Question

In humans, what is the results when a valve is leaking blood backward in the heart

Answer 1

This causes a phenomenon referred to as valve regurgitation. This reduces the flow of blood in the blood vessels and causes a reduction in the oxygenation of tissues of the body. This causes homeostatic signaling by the body resulting in the exertion of the heart pumping and increased breathing (heavy breathing). This is why some of the symptoms include shortness of breath,   fatigue, and light-headedness.