What is the primary purpose of an implanted cardioverter-defibrillator (ICD) in heart failure patients?

• A. To terminate life-threatening ventricular arrhythmias and prevent sudden cardiac death
• B. To pace the heart during bradycardia only
• C. To monitor blood pressure continuously
• D. To deliver chronic antiarrhythmic drug therapy

Answer: (A)

An implanted cardioverter-defibrillator is placed to protect against sudden cardiac death by recognizing dangerous fast heart rhythms, mainly ventricular tachycardia and ventricular fibrillation, and delivering therapy to restore a normal rhythm. In heart failure patients, these life-threatening arrhythmias are a major cause of premature death, so the ICD’s primary job is to detect them and terminate them, often with a shock and sometimes with anti-tachycardia pacing to interrupt the tachycardia without a shock. It is not primarily a device for pacing during slow heart rates, it doesn’t monitor blood pressure, and it doesn’t deliver chronic drug therapy.