The Implantable Cardioverter Defibrillator (ICD) is a small, lightweight electronic device that is placed inside your body. It keeps track of your heart rhythm. When you have an arrhythmia, the ICD helps your heart return to its normal rhythm. This rhythm is set by signals from the heart's electrical system. A problem with these signals can cause your heart to beat too quickly, too slowly, or irregularly. This is called an arrhythmia.
Some symptoms of a fast heart rhythm may include:
- Palpitations, (a fluttering, fast heartbeat), dizziness or lightheadedness
- Fainting spells
- Warm, flushed feeling
A heart rhythm problem can stop the heart from pumping blood. This is called cardiac arrest and can be life threatening. (Note: Cardiac Arrest is not the same as a heart attack. A heart attack is when a blood vessel to the heart muscle is blocked.)
You may be given an ICD if you have had a cardiac arrest or if you have a fast heart rhythm problem that could lead to cardiac arrest. The ICD is not a cure for your heart rhythm problem. It can save your life by quickly bringing a dangerously fast heart rhythm under control. You will need an ICD for the rest of your life, so having one implanted means a lifelong commitment.
Problems with electrical signals can cause very fast heart rhythms. Two common types of heart rhythms are Ventricular Tachycardia (V-Tach) and Ventricular Fibrillation (V-Fib). Both can lead to cardiac arrest, so an ICD is usually needed.
With ventricular tachycardia, a ventricle contains a group of abnormal electrical cells called a circuit. The circuit sometimes sends out signals that make the lower chambers beat very fast. The chamber don't have time to fill with blood before the next beat, so the heart pumps less blood than the body needs, causing your symptoms. V-Tach can progress to a more serious arrhythmia called ventricular fibrillation.
With ventricular fibrillation, abnormal circuits in the ventricles sometimes send signals quickly and irregularly. The heartbeat can be so fast and uneven that the heart muscle quivers rather than pumps. A quivering heart is in cardiac arrest. Emergency treatment must be given to get the heart pumping again, or death may result.
V-Tach and V-Fib usually develop in damaged heart muscle. This damage may be caused by:
- A scar on the heart muscle from a heart attack
- Cardiomyopathy, which is a diseased, weakened heart muscle
- Other problems, including heart valve problems and congenital (present at birth) heart problems
Sometimes a heart rhythm problem can exist even though the heart muscle hasn't been damaged. This is called a primary electrical problem. An Implantable Cardioverter Defibrillator (ICD) can help.
An ICD can do one or more of the following:
- Antitachycardia pacing (ATP): The ICD can send out a series of pulses to override a fast rhythm. This may feel like fluttering in your chest, or may not be felt at all.
- Cardioversion: If ATP doesn't slow a fast rhythm, the ICD can give the heart one ore more small shocks. These break up the fast rhythm. They may feel like thumps in your chest.
- Defibrillation: If the ICD senses a very fast, irregular rhythm, it quickly sends a strong shock to the heart to override the fast rhythm. You may feel this as a strong kick in your chest.
- Bradycardia Pacing: An ICD's main job is to slow a fast heart rhythm. At rare times, your heart may beat to slowly. This may happen if you have a second heart rhythm problem that causes a slow heartbeat. Your heart may also beat too slowly after an ICD shock. Most ICDs can send out pulses to get a slow heartbeat back to the right speed.
Inserting the ICD into your body is called implantation. ICD implantation is not open heart surgery. Rather, it's a minor procedure that's done in an operating room or cardiac catheterization lab. You'll be given instructions on how to prepare for the procedure.
The ICD can be inserted near the right or left shoulder. If you prefer to have it implanted on a particular side, discuss your preference with your physician.
Before the procedure begins, you may be given some medication to help you relax. This medication will help you "sleep" through part or all of the procedure, so you won't feel pain. The skin where the pacemaker is to be implanted will be washed and shaved. An incision is made in your skin below your collarbone. For an abdominal implant, a second incision is also made below your ribcage. A small "pocket" (space) is made under your skin or muscle for the ICD generator to sit in. For the abdominal implant, the pocket is made near the incision below the rib cage.
