Adjustable, flexible mitral and tricuspid annuloplasty rings having internal drawstrings that emerge from the rings on the annular faces so that the drawstring knots are out of the bloodstream, the drawstrings being contained in clearly marked channels, the mitral ring having a curved semi-flexible stiffener...http://www.google.es/patents/US5201880?utm_source=gb-gplus-sharePatente US5201880 - Mitral and tricuspid annuloplasty rings
