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Implantable cardioverter-defibrillators (ICD)
Treatment for the prevention of sudden death is one of the most active areas of investigation in hypertrophic cardiomyopathy. The original treatment to prevent sudden death is the use of antiarrhythmic medications, but recent research indicates that implantable cardioverter-defibrillators may be more effective.
ICDs are highly effective at interrupting potentially lethal heart rhythm disorders. Research in people with HCM has shown that those who have previously experienced a cardiac arrest are quite likely to experience another episode of similar heart rhythms. In these people, the likelihood of the ICD discharging to avert a potentially fatal heart rhythm is 10 percent per year. For other people who have not had cardiac arrest but who are at increased risk for sudden death due to other factors, the likelihood of their ICD interrupting a potentially fatal heart rhythm is about 4 percent to 5 percent per year.
Like cardiac pacemakers, ICDs are small devices that monitor the heart rhythms and send electrical impulses to the heart. If the heart rate becomes dangerously slow, the ICD responds exactly like a pacemaker, sending an electrical impulse that cannot be felt but stimulates the heart to beat. Unlike a pacemaker, ICDs also treat unstable and potentially lethal rhythms such as ventricular tachycardia (VT) and ventricular fibrillation (VF). When these rhythms occur, the ICD transmits a succession of low-energy impulses called pacing, or a high-energy shock, or a combination of the two. Usually described as feeling like a kick in the chest, these shocks may be painful, but last only a fraction of a second, with no lingering pain or damage.
The implantation procedure is done under general anesthesia and requires one to two days of hospitalization. After the anesthetic is administered, the surgeon will make an incision and place one or two electrical leads inside the heart. After the leads are tested, the ICD is implanted in a surgically-created pocket near the collarbone. In some instances, an additional lead may be placed under the skin near the rib cage. Usually there is some lingering pain in the area of the incision that can be managed with pain medication. When you are discharged, the hospital will provide a card that identifies you as having an ICD.
After the cardioverter defibrillator is implanted, patients can gradually return to an active lifestyle as recommended by their doctor. There may be some restrictions on driving a car or other vehicle, and a stress test may be necessary to ensure your safety and prevent any unintended shocks. Doctors can adjust the electrical programming of ICDs without additional surgery. In addition, you will need to keep a written diary of any electrical therapy given by the ICD--including when it happened, what you were doing, any symptoms experienced before the shock, and how your body responded.
General precautions for ICDs include:
- Avoid contact sports.
- Avoid medical procedures such as magnetic resonance imaging (MRI), lithotripsy (a procedure to remove kidney stones), and cautery (using heat or electricity to burn tissue).
- Tell the healthcare provider you have an ICD before receiving radiation therapy or diathermy (therapy that uses electricity to generate heat).
- Do not allow airport security personnel to use hand-held metal detectors on your body. Ask to be searched by hand.
- Avoid magnetic fields and keep strong magnets away from the ICD.
- Stay at least 8 feet away from arc welders.
- Show medical personnel the ICD card when receiving care.
Emotional support and encouragement from family members and friends are very important part of helping patients live with their heart condition and ICDs. Other ways family members can participate in the medical care:
- Complete a cardiopulmonary resuscitation (CPR) lifesaving course.
- Help maintain a diary and an ID bracelet or necklace with up-to-date medical information.
- Memorize the name of the ICD manufacturer.
- Be prepared to show medical personnel the ICD card when healthcare is being administered.
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