What is the primary function of an implantable cardioverter-defibrillator (ICD)?

The primary function of an implantable cardioverter-defibrillator (ICD) is to monitor heart rhythms and deliver shocks for life-threatening arrhythmias. An ICD is specifically designed to detect abnormal heart rhythms, particularly those that can lead to sudden cardiac arrest, such as ventricular fibrillation and ventricular tachycardia. When the device detects these dangerous rhythms, it can deliver electrical shocks to restore a normal heart rhythm, effectively saving the patient’s life.

This life-saving capability is essential for individuals at high risk of cardiac arrest, especially those with a history of severe arrhythmias or heart failure. The ICD's ability to continuously monitor the heart's electrical activity and intervene when necessary is what sets it apart from other devices focused on improving heart function or supporting circulation. In contrast, treatments aimed at improving muscle strength or regulating temperature, or interventions focused solely on circulation, do not address the immediate need for rhythm correction that the ICD provides. Therefore, option C correctly describes the critical role of the ICD in managing life-threatening arrhythmias.