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Wednesday, May 7, 2014

Why would a doctor order an ultrasound of the carotid artery?

DEAR DOCTOR K:

My father’s doctor wants him to have an ultrasound of his carotid
artery. What is the carotid artery? What will the doctor be looking for?


DEAR READER:

The carotid arteries carry oxygen- and nutrient-rich blood from the
heart to the brain. These crucial arteries can become narrowed by the
cholesterol-filled plaques of atherosclerosis. Blood clots can form from
the plaques, then break off and travel to the brain. There, they can
lodge in small arteries, interrupting the vital flow of blood to brain
cells, you can see an example of this below.



Brain at risk: The carotid circulation

N0811a-1The
internal carotid artery carries blood to the brain. Cholesterol-laden
plaques can narrow the artery, allowing clots to form. If the clots
break off and travel to the brain, they can cause transient ischemic
attacks (TIAs) or strokes.

Brief or partial interruptions of blood flow to the brain can cause
transient ischemic attacks (TIAs). TIAs cause temporary symptoms but no
permanent damage. But a prolonged or substantial interruption of blood
flow to the brain can cause a stroke. During a stroke, brain cells die,
often damaging a person’s ability to move, speak, feel or think.


A carotid ultrasound can detect whether your father has narrowing, or
stenosis, of his carotid arteries. If so, he may be at an increased
risk of stroke.


Carotid ultrasound is the most widely used test for carotid stenosis.
It is quick and safe. Ultrasound is similar to radar. Developed just
before the beginning of World War II, radar machines sent out and
received radio waves: They had both transmitters and receivers. The
machine would send out waves that would bounce off an object (like a
distant airplane). The waves that bounced back from the object were
picked up by the receiver. The time that elapsed between sending and
receiving the radio waves would tell the radar machine that there was an
object out there, and how far away it was.


Ultrasound uses sound waves rather than radio waves. During the test,
an ultrasound probe on your neck beams sounds waves through your skin,
and then through the carotid artery. A computer translates the sound
signals into an image of your carotid artery and the blood flowing
through it. It can show a plaque that has slowed blood flow.


Current guidelines recommend against carotid screening for everyone.
That’s because most people do not have plaques in their carotid
arteries, so there would be nothing to see. The test is reasonably
expensive, and it’s not perfectly accurate.


If your father’s doctor wants him to have a carotid ultrasound, I’ll
bet it’s because your father had some symptoms of carotid stenosis.
These symptoms are usually temporary. They may include visual
abnormalities, weakness, numbness, tingling or slurred speech.


If the ultrasound reveals carotid stenosis, your father will have two
treatment options: medication to prevent clot formation, or a procedure
to open the narrowed artery. Both treatments will help prevent a
stroke.


The best way to prevent TIAs and strokes is to keep your blood vessels healthy:


  • Don’t smoke.
  • Eat a healthy diet.
  • Exercise regularly.
  • Maintain healthy blood pressure and cholesterol levels.
Reblogged from Ask Doctor K



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