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).
Atherosclerosis is the usual cause of heart attacks, strokes, and peripheral vascular disease -- what together are called  cardiovascular disease .. Cardiovascular disease is the No. 1 killer in America, with more than 800,000 deaths in 2005. Coronary artery disease: Stable plaques in the heart's arteries cause angina (chest pain on exertion). 2  Sudden plaque rupture and clotting causes heart muscle to die. 3  This is a heart attack, or myocardial infarction.