Abstract: A pivot mechanism for a mechanical heart prosthesis includes internal recesses on an inside surface of an orifice ring having portions thereof near the recesses tapered to reduce flow resistance and minimize turbulence to improve hemodynamic efficiency of the heart valve prosthesis, to reduce its hemolytic potential, and possibly reduce its thrombogenicity by having no regions of stasis within the recess. The pivot mechanism for the mechanical heart valve prosthesis enables contact between the entire length of tabs of the heart valve leaflets and the sides of the recesses when the leaflets are in both the fully open and fully closed positions. This increases the contact area between the tabs and the recesses, reducing the magnitude of the contact stresses and, therefore, improving the durability of the device.