STEEP-TAPER FLARED STENTS AND APPARATUS AND METHODS FOR DELIVERING THEM

• US 20070073376A1
• Filed: 08/22/2006
• Published: 03/29/2007
• Est. Priority Date: 08/22/2005
• Status: Active Grant

• Current Assignee: Incept LLC
• Original Assignee: Incept LLC
• Inventors: Khosravi, Farhad, Dreher, James, Krolik, Jeffrey, Kim, Eliot
• Granted Patent: US 8,702,777 B2
• Time in Patent Office: Days
• US Class Current: 623/1.110
• 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 2002/30322 differing in surface structures
• CPC Class Codes: A61F 2002/821 Ostial stents
• 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 2230/005 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 2250/0018 differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2250/0026 differing in surface structures
• CPC Class Codes: A61F 2250/0039 differing in diameter
• CPC Class Codes: A61M 25/1002 characterised by balloon shape A61M25/1006, A61M25/1009 take precedence

Abstract

A stent includes a first flaring portion including first and second sets of cells that flare outwardly when the stent is expanded from a contracted to a flared condition, and a second main portion connected to the first flaring portion. During use, the stent is introduced into a main vessel in the contracted condition and positioned with the first portion adjacent an ostium. The first portion is flared, causing first struts of the first set of cells to move from an axial towards a radial and partial circumferential orientation and causing second struts of the second set of cells to move from an axial towards a radial orientation. The second portion resists expansion when the first portion is flared. The stent is expanded further such that the second portion expands within the branch body lumen, and the first and second struts move towards a more circumferential orientation.

Claims

1. A stent comprising a tubular member including first and second ends defining a longitudinal axis therebetween and a plurality of cells disposed between the first and second ends, the tubular member being expandable from a contracted condition to an enlarged condition, the stent comprising:

a first flaring portion configured to flare outwardly when the stent is expanded from the contracted condition to the enlarged condition; and

a second main portion adjacent the first portion, the second portion comprising a proximal main portion adjacent the first portion and a distal main portion, the proximal main portion having a radial strength greater than the distal main portion.

2. The stent of claim 1, wherein the first flaring portion has a radial strength less than the distal main portion.

3. The stent of claim 1, wherein each of the proximal main portion and the distal main portion comprises axial segments connected by curved segments to define one or more zigzag bands, at least one of the curved segments and the axial segments having a greater stiffness in the proximal main portion than in the distal main portion.

4. The stent of claim 1, wherein the curved segments and the axial segments in the proximal main portion have a width greater than in the distal main portion to provide the greater stiffness.

5. The stent of claim 1, wherein the first flaring portion comprises:

a first set of cells disposed at the first end, the first set of cells comprising first axial segments in the contracted condition; and

a second set of cells disposed adjacent the first set of cells, the second set of cells comprising second axial segments in the contracted condition,

wherein the first axial segments transition to extend at least partially circumferentially in the expanded configuration, and the second axial segments transition to extend at least partially radially outwardly in the expanded configuration.

6. The stent of claim 5, wherein a ratio of a diameter of the first flaring portion to the second main portion in the enlarged condition is between about 1.1 and 1.8.

7. The stent of claim 1, wherein the first flaring portion is connected to the second main portion by a plurality of connectors comprising curvilinear segments having a thickness and a width, at least one of the thickness and the width being thinner than segments comprising the first flaring portion.

8. The stent of claim 1, wherein the proximal main portion comprises at least two annular bands and the distal main portion comprises a plurality of annular bands.

9. A stent comprising a tubular member including first and second ends defining a longitudinal axis therebetween and a plurality of cells disposed between the first and second ends, the tubular member being expandable from a contracted condition to an enlarged condition through an intermediate condition, the stent comprising:

a first flaring portion configured to flare outwardly when the stent is expanded from the contracted condition to the intermediate condition, the first flaring portion comprising a first set of cells at the first end and a second set of cells adjacent the first set of cells, the second set of cells comprising segments extending substantially axially in the contracted condition;

a second main portion adjacent the first flaring portion, the second main portion comprising a proximal main portion connected to the second set of cells of the first flaring portion by a plurality of connectors, the connectors being relatively flexible such that the axial segments of the second set of cells assume a generally radially outward orientation in the intermediate condition, the proximal main portion having a stiffness greater than the second set of cells;

wherein the first set of cells comprise a plurality of segments extending substantially axially in the contracted condition, the axial segments of the first set of cells assuming a generally circumferential orientation in the enlarged condition.

10. The stent of claim 9, wherein a ratio of a diameter of the first end portion to the second end in the intermediate condition is between about two and five.

11. The stent of claim 10, wherein a ratio of a diameter of the first end portion to the second end in the enlarged condition is between about 1.1 and 1.8.

