stent

Abstract

The present invention relates to a stent having a self-expanding tubular braided structure (10) made of a mesh (11), wherein the braided structure (10) is formed by at least one wire (12), specifically a single wire (12), consisting of an X-ray visible core material and a sheath material, the ends (13) of the braided structure (10) have closed loops (14a, 14b), the braided structure (10) has at least one marker element (15) positioned between the two ends (13), specifically in the center with respect to the braided structure (10), and the diameter of the braided structure (10) in a resting state is 7 to 12 mm.

Description

Technical Field

[0001] The present invention relates to a stent having a self-expanding tubular braided structure formed from a mesh, wherein the braided structure is formed by at least one wire, specifically a single wire, manufactured from a radiopaque core material and a sheath material, and both ends of the braided structure have closed loops. A stent based on the superordinate concept of claim 1 is known, for example, from German Patent Application Publication No. 10 2018 125 983 A1.

Background Art

[0002] Stents are commonly used for the treatment of vascular diseases such as stenosis and / or aneurysms. By using a stent to expand the constricted blood vessel in the stenosis area, sufficient blood flow can be ensured. In the treatment of aneurysms, the blood flow into the aneurysm is reduced by the stent, so the blood located in the aneurysm can coagulate. It is important for the correct positioning of the stent that the stent is clearly visible under radiographic imaging monitoring.

[0003] A stent having a self-expanding tubular braided structure is known from the above-mentioned German Patent Application Publication No. 10 2018 125 983 A1. This known stent is designed for special applications, such as the treatment of intracranial aneurysms.

Summary of the Invention

[0004] The object of the present invention is to provide a stent for the treatment of vascular diseases having a wider range of application fields.

[0005] According to the present invention, this problem is achieved by a stent having the features of claim 1.

[0006] Specifically, this objective is achieved by a stent having a self-expanding tubular braided structure formed from a mesh. The braided structure is formed from at least one wire, specifically a single wire, manufactured from a radiopaque core material and a sheath material, and both ends of the braided structure have closed loops. The braided structure has at least one marker element positioned between the two ends, specifically in the center with respect to the braided structure. The diameter of the braided structure in the non-operated state is 7 to 12 mm.

[0007] An advantage of the present invention is that optimal radiopaqueness of the stent is ensured by positioning at least one marker element between the two ends, specifically in the center with respect to the braided structure. This allows for ideal positioning of the stent, particularly in the center of the stent, within the site of the aneurysm and / or stenosis. Such placement of the marker element facilitates the surgeon's determination of where to position the stent within the blood vessel after it has been released from the introducer.

[0008] Another advantage of the present invention is that the diameter of the braided structure is 7-12 mm in the unoperated state, making the stent suitable for a wide range of applications. Specifically, the stent is ideally suited for use in blood vessels having a diameter equivalent to that of the basilar artery or internal carotid artery.

[0009] Preferred embodiments of the present invention are defined in the dependent claims.

[0010] Preferably, the closed loop forms an enlarged portion of the diameter of the braided structure having a flare angle b with respect to the longitudinal central axis M of the braided structure. By radially widening the axial end of this type in this way, the risk of stent movement can be avoided, for example.

[0011] Furthermore, preferably, the flare angle b = approximately 45°. Note that a particular flare angle is advantageous for a specific diameter range of the stent. Therefore, a flare angle b of approximately 45° is particularly advantageous for stents having an unoperated diameter of 7-12 mm, because this angle has a favorable effect on the stent's opening behavior. A further advantage is that the normal force between the wires is kept low by the flare angle b = approximately 45°. This can reduce or prevent material wear, thereby favorably affecting the stability of the braid and reducing the risk of fatigue fracture. Additionally, the deliverability of the stent is improved due to the lower radial force within the flared region.

[0012] Generally, the flare angle b is measured in the non-operational state, i.e., when no external force is acting on the stent between the central axis M of the tubular braided structure and the loop at the expanded axial end. The flare angle b should be understood as the taper angle or cone angle of the opening.

[0013] In a preferred embodiment, the marker element may have a marker sleeve fixedly coupled to the wire, specifically pressed onto the wire. This type of marker sleeve has a higher X-ray density compared to, for example, a marker coil. This improves radiopaqueness. Specifically, the marker sleeve is attached to the stent wire by pressure bonding. This allows for a stable bond between the marker sleeve and the wire.

[0014] More preferably, the wire may have two wire ends that are fixedly joined to each other by marker elements. As a result, the braided structure remains stable, as the marker elements can help to join the free ends of the wires to each other. The marker elements also help to ensure good radiopaqueness of the stent.

[0015] Furthermore, the mesh is arranged in the form of rings extending circumferentially around the braided structure, and each ring can have 6 to 14 meshes, specifically 12 to 14 meshes. This ensures that the braided structure is stable, specifically for stent diameters of 7 to 12 mm in the non-operational state.

