According to WebMD, a leaky heart valve is a valve in the heart that leaks blood during normal contraction or relaxation. There are four valves of the heart that may become leaky.
WebMD states that the four heart valves include the tricupsid valve, the pulmonic valve, the mitral valve and the aortic valve. Each of these heart valves consist of flaps that open and close to allow blood to flow in one direction as it travels through the chambers of the heart. The valves normally close to prevent back flow of blood. When a valve becomes leaky, the valves may not close properly, and blood can begin to flow back through the valve.