EP4076274A1

EP4076274A1 - Medical system for treating stenosis in intracranial vessels

Info

Publication number: EP4076274A1
Application number: EP20837929.7A
Authority: EP
Inventors: Michael BÜCHERT; Giorgio Cattaneo
Original assignee: Acandis GmbH and Co KG
Current assignee: Acandis GmbH and Co KG
Priority date: 2019-12-20
Filing date: 2020-12-10
Publication date: 2022-10-26
Also published as: US20230132863A1; DE102019135498B4; DE102019135498A1; CN114901209A; WO2021122251A1

Abstract

The invention relates to a medical system for treating stenosis in intracranial blood vessels, comprising - a compressible and self-expandable implant (1) for covering the stenosis, said implant having a lattice structure (10), at least some sections of which are provided with a cover (40) made of an electrospun fabric, wherein the fabric has irregularly sized pores (41), and - a balloon catheter (60) for dilating the stenosis and/or introducing the implant (1) into the blood