[0016] The loops form large and small loops, with the length of the small loops being 57% to 81% of the length of the large loops. This should be understood as meaning that the loops at the axial ends are advantageously configured to have different conditions, specifically different lengths. This makes it possible to improve the expansion characteristics of the stent in the axial end region by uniquely adjusting the structure of the individual loops, specifically the length of the loops. Furthermore, relative motion between intersecting wires, or interaction between wires, can be reduced, thereby reducing material wear and, consequently, the risk of fatigue fracture. The terms “large loop” and “small loop” should generally be understood as meaning that the large loops at the axial ends of the braided structure are larger than the small loops at the same axial ends. Preferably, the large loops at the axial ends are the same size. The same applies to the small loops. In other words, it is desirable that all large or small loops have advantageously the same length.

[0017] More preferably, the wire diameter is 60 to 120 μm. These wire diameters have a favorable effect on the radial forces of the stent, thereby enabling optimal expansion and compression behavior.

[0018] In a further preferred embodiment, the wire core material comprises platinum or a platinum alloy. In this regard, the wire has a platinum content of ≤20% for diameters ≥85 μm and a platinum content of >20% for diameters <85 μm. Specifically, the wire has a platinum content of 30% for diameters between 50 μm and 70 μm. This platinum content in the stent core material results in good radiopaqueness of the wire itself.

[0019] Platinum content generally represents the volume ratio of platinum to the cross-sectional area of ​​the wire.

[0020] The present invention will be described in detail below, using exemplary embodiments and accompanied by schematic diagrams. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 shows an exemplary embodiment of a stent according to the present invention, which has a self-expanding tubular braided structure formed from a mesh. [Modes for carrying out the invention]

[0022] Figure 1 shows an exemplary embodiment of a stent according to the present invention, having a self-expanding tubular braided structure 10. This specifically relates to the application of the stent to an intracranial artery aneurysm in the basilar artery or internal carotid artery. The use of the stent in other blood vessels of comparable diameter is also conceivable. Furthermore, other applications, such as the treatment of stenosis, are also possible.

[0023] As shown in Figure 1, the braided structure 10 of the stent is formed from a mesh 11. In this regard, the mesh 11 forms circumferential segments that advance in the axial direction of the braided structure 10.

[0024] Furthermore, the stent shown in Figure 1 is a single-wire stent. A single-wire stent is formed from or consists of a single wire 12. The wire 12 is braided to obtain the mesh shape shown in Figure 1. It is also possible for the stent to be formed from or consist of multiple wires 12.

[0025] The wire 12 of the braided structure 10 shown in FIG. 1 is formed from a radiopaque core material. The core material is sheath-shapedly covered by a sheath material. The sheath material may be, for example, a nickel-titanium alloy, such as Nitinol, or another biocompatible alloy. This type of wire is known, for example, as a DFT wire.

[0026] As further shown in FIG. 1, the two ends of the braided structure 13 form closed loops 14a, 14b, and these closed loops axially partition the braided structure 10. The loops are different in size from the mesh 11 of the braided structure 10. Thus, as can be seen from FIG. 1, the loops form an opening larger than the mesh 11 of the braided structure 10. In the exemplary embodiment shown in FIG. 1, the mesh 11 has a rhombus shape.

[0027] As further shown in FIG. 1, the braided structure 10 has a marker element 15 disposed between the two ends 13. Specifically, the marker element 15 is disposed centrally with respect to the braided structure 10. The marker element 15 can also be disposed at a position offset from the center with respect to the braided structure 10. Furthermore, the braided structure 10 can also have a plurality of marker elements 15. Such a plurality of marker elements 15 can be disposed centrally or offset from the center with respect to the braided structure 10.

[0028] The diameter of the stent shown in FIG. 1 is 7 - 12 mm in the non-operating state. Specifically, the diameter of the stent in the non-operating state can be 7 mm, specifically 8 mm, specifically 9 mm, specifically 10 mm, specifically 11 mm, specifically 12 mm. These diameters are particularly advantageous for treating vascular diseases of the basilar artery, internal carotid artery, and blood vessels having equivalent diameters.

[0029] Furthermore, the stent shown in Figure 1 can have an axial length of 30 mm to 60 mm. Specifically, the stent length may be 30 mm, specifically 40 mm, specifically 50 mm, or specifically 60 mm. These lengths are particularly preferred for the applications described above.

[0030] As shown in Figure 1, the closed loops 14a and 14b form an enlarged portion of the diameter of the braided structure 10, having a flare angle b with respect to the longitudinal central axis M of the braided structure 10. In this specific example, the flare angle of the stent shown in Figure 1 is approximately 45°. As can be seen from the figure, the flare angle b is approximately constant around the longitudinal central axis M and can be tapered or conical. Also as can be seen from the figure, 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 13 of the braided structure 13. The diameter expands continuously. The expansion of the diameter begins in the region of the mesh 11 and continues continuously into the loops 14a and 14b.

