A Heart Attack occurs when the blood supply to part of the heart muscle, or myocardioum, is severely reduced or stopped. The medical term for heart attack is myocardial infarction. The reduction or stoppage happens when one or more of the coronary arteries supplying blood to the heart muscle are blocked. This is usually caused by the buildup of plaque (deposits of fat-like substances), a process called atherosclerosis. The plaque can eventually burst, tear or rupture, creating a “snag” where a blood clot forms and blocks the artery, depriving part of the heart of oxygen and nutrients. This leads to a heart attack. If the flow of blood is not restored within a few minutes, the affected muscle cells can suffer permanent damage or die. A heart attack is also sometimes called a coronary thrombosis or coronary artery occlusion.