Stent

Abstract

The invention relates to a stent with a self-expandable, tubular braided structure (10) of meshes (11), wherein the braided structure (10) is formed by at least one wire (12), in particular a single wire (12), of an x-ray-visible core material and a sheathing material and both ends (13) of the braided structure (10) have closed loops (14a, 14b), wherein - the braided structure (10) has at least one marker element (15), which is arranged between the two ends (13), in particular centrally with respect to the braided structure (10), and - the braided structure (10) has in the rest state a diameter of between 7 and 12 mm.

Description

[0001] Stent

[0002] Description

[0003] The invention relates to a stent with a self-expanding, tubular mesh structure made of meshes. The mesh structure is formed by at least one wire, in particular a single wire, made of an X-ray-visible core material and a sheath material, and both ends of the mesh structure have closed loops. A stent according to the preamble of claim 1 is known, for example, from DE 102018125983 A1.

[0004] Stents are commonly used to treat vascular disorders such as stenosis and / or aneurysms. Stents can be used to widen narrowed blood vessels in the area of ​​a stenosis to ensure adequate blood flow. In the treatment of aneurysms, a stent is used to reduce blood flow into the aneurysm, allowing the blood in the aneurysm to coagulate. For correct stent positioning, it is important that the stent is clearly visible under X-ray control.

[0005] DE 102018125983 A1, mentioned above, discloses a stent with a self-expanding, tubular mesh structure. This stent is designed for specific applications, such as the treatment of intracranial aneurysms.

[0006] The invention is based on the object of providing a stent for the treatment of vascular diseases whose field of application is expanded.

[0007] According to the invention, this object is achieved by a stent having the features of claim 1. Specifically, this object is achieved by a stent with a self-expanding, tubular mesh structure. The mesh structure is formed by at least one wire, in particular a single wire, made of an X-ray-visible core material and a sheath material, and both ends of the mesh structure have closed loops. The mesh structure has at least one marker element arranged between the two ends, in particular centrally relative to the mesh structure. The mesh structure has a diameter of between 7 and 12 mm in the resting state.

[0008] The invention has the advantage that the arrangement of at least one marker element between the two ends, particularly centrally relative to the mesh structure, ensures optimal X-ray visibility of the stent. This allows for ideal positioning of the stent, particularly the center of the stent, in the region of an aneurysm and / or stenosis. This arrangement of a marker element makes it easy for a surgeon to estimate where the stent will be placed in the vessel after being released from an introducer.

[0009] The invention further has the advantage that the mesh structure has a diameter of between 7 and 12 mm in its resting state, making the stent suitable for a wide range of applications. In particular, the stent is ideally suited for use in vessels with a diameter comparable to the basilar artery or the internal carotid artery.

[0010] Preferred embodiments of the invention are specified in the subclaims.

[0011] Preferably, the closed loops form an enlarged diameter of the braided structure with a flaring angle b relative to a central longitudinal axis M of the braided structure. Such a radial expansion of the axial ends can, for example, prevent the risk of stent migration.

[0012] Furthermore, the flaring angle b is preferably approximately 45°. It should be noted that a specific flaring angle is advantageous for a specific stent diameter range. A flaring angle b of approximately 45° is therefore particularly advantageous for a stent with a resting diameter between 7 and 12 mm, as the opening behavior of the stent is positively influenced. A further advantage is that the normal forces between the wires are kept low by a flaring angle b = approximately 45°. This can reduce or prevent material abrasion, which has a positive effect on the braid stability and can reduce the risk of fatigue fracture. Furthermore, the deliverability of the stent is improved due to lower radial forces in the flaring area.

[0013] The flaring angle b is generally measured in the resting state, i.e., when no external forces act on the stent, between the central axis M of the tubular braided structure and a loop of the expanded axial end. The flaring angle b can be understood as a conical or tapered opening angle.

[0014] In a preferred embodiment, the marker element can comprise a marker sleeve that is firmly connected to the wire, in particular, crimped onto the wire. Such marker sleeves, for example, have a higher radiopacity than marker coils, resulting in improved radiopacity. The marker sleeves are attached to the wire of the stent, in particular, by crimping. This allows a stable connection between the marker sleeve and the wire to be achieved.

[0015] More preferably, the wire can have two wire ends that are firmly connected to each other by the marker element. The marker element can thus serve to connect the free ends of the wire to each other, ensuring the stability of the braided structure. The marker element also serves to ensure good radiopacity of the stent.

[0016] Furthermore, it is preferred that the meshes be arranged in rings extending in the circumferential direction of the mesh structure, wherein the rings can each have 6 to 14 meshes, in particular 12 to 14 meshes. This achieves good stability of the mesh structure, especially for stent diameters in the resting state between 7 and 12 mm.

