Systems and methods for assembling components of a fabric-covered prosthetic heart valve

• US 20060276889A1
• Filed: 06/07/2005
• Published: 12/07/2006
• Est. Priority Date: 06/07/2005
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Chambers, Freeman G., Zysman, Lawrence J.
• Granted Patent: US 7,739,971 B2
• Time in Patent Office: Days
• US Class Current: 623/2.170
• CPC Class Codes: A61F 2/2415 Manufacturing methods
• CPC Class Codes: Y10T 29/49405 Valve or choke making
• CPC Class Codes: Y10T 29/53552 Valve applying or removing

Abstract

A system and method for assembling a prosthetic heart valve, including a procedure for tightly wrapping fabric around a heart valve support stent. The support stent typically includes alternating cusps and commissures that create a highly contoured undulating outflow edge. The system includes a mandrel for retaining tension without manual assistance in a tubular length of fabric wrapped over the support stent. The mandrel may include an inner clamping mechanism for holding the first end of the fabric tube, a pedestal tube on which the support stent rests and through which the fabric tube passes, and an outer clamping mechanism for holding the free end of the fabric tube. The inner and outer clamping mechanisms include discrete clamps spaced apart 120° from each other that pull the fabric only in the cusps of the support stent. The inner clamping mechanism, outer clamping mechanism, and pedestal are relatively axially movable. Once the fabric is retained over the support stent, the mandrel may be placed in a chuck of a sewing machine system for automatically forming the seam. A small shuttle with bobbin thread reciprocates within a channel inside of the support stent and cooperates with the sewing machine needle to form a lock-stitch in the fabric tube. The mechanization of the fabric covering procedure greatly enhances manufacturing throughput and reduces ergonomic strain on workers.

Claims

1. A system for assembling components of a flexible leaflet prosthetic heart valve having a generally tubular fabric-covered support stent defining a central axis, the system comprising:

a mandrel for retaining tension without manual assistance in a tubular length of fabric wrapped over an outflow end of a heart valve support stent, wherein the outflow end includes an undulating contour and the mandrel is adapted to retain tension in the tubular length of fabric so that it conforms to the undulating contour; and

a means for forming a seam in the tubular length of fabric adjacent the inflow end of the support stent to enclose the support stent.

2. The system of claim 1, wherein the undulating contour of the outflow end includes multiple cusps curved toward an axial inflow end alternating with multiple commissures projecting toward an axial outflow end, and the mandrel includes separate clamps for the fabric corresponding to the stent cusps.

3. The system of claim 2, wherein there are three inflow cusps and three outflow commissures alternating around a periphery of the support stent, and wherein the mandrel clamps the fabric beyond an axial inflow end of the stent in peripheral locations corresponding to the cusps.

4. The system of claim 3, wherein the mandrel includes an outer clamping mechanism comprising three clamp members oriented 120°

apart in each of which is adapted to clamp a section of fabric.

5. The system of claim 4, wherein the mandrel includes an inner clamping mechanism comprising two disks between which one end of the tubular length of fabric may be clamped.

6. The system of claim 5, further including a pedestal tube that fits on the mandrel and holds the support stent, the pedestal tube, outer clamping mechanism, and inner clamping mechanism all being relatively axially movable.

7. The system of claim 1, further including a pedestal tube that fits on the mandrel and holds the support stent, the pedestal tube having a pedestal adjacent one end that is contoured to orient the support stent in a particular rotational position.

8. The system of claim 1, wherein the means for forming a seam comprises an electric sewing machine.

9. A system for assembling a prosthetic heart valve, comprising:

two components of a prosthetic heart valve, one of which is a generally tubular prosthetic heart valve support stent having an outflow end with an undulating contour, and the other of which is a tubular length of fabric; and

a mandrel having at least one clamp for holding and maintaining the tubular length of fabric wrapped around the outflow end in a taut fashion such that the tubular length of fabric conforms to the undulating contour.

