The surgical technique adapts the valve-in-valve approach for mitral replacement in degenerated mitral prostheses to failing native mitral valves. The MValve Dock is designed to provide a structural platform within the mitral annulus so that the Lotus THV can be implanted in a secure fashion in the mitral annulus. The investigational device anchors to the mitral annulus commissures, sparing the native valve leaflets and sub annular apparatus. This study is designed to treat subjects with moderate-to-severe MR who are not deemed candidates for mitral valve surgery.