Atherosclerosis Is the hardening and narrowing of the arteries. It is caused by the slow buildup of plaque inside the artery walls. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. As it grows, the buildup of plaque narrows the inside of the artery and, in time, may restrict blood flow. There are two types of plaque: hard and stable or soft and unstable. Hard plaque causes artery walls to thicken and harden. Soft plaque is more likely to break apart from the walls and enter the bloodstream. This can cause a blood clot that can partially or totally block the flow of blood in the artery. When this happens, the organ supplied by the blocked artery starves for blood and oxygen. The organ's cells may either die or suffer severe damage.
Atherosclerosis is a slow, progressive disease that may start in childhood. It can affect the arteries of the brain, heart, kidneys, and the arms and legs. As plaque builds up, it can cause serious diseases and complications. These include: coronary artery disease, angina, heart attack, sudden death, cerebrovascular disease, stroke, transient ischemic attack, or "mini strokes" peripheral arterial disease.