Design and assembly of fenestrated stent grafts

• US 20070142896A1
• Filed: 08/18/2006
• Published: 06/21/2007
• Est. Priority Date: 08/18/2005
• Status: Active Grant

• Current Assignee: Cook Medical Incorporated (Cook Group Incorporated)
• Original Assignee: Cook Incorporated (Cook Group Incorporated), William A. Cook Australia Pty. Ltd (Cook Group Incorporated)
• Inventors: Lawrence-Brown, Michael, Hartley, David, Anderson, John
• Granted Patent: US 8,172,895 B2
• Time in Patent Office: Days
• US Class Current: 623/1.130
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/89 the wire-like elements comprising two or more adjacent rings flexibly connected by separate members
• CPC Class Codes: A61F 2002/061 provided with means for allowing access to secondary lumens
• CPC Class Codes: A61F 2002/065 Y-shaped blood vessels
• CPC Class Codes: A61F 2002/075 the stent being loosely attached to the graft material, e.g. by stitching
• CPC Class Codes: A61F 2002/9505 having retaining means other than an outer sleeve, e.g. male-female connector between stent and instrument
• CPC Class Codes: A61F 2002/9511 the retaining means being filaments or wires
• CPC Class Codes: A61F 2230/005 Rosette-shaped, e.g. star-shaped
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61F 2230/0067 conical
• CPC Class Codes: A61F 2250/0039 differing in diameter

Abstract

A method of sizing of a stent graft (20) including placement of fenestrations (30, 32) to ensure access to side branch vessels (13, 15) through the fenestrations when the stent graft is introduced into a body vessel and an assembly method for a stent graft including temporary diameter reduction arrangements to enable partial release of a stent graft to assist with positioning of fenestrations with respect to side branch vessels. The method includes spacing the fenestrations to be the same circumferential distance as the side branch vessels irrespective of the diameter of the stent graft.

Claims

1. A method of pre-operative sizing of a stent graft with at least two fenestrations for placement into a body vessel having an inner wall with side branch vessels and the stent graft intended for access to the side branch vessels through the fenestrations, the method comprising the steps of;

a) determining the internal diameter of the body vessel at the level of the side branch vessels,

b) assessing the angular position of the of each of the side branch vessels from a selected datum position on the vessel,

c) converting the angular position to a circumferential distance along the inner wall of the vessel from the selected vessel datum to each side branch vessel for each of the branch vessels,

d) selecting a diameter of stent graft which is 10% to 20% greater than the determined diameter of the vessel, and

e) positioning fenestrations on the stent graft such that each is the converted distance calculated in step c) from a stent datum position on the stent.

2. A method as in claim 1 wherein the selected datum position on the vessel is the anterior most point in the vessel and the stent datum position is the anterior most position in the stent.

3. A method as in claim 1 wherein the internal diameter of the body vessel and the angular position of the of each of the side branches are determined with the use of narrow slice, contrast enhanced computer tomography.

4. A method as in claim 1 wherein the step of assessing the angular position of the of each of the side branches from a selected datum position on the vessel, comprises defining the angular position as a clock face with the datum position being 12 o'"'"'clock and the position of the of each of the side branches being in terms of hours on the clock face.

5. A method as in claim 1 wherein the step of assessing the angular position of the of each of the side branches from a selected datum position on the vessel, comprises defining the angular position as degrees either side of the datum position.

6. A method as in claim 1 further comprising the step of temporarily reducing the diameter of the stent graft at least at the level of the fenestrations at a position substantially diametrically opposite to the stent datum position.

7. A method as in claim 1 wherein the step of temporarily reducing the diameter comprises applying diameter reducing ties.

8. A method as in claim 7 wherein the step of applying diameter reducing ties comprises the steps of;

a) stitching a release wire longitudinally along the stent graft;

b) looping a flexible thread around the release wire and extending one end of the flexible thread laterally around the circumference of the stent graft to a position a selected distance from the release wire;

c) engaging the flexible thread into the graft material, and

d) drawing the ends of the thread together and tying ends of the thread, whereby the selected distance is reduced thereby reducing the overall diameter of the stent graft.

9. A method as in claim 7 wherein the selected distance is reduced by from 50 to 75%.

10. A method as in claim 8 comprising the step of extending a circumferential thread in each direction from the release wire.

11. A method as in claim 8 further comprising the steps of;

e) passing a second flexible thread around the release wire or the first flexible thread and extending the second flexible thread laterally around the circumference of the stent graft in the opposite direction to the first flexible thread to a position a selected distance from the release wire;

f) engaging the second flexible thread into the graft material, and

g) drawing the ends of the second thread together and tying ends of the thread, whereby the selected distance is reduced thereby reducing the overall diameter of the stent graft.

12. A method as in claim 7 wherein the step of applying diameter reducing ties comprises applying a plurality of diameter reducing ties to respective stents along the length of the stent graft.

13. A method as in claim 8 wherein the stents are zig-zag stents comprising struts and bends therebetween and the engagement of the flexible thread into the graft material includes the engagement of the thread around a strut of the self expanding stent.

14. A stent graft prepared by the method of claim 1.

15. A stent graft prepared by the method of claim 7.

16. A stent graft for placement in a body vessel, the body vessel having a measured diameter at the level of side branches of the vessel and the side branches being spaced circumferentially on an inner wall of the vessel by a measured distances from a vessel datum point, the stent graft comprising a tubular body of a biocompatible graft material and at least two fenestrations in the tubular body, the tubular body having a dimeter of between 10 to 20% greater than the measured diameter of the branch vessel in the region of the fenestrations, the fenestrations being spaced apart circumferentially around the tubular body from a selected graft datum point by the measured distance, whereby when the stent graft is introduced in to the vessel the fenestration can be aligned with the side branches.

17. A stent graft as in claim 16 wherein the vessel datum point is an anterior point on the vessel and the graft datum point is the anterior most point on the stent graft.

18. A stent graft as in claim 16 further comprising a plurality of diameter reducing ties temporarily reducing the diameter, the diameter reducing ties being substantially diametrically opposed to the graft datum point.

19. A stent graft as in claim 16 further comprising a temporary diameter reduction constraint arrangement at a position substantially diametrically opposed to the graft datum point, the constraint arrangement comprising at least one release wire extending longitudinally along the tubular body and at least one circumferential thread engaged around the release wire and a portion of the stent graft circumferentially spaced a selected distance away from the release wire and drawn tight and tied to reduce the circumference and hence the overall diameter of the stent graft.