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Defibrillator

An automatic implantable defibrillator, AICD, is a device used to treat the life threatening heart rhythm disorders called ventricular tachycardia or ventricular fibrillation. Patients with these arrhythmias usually have some structural heart disease. Most commonly these people have coronary artery disease and a previous heart attack resulting in significant damage to the heart muscle. This predisposes the heart to develop electrical instability and deadly arrhythmias. Symptoms occur precipitously and include shortness of breath, dizziness, lightheadedness, loss of consciousness or a cardiac arrest.

Patients with this problem are evaluated extensively with an echocardiogram and a cardiac catheterization. An electrophysiology study is also usually done which is an invasive procedure to evaluate the heart's electrical system.

An ICD is a very sophisticated device which detects arrhythmias and terminates them either by pacing or delivering a shock. Previously, the patient's chest had to be opened to permit the application of patches and leads directly to the heart itself. However, the technology has advanced to the point where these devices are now implanted very much like a pacemaker. The patient is either put under general anesthesia or heavily sedated. An incision is made below the collarbone and a pocket formed. One or more leads are passed to the heart through a large vein under the collarbone. The leads are connected to the ICD generator which is placed into the pocket. The system is tested to insure that it functions appropriately. The entire procedure should last about an hour. Despite the fact that most patients who need these devices have very sick hearts, the procedure is relatively safe with a low risk. Potential complications include bleeding, infection or collapse of the lung. Prior to discharge from the hospital the device will be programmed appropriately.

An office visit will be scheduled about two weeks after surgery at which time the wound will be inspected and the ICD evaluated thoroughly. Periodic office visits will be required to ensure that the device is functioning normally and to assess battery life. The battery lasts from four to seven years and when it reaches the replacement indicator it must be replaced.

What restrictions are recommended depend on each patient's individual problem and underlying heart disease. In general, the implantation of a transvenous ICD is well tolerated and very effective in treating life threatening arrhythmias.