AU754584B2 - Articulated stent - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

.5555.

*5

S

*4 5.55 555.5.

Name of Applicant: Actual Inventors: Address for Service: Invention Title: Medinol Ltd., of Kiryat Atidim, P.O. Box 58165, 61581 Tel Aviv, ISRAEL PINCHASIK, Gregory RICHTER, Jacob DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne 3000, Victoria, Australia "Articulated Stent" S 55 S S

S

The following statement is a full description performing it known to us: of this invention, including the best method of -1- ARTICULATED STENT FIELD AND BACKGROUND OF THE INVENTION The present invention relates to stents which are implanted as part of a balloon angioplasty procedure within a bodily conduit of a living animal or a human to maintain patency. In particular, the present invention relates to articulated intravascular stents for delivery through or implantation in a blood vessel having a curved portion.

10 Intravascular stents having a constricted diameter for delivery through a blood vessel and an expanded diameter for applying a radially outwardly extending force for supporting the blood vessel are known in the art. Articulated intravascular stents for either delivery through a curved blood vessel or implanted therein are also known in the art.

15 Self-expandable articulated stents are described, for example, in U.S.

Patent No. 5,104,404 entitled "Articulated Stent" to Wolff. Balloon expandable articulated stents are commercially available under the trade name Palmaz-Schatz Balloon-Expandable Stents from Johnson Johnson Intervention Systems Co.

A prior art self-expandable articulated intravascular stent deployed in a curved blood vessel 16 is now described with reference to Figure I which is, in actual fact, Figure 2 of the above referenced U.S.

Patent No. 5,104,404. Stent 10 is made up of a number of individual 2 segments 12 articulated by hinges 14 connected at each end to segments 12. Stent 10 is preferably fabricated from memory shape material, for example, nitinol, and as such is self expandable after delivery from a delivery system described in U.S Patent No. 4,830,003 to Wolff et al.

However, these prior art articulated intravascular stents suffer from a number of disadvantages both during delivery through a curved blood vessel and when implanted therein as will now described.

The delivery of stent 10 through curved blood vessel 16 is more complicated than the delivery of a non-articulated stent in that stent 10 has 10 to be angularly oriented such that its hinges 14 are located towards the convex portion of blood vessel 16 so that stent 10 can be flexed inward.

In the present example, it will be noted that hinges 14 are located on the same side of segments 12 because blood vessel 16 has only a simple curve in one plane. It can be readily appreciated that delivery of stents through 15 blood vessels which have one or more curved portions which are not in the same plane is even more complicated and generally requires specially S constructed stents.

Even when implanted in a curved blood vessel 16, stents 10 are shown to be lacking in that the gaps between segments 12 render the curved portion of blood vessel 16 without support. Furthermore, the gaps at the convex portion of blood vessel 16 are substantially greater than the P:\OPER\ArI\14HI6OO spedoc-I9/09AO2 -3gaps at the concave portion thereof, thereby inducing non-uniform and therefore undesirable stresses on blood vessel 16.

Therefore, it would be highly desirable to have an articulated stent which does not require any particular angular orientation when being delivered through a curved bodily conduit and provides continuous and uniform support for both straight and curved portions of a bodily conduit when implanted.

It would also be highly desirable the structure of a stent does not depend on the particular orientations of curved portions of a blood vessel.

In accordance with one aspect of the present invention, there is provided a 10 connector for connecting adjacent substantially tubular and substantially rigid segments of an expandable articulated stent, comprising: a flexible link having at least a first portion and a second portion and when viewed laterally an area of inflection disposed between said first portion and said second portion.

Another aspect of the present invention provides a connector for connecting adjacent substantially tubular and substantially rigid segments of an expandable articulated stent, comprising: a flexible link having at least a first portion, a second portion and a third portion, said link when viewed laterally having: 20 a first area of inflection disposed between said first portion and said second 9 iportion; and a second area of inflection disposed between said second portion and said third portion.

A further aspect of the present invention provides a connector for connecting segments of an expandable articulated stent, comprising: a flexible link having at least a first portion, a second portion and a third portion; said link when viewed laterally having an area of inflection disposed between each of said portions, said areas of inflection disposed in substantially opposed directions.

