atherosclerosis /ath′ərō′sklərō″sis/ [Gk, athere, meal, sklerosis, hardening] , a common disorder characterized by yellowish plaques of cholesterol, other lipids, and cellular debris in the inner layers of the walls of arteries. Atherosclerosis may be induced by injury to the arterial endothelium, proliferation of smooth muscle in vessel walls, or accumulation of lipids in hyperlipidemia. The condition begins as a fatty streak and gradually builds to a fibrous plaque or atheromatous lesion. The vessel walls become thick, fibrotic, and calcified, and the lumen narrows, resulting in reduced blood flow to organs normally supplied by the artery. The plaque eventually creates a risk for thrombosis and is one of the major causes of coronary heart disease, angina pectoris, myocardial infarction, and other cardiac disorders. Plaque rupture is usually provoked by activation of the sympathetic nervous system, such as sudden awakening, heavy physical exertion, or anger. See also arteriosclerosis. −atherosclerotic, adj. ▪ OBSERVATIONS: Atherosclerosis usually occurs with aging and is often associated with tobacco use, obesity, high homocysteine levels from eating red meat, hypertension, elevated low-density lipoprotein and depressed high-density lipoprotein levels, and diabetes mellitus. ▪ INTERVENTIONS: Antilipemic agents do not reverse atherosclerosis. Segments of arteries obstructed or severely damaged by atheromatous lesions may be replaced by patch grafts or bypassed, as in coronary bypass surgery; the lesion may be removed from the vessel via endarterectomy; or obstructed arteries may be opened by balloon angioplasty or by the insertion of stents. ▪ PATIENT CARE CONSIDERATIONS: A diet low in cholesterol, calories, and saturated fats, together with avoidance of smoking, stress, and a sedentary lifestyle, may help prevent the disorder.
