Who needs an implantable cardioverter defibrillator?

Implantable cardioverter defibrillators (ICDs) are used in children, adolescents, and adults. Your doctor may recommend an ICD if you're at risk for certain types of arrhythmia.

ICDs are used to treat life-threatening ventricular arrhythmias, such as those that cause the ventricles to beat too fast or quiver. You may be considered at high risk for a ventricular arrhythmia if you:

• Have had a ventricular arrhythmia before
• Have had a heart attack that has damaged your heart's electrical system

ICDs often are recommended for people who have survived sudden cardiac arrest (SCA). People who have certain heart conditions that put them at high risk for SCA also may need ICDs.

For example, some people who have long QT syndrome, Brugada syndrome, or congenital Cardiac, Other Heart and Vascular Diseases may benefit from an ICD, even if they've never had ventricular arrhythmias before.

Some people who have heart failure may need a CRT-D device. This device combines a type of pacemaker called a cardiac resynchronization therapy (CRT) device with a defibrillator. CRT-D devices help both ventricles work together. This allows them to do a better job of pumping blood out of the heart.

This answer from the National Heart, Lung and Blood Institute has been reviewed and/or edited by Dr. William D. Knopf.

An implantable cardioverter-defibrillator is recommended for people who are at high risk for cardiac arrest. In most instances, people who have had prior heart damage as a result of heart attacks or “cardiomyopathy,” typically an inherited heart muscle disease, are at high risk for cardiac arrest. People at high risk have a poorly contracting heart muscle.

Also, there are some people with a normally contracting heart who have inherited instability of the heart rhythm. This includes “long QT syndrome” and similar conditions.

The defibrillator acts as a protective “parachute” that corrects dangerous heart rhythm disorders with an electrical shock. Recent news stories to the contrary, most defibrillators placed by heart rhythm specialists are appropriate to protect high-risk patients, who succeed admirably.