Automatic Implantable Cardioverter Defibrillators (AICD)
Why is the doctor performing this procedure?
To monitor an abnormally beating heart, either one that beats too fast (Tachycardia), too slow (Brachycardia) or irregularly (Atrial Fibrillation). These abnormal heart beats are referred to as arrhythmias.
What is an AICD?
An AICD is a device that monitors a person's heart rate. They are generally implanted into heart failure patients. The device is programmed to perform the following tasks: speed up or slow down your heart, depending upon the heart rate. The AICD gives your heart a shock if you start having life threatening arrhythmias or an abnormally high heart rate. Arrhythmias occur when your heart does not beat normally. Some arrhythmias can cause the heart to completely stop beating. The shock given by the AICD can make the heart start beating normally again. An AICD can also make your heart beat faster if your heart is not beating fast enough.
There are different kinds of AICDs, but they all have 2 parts: electrodes (thin flexible wires) and a generator. The electrodes or "leads" sense or watch the heart's electrical activity. The generator is the battery power source and the "brains" of the AICD. It is a small metal can about the size of a deck of cards. The generator stores information about any arrhythmias you have. The generator also keeps track of how often it needs to give your heart a shock. Some AICDs also function as pacemakers for heart rates that are too slow or too fast.
When is an AICD indicated?
Your doctor has recommended you for an AICD system for one or more of the following reasons:
What happens during implantation of an AICD?
- At least one episode of Ventricular Tachycardia (VT) or Ventricular Fibrillation (Vfib)
- Previous cardiac arrest or abnormal heart rhythm that has caused you to pass out
- A fast heart rhythm that keeps returning and could cause death
- A fast heart rhythm that cannot be cured by surgery
- A fast heart rhythm that cannot be controlled with medications
- Severe side effects from medications
Prior to implantation of an AICD, an Electrophysiological study (EP study) may be performed. An EP study is used to help decide whether to use an AICD or whether to use drugs for treatment.
The newer AICD units can be implanted without major surgery. The procedure is performed under local anesthesia, but sometimes it is done under general anesthesia. You will be hooked up to an intravenous (IV) line and will receive sedation. Before the doctor makes an incision, your upper chest will be cleaned and your torso draped. Your arms may be loosely strapped to prevent movement during the testing of the AICD.
The doctor will make an incision in your upper chest area below the collarbone. A wire will be inserted through a vein into your heart. Sometimes more than one wire is used. The doctor will create a "pocket" in your chest, where the AICD is inserted. The AICD is connected to the wires. The doctor will test the AICD by creating an arrhythmia and then observing whether the AICD delivers the required therapy. Later that day, or the next day, your AICD system will be checked and tested again with a computer called a "programmer." This procedure is called "noninvasive programmed stimulation" or "pre-discharge testing." You will receive sedation. The doctor will provoke an arrhythmia to see if the device works. The AICD will deliver a shock (defibrillation). The staff will fine-tune the equipment.
Recovery time after implantation of newer AICD units is quite short. Hospital stays are rarely longer than 3 or 4 days and there is quick return to prior activity levels. People with AICDs must continue to follow their doctor's recommendations regarding medication, diet, and exercise.
Prior to discharge, you will be shown how to examine your incision site. You should look for signs of infection each day such as increased redness, increased tenderness, swelling around the incision, drainage from the incision. You should also report a fever over 100°F that lasts longer than 24 hours. You will also receive instructions on your AICD.
Do AICD batteries wear out?
The AICD pulse generator runs on a battery. The battery provides the energy needed to monitor your heart rhythm, pace the heart or deliver electrical therapy. Just like a battery you use with your electronic equipment, the battery can wear down over time. How long the AICD pulse generator will last is dependent on what settings are programmed into the system. It is also affected by how much therapy you receive.
Your doctor will open the pocket of skin where the pulse generator is located to replace your AICD pulse generator. The old pulse generator will be unplugged from the leads. The leads are checked to make sure they are still working properly. Then they are connected to the new AICD pulse generator. A test is preformed to make sure the new system is working properly.
Once the doctor knows the AICD is working properly, he/she will stitch the pocket of skin closed. The entire procedure takes about an hour. It is considered a minor operation, and you should be able to return to normal activities soon.
What is Echocardiography?
An Echocardiogram is a noninvasive, risk-free test that uses ultrasound waves to assess cardiac structure and mobility, particularly of the valves. During the test, a small transducer is held against the chest. The transducer sends ultrasound waves that bounce off parts of the heart. A computer uses the information coming from the transducer to make an image of the heart. The image is displayed on a monitor, and it can be recorded on videotape or printed on paper.
The Echocardiogram usually combines three different techniques. The M-mode echo produces an image that looks more like a tracing than a heart. The M-mode echo helps measure the size of the heart chambers.
The two-dimensional (2-D) echo shows the actual shape and motion of the different heart structures. The images represent "slices" of the heart in motion.
The Doppler echo allows doctors to assess the flow of blood through the heart. You may hear a swooshing or pulsating sound with this test. This is not the actual sound of your heart, but an amplified computerized audio signal.
How do I prepare for the procedure?
There is no special preparation for Echocardiography. You may eat and go about your normal activities, unless you are told otherwise. Make sure you wear a two-piece outfit because you will be instructed to undress from the waist up and wear a hospital gown.
What happens during the procedure?
You will lie on a hospital stretcher. Electrodes (small sticky patches) are placed on the chest and shoulders to monitor the heartbeat. You will need to lie quietly during the test on your left side with your head elevated slightly. An odorless water-soluble gel is applied to the chest. An Echo Tech moves the transducer over the chest to obtain different views of your heart. You may be asked to change positions and to exhale or hold your breath for a few seconds. The images are recorded on videotape and printed on paper. The Echo Tech is not authorized to give you your results. The doctor will either be present during the test, or you may be able to get the results before you leave. Otherwise, your doctor will discuss the results with you during an office visit.
Why is the Echo done?
The Echocardiogram gives doctors information about the heart, such as:
Where is the test performed?
- Size of the heart - The echo is used for measuring the size of the heart chambers and thickness of the heart muscle.
- Pumping strength - The test shows whether the heart is pumping at full strength or is weakened. It can also help determine whether the various parts of the heart pump equally.
- Valve problems - The echo shows the shape and motion of the heart valves. It can help determine if a valve is narrowed or leaking and shows how severe the valve problem is.
- Other uses>- The echo may be used to detect the presence of fluid around the heart, blood clots, or masses inside the heart, and abnormal holes between heart chambers. Sometimes, the echo is combined with an exercise or dobutamine stress test to see how well the heart pumps when it is accelerated.
Generally done in the Non-Invasive Cardiology Testing Center
How long does this test take?
The test is painless and takes 20 to 45 minutes to complete.