Beginning of Essay
refers to the pain arising from lack of adequate blood supply to the heart muscle. Typically, it is a crushing pain behind the breastbone in the center of the chest, brought on by exertion and relieved by rest. It may at times radiate to or arise in the left arm ....

Middle of Essay
.... by blockage to the flow of blood in those arteries supplying the heart muscle itself, i.e., the coronary arteries. Like any other organ, the heart requires a steady flow of oxygen and nutrients to provide energy for rmovement, and to maintain the delicate balance of chemicals which allow for the careful electrical rhythm control of the heart beat. Unlike some other organs, the heart can survive only a matter of minutes without these nutrients, and the rest of the body can survive only minutes without the heart--thus the critical nature of these syndromes. Causes of blockage range from congenital tissue strands within or over the arteries to spa ....