This occurs when one of the coronary arteries that supply blood to the heart muscle is blocked. The heart is a muscle that pumps oxygen-filled blood to all parts of the body. In healthy adults, the heart is usually about the size of a closed fist and pumps approximately 1,900 gallons of blood through the circulatory system every day.
Blood flows out from the heart through the aorta, which is the largest artery in the body.
All of the major arteries branch from the aorta and carry blood to all parts of the body. After picking up oxygen from the lungs, the blood is pumped out to the body again. As the heart pumps, it produces a pulse. Counting the pulse tells us how many times the heart pumps or beats per minute. Like any other muscle, the heart needs oxygen to live and work.