DE102016107791A1 - Stent and stent delivery system - Google Patents

Abstract

The invention relates to a stent having a substantially tubular grid mesh (10) of a single wire (11) comprising a core material and a cladding material, the core material having a higher X-ray visibility than the cladding material. The invention is characterized in that between 20 vol% and 40 vol%, in particular between 25 vol% and 35 vol%, preferably 27 vol%, of the wire (11) are formed by the core material and a, in particular polished, outer surface of the Wire (11), in particular of the cladding material, comprises a mixed oxide layer comprising TiO 2 and at least one nitride, in particular titanium oxynitride and / or titanium nitride.

Description

The invention relates to a stent according to the preamble of claim 1. Furthermore, the invention relates to a stent delivery system with such a stent. A stent of the type mentioned is, for example WO 2009/089218 A2 known.

The prior art stent comprises a substantially tubular grid mesh formed from a single wire. The wire is made of a composite material, with a core material having a higher radiopacity than a cladding material of the wire. In the known stent, however, there is a risk that breaks through the composite material of the wire at high curvature of the stent, for example when used in a correspondingly curved blood vessel, the core material or the sheath material is overstretched. This can entail disadvantages in terms of the biocompatibility of the known stent.

The object of the invention is to specify a stent which, in addition to increased radiopacity, tolerates a high flexural flexibility. It is another object of the invention to provide a stent delivery system with such a stent.

According to the invention, this object is achieved with respect to the stent by the subject-matter of claim 1 and with respect to the stent delivery system by the subject-matter of claim 6. Specifically, the invention proposes a stent having a substantially tubular mesh of a single wire. The single wire comprises a core material and a cladding material, the core material having higher radiopacity than the cladding material. In this case, between 20 vol% and 40 vol%, in particular between 25 vol% and 35 vol%, preferably 27 vol%, of the wire formed by the core material. It is further provided that a, in particular polished, outer surface of the wire, preferably an outer surface of the jacket material, comprises a mixed oxide layer. The mixed oxide layer may comprise titanium oxide (TiO ₂ ) and at least one nitrite, in particular titanium oxynitride and / or titanium nitrite.

It has surprisingly been found that by a certain percentage distribution of the core material with respect to the shell material based on their volume fraction leads to improved flexural flexibility, without significantly affecting the radiopaque properties. In other words, the stent with the proposed distribution between radiopaque core material and enveloping sheath material is well suited to be guided into highly curved blood vessels without causing damage or cracking in the core material or sheath material. The composite wire formed with the proposed volume ratio has improved stability in this respect.

The oxide layer formed on the outer wire surface, in particular on the outer surface of the cladding material, is characterized by an increased layer hardness. In particular, by the nitrite contained in the mixed oxide layer, an increased layer hardness is provided, whereby the wear of the stent is reduced in the vessel. The proposed mixed oxide layer also reduces the coefficient of friction of the outer surface of the wire, thereby improving the sliding behavior of the stent within a catheter. The good sliding properties also act between the intersecting wires, which in turn has a positive effect on the crimpability of the stent and avoids a rubbing off of the wires sliding off one another.

The wire may have a diameter between 30 μm and 80 μm, in particular between 40 μm and 70 μm, preferably 50 μm.

In combination with the volume ratio between the core material and the jacket material, a wire thickness is provided which, on the one hand, is sufficient for applying a favorable radial force within a blood vessel and, on the other hand, ensures that the stent assumes a comparatively small cross-sectional diameter in the compressed state. The stent can be used so well in small blood vessels, which are numerous in the cerebral area, for example.

The jacket material may have a, in particular shape-memory-capable nickel-titanium alloy. The nickel-titanium alloy is characterized by good biocompatibility. In combination with the mixed oxide layer deposited on the outer surface of the cladding material, particularly the nickel titanium alloy, the biocompatibility is further improved particularly in view of the corrosion resistance because the mixed oxide layer is low in nickel. The shape memory properties improve the operation of the stent and thus the release of the stent in a blood vessel.

The only wire from which the grid mesh is formed, may have two wire ends which are interconnected in a central portion of the grid mesh by a connecting sleeve. The connecting sleeve is preferably formed radiopaque. Preferably, the connection sleeve is a crimp sleeve, so that the two free wire ends are crimped. Such a connection of the wire ends reduces the risk of injury within a Blood vessel, wherein the connecting sleeve can act simultaneously as an additional radiopaque marker. For example, the X-ray-visible connection sleeve can be used to place the stent correctly in the region of an aneurysm. For this purpose, only the radiopaque marker element is to be positioned at the level of the aneurysm neck.

