Methods of conditioning sheet bioprosthetic tissue

• US 9,492,230 B2
• Filed: 09/17/2012
• Issued: 11/15/2016
• Est. Priority Date: 03/23/2010
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Schneider, Ralph, Tian, Bin, Dove, Jeffrey S., Cohen, Jeff, Jankovic, Ivan, Migliazza, John F., Wright, Gregory A., Young, James, Campbell, Louis A.
• Primary Examiner(s): Woznicki, Jacqueline
• Application Number:
  US13/621,680
• Publication Number:
  US 20130110097A1
• Time in Patent Office: 1,520 Days
• Field of Search: 623/2.13
• US Class Current: 1/1
• CPC Class Codes: A61B 18/20 using laser
• CPC Class Codes: A61F 2/02 Prostheses implantable into the body closure means for urethra or rectum or for artificial body openings therefor A61F2/0004
• CPC Class Codes: A61F 2/24 Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body
• CPC Class Codes: A61F 2/2409 Support rings therefor, e.g. for connecting valves to tissue annuloplasty rings A61F2/2442
• CPC Class Codes: A61F 2/2415 Manufacturing methods
• CPC Class Codes: A61F 2/2418 Scaffolds therefor, e.g. support stents
• CPC Class Codes: A61F 2002/30324 differing in thickness
• CPC Class Codes: A61F 2250/0036 differing in thickness
• CPC Class Codes: A61L 2300/60 characterised by a special physical form
• CPC Class Codes: A61L 2430/20 for reconstruction of the heart, e.g. heart valves
• CPC Class Codes: A61L 27/3604 characterised by the human or animal origin of the biological material, e.g. hair, fascia, fish scales, silk, shellac, pericardium, pleura, renal tissue, amniotic membrane, parenchymal tissue, fetal tissue, muscle tissue, fat tissue, enamel
• CPC Class Codes: A61L 27/3625 Vascular tissue, e.g. heart valves
• CPC Class Codes: A61L 27/3691 characterised by physical conditions of the treatment, e.g. applying a compressive force to the composition, pressure cycles, ultrasonic/sonication or microwave treatment, lyophilisation
• CPC Class Codes: A61L 27/507 for artificial blood vessels apparatus for applying cells on a blood vessel prosthesis A61F2/062
• CPC Class Codes: B65B 55/18 by liquids or gases B65B55/14 takes precedence
• CPC Class Codes: B65B 63/02 for compressing or compacting articles or materials prior to wrapping or insertion in containers or receptacles

Abstract

Methods for the conditioning of bioprosthetic material employ bovine pericardial membrane. A laser directed at the fibrous surface of the membrane and moved relative thereto reduces the thickness of the membrane to a specific uniform thickness and smoothes the surface. The wavelength, power and pulse rate of the laser are selected which will smooth the fibrous surface as well as ablate the surface to the appropriate thickness. Alternatively, a dermatome is used to remove a layer of material from the fibrous surface of the membrane. Thinning may also employ compression. Stepwise compression with cross-linking to stabilize the membrane is used to avoid damaging the membrane through inelastic compression. Rather, the membrane is bound in the elastic compressed state through addition cross-linking. The foregoing several thinning techniques may be employed together to achieve strong thin membranes.

Claims

1. A method for preparing bioprosthetic tissue membrane material, comprising:

removing at least a portion of material from a tissue membrane having a fibrous side and a smooth side, wherein the at least a portion of material is removed from the fibrous side of the tissue membrane by ablating the fibrous side of the tissue membrane with a very short pulse duration laser to reduce thickness non-uniformity of the tissue membrane.

2. The method of claim 1, wherein the tissue membrane is bovine pericardial membrane.

3. The method of claim 1, further comprising, prior to the removing, cross-linking the tissue membrane, treating the tissue membrane with a capping agent and a reducing agent, and subjecting the tissue membrane to a glycerin-based treatment solution.

4. The method of claim 1, wherein the tissue membrane before the removing has a thickness of 250-700 microns, and the removing reduces the thickness of at least the portion of the tissue membrane to less than 250 microns.

5. The method of claim 1, wherein the removing includes ablating the fibrous side of the tissue membrane with an ultra-short-pulsed laser in the Femtosecond range.

