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Implantable Defibrillator Insertion

Implantable cardioverter defibrillatorAn implantable cardioverter defibrillator (ICD) is a small electronic device connected to the heart. It is used to continuously monitor and help regulate potentially fast and life-threatening electrical problems with the heart.

The ICD, about the size of a stopwatch, is implanted under the skin just below the collarbone. It consists of a pulse generator and wires, called leads. The pulse generator contains the battery and a tiny computer. One or more lead wires connect the pulse generator to specific locations in the heart.

The ICD responds to irregular life-threatening heart rhythms from the lower chambers of the heart with pacing that corrects a fast rhythm and promotes a normal heartbeat, or a shock (defibrillation) that resets the heart rhythm to prevent sudden cardiac arrest. An ICD also records and stores information about your heart rhythm and therapies delivered by the ICD for your doctor to review.

Most people are unaware when the ICD is pacing the heart. But, a defibrillation shock is described by many as feeling like a "kick in the chest."

The ICD can also be programmed to work as a basic pacemaker as needed. Sometimes after a shock is delivered, the heart may beat too slowly. The ICD has a "back-up" pacemaker, which can stimulate the heart to beat faster until the normal heart rhythm returns. The ICD can act as a pacemaker any time the heart rate drops below a preset rate.

Conditions Treated

You may need an ICD if you have survived sudden cardiac arrest due to ventricular fibrillation, have fainted due to ventricular arrhythmia or if you have certain inherited heart conditions.

An ICD is generally needed for those at high risk of cardiac arrest due to a ventricular arrhythmia. This includes people with heart failure who have problems with the contraction of the heart, such as abnormal left ventricular ejection fraction.

What to Expect

Having an ICD implanted may be done on an outpatient basis or as part of a hospital stay. The patient receives a sedative medication through an IV to help relax, but stays awake during the procedure. After a local anesthetic has been administered, the physician makes a small incision under the collarbone.

A sheath, or introducer, is put into a blood vessel. The ICD lead wire is threaded through the introducer into the blood vessel and advanced into the heart. Fluoroscopy, a special type of X-ray displayed on a TV monitor, is used to position the lead. The ICD generator is slipped under the skin through the incision after the lead wire is attached to the generator. The ICD is tested to ensure everything is working correctly, and the incision is closed.

Under the careful watch of their physician, the patient is able to return to a normal daily routine within a few days. After implantation, the ICD requires regular evaluation (called an interrogation) to evaluate its function and battery status, and to check for any significant events stored by the device. A home monitor may be provided that can communicate with the ICD wirelessly.

The patient is given specific instructions about what to do the first time the ICD delivers a shock, for example, dial 911 or go to the nearest emergency room.

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