12. An apparatus for treating an ostium communicating between a main body lumen and a branch body lumen, comprising:

an elongate member comprising a proximal end, a distal end sized for introduction into the main body lumen and the branch body lumen;

a first expandable member on the distal end, the first expandable member being expandable from a collapsed configuration to a substantially spherical expanded configuration;

a second expandable member on the distal end adjacent the first expandable member, the second expandable member being expandable from a collapsed configuration to a substantially cylindrical expanded configuration; and

a stent on the distal end over the first and second expandable members, the stent comprising a first flaring portion overlying a portion of the first expandable member, and a second main portion comprising a distal main portion overlying the second expandable member, and a proximal main portion connecting the first flaring portion to the distal main portion, the proximal main portion overlying a transition between the first and second expandable members.

wherein, when the first expandable member is expanded, the first flaring portion of the stent is expanded to a flared condition, and when the second expandable member is expanded, the second main portion is expanded radially outwardly and the first flaring portion is further expanded radially outwardly.

13. The apparatus of claim 12, wherein the proximal main portion has a greater stiffness than the first flaring portion such that the proximal main portion resists expansion when the first expandable member is expanded.

14. The apparatus of claim 12, wherein the proximal main portion has a greater radial strength than the distal main portion.

15. The apparatus of claim 12, wherein the first expandable member comprises a semi-compliant or substantially compliant balloon.

16. The apparatus of claim 15, wherein the second expandable member comprises a balloon that is less compliant than the first expandable member.

17. The apparatus of claim 15, wherein the second expandable member comprises a substantially non-compliant balloon.

18. The apparatus of claim 17, wherein the first and second expandable members require respective inflation pressures to expand to the expanded configuration, and wherein the inflation pressure of the first expandable member is less than the inflation pressure of the second expandable member.

19. The apparatus of claim 12, wherein the first expandable member is expandable independently of the second expandable member using an inflation pressure that is less than an inflation pressure necessary to expand the second expandable member.

20. The apparatus of claim 12, wherein the first flaring portion of the stent comprises:

a first set of cells disposed at the first end;

a second set of cells disposed adjacent the first set of cells, and

a plurality of flexible connectors connecting the second set of cells to the second portion of the stent,

wherein the second set of cells comprises struts connected to curved segments, the curved segments having a lower yield strength than the struts.

21. The apparatus of claim 20, wherein the struts are directed from a generally axial orientation towards a generally radially outward orientation when the first expandable member is expanded.

22. The apparatus of claim 20, wherein the struts are directed from the generally radially outward orientation in the flared condition towards a circumferential orientation when the second expandable member is expanded.

23. The apparatus of claim 20, the first set of cells comprising struts that extend substantially axially when the stent is in a contracted condition, the first end portion flaring such that the struts are directed towards a circumferential orientation in the flared condition.

24. The apparatus of claim 20, wherein the connectors comprise curvilinear segments having a thickness and a width, at least one of the thickness and the width being thinner than segments comprising the first end portion.

25. The apparatus of claim 12, further comprising a source of inflation media communicating with an interior of the first expandable member for delivering first and second predetermined volumes into the first expandable member to partially and fully expand the first expandable member, respectively.

26. The apparatus of claim 25, wherein the source of inflation media comprises a syringe comprising a barrel including inflation media therein and a plunger, the barrel comprising first and second markers such that, when the plunger is depressed successively to the first and second markers, the first and second predetermined volumes are delivered into the interior of the first expandable member, respectively.

27. A method for expanding a stent, comprising:

providing a stent on one or more expandable members, the stent comprising first and second ends, a first flaring portion including a first set of cells at the first end and a second set of cells adjacent the first set of cells, and a second main portion connected to the first flaring portion;

expanding an expandable member to flare the first flaring portion, thereby causing first struts of the first set of cells to move from a substantially axial orientation towards a radial and partial circumferential orientation and causing second struts of the second set of cells to move from a substantially axial orientation towards a radial orientation;

expanding an expandable member to expand the second main portion to an enlarged condition, thereby causing the first and second struts to move towards a more circumferential orientation.

28. The method of claim 27, wherein the second main portion comprises a distal main portion and a proximal main portion connecting the first flaring portion to the distal main portion, the proximal main portion comprising a stiffness greater than the first flaring portion such that the proximal main portion resists expansion when the first flaring portion is flared.

29. A method for delivering a stent within an ostium communicating between a main body lumen and a branch body lumen, the stent comprising first and second ends, a first flaring portion including a first set of cells at the first end and a second set of cells adjacent the first set of cells, and a second main portion, the second main portion comprising a distal main portion and a proximal main portion connecting the distal main portion to the first flaring portion, the method comprising:

introducing the stent into the main body lumen with the stent in a contracted condition;

flaring the first flaring portion, the proximal main portion resisting expansion when the first flaring portion is flared;

expanding the stent such that the second main portion expands within the branch body lumen, and the first and second struts move towards a more circumferential orientation.

30. The method of claim 29, wherein a pressure required to flare the first flaring portion is substantially less than a pressure required to expand the second main portion.

31. The method of claim 29, wherein the proximal main portion has a radial strength greater than the distal main portion, the proximal main portion being expanded within the ostium and the distal main portion being expanded within the branch body lumen.

32. The method of claim 29, wherein, when the first flaring portion is flared, first struts of the first set of cells move from a substantially axial orientation towards a radial and partial circumferential orientation and second struts of the second set of cells move from a substantially axial orientation towards a radial orientation.

33. The method of claim 32, wherein the first and second struts move towards a more circumferential orientation when the stent is expanded such that the second main portion expands.