A leaking mitral valve allows blood to flow in two directions during the contraction. Some blood flows from the ventricle through the aortic valve – as it should – and some blood flows back into the atrium.
A leaking (or regurgitant) aortic valve allows blood to flow in two directions. Oxygen-rich blood either flows out through the aorta to the body – as it should – or it flows backwards from the aorta into the left ventricle when the ventricle relaxes.
Leaking valves can cause the heart to work harder to pump the same amount of blood.