Carotid Artery Ultrasound - Diagnosing Heart Disease: Heart Disease

Content provided by the Faculty of the Harvard Medical School

Carotid artery ultrasound

This screening test may be useful for some people, including those with no known coronary artery disease. It uses sound waves to construct an image of the carotid arteries in the neck, the most important blood vessels supplying the brain. The test can measure the thickness of the inner layers of these arteries and reveal any obstructions. The inner layers — called the intima and the media — get thicker as cholesterol and other lipids begin to collect. In other words, this procedure lets the physician peek inside the carotid arteries and assess their health.

Several large epidemiological studies have shown that the technique can be used to assess the risk of having a heart attack or stroke. For instance, the Cardiovascular Health Study followed 4,476 elderly people without known coronary artery disease for an average of 6.2 years. During this follow-up period, researchers observed a striking relationship between thickening of the carotid arteries' intima and media and risk for heart attack or stroke.

The participants with the thickest intima-media layers had nearly four times the risk of suffering a heart attack or stroke as those with the thinnest layers. A number of clinical trials have also shown that lipid-lowering drugs help reduce the thickness of these layers — which indicates that atherosclerosis may actually be regressing. However, two challenges remain. First, methods of measuring carotid thickness are not yet standardized, limiting the test's value as a diagnostic tool. Second, no studies have demonstrated that having a carotid ultrasound test influences whether people who have no heart disease symptoms live longer.

Last updated:	May 03, 2007