Coloured computed tomography (CT) angiogram scan showing atheromatous plaques (white) in the abdominal aorta (upper centre) of a 68 year old male patient. Atherosclerosis is a condition in which an artery wall thickens as a result of accumulations (atheromas) of fatty materials such as cholesterol. The plaques are causing narrowing (stenosis) of the artery. Such narrowing of blood vessels raises blood pressure, and reduces blood flow to organs and tissues.