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Implanted defibrillators can often stem ventricular arrhythmias with low-energy shocks. Sometimes, however, high-energy shocks are needed. These shocks, though short-lasting, can be painful--somewhat akin to a kick in the chest. The generators in implanted defibrillators usually last three to five years and can be replaced with a surgical procedure that usually requires only local anesthesia. The electrode leads tend to last longer, although they can develop cracks or component failures that require their replacement. A recent study of heart attack survivors by
Arthur Moss and colleagues from the University of Rochester (N.Y.) Medical
Center found implantable defibrillators cut survivors' risk of death in half. Normal Heart Rhythms Ventricular Fibrillation (VF) "Ventricular fibrillation" (VF) is similar to ventricular tachycardia. Instead of one abnormal impulse, many different impulses from the ventricles try to signal the heart to beat. The heartbeat is much faster-sometimes over 300 beats a minute-and very little blood is pumped from the heart to the brain and body. A person with VF becomes unconscious very quickly and may not remember anything that happened just before or during the episode. Electrical energy is used to try to "shock" the heart back to a more normal rhythm. If an episode of ventricular tachycardia or ventricular fibrillation continues without treatment, the heart cannot supply enough oxygenated blood to the brain and body tissues. Without oxygenated blood, the brain and body tissues cannot survive. What Is an AICD? What Does It Do? The AICD is an implantable electronic device designed to monitor your heart rhythm and determine if the rhythm is abnormal and needs correction. This monitoring of your heart rhythm is similar to the monitoring done by machines in the coronary care unit. If the AICD senses that the rhythm is ventricular tachycardia or ventricular fibrillation, it will deliver an "internal" shock to the heart to correct the abnormal rhythm. If you are awake, you may find this shock uncomfortable for a short time-similar to a hard thump on the chest. You may not feel the shock at all if you have nearly passed out. However, you may have an uncomfortable feeling in your chest as you wake up. If the first shock does not stop the abnormal rhythm, the AICD can give three to four additional shocks. After the abnormal rhythm stops, the AICD will reset itself automatically and prepare to shock again if the abnormal rhythm reappears. As long as your heart rhythm remains "normal," the AICD wire monitor your heart rhythm and wait until a shock is needed. What Does the AICD Look Like? How Does It Work The AICD includes a pulse generator and leads. The Pulse generator is about the size and shape of a deck of cards and weighs about 1/2 pound. The pulse generate implanted in your abdomen just underneath the skin. It made of a special kind of metal that normally does not react to body tissue. The pulse generator is connected one or more leads that are placed in and near your heart The lead system sends electrical signals from your heart the pulse generator, which continuously monitors your heart rhythm. When the pulse generator receives signals from the lead system that your heart rhythm is ventricle tachycardia or ventricular fibrillation, it will send a shock through the lead system to your heart to stop the abnormal rhythm. How Is the AICD Implanted? The AICD implant involves an operation to place the Lead or leads in and near your heart. Your doctors will make the decision about what kind of surgery to use based on: ˇYour size and body shape If you have already had chest surgery What kind of lead or leads will be used What the safest type of surgery will be for you If you are having open-heart surgery, the lead or leads and pulse generator may be implanted during your heart operation. The types of operations differ in the locations of the incisions made into your chest. Below are brief descriptions of various implant operations. Your doctors will choose the operation that is best for you. Thoracotomy: The main incision will be made between your ribs on your left side. A second small incision may be made near your collarbone. This operation is usually chosen for a person who has already had chest surgery and may have scar tissue around the heart. Sternotomy: The main incision will be made lengthwise over your breastbone, which will be divided so the doctor may look directly at your heart. Your doctor may also decide to make a small incision near your collarbone. Subxiphoid: The main incision will be made lengthwise below and slightly to the left of your breastbone. Another small incision may be made near the base of your neck or 3 your collarbone. Open-Heart: Your doctor will decide on the incision for this type of operation depending on the other kind of surgery you need. This type of operation is done for your heart problems, and the AICD will be implanted as additional help for your heart problems. Transvenous Insertion: A small incision will be made near your collarbone. The lead will be threaded into the heart through a vein. The tip of the lead is then positioned inside the heart. Subcutaneous or Submuscular Placement: This procedure may be done in addition to one of the above. A small incision will be made on your left chest wall and a lead placed just underneath your skin or muscle layers.