PAOPER\I\4HU64o IP A-.I19A)9/02 -3A- Another aspect of the present invention provides an expandable articulated stent having a longitudinal axis and a circumferential axis, including: a) a plurality of substantially tubular and substantially rigid segments defining a longitudinal aperture, and b) a plurality of flexible connecting links connecting said rigid segments, each of said flexible links having a first portion and a second portion, each of said links when viewed laterally having an area of inflection disposed between said portions.

A further aspect of the present invention provides an expandable articulated stent having a longitudinal axis and a circumferential axis, including: 10 a) a plurality of substantially tubular and substantially rigid segments defining a longitudinal aperture, and b) a plurality of flexible connecting links connecting said rigid segments, each of said flexible links having a first portion and a second portion, each of said links when viewed laterally having an area of inflection disposed between said portions, wherein each of said flexible connecting links extends between and connects two of said plurality of segments, wherein said plurality of flexible links are provided with *.g.*end points at which said links are joined to said segments, wherein said end points of said flexible connecting links are aligned substantially longitudinally with said longitudinally extending aperture, 20 wherein said flexible connecting links are adapted to substantially compensate for the tendency of said segments to foreshorten when said stent is expanded, and wherein said stent is expanded as by an inflatable balloon inflated within said longitudinal aperture.

Yet another aspect of the present invention provides an expandable articulated stent having a longitudinal axis and a circumferential axis, including: a) a plurality of substantially tubular and substantially rigid segments defining a longitudinal aperture, and b) a plurality of flexible connecting links connecting said rigid segments, each of said flexible links having a first portion and a second portion, each of said links when viewed laterally having an area of inflection disposed between said portions, *wherein said stent is expanded as by an inflatable balloon inflated within said P:\OPER\Ar\!48i64X0 spodoc. 19109102 -3B longitudinal aperture, wherein said links do not tend to project into or outside of said longitudinal aperture of said stent when said stent is expanded, and wherein said links do not tend to project into or outside of said longitudinal aperture of said stent when said stent is flexed.

A yet further aspect of the present invention provides an articulated stent, comprising: a) at least two substantially rigid segments having a plurality of connected cells each having apices, wherein, upon expansion, each of said rigid segments presents a substantially cylindrical structure; and 10 b) a flexible connector, comprising a plurality of flexible links, disposed between the substantially rigid segments, each of the links connecting apices of adjacent cells on adjacent rigid segments, each of the links having at least a first portion and a second portion and an area of inflection disposed between the first portion and the second portion in the lateral direction.

4 After expansion, the rigid segments of the stent preferably present a fine diamond shaped mesh having 1 mm long sides to provide continuous and uniform support for straight portions of a bodily conduit.

The connectors can be implemented as a plurality of substantially helical links connecting adjacent segments. Alternatively, the connectors can be implemented as links each having at least one kink. The connectors typically have between 8-24 links to provide continuous and uniform support for both straight and curved portions of a bodily conduit.

The stents have constricted diameters for intraluminal delivery and are then deformed, by the inflation of a balloon forming part of their catheter delivery system, to expanded diameters for applying radially outwardly extending forces for supporting the lumen of bodily conduits.

The constricted and expanded diameters of the stents typically fall in the ranges of 1.0-3.5 mm and 3.5-10.0 mm, respectively.

The stents are preferably fabricated from low memory, more plastic than elastic, bio-compatible materials, for example, stainless steel 316L, gold. tantalum, etc. which enables them to be plastically deformed from their constricted diameters to their expanded diameters.

