AU8558498A

AU8558498A - Stent with changeable cross-sectional area

Info

Publication number: AU8558498A
Application number: AU85584/98A
Authority: AU
Inventors: Benny Gaber
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-09-15
Filing date: 1998-07-30
Publication date: 1999-04-05
Also published as: JP2001516615A; WO1999013800A1; EP1014889A1; CA2303917A1; IL121771A0; PL339250A1; KR20010023950A

Description

WO 99/13800 1 PCT/IL98/00358 STENT WITH CHANGEABLE CROSS-SECTIONAL AREA FIELD OF THE INVENTION The present invention relates generally to a stent with a selectively changeable cross-sectional area which is easily inserted into and removed from a body vessel. 5 BACKGROUND OF THE INVENTION Stents are well known tubular support structures inserted into body vessels, ducts, lumens and the like, in various medical procedures. For example, stents may be inserted in strictures in the common bile duct, blood vessels, urethra and other organs. Stents are generally mounted on a delivery catheter which is inserted over a thin guidewire. The catheter 10 is introduced into the particular vessel and the stent is released from the catheter and fixed in a chosen location in the vessel. Expandable stents are known in the art. For example, a self-expanding stent for endoscopic and transhepatic applications, marketed under the trademark WALLSTENT' by Schneider (Europe) AG, Switzerland, includes a body made of stainless steel monofilament 15 wire braided in a tubular mesh configuration. The stent is introduced on a 7F or 9F delivery catheter and once in place expands to a larger diameter, such as to 30F. In general, expandable stents of the art are only expandable to a single, final diameter. However, the prior art does not show a stent which is selectively expandable/contractible throughout a range of diameters. 20 Some stents must be removed after therapy is complete. However, although insertion of stents is straightforward, generally removal of stents is more difficult. SUMMARY OF THE INVENTION The present invention seeks to provide an improved stent that is selectively expandable/contractible throughout a range of cross-sectional areas. The stent of the present 25 invention is not only easily insertable, but also easily removable. There is thus provided in accordance with a preferred embodiment of the present invention a stent having a cross-sectional area, the stent being selectively and fixedly expandable throughout a range of cross-sectional areas. Preferably the stent is selectively and fixedly contractible throughout the range of cross-sectional areas. 30 The stent preferably includes a plurality of loops, each of the loops including an arcuately formed wire with a first end and a second end, the first end being attached to a first elongate member and the second end being attached to a second elongate member, the first and the second elongate members being arranged to slide with respect to each other along a WO 99/13800 2 PCT/IL98/00358 common longitudinal axis, wherein the loops are arranged in a row and spaced from each other along the longitudinal axis and wherein sliding of the first and the second elongate members with respect to each other changes a cross-sectional area of each of the loops. In accordance with a preferred embodiment of the present invention the first 5 and the second elongate members are selectively fixable with respect to each other along a range of positions along the longitudinal axis. Further in accordance with a preferred embodiment of the present invention the first and the second elongate members are toothed along the longitudinal axis such that the first and the second elongate members selectively and fixably mesh with each other along a range of 10 positions along the longitudinal axis. Still further in accordance with a preferred embodiment of the present invention the first and the second elongate members respectively include a longitudinal tenon and a longitudinal groove, the tenon sliding in the groove. Additionally in accordance with a preferred embodiment of the present 15 invention at least two of the loops are connected by a connecting filament. In accordance with a preferred embodiment of the present invention at least one of the loops is at least partially wrapped by a covering. Further in accordance with a preferred embodiment of the present invention at least one of the loops has a different cross-sectional area than another one of the loops. The 20 wires may be flexible. The first and the second elongate members may each include a grasping portion at a proximal end thereof In accordance with another preferred embodiment of the present invention the stent includes a pair of half-cylinders partially nested in each other along a common longitudinal axis, each half-cylinder including a plurality of pins spaced in a row generally 25 parallel to the longitudinal axis, wherein each of the pins slidingly mates with a helical slot correspondingly formed in the other half-cylinder, such that moving the half-cylinders with respect to each other moves the pins in the slots in a screw-thread manner, thereby changing the amount of nesting of the half-cylinders in each other and changing a cross-sectional area of the stent. 30 BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: WO 99/13800 3 PCT/IL98/00358 Fig. I is a simplified pictorial illustration of a stent constructed and operative in accordance with a preferred embodiment of the present invention, and comprising a plurality of loops of wire attached to a pair of elongate members; Fig. 2 is a simplified pictorial illustration of the stent of Fig. 1 with one elongate 5 member slid along a longitudinal axis with respect to the other elongate member; Figs. 3 and 4 are simplified side view illustrations of connections of ends of each wire to the elongate members in accordance with two alternative preferred embodiments of the present invention; Figs. 5 and 6 are simplified top view illustrations of the stent of Fig. 1, 10 corresponding respectively to Figs. 1 and 2; Figs. 7 and 8 are simplified front view illustrations of the stent of Fig. 1, corresponding respectively to Figs. I and 2; Fig. 9A is a simplified pictorial illustration of a stent constructed and operative in accordance with another preferred embodiment of the present invention, and comprising a 15 pair of half-cylinders partially nested in each other along a common longitudinal axis; Fig. 9B is a simplified pictorial illustration of another preferred embodiment of the stent of Fig. 9A wherein the half-cylinders form a single cylinder; Figs. 10 and 11 are simplified top view illustrations of the stent of Fig. 9, respectively before and after moving the half-cylinders with respect to each other; and 20 Figs. 12 and 13 are simplified front view illustrations of the stent of Fig. 9, corresponding respectively to Figs. 10 and 11. