Pre-Algebra on Khan Academy: No way, this isn't your run of the mill arithmetic. This is Pre-algebra. You're about to play with the professionals. Think of pre-algebra as a runway.
Heart attack - Causes. Heart attacks are caused by the blood supply to the heart being suddenly interrupted. Without this supply, heart muscles may be damaged and begin to die. Without treatment, the heart muscles will experience irreversible damage.
Coronary artery disease, one type of heart disease, is the leading cause of heart attacks. The most common cause of coronary artery disease is atherosclerosis, a condition that occurs when plaque builds up in the arteries that supply blood to the heart.