Coronary artery disease is caused by atherosclerosis, or hardening of the arteries. The term originates from the Greek words athero (gruel, or paste) and sclerosis (hardness). It's a process in which artery walls accumulate plaque — a waxy, fatty substance that contains cholesterol, cellular waste products, calcium and a blood-clotting protein called fibrin.
Arteries are hollow tubes that transport blood throughout our bodies. The walls of arteries are made of smooth, elastic muscle cells. A cell layer called the endothelium (pronounced en-do-THEE-lee-um; Greek for "inner layer") lines the artery walls and serves as a protective barrier between the blood stream and artery walls.
As you age, several factors can damage the endothelium:
- High levels of fats — cholesterol and triglycerides — in the bloodstream.
- Hypertension (high blood pressure), which puts pressure on artery walls.
- Smoking tobacco, which interferes with chemicals released by the endothelium.
- Insulin resistance and diabetes mellitus (type 2 diabetes).
According to research, when the protective endothelium becomes damaged, plaques are allowed to cling to the exposed artery wall. Attempting to heal the damage, the artery wall may release sticky chemicals that, unfortunately, encourage further artery-clogging plaque buildup.
Plaque deposits are hard on the outside and mushy on the inside. If a crack forms in a deposit's tough exterior, the body will try to seal the rupture by releasing blood-clotting platelets. A blood clot may form, blocking blood supply to the heart muscle and posing the risk of heart attack.