Atherosclerosis refers to a major cause of heart disease; caused by the narrowing of the arterial walls due to the formation of plaques that reduce the flow of blood through the arteries and interfere with the passage of nutrients from the capillaries into the cells. It is a disease characterized by gradual narrowing of the coronary arteries; a disease caused by the accumulation of fatty substances in the blood vessels. It is a pathological condition in which fatty substances collect inside the lumen of arteries; the formation of plaque within the arteries.