A typical stent for implantation in a human coronary artery is 9-21 mm long comprising three to seven 2.2 mm long stent segments connected by two to six 1 mm long connectors such that the ends of the stent subtend between a 45° to 135° angle at a radius of curvature of approximately 9 mm when flexed.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are described, by way of example only, with reference to the accompanying drawings, wherein: FIG. I shows a close-up view of a prior art articulated stent of deployed in a curved blood vessel; FIGS. 2a and 2b show a preferred embodiment of an articulated stent, construct-andoperative according to the teachings of-the-present invention, in its relaxed and flexed states before plastic deformation; FIG. 2c shows the expanded stent of Figure 2 after plastic •deformation; FIG. 2d shows the stent of Figure 2 mounted on a catheter in its flexed state; FIGS. 2e and 2f show the stent of Figure 2 before and after expansion by a balloon forming part of its catheter delivery system; FIGS. 3a and 3b show a second embodiment of an articulated stent, constructed and operative according to the teachings of the present invention, in its relaxed and flexed states before plastic deformation; and PAOPERMAHU64- spc.dom.19/09/02 -6- FIG. 3c shows the expanded stent of Figure 3 after plastic deformation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention are of an articulated stent for delivering through a curved bodily conduit, for example, a peripheral or coronary artery of a living animal or a human and implantation therein as part of a balloon angioplasty procedure to maintain patency.

The principles and operation of the articulated stent of the preferred embodiments may be better understood with reference to the drawings and the 10 accompanying description.

S* Referring now to the drawings, Figures 2a-2c show an articulated stent, generally designated 100, constructed and operative according to the teachings of the preferred embodiments, generally comprising a number of substantially rigid S"segments 102 connected by connectors 110.

Segments 102 are preferably made up to present a fine diamond mesh of interconnected diamond shaped cells 108 having 1 mm sides on expansion as best 0 seen in Figure 2c. Depending on the intended diameter of stent 100, segments 102 typically comprise between 8-24 diamond shaped cells 108.

Connectors 110 comprise links 112 connecting a front end 104 to a tail end 20 106 of adjacent segments 102. Links 112 preferably extend in 7 a substantially helical fashion between apexes of diamond shaped cells 108 at front and rear ends 104 and 106 of adjacent segments 102 such that the number of links 112 equals the number of cells 108. Links 112 are preferably evenly deployed around perimeters of segments 102 such that connectors 110 can be equally flexed in any direction and to provide continuous and uniform support to both straight and curved portions of a bodily conduit.

Alternate connectors 110 at front and rear ends 104 and 106, respectively, of a segment 102 preferably have links 112 wound in clockwise and counter clockwise directions. Alternately winding connectors 110 ensures that the rotational displacement of links 112 and adjacent segments 102 relative to the walls of a blood vessel and more importantly the balloon of its delivery system is minimized when stent 100 is expanded.

5 It is particular feature of the preferred embodiment that connectors 110 have a generally cylindrical configuration when stent 100 is relaxed as best seen in Figure 2a and a differentially stretched and compressed curved configuration when stent 100 is flexed as best seen in Figure 2b. The flexed configuration is brought about by two relatively opposing displacements of links 112. First, the differential stretching of connectors 110 occurs at the convex portion thereof denoted 114 by links 112 being displaced away from one another. Second, the differential compressing of 8 connectors 110 occurs at the concave portion thereof denoted 116 by links 112 being displaced towards one another.

Stent 100 has a constricted diameter for delivery through a curved bodily conduit as shown in Figures 2a and 2b and an expanded diameter as shown in Figure 2c for supporting a bodily conduit. Stent 100 is preferably fabricated from low memory, more plastic than elastic, biocompatible material, for example, stainless steel 316L, gold, tantalum, etc.

which enables it to be plastically deformed from its constricted diameter to its expanded diameter. The constricted and expanded diameters of stent 10 100 typically fall in the ranges of 1.0-3.5 mm and 3.5-10.0 mm, respectively.

With reference now to Figures 2d-2f, stent 100 is shown overlying a balloon 118 forming part of its catheter delivery system 120. Stent 100 is mounted on its catheter delivery system 120 in its constricted diameter state shown in Figure 2e for plastic deformation through inflation of balloon 118 to its expanded diameter shown in Figure 2f for supporting the walls of a bodily conduit. An exemplary stent for implantation in a human coronary artery, is typically 15 mm long made up of five 2.2 mm long segments 102 connected by four 1 mm long connectors 110 and capable of flexion such that its ends subtend a 90° angle at a radius of curvature of approximately 9 mm.

