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.
The most common cause of a heart attack (myocardial infarction) is a blood clot that lodges in an artery and blocks blood flow to the heart muscle.This often causes a painful pressure, cramping or squeezing sensation in the chest. The discomfort can refer from your chest into your back.he most common cause of a heart attack (myocardial infarction) is a blood clot that lodges in an artery and blocks blood flow to the heart muscle.