10. The system of claim 9, wherein:

the undulating contour of the support stent includes multiple cusps curved toward an axial inflow end alternating with multiple commissures projecting toward an axial outflow end;

the mandrel is disposed beyond the inflow end of the support stent;

the system further including;

multiple commissure clamps arranged to hold the fabric-covered support stent commissures.

11. The system of claim 10, further including:

an electric sewing machine having a needle, the electric sewing machine including a shaft for rotating the commissure clamps, wherein the needle is positioned to form a seam in the fabric covering at the inflow end of the support stent, and wherein the sewing machine includes a chuck for receiving and rotating the mandrel about the stent axis in conjunction with the commissure clamps.

12. The system of claim 11, wherein the sewing machine is adapted to axially displace the commissure clamps as it rotates, and the chuck is adapted to axially displace the mandrel in conjunction with the commissure clamps.

13. A method of assembling a prosthetic heart valve, comprising:

providing a generally tubular support stent that includes multiple cusps curved toward an axial inflow end alternating with multiple commissures projecting toward an axial outflow end, the support stent having an undulating outflow edge;

wrapping a tubular length of fabric over the support stent;

retaining tension in the tubular length of fabric using mechanization such that the fabric is held tautly along the undulating outflow edge; and

forming a seam in the tubular length of fabric adjacent the inflow edge of the support stent.

14. The method of claim 13, further including:

providing a mechanized support stent holding mandrel;

retaining tension using the mandrel in the tubular length of fabric such that the fabric is held tautly along the undulating outflow edge; and

15. The method of claim 14, wherein the mandrel further includes an inner clamping mechanism, an outer clamping mechanism, and a pedestal tube, and wherein the method further includes:

positioning the support stent on the pedestal tube;

securing opposite ends of the tubular length of fabric with the inner and outer clamping mechanisms, respectively; and

tensioning the tubular length of fabric around the support stent by relative movement of both the inner and outer clamping mechanisms with respect to the pedestal tube.

16. The method of claim 15, further including tightening the tubular length of fabric around the support stent by relatively axially displacing the inner and outer clamping mechanisms with respect to the pedestal tube.

17. The method of claim 16, wherein the inner and outer clamping mechanisms each include discrete clamps spaced apart 120°

from each other that directly tension the fabric only at the cusps of the support stent.

18. The method of claim 16, further including holding the fabric-wrapped commissures of the support stent with a plurality of commissure clamps and separating the pedestal tube from the support stent by relatively axially displacing the pedestal tube with respect to the commissure clamps.

19. The method of claim 18, wherein the support stent has an undulating inflow edge, the method further including simultaneously axially displacing and rotating the commissure clamps and the mandrel while forming the seam with a needle of a sewing machine system passing through the length of tubular fabric adjacent the inflow edge.

20. A method of assembling a prosthetic heart valve, comprising:

providing a generally tubular heart valve support stent that includes a first edge and an axially-opposite second edge;

wrapping a tubular length of fabric over the first edge of the support stent such that two free ends of the tubular length of fabric continue past the second edge;

retaining tension in the tubular length of fabric such that the fabric is held tautly along the first edge; and

mapping the peripheral contour of the second edge of the support stent with an imaging system; and

forming a seam in the tubular length of fabric closely adjacent the second edge of the support stent using an automated sewing system having a needle whose position relative to the second edge is responsive to the mapped contour of the second edge.

21. The method of claim 20, wherein the second edge of the support stent is an inflow edge that has an undulating contour, the method further including simultaneously axially displacing the support stent while forming the seam with the needle of the automated sewing system.

22. The method of claim 21, wherein the first edge of the support stent is an outflow edge that includes multiple cusps curved toward an axial inflow end alternating with multiple commissures projecting toward an axial outflow end, and wherein the step of retaining tension comprises retaining tension without manual assistance so that the tubular length of fabric conforms to the cusps and commissures of the outflow edge.

23. The method of claim 20, wherein the step of forming the seam comprises positioning the needle of the automated sewing system within about 0.030 inches (0.762 mm) of the second edge during the step of forming the seam.

24. The method of claim 20, wherein the imaging system comprises:

an ultraviolet light and a camera.