Atherosclerosis is hardening of a blood vessel from a buildup of plaque. Plaque is made of fatty deposits, cholesterol, and calcium. Plaque buildup causes the artery to narrow and harden.

Plaque buildup can slow and even stop blood flow. This means the tissue supplied by the artery is cut off from its blood supply. This often leads to pain or decreased function. This condition can cause a number of serious health problems. Depending on the location of the blockage, it can cause:

Atherosclerosis
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A hardened artery is more likely to be damaged. Repeated damage to the inner wall of an artery causes blood clots to form. The clots are called thrombi. They can lead to a further decrease in blood flow. A thrombus sometimes becomes so large that it completely closes off the artery. It could also break into clumps, called emboli. These clumps travel through the bloodstream and lodge in smaller arteries, blocking them off. The tissue supplied by the artery receives no oxygen. It quickly dies. When this occurs in the heart, it is called a heart attack. In the brain, it is called a stroke.

Long-term atherosclerosis can also cause arteries to weaken. They may bulge under pressure. This bulge is called an aneurysm. If untreated, they can rupture and bleed.

Atherosclerosis is caused by plaque. Plaque is created by high levels of cholesterol and fat in the blood. Scar tissue and calcium from vessel injury can also add to the plaque buildup.

The process leading to this may begin in childhood. It takes decades before it causes serious health problems.