is due to the deposition of CHOLESTEROL into the walls of arteries. The process starts in childhood with the development of fatty streaks lining the arteries. In adulthood these progress, scarring and calcifying to form irregular narrowings within the arteries and eventually leading to blockage of the vessel. The consequence of the narrowing or blockage depends on which vessels are involved – diseased cerebral vessels cause strokes; coronary vessels cause angina and heart attacks; renal vessels cause renal failure; and peripheral arteries cause limb ischaemia (localised bloodlessness).

Risk factors predisposing individuals to atherosclerosis include age, male gender, raised plasma cholesterol concentration, high blood pressure, smoking, a family history of atherosclerosis, diabetes and obesity.

occurs in a variety of conditions that produce inflammation in the arteries. Examples include giant cell arteritis (temporal arteritis), a condition usually affecting the elderly, which involves the cranial arteries and leads to headache, tenderness over the temporal arteries of the side of the head and the risk of sudden blindness; Takayasu's syndrome, predominantly affecting young females, which involves the aortic arch and its major branches, leading to the absence of pulse in affected vessels; polyarteritis nodosa, a condition causing multiple small nodules to form on the smaller arteries; and syphilis – now rare in Britain – which produces inflammation of the aorta with subsequent dilatation (aneurysm formation) and risk of rupture.