BEND-CAPABLE STENT PROSTHESIS

• US 20090204201A1
• Filed: 05/18/2007
• Published: 08/13/2009
• Est. Priority Date: 05/18/2006
• Status: Active Grant

• Current Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Original Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Inventors: Wack, Thilo
• Granted Patent: US 8,574,286 B2
• Time in Patent Office: Days
• US Class Current: 623/1.160
• CPC Class Codes: A61F 2/844 folded prior to deployment
• 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 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/825 having longitudinal struts
• CPC Class Codes: A61F 2002/91516 the meander having a change in frequency along the band
• CPC Class Codes: A61F 2002/91525 within the whole structure different bands showing different meander characteristics, e.g. frequency or amplitude
• CPC Class Codes: A61F 2002/91541 Adjacent bands are arranged out of phase
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2210/0014 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2230/0054 V-shaped

Abstract

Normally, when stents are bent, inside the body of the stented patient, there is head-to-head collision between facing V-points on the inside of the bend. However, by alternating between two whole numbers the number of struts between successive connectors around the circumference of each of the stenting rings, the V-points are caused to veer circumferentially in opposite directions as they approach each other on the inside of the bend, so allowing them to pass by each other without collision, thereby allowing in the same stent both close packing of the ring stack, and an enhanced ability to tolerate severe bending, after placement in the body.

Claims

1. A prosthesis that is expandable from a radially compact delivery disposition to a radially expanded stenting disposition, and is composed of a stack of zig-zag stenting rings of struts that end in points of inflection spaced around the circumference of a stenting lumen that is itself on a longitudinal axis of the stent, each of the points of inflection being located at one or the other of the two axial ends of each ring, with adjacent rings A, B, C in the stack being connected by straight connectors linking selected facing pairs of points of inflection of each two adjacent rings, circumferentially intervening pairs of facing points of inflection being unconnected, and with progress from strut to strut via the points of inflection, around the full circumference of one of the stenting rings B, namely one that is located axially between adjacent rings A and C in the stack, the connector ends encountered during such progress connect ring B alternately, first to ring A, then to ring C, then to ring A again, and so on:

characterised in that

the connectors are parallel to the longitudinal axis and are shorter than said strut length;

the pairs of unconnected points of inflection remain facing, in the radially expanded disposition, for as long as the longitudinal axis remains a straight line;

the number of struts in ring B that lie between successive said connector ends that join ring B alternately to ring A, then ring C, is a whole number that alternates between two different values; and

the connectors are so short that, when the stent functioning as a stent is caused to bend, such that the longitudinal axis becomes arcuate, the facing pairs of unconnected points of inflection that are on the inside of the bend eventually pass axially past each other, side by side, circumferentially spaced from each other, rather than impacting on each other, head to head.

2. The prosthesis as claimed in claim 1, wherein the number of struts “

N”

of ring B lying between any two adjacent A-B connector portions is such that N/2 is an even number, so that the B-C connectors cannot be placed circumferentially on ring B half way between any two of the A-B connectors.

3. The prosthesis as claimed in claim 1, wherein the number of struts “

N”

of ring B lying between any two adjacent A-B connector portions is such that N/2 is an odd number and N is more than 10.

4. The prosthesis as claimed in claim 1, wherein the lattice points of the connectors together exhibit a helical path that is coaxial with the longitudinal axis of the prosthesis.

5. The prosthesis as claimed in claim 1, wherein each of the stenting rings is composed of struts that have all the same length, such that each of the points of inflection in such a ring lie in one of two circles transverse to the longitudinal axis of the prosthesis.

6. The prosthesis as claimed in claim 1, wherein all the struts in rings A, B and C have the same cross-section and length.

7. The prosthesis as claimed in claim 1, comprising a shape memory alloy.

8. The prosthesis as claimed in claim 1, which undergoes plastic deformation expansion to its stenting disposition.

9. The prosthesis as claimed in claim 1, which is a peripheral vascular stent.

10. The prosthesis as claimed in claim 1, which is a biliary stent.

11. The prosthesis as claimed in claim 1, wherein the connectors in rings A, B, C have a length which is less than 1 mm.

12. The prosthesis as claimed in claim 11, which connector length is not more than 0.8 mm.

13. The prosthesis as claimed in claim 12, which connector length is less than 0.6 mm.

14. The prosthesis as claimed in claim 1, with a strut length of more than 1.25 mm within the rings A, B, C.

15. The prosthesis as claimed in claim 14, with a strut length in a range of from 1.3 mm to 2.2 mm

16. The prosthesis as claimed in claim 15, with a strut length in a range of from 1.4 mm to 2.0 mm.

17. The prosthesis as claimed in claim 1, with 32 struts in each of the zig-zag rings A, B, C.

18. The prosthesis as claimed in claim 1, with 4 evenly spaced connectors between ring A and ring B.