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).
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).