[0031] During use, i.e., when implanted (not shown), the axial end 13 is elongated or nearly elongated and follows the contour of the blood vessel.

[0032] As can be seen from Figure 1, the stent has a marker element 15 equipped with a marker sleeve. The marker sleeve is fixedly coupled to the wire 12, specifically by being press-fitted onto the wire 12. Other fixing methods, such as adhesive or welding, are also possible.

[0033] Furthermore, the stent shown in Figure 1 has two wire ends that are fixedly joined to each other by marker elements 15. In this regard, the marker elements 15 join the wire ends in the center of the braided structure 10 or in the center of the stent. The wire ends may also be joined by the marker elements 15 in another region between the ends of the braided structure 13, for example, at a position off-center with respect to the braided structure 10. Multiple wire ends can also be joined by multiple marker elements 15.

[0034] As further shown in Figure 1, the mesh 11 of the braided structure 10 is arranged in the form of rings extending circumferentially around the braided structure 10. In the exemplary embodiment shown in Figure 1, each ring has 12 meshes 11. The number of meshes 11 per ring may be other. For example, the number of meshes per ring may be 6, 7, 8, 9, 10, 11, 13, or 14. The number of meshes 11 per ring is particularly preferably 12 to 14.

[0035] Figure 1 shows that the loops at the axial ends of the braided structure 13 form large and small loops 14a and 14b. As can be seen from the figure, the length of the large and small loops 14a and 14b extends from the apex of the loop to the next wire intersection on the opposite side. In the exemplary embodiment shown in Figure 1, the loops are rhombic in shape, and the length of the loops is determined by the long axis of the rhombuse, i.e., the longitudinal axis.

[0036] Figure 1 also shows that large and small loops 14a and 14b are arranged alternately in the circumferential direction. This allows for uniform expansion behavior.

[0037] The stent shown in Figure 1 can be formed from a wire 12 with a diameter of 60 to 120 μm. For the aforementioned applications, wire diameters of 60 μm, 70 μm, or 85 μm are particularly preferred. Other wire diameters are also possible.

[0038] Furthermore, the stent shown in Figure 1 may include a wire 12 having a core material made of platinum or a platinum alloy. In this regard, a specific platinum content is preferred for a particular wire diameter. For wire diameters ≥85 μm, a platinum content of ≤20% is preferred. For wire diameters <85 μm, a platinum content of >20% is advantageous. Specifically, for wire diameters of 50 μm to 70 μm, a platinum content of 30% is preferred. It is also conceivable to form the core material from another radiopaque material. [Explanation of Symbols]

[0039] 10 Braided structure 11 mesh 12 wires 13 Ends of the braided structure 14a Large loop 14b Small loop 15 Marker Elements

Claims

1. A stent having a self-expanding tubular braided structure (10) formed from a mesh (11), wherein the braided structure (10) is formed from at least one wire (12), specifically a single wire (12), manufactured from a radiopaque core material and a sheath material, and the ends (13) of the braided structure (10) have closed loops (14a, 14b), - The braided structure (10) has at least one marker element (15) positioned between the two ends (13), specifically, in the center with respect to the braided structure (10), and - The diameter of the braided structure (10) is 7 to 12 mm in the non-operated state. A stent characterized by the following features.

2. The stent according to claim 1, characterized in that the closed loops (14a, 14b) form an enlarged portion of the diameter of the braided structure (10) having a flare angle b with respect to the longitudinal central axis M of the braided structure (10), and b = approximately 45°.

3. The stent according to claim 1 or 2, characterized in that the marker element (15) has a marker sleeve fixedly coupled to the wire (12), specifically pressed against the wire (12).

4. The stent according to any one of claims 1 to 3, characterized in that the wire (12) has two wire ends that are fixedly connected to each other by the marker element (15).

5. The stent according to any one of claims 1 to 4, characterized in that the mesh (11) is arranged in the form of rings extending in the circumferential direction of the braided structure (10), and each ring has 6 to 14 meshes (11), specifically 12 to 14 meshes (11).

6. The stent according to any one of claims 1 to 5, characterized in that the loops (14a, 14b) form a large loop and a small loop (14a, 14b), and the length of the small loop (14b) is 57% to 81% of the length of the large loop (14a).

7. The stent according to any one of claims 1 to 6, characterized in that the diameter of the wire (12) is 60 to 120 μm.

8. A stent according to any one of claims 1 to 7, characterized in that the core material of the wire (12) contains platinum or a platinum alloy, the wire (12) has a platinum content of ≤20% for diameters ≥85 μm and a platinum content of >20% for diameters <85 μm, and specifically, the wire (12) has a platinum content of 30% for diameters from 50 μm to 70 μm.

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