STENT FOR SPLINTING A VEIN, AND SYSTEM FOR PUTTING IN PLACE A STENT

Abstract

The invention relates to a stent and a system for putting in place a stent. Said stent is used especially for splinting a vein and consists of a braided, tubular supporting member (2) that has a minimum length of 60 mm. The supporting member is braided from one or more wires in such a way that portions of the wire or wires, resp., delimit rhombuses. The disclosed stent is characterized in that in the unloaded state of the stent, the longitudinal size of most of the rhombuses (7) in the longitudinal direction (15) of the stent (1) is not shorter than the transversal size of the rhombuses.

Claims

1-24. (canceled)

25. A stent for splinting a vein, the stent comprising a braided tubular supporting member that has a length of at least 60 millimeters (mm), the supporting member being braided with one or more wires with sections of the wire or the wires, respectively, delimiting rhombuses, wherein the stent has at least one reinforcement section and at least one hinge section, with the rhombuses in the reinforcement section being shorter in longitudinal direction than the rhombuses of the hinge section.

26. The stent according to claim 25, wherein the stent provides at least two reinforcement sections, wherein between two neighboring reinforcement sections at least one hinge section is arranged.

27. The stent according to claim 25, wherein, the reinforcement section is shorter in longitudinal direction than the hinge section.

28. The stent according to claim 25, wherein, several reinforcement sections are provided in periodical distances, in which the sections preferably are in the range of 2 to 5 centimeters (cm).

29. The stent according to claim 25, wherein in unloaded state of the stent the longitudinal extension of the majority of the rhombuses in longitudinal direction of the stent is not shorter than the transversal extension of the rhombuses.

30. The stent according to claim 29, wherein, the longitudinal extension of the rhombuses in unloaded state of the stent is greater than the transversal extension, wherein the longitudinal extension preferably is at least 10% greater than the transversal extension.

31. The stent according to claim 29, wherein, the longitudinal extension of the rhombuses in unloaded state of the stent is not greater than the 1.5 fold of the transversal extension.

32. The stent according to claim 25, in which strands of the wires extend along the entire length of the stent, wherein the number of strands results from multiplication of the wire diameter (D.sub.d) with the stent diameter (D.sub.s) and a factor (F), wherein the herefrom resulting calculated value n is rounded up or down, respectively, and the factor (F) dependent from the wire diameter (D.sub.d) is determined by one or more of the following spline functions, and the factor (F) is subject to a tolerance of ±30%:
(for 0.05≦D.sub.d≦0.08)
F=91.64+44.35 D.sub.d−20553.34 D.sub.d.sup.2+137022.25 D.sub.d.sup.3   Polynomial 1:
(for 0.08<D.sub.d≦0.1)
F=255.59+−6103.93 D.sub.d+56300.07 D.sub.d.sup.2−183200.28 D.sub.d.sup.3   Polynomial 2:
(for 0.1<D.sub.d≦0.12)
F=54.05+−90.64 D.sub.d−3668.35 D.sub.d.sup.2+16694.46 D.sub.d.sup.3   Polynomial 3:
(for 0.12<D.sub.d≦0.15)
F=113.30+−1576.24 D.sub.d+8730.26 D.sub.d.sup.2−17746.13 D.sub.d.sup.3   Polynomial 4:
(for 0.15<D.sub.d≦0.18)
F=38.95+−79.93 D.sub.d−1276.36 D.sub.d.sup.2+4490.79 D.sub.d.sup.3   Polynomial 5:
(for 0.18<D.sub.d≦0.2)
F=193.93+−2660.39 D.sub.d+13052.63 D.sub.d.sup.2−22044.37 hd d.sup.3   Polynomial 6:
(for 0.2<D.sub.d≦0.22)
F=−114.94+1969.54 D.sub.d−10089.39 D.sub.d.sup.2+16525.66 D.sub.d.sup.3   Polynomial 7:
(for 0.22<D.sub.d<0.25)
F=147.58+−1609.72 D.sub.d+6178.66 D.sub.d.sup.2−8122.89 D.sub.d.sup.3   Polynomial 8:
(for 0.25<D.sub.d≦0.3)
F=29.54+−194.24 D.sub.d+518.94 D.sub.d.sup.2−576.60 D.sub.d.sup.3   9:
(for 0.3<D.sub.d<0.35)
F=110.08+−910.08 D.sub.d+2572.00 D.sub.d.sup.2−2449.52 D.sub.d.sup.3   Polynomial 10:

