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.
1 AED History. 2  Heart attack (cardiac arrest) became a leading cause of death after the turn of the century. Humans have always suffered from cardiac problems, but they usually died from causes such as infectious disease, long before reaching an age where heart problems threatened their life.