An implantable cardioverter-defibrillator (ICD) is a device that detects any life-threatening, rapid heartbeat. This abnormal heartbeat is called an arrhythmia. If it occurs, the ICD quickly sends an electrical shock to the heart. The shock changes the rhythm back to normal. This is called defibrillation.
Alternative Names
ICD; Defibrillation
Description
An ICD is made of these parts:
- The pulse generator is about the size of a large pocket watch. It contains a battery and electrical circuits that read the electrical activity of your heart.
- The electrodes are wires, also called leads, that go through your veins to your heart. They connect your heart to the rest of the device. Your ICD may have 1, 2, or 3 electrodes.
- All ICDs have a built-in pacemaker. Your heart may need pacing if it is beating too slowly or too fast, or if you have had a shock from the ICD.

A cardiologist or surgeon most often will insert your ICD when you are awake. The area of your chest wall below your collarbone will be numbed with anesthesia, so you will not feel pain. The surgeon will make an incision (cut) through your skin and create space under your skin and muscle for the ICD generator. In most cases, this space is made near your left shoulder.
The surgeon will place the electrode into a vein, then into your heart. This is done using a special x-ray to see inside your chest. Then the surgeon will connect the electrodes to the pulse generator and pacemaker.
The procedure most often takes 2 to 3 hours.
Some people with this condition will have a special that combines a defibrillator and biventricular pacemaker placed. The pacemaker device helps the heart to beat in a more coordinated fashion.