To understand what heart failure is, you first need to know what the healthy heart does. Every cell in our body needs a constant supply of oxygen and nutrients. And every cell needs to eliminate carbon dioxide waste. Your cardiovascular system ensures that blood moves efficiently through the body to meet these needs. Your heart is at the center of the circulatory system. It pumps blood through the bodys blood vessels, to every cell in the body. As the blood rushes by, it delivers oxygen and nutrients to the cells and picks up carbon dioxide.

Your heart pumps approximately 100,000 times a day. The heart is made up of four chambers that are organized into two separate pumping systems-one on the right and one on the left. The upper chambers are called atria. The lower chambers are the ventricles.

Oxygen-poor blood enters the hearts right side-first the atrium, then the ventricle. The right ventricle pumps the blood to the lungs to receive fresh oxygen. From the lungs, the blood flows to the hearts left side-first the atrium and then the ventricle. Finally, the left ventricle walls contract powerfully to push the blood out of the heart and into the body. In this way, a healthy heart ensures that the body has a constant supply of oxygen-rich blood.