33. The stent according to claim 32, wherein, the factor F is subject to a tolerance of ±20%.

34. The stent according to claim 25, wherein, the wires are made from nitinol and have a wire diameter from 0.05 mm to 0.35 mm.

35. The stent according to claim 25, wherein, the individual strands of the at least one wire are pairwise inter-connected to each other by a bent section at at least one end of the stent so that they form at least one round end.

36. The stent according to claim 25, wherein, the strands are twisted together at at least one end of the stent.

37. The stent according to claim 36, wherein, at the pairwise twisted ends of the strands loops are provided and/or the pairwise twisted ends of the strands are welded together.

38. The stent according to claim 25, wherein, the stent provides at least one twisted section in which two or more sections of the wire or wires, respectively, are twisted together, wherein the twisted region preferably extends over a short region in longitudinal direction of the stent and along the entire circumference of the stent.

39. The stent according to claim 25, wherein, the stent provides at least at one of the two ends a widened (flared) region relative to the other section of the stent.

40. The stent according to claim wherein, the widened region extends over a length of at least 5 mm and in particular provides a widening of the diameter of the stent of at least 0.5 mm.

41. The stent according to claim 39, wherein, in the widened region a reinforcement ring is provided.

42. The stent according to claim 41, wherein, the reinforcement ring provides rhombuses with a greater transversal extension than longitudinal extension relative to the other sections of the stent.

43. A method for splinting of a human or animal hollow vessel whereas a stent according to claim 25 is inserted into the hollow vessel.

44. A system for placing a stent in a vein, in which the stent is formed from a braided tubular supporting member, the system comprising an implantation catheter with a lumen for accommodating the stent in compressed state, a positioning catheter which is located inside the implantation catheter and can attach to the compressed stent, a flexible anchor wire which is threaded through openings of the stent, a latch wire which extends across the positioning catheter and is embraced by at least one loop of the anchor wire so that during removal of the latch wire the anchor wire is released and can be pulled out of the stent and the positioning catheter, wherein the latch wire releases the stent is released, wherein, the stent is provided according to claim 25.

45. A system for placing a stent in a vein, in which the stent is formed from a braided tubular supporting member, the system comprising: an implantation catheter with a lumen for accommodating the stent in compressed state, a positioning catheter which is located inside the implantation catheter and can attach to the compressed stent, a flexible anchor wire which is threaded through openings of the stent, a latch wire which extends across the positioning catheter and is embraced by at least one loop of the anchor wire so that during removal of the latch wire the anchor wire is released and can be pulled out of the stent and the positioning catheter, wherein the latch wire releases the stent is released.

46. The system according to claim 45, wherein, the positioning catheter provides at least two chambers extending across the entire length of the positioning catheter which are provided for accommodating a guidewire and for accommodating the latch wire or the anchor wire, respectively.

47. The system according to claim 45, wherein, the openings of the stent through which the anchor wire is threaded are arranged at the proximal end region of the stent.

48. A method for placing a stent in a vein, the method comprising: insertion into a vessel or a cavity, respectively, to be splinted in a human or animal body, of the distal end of a system for placing a stent in a vein, in which the stent is formed from a braided tubular supporting member, the system comprising an implantation catheter with a lumen for accommodating the stent in compressed state, a positioning catheter which is located inside the implantation catheter and can attach to the compressed stent, a flexible anchor wire which is threaded through openings of the stent, a latch wire which extends across the positioning catheter and is embraced by at least one loop of the anchor wire so that during removal of the latch wire the anchor wire is released and can be pulled out of the stent and the positioning catheter, wherein the latch wire releases the stent, retraction of the implantation catheter, releasing the stent, retraction of the latch wire, releasing the anchor wire, pulling out the anchor wire, the positioning catheter, and the implantation catheter of the vessel/cavity to be splinted.