[0017] The loops can preferably form large and small loops, with a small loop having a length of 57% to 81% of the length of a large loop. This means that the loops of the axial end are advantageously designed differently, in particular of different lengths. This makes it possible to improve the expansion properties of the stent in the region of the axial ends by specifically adjusting the design of individual loops, in particular the length of the loops. Furthermore, the relative movement between intersecting wires or the interaction between the wires can be reduced, thereby reducing material abrasion and consequently the risk of fatigue fracture. The terms "large loops" and "small loops" are generally understood to mean that the large loops of an axial end of the braided structure are larger than the small loops of the same axial end.Preferably, the large loops of one axial end are of the same size. The same applies to the small loops. In other words, all large loops or all small loops are advantageously of the same length.

[0018] More preferably, the wire has a diameter between 60 and 120 μm. These wire diameters favorably influence the radial force of the stent, thereby achieving optimal expansion and compression behavior.

[0019] In a further preferred embodiment, the core material of the wire can comprise platinum or a platinum alloy. The wire has a platinum content of <20% for a diameter of >85 pm, and a platinum content of >20% for a diameter of <85 pm. In particular, the wire has a platinum content of 30% for a diameter of 50 pm to 70 pm. This platinum content in the core material of the stent enables good X-ray visibility of the wires themselves.

[0020] The platinum content generally describes the volume fraction of platinum relative to the cross-sectional area of ​​the wire.

[0021] The invention is explained in more detail using an embodiment in conjunction with the schematic drawing.

[0022] In this, Fig. 1 shows an embodiment of a stent according to the invention with a self-expanding, tubular mesh structure.

[0023] Figure 1 shows an embodiment of a stent according to the invention with a self-expanding, tubular mesh structure 10. This stent is used for the treatment of intracranial aneurysms, particularly in the basilar artery or the internal carotid artery. The use of the stent in other vessels of comparable diameter is conceivable. Furthermore, other applications, such as the treatment of stenoses, are possible.

[0024] As shown in Figure 1, the mesh structure 10 of the stent is formed from meshes 11. The meshes 11 form circumferential segments that continue in the axial direction of the mesh structure 10.

[0025] The stent according to Fig. 1 is also a single-wire stent, which is formed from or consists of a single wire 12. The wire 12 is braided in such a way that the mesh shape shown in Fig. 1 is created. It is also possible for the stent to be formed from or consist of multiple wires 12.

[0026] The wire 12 of the braided structure 10 shown in Figure 1 is formed from an X-ray-visible core material encased in a sheath material. The sheath material can be, for example, a nickel-titanium alloy such as Nitinol or another biocompatible alloy. Such wires are known, for example, as DFT wires.

[0027] Figure 1 further shows that the two ends of the braided structure 13 form closed loops 14a, 14b, which delimit the braided structure 10 in the axial direction. The loops differ from the meshes 11 of the braided structure 10 in their size. Thus, it can be seen in Figure 1 that the loops form larger openings than the meshes 11 of the braided structure 10. In the exemplary embodiment according to Figure 1, the meshes 11 have a diamond shape. Figure 1 further shows that the braided structure 10 has a marker element 15, which is arranged between the two ends 13. Specifically, the marker element 15 is arranged centrally with respect to the braided structure 10. It is also possible for the marker element 15 to be arranged off-center with respect to the braided structure 10. Furthermore, the braided structure 10 can have multiple marker elements 15. These multiple marker elements 15 can be arranged centrally or off-center relative to the mesh structure 10.

[0028] The stent according to Figure 1 can have a diameter between 7 mm and 12 mm in the resting state. In particular, the stent can have a diameter of 7 mm, in particular 8 mm, in particular 9 mm, in particular 10 mm, in particular 11 mm, in particular 12 mm in the resting state. These diameters are particularly advantageous for the treatment of vascular diseases of the basilar artery, the internal carotid artery, or vessels with comparable diameters.

[0029] Furthermore, the stent according to Figure 1 can have a length between 30 mm and 60 mm in the axial direction. In particular, the stent can have a length of 30 mm, in particular 40 mm, in particular 50 mm, in particular 60 mm. These lengths are also particularly preferred for the applications mentioned above.

[0030] Figure 1 shows that the closed loops 14a, 14b form an enlargement of the diameter of the braided structure 10 with a flaring angle b relative to the central longitudinal axis M of the braided structure 10. In the specific case, the stent according to Figure 1 has a flaring angle b of approximately 45°. It can be seen that the flaring angle b extends essentially constantly around the central longitudinal axis M and can be conical or tapered. It can also be seen that the diameter of the tubular braided structure 10 is larger in the region of the axial ends 13 than in the central region between the two axial ends of the braided structure 13. The enlargement in diameter occurs continuously, beginning in the region of the meshes 11 and continuously transitioning into the loops 14a, 14b.

