Intravascular stent

• US 6,770,088 B1
• Filed: 05/18/2000
• Issued: 08/03/2004
• Est. Priority Date: 04/26/1996
• Status: Expired due to Term

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Jang, G. David
• Primary Examiner(s): PREBILIC, PAUL B
• Application Number:
  US09/574,077
• Time in Patent Office: 1,538 Days
• Field of Search: 606/198, 623/1.13, 623/1.16, 623/1.17, 623/23.7
• US Class Current: 623/1.16
• 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 2/958 Inflatable balloons for placing stents or stent-grafts
• 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 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61F 2250/0018 differing in elasticity, stiffness or compressibility

Abstract

A stent in a non-expanded state has a first and second expansion column, each consisting of a plurality of expansion strut pairs. An expansion strut pair includes a first expansion strut, a second expansion strut and a joining strut that couples the first and second expansion struts at one end. Expansion strut pairs include expansion strut pair first and second corners formed where the joining strut couples the first and second expansion struts. A connecting strut column, formed of a plurality of connecting struts couples the first and second expansion columns. Connecting struts include a proximal section, a distal section and an intermediate section. The proximal section is coupled to the corner of an expansion strut pair of the first expansion column, and the distal section is coupled to the joining strut of an expansion strut pair of the second expansion column intermediate the expansion strut pair first corner and the expansion strut pair second corner.

Claims

1. A stent in a non-expanded state, comprising:

a first expansion column formed of a plurality of first expansion column strut pairs,

a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair,

a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair,

a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair,

a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair,

the first, second, third and fourth joining struts slanted relative to the longitudinal axis of the stent,

a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut

and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut

and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut

and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut

and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut

and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset,

the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a second expansion column formed of a plurality of first expansion column strut pairs,

a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair,

a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair,

a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair,

a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair,

the first, second, third and fourth joining struts slanted relative to the longitudinal axis of the stent,

and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut

and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut

and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut

and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut

and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset,

the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a first connecting strut column formed of a plurality of first connecting struts, each connecting strut of the first connecting strut column including a connecting strut proximal section, a connecting strut distal section and a connecting strut intermediate section, a first connecting strut proximal portion is coupled to the first outer corner of the second expansion strut pair of the first expansion strut column, and a first connecting strut distal section is offset in both a circumferential and a longitudinal direction from the first connecting strut proximal section and coupled to the first joining strut of the first expansion strut pair of the second expansion strut column intermediate the first expansion strut pair first outer corner and the first expansion strut pair second outer corner, and a second connecting strut proximal section is coupled to the first outer corner of the fourth expansion strut pair of the first expansion strut column, and a second connecting strut distal section is offset in both a circumferential and a longitudinal direction from the second connecting strut proximal section and coupled to the third joining strut of the third expansion pair of the second expansion strut column intermediate the third expansion strut pair first outer corner and the third expansion strut pair second outer corner.

2. The stent of claim 1, wherein each connecting strut proximal section has a substantially linear geometry.

3. The stent of claim 2, wherein each connecting strut distal section has a substantially linear geometry.

4. The stent of claim 3, wherein each connecting strut intermediate section has a substantially linear geometry.

5. The stent of claim 3, wherein each connecting strut intermediate section includes a first linear section and second linear section.

6. The stent of claim 5, wherein the first linear section of the first connecting strut intermediate section is shorter than the second linear section of the first connecting strut intermediate section.

7. The stent of claim 5, wherein each of a connecting strut proximal section, distal section, first linear section of the intermediate section and second linear section of the intermediate section have a different longitudinal axis.

8. The stent of claim 5, wherein a first slant angle is formed between the first linear section of the first connecting strut intermediate section and the second linear section of the first connecting strut intermediate section.

9. The stent of claim 8, further including a radius of curvature formed at the first slant angle.

10. The stent of claim 5, wherein a radius of curvature is formed between the first linear section and the second linear section of the first connecting strut intermediate section.

11. The stent of claim 5, wherein a second slant angle is formed between the second linear section of the first connecting strut intermediate section and the distal section of the first connecting strut.

12. The stent of claim 5, wherein a radius of curvature is formed between the second linear section of the first connecting strut intermediate section and the distal section of the first connecting strut.

13. The stent of claim 5, wherein a third slant angle is formed between the proximal section of the first connecting strut and the first linear section of The first connecting strut intermediate section.

14. The stent of claim 5, wherein a radius of curvature is formed between the proximal section of each connecting strut and the first linear section of each connecting strut intermediate section.

15. The stent of claim 1, wherein a ratio of a number of expansion struts in an expansion strut column to a number of connecting struts in a connecting strut column is 2 to 1.

16. The stent of claim 1, wherein the stent includes m first and second expansion columns, n expansion struts per column and n (m−

1)/2 connecting struts.

17. The stent of claim 1, wherein the first and second expansion columns are each unbroken, continuous column structures.

