Flexible expandable stent

• US 6,635,084 B2
• Filed: 10/09/2001
• Issued: 10/21/2003
• Est. Priority Date: 03/17/1994
• Status: Expired due to Fees

• Current Assignee: Medinol Limited (Medinol USA Incorporated)
• Original Assignee: Medinol Limited (Medinol USA Incorporated)
• Inventors: Pinchasik, Gregory, Israel, Henry Marshall
• Primary Examiner(s): Thaler, Michael H.
• Application Number:
  US09/971,616
• Publication Number:
  US 20020010506A1
• Time in Patent Office: 742 Days
• Field of Search: 623/1.15, 623/1.16, 623/1.17, 606/198
• US Class Current: 623/1.17
• CPC Class Codes: A61F 2/856 Single tubular stent with a side portal passage
• 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 2002/91541 Adjacent bands are arranged out of phase
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped

Abstract

A stent for implanting in the body to hold open a blood vessel includes cells with facing loops and the curved flexible links disposed and adapted to cooperate so that, when unexpended, the stent can flex as it is moved through curved blood vessels to a site where it is to be expanded and so that, when the stent is expanded in a curved vessel, at that site, as compared to each other, cells on the outside of the curve are open in length, but narrow in width as compared to cells on the inside of the curve which are short in length but increased in width to result in a more constant stent cell area between the inside and the outside of the curve than would otherwise occur causing the stent, when coated with a medicine, to apply a more even dose to the inside wall of the lumen, avoiding the possibility that a toxic dose is supplied at one area while a less than effective dose is applied to another area.

Claims

1. A stent for implanting in the body to hold open a blood vessel, comprising:

a. a body-compatible metal mesh defining a tube having a plurality of longitudinally adjacent contiguous cells, each of the cells comprising one pair of longitudinally facing loops, each longitudinally facing loop having a generally curved apex and having portions with a substantial longitudinal component extending from said apex, said portions forming walls of the cells, wherein at least some of said portions are also walls of longitudinally adjacent cells, the pair of longitudinally facing loops generally opposite to and facing one another, each of the facing loops adapted to open further upon radial expansion of the stent which tends to foreshorten the stent longitudinally,

b. each of the cells further comprising a pair of members that include flexible curved portions, which members are disposed between the adjacent pair of facing loops and integral therewith to complete each of the cells, the pair of members made of a metal such that, upon curvature of the stent, the members will bend to facilitate flexing of the stent along the longitudinal axis and will, upon expansion of the stent, bend to substantially offset foreshortening along the longitudinal axis, and

c. said pair of facing loops and said curved flexible links disposed and adapted to cooperate so that the tube, when unexpanded, can flex as it is moved through curved blood vessels to a site where it is to be expanded and so that, when the stent is expanded in a curved vessel cells on the outside of the curve become longer in the longitudinal direction, but narrower in width as compared to cells on the inside of the curve.

2. A stent according to claim 1 wherein on the outside of the curve, the flexible curved portions are more open and the facing loops are more closed as compared to the inside of the curve, where the flexible curved portions are more closed and the facing loops are more open.

3. A stent according to claim 1 wherein a self-correction, which occurs when cells on the outside of the curve become longer in length, but narrower in width as compared to cells on the inside of the curve, which are shorter in length but increased in width, results in a more constant density of stent element area between the inside and the outside of the curve than would otherwise occur.

4. A stent according to claim 1 wherein a self-correction, which occurs when cells on the outside of the curve become longer in length, but narrower in width as compared to cells on the inside of the curve, which are shorter in length but increased in width, results in a more constant stent cell area between the inside and the outside of the curve than would otherwise occur.

5. A stent according to claim 3 wherein said stent is coated with a medicine and said more constant density results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

6. A stent according to claim 4 wherein said stent is coated with a medicine and said more constant stent cell area results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

7. The stent of claim 1, positioned on a balloon which upon expansion causes the stent to expand to hold open the blood vessel.

8. The expanded stent of claim 1, in which the expanded stent has approximately the same longitudinal length as the stent had prior to expansion.

