Atherosclerosis
The term “atherosclerosis” is derived from
two Greek words – “athero” which means “gruel” or “porridge”,
and “sclerosis” which means “hardening”.
Commonly referred to as “hardening of the arteries”,
atherosclerosis is a progressive disease which causes
arteries to become narrowed and their walls to lose elasticity
due to the accumulation of deposits on the inner lining
of these blood vessels. In patients with this condition,
substances such as cholesterol, fats, calcium, and fibrin
(clotting factors in the blood) build up into plaque
and narrow the openings of the affected arteries. As
atherosclerosis worsens, it may lead to the blood vessels
becoming so narrow as to decrease blood flow.
The exact mechanism underlying the development and progression
of atherosclerosis is not known, but many scientists
believe that it is sparked off by damage to the endothelium,
the innermost lining of blood vessels. Such damage may
be caused by a variety of factors including elevated
blood lipid levels, high blood pressure (hypertension),
and smoking. As a result of damage to the endothelium,
cellular debris, fibrin, cholesterol, and other fatty
substances deposit on the walls of arteries. The affected
arterial walls become more permeable to low-density lipoprotein
cholesterol, also known as “LDL” or “bad” cholesterol.
Once the “bad” cholesterol is oxidized, it stimulates the endothelial
cells to secrete chemical substances. This leads to further accumulation of deposits
on the walls of arteries at the site of the plaque. As the atherosclerotic lesion
develops, a lipid core builds up, damaging the arterial walls and increasing
the risk of blood clot formation (thrombosis). The innermost layer of the affected
arteries becomes thickened, with a corollary decrease in blood flow in that vessel.
Atherosclerosis can develop in any of the arteries in the body. When it occurs
in the coronary arteries supplying blood to the heart, the patient is said to
have coronary heart disease. The most common
symptom of this condition is a radiating chest pain known as angina pectoris,
or angina for short. Should coronary arteries
already narrowed by atherosclerosis become completely blocked by a blood clot
(thrombus), a heart attack ensues. |
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