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.
There are a few cardiac conditions that can cause heart attacks. One of the most common causes is plaque buildup in the arteries (atherosclerosis) that prevents blood from getting to the heart muscle. Heart attacks can also be caused by blood clots or a torn blood vessel. Less commonly, a heart attack is caused by a blood vessel spasm.