9. A balloon-expandable stent defining a longitudinal aperture, said stent comprising

a. a plurality of flexible cells, each of said flexible cells comprising:

i. a first member having a longitudinal component having a first end and a second end;

ii. a second member having a longitudinal component having a first end and a second end;

iii. a third member having a longitudinal component having a first end and a second end;

iv. a fourth member having a longitudinal component having a first end and a second end;

v. a first loop defining a first angle disposed between said first end of said first member and said first end of said second member;

vi. a second loop defining a second angle disposed between said second end of said third member and said second end of said fourth member, and disposed generally opposite to said first loop so that said first angle and said second angle open toward each other;

vii. a first flexible compensating member having a first end and a second end disposed between said first member and said third member, said first end of said first flexible compensating member coupled to said second end of said first member and said second end of said first flexible compensating member coupled to said first end of said third member, said first and said second ends disposed a variable longitudinal distance from each other;

viii. a second flexible compensating member having a first end and a second end disposed between said second member and said fourth member, said first end of said second flexible compensating member coupled to said second end of said second member and said second end of said second flexible compensating member coupled to said first end of said fourth member, said first and said second ends disposed a variable longitudinal distance from each other, said first and said second flexible compensating member differentially extendable or compressible when said stent is bent;

ix. each of at least two members of said first, second, third and fourth members in each of said cells also being a first, second, third or fourth member of a longitudinally adjacent flexible cell; and

x. said first, said second, said third, and said fourth members and said first and said second loops, and said first and said second flexible compensating member disposed so that as said stent is balloon-expanded from a delivery diameter to a deployment diameter the distance between said first and said second flexible compensating member increases and the longitudinal component of said first, second, third and fourth members decreases while said first and said second loops remain generally opposite to one another, the ends of said first and said second flexible compensating member open so as to increase said variable longitudinal distance between said first and said second ends of said first flexible compensating member and so as to increase said variable longitudinal distance between said first and said second ends of said second flexible compensating member so as to compensate for the decreasing of the longitudinal component of said first, second, third, and fourth members and substantially lessen the foreshortening of said stent upon its expansion; and

b. said first and second loops and said flexible compensating member disposed and adapted to cooperate so that the tube, when unexpanded, can flex as it is moved through curved blood vessels to a site where it is to be expanded and so that, when the stent is expanded in a curved vessel, cells on the outside of the curve become longer in the longitudinal direction, but narrower in the circumferential direction as compared to cells on the inside of the curve.

10. A stent according to claim 9 wherein on the outside of the curve, the flexible compensating members become more open and the first and second loops become less open, and on the inside of the curve, the flexible compensating members become less open and the first and second loops become more open.

11. A stent according to claim 9 wherein a self-correction, which occurs when cells on the outside of the curve become more open in length, but more narrow in width and cells on the inside of the curve shorten in length but increase in width, results in a more constant density of stent element area between the inside and the outside of the curve than would otherwise occur.

12. A stent according to claim 11 wherein said stent is coated with a medicine and said more constant stent cell area results in a more even dose veing applied to the inside wall of the lumen, lowering the probabilitythe a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

13. A stent according to claim 9 wherein a self-correction, which occurs when cells on the outside of the curve become more open in length, but more narrow in width and cells on the inside of the curve shorten in length but increase in width, results in a more constant stent cell area between the inside and the outside of the curve than would otherwise occur.

14. A stent according to claim 13 wherein said stent is coated with a medicine and said more constant density of stent element area results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

15. A balloon-expandable stent, comprising:

a. at least two rows of longitudinally adjacent flexible cells disposed about the circumference of the stent, each of said cells having a first longitudinal end and a second longitudinal end and an upper end and a lower end, each of said cells comprising;

i. a first pair of members connected by an area of inflection generally disposed at said first longitudinal end of each of said cells;

ii. a second pair of members connected by an area of inflection generally disposed at said second longitudinal end of each of said cells;

iii. a first flexible compensating member disposed between said first and second pair of members at said upper end of each of said cells; and

iv. a second flexible compensating member disposed between said first and second pair of members at said lower end of each of said cells,

b. each member in at least one of said first pair and said second pair of one flexible cell also being a member of said first pair or second pair of a longitudinally adjacent flexible cell,

c. wherein upon bending of the stent the flexible compensating members on the outside of the bend lengthen in the longitudinal direction and the flexible compensating members on the inside of the bend shorten in the longitudinal direction,

d. wherein upon expansion of the stent by a balloon from a delivery diameter to a deployment diameter, the flexible compensating members lengthen in the longitudinal direction to compensate for the tendency of the stent to foreshorten, and

e. wherein, when the stent is expanded in a curved lumen, on the outside of the bend, the first and second pairs of members come closer together in the circumferential direction, as compared to the first and second members on the inside of the bend, where the first and second pairs of members become more separated in the circumferential direction.

