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 causes most heart attacks and is the most common form of heart disease. The types of heart disease include: Atherosclerosis is a buildup of cholesterol, calcium and blood clotting material on the walls of the arteries. The material that builds up is called plaque.