18. The stent of claim 1, wherein one of the first or second expansion column is a broken column structure.

19. The stent of claim 1, further comprising:

a plurality of first expansion columns;

a plurality of second expansion columns; and

a plurality of first connecting strut columns, each first connecting strut column coupling a first expansion column to a second expansion column.

20. The stent of claim 19, wherein the plurality of first expansion columns, the plurality of second expansion columns and the plurality of first connecting strut columns form an elongated structure.

21. The stent of claim 1, wherein the first expansion column, the second expansion column, and the first connecting strut column form a plurality of geometric cells and at least a portion of the plurality are symmetrical geometric cells.

22. The stent of claim 1, wherein the first expansion strut column, the second expansion strut column and the first connecting strut column form asymmetrical geometric configurations.

24. The stent of claim 1, further comprising:

a reenforcement expansion column made of a plurality of reenforcement expansion struts,

wherein each reenforcement expansion strut has a width that is greater than a width of an expansion strut in the first or second expansion columns.

25. The stent of claim 1, wherein the stent has a proximal end with a first reenforcement expansion column and a distal end with a second reenforcement expansion column.

26. The stent of claim 1, wherein the stent has a reenforcement expansion column between a proximal end and a distal end of the stent.

28. The stent of claim 1, wherein a width of tile first connecting strut is equal to or less than a width of the first expansion strut of the first or second expansion columns.

29. The stent of claim 1, wherein a width of a connecting strut of the first connecting strut column is larger than a width of a first expansion strut of the first or second expansion columns.

30. The stent of claim 1, wherein a width of the second expansion stut of the first or second expansion columns is substantially the same as the width of the first expansion strut of the first or second expansion columns.

31. The stent of claim 1, wherein a space between the first and second expansion struts of the first expansion column is equal to a space between the second and third expansion struts of the first expansion column.

32. The stent of claim 1, wherein a space between the first and second expansion struts of the first expansion column is less than a space between the second and third expansion struts of the first expansion column.

33. The stent of claim 1, wherein a space between the first and second expansion struts of the expansion column is larger than a space between the second and third expansion struts of the first expansion column.

23. A stent in a non-expanded state, comprising:

a first expansion column formed of a plurality of first expansion column strut pairs, a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair, a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair, a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair, a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair, a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut, and a first expansion strut pair second corner formed where the first joining strut is coupled to the second expansion strut, and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut, and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut, and a third expansion strut first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset,

the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset, the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a second expansion column formed of a plurality of second expansion column strut pairs, a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair, a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair, a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair, a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair, a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut, and a first expansion strut pair second inner corner and second outer corner formed where the first. joining strut is coupled to the second expansion strut, and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut, and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut, and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut, and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset,

the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a first connecting strut column formed of a plurality of first connecting struts, each connecting strut of the first connecting strut column including a connecting strut proximal section, a connecting strut distal section and a connecting strut intermediate section, a first connecting strut proximal section is coupled to the first outer corner of the second expansion strut pair of the first expansion strut column, and a first connecting strut distal section is offset in both a circumferential and a longitudinal direction from the first Connecting strut proximal section and coupled to the first joining strut of the first expansion strut pair of the second expansion strut column intermediate the first expansion strut pair first outer corner and the first expansion strut pair second outer corner, and a second connecting strut proximal section is coupled to the first outer corner of the fourth expansion strut pair of the first expansion strut column, and a second connecting strut distal section is offset in both a circumferential and a longitudinal direction from the second connecting strut proximal section and coupled to the third joining strut of the third expansion strut pair of the second expansion strut column intermediate the third expansion strut pair first outer corner and the third expansion strut pair second outer corner; and

wherein the connecting struts are asymmetrically shaped.

27. A stent in a non-expanded state, comprising:

a first expansion column formed of a plurality of first expansion column strut pairs, a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair, a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair, a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair, a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair, a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut, and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut, and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut, and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut, and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut, and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset, the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offet, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a second expansion column formed of a plurality of second expansion column strut pairs, a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair, a second expansion strut pair including, a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair, a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair, a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair, a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut, and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut, and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut, and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut, and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut, and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair second inner corner and second outer corner formed which the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset, the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset, all of the joining struts of the second expansion column slanted relative to the longitudinal axis of the stent;

a first connecting strut column formed of a plurality of first connecting struts, each connecting strut of the first connecting strut column including a connecting strut proximal section, a connecting strut distal section and a connecting strut intermediate section, a first connecting strut proximal section is coupled to the first outer corner of the second expansion strut pair of the first expansion strut column, and a first connecting strut distal section is coupled to the first joining strut of the first expansion strut pair of the second expansion strut column intermediate the first expansion strut pair first outer corner and the first expansion strut pair second outer corner, and a second connecting strut proximal section is coupled to the first outer corner of the fourth expansion strut pair of the first expansion strut column, and a second connecting strut distal section is coupled to the third joining strut of the third expansion strut pair of the second expansion strut column intermediate the third expansion strut pair first outer corner and the third expansion strut pair second outer corner;