[0031] In use, ie, in the implanted state (not shown), the axial ends 13 are stretched or nearly stretched and follow the course of the vessel. As shown in Figure 1, the stent has a marker element 15 with a marker sleeve. The marker sleeve is firmly connected to the wire 12, in particular crimped onto the wire 12. Other attachment methods are conceivable, for example, attachment by gluing or welding.

[0032] The stent according to Figure 1 further comprises two wire ends that are firmly connected to one another by the marker element 15. The marker element 15 connects the wire ends in the center of the braided structure 10 or in the center of the stent. The wire ends can also be connected by the marker element 15 in another area between the ends of the braided structure 13, for example, off-center relative to the braided structure 10. It is also conceivable for multiple wire ends to be connected by multiple marker elements 15.

[0033] Figure 1 further shows that the meshes 11 of the mesh structure 10 are arranged in rings that extend in the circumferential direction of the mesh structure 10. In the exemplary embodiment according to Figure 1, a ring has 12 meshes 11. A different number of meshes 11 per ring is conceivable. For example, the number of meshes 11 per ring can be 6, 7, 8, 9, 10, 11, 13, or 14. A number of meshes 11 of 12 to 14 per ring is particularly preferred.

[0034] Figure 1 shows that the loops at the axial ends of the gel fencing structure 13 form large and small loops 14a, 14b. It can be seen that the length of a large or small loop 14a, 14b extends from the apex of the loop to the next, oppositely arranged wire crossing. In the embodiment shown in Figure 1, the loops are diamond-shaped, with the length of the loops being defined by the longer axis, i.e., the longitudinal axis, of the diamond.

[0035] Fig. 1 also shows that the large and small loops 14a, 14b are arranged alternately in the circumferential direction. This allows for a uniform expansion behavior.

[0036] The stent shown in Figure 1 can be formed from a wire 12 having a diameter between 60 and 120 μm. For the aforementioned application, wire diameters of 60 μm, 70 μm, or 85 μm are particularly preferred. Other wire diameters are also conceivable.

[0037] Furthermore, the stent according to Figure 1 can comprise a wire 12 with a core material made of platinum or a platinum alloy. A specific platinum content is preferred for a specific wire diameter. For a wire diameter > 85 pm, a platinum content of < 20% is preferred. For a wire diameter < 85 pm, a platinum content of > 20% is advantageous. Specifically, a platinum content of 30% is preferred for a wire diameter of 50 pm to 70 pm. It is also conceivable for the core material to be formed from another, X-ray-visible material.

[0038] List of reference symbols

[0039] 10 Braided structure

[0040] 11 stitches

[0041] 12 wire

[0042] 13 ends of the braid structure

[0043] 14a large loops

[0044] 14b small loops

[0045] 15 marker element

Claims

Claims 1. Stent with a self-expanding, tubular mesh structure (10) made of meshes (11), wherein the mesh structure (10) is formed by at least one wire (12), in particular a single wire (12), made of an X-ray visible core material and a sheath material, and both ends (13) of the mesh structure (10) have closed loops (14a, 14b), characterized in that - the braided structure (10) has at least one marker element (15) which is arranged between the two ends (13), in particular centrally relative to the braided structure (10), and - the braided structure (10) has a diameter of between 7 and 12 mm when at rest.

2. Stent according to claim 1, characterized in that the closed loops (14a, 14b) form an enlargement of the diameter of the braided structure (10) with a flaring angle b relative to a central longitudinal axis M of the braided structure (10), where: b = approximately 45°.

3. Stent according to claim 1 or 2, characterized in that the marker element (15) has a marker sleeve which is firmly connected to the wire (12), in particular crimped onto the wire (12).

4. Stent according to one of the preceding claims, characterized in that the wire (12) has two wire ends which are firmly connected to one another by the marker element (15).

5. Stent according to one of the preceding claims, characterized in that the meshes (11) are arranged in rings which extend in the circumferential direction of the braided structure (10), wherein the rings each have 6 to 14 meshes (11), in particular 12 to 14 meshes (11).

6. Stent according to one of the preceding claims, characterized in that the loops (14a, 14b) form large and small loops (14a, 14b), wherein a small loop (14b) has a length of 57% to 81% of the length of a large loop (14a).

7. Stent according to one of the preceding claims, characterized in that the wire (12) has a diameter between 60 and 120 pm.

8. Stent according to one of the preceding claims, characterized in that the core material of the wire (12) comprises platinum or a platinum alloy, wherein the wire (12) has a platinum content of < 20% for a diameter > 85 pm and a platinum content of > 20% for a diameter < 85 pm, and wherein in particular the wire (12) has a platinum content of 30% for a diameter of 50 pm to 70 pm.

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