Except the mitral valve, each valve typically has three flaps. The mitral valve has two flaps. Any of the four valves can become leaky. This means that just after the heart squeezes and pumps blood forward, some blood will leak backward through the valve. Leaking through the valve is also called valve regurgitation.ny of the four valves can become leaky. This means that just after the heart squeezes and pumps blood forward, some blood will leak backward through the valve. Leaking through the valve is also called valve regurgitation.