No matter which type of operation your
doctor chooses, the pulse generator will be implanted in the same location.
Usually, one or two leads are inserted through a large vein inside your chest
and into the right chamber of your heart. Another lead may be placed over the
lower left chamber on the outside of your heart where your heart comes to a
point (the "apex" of your heart). Alternative leads may be placed on
the surface of your heart if your doctor thinks that they will work better for
you. The end of the lead or leads that connect to the pulse generator are then
brought down underneath the skin to your abdomen, below the waistline, and
connected to the pulse generator. When the connections are completed, a
"pocket" will be formed just underneath your skin layers. (This
"pocket" is similar to the kind made for implanted pacemakers.) The
pulse generator is then placed in the "pocket." After you've had your AICD implanted and are back in a regular hospital room, you will be asked to return to your usual activities as soon as your doctors and nurses feel that you are rested enough. It is important that you become actively involved in your own care after surgery so you may return to your normal activities more quickly. You may be asked to wear a special kind of tape recorder that records your heart rhythm while you perform your usual activities. (You may have worn this type of recorder before your surgery.) The results of these new recordings will be compared to those taken before your surgery. You may begin taking medications for your heart rhythm if your doctor thinks you should do so. A nurse or doctor will look at your incisions. After six or seven days, any external stitches will be removed. If you notice any of the following , ask your nurse or doctor to look at your incision again: 1. Oozing on or around your bandage, 2- Soreness around any of your incisions or around 3- Fluid leaking around the stitches of your incisions, 4- Swollen, red, or hot areas around your incisions five more days after your operation These things may not mean something is wrong, but it's best to let your doctor or nurse know to prevent any problems from developing. After you regain your strength, your doctor may ask you to have another EP test to further evaluate your AICD's function. This may be performed while you are awake, but you may be given some medication to make you feel calm during the test. Another test that may be performed after you regain your strength is an exercise treadmill test. These tests will help your doctor observe your heart rhythm and know how the AICD is functioning. When the tests are completed and the stitches removed, you may be allowed to go home. Don't forget any medicines you are supposed to take! Make sure you know what they are for and when to take them. What Should I Do After I Get Home? Then you first get home from the hospital, you will probably tire easily. You should increase your activity slowly so you don't become too tired. A short walk a few times a day will help you become gradually stronger. Your doctor will help you decide what activities you may begin and how soon you may go back to work. After you've been home a few days, you should make an appointment to see your heart doctor. You should have your AICD tested every two months, or follow the schedule that your physician prescribes for you. The testing can be done in a doctor's office, emergency room, or clinic and usually takes a short time. Generally, the test will be performed by the same doctor who recommended that you receive the AICD. If you are taking special medications for abnormal rhythm you may need to Having a Follow-up Test Performed When you have your AICD pulse generator checked, The doctor or an assistant will use another device. This device works "noninvasively"-that is, it works from outside the body and is painless, and no surgery is needed. Using information from the testing device, your doctor ca tell how well the AICD is working. Sometimes it may be necessary to test the AICD two or three times to make sure the test readings are correct. The test should not hurt you. While the test is being performed the pulse generator discharges. However, the shock stays inside the pulse generator instead of going to your heart. I the test makes you feel uncomfortable, tell the doctor or a assistant what you are feeling. If you have any signs of ventricular tachycardia or fibrillation (fainting, nausea, weakness, rapid pulse rate, blackouts or problems with your medications, be What Should I Do If I Get a Shock At some time, you may experience an abnormal heart arrhythmia at home or elsewhere. If the abnormal rhythm does not stop b itself the AICD will shock your heart During the shock, an electrical voltage is present on the skin over your chest and back that someone touching you may feel. Let family members and persons