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how does a heart attack occur?
A heart attack occurs when blood flow to part of the heart is blocked, often by a blood clot, causing damage to the affected muscle. The clot, often caused by rupturing or tearing of plaque in an artery, is sometimes called a coronary thrombosis or a coronary occlusion.

If blood supply is cut off for a long time, the muscle cells are irreversibly damaged and die, leading to disability or death depending on the extent of the damage.

Diseases that narrow the coronary arteries can reduce the supply of blood and cause a shortage of oxygen and essential nutrients in the heart muscle. This triggers chest pain known as angina, especially when the heart is made to work extra hard, for example during exercise.
A heart attack can occur if the shortage of oxygen to an area of heart muscle is severe and prolonged. Heart attacks (also known as a myocardial infarction or MI) can also occur when a coronary artery temporarily contracts or goes into spasm, decreasing or cutting the flow of blood to the heart.


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