Description

[0078] The invention hereinafter is explained in more detail by means of the drawings. The drawings show in:

[0079] FIG. 1a a venous stent schematically in a side view,

[0080] FIG. 1b an end region of a venous stent with so-called “round ends” schematically in a side view,

[0081] FIG. 2 another embodiment of a venous stent schematically in a side view,

[0082] FIG. 3a-3c schematically a positioning system for a venous stent and for other stents, whereas parts of the stent and of the system are presented in perspective views (FIGS. 3a, 3c) and in a front view (FIG. 3b; without stent), and

[0083] FIG. 4 the system for putting in place a stent according to FIGS. 3a-3c in a perspective view,

[0084] FIG. 5 another embodiment of a venous stent schematically in a side view,

[0085] FIG. 6 a table which comprises essential data of stents with different wire thicknesses and varying numbers of strands,

[0086] FIG. 7 a diagram of a factor F for calculation of the number of strands of a stent dependent on the wire diameter D.sub.d, and

[0087] FIG. 8 a diagram which displays the diameter of the stent D in dependency of the length l of rhombuses of the stent.

[0088] A stent 1 has a supporting member 2 for splinting a vein. The stent 1 can exclusively consist of the supporting member 2. Yet, it is also possible that at the supporting member 2 further functional parts, such as e.g. filters or similar, are provided which do not have a supporting function.

[0089] The supporting member 2 is braided from one or more wires 3. Each one of the wires 3 forms one or more strands 4, whereas each strand extends from a proximal end 5 of the stent 1 to a distal end 6 of a stent 1. Within the herewith formed braid the respective strands 4 cross each other pairwise, whereby rhombuses 7 are delimited by the strands 4.

[0090] Such a braided stent 1 has a significantly higher resiliency and elasticity in comparison to common stents cut from tube sections.

[0091] The wires 3 preferably consist of metal, particularly a shape memory metal. The preferred material is nitinol. Generally also other materials such as steel or stiff, in particular fiber-reinforced polymers can be used.

[0092] The stent preferably is provided with so-called “round ends” 8 at one end and particularly at both ends (FIG. 1b). The round ends are formed by bending of a wire 3 into several strands 4, whereby the wire in the region of bending has an about circular segment shaped form and is not kinked. The ends of the wires may also be pairwise welded or crimped together so that the wire forms an endless loop. The connection point may be positioned in the region of the round ends 8 but also in the region of the strands 4. By welding or crimping several wire sections can be combined into a single endless wire.

[0093] In the embodiment shown in FIG. 1a the stent 1 is formed from 16 wires 3 which each are bent into two strands 4. The stent thereby provides 32 strands 4. At the distal end 6 both strands 4 of each wire 3 are twisted together into a twisted section 9 and each forms a loop 10 with their end-standing wire section.

[0094] The loops 10 as well as the round ends 8 provide an atraumatic ending.

[0095] At the proximal end 5 the free ends of two strands 4 are twisted together to form another twisted section 11. In the twisted section 11 the strands 4 or the wires 3, resp., can be soldered together.

[0096] The twisted sections 9 and 11 pairwise fixate the strands 4 respective to their axial movability. Hereby the stiffness in the end region of the stent 1 is increased.

[0097] The stent 1 provides at the proximal end 5 as well as at the distal end 6 each a widened region 12, 13. A main section 14 extending between the widened regions 12, 13 provides in unloaded state an essentially constant diameter. The diameter of the main section 14 in unloaded state typically is 10 to 20 mm. The rhombuses 7 of the main section 14 in longitudinal direction 15 are not shorter than in transversal direction 16 and preferably they are longer in longitudinal direction 15 than in transversal direction 16.

[0098] The longitudinal extension of the rhombuses in unloaded state preferably is at least 10% and in particular 20% greater than the transversal extension.