a third expansion column formed of a plurality of third expansion column strut pairs, a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair, a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair, a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair, a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair, a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut, and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut, and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut, and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut, and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut, and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut, and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset, the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset; and

a second connecting strut column formed of a plurality of second connecting struts, each connecting strut of the second connecting strut column including a connecting strut proximal section, a connecting strut distal section and a connecting strut intermediate section, a first connecting strut proximal section is coupled to the second outer corner of the second expansion strut pair of the second expansion strut column, and a first connecting strut distal section is offset in both a circumferential and a longitudinal direction from the first connecting strut proximal section and coupled to the first joining strut of the first expansion strut pair of the third expansion strut column intermediate the first expansion strut pair first outer corner and the first expansion strut pair second outer corner, and a second connecting strut proximal section is coupled to the second outer corner of the fourth expansion strut pair of the second expansion strut column, and a second connecting strut distal section is offset in both a circumferential and a longitudinal direction from the second connecting strut proximal section and coupled to the third joining strut of the third expansion strut pair of the third expansion strut column intermediate the third expansion strut pair first outer corner and the third expansion strut pair second outer corner.

34. A stent in a non-expanded state, comprising:

a first expansion column formed of a plurality of first expansion column strut pairs,

a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair,

a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair,

a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair,

a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair,

a first expansion strut pair first inner corner and first outer corner formed where the first joining strut is coupled to the first expansion strut

and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut

and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut

and a second expansion strut pair second inner coiner and second outer corner formed where the second joining strut is coupled to the third expansion strut

and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion stut

and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion stut

and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut pair second outer corner being longitudinally and circumferentially offset, the fourth expansion strut pair first inner corner and the fourth expansion strut pair second inner corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a second expansion column formed of a plurality of first expansion column strut pairs,

a first expansion strut pair including a first expansion strut adjacent to a second expansion strut and a first joining strut that couples the first and second expansion struts at a proximal end of the first expansion strut pair,

a second expansion strut pair including a third expansion strut adjacent to the second expansion strut and a second joining strut that couples the second and third expansion struts at a distal end of the second expansion strut pair,

a third expansion strut pair including a fourth expansion strut adjacent to the third expansion strut and a third joining strut that couples the third and fourth expansion struts at a proximal end of the third expansion strut pair,

a fourth expansion strut pair including a fifth expansion strut adjacent to the fourth expansion strut and a fourth joining strut that couples the fourth and fifth expansion struts at a distal end of the fourth expansion strut pair,

and a first expansion strut pair second inner corner and second outer corner formed where the first joining strut is coupled to the second expansion strut

and a second expansion strut pair first inner corner and first outer corner formed where the second joining strut is coupled to the second expansion strut

and a second expansion strut pair second inner corner and second outer corner formed where the second joining strut is coupled to the third expansion strut

and a third expansion strut pair first inner corner and first outer corner formed where the third joining strut is coupled to the third expansion strut

and a third expansion strut pair second inner corner and second outer corner formed where the third joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair first inner corner and first outer corner formed where the fourth joining strut is coupled to the fourth expansion strut

and a fourth expansion strut pair second inner corner and second outer corner formed where the fourth joining strut is coupled to the fifth expansion strut, the second expansion strut pair first inner corner and the second expansion strut pair second inner corner being longitudinally and circumferentially offset, the second expansion strut pair first outer corner and the second expansion strut lair second outer corner being longitudinally and circumferentially offset, the fourth expansion strut pair first corner and the fourth expansion strut pair second corner being longitudinally and circumferentially offset, the fourth expansion strut pair first outer corner and the fourth expansion strut pair second outer corner being longitudinally and circumferentially offset;

a first connecting strut column formed of a plurality of first connecting struts, each connecting strut of the first connecting strut column including a, connecting strut proximal section, a connecting strut distal section and a connecting strut intermediate section, a first connecting strut proximal section is coupled to the first outer corner of the second expansion strut pair of the first expansion strut column, and a first connecting strut distal section is offset in both a circumferential and a longitudinal direction from the first connecting strut proximal section and coupled to the first joining strut of the first expansion strut pair of the second expansion strut column intermediate the first expansion strut pair first outer corner and the first expansion strut pair second outer corner, and a second connecting strut proximal section is coupled to the first outer corner of the fourth expansion strut pair of the first expansion strut column, and a second connecting strut distal section is offset in both a circumferential and a longitudinal direction from the second connecting strut proximal section and coupled to the third joining strut of the third expansion pair of the second expansion strut column intermediate the third expansion strut pair first outer corner and the third expansion strut pair second outer corner.