Abstract: A heart valve prosthesis has a suture ring with a core for form-coupling with the stent of the prosthesis so that the suture ring and the stent are held securely together axially, while the core can rotate relative to the stent. The suture ring has a covering which cooperates with the surface of the stent and is in contact therewith. The degree of contact determines the resistance to relative rotation of the ring and the stent.

Abstract: A vacuum forming apparatus for fixing and shaping animal tissue into the shape of a cardiac valve prosthesis, including a tapered form, with elongated through apertures, suspended in a reservoir of fixative and vacuum means for producing a reduced pressure within the tapered form.

Abstract: A cardiac valve prosthesis comprises an annular frame and a valve sleeve with a plurality of valve flaps which are forced apart by the blood passing through the prosthesis in one direction and which are mutually coapted by blood flow in the opposite direction. The frame of the prosthesis includes a rigid or semi-rigid stent constituted by a tubular body with a ring of apertures and with first and second end edges which, in the implanted position of the prosthesis, are respectively upstream and downstream with respect to the direction of flow of the blood through the prosthesis. Biocompatible textile completely covers the rigid stent: the covering has associated suture stitches some of which extend through the apertures of the said ring to attach the covering to the stent itself.

Abstract: Sheets of incompletely fixed biological tissue comprising portions for defining valve flaps of a cardiac valve prosthesis are mounted on forming means which can separate in a substantially fluid-tight manner the opposite faces of such portions. These opposite faces are subjected to a fluid pressure difference which produces deformation of the portions towards a conformation substantially identical with the conformation of the valve flaps when mounted in the prosthesis. The biological tissue is finally fixed while the portions defining the valve flaps of the prosthesis are maintained in the said conformation. The sheets of biological tissue are then separated from the forming means to be subsequently mounted in the frame of the prosthesis.