Atherosclerosis and cholesterol
When plaque (fatty deposits) clogs your arteries, that’s called atherosclerosis. These deposits are made up of cholesterol, fatty substances, cellular waste products, calcium and fibrin (a clotting material in the blood).
As plaque builds up, the wall of the blood vessel thickens. This narrows the channel within the artery, which reduces blood flow. That, in turn, lessens the amount of oxygen and other nutrients reaching the body.
Where plaque develops, and the type of artery affected, varies with each person. Plaque may partially or totally block blood flow through large- or medium-sized arteries in the heart, brain, pelvis, legs, arms or kidneys. This can precipitate various conditions, including:
- Coronary heart disease (plaque in arteries in or leading to the heart)
- Angina (chest pain from reduced blood flow to the heart muscle)
- Carotid artery disease (plaque in neck arteries supplying blood to the brain)
- Peripheral artery disease, or PAD (plaque in arteries of the extremities, especially the legs)
- Chronic kidney disease
Plaque presents a double threat.
Plaque itself can pose a risk. A piece of plaque can break off and be carried by the bloodstream until it gets stuck. And plaque that narrows an artery also allows for the possibility that a blood clot (thrombus) may adhere to the blood vessel’s inner wall.
If either case, the artery can be blocked, cutting off blood flow.
If the blocked artery supplies the heart or brain, a heart attack or stroke occurs. If an artery supplying oxygen to the extremities (often the legs) is blocked, gangrene, or tissue death, can result.
How it starts, how it progresses
Atherosclerosis is a slow, progressive disease that may start in childhood. In some people, atherosclerosis progresses rapidly in their 30s. In others, it doesn’t become dangerous until they reach their 50s or 60s. (Some hardening of the arteries is normal as people age.)
Exactly how atherosclerosis starts or what causes it isn’t known.
Many scientists believe plaque begins when an artery’s inner lining (called the endothelium) becomes damaged. Three possible causes of such damage are:
Smoking has a big role in the progression of atherosclerosis in the aorta (the body’s main artery), coronary arteries and arteries in the legs. Smoking makes fatty deposits more likely to form, and it accelerates the growth of plaque.