This
information courtesy of the National Institute of
Neurological Disorders and Stroke.
Carotid Endarterectomy
What
is a carotid endarterectomy?
A carotid endarterectomy is a surgical procedure in
which a doctor removes fatty deposits from one of the
carotid arteries, two main arteries in the neck supplying
blood to the brain. Carotid artery problems become more
common as people age. The disease process that causes
the buildup of fat and other material on the artery
walls is called atherosclerosis, popularly known as
"hardening of the arteries." The fatty deposit
is called plaque; -- the narrowing of the artery is
called stenosis. The degree of stenosis is usually expressed
as a percentage of the normal diameter of the opening.
Why is the surgery performed?
Carotid endarterectomies are performed to prevent stroke.
Two large clinical
trials supported by the National Institute of Neurological
Disorders and Stroke (NINDS) have identified specific
individuals for whom the surgery is highly beneficial
when performed by surgeons and in institutions that
can match the standards set in those studies. The surgery
has been found highly beneficial for persons who have
already had a stroke or experienced the warning signs
of a stroke and have a severe stenosis of 70 percent
to 99 percent. In this group, surgery reduces the estimated
2-year risk of stroke by more than 80 percent, from
greater than 1 in 4 to less than 1 in 10.
Surgery reduces the 5-year risk of stroke
by 6.5 percent for patients with 50 to 69 percent stenosis,
compared to an 80 percent risk reduction for patients
with greater than 70 percent stenosis. Patients with
50 percent stenosis or lower do not show enough benefit
from endartarectomy to outweigh the risks of the procedure.
With the completion of the NASCET trial, patients with
moderate stenosis will be better able to decide whether
to risk surgery in order to prevent possible future
strokes. The point at which surgery begins to confer
a significant benefit seems to be around the time that
the artery is 50 percent blocked.
In another trial, the procedure has also
been found highly beneficial for persons who are symptom-free
but have a severe stenosis of 60 percent to 99 percent.
In this group, the surgery reduces the estimated 5-year
risk of stroke by more than one-half, from about 1 in
10 to less than 1 in 20.
What is a stroke? A stroke occurs when blood flow is cut off
from the brain. In the same way that a person suffering
a loss of blood to the heart can be said to be having
a "heart attack," a person with a loss of
blood to the brain can be said to be having a "brain
attack." There are two kinds of stroke, hemorrhagic
and ischemic. Hemorrhagic strokes
are caused by bleeding within the brain. Ischemic strokes,
which are farmore common, are caused by a blockage of
blood flow in an artery in the head or neck leading
to thebrain. Some ischemic strokes are due to stenosis,
or narrowing of arteries due to the build up of plaque,
fatty deposits and blood clots along the artery wall.
A vascular disease that can cause stenosis is atherosclerosis,
in which deposits of plaque build-up along the inner
wall of large and medium-sized arteries, decreasing
blood flow. Atherosclerosis in the carotid arteries,
two large arteries in the neck that carry blood to the
brain, is a major risk factor for ischemic stroke.
What are the symptoms of a stroke?
Symptoms of stroke include:
Sudden numbness, weakness, or paralysis of face,
arm or leg, especially on one side of the body.
Sudden confusion, trouble talking or understanding
speech.
Sudden trouble seeing in one or both eyes.
Sudden trouble walking, loss of balance, or coordination.
Sudden severe headache with no known cause (often
described as the worst headache in a person?s life).
Symptoms may last a few moments and then
disapppear. When they disappear within 24 hours or less,
they are called a transient ischemic attacks (TIA).
How important is a blockage as
a cause of stroke? A blockage of a blood vessel is the most frequent
cause of stroke and is responsible for about 80 percent
of the approximately 700,000 strokes in the United States
each year. With nearly 150,000 stroke deaths each year,
stroke ranks as the third leading killer in the United
States after heart disease and cancer. Stroke is the
leading cause of adult disability in the United States
with 2 million of the 3 million Americans who have survived
a stroke sustaining some permanent disability. The overall
cost of stroke to the nation is $40 billion a year.
How many carotid endarterectomies
are performed each year? In 1995, the most recent year for which statistics
are available from the National Hospital Discharge Survey,
there were about 132,000 carotid endarterectomies performed
in the United States. The procedure has a 40-year history.
It was first described in the mid-1950s. It began to
be used increasingly as a stroke prevention measure
in the 1960s and 1970s. Its use peaked in the mid-1980s
when more than 100,000 operations were performed each
year. At that time, several authorities began to question
the trend and the risk-benefit ratio for some groups,
and the use of the procedure dropped precipitously.
