Helical stent having improved flexibility and expandability

• US 20040044401A1
• Filed: 08/30/2002
• Published: 03/04/2004
• Est. Priority Date: 08/30/2002
• Status: Active Grant

• Current Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Original Assignee: Edwards Lifesciences AG (Edwards Lifesciences Corporation)
• Inventors: Kratsch, Peter K., Bales, Thomas O., Perry, Kenneth E.
• Granted Patent: US 6,878,162 B2
• Time in Patent Office: Days
• US Class Current: 623/1.22
• 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, comprising:

a tubular member having a first smaller diameter for insertion into the vessel, and a second larger diameter for deployment within the vessel,

said tubular member including a central portion comprised of a plurality of helical circumferential windings separated by a helical space, each of said windings including a plurality of undulations, with each said undulation being defined by two adjacent struts and a loop connecting the struts,

wherein adjacent windings are connected with a plurality of bridges, said bridges extending across said helical space between said adjacent winding and connected to said loops of a plurality of said undulations, and

further 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. A stent according to claim 1, wherein:

said loops of said undulations on adjacent windings are interdigitated.

3. A stent according to claim 2, wherein:

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

4. A stent according to claim 1, wherein:

said central portion of said stent includes sixteen to twenty undulations.

5. A stent according to claim 4, wherein:

said central portion of said stent includes eighteen to nineteen undulations.

6. A stent according to claim 1, wherein:

each winding includes three to five bridges extending therefrom.

7. A stent according to claim 1, wherein:

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

8. A stent according to claim 7, wherein:

each of said bridges extends longitudinally crosswise across said helical space.

9. A stent according to claim 1, wherein:

said tubular member is self-expanding from said first diameter to said second diameter.

10. A stent according to claim 1, wherein:

said tubular member is a laser cut tube.

11. A stent according to claim 1, wherein:

said tubular member is made from a superelastic material.

12. A stent according to claim 1, wherein:

said tubular member includes 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 tubular member having a first smaller diameter for insertion into the vessel, and a second larger diameter for deployment within the vessel,

said tubular member including a central portion comprised of a plurality of helical circumferential windings separated by a helical space, each of said windings including a plurality of undulations, with each said undulation being defined by two adjacent struts and a loop connecting the struts,

wherein adjacent windings are connected with a plurality of bridges, said bridges extending across said helical space between said adjacent winding and connected to said loops of a plurality of said undulations,

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≠

b, a maximum number of undulations is provided between said bridges.

14. A stent according to claim 13, wherein:

said undulations on adjacent windings are interdigitated.

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

a tubular member having a first smaller diameter for insertion into the vessel, and a second larger diameter for deployment within the vessel, and defining a longitudinal axis, said tubular member including

a central portion comprised of a plurality of helical circumferential windings separated by a helical space, each of said windings including a plurality of undulations, with each said undulation being defined by two adjacent struts and a loop connecting said struts,

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

a 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. A stent according to claim 15, wherein:

said tubular member has a longitudinal axis and adjacent struts of said transition zone are defined as a pair of struts, said transition zone having a plurality of said pairs, and

when said stent has said first smaller diameter, said struts of said central portion and said transition zone all extend substantially parallel to said longitudinal axis, and

when said stent has said second larger diameter, an angle is defined between said struts of each said pair of struts, and said angle is substantially the same for each said pair of struts.

17. A stent according to 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.

18. A stent according to claim 15, wherein:

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

19. A stent according to claim 15, wherein:

said at least one cylindrical end portion is two cylindrical end portions.

20. A stent according to claim 15, wherein:

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

21. A 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.