An implantable cardioverter defibrillator, or ICD, is used to treat a dangerously fast heart rhythm. It’s a small, round disk that fits in the palm of your hand. It will be placed under your skin below the collarbone, or under your skin on the left side of your rib cage. Your pacemaker will have a couple small wires, call leads, that will be threaded through the veins from the ICD to your heart. The leads send electrical messages between the defibrillator and your heart.
The defibrillator will monitor your heart rhythm. When your heart starts to beat too fast, called ventricular tachycardia or ventricular fibrillation, the defibrillator will respond by sending a pulse to your heart to normalize its rhythm.