The heart has four valves, and each valve is composed of a set of flaps called leaflets: mitral, aortic, tricuspid, and pulmonary. Every valve is subject to its own set of problems.
The tricuspid and pulmonary valves are located on the right side of the heart; they control the flow of the non-oxygenated blood from the rest of the body to the lungs so it can get oxygen enriched.
The mitral and the aortic valves are located on the left side of the heart controlling the flow of oxygen-rich blood from the lungs to the heart and eventually through the aortic valve to the rest of the body.
The aortic and mitral valves are the most commonly affected valves.