A heart attack is a sudden serious medical condition in which someone's heart stops working, causing them great pain. It is the most common of the heart diseases and occurs when blood flow to the heart and part of it is blocked, often by a blood clot, which is a thick almost solid mass formed when blood dries.
This situation is usually caused by arteriosclerosis a disease in which arteries become hard, stopping the blood from flowing through them smoothly. Sometimes, the clot is called coronary thrombosis or coronary occlusion, since is often caused by rupturing or tearing of plaque in an artery.

Muscle cells damaged and die, if blood supply is cut off for a long time, leading to disability or death depending on the extent of the damage to the muscle.
A heart attack it is also known as myocardial infarction, which can also occur when a coronary artery temporarily contracts or goes into spasm, decreasing or cutting the blood flowing to the heart.
A heart attack represents on or about half of all coronary heart disease deaths and can be caused by nearly all types of heart illness.
There exist three main symptoms to know when a heart attack occurs. One is the pressure or pain in the centre of the chest, lasting more than a few minutes or going away and coming back. A second symptom is when pain spreads to the shoulders, neck or arms. A third symptom consists in a chest discomfort combined with light-headedness, fainting, sweating, nausea or shortness of breath.