[0099] The diameter D.sub.s of the stent is described by the following formula:

[00001]$D_s=\frac{n}{\pi }.Math.\sqrt{4-l^2},$

[0100] Wherein n is the number of rhombuses 7 of the stent across the circumferential direction and l the size of the rhombuses in longitudinal direction 15. In this formula the basis are rhombuses with four equally long side edges whereas the length of a side edge is normalized to “1” so that with this formula the diameter D.sub.s is presented with the “length unit of a side edge”.

[0101] FIG. 8 displays the graphs of this function for n=12, n=10 and n=8, resp. For a length l of the rhombuses of √2 (=1.4142) the length of the rhombus is identical to its height. Then it is a square rhombus. One can detect in these graphs that the change of the length of the rhombus in relation to the change of the diameter of the stent is lower if the rhombuses have a length at least as great as their height.

[0102] If the height, however, is greater, then a small changing in the diameter of the stent effects a large change in its length.

[0103] A braided stent 1 whose majority of rhombuses is at least as long as high during squeezing is much less elongated than a stent whose majority of rhombuses has a greater transversal extension than longitudinal extension. By this shape of the rhombuses it is ensured that the entire increase in length of the stent is rather small, even if these are in total very long (e.g. at least 10 cm, or at least 20 cm, or at least 30 cm, resp.).

[0104] Preferably the longitudinal extension of the rhombuses 7 of the main section 14 in unloaded state is not greater than the 1.5 fold of the transversal extension, and preferably not greater than the 1.4 fold, or the 1.3 fold, resp., of the transversal extension. Herewith it is ensured that the stent provides sufficient compression stability. The compression stability amongst others is determined by the rhombus shape, wherein stents with highly longitudinally elongated rhombuses provide a significantly lower compression stability than stents with less elongated rhombuses. The compression stability, however, is also determined by additional parameters, in particular the number of strands and the thickness of the wire used.

[0105] The widened regions 12, 13 can be produced amongst other means by squeezing of the respective section of the stent. Hereby the rhombuses are squeezed a bit in longitudinal direction 15 and elongated a bit in transversal direction 16. This leads to that the diameter of the stent 1 is increased in the widened regions 12, 13 as compared to the main section 14. In addition the widened regions 12, 13 provide a higher compression stability than the main section 14, due to their rhombuses 7 being more elongated in transversal direction. Such a stent is preferably manufactured from a shape memory metal, whereas the stent is fixated in its shape after braiding with a first heat treatment, wherein the stent 1 is held with a constant diameter over its entire length which corresponds to the diameter of the stent in the region of the main section 14. By this heat treatment the material structure in the wire is set so that the stent maintains the “relaxed state” without internal tensions. Subsequently the end regions of the stent are squeezed a bit so that the widened regions 12, 13 are formed. In this condition the stent is heat treated for a second time so that the widened sections 12, 13 are relaxed and maintain this shape. Due to the greater transversal expansion of the rhombuses in the widened region 12, 13 here a greater relative longitudinal extension than in the main section 14 is caused during compression of the stent. As these widened regions 12, 13 in comparison to the other parts of the stent are very short (e.g. 5 mm to 3 cm) the elongation caused by them is low and can be neglected.

[0106] Due to the rhombuses 7 more elongated in transversal direction 16 the widened regions 12, 13 provide a high radial stability.

[0107] The widened regions 12, 13 serve for fixation of the position of the stent in the body vessel, in particular in a vein.

[0108] The stent may also be provided with a decoupling section 17 in which each two strands 4 are twisted together to further twisted sections 18 (FIG. 2). This decoupling section 17 decouples the two braided sections neighboring the decoupling section 17 in radial direction so that the two braided sections can be provided with different diameters without causing tensions in the stent. The twisted sections 18 can proceed to radial outside or to radial inside without hereby tensions or at least no significant tensions are caused. Another effect of this decoupling section 17 is that the strands 4 are pairwise fixated in longitudinal direction 15. Hereby a relative movement of the strands 4 in longitudinal direction is prevented.

[0109] A stent 1 may be provided with no, one or more such decoupling sections 17.

