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Implantable Cardioverter
Defibrillator (ICD)
Definition:
An ICD is an electronic
device that constantly monitors your heart rate and rhythm. When it detects
a very fast, abnormal heart rhythm, it delivers energy to the heart muscle.
This causes the heart to beat in a normal rhythm again.
The ICD
The ICD has two parts:
the leads and a pulse generator
Lead(s)
monitors the heart rhythm, delivers energy used for pacing, cardioversion
and/or defibrillation. |
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Generator
houses the battery and a tiny computer. Energy is stored in the battery
until it is needed. The computer receives information from the leads
to determine what rhythm is occurring. |
There are different
types of ICDs:
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Single chamber
ICD
A lead is attached in the right ventricle. If needed, energy is delivered
to the ventricle to help it contract normally |
Dual chamber
ICD
Leads are attached in the right atrium & the right ventricle.
Energy is delivered first to the right atrium and then to the right
ventricle, helping your heart to beat in a normal sequence |
Biventricular
ICD
Leads are attached in the right atrium, the right ventricle and the
left ventricle. This technique helps the heart beat in a more balanced
way and is specifically used for patients with heart failure. |
How an ICD works
The ICD is an amazing
little computer. It monitors the heart rhythm, identifies abnormal heart
rhythms, and determines the appropriate therapy to return your heartbeat
to a normal heart rhythm. Your doctor programs the ICD to include one
or all of the following functions:
- Anti-tachycardia
Pacing (ATP) When the heart beats too fast, a series of small
electrical impulses are delivered to the heart muscle to restore a normal
heart rate and rhythm.
- Cardioversion
A low energy shock is delivered at the same time as your heartbeat
to restore a normal heart rhythm.
- Defibrillation
When the heart is beating dangerously fast, a high-energy shock is
delivered to the heart muscle to restore a normal rhythm.
- Bradycardia
pacing When the heart beats too slow, small electrical impulses
are sent to stimulate the heart muscle to maintain a suitable heart
rate.
Why you need an ICD
ICDs are used for:
- people
who have had an episode of sudden cardiac death or ventricular fibrillation
- people
who have had a heart attack and are at high risk for sudden cardiac
death
- people
who have hypertrophic cardiomyopathy and are at high risk
- people
with at least one episode of ventricular tachycardia
To prepare for an
ICD:
- ask your doctor
what medications you are allowed to take. Your doctor may ask you to
stop certain medications one to five days before your test (such as
aspirin products). If you are diabetic, ask your doctor how you should
adjust your diabetic medications.
- do not eat or drink
anything after midnight the evening before your test. If you must take
medications, drink only with a sip of water.
- when you come to
the hospital, wear comfortable clothes. You will change into a hospital
gown for the procedure. Leave all jewelry or valuables at home.
What to expect:
- You will lie on
a bed and the nurse will start an intravenous line (IV) into your arm
or hand. This is so you may receive medications and fluids during the
procedure. You will be given an antibiotic to prevent infection and
a medication through your IV to relax you and make you drowsy, but it
will not put you to sleep.
- The nurse will
connect you to several monitors. The monitors allow the doctor and nurse
to check your heart rhythm, blood pressure and other measurements during
the pacemaker implant.
- Your left or right
side of your body, from your neck to your groin will be shaved and cleansed
with a special soap. Sterile drapes are used to cover you from your
neck to your feet. A strap will be placed across your waist and arms
to prevent your hands from coming in contact with the sterile field.
The
ICD may be implanted in two ways:
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Endocardial
(transvenous) approach most common
- A
small incision is made under the collar bone
- Lead
is placed into a vein and guided inside your heart
chamber
-
generator is placed under skin in upper chest
and attached to the lead(s).
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On rare occasion,
it may be necessary for your doctor to implant your ICD by epicardial
approach (outside your heart). this requires open heart surgery. Instead
of placing the lead through a vein and guiding it to the heart, it is
sewn onto the heart. Your doctor will decide if this approach is necessary
for you.
The ICD implant takes
about two to five hours to perform.
After the procedure:
- Hospital stay:
you will be admitted to the hospital for about one to three days. The
nurses will monitor your heart rate and rhythm. The length of your hospital
stay depends on the type of ICD procedure you had. The morning after
your implant, you will have an EKG, blood tests and a chest x-ray to
ensure the leads and/or patches and ICD is in the proper position. You
will also go to the electrophysiology lab to have your ICD checked.
This will involve testing the ICD and programming it to your needs.
- Activity:
you may move your arm normally. You
can do most activities when you return home.
- Avoid lifting
objects that weigh more than 20 pounds or pushing or pulling heavy
objects.
- If you had
heart surgery, it may take longer to get back to some activities.
- Your doctor
or nurse will discuss specific activities with you before you leave
the hospital.
- Electrical
interference: most electrical devices, such as microwave ovens,
do not interfere with ICD function. You
need
to avoid strong electric or magnetic fields such as:
- Some industrial
equipment, high output ham radios, high intensity radiowaves (found
near large electrical generators, power plants or radiofrequency transmission
towers), and arc or resistance welders
Stay
at arms length away from
less powerful electric or magnetic fields such as:
- Large magnets,
stereo speakers, airport security wands, antennas used in ham or CB
radios.
- Cellular phones
should kept at least 6 inches from your ICD and not on the same side
as your ICD.
Do
not undergo any tests that require magnetic resonance imaging (MRI).
You may have CT ("CAT") scans done if necessary
If
you have concerns about your job or activities, ask your doctor.
- ICD therapy:
You may or may not be aware of when your ICD detects and corrects your
heart rhythm. Often it depends on the type of therapy you receive:
- Pacing
you may or may not feel the impulses usually they are not detectable
- Cardioversion
shock feels like a thump on the chest; discomfort does not linger
- Defibrillation
you may be unconscious (passed out) and not feel the shock. If you
are awake, the shock feels like a kick in the chest; felt for only
a moment.
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If
you receive a shock:
- Stay
calm. Sit or lie down.
- Ask
someone to stay with you.
- If
you do not feel well after the shock, call your doctor or an
ambulance (Dial 911 in most areas).
- If
you feel fine after the shock, you do not need to seek immediate
medical attention. Call your doctor within 24 hours.
If someone
is touching you when the ICD fires, they may feel a tingling feeling.
This is not harmful to them.
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- Follow-up:
Regular follow-up is important after an ICD implant. Your doctor will
tell you how often you will need to have the ICD checked. During ICD
checks, the doctor will determine if the ICD had detected or treated
any abnormal heart rhythms and will check the ICD battery. These visits
are very important. You will also need to see a cardiologist at least
once a year.
Click here to:
.Resource: Heart Center, What you need to know about your
ICD, Cleveland Clinic Foundation, Cleveland, OH (2001)
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