An implantable cardioverter-defibrillator (ICD) — a pager-sized device which is implanted in your chest — may reduce your risk of dying if your heart goes into a dangerous rhythm and stops beating (cardiac arrest). You may need an implantable cardioverter-defibrillator if you have a dangerously fast heartbeat (ventricular tachycardia) or a chaotic heartbeat that makes it so your heart can’t supply enough blood to the rest of your body (ventricular fibrillation).
Implantable cardioverter-defibrillators work by detecting and stopping dangerous, abnormal heartbeats (arrhythmias). An implantable cardioverter-defibrillator continuously monitors your heartbeat and delivers electrical shocks to restore a normal heart rhythm when necessary.