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.
Heart attack - Causes. Heart attacks are caused by the blood supply to the heart being suddenly interrupted. Without this supply, heart muscles may be damaged and begin to die. Without treatment, the heart muscles will experience irreversible damage.
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).