Pathology of Carotid Artery Atherosclerosis

Atherosclerosis is associated with a number of well-recognized systemic risk factors such as hyperlipidemia, hypertension, cigarette smoking, and diabetes mellitus. Atherosclerotic plaque formation is a localized rather than diffuse process, however, and preferentially affects certain segments of the arterial tree such as the carotid, coronary, and lower extremity arteries, while sparing others such as the upper extremity vessels.

Arteriosclerotic plaques in the carotid circulation usually form at the origin of the common carotid artery as it arises from the aortic arch, at the bifurcation of the common carotid artery in the neck, or intracranially in the siphon portion of the internal carotid artery. Most clinically significant carotid plaques are localized in the carotid bifurcation, making surgical treatment by endarterectomy possible. Little plaque formation occurs in the common carotid artery proximal to the bifurcation or in the internal carotid artery distal to the carotid sinus. The unique and focal pattern of plaque formation in the arterial tree at branch points and bends has been attributed to local hemodynamic conditions and to differences in artery wall susceptibility, and these have been studied most extensively at the carotid bifurcation.