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What are the carotid arteries?
Two carotid arteries (one on each side of the neck) supply most of the blood to the brain. The carotid arteries can easily be felt on
each side of the neck immediately below the angle of the jaw. There are two smaller
arteries, the vertebral arteries, which run through the spine and supply blood
to the back part of
the brain (the brainstem and cerebellum). The carotid arteries supply the much larger
front part of the brain, where thinking, speech, personality and sensory and motor
functions reside.
How do the carotid arteries become diseased?
As people age, the carotid arteries develop atherosclerosis in the same manner
as the coronary arteries in the heart. Atherosclerosis is the buildup of cholesterol and
other material inside the inner lining of the arteries. These deposits lead to the
formation of plaques, which protrude from the inner lining of the arteries and obstruct
blood flow to organs such as the brain and heart.
The risk factors that have been linked to the development of atherosclerosis include:
- Smoking
- High cholesterol
- Hypertension
- Family history of atherosclerosis
Typically, the carotid arteries become diseased a few years after the coronary
arteries. People who have heart disease have a higher likelihood of having carotid disease
and people who have carotid disease have a higher likelihood of having heart disease.
What are the consequences of carotid artery disease?
As the carotid arteries narrow, the blood flow to the brain diminishes. If the
artery becomes completely blocked or if a piece of the plaque breaks loose and travels up
to the smaller arteries in the brain and blocks them, a stroke can result.
A stroke or "brain attack" is similar to a heart attack. A stroke occurs when
brain cells (neurons) are deprived of the oxygen and glucose carried to them by blood.
Oxygen and glucose are essential for neurons to function and survive. If the lack of blood
flow lasts for more than 3 to 6 hours, the damage is generally permanent. Strokes can
occur due to other causes such as rapid contractions of the upper heart chambers (atrial
fibrillation), severe weakening of the heart muscle (cardiomyopathy), or blockage of the
tiny arteries inside the brain.
What are the warning signs of stroke?
Some people will have a transient ischemic stroke (TIA) before they have a
full-blown stroke. TIA symptoms can include sudden loss of vision in one or both eyes,
weakness and/or numbness of one side of the body, slurring of speech or inability to
speak, or loss of coordination. A TIA is a medical emergency since it is impossible to
predict which TIAs will progress into a major stroke. Anyone having symptoms suggestive of
a stroke should be taken to the nearest emergency room.
What can be done to diagnose carotid disease before a stroke
happens?
Strokes are much easier to prevent than they are to treat, therefore, it is
crucial that people who are at risk for atherosclerosis have regular evaluations with
their primary care physician. Simply listening to the neck with a stethoscope will detect
about half of carotid blockages. A carotid ultrasound is a simple, non-invasive test to
accurately detect carotid blockages and can be performed at most offices and hospitals.
When should carotid artery disease be treated?
The decision to proceed with surgical therapy has to be made on an individual
basis by the patient and his or her physician. There is very strong evidence that patients
with 70 percent or greater narrowing who have had TIAs or a stroke and patients with 80
percent or
greater narrowing who are asymptomatic (ie, who don't have obvious symptoms) will benefit from surgery. Patients with as little
as 50 percent narrowing may benefit in certain cases.
What are the treatment options for carotid artery disease?
All patients with carotid artery disease should take aspirin. The standard
surgical treatment for carotid artery narrowing is carotid endarterectomy. In this
procedure, an incision is made in the neck and the inner, diseased layers of the artery
are cut out and the outer layer is sewn back together, allowing increased blood flow to
the brain. Endarterectomy is safe and effective in most patients.
In patients who cannot undergo endarterectomy, a newer, investigational procedure
called carotid artery stenting can be performed. Carotid stenting is performed through a
small puncture in the groin. Very small tubes (catheters), wires, and balloons are guided
up and into the carotid artery and the narrowed area is stretched open. A metal mesh tube
(stent) is implanted at high pressure into the walls of the carotid artery, allowing
increased blood flow to the brain.
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