What it is
An implantable cardioverter-defibrillator (ICD) is implanted the same way as a pacemaker and looks similar, but it's solving a different problem. A pacemaker corrects a heart that beats too slowly. An ICD watches for a dangerously fast, chaotic rhythm from the heart's lower chambers — one that, left alone, can be life-threatening within minutes — and delivers a shock to restore a normal rhythm if it detects one. Many ICDs also include standard pacemaker function for slow rhythms.
Who typically needs one
We generally consider an ICD for people who've already survived a dangerous arrhythmia, or who carry a meaningfully elevated risk of one — often tied to a prior heart attack, significantly weakened heart muscle, or an inherited rhythm condition. It's an individualized decision, weighing the specific risk against what it actually means to live with the device day to day.
Living with one
Most people with an ICD never get shocked, and the device just works quietly in the background. If you do get shocked, follow up with your care team promptly — both to confirm the device did what it was supposed to and to see whether anything about your treatment plan should change. Devices get checked periodically, remotely or in person, the same as a pacemaker.