A heart attack, which also called a myocardial infarction, occurs when the blood supply to an area of the heart becomes suddenly cut off by a blockage in one of the arteries to the heart. This part of the heart muscle dies and therefore the heart functions less efficiently. The usual cause of the blockage is the result of a gradual 'furring up' (or atheroma) of one of the coronary (heart) arteries. A complete blockage is caused by a blood clot lodging inside the already narrowed artery.
The basic cause of all heart attacks is the same but there are different types of heart attack depending on what part of the heart is affected and whether a large or small area of heart muscle is killed in the attack. Usually the left side of the heart is involved, as this is the side that has the largest muscle area. Heart attacks can be so small as to go almost unnoticed or large enough to cause sudden death.
