Compressed tissue for heart valve leaflets

• US 7,141,064 B2
• Filed: 05/08/2002
• Issued: 11/28/2006
• Est. Priority Date: 05/08/2002
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Khanna, Rajesh A., Scott, Michael J.
• Primary Examiner(s): Pellegrino, Brian E.
• Application Number:
  US10/141,145
• Publication Number:
  US 20030212454A1
• Time in Patent Office: 1,665 Days
• Field of Search: 623/1.26, 623/2.12, 623/2.13, 623/901, 623/908, 623/922, 600/36, 264/316, 264/494, 264/219, 264/239, 264/195, 264/DIG.42, 156/245, 8 9/411
• US Class Current: 623/2.13
• CPC Class Codes: A61F 2/2412 with soft flexible valve members, e.g. tissue valves shaped like natural valves check valves with flexible valve members in general F16K15/14
• CPC Class Codes: A61F 2/2415 Manufacturing methods
• CPC Class Codes: A61F 2/2418 Scaffolds therefor, e.g. support stents
• CPC Class Codes: A61F 2/2475 Venous valves
• CPC Class Codes: A61F 2/92 Stents in the form of a rolled-up sheet expanding after insertion into the vessel , e.g. with a spiral shape in cross-section
• CPC Class Codes: A61F 2220/0075 sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: Y10S 623/918 Heart

Abstract

A process and system for compressing bioprosthetic tissue for use in medical implants. The process involves placing the tissue between two compressive surfaces and applying a force to reduce any nonuniformity of thickness in the tissue, while at the same time reduce the overall thickness. One particularly useful application is the compression of bioprosthetic sheet during the preparation of heart valve leaflets. Bovine pericardium may be compressed to reduce its thickness by about 50%, and then formed into heart valve leaflets. The thinned leaflets have substantially the same absolute strength as those made from uncompressed tissue, and are particular desirable for use in minimally invasive valves which must be compressed into a small profile. The thin tissue enables a reduction in the overall size of the minimally invasive heart valve for delivery. For instance, rolled MIS valves may be reduced in size to as small as 20 mm in diameter. Desirably, a cross-linking step is combined with the compression step to fix the reduced thickness of the tissue. One apparatus may include porous compression substrates through which a cross-linking solution may diffuse so as to perform the fixation and compression simultaneously.

Claims

1. A method of manufacturing an improved leaflet for a minimally invasive heart valve, comprising:

providing a substantially flat sheet formed entirely of pericardial tissue and having a starting thickness, the sheet having opposite first and second surfaces;

placing the sheet of pericardial tissue on a first substrate such that the first surface of the pericardial tissue contacts the first substrate;

displacing a second substrate such that it contacts the second surface of the pericardial tissue;

applying a compressive force to the sheet of pericardial tissue to reduce the thickness of the pericardial tissue by at least about 10% to a reduced thickness without substantially reducing an absolute tensile strength of the pericardial tissue; and

cutting at least one heart valve leaflet from the compressed sheet of pericardial tissue, the reduced thickness leaflet being configured for use with a minimally invasive heart valve.

2. The method of claim 1, wherein the step of applying comprises:

applying a compressive force of at least about 250 pounds for a period of at least about 30 minute.

3. The method of claim 1, wherein the starting thickness is between about 0.30–

0.46 mm, and wherein the resulting thickness is less than about 0.23 mm.

4. The method of claim 3, wherein the step of applying a compressive force to the sheet of pericardial tissue reduces its starting thickness by between 50–

60%.

5. The method of claim 1, further including placing at least one shim between the first and second substrates to limit the reduction in thickness of the sheet of pericardial tissue.