Heart Attacks

A heart attack, or myocardial infarction, happens when the blood supply to part of the heart muscle is cut off.Cause. A coronary artery becomes completely blocked, usually by a thrombus that forms where an atheroma has broken through the endothelium, or by an embolus lodging in the artery. The heart muscle beyond the blockage receives no oxygen. It cannot respire aerobically, and if the blood supply is not restored within a short time, the muscle cells die. The area of dead tissue is called an infarct.Size of the damage. The amount of heart muscle affected depends on where the blockage is. The closer the blockage is to the start of the coronary artery, near the aorta, the larger the area of heart muscle that is supplied beyond it, so the larger the area damaged. A large area of damage may stop the heart pumping effectively and can be fatal. It can also disrupt the electrical activity of the heart, causing cardiac arrest.Symptoms include severe, crushing chest pain that does not go away with rest, pain spreading to the left arm, neck or jaw, shortness of breath, sweating and nausea.Treatment. Speed matters, because the longer the muscle is without oxygen, the more cells die. Aspirin is given to reduce further clotting. Thrombolytic (clot-busting) drugs can be used to dissolve the clot, or the artery can be reopened by angioplasty and a stent. Survivors may be left with damaged heart muscle and a higher risk of further heart attacks and heart failure.