Medical scientists detected early atherosclerosis by uncovering vascular abnormalities in 42- to 44-year-old predominately male patients who had severe obstructive sleep apnea but no overt cardiovascular disease.

In the study, the researchers investigated the functional and structural properties of the large arteries in 15 persons with mild to moderate obstructive sleep apnea (OSA), 15 individuals with severe OSA, and 12 healthy control volunteers. All groups were matched for age, sex, and body mass index.

The participants underwent a full standard overnight sleep test (polysomnography); a pulse wave velocity test, which is a noninvasive, accurate method of determining the elastic properties of the aorta and other large arteries; and an assessment with a high definition echo-tracing device to measure carotid artery thickness, diameter, and potential enlargement.

The authors said that the mechanical properties of the large arteries are important determinants of circulatory physiology in health and disease. They noted that increased arterial stiffness preceded the onset of systemic hypertension in humans and was an independent risk marker of premature artery disease, atherosclerosis, and cardiovascular disease.

In OSA, the sleeping person repeatedly stops breathing as a result of partial or complete blockage of the upper airways. This stoppage occurs long enough to decrease the amount of oxygen in the blood and brain, and to build up carbon dioxide. After a breathing pause of 10 seconds or longer, the person usually awakens enough to resume breathing. These episodes can occur numerous times during the night.

In this study, the investigators said that an important finding was the increased carotid diameter in patients with OSA. It seems that previous studies have shown that carotid artery dilation is a compensatory mechanism in the early stages of atherosclerosis.

The authors pointed out that all vascular abnormalities detected correlated significantly with the severity of the subject’s OSA, which further supported the hypothesis that OSA plays an independent role in the progression of atherosclerosis.

The study appears in the first issue for September 2005 of the American Thoracic Society’s peer-reviewed American Journal of Respiratory and Critical Care Medicine.

Brian Kell
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American Thoracic Society
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American Thoracic Society Journal news tips for September 2005 (first issue)

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