Carotid atherosclerosis. Definition, pathogenesis, and clinical significance.

Atherosclerotic plaques are aggregates of plasma lipids (especially cholesterol), cells (smooth muscle cells and monocytes/macrophages), and connective tissue matrix (collagen fibers and proteoglycans). Symptomatic plaques in the carotid artery involve primarily the carotid bulb and are characterized by increased cellular proliferation, lipids accumulation, calcification, ulceration, hemorrhage, and thrombosis. Risk factors (arterial hypertension, cigarette smoking, high serum levels of cholesterol, and fibrinogen) promote thrombus formation and continuous transendothelial seepage of plasma lipids.