Heart attack or an acute myocardial infarction occurs when a blood vessel in the heart unexpectedly will become blocked. Blood vessels carry blood and oxygen. When a blood vessel inside the coronary heart gets blocked, blood cannot get to a part of the heart. This a part of the heart does not get enough oxygen. This is known as ischemia. When the coronary heart muscle will become ischemic (does now not get sufficient blood and oxygen), the ischemia regularly reasons chest pain. This is known as angina pectoris. If the ischemia lasts long enough, the coronary heart muscle that is not getting enough oxygen dies. This is referred to as an infarction (muscle death) in the coronary heart muscle.