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Reference is now made to Fig. I which illustrates a stent 10 constructed and operative in accordance with a preferred embodiment of the present invention. 25 Stent 10 includes a plurality of loops 12, each loop 12 constructed of an arcuately formed wire 14 with a first end 16 and a second end 18. It is noted that throughout the specification and claims the term wire encompasses any slender element having any cross sectional shape, such as wire, rod, bar, cable, or the like. Wire 14 is typically made of any medically safe material and may be flexible if desired. First end 16 is preferably attached to a 30 first elongate member 20 and second end 18 is preferably attached to a second elongate member 22. First and second elongate members 20 and 22 are arranged to slide with respect to each other along a common longitudinal axis 24. Loops 12 are arranged in a row and spaced WO 99/13800 4 PCT/IL98/00358 from each other along axis 24 and in Fig. I loops 12 have a generally circular cross-sectional area. Reference is now made to Figs. 3 and 4 which illustrate alternative connections of wire 14 to first and second elongate members 20 and 22. In Fig. 3, first and second ends 16 5 and 18 are flush with first and second elongate members 20 and 22. In Fig. 4, first and second ends 16 and 18 are not flush with first and second elongate members 20 and 22. It is seen that first and second elongate members 20 and 22 respectively comprise a longitudinal tenon 26 and a longitudinal groove 28, and tenon 26 slides in groove 28. First and second elongate members 20 and 22 are preferably selectively fixable o10 with respect to each other along a range of positions along axis 24. One method of selectively fixing first and second elongate members 20,and 22 with respect to each other is illustrated in Figs. 3 and 4. First and second elongate members 20 and 22 may be provided with teeth 30 along axis 24. Teeth 30 may be selectively and fixably meshed with each other along a range of positions along axis 24. 15 At least two, and preferably all, of loops 12 may be connected by a connecting filament 32, such as a thread or any non-rigid wire. Preferably at least one of, and most preferably all of, loops 12 is at least partially wrapped by a covering 34. Covering 34 is useful in preventing tissue from bulging between loops 12. Optionally, at least one of the loops 12, designated by reference numeral 36 and shown in phantom lines Fig. 1, has a different cross 20 sectional area than another one of the loops 12. Preferably first and second elongate members 20 and 22 include grasping portions 38 and 40, respectively, at a proximal ends of each elongate member. Elongate members 20 and 22 may be slid with respect to each other by grasping grasping portions 38 and 40 with any convenient tool. 25 Top and side views of the configuration of Fig. 1 are shown respectively in Figs. 5 and 7. Reference is now made to Fig. 2 which illustrates changing the cross-sectional area of loops 12 of stent 10. This is accomplished by sliding one elongate member, such as second elongate member 22, along axis 24, such as in the direction of an arrow 42, with 30 respect to the other elongate member, such as first elongate member 20. Top and side views of the configuration of Fig. 2 are shown respectively in Figs. 6 and 8. It is seen especially in Figs. 6 and 8 that instead of the generally circular cross-sectional shape of loops 12 in Figs. 1, 5 and 7, loops 12 now have a smaller, generally elliptic cross-sectional shape. First and second WO 99/13800 5 PCT/IL98/00358 elongate members 20 and 22 may be slid with respect to each other any desired amount to obtain any desired cross-sectional size. First and second elongate members 20 and 22 are fixed in the desired position by the meshing, locking action of teeth 30 with each other. It is appreciated that other mechanisms instead of teeth may be employed to fix the position of first 5 and second elongate members 20 and 22 with respect to each other. Reference is now made to Fig. 9A which illustrates a stent 50 constructed and operative in accordance with another preferred embodiment of the present invention. Stent 50 preferably includes a pair of half-cylinders 52 and 54 partially nested in each other along a common longitudinal axis 56. Each half-cylinder 52 and 54 includes a plurality of pins 58 10 spaced in a row generally parallel to axis 56. Each pin 58 slidingly mates with a helical slot 60 correspondingly formed in the other half-cylinder, such that moving half-cylinders 52 and 54 with respect to each other moves pins 58 in slots 60 in a screw-thread manner, thereby changing the amount of nesting of half-cylinders 52 and 54 in each other. Fig. 9B illustrates another preferred embodiment of stent 50 wherein half-cylinders 52 and 54 form a single 15 cylinder 55. Reference is now made to Figs. 10 and 11 which are simplified top view illustrations of stent 50, respectively before and after moving half-cylinders 52 and 54 with respect to each other. Reference is also made to Figs. 12 and 13 which are simplified front view illustrations of stent 50, corresponding respectively to Figs. 10 and 11. It may be seen 20 particularly in Figs. 12 and 13 that moving half-cylinders 52 and 54 with respect to each other changes the cross-sectional area of stent 50. In Fig. 10, it is seen that slots 60 may have teeth 62 formed therein so that pins 58 may be fixed in the desired position in slots 60 by lockingly meshing with teeth 62. It is appreciated that other mechanisms instead of teeth may be employed to fix the position of pins 58 in slots 60. 25 It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior 30 art.

