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 irregular (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:
- 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
What happens during implantation of
an AICD?
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 anaesthesia, but
sometimes it is done under general anaesthesia. 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 "non-invasive
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.
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