What is an implantable cardioverter-defibrillator (ICD)?

Dr. Kushal K. Handa, MD
Cardiologist (Heart Specialist)

An implantable cardioverter defibrillator (ICD) is a device that is implanted in the chest to monitor for and, if necessary, correct episodes of an abnormal heart rhythm (arrhythmia) by pacing or shocking the heart.

Implantable cardioverter defibrillators (ICDs) are used to protect against life-threatening arrhythmias and the sudden cardiac death that can result. ICDs are utilized in patients who have already had these types of arrhythmias and in those who are at risk for developing them. ICDs are small devices, similar to pacemakers, implanted under the skin, most often in the chest. ICDs continuously monitor the heartbeat and immediately sense abnormally rapid and potentially dangerous heart rhythms. ICDs then deliver electrical impulses to terminate the arrhythmias and allow the normal heartbeat to resume.

ICDs have many additional functions, ensuring that they provide the appropriate life-saving therapy when needed and allowing physicians to obtain and review important information about the heart rhythm and to alter therapy when appropriate.

You’ve probably viewed this scene many times on television or in movies: a patient who is in sudden cardiac arrest is wheeled into an emergency room and paddles are applied to his or her chest, delivering an electrical shock that restarts the heart’s rhythm. The paddles are a form of external defibrillator. For patients who are at high risk of experiencing a life-threatening, abnormal heart rhythm (arrhythmia), a small, implantable defibrillator may be placed in the chest or abdomen. The electrical device monitors for abnormal and dangerous heart rhythms and can shock the heart back to a normal rhythm if a life-threatening arrhythmia develops.

An implantable cardioverter-defibrillator (ICD) is a device a doctor implants to read and treat lethal cardiac arrhythmias.

Intermountain Registered Dietitians
Nutrition & Dietetics Specialist

An ICD (implantable cardioverter defibrillator) is a small device that corrects your heart rhythm. An ICD has a pulse generator that is implanted in your body, and one or more leads (wires) that are threaded into your heart

In an ICD, the leads “listen” to your heartbeat and send information to the pulse generator. If there’s a problem with your heart rhythm, the generator creates an electrical pulse and sends it through the leads to your heart.

An ICD is basically a pacemaker with an added function. While a pacemaker corrects a heartbeat that is too slow, an ICD also corrects a heartbeat that is too fast.

Dr. Douglas E. Severance, MD
Family Practitioner

An implantable cardioverter-defibrillator (ICD) is a small battery-powered electrical impulse generator which is implanted in patients who are at risk of sudden cardiac death due to ventricular fibrillation and ventricular tachycardia. The ICD runs on batteries and is surgically implanted on the left side of your collarbone. Electrode-tipped wires go from the ICD through your veins and into your heart. The ICD then monitors your heart rhythm continuously, 24 hours a day. The ICD acts as a pacemaker if your heart rhythm gets too slow. If you have ventricular tachycardia or ventricular fibrillation, the ICD emits an electrical shock to convert the heart to normal rhythm.

An implantable cardioverter defibrillator, or ICD, is a small battery-operated medical device that is implanted into the heart and programmed to recognize potentially dangerous types of arrhythmias and correct them with a shock. ICDs have been shown to effectively terminate 95% of deadly ventricular arrhythmias.

Some patients with heart failure have dangerously fast heartbeats called "ventricular tachycardia" or "ventricular fibrillation." This fast heartbeat can cause serious symptoms such as fainting or even death. An Implantable Cardioverter Defibrillator (ICD) is like a pacemaker that can be inserted under your skin. It can recognize a dangerous heartbeat and send an electrical signal to the heart and return the heart back to a normal heartbeat.

Dr. Imran A. Niazi, MD
Cardiac Electrophysiologist

An implantable converter defibrillator is a battery-powered device slightly larger than a matchbox that is implanted under the skin just below the collar bone. It is used to correct and regulate the heart rhythm, and some types are used to help improve heart function.

The implantable converter defibrillator, or ICD, has a computer chip that continuously records your heart rhythm and looks for abnormalities. If the heartbeat slows too much or stops, the defibrillator acts like a pacemaker and speeds up the heartbeat to a normal rhythm. If the heartbeat goes dangerously fast (which can be fatal), the defibrillator corrects the rhythm by giving a series of electrical pulses or by giving an electrical shock to the heart. Some defibrillators (called biventricular ICDs) are very helpful in making the heart chambers work in unison. This can improve heart function considerably.

An implantable cardiac defibrillator is a device about the size of a pager that monitors your heart and delivers an electrical shock to correct tachycardia (heart beating too fast). Many defibrillators can also function as pacemakers to treat bradycardia (heart beating too slow) by delivering a weaker electric shock.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.