Claims

1. A stent (10, 50) having a cross-sectional area, said stent (10, 50) being selectively and fixedly expandable throughout a range of cross-sectional areas. 5

2. The stent (10, 50) according to claim I and wherein said stent (10, 50) is selectively and fixedly contractible throughout said range of cross-sectional areas.

3. The stent (10) according to claim 1 and comprising a plurality of loops (12), each of said loops (12) comprising an arcuately formed wire (14) with a first end (16) and a second end (18), said first end (16) being attached to a first elongate member (20) and said 10 second end (18) being attached to a second elongate member (22), said first and said second elongate members (20, 22) being arranged to slide with respect to each other along a common longitudinal axis (24), wherein said loops (12) are arranged in a row and spaced from each other along said longitudinal axis (24) and wherein sliding of said first and said second elongate members (20, 22) with respect to each other changes a cross-sectional area of each of said 15 loops (12).

4. The stent (10) according to claim 3 and wherein said first and said second elongate members (20, 22) are selectively fixable with respect to each other along a range of positions along said longitudinal axis (24).

5. The stent (10) according to claim 3 and wherein said first and said second 20 elongate members (20, 22) are toothed along said longitudinal axis (24) such that said first and said second elongate members (20, 22) selectively and fixably mesh with each other along a range of positions along said longitudinal axis (24).

6. The stent (10) according to claim 3 and wherein said first and said second elongate members (20, 22) respectively comprise a longitudinal tenon (26) and a longitudinal 25 groove (28), said tenon (26) sliding in said groove (28).

7. The stent (10) according to claim 3 and wherein at least two of said loops (12) are connected by a connecting filament (32).

8. The stent (10) according to claim 3 and wherein at least one of said loops (12) is at least partially wrapped by a covering (34). 30

9. The stent (10) according to claim 3 and wherein at least one of said loops (12) has a different cross-sectional area than another one of said loops (12).

10. The stent (10) according to claim 3 and wherein said wires (14) are flexible. WO 99/13800 7 PCT/IL98/00358

11. The stent (10) according to claim 3 and wherein said first and said second elongate members (20, 22) each comprise a grasping portion (38, 40) at a proximal end thereof

12. The stent (50) according to claim 1 and comprising a pair of half-cylinders (52, 5 54) (52, 54) partially nested in each other along a common longitudinal axis (56), each said half-cylinder (52, 54) comprising a plurality of pins (58) spaced in a row generally parallel to said longitudinal axis (24), wherein each of said pins (58) slidingly mates with a helical slot (60) correspondingly formed in the other half-cylinder (52,54), such that moving said half cylinders (52, 54) with respect to each other moves said pins (58) in said slots (60) in a screw 10 thread manner, thereby changing the amount of nesting of said half-cylinders (52, 54) in each other.

13. The stent (50) according to claim 12 and wherein said half-cylinders (52, 54) form a single cylinder (55).

14. The stent (50) according to claim 12 and wherein said slots (60) have teeth (62) 15 formed therein so that said pins (58) are fixable in a desired position in said slots (60) by lockingly meshing with said teeth (62).