16. A stent according to claim 15 wherein a self-correction which occurs when the first and second pairs of members come closer together in the circumferential direction on the outside and the first and second pairs of members separate in the circumferential direction on the inside compensates respectively for a shortening and lengthening of the flexible compensating members to result in a more constant density of stent element area between the inside and the outside of the curve than would otherwise occur.

17. A stent according to claim 16 wherein said stent is coated with a medicine and said more constant density of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

18. A stent according to claim 15 wherein a self-correction which occurs when the first and second pairs of members come closer together in the circumferential direction on the outside and the first and second pairs of members separate in the circumferential direction on the inside compensates respectively for a shortening and lengthening of the flexible compensating members to result in a more constant stent cell area between the inside and the outside of the curve than would otherwise occur.

19. A stent according to claim 18, wherein said stent is coated with a medicine and said more constant area of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

20. A flexible, balloon-expandable stent having a longitudinal axis, comprising:

a. a plurality of flexible cells, each of said flexible cells comprising;

i. a first pair of members connected by an area of inflection defining a right-facing loop;

ii. a second pair of members connected by an area of inflection defining a left-facing loop that faces the right-facing loop;

iii. a first flexible link coupling the top of said first pair of members to the top of said second pair of members; and

iv. a second flexible link coupling the bottom of said first pair of members to the bottom of said second pair of members,

b. each member in at least one of said first pair and said second pair of one flexible cell also being a member of said first pair or second pair of a longitudinally adjacent flexible cell,

c. wherein said flexible cells are adapted so that said stent prior to expansion is bendable in substantially any direction without affecting the structural or functional integrity of said stent,

d. wherein said flexible cells are adapted so that upon the expansion of said stent by a balloon from a delivery diameter to a deployment diameter, said flexible links lengthen in the longitudinal direction to compensate for the tendency of said stent to foreshorten,

e. wherein said flexible cells are further adapted to impart radial strength to said stent in an amount sufficient to support a lumen when said stent is expanded, and

f. wherein said right and left facing loops and said flexible links are disposed and adapted to cooperate so that the stent, when unexpanded, can flex as it is moved through curved blood vessels to a site where it is to be expanded and so that, when the stent is expanded in a curved vessel cells on the outside of the curve become more open in length, but narrower in width, as compared to cells on the inside of the curve which become shorter in length but increased in width.

21. A stent according to claim 20, wherein on the outside of the curve, the curved flexible links become more open and the loops more closed, and on the inside of the curve, the flexible links become more closed and the loops more open.

22. A stent according to claim 20 wherein a self-correction, which occurs when cells on the outside of the curve open in length, but narrow in width and cells on the inside of the curve shorten in length but thicken in width, results in a more constant density of stent element area between the inside and the outside of the curve than would otherwise occur.

23. A stent according to claim 22 wherein said stent is coated with a medicine and said more constant density of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

24. A stent according to claim 20 wherein a self-correction, which occurs when cells on the outside of the curve open in length, but narrow in width and cells on the inside of the curve shorten in length but thicken in width, results in a more constant stent cell area between the inside and the outside of the curve than would otherwise occur.

