What is an ICD?

An ICD (implantable cardioverter defibrillator) is an electronic device that constantly monitors your heart rhythm. When it detects a very fast, abnormal heart rhythm, it delivers energy to the heart muscle. This causes the heart to beat in a normal rhythm again.

Why is an ICD needed?

Ventricular tachycardia and ventricular fibrillation are two life-threatening heart rhythms that cause the heart to beat very fast. These conditions can be fatal if not treated immediately.

Your doctor has recommended that you receive an ICD because you have had at least one episode of these heart rhythms or are at high risk of developing these types of heart rhythms.

Who needs an ICD?

An ICD may be recommended for people who:

  • Had a prior episode of sudden cardiac arrest
  • Had a prior episode of ventricular fibrillation
  • Had at least one episode of ventricular tachycardia
  • Had a prior heart attack and have an increased risk for sudden cardiac arrest or sudden cardiac death
  • Have hypertrophic cardiomyopathy

Together, you and your doctor will determine if an ICD is the right treatment for you.

How does an ICD work?

The ICD monitors the heart rhythm, identifies abnormal heart rhythms and determines the appropriate therapy to return your heartbeat to a normal heart rhythm. Your doctor programs the ICD to include one or all of the following functions:

  • Anti-tachycardia pacing (ATP) – When your heart beats too fast, a series of small electrical impulses are delivered to the heart muscle to restore a normal heart rate and rhythm.
  • Cardioversion – A low energy shock is delivered at the same time as your heartbeat to restore a normal heart rhythm.
  • Defibrillation – When the heart is beating dangerously fast, a high-energy shock is delivered to the heart muscle to restore a normal rhythm.
  • Bradycardia pacing – When the heart beats too slow, small electrical impulses are sent to stimulate the heart muscle to maintain a suitable heart rate.

Types of ICDs

Is the ICD implant procedure safe?

A device implant is generally a very safe procedure. However, as with any invasive procedure, there are risks. Special precautions are taken to decrease your risks. Please discuss your specific concerns about the risks and benefits of the procedure with your doctor.

Where is the implant procedure performed?

In most cases, the implant procedure takes place in a special room in the Electrophysiology Lab. When the epicardial implant approach is used, the procedure takes place in a surgical suite.

This information is about testing and procedures and may include instructions specific to Cleveland Clinic.
Please consult your physician for information pertaining to your testing.

Reviewed: 05/15