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.
1 Heart attacks cause scarring of the heart tissue. 2  Scarred heart tissue interfere with the proper movement of electrical impulses which make the heart beat. 3  The heart may beat too fast (ventricular tachycardia) or irregularly (ventricular fibrillation). 4  Cardiomyopathy-disease of the myocardium (heart muscle).