A prosthetic device for treating a mitral valve includes a prosthetic insert member insertable between leaflets of mitral valve. The insert member has an elongated cross-sectional profile for conforming to gap between leaflets of a mitral valve. The device also includes an anchoring member for attachment to heart tissue for maintaining the insert member in the mitral valve. The insert member includes a valve that permits one-way blood flow therethrough. An anchoring member secures the prosthetic insert member to a heart wall.