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.

• 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