What is atherosclerosis and how does it develop?

Watch this animation to better understand this medical condition:

Atherosclerosis, commonly referred to as the “hardening of the arteries”, is a progressive disease which causes a person’s arteries to become narrow 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.