Harvard Heart Letter

Carotid artery ultrasound: Should you have this test?

This screening test is simple and painless, but it isn’t appropriate for most people.

For years, for-profit companies have mailed offers for health screening tests to homes across the United States. For about $150, you can undergo a series of ultrasound scans, which the companies claim can uncover potentially dangerous cardiovascular conditions. One scan looks at your carotid arteries, which run up either side of your neck.

Just like arteries in the heart and elsewhere in the body, the carotid arteries can become clogged with fatty deposits. Narrowing of a carotid artery (also called carotid artery stenosis) can increase the risk of stroke — the narrower the artery, the higher the risk.

Needless worry

But unless you have symptoms (see “Signs and symptoms of carotid artery stenosis”) or multiple risk factors for heart disease, a carotid artery ultrasound doesn’t make sense, says Dr. Marc Schermerhorn, chief of vascular surgery at Harvard-affiliated Beth Israel Deaconess Medical Center.

This is particularly true for the commercial scans, which are often done in churches, recreation centers, or mobile vans instead of accredited medical facilities. “The scans are sensitive, so there’s a good chance of seeing something if there is narrowing. But they aren’t specific, so the scan may appear abnormal when there is nothing wrong, and you may end up worrying needlessly,” says Dr. Schermerhorn.

Even at major medical centers, scans should be done judiciously. In general, screening tests make sense when a common, serious disease can be found early — and when the treatment is more effective if it’s done before the symptoms appear. But the situation with carotid artery stenosis is a bit complicated.

Signs and symptoms of carotid artery stenosis

Carotid artery stenosis usually doesn’t cause symptoms unless the artery is severely narrowed or completely blocked. One possible sign is a distinctive whooshing sound called a bruit (pronounced BREW-ee) that a doctor can hear though a stethoscope placed over the artery.

Some people experience symptoms of a transient ischemic attack (TIA) or mini­stroke, which usually last only briefly and disappear within 24 hours. They often include eye issues, most commonly a sudden loss of vision that people often describe as a curtain coming down over one eye. Others include trouble speaking or sudden weakness in the face, arms, or legs.

If you have any of these symptoms, even if they pass quickly, call 911 right away. These are also the warning signs of an imminent full-blown stroke. For more information, see the American Stroke Association’s list online at http://www.strokeassociation.org/warningsigns.

Serious stenosis is uncommon

As the fifth leading cause of death, strokes are both common and serious. The vast majority are ischemic strokes, meaning they are caused by an interruption of blood flow to the brain, most often because of a clot. About 10% to 20% of ischemic strokes can be traced back to carotid artery stenosis. Only about one in 100 otherwise healthy people has serious carotid artery stenosis, defined as a blockage of 70% or greater.

Treatments for carotid artery stenosis include medications, surgery, or placement of a stent, a tiny metal coil to prop open the artery. But the procedures themselves can trigger a stroke. So unless a person has symptoms, doctors don’t usually recommend those invasive treatments if the carotid artery blockage is less then 70%.

People who might consider a carotid artery scan include those with a number of risk factors for cardiovascular disease, such as a smoker who has high blood pressure, elevated cholesterol levels, and a parent or sibling with a history of cardiovascular disease. “If I’m evaluating someone for blockages in their leg arteries, I may advise them to get a carotid artery scan as well,” says Dr. Schermerhorn. Clogged leg arteries often cause pain when people walk (unlike carotid narrowing, which rarely causes symptoms). People with narrowed arteries in one part of their body likely have the problem in other areas, he notes.

The power of visualization

Some physicians argue that even for people with a high risk of stenosis, it makes more sense to spend time coaching people about how to better control their risks than to scan their carotid arteries.

But sometimes, a picture is worth a thousand words. “When people see a picture of the plaque that’s building up inside their carotid arteries that could potentially cause a stroke, they may be more likely to make behavior changes and take their medications,” says Dr. Schermerhorn.

Learn more about our
health content.