Coronary Heart Disease, chronic illness in which the coronary arteries, the vessels that supply oxygen-carrying blood to the heart, become narrowed and unable to carry a normal amount of blood. Most often, the coronary arteries become narrowed because of atherosclerosis, a process in which fatty deposits called plaque build up on the inside wall of an artery.
Plaque is made of oily molecules known as cholesterol, fibrous proteins, calcium deposits, tiny blood cells known as platelets, and debris from dead cells. When its blood supply is reduced, the heart does not receive sufficient oxygen. This oxygen deficit leads to two main consequences: chest pain known as angina pectoris, and heart attack, in which part of the heart dies because of oxygen deprivation. Coronary heart disease is the leading cause of death in the United States, responsible for about 515,000 deaths each year. (Encarta Encyclopedia)