Heart Attack A heart attack or myocardial infarction is the death of a part of the heart muscle caused by the sudden loss of blood supply. This loss of blood supply to the heart is due to a blockage of a coronary artery by a blood clot on a cholesterol plaque located on the inner wall of an artery of the heart.
Cholesterol is a fatty chemical which is part of the outer lining of cells in the body.
Cholesterol plaque is the formation of a hard, thick substance within the artery walls which is caused by deposits of cholesterol in the artery walls. During exercise or excitement, the blocked coronary arteries cannot increase the blood supply to meet the increased oxygen demand of the heart muscle. Thus the heart muscle is deprived of blood oxygen. This may result in chest pain or angina pectoris. When the narrowing in the artery becomes critical, unstable angina may result.