To track the patient's heart rate, implantable defibrillators—tiny, battery-operated devices—are positioned beneath the patient's chest or abdomen. When palpitations increase, the device notices this and restarts the heartbeat normally. In individuals who have chronic ventricular tachycardia or atrial fibrillation, these devices are essential for preventing sudden cardiac arrest. ICDs use electrodes to continuously monitor the heart rhythm and, if an abnormal rhythm is discovered, to give treatments.