The lead for the ICD is threaded through the incision into a vein in your upper chest. The lead is then guided into your heart's chambers using x-ray monitors. Electrical measurements are taken to determine a good position for the lead in the heart. For an abdominal implant, the other end of the lead is threaded under the skin from the chest to the abdomen.
The ICD generator is attached to the lead. Then, the generator is placed in the pocket under your skin. The ICD's settings are programmed to treat your heart rhythm problem. The incision is then closed and covered with a sterile dressing. (Note: A patch electrode is sometimes also used to help the ICD do its job. If one is needed, your physician will make another incision to place the patch under the skin or muscle near your heart. A lead connects the patch to the generator.)
In rare cases, the ICD may be implanted through open chest surgery. This may be done along with open chest surgery for another heart problem, or if problems keep the leads from being placed in the veins. The chest is opened and the leads are attached to the outside of the heart. The generator is placed in a pocket in the abdomen.
After your ICD is implanted, you'll probably stay in the hospital for a day or two. Before you go home, you will be told how to take care of your incision site or sites as they heal. You may have some tests. You'll also have some follow-up visits scheduled.
During your stay in the hospital, your heart's signals are monitored to be sure the ICD is working right. Before you go home, an x-ray of your chest may be taken and the ICD settings may also be rechecked. This is done from outside your body.
To be sure your ICD is performing correctly, you will probably need to visit your physician or clinic several times a year. During these visits, the ICD's record is checked and the ICD's settings can be changed, if necessary. The settings can be changed from outside your body, without the need for surgery. You may still feel symptoms when you have a fast heart rhythm, but your ICD will stop them. If you do feel symptoms, follow your physician's advice on what to do next. Tests such as an ECG may be performed. Your ICD's battery will also be checked. ICD batteries last 3 to 7 years. Your physician will know well in advance when the battery needs to be replaced. The battery won't run down unexpectedly.
When you have an event, you may feel your usual symptoms of a fast heart rhythm. If you do, find a place to sit or lie down. Put your feet up. If possible have someone stay with you for about 15 minutes. You won't always feel the ICD working. Low-energy pulses may be enough to slow your heart rhythm. If a shock is needed, though, you will feel it. It may feel as light as a thump or as strong as a kick to the chest. Whether you feel it working or not, you can rely on your ICD to treat you when you need it. Very rarely, a person with an ICD may need additional medical care. Know what to do if this happens.
An ICD won't keep you from living an active life. You can usually do almost everything you did before you got your ICD, and since you will probably feel better, you may do even more!
When you first get your ICD, you'll be given an ID card to carry. This ID card contains important information about your ICD. It also tells others what to do in an emergency. Show it to any physician, dentist, or other medical professional you visit. Also, because pacemakers tend to set off security devices like those found in airports and libraries, you may need to show your card to security personnel.
ICD's are well protected from outside signals, so there are very few things that can interfere with your pacemaker. But if you ever feel symptoms that make you think a device is disrupting your ICD's signals, turn the device off or move away from it. Your symptoms should stop and your ICD shouldn't be damaged. To be safe, check with your physician.
Appliances which should be safe to use include:
- Microwave ovens and other appliances in good repair
- Hair Dryers
- Power Tools
- TV's and Radios
- Electric Blankets and Heating Pads
- Vacuum Cleaners
There are a few things to avoid that might interfere with your ICD. These include very strong magnets, (like those used for an MRI or in hand-held security wands), radio transmitting tours, ham radios, certain surgical instruments and cellular phones. When using a cellular phone, hold it on the ear farthest away from your pacemaker. Don't carry it in your breast pocket, even when it's turned off. Also, a running car engine generates an electrical field, so avoid leaning directly over the open hood of a running car.
With an ICD, you'll know that your heart rhythm problem can be managed. Now you can live your life to the fullest. Talk to your physician about exercise and ask whether there are any activities you should avoid.