Q: 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?
A: 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.
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.
• Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com.