What is Atherosclerosis?

Atherosclerosis (ath-er-o-skle-RO-sis) is the hardening and narrowing of the arteries. It is caused by the slow buildup of plaque (plak) on the inside of walls of the arteries. 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 your blood. As it grows, the buildup of plaque narrows the inside of the artery and, in time, may restrict blood flow. Plaque can be:

• Hard and stable, or
  
• Soft and unstable.
  

Causes, incidence, and risk factors

Atherosclerosis is a common disorder of the arteries. Fat, cholesterol, and other substances accumulate in the walls of arteries and form "atheromas" or plaques.

Eventually, this fatty tissue can erode the wall of the artery, diminish its elasticity (stretchiness) and interfere with blood flow. Plaques can also rupture, causing debris to migrate downstream within an artery. This is a common cause of heart attack and stroke.

Clots can also form around the plaque deposits, further interfering with blood flow and posing added danger if they break off and travel to the heart, lungs, or brain. Many physicians now suspect that there is an immune system component to the problem (inflammation may help cause atherosclerosis).

When blood flow in the arteries to heart muscle becomes severely restricted, it leads to symptoms like chest pain.

Risk factors include smoking, Diabetes, obesity, high blood cholesterol, a diet high in fats, and having a personal or family history of heart disease. Cerebrovascular disease, peripheral vascular disease, high blood pressure, and kidney disease involving dialysis are also disorders that may be associated with atherosclerosis.

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: