ärtĭrˌēōsklərōˈsis, general term for a condition characterized by thickening, hardening, and loss of elasticity of the walls of the blood vessels. These changes are frequently accompanied by accumulations inside the vessel walls of lipids, e.g., cholesterol; this condition is frequently referred to as atherosclerosis. Initially lesions are formed on the arterial walls, which results in blistering and the accumulation of low-density cholesterol. This produces higher blood pressure, which facilitates the imbedding of cholesterol and calcium in the vessel walls. The fatty material accumulates calcium and produces hard plaques, thus hardening the walls of the vessels. As the vessel walls thicken, the passageways through the vessels narrow, decreasing the blood supply to the affected region. Constriction of the coronary arteries may affect the heart (see coronary artery disease, heart disease). If the leg vessels are affected, there may be pain with walking and an onset of gangrene. When there is total clotting of a vessel ( thrombosis) the result may be a heart attack (if it occurs in the coronary arteries) or stroke (if in cerebral arteries).

Arteriosclerosis risk factors include hypertension, elevated levels of fats in the blood, cigarette smoking, diabetes mellitus, and obesity. Genetic risks are related to the ability of the body to process (uptake and metabolize) low-density lipids that contain cholesterol. Reduction of body cholesterol to normal levels through cholesterol-lowering drugs and a restricted-fat diet is usually prescribed. The latter generally entails substitution of vegetable fats for animal fats, but an exception may be "trans fat," artificially hydrogenated vegetable oils found in margarine and vegetable shortening, which studies have linked to increased risk of coronary disease. Treatment of hypertension, stress management, and cessation of smoking are also important. Increasing consumption of antioxidants and folic acid may be protective. Surgical treatment that bypasses clogged areas or procedures such as angioplasty are sometimes necessary; gene therapy that forces the growth of new blood vessels bypassing an area has also been used. Exercise often can increase utilization of excess low-density lipids. Although the relationship between blood cholesterol levels and arteriosclerosis is not fully understood, the utilization of low-density lipids appears to be a primary indicator of the risk of arteriosclerosis.

The Columbia Encyclopedia, Sixth Edition Copyright© 2004, Columbia University Press. Licensed from Lernout & Hauspie Speech Products N.V. All rights reserved.

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