9 The delivery of articulated stent 100 is considerably simpler than the delivery of prior art articulated stent 10 because stent 100 is equally flexible in all direction and therefore does not require a dedicated angular orientation to pass a particular curved portion. This advantage is particularly important for delivery through blood vessels having multiple curved portions. It is a further advantage of stent 100 over prior art stents that stent 100 provides continuous and uniform support along the entire length of a blood vessel by means of segments 102 and unflexed connectors 110 supporting straight portions thereof while connector 10 portions 114 and 116 supporting convex and concave curved portions thereof, respectively.

With reference now to Figures 3a and 3b, an articulated stent 122 is shown in which connectors 124 comprise links 126 having one or more kinks 128. The design of connectors 124 is preferred to that of connector 15 110 because stent 100 may have a tendency to rupture balloon 118 due to two reasons. First, links 112 overlying the convex portion of balloon 118 have a tendency to be biased inward when stent 100 is flexed. Second, segments 102 display a rotational displacement relative to balloon 118 when stent 100 is expanded.

In this case, the differentially stretched and compressed curved configuration of connector 124 is brought about by two relatively opposing displacements of links 112 as before except that the differential stretching P:\OPER\GCP\24279.DIV 31/1/00 of connectors 124 at convex portion 114 occurs by kinks 128 being somewhat straightened out while the differential compressing of connectors 124 at concave portion 116 occurs by kinks 128 being more acutely bent.

In a similar fashion to stent 100, stent 122 has a constricted diameter for delivery through a curved bodily conduit as shown in Figures 3a and 3b and an expanded diameter as shown in Figure 3c for supporting a bodily conduit when implanted therein.

While the invention has been described with respect to a limited number of 10 embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

o* The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

oo

Claims (32)

1. A connector for connecting adjacent substantially tubular and substantially rigid segments of an expandable articulated stent, comprising: a flexible link having at least a first portion and a second portion and when viewed laterally an area of inflection disposed between said first portion and said second portion.

2. The connector according to claim 1, wherein said area of inflection remains 10 inflected after the expansion of said stent.

3. The connector of claim 1, in which the area of inflection enlarges during the expansion of the stent.

4. The connector of any one of claims 1-3, in which said portions are generally S. straight.

5. A connector for connecting adjacent substantially tubular and substantially rigid segments of an expandable articulated stent, comprising: 20 a flexible link having at least a first portion, a second portion and a third portion, said link when viewed laterally having: a first area of inflection disposed between said first portion and said second portion; and a second area of inflection disposed between said second portion and said third portion.

6. The connector of claim 5, wherein said first area of inflection and said second area of inflection remain inflected after the expansion of said stent. S

7. The connector of claim 5 in which said first area of inflection and said second S area of inflection enlarge during the expansion of said stent. P \OPER\Ari\I4K I64M( spc.doc.19/09/()2 -12-

8. The connector of any one of claims 5-7, in which said portions are generally straight.

9. A connector for connecting segments of an expandable articulated stent, comprising: a flexible link having at least a first portion, a second portion and a third portion; said link when viewed laterally having an area of inflection disposed between each of said portions, said areas of inflection disposed in substantially opposed 10 directions. .2

10. The connector according to claim 9, wherein said areas of inflection enlarge during the expansion of said stent.

11. An expandable articulated stent having a longitudinal axis and a circumferential axis, including: a) a plurality of substantially tubular and substantially rigid segments defining a longitudinal aperture, and *00000 b) a plurality of flexible connecting links connecting said rigid segments, each :0.06. 20 of said flexible links having a first portion and a second portion, each of said links when viewed laterally having an area of inflection disposed between said portions.

12. The stent of claim 11, wherein each of said flexible connecting links extends between and connects two of said plurality of segments.

13. The stent of claim 12, wherein said plurality of flexible links are provided with end points at which said links are joined to said segments.

14. The stent of claim 13, wherein said end points of said flexible connecting links 0 are aligned substantially longitudinally with said longitudinally extending aperture.