[0110] The stent 1 can be provided with varying diameters (10 mm-20 mm) with varying wire thicknesses (0.05 mm-0.35 mm). Dependent from the wire strength or wire thickness, resp., and the diameter of the respective stent the stent has to be designed with a varying number of strands 4. The table shown in FIG. 6 comprises the data for the wire diameter D.sub.d, the stent diameter D.sub.s, and a factor F for calculation of the number of strands of a stent. The stent has the same number of strands with the other slope in order to delimit one rhombus 7 by each two pairs of strands with differing slope. The number of strands n results from multiplication of the wire diameter D.sub.d with the stent diameter D.sub.s and the factor F. The resulting calculated value has to be rounded up or down, resp., to an integer. The factor F is a function dependent from the wire diameter D.sub.d. In the table ranges with the respective suitable number of strands n are provided. The actually suitable number of strands varies by about ±2 strands around the calculated value. In the present example of an embodiment each one of the wires 3 forms two strands 4. Therefore, all stents 1 have an even number of strands.

[0111] The more strands that are provided, the higher the compression stability of the stent is. However, there are other influences on the compression stability of the stent such as e.g. the shape of the rhombuses and the actually used material of the wires. The data shown in FIG. 6 apply for nitinol wires.

[0112] The factor F dependent from the wire diameter D.sub.d can be described by the following spline functions:

(for 0.05≦D.sub.d≦0.08)

F=91.64+44.35 D.sub.d−20553.34 D.sub.d.sup.2+137022.25 D.sub.d.sup.3   Polynomial 1:

(for 0.08<D.sub.d≦0.1)

F=255.59+−6103.93 D.sub.d+56300.07 D.sub.d.sup.2−183200.28 D.sub.d.sup.3   Polynomial 2:

(for 0.1<D.sub.d≦0.12)

F=54.05+−90.64 D.sub.d−3668.35 D.sub.d.sup.2+16694.46 D.sub.d.sup.3   Polynomial 3:

(for 0.12<D.sub.d≦0.15)

F=113.30+−1576.24 D.sub.d+8730.26 D.sub.d.sup.2−17746.13 D.sub.d.sup.3   Polynomial 4:

(for 0.15<D.sub.d≦0.18)

F=38.95+−79.93 D.sub.d−1276.36 D.sub.d.sup.2+4490.79 D.sub.d.sup.3   Polynomial 5:

(for 0.18<D.sub.d≦0.2)

F=193.93+−2660.39 D.sub.d+13052.63 D.sub.d.sup.2−22044.37 D.sub.d.sup.3   Polynomial 6:

(for 0.2<D.sub.d≦0.22)

F=−114.94+1969.54 D.sub.d−10089.39 D.sub.d.sup.2+16525.66 D.sub.d.sup.3   Polynomial 7:

(for 0.22<D.sub.d≦0.25)

F=147.58+−1609.72 D.sub.d+6178.66 D.sub.d.sup.2−8122.89 D.sub.d.sup.3   Polynomial 8:

(for 0.25<D.sub.d≦0.3)

F=29.54+−194.24 D.sub.d+518.94 D.sub.d.sup.2−576.60 D.sub.d.sup.3   Polynomial 9:

(for 0.3<D.sub.d≦0.35)

F=110.08+−910.08 D.sub.d+2572.00 D.sup.2−2449,52 D.sup.3   Polynomial 10:

[0113] The individual polynomials 1-10 of the spline functions are also valid separately from each other. The spline functions describe the relationship (see FIG. 7) between the wire thicknesses D.sub.d and the factors F such as they are presented in FIG. 6.

[0114] The constant F is an empirical value which results from a multitude of trials.

[0115] Appropriate stents can also be provided with a tolerance of the factor F of ±30%, in particular ±20%, and preferably only ±10% or ±5%, resp. Such stents are optimized in respect of their elongation properties and compression stability. The longitudinal extension in the main section 14 of the stent in unloaded state is at least as great as the transversal extension of the rhombuses. Preferably the longitudinal extension of the rhombuses 7 in the main section 14 is greater than the transversal extension but not greater than the 1.5 fold of the transversal extension. This stent preferably is provided with the widened regions 12, 13 which enable a good fixation of the stents in the vessel.