The NINDS-supported North American Symptomatic Carotid
Endarterectomy Trial (NASCET) and the NINDS-supported
Asymptomatic Carotid Atherosclerosis Study (ACAS) were
launched in the mid-1980s to identify the specific groups
of people with carotid artery disease who would clearly
benefit from the procedure.
How much does a carotid endarterectomy
cost?
The total average cost for the diagnostic tests, surgical
procedure, hospitalization and followup care is about
$15,000.
What are the risk factors and
how risky is the surgery?
Important risk factors in addition to the degree of
stenosis include, gender, diabetes, the type of stroke
symptoms (whether in the brain or in the eye), blockage
of the carotid artery on the opposite side, and the
use of aspirin immediately prior to the surgery. Without
other complicating illnesses, age alone is not a worrisome
risk factor. Risk factors can affect patients in two
ways. They can, particularly in combination, greatly
increase a person?s risk of having a stroke. In addition,
these risk factors can increase the likelihood of surgical
complications.
How is carotid artery disease
diagnosed?
In most cases, the disease can be detected during a
normal checkup with a physician. Some of the tests a
physician can use or order include history and physical
exam, doppler ultrasound imaging, oculoplethysmography
(OPG), computed tomography (CT), arteriography and digital
subtraction angiography (DSA), magnetic resonance angiography
(MRA). Frequently these procedures are carried out in
a stepwise fashion: from a doctor's evaluation of signs
and symptoms to ultrasound, with arteriography, DSA
or MRA reserved for difficult diagnoses.
A doctor will ask about symptoms of a
stroke such as numbness or muscle weakness, speech or
vision difficulties, or lightheadedness. Using a stethoscope,
a doctor may hear a rushing sound, called a bruit (pronounced
"brew-ee"), in the carotid artery. Unfortunately,
dangerous levels of disease sometimes fail to make a
sound, and some blockages with a low risk can make a
sound.
Doppler
ultrasound imaging. This is a painless, noninvasive
test in which sound waves above the range of human hearing
are sent into the neck. Echoes bounce off the moving
blood and the tissue in the artery and can be formed
into an image. Ultrasound is fast, risk-free, relatively
inexpensive and painless. Unfortunately, there is a
small possibility of error in an ultrasound study. A
stenosis with a high level of risk will occasionally
be incorrectly reported as a low-risk finding. Conversely,
a stenosis with a low level of risk will sometimes be
reported as a high level of risk. In carefully calibrated
ultrasound laboratories, ultrasound studies can be up
to 95 percent accurate and offer visualization of the
anatomy, evaluation of the blood flow rate and turbulence,
and characterization of the plaque. Performing an ultrasound
study requires a great deal of skill which is not always
available.
Oculoplethysmography (OPG). This procedure
measures the pulsation of the arteries in the back of
the eye. It is used as an indirect check for blockages
in the carotid arteries.
Computed Tomography
(CT). This test produces a series of cross-sectional
X-rays of the head and brain. It cannot detect carotid
artery disease but may be ordered by a doctor to investigate
other possible causes of symptoms. The test is also
called a CAT scan, for computer assisted tomography.
Arteriography and Digital
Subtraction Angiography (DSA). Arteriography is
an X-ray of the carotid artery taken when a special
dye is injected into another artery in the leg or arm.
A burning sensation may be felt when the dye is injected.
DSA is also an X-ray study of the carotid artery. It
is similar to arteriography except that less dye is
used. A person having a DSA must remain still during
the test. These invasive procedures are more expensive
and carry their own small risk of causing a stroke.
Magnetic Resonance
Angiography (MRA). This is a very new imaging technique
that is more accurate than ultrasound yet avoids the
risks associated with X-rays and dye injection. An MRA
is a type of magnetic resonance image that uses special
software to create an image of the arteries in the brain.
A magnetic resonance image uses harmless but powerful
magnetic fields to create a highly detailed image of
the body's tissues.
What
is "best medical therapy" for stroke prevention?
The mainstay of stroke prevention is risk
factor management: smoking cessation, treatment
of high blood pressure and heart disease and control
of blood sugar levels among persons with diabetes. Additionally,
physicians may prescribe aspirin,
warfarin, or
ticlopidine.
Prepared
by the Office of Scientific and Health Reports of the
National Institute of Neurological Disorders and Stroke,
National Institutes of Health in January 1998.
Last reviewed: July 1, 2001
Additional Sites for More Information
About Carotid Endarterectomy:
The information contained in this
web site is not a substitute for medical advice or treatment.
Consultation with your doctor or health care professional is recommended.
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