6. The method of claim 5, wherein the laser utilized has a 1550 nm wavelength.

7. The method of claim 1, wherein the laser is characterized as having:

a pulse width of 650 fs; and

a wavelength of 1550 nm.

8. The method of claim 1, further comprising:

cross-linking the tissue membrane; and

forming the tissue membrane to have an arcuate cusp edge and a free edge opposite the cusp edge to produce a heart valve leaflet;

wherein the cross-linking and the forming are performed before the removing.

9. The method of claim 8, wherein removing material reduces a thickness of a central region of the leaflet to a greater degree than a thickness of the cusp edge.

10. The method of claim 9, wherein the tissue membrane is bovine pericardial membrane, and after removing material the thickness of the cusp edge is between 250-700 microns, and the thickness of the central region is less than 250 microns.

11. The method of claim 8, wherein removing material reduces a thickness of a central region of the leaflet to a greater degree than a thickness of the free edge.

12. The method of claim 9, wherein removing material reduces the thickness of the central region between generally uniform width strips that extend radially from a center of the free edge to the cusp edge.

13. The method of claim 9, wherein transitions between reduced thickness portions and adjacent thicker portions of the leaflet are gradual.

14. The method of claim 8, wherein removing material reduces a thickness of the entire heart valve leaflet to below 300 microns.

15. The method of claim 8, further comprising subjecting the membrane to a glycerin-based treatment solution prior to removing material and after cross-linking.

16. The method of claim 15, further comprising treating the membrane after the glycerin-based treatment solution with a capping agent and a reducing agent.

17. The method of claim 8, wherein removing material includes ablating with an ultra-short-pulsed laser in the Femtosecond range.

18. The method of claim 17, wherein the laser utilized has a 1550 nm wavelength.

19. The method of claim 1, further comprising:

cross-linking a bioprosthetic tissue membrane;

subjecting the tissue membrane to a glycerin-based treatment solution after the cross-linking; and

forming the tissue membrane to have a peripheral edge region, a free edge opposite the peripheral edge region, and a central region surrounded by the peripheral edge region and free edge to produce at least one heart valve leaflet;

wherein the cross-linking, subjecting and forming are performed before the removing; and

wherein after the removing, attaching a plurality of the heart valve leaflets to a structural stent by connecting the peripheral edge regions of each leaflet to the structural stent to produce a bioprosthetic heart valve.

20. The method of claim 19, wherein the peripheral edge region of each leaflet defines an arcuate cusp edge opposite the free edge, wherein removing material reduces a thickness of the central region of the leaflet to a greater degree than a thickness of the cusp edge, and a portion of the peripheral edge region that is thicker along an adjacent reduced thickness central region extends in a generally uniform width strip along the cusp edge.

21. The method of claim 19, wherein the structural stent is configured to be radially collapsible to a collapsed state for introduction into a body on a delivery catheter and radially expandable to an expanded state for implanting the bioprosthetic heart valve at a desired location in the body.

22. The method of claim 21, wherein the peripheral edge region of each leaflet defines an arcuate cusp edge opposite the free edge, wherein the bioprosthetic heart valve includes three of the leaflets connected to each other at adjacent cusp edges in a tricuspid arrangement to form a leaflet assembly, and the portions of the peripheral edge regions in each leaflet that are thicker than the adjacent reduced thickness central regions collectively define a ribbon that extends along a lower edge portion of an inside surface of the leaflet assembly and connects to the structural stent with sutures.

23. The method of claim 19, wherein the step of removing material reduces a thickness of the entire heart valve leaflet to below 300 microns.

24. The method of claim 1, further comprising exposing the fibrous side of the tissue membrane in a planar configuration prior to the removing.

25. The method of claim 24, wherein the laser comprises a focal length at or near a top of the fibrous side.

26. The method of claim 1, further comprising exposing the fibrous side of the tissue membrane placed on a supporting surface of a forming mold prior to the removing, wherein the supporting surface comprises at least one portion that is lower than the remaining portion of the supporting surface;

and wherein the removing is performed while the tissue membrane is on the supporting surface of the forming mold.

27. A bioprosthethic implant comprising the bioprosthetic tissue membrane material produced in accordance with claim 1.

28. A bioprosthetic heart valve comprising the heart valve leaflet produced in accordance with claim 8.

29. A heart valve produced in accordance with claim 19.