Helical stent having improved flexibility and expandability

• US 20050159807A1
• Filed: 03/08/2005
• Published: 07/21/2005
• Est. Priority Date: 08/30/2002
• Status: Active Grant

• Current Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Original Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Inventors: Kratsch, Peter K., Bales, Thomas O., Perry, Kenneth E.
• Granted Patent: US 8,512,391 B2
• Time in Patent Office: Days
• US Class Current: 623/1.150
• CPC Class Codes: A61F 2/88 the wire-like elements formed as helical or spiral coils forming a net-like or mesh-like structure A61F2/90
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91508 the meander having a difference in amplitude along the band
• 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 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2002/91583 by a bridge, whereby at least one of its ends is connected along the length of a strut between two consecutive apices within a band
• CPC Class Codes: A61F 2250/0036 differing in thickness
• CPC Class Codes: A61F 2250/0037 differing in height or in length
• CPC Class Codes: A61F 2250/0098 radio-opaque, e.g. radio-opaque markers

Abstract

A stent includes a central portion of helically wound undulations formed of struts, cylindrical end portions, and transition zones between the helical portion and the cylindrical portions. According to a first aspect of the invention, the torsional flexibility of the stent is maximized by having bridges connecting adjacent winding be interrupted by the maximum possible number of undulations. In a preferred design, each winding includes nineteen undulations around the circumference, bridges are provided every five undulations. According to a second aspect of the invention, uniform opening of the transition zone is achieved by altering the width, and thereby the flexibility, of a series of struts in accordance with their lengths. Specifically, the long transition zone struts are made wider.

Claims

1. A stent for insertion into a vessel of a patient, the stent comprising:

a central portion comprised of a plurality of helical circumferential windings, each of said windings including a plurality of undulations, wherein each undulation comprises a pair of struts connected to each other,

bridges extending between undulations on adjacent windings to connect adjacent helical windings to each other,

wherein a same number of struts is traversed from any one bridge to a next bridge on each of said windings when traveling in either a right-handed or left-handed direction along each of said windings.

2. The stent of claim 1, wherein:

said pair of struts of each undulation is connected by a loop.

3. The stent of claim 2, wherein:

said bridges extend between loops located one and one-half pitches away.

4. The stent of claim 1, wherein:

each circumferential winding of said central portion of said stent includes sixteen to twenty undulations.

5. The stent of claim 4, wherein:

each circumferential winding of said central portion of said stent includes eighteen to nineteen undulations.

6. The stent of claim 1, wherein:

each circumeferential winding includes three to five bridges extending therefrom.

7. The stent of claim 1, wherein:

each of said bridges in said central portion extends in a same direction in a cylindrical plane of said stent.

8. The stent of claim 7, wherein:

each of said bridges extends longitudinally crosswise between adjacent windings.

9. The stent of claim 1, wherein the stent is a self-expanding stent.

10. The stent of claim 1, wherein the stent comprises a laser cut tube.

11. The stent of claim 1, wherein the stent is made from a superelastic material.

12. The stent of claim 1 further comprising:

cylindrical end portions, and

a transition zone between said central portion and each of said end portions, said transition zone including a plurality of transition undulations having struts that progressively increase in length,

wherein a relatively longer strut of said transition undulations has a relatively wider width than a relatively shorter strut of said transition undulations.

13. A stent for insertion into a vessel of a patient, comprising:

a central portion comprised of;

a plurality of helical circumferential windings, each of said windings including a plurality of undulations,

bridges extending between said adjacent windings,

wherein, for at least one of said windings, for any given number n of undulations on said winding and any given number b of bridges connected to said winding;

where n is not equal to b, a maximum number of undulations is provided between said bridges.

14. The stent of claim 13, wherein:

said undulations on adjacent windings are interdigitated.

15. A stent for insertion into a vessel of a patient, comprising:

a central portion comprised of a plurality of helical circumferential windings, each of said windings including a plurality of undulations, with each said undulation being defined by two adjacent struts connected together,

at least one cylindrical end portion at an end of said central portion, and

transition zones between said central portion and each of said cylindrical end portions, said transition zone including a plurality of transition undulations having struts that progressively increase in length,

wherein a relatively longer strut of said transition undulations has a relatively wider width than a relatively shorter strut of said transition undulations

16. The stent of claim 15, wherein:

said longest strut of said transition undulations is 1.19 to 1.99 times wider than said shortest strut of said transition undulations.

17. The stent of claim 15, wherein:

said longest strut of said transition undulations is approximately 1.59 times wider than said shortest strut of said transition undulations.

18. The stent according to claim 15, wherein:

said struts of said central portion are all of a common length and width.

19. The stent according to claim 15, wherein:

said common length of said struts of said central portion is shorter than a shortest length of said struts of said transition undulations, and

said common width of said struts of said central portion is narrower than a narrowest width of said struts of said transition undulations.