The heart is a muscular pump about the size of a fist located under the breastbone (sternum) between the lungs. There are four hollow chambers in the heart: the right and left upper chambers (atrium) and right and left lower chambers (ventricles). The heart muscle expands and contracts ("beats") and four valves open and close between the chambers and major blood vessels in an organized manner, moving the blood continuously through the chambers and into the main circulatory system. Blood brings oxygen and nutrients to all the organs and removes waste products via the lungs, kidneys and liver.
We measure a heart's function by the amount of blood it pumps. Normally the heart pumps 60 to 70 percent of the blood in it. This is called the ejection fraction (EF). When the muscle is weak or damaged, the heart can't pump blood as well and the EF falls. In order to pump more blood, the heart may increase in size and beat faster (increase pulse). We consider the heart function to be severely reduced when the EF falls to 35 percent or below.
The diagnosis of cardiomyopathy indicates there is a disease that has caused the heart muscle to enlarge. As a result, the heart cannot pump blood effectively to all of the organs and tissues in the body and fails (heart failure). Fluid backs up in the blood vessels, the lungs, liver, abdomen and legs. Because of the lack of oxygen and nutrients to the rest of the body, other organ systems also can begin to fail.