What is a heart attack?

A heart attack occurs when the flow of blood through a coronary artery is blocked, preventing an area of heart muscle from being supplied with oxygen and nutrients. As a result, the heart's ability to pump blood around the body is impaired. Heart attacks are caused by coronary artery disease. Over time, fatty deposits build up in the wall of an artery and form a plaque (this is sometimes called atherosclerosis). If the plaque is unstable, it may rupture. When it ruptures, it leaves a rough surface on the artery, where a blood clot can then form. If this blood clot then breaks away and gets stuck downstream in the artery, it can block the artery and cause a heart attack.Extension: What do you think determines the severity of a heart attack?