[0116] Another embodiment of a venous stent according to the invention provides one or more reinforcement sections 31. Within a reinforcement section the rhombuses 7 in longitudinal direction are shorter than the rhombuses of the other sections of the stent 1. Hereby the other sections are more flexible than the reinforcement sections. These other sections hereinafter are called hinge sections 32.

[0117] The rhombuses 7 of the reinforcement sections 31 may, but must not be longer in transversal direction 16 than the rhombuses of the hinge regions 32.

[0118] The reinforcement sections 31 can be provided with the same diameter as the hinge sections 32. In this case the strands 4 are braided with a greater braiding angle in the region of the reinforcement sections 31 relative to the longitudinal extension or longitudinal direction 15 of the stent 1 than in the hinge regions during manufacturing of the stent. The reinforcement sections 31 can, on the other hand, also have a greater diameter than the other sections of the stent 1. In that case the reinforcement sections 31 can be manufactured, equal to the above described widened sections, by squeezing or compression of the respective sections in longitudinal direction. At the distal and proximal ends 5, 6 of the stent 1 round ends 8, twisted sections 9 and/or loops 10 with or without twisted sections may be provided, just as in the embodiments displayed in FIGS. 1a and 1b.

[0119] The reinforcement sections provide to the stent a high radial stiffness. The hinge sections arranged between the reinforcement sections and whose rhombuses have a greater longitudinal extension than the rhombuses of the reinforcement sections 31, however, are softer and more flexible. Preferably reinforcement sections 31 and hinge sections 32 are provided consecutively alternating. The hinge sections 32 typically are double to tenfold as long as the reinforcement sections 32. The alternating arrangement of reinforcement sections 31 and hinge sections 32 thereby forms a type of link chain made from stiff, ring-type reinforcement sections 31 and the more bendable hinge sections 32. Such a venous stent 1 can adapt to any desired curves of the vein. The reinforcement sections 31 prevent that the vein may collapse and limit the elongation of the hinge sections.

[0120] As the stent is braided with continuous strands which extend from the distal end to the proximal end 6 it possesses a homogeneous braid structure. The stent thereby provides a high tear resistance in axial direction which is significantly higher than for comparable stents which are laser-cut from a tube.

[0121] For such a venous stent with reinforcement sections 31 and hinge sections 32 the data for determination of the number n of the strands 4 listed in FIG. 6 also apply.

[0122] The reinforcement sections 31 exhibit a higher density of strands 4 than the hinge sections 32. In the reinforcement sections 31 the strands 4 are braided with a higher slope relative to the longitudinal extension of the stent 1.

[0123] Hereinafter the system for putting in place of a stent will be explained.

[0124] This system comprises an implantation catheter 19, a positioning catheter 20, a flexible anchor wire 21 and a latch wire 22. The positioning catheter 20 is arranged movable in the implantation catheter 19 whereby the outer surface of the positioning catheter 20 is in contact with the inner surface of the implantation catheter 19, whereas a sufficient gap is provided therebetween in order to be able to move the positioning catheter 20 within the implantation catheter 19. The implantation catheter 19 has a cylindrical shape. The positioning catheter 20 has a cylindrical outer wall 23 and a concentrically arranged cylindrical inner wall 24, whereas the outer wall 23 and the inner wall 24 are connected with two preferably diametrically opposed arranged ligaments 25, 26. In the region of the inner wall and the outer wall 23 thereby two chambers 27, 28 are provided. The inner wall 24 delimits another chamber or lumen 29 with a circular cross-section. The anchor wire 21 is threaded through the first of the outer chambers 27 and extends through the loops or the openings of the braid, resp., in the proximal end region of the stent 1, and is threaded from the stent 1 inwards to the latch wire 22 by loops 30 positioned at the end. The latch wire 22 is embraced by the loops 30 of the anchor wire 21. The latch wire extends across the second outer chamber 28. The latch wire 22 as well as the anchor wire 21 extend to the outside of the positioning catheter 20 and the implantation catheter 19 and can be handled by an operator. By pulling the anchor wire 21 a tensile force can be applied to the stent 1 pulling in proximal direction of the stent 1. Herewith during a rearward movement it can be ensured that the stent 1 is attaches concisely with its proximal end 5 at the positioning catheter 20. Once the latch wire 22 is pulled out of the loops 30 of the anchor wire 21 the anchor wire with its loops 30 is free and can be pulled out of the loops or openings, resp., of the stent 1. Hereby the connection between the anchor wire 21 and the stent 1 can be disengaged and the stent 1 be deployed. Also two or more anchor wires can be provided.