caring for you know about this voltage so they will not be surprised if they happen to feel it. If you have any questions about the shock or the skin voltage, discuss them with your doctor. If you get an AICD shock, you or the people helping you should call your doctor's office to report the shock. If ambulance attendants or paramedics come to help you, you or someone who knows you should tell them about your AICD. Also, they should be shown your Identification Card and your Medic Alert* Identification. It is important to report all AICD shocks. It is possible that you could receive a shock without any symptoms of ventricular tachycardia or fibrillation. These shocks should also be reported to your doctor as soon as possible. It is important that your doctor or the doctors and nurses at your nearby hospital know about the AICD shock and your abnormal heart rhythm. They may want to examine you to make sure the symptoms of the abnormal heart rhythm have gone away and nothing else is causing difficulty. It is also possible that you may have symptoms of abnormal heart rhythm and not receive a shock from your AICD. For example, this could occur if the heart rhythm is too slow for the AICD to recognize. Symptoms of abnormal rhythm should always be reported to your doctors or nurses as soon as possible. Why Should I Carry My ID Card? You will receive a wallet-sized Identification Card containing information about the doctor to be called in case of an emergency. You should carry this ID card in your wallet where it can be easily seen. If you become unconscious, the people helping you will need to know about your AICD and whom they should contact, The card provides this important information. Also, if you go to a doctor or hospital for tests or problems other than your heart condition, always remember to report them about your AICD and show them your ID card! This information When Will My AICD Pulse Generator Have to Be Replaced? How Will This Be Done? The exact period for which the AICD will last depends Ton the number of shocks you receive. Please refer to your AICD warranty for the warranty period and for terms and conditions regarding device replacement. If you receive many AICD shocks or if you have a significant change in your heart rhythm or medication, you may need a replacement sooner. You will need to have surgery to remove the old pulse generator and have a new one implanted. In most cases, you will not need to have your lead or leads changed at the same time. The surgery involves making a new incision over the old scar on your abdomen and removing the pulse generator from its "pocket." The old pulse generator is disconnected and a new one is connected in its place. Your doctor will probably wish to test the new pulse generator before putting in the stitches. What Things Should I Avoid Doing? When you are feeling stronger and have returned To your usual activities, you should avoid: Any activity that involves rough contact with your pulse generator or lead system. Strong magnetic fields close to your pulse generator. This may make the AICD act as though it is being "tested," or may actually turn it off and prevent it from working when needed. If you hear beeping sounds coming from your pulse generator, move away from the area where you are standing. Call your doctor as soon as possible, explain exactly what happened, and follow his instructions. Do not place magnets on or near your pulse generator! Treatments or surgery involving the use of diathermy or electrocautery machines. Ask your doctor to consult CPI before using these machines in your care. Lifting heavy objects until your doctor says you can. Things I Should Do Always follow your doctor's instructions exactly. Always take medications prescribed for you as instructed by your doctor. Always call your doctor if you have questions, problems, or notice anything unusual. Always tell doctors and dentists treating you that you have an AICD. To Remember that rescue crews and family members may use other standard emergency measures such as cardiopulmonary resuscitation (CPR) and external defibrillation. Tell others to begin these measures if you should become unconscious. Keep ambulance and/or paramedic numbers close to the telephone for emergencies. To Consider teaching local emergency room and ambulance service staff about your device, how it works, and whom to call in an emergency.
Remember to Call Your Doctor If: Any of your incisions from surgery become reddened, You have a fever that will not go away after a few days At any time you have signs of your abnormal heart You plan to take a trip or move to another place You hear beeping tones coming from the pulse You have questions concerning your AICD You notice anything unusual or unexpected, especially You need to have any surgery during which equipment
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