Common disorder of the arteries in which patches (plaques) consisting mostly of cholesterol and lipids form on the inner arterial wall. As a result the vessels become more rigid and narrowed, leading to decreased blood flow. Atherosclerosis is also associated with high blood pressure, obesity, diabetes, and some inheritied metabolic diseases. In some cases, segments of blocked arteries may be surgically bypassed (as in coronary bypass surgery). Preventive measures include cessation of smoking, a low-fat diet, exercise, and avoidance of stress.