25. A stent according to claim 24, wherein said stent is coated with a medicine and said more constant area of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

26. An expandable stent for supporting a vessel, wherein in the expanded and deployed state, the stent consists of:

a. first meander patterns having loops, the first meander patterns being longitudinally spaced from each other and having axes extending in a first direction; and

b. second meander patterns having loops, the second meander patterns having axes extending in a second direction, different than the first direction,

c. wherein the first and second meander patterns are interconnected to form a tubular structure;

d. wherein the first meander patterns are connected to the second meander patterns so as to leave at least one loop of each of the second meander patterns in the space between each pair of adjacent first meander patterns;

e. wherein the second meander patterns are connected to the first meander patterns so as to leave no more than two loops of each of the first meander patterns between each pair of adjacent second meander patterns; and

f. wherein said first and second meander patterns are adapted to cooperate so that, when the expanded stent is in a curved vessel, on the outside of the curve, a circumferential compression and horizontal expansion of the loops in said first meander pattern substantially compensates for a horizontal expansion and circumferential compression of the loops in said second meander pattern and, on the inside of the curve, vice versa.

27. A stent according to claim 26, wherein on the outside of the curve, the loops in said second meander pattern become more open and the loops in the first meander pattern more closed, and on the inside of the curve, the loops in said second meander pattern become more closed and the loops in the first meander pattern more open.

28. A stent according to claim 26 wherein the compensation maintains a density of stent element area which is more constant on the inside and on the outside of the curve than it would without the compensation.

29. A stent according to claim 28 wherein said stent is coated with a medicine and said more constant density of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

30. A stent according to claim 26 wherein the compensation maintains a stent area which is more constant on the inside and on the outside of the curve than it would without the compensation.

31. A stent according to claim 30 wherein said stent is coated with a medicine and said more constant density of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

32. The stent according to claim 26, wherein the shape of the loops provides radial strength to the stent to enable the stent to maintain a blood vessel at a desired inner diameter.

33. The stent according to claim 26, wherein the stent defines a plurality of enclosed spaces, with each longitudinal end of the enclosed space being formed by loops of the first meander pattern.

34. The stent according to claim 33 wherein the enclosed spaces are substantially the same size.

35. A stent formed of a tube having a patterned shape comprising:

a. even first meander patterns having axes extending in a first direction;

b. odd first meander patterns having axes extending in said first direction, wherein the odd first meander patterns are 180°

out of phase with the even first meander patterns, the even first meander patterns and the odd first meander patterns alternating with and spaced from each other;

c. second meander patterns having axes extending in a second direction different from the first direction horizontally, the second meander patterns being interconnected with the even and odd first meander patterns to form a generally uniform distributed structure;

d. wherein the first and second meander patterns have loops,

e. wherein the even and odd first meander patterns are interconnected to leave a portion of the second meander patterns in the space between adjacent even and odd first meander patterns,

f. wherein the portions of the second meander patterns between adjacent even and odd first meander patterns are adapted to lengthen and to compensate for the tendency of the loops of the first meander patterns to foreshorten when the stent is expanded,

g. wherein the first and second meander patterns are interconnected to leave only two loops of the first meander patterns between each pair of second meander patterns, and

h. wherein the portion of the second meander pattern between adjacent even and odd first meander patterns, and loops of the first meander pattern, are adapted to cooperate so that, when the expanded stent is in a curved vessel, on the outside of the curve, a circumferential compression and horizontal expansion of the loops in said first meander pattern substantially compensates for a horizontal expansion and circumferential compression of the loops in said second meander pattern and, on the inside of the curve, vice versa.

36. A stent according to claim 35, wherein on the outside of the curve, the portion of the second meander pattern between adjacent even and odd first meander patterns includes at least one loop and, on the outside of the curve, the loops in said second meander pattern become more open and the loops in the first meander pattern more closed, and on the inside of the curve, the loops in said second meander pattern become more closed and the loops in the first meander pattern more open.

37. A stent according to claim 35 wherein the compensation maintains a density of stent element area which is more constant on the inside and on the outside of the curve than it would without the compensation.

38. A stent according to claim 37 wherein said stent is coated with a medicine and said more constant density of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

39. A stent according to claim 35 wherein the compensation maintains a stent area which is more constant on the inside and on the outside of the curve than it would without the compensation.

40. A stent according to claim 39 wherein said stent is coated with a medicine and said more constant density of stent elements results in a more even dose being applied to the inside wall of the lumen, lowering the probability that a toxic dose is supplied at one area while a less than effective dose is supplied to another area.

41. The stent according to claim 35, wherein changes in the shape of the loops provide radial strength to the stent upon expansion to enable the stent to maintain a blood vessel at a desired inner diameter.