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.
Coronary artery disease. The most common underlying cause of heart attack is atherosclerosis, a condition in which a fatty substance called plaque builds up on the inside walls of blood vessels. When this occurs in the coronary arteries, it's known as coronary artery disease (CAD).
A heart attack is injury to the heart muscle caused by a loss of blood supply. While heart attacks can be caused by an unhealthy life style, lack of exercise, poor diet, and stress, recently, heart attacks have been linked to a number of defective drugs, including Vioxx, Bextra, Celebrex and Zelnorm.