Atherosclerosis. Light micrograph of a cross section through an artery with mild atheroma. The artery wall is pink. The formation of a fatty plaque or atheroma (gray, center) has greatly narrowed the size of the artery lumen (white, center). This causes a considerable reduction in blood flow. When this occurs in the arteries leading to the heart, symptoms of "angina pectoris" (gripping pains in the chest) are frequently experienced. In severe cases heart attacks or strokes may occur. Atherosclerosis is principally caused by high fat diets, cigarette smoking, obesity and inactivity.