A heart attack happens when part of the heart muscle does not receive the supply of oxygen-rich blood that it needs to function. When the blood supply stops flowing to that part of the heart muscle, that muscle area dies. This can cause an abnormality in the rhythm or rate of the heartbeat, a condition called arrhythmias (a-rith-me-ahs). These arrhythmias can lead to cardiac arrest, in which breathing and heart function stop.

What are the causes and risks of the injury?

The causes of a heart attack usually involve blood-clot formation or a spasm of one of the arteries that supplies blood directly to the heart muscle. These arteries are called coronary arteries. When the blood is blocked to a part of the heart muscle, the oxygen-rich blood that is needed by that part of the heart cannot reach it. As a result, the cells in that area are damaged or die. This usually occurs when the coronary artery has been narrowed due to a build-up of fatty deposits in the arteries, a condition known as atherosclerosis (ath-er-oh-skler-oh-sus).