Fibrous tissue is formed from special cells that are produced everywhere in the body when a repair job is needed; for example, a few days after a large cut or surgical wound is stitched, fibrous tissue cells move in to form a bridge, which transforms over the next few weeks into a scar. Some scars are smooth and some are bumpy and rough. Plaques of atheroma are also sometimes smooth or bumpy and rough. These tough scars in the inner wall of the arteries are perhaps nature’s way of patching and healing. Because the vessel wall affected by atheroma gets hardened and the medical word for hardness is sclerosis, the term used for this disease is atherosclerosis.
Plaques of atheroma are most common in the abdominal aorta where it divides to form the vessels to the pelvis and lower limbs, in the coronary arteries, in the carotid arteries to the neck and brain, and in the vessels of the lower limbs.

When atherosclerosis in the coronary arteries causes symptoms, doctors use the term ‘‘atherosclerotic heart disease,’’ coronary artery disease, or coronary heart disease (CHD). Many doctors use the term ischemic heart disease because ischemia means a lack of blood and/or oxygen FIGURE 1 Obstruction of the coronary artery by plaques of atheroma that jut into the lumen and deprives the heart muscle of adequate blood supply¼myocardial ischemia manifested by chest pain [angina] and reflected on the ECG by characteristic ST segment depression. (1) Smooth lining of vessel; (2) atheroma plaque filled with a variable amount of lipid material, foam cells and other substances [appearance of porridge-like gruel]; (3) a fibrous cap that may be firm and durable prevents rupture, or a thin fragile cap prone to rupture; and (4) rupture of the plaque initiates thrombosis¼atherothrombosis. (From Khan, M. G., and Marriott, H. J. L. (1996). Heart Trouble Encyclopedia, p. 6, Toronto, Canada: Stoddart Publishing Co.) caused by poor delivery of blood from arteries to the tissue. Angina, heart attacks, heart failure, and arrhythmias are the main manifestations of CHD.

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