[0125] During putting in place of the stent 1 in a blood vessel the stent 1 initially is located in compressed state in the implantation catheter 19. The stent 1 in that situation is arranged in the region of the distal end of the implantation catheter 19 and attaches to the inner surface of the implantation catheter 19. The positioning catheter 20 attaches concisely to the proximal end of the stent 1 and extends across the implantation catheter 19 to the proximal end of the implantation catheter 19.

[0126] The anchor wire 21 in the region of the loops 30 is secured via the latch wire 22. The anchor wire 21 and the latch wire 22 are led out of the positioning catheter 20 and the implantation catheter 21 at their proximal ends. This unit, consisting of the implantation catheter 19, the positioning catheter 20, the anchor wire 21, the latch wire 22 and the stent 1 is inserted into the blood vessel until it is positioned at the intended place.

[0127] The inner chamber or lumen 29 of the positioning catheter 20 serves for accommodating the guidewire (not shown) which initially is inserted until reaching the desired position in the blood vessel and for guiding this catheter arrangement during insertion into the blood vessel. By providing separate chambers 27, 28, 29 the guidewire, the anchor wire 21 and the latch wire 22 can be threaded separately from each other through the positioning catheter 20.

[0128] Once the catheter arrangement is inserted so far into the blood vessel that the stent is located at the desired position then first the guidewire can be removed. Subsequently the implantation catheter 19 is retracted a bit whereas the positioning catheter 20 maintains its position. Thereby it is ensured that the stent 1 is not retracted together with the implantation catheter 19 as it attaches to the front side of the positioning catheter 20. The stent 1 is released from the implantation catheter 19. After deployment of the stent 1 preferably the position of the stent 1 is examined. If it is correct then the latch wire 22 is retracted and the locking of the anchor wire 21 is released. Then the anchor wire can be released from the stent 1 whereby the stent is fully released. Should the position of the stent 1 not be correct then it is possible to push the implantation catheter 19 back over the stent, as long as the anchor wire 21 is locked, and to reposition the stent 1.

[0129] Through the lumen 29 also a balloon catheter can be advanced in order to particularly expand sections of the stent 1. This may be especially useful for the widened regions 12, 13 at the ends which are pressed back into the vessels by a locally limited dilation, in order to immobilize the stent in this way.

[0130] If the stent 1 is put in place correctly then first the anchor wire 21, the latch wire 22, and the positioning catheter 20 are fully retracted from the blood vessel. Lastly the implantation catheter 19 is pulled out.

LIST OF REFERENCE NUMBERS

[0131] 1 Stent [0132] 2 Supporting body [0133] 3 Wire [0134] 4 Strand [0135] 5 Proximal end [0136] 6 Distal end [0137] 7 Rhombus [0138] 8 Round end [0139] 9 Twisted section [0140] 10 Loop [0141] 11 Twisted section [0142] 12 Widened region [0143] 13 Widened region [0144] 14 Main section [0145] 15 Longitudinal direction [0146] 16 Transversal direction [0147] 17 Decoupling section [0148] 18 Twisted section [0149] 19 Implantation catheter [0150] 20 Positioning catheter [0151] 21 Anchor wire [0152] 22 Latch wire [0153] 23 Outer wall [0154] 24 Inner wall [0155] 25 Ligament [0156] 26 Ligament [0157] 27 First chamber [0158] 28 Second chamber [0159] 29 Chamber/Lumen [0160] 30 Loop [0161] 31 Reinforcement section [0162] 32 Hinge section