Illustration copyright 2000 by Nucleus Communications, Inc. All rights reserved. http://www.nucleusinc.com

The coronary arteries provide oxygen-rich blood and other nutrients to the heart muscle. They attach to and wrap around the heart's surface.

Coronary artery disease occurs when blood flow to the heart muscle is restricted, often caused by the buildup of plaque on the inner walls of the coronary arteries. Plaque is made up of cholesterol, white blood cells, calcium, and other substances in the blood. This buildup of plaque is called atherosclerosis.