It is possible that the single wire from which the grid mesh is formed forms wire sections extending from one axial longitudinal end to another axial longitudinal end of the grid mesh, which are guided adjacent to one another. In this respect, double wire sections or pairs of wire sections can show up in the grid mesh. In particular, it can be provided that the single wire forms end loops at the axial longitudinal ends of the mesh braid, wherein the latter is guided twice through the end loops. In other words, parallel sections form a double loop. The use of double wire sections or wire section pairs increases the stability and radial force of the grid mesh.

In a preferred embodiment of the invention can also be provided that in addition to the wire ends of the single wire connecting sleeve additional X-ray markers are integrated into the grid. In particular, additional X-ray markers made of a radiopaque material may be arranged in the region of the end loops or double loops at the axial longitudinal ends of the lattice braid. The x-ray markers can be designed as cylindrical full sleeves.

Alternatively, the X-ray makers may be formed as radiopaque, helical, in particular helical spring-like, wire elements, which are preferably arranged in the region of the end loops or double loops. Such wire elements are also referred to as coils. The advantage of X-ray-visible coils is their bending flexibility. This allows the X-ray visible coil to adapt well to the curved shape of the respective end loops or double loop. In particular, the coil can extend so well over a vertex of the end loops or double loop. In any case, the parallel, in particular touching, wire sections can be held together by the sleeve or the coil.

Preferably, the grid mesh has at each axial longitudinal end between one and four, in particular two or three, additional X-ray markers.

The grid mesh preferably has two axial longitudinal ends, which are widened in a funnel shape at least in an expanded state of the grid mesh. Such a design of the stand is particularly suitable for the treatment of aneurysms, wherein the funnel-shaped widened longitudinal ends allow an improved anchoring of the stent in the adjacent to an aneurysm vessel sections. It is particularly preferred if the funnel-shaped expansion encloses an angle which has between 10 ° and 40 °, in particular between 20 ° and 30 °. The angle is preferably determined between the lateral surface of the funnel-shaped expansion and a cylinder jacket surface of a middle region of the stent.

With regard to an improved adaptation of the stent, in particular of the mesh, to the vessel wall in a blood vessel, it is advantageous if the funnel-shaped expansion encloses an angle which is between 50 ° and 80 °, in particular between 60 ° and 70 °.

A subsidiary aspect of the invention relates to a stent delivery system with a previously described stent. The stent delivery system further includes a catheter tube and a transport wire slidably disposed within the catheter tube. The transport wire has at least two sleeves spaced apart from one another and defining a clearance, the clearance receiving an end loop of the stent such that a longitudinal axial pushing and / or pulling force is transferable to the stent through the sleeves. At least one of the sleeves, in particular a sleeve arranged distally with respect to the other sleeve, can be designed as a so-called crown sleeve. The crown sleeve has one or more radially outwardly projecting projections, which preferably engage in the meshes of the mesh to allow the stent to be pulled through the catheter tube in both the proximal and distal directions.

The transport wire with the two sleeves, which limit the free space, contributes to the fact that the entire stent delivery system has a comparatively small cross-sectional diameter and allows the delivery of the stent into small and, if necessary, strongly tortuous blood vessels. The stent delivery system is therefore particularly suitable for use in cerebral blood vessels. The good miniaturization of the stent delivery system results from the fact that the end loops of the stent can be inserted between the two sleeves of the transport wire so as to be able to use the transport wire to push the stent back and forth within the catheter. The possibility of transmitting a tensile force to the stent also ensures that the stent can be withdrawn from the catheter tube and repositioned after partial release.

In order to further facilitate the delivery of the stent into highly tortuous blood vessels, it is provided in a preferred variant of the stent delivery system that the transport wire has an angled and / or flexible tip. The angled tip can be aligned by rotation of the transport wire, so that it is also possible to penetrate with the transport wire in branching blood vessels.

The invention is explained in more detail below with reference to an embodiment with reference to the accompanying schematic drawings.

Show:

1 a side view of a stent according to the invention according to a preferred embodiment in the manufacturing state; and

2 a detailed view of the stent according to 1 ,

1 shows a stent according to the invention in a side view, wherein the stent is in a manufacturing state. Specifically, the stent is on a thorn 18 arranged. The thorn 18 forms a braid base or substrate for braiding the mesh 10 ,

The grid 10 is made of a single wire 11 formed helically around the longitudinal axis of the mandrel 18 is winding. The wire 11 is several times at the longitudinal ends 15 . 16 of the lattice braid 10 deflected and forms there end loops 17 , Here is the wire 11 arranged or aligned so that its wire ends 12 . 13 in a central region of the grid 10 are positioned. The wire ends 12 . 13 are through a connecting sleeve 14 , which is preferably designed as a crimp sleeve connected. The connection sleeve 14 preferably has a radiopaque material and forms a central x-ray marker.

