — is similarly implanted under the skin near your shoulder and connected to the heart by wires called leads.
When the heart’s pumping chambers, or ventricles, start beating too fast (tachycardia) or quivering (fibrillation), the heart can’t pump much blood. “You pass out within five to 10 seconds, and if you’re not rescued with an automated external defibrillator (AED) within 10 minutes, the brain dies,” says Dr. Wilkoff.
Ninety-five percent of cardiac arrest episodes are fatal because:
But once a defibrillator is implanted in your heart, your odds of survival jump to 98 or 99 percent. That’s because when an episode occurs, the ICD automatically delivers a shock to restart your heart within seconds.
Anyone at increased risk of sudden cardiac arrest is a candidate for an ICD. Having a low ejection fraction puts you at increased risk.
The ejection fraction — the amount of blood your heart pumps out with each beat — should be 50 to 60 percent. Certain conditions can lower your ejection fraction to 35 percent or less, such as a heart attack (myocardial infarction), or heart muscle disease (cardiomyopathy).
“Heart failure symptoms develop when the ejection fraction is low, usually with shortness of breath, swelling in the legs and abdomen, and fatigue on exertion,” says Dr. Wilkoff.
You can develop the need for an ICD with a cardiomyopathy, or have a heart attack, at any age. “You may need one in your 20s, but usually not until you’re in your 40s, 50s, 60s or 70s,” he says.
Your doctor will measure your ejection fraction with an echocardiogram and will also need an electrocardiogram (EKG). He or she will monitor your heart rhythm to see if it’s fast or slow and determine whether you need an ICD.
“You may not have your first episode of cardiac arrest until age 25, but the next episode may happen soon thereafter or not for another 10 years,” says Dr. Wilkoff. “Your risk increases over time, and if we wait for an event to occur, you may not survive.”
One of the biggest gains with the ICD: You’ll no longer have to worry about being alone when an arrhythmia occurs.
“Most of the time, you forget about the ICD. You can play active sports, golf, fly — do just about anything,” says Dr. Wilkoff. “Our monitoring is sophisticated, and we follow patients very carefully. If a problem should arise, we’ll know it before you do.”
Data from the ICD can be sent to the monitoring team from anywhere in the world, over the internet or by telephone.