P:AOPER\Ar[X48164O spc.doc-I9109/02 13 The stent of any one of claims 11-14 wherein said flexible connecting links are adapted to substantially compensate for the tendency of said segments to foreshorten when said stent is expanded.

16. The stent of any one of claims 11-14 wherein said stent is expanded as by an inflatable balloon inflated within said longitudinal aperture.

17. The stent of any one of claims 11-14 wherein said flexible connecting links open to longitudinally lengthen and substantially compensate for the longitudinal 10 movement away from each other of the adjacent ends of said connected rigid segments when said stent is expanded. •0.0

18. The stent of any one of claims 11-14 wherein said segments do not tend to .0o: rotate relative to each other when said stent is expanded.

19. The stent of any one of claims 11-14 wherein said links do not tend to project into or outside of said longitudinal aperture of said stent when said stent is expanded. *ooo

20. The stent of any one of claims 11-14, wherein said links do not tend to project 20 into or outside of said longitudinal aperture of said stent when said stent is flexed.

21. The stent of any one of claims 11-14, wherein said segments display substantially no rotational displacement relative to a balloon disposed in said longitudinal bore when said stent is expanded by said balloon.

22. An expandable articulated stent having a longitudinal axis and a circumferential axis, including: a) a plurality of substantially tubular and substantially rigid segments defining a longitudinal aperture, and b) a plurality of flexible connecting links connecting said rigid segments, each S of said flexible links having a first portion and a second portion, each of said links P:\OPER\A,1\[48364W( sp .dm-19/9AAQ -14- when viewed laterally having an area of inflection disposed between said portions, wherein each of said flexible connecting links extends between and connects two of said plurality of segments, wherein said plurality of flexible links are provided with end points at which said links are joined to said segments, wherein said end points of said flexible connecting links are aligned substantially longitudinally with said longitudinally extending aperture, wherein said flexible connecting links are adapted to substantially compensate for the tendency of said segments to foreshorten when said stent is expanded, and wherein said stent is expanded as by an inflatable balloon inflated within said 10 longitudinal aperture.

23. An expandable articulated stent having a longitudinal axis and a circumferential axis, including: a) a plurality of substantially tubular and substantially rigid segments defining a longitudinal aperture, and b) a plurality of flexible connecting links connecting said rigid segments, each of said flexible links having a first portion and a second portion, each of said links when viewed laterally having an area of inflection disposed between said portions, wherein said stent is expanded as by an inflatable balloon inflated within said longitudinal aperture, wherein said links do not tend to project into or outside of said longitudinal aperture of said stent when said stent is expanded, and wherein said links do not tend to project into or outside of said longitudinal aperture of said stent when said stent is flexed.

24. An articulated stent, comprising: a) at least two substantially rigid segments having a plurality of connected cells each having apices, wherein, upon expansion, each of said rigid segments presents a substantially cylindrical structure; and b) a flexible connector, comprising a plurality of flexible links, disposed 30 between the substantially rigid segments, each of the links connecting apices of adjacent cells on adjacent rigid segments, each of the links having at least a first P OPERkAri\148 164X0 spe.doc.20109/)2 portion and a second portion and an area of inflection disposed between the first portion and the second portion in the lateral direction.

The articulated stent of claim 24, wherein the area of inflection remains inflected after the expansion of the stent.

26. The articulated stent of claim 24, wherein the area of inflection enlarges during the expansion of the stent. 10

27. The articulated stent of any one of claims 24-26, wherein the first portion and :second portion are substantially straight.

28. The articulated stent of any one of claims 24-27, wherein said substantially rigid segments are substantially rigid particularly when compared to said flexible connectors disposed between the substantially rigid segments.

29. The articulated stent of any one of claims 24-28, wherein the substantially cylindrical structure comprises a mesh.

30. A connector, substantially as described with reference to the drawings.

31. An articulated stent, substantially as described with reference to the drawings.

32. An expandable articulated stent, substantially as described with reference to the drawings. DATED this 20th day of September, 2002 Medinol Ltd. By DAVIES COLLISON CAVE Patent Attorneys for the Applicant