Mitral Valve Replacement Mitral valve replacement surgery is a common type of open heart surgery. The mitral valve is located on the left side of the heart, and is the vessel through which oxygenated blood is transported from the lungs into the heart. Since the heart requires plenty of oxygen to keep functioning properly, mitral valve malfunctions can cause severe health concerns over time. Mitral valve replacement is required in one of two scenarios, when the mitral valve does not open completely and when it does not close completely. When the mitral valve does not fully open it does not allow enough oxygenated blood into the heart, and when it does not fully close the blood leaks back into lungs and overexerts the heart, which now has to work harder to pump more blood out to the body. For patients facing mitral valve replacement surgery, there are a few different surgical options. The mitral valve can either be repaired by a cardiothoracic surgeon or it can be replaced with either mechanical or biological valve. Mitral valve replacement with a mechanical valve has the benefit of never wearing out. The biggest downfall to mechanical mitral valve replacement surgery is that blood tends to clot around the mechanical valve, requiring the patient to remain on blood thinning medication for the remainder of their life. Biological mitral valve replacement can be achieved with a cadaver, cow or pig mitral valve. Though biological mitral valve replacements do not require lifetime blood thinners, they are much more likely to wear out and need replacement after years of activity.