Compromises a minority of all symptomatic presentations. Risk factors include hypertension, smoking, diabetes, previous strokes or cardiac disease.
Process starts as fatty streaks in children and young adults.
With time the plaques enlarge, and in addition to stenosis, they may be complicated by ulceration, hemorrhage, formation of mural thrombus and depostion of calcium. At this stage the lesions are no longer restricted to the intima but involve the media, so the vessel may be weakened and an aneurysm may develop. Three theories of causation. Lipid hypothesis . Blood plasma constituents traverse the endothelium into the intima wherein they stimulate cellular proliferation and connective tissue responses.