This section explains what happens when someone develops heart failure.
Heart failure can involve the left side of the heart, the right side or both.
However, it usually affects the left side first. The atrium receives blood into the heart, and the ventricle pumps it where it needs to go. Heart failure occurs when any of these chambers lose their ability to keep up with the amount of blood flow. Oxygen-rich blood travels from the lungs to the left atrium, then on to the left ventricle, which pumps it to the rest of the body. Because this chamber supplies most of the heart's pumping power, it's larger than the others and essential for normal function.