An implantable cardioverter-defibrillator (ICD) — a pager-sized device — is placed in your chest to reduce your risk of dying if the lower chambers of your heart (ventricles) go into a dangerous rhythm and stop beating effectively (cardiac arrest). You might need an ICD if you have a dangerously fast heartbeat (ventricular tachycardia) or a chaotic heartbeat that keeps your heart from supplying enough blood to the rest of your body (ventricular fibrillation).
ICDs detect and stop abnormal heartbeats (arrhythmias). The device continuously monitors your heartbeat and delivers electrical pulses to restore a normal heart rhythm when necessary. An ICD differs from a pacemaker — another implantable device used to help control abnormal heart rhythms. An ICD is surgically placed under your skin, usually below your left collarbone. One or more flexible, insulated wires (leads) run from the ICD through your veins to your heart. Because the ICD constantly monitors for abnormal heart rhythms and instantly tries to correct them, it helps treat cardiac arrest, even when you are far from the nearest hospital. When you have a rapid heartbeat, the wires from your heart to the device transmit signals to the ICD, which sends electrical pulses to regulate your heartbeat.
Depending on the problem with your heartbeat, your ICD could be programmed for the following therapies: Low-energy pacing therapy- You may feel nothing or a painless fluttering in your chest when your ICD responds to mild disruptions in your heartbeat. Cardioversion therapy- A higher energy shock is delivered for a more serious heart rhythm problem. It may feel as if you’re being thumped in the chest. Defibrillation therapy- This is the strongest form of electrical therapy used to restore a normal heartbeat. During this therapy, most people become disoriented, dizzy or may pass out due to the life threatening arrhythmia that triggers the shock.
However, if the patient is fully awake during the shock, it may feel as if you’re being kicked in the chest, and it might knock you off your feet. The pain from this therapy usually lasts only a second. There should be no discomfort after the shock ends. Risks associated with ICD implantation are uncommon but may include: Infection at the implant site, Allergic reaction to the medications used during the procedure, Swelling, bleeding or bruising where your ICD was implanted, clot formation in or damage to the vein where your ICD leads are placed, Bleeding around your heart, which can be life-threatening, Blood leaking through the heart valve where the ICD lead is placed, Collapsed lung (pneumothorax).