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 heart disease. Coronary heart disease (CHD) is the leading cause of heart attacks. CHD is a condition in which the coronary arteries (the major blood vessels that supply the heart with blood) get clogged up with deposits of cholesterol. These deposits are called plaques.
Examples of heart-related causes of chest pain include: 1  Heart attack. A heart attack is a result of a blood clot that's blocking blood flow to your heart muscle.  Angina. Thick plaques can gradually build up on the inner walls of the arteries that carry blood to your heart.