What happens during heart failure?

See below. Because the heart is weakened, it cannot pump the blood forward normally. This produces symptoms such as fatigue. Also the pressure rises within the heart resulting in a build up of fluid in the lungs and eventually involving the right side of the heart so that there is leg swelling. The body responds to the low output by releasing certain hormones which worsen the swelling. It is complex.
Heart failure. Heart failure means the heart is not pumping adequate output to satisfy the bodies needs. Usually this results in fluid retention, fatigue, edema, and shortness of breath. There is a form called diastolic failure in which the heart pumps adequately but to do this requires high intracranial pressures and fluid retention.