Hyperlipidaemia. Illustration of the narrowing of an artery (atherosclerosis) due to high levels of lipids in the blood (hyperlipidaemia). The artery is cut through, with red blood cells and lipid particles (yellow) escaping. Lipid particles are a form of blood cholesterol. The lumen of the artery has narrowed due to lipid accumulation beneath the inner elastic wall (white) and smooth muscle (red). Calcium crystals may also form here. Hyper- lipidaemia is a metabolic disorder which may be associated with diabetes, kidney failure, or be inherited. Narrowing of the arteries increases the risk of blood clots forming, and is associated with coronary heart disease and stroke.