The only wire 11 comprises a composite material comprising in particular a radiopaque core material and a biocompatible sheath material. The core material is preferably platinum. About 27 vol% of the wire 11 are taken up by the nuclear material. The remaining 65 vol% to 73 vol% of the wire material are preferably formed by the cladding material. The jacket material comprises in particular a nickel-titanium alloy or consists thereof. On an outer surface of the wire 11 or the nickel-titanium alloy, a mixed oxide layer of titanium oxide and nitride, in particular titanium nitride or titanium oxynitride, applied. The mixed oxide layer provides a bluish shimmering outer surface, giving the stent a unique coloration.

As in 1 Furthermore, it can be seen, have the longitudinal axial ends 15 . 16 of the stent or the mesh braid 10 a funnel-shaped expansion on. The funnel-shaped expansion preferably comprises a funnel angle of 40 °. The funnel angle is starting from the outer surface of the mandrel 18 determined.

2 shows the connection of the wire ends 12 . 13 in detail. It can be seen that the radiopaque sleeve 14 both wire ends 12 . 13 absorbs, at least within the connecting sleeve 14 parallel next to each other. The connection sleeve 14 encloses both wire ends 12 . 13 and fixes them with a crimp connection.

The outer surface of the wire 11 is preferably polished. Before polishing, the wire includes 11 preferably 20 vol% of the core material. After polishing, in which the cladding material is reduced, the proportion of the core material is preferably about 20 vol%. In this case, a tolerance of 3 vol% is provided. The cross-sectional diameter of the wire 11 is preferably 0.058 mm with a tolerance of 0.003 mm. The transformation temperature of the shape memory wire 11 is preferably between 10 ° C and 18 ° C.

The aforementioned values for the cross-sectional diameter of the wire 11 especially concern the unpolished state of the wire 11 , Then, the cross-sectional diameter is preferably 0.058 mm. After polishing, the wire can 11 have a cross-sectional diameter of 0.050 mm, with a tolerance of 0.003 mm is common.

The braiding angle of the grid 10 that is the angle between the wire 11 and a longitudinal axis of the mesh braid 10 in the manufacturing state is preferably 65 °, with a tolerance of 2 ° is possible.

The stent is preferably dimensioned such that it is insertable via a catheter tube into a blood vessel having a size of 2 French (about 0.67 mm in cross-sectional diameter).

Within the catheter tube, a transport wire is slidably mounted, which carries two sleeves, which define a free space between them. The free space is preferably dimensioned such that in the free space end loops 17 of the stent can be inserted. The end loops 17 can thus come into contact with both sleeves of the transport wire, whereby a pulling or pushing force can be applied to the stent. Preferably, one or more proximal end loops 17 of the stent disposed in the space between the sleeves, so that after partial deployment of the stent from the catheter tube, the stent can be withdrawn and repositioned.

LIST OF REFERENCE NUMBERS

10

wickerwork

11

wire

12, 13

wire end

14

connecting sleeve

15, 16

longitudinal end

17

end loop

18

mandrel

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2009/089218 A2 [0001]

Claims (7)

Stent with a substantially tubular mesh ( 10 ) from a single wire ( 11 ) having a core material and a cladding material, wherein the core material has a higher roughness visibility than the cladding material, characterized in that between 20 vol% and 40 vol%, in particular between 25 vol% and 35 vol%, preferably 27 vol%, of Wire ( 11 ) are formed by the core material and a, in particular polished, outer surface of the wire ( 11 ), in particular of the cladding material, comprises a mixed oxide layer comprising TiO ₂ and at least one nitride, in particular titanium oxynitride and / or titanium nitride. Stent according to claim 1, characterized in that the wire has a diameter between 30μm and 80μm, in particular between 40μm and 70μm, preferably 50μm. Stent according to claim 1 or 2, characterized in that the jacket material has a, in particular shape memory, nickel-titanium alloy. Stent according to one of the preceding claims, characterized in that the single wire ( 11 ) two wire ends ( 12 . 13 ), which in a central portion of the mesh ( 10 ) by a, in particular radiopaque, connection sleeve ( 14 ), in particular crimped, are. Stent according to one of the preceding claims, characterized in that the mesh ( 10 ) two axial longitudinal ends ( 15 . 16 ), which at least in an expanded state of the mesh ( 10 ) are widened funnel-shaped. A stent delivery system comprising a stent as claimed in any one of the preceding claims, a catheter tube and a transport wire slidably disposed within the catheter tube having at least two sleeves spaced apart and defining a clearance, the clearance defining an end loop (US Pat. 17 ) of the stent so that a longitudinal axial pushing and / or pulling force on the stent is transferable through the sleeves. Stent delivery system according to claim 6, characterized in that the transport wire has an angled and / or flexible tip.

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