Methods and apparatus for manufacture of valve flaps for cardiac valve prostheses

Claim 2

A process for the manufacture of valve flaps (10) for cardiac valve prosthesis (1) from sheets of biological tissue (90), in which the said flaps (10) are mounted in a support frame (2) and in which sheets of incompletely fixed biological tissue (90), including portions which can define the said valve flaps (10), are subjected to final fixation whilst the said portions are maintained in a conformation substantially identical to the conformation of the valve flaps (10) when mounted in the prosthesis (1), characterised by the fact that it comprises the operations of: - providing forming means (29) for the said sheets of biological tissue (90) capable of separating from each other in a substantially fluid-tight manner the opposite faces of said valve flap defining portions, - applying the said sheets of biological tissue (90) to the said forming means (29), - generating a fluid pressure difference between the opposite separated faces of the said portions to produce the deformation of the portions towards the said conformation substantially identical to the conformation of the valve flaps (10) when mounted in the prosthesis (1), - effecting the final fixation of the biological tissue, and, - separating the said sheets of biological tissue (90) from the said forming means for subsequent mounting in the support frame (2).

Claim 3

A process according to Claim 1,characterised by the fact that the final fixation of the biological tissue is effected by means of a fixation fluid (11) brought into contact with at least one of the opposite faces of the said portions of biological tissue.

Claim 4

A process according to Claim 2, characterised by the fact that the said pressure difference is generated by pressurising the fixation fluid (L)and bringing the pressurised fixation fluid(L)into contact with one of the opposite faces of the said portions of biological tissue.

Claim 5

A process according to Claim 3, characterised by the fact that the said portions of biological tissue are substantially immersed in the fixation fluid(L)and by the fact that the said pressure difference is established between the bodies of fixation fluid which are in contact with the opposite faces of the said portions.

Claim 6

A process according to Claim 4, characterised by the fact that the magnitude of the said pressure difference and the length of time for fixation of the biological tissue are selected in such a way as to effect a substantial diffusion of the fixation liquid (L)through the said deformed portion of biological tissue.

Claim 7

A process for the manufacture of valve flaps for cardiac prostheses (1) comprising a frame (3 - 8)capable of being traversed by a flow of blood and a sleeve (9) of biological tissue , with a plurality of valve flaps (10) anchored to the frame (3 - 8) along respective crescent shaped edges (10a) and provided with free edges (10b) projecting inwardly of the frame (3 - 8) and able to be separated by blood flowing through the prosthesis (1) in one direction and to prevent the flow of blood in the opposite direction by moving to closely matching positions under the pressure exerted by the blood itself, characterised by the fact that it comprises the operations of: - providing a sleeve-forming element (29) of substantially tubular form, the wall (30) of which has angularly adjacent apertures (34) corresponding in number to the number of valve flaps (10) of the sleeve (9) and separated from one another by shaped wall elements (35) extending in an axial direction with respect to the forming element (29); the said apertures (34) having corresponding end edges (34a) the shape of which reproduces the shape of the said crescent shaped edges (10a) of the valve flaps (10) of the sleeve (9), - sealingly fitting a tubular sheath (90) of incompletely fixed biological tissue over the said forming element (30), - establishing between the interior of the forming element (29) and the exterior of the said element (29) a pressure difference such that the portions of the sheath (9 0 ) of biological tissue facing the said apertures (34) of the forming element (29) are pressed inwardly of the said cavity in an arrangement in which the portions of the sheath (90) deformed by the effect of such pressure difference converge radially into the forming element (29) in partial matching conditions and each has at least one crescent shaped edge (10a), - effecting the final fixation of the biological tissue of the sheath (90) whilst maintaining the said pressure difference between the interior cavity of the forming element (29) and the exterior of the element (29) itself, such that each of the said portions assumes, in a substantially stable manner, by virtue of the such final fixation, the deformed conformation achieved by the effect of the said pressure difference, - separating the finally fixed biological tissue of the sheath (90) along a line (91) joining the ends of the crescent shaped edges (10a) of the said portions of the stably deformed sheath (90) to create, in each of such portions, a free edge defining the free edge (10b) of one of the valve flaps (10) of the sleeve (9).

Claim 8

A process for the manufacture of valve flaps for cardiac prostheses (1) comprising a frame (3 - 8)capable of being traversed by a flow of blood and a sleeve (9) of biological tissue , with a plurality of valve flaps (10) anchored to the frame (3 - 8) along respective crescent shaped edges (10a) and provided with free edges (10b) projecting inwardly of the frame (3 - 8) and able to be separated by blood flowing through the prosthesis (1) in one direction and to prevent the flow of blood in the opposite direction by moving to closely matching positions under the pressure exerted by the blood itself, characterised by the fact that it comprises the operations of: - providing a sleeve-forming element (29) of substantially tubular form, the wall (30) of which has angularly adjacent apertures (34) corresponding in number to the number of valve flaps (10) of the sleeve (9) and separated from one another by shaped wall elements (35) extending in an axial direction with respect to the forming element (29); the said apertures (34) having corresponding end edges (34a) the shape of which reproduces the shape of the said crescent shaped edges (10a) of the valve flaps (10) of the sleeve (9), - sealingly fitting a tubular sheath (90) of incompletely fixed biological tissue over the said forming element (30), - establishing between the interior of the forming element (29) and the exterior of the said element (29) a pressure difference such that the portions of the sheath (9 0 ) of biological tissue facing the said apertures (34) of the forming element (29) are pressed inwardly of the said cavity in an arrangement in which the portions of the sheath (90) deformed by the effect of such pressure difference converge radially into the forming element (29) in partial matching conditions and each has at least one crescent shaped edge (10a), - effecting the final fixation of the biological tissue of the sheath (90) whilst maintaining the said pressure difference between the interior cavity of the forming element (29) and the exterior of the element (29) itself, such that each of the said portions assumes, in a substantially stable manner, by virtue of the such final fixation, the deformed conformation achieved by the effect of the said pressure difference, - separating the finally fixed biological tissue of the sheath (90) along a line (91) joining the ends of the crescent shaped edges (10a) of the said portions of the stably deformed sheath (90) to create, in each of such portions, a free edge defining the free edge (10b) of one of the valve flaps (10) of the sleeve (9).

Claim 9

A process according to Claim 5, characterised by the fact that the said sheath (90) is obtained starting from a sheet of biological tissue wound into a tube by bringing two opposite edges of such sheet together and connecting them by stitching the said edges.

Claim 10

A process according to Claim 5 or Claim 7, characterised by the fact that the said tubular sheath (90) is fixed to the forming element (29) by means of resilient sealing rings (37) fitted over the forming element (29) on opposite sides of the said apertures (34).

Claim 11

Apparatus for the manufacture of valve flaps for cardiac prostheses comprising a frame (3 - 8) which can be traversed by a flow of blood and a sleeve (9) of biological tissue with a plurality of valve flaps (10) anchored to the frame (3 - 8) along respective crescent shaped edges (10a) and provided with free edges (10b) projecting inwardly of the frame (3 - 8), able to be separated by blood flowing through the prosthesis (1) in one direction and to prevent the flow of blood in the opposite direction by moving to closely matching positions under the pressure exerted by the blood itself, characterised by the fact that it comprises: - a reservoir (21) which can be filled with a fluid (L) for the fixation of the biological tissue, - at least one forming element (29) for the said sleeve (9), projecting into the said reservoir (21) in a position immersed in the said fixation liquid (L), the said forming element (29) being of substantially tubular form with a peripheral wall (30) traversed by adjacent apertures, equal in number to the number of valve flaps (10) of the sleeve (9), separated from one another by shaped wall elements (35) extending in an axial direction with respect to the forming element (29); the said apertures having corresponding end edges (35) the shape of which reproduces the shape of the said crescent shaped edges (10a) of the valve flaps (10) of the sleeve, and - means (26, 27 129) for establishing a pressure difference between the fixation fluid(L)within the reservoir (21) and the interior cavity of the said forming element (29).

Claim 12

Apparatus for the manufacture of valve flaps for cardiac prostheses comprising a frame (3 - 8) which can be traversed by a flow of blood and a sleeve (9) of biological tissue with a plurality of valve flaps (10) anchored to the frame (3 - 8) along respective crescent shaped edges (10a) and provided with free edges (10b) projecting inwardly of the frame (3 - 8), able to be separated by blood flowing through the prosthesis (1) in one direction and to prevent the flow of blood in the opposite direction by moving to closely matching positions under the pressure exerted by the blood itself, characterised by the fact that it comprises: - a reservoir (21) which can be filled with a fluid (L) for the fixation of the biological tissue, - at least one forming element (29) for the said sleeve (9), projecting into the said reservoir (21) in a position immersed in the said fixation liquid (L), the said forming element (29) being of substantially tubular form with a peripheral wall (30) traversed by adjacent apertures, equal in number to the number of valve flaps (10) of the sleeve (9), separated from one another by shaped wall elements (35) extending in an axial direction with respect to the forming element (29); the said apertures having corresponding end edges (35) the shape of which reproduces the shape of the said crescent shaped edges (10a) of the valve flaps (10) of the sleeve, and - means (26, 27 129) for establishing a pressure difference between the fixation fluid(L)within the reservoir (21) and the interior cavity of the said forming element (29).

Claim 13

Apparatus according to Claim 9, characterised by the fact that the said shaped wall elements (3 5 ) are of generally flattened form, orientated in a radial direction with respect to the forming element (29) and are delimited, on the radially outer side, by a surface (35d) which is substantially free of discontinuities.

Claim 14

Apparatus according to Claim 9, characterised by the fact that the said forming element (29) has, at least in the region in which the said apertures (34) are provided, a frusto-conical shape.

Claim 15

Apparatus according to Claim 9, characterised by the fact that the reservoir (21) can receive a partial filling of fixation liquid(L)and by the fact that the reservoir (21) has associated therewith a source (26,27) of gas under pressure selectively adjustable to introduce gas under controlled pressure into the interior (25) of the reservoir (21) situated above the free surface of the fixation liquid(L).

Claim 16

Apparatus according to Claim 9, characterised by the fact that it includes a vacuum generator (129) which can be connected to the interior cavity of each said forming element (29).

Claim 17

Apparatus according to Claim 9, characterised by the fact that the said reservoir (21) includes a cover (21b) having holes (28) each of which forms a mounting seat for an associated forming element (29), each of said holes (28) being associated with a fluid-tight closure member (32) which is transparent and allows observation of the interior cavity of the associated said forming element (29).

Claim 18

Apparatus according to Claim 13 and Claim 15, characterised by the fact that the said cover (21b) is provided with ducts (28a) opening into the said holes (28) and which can put the said vacuum generator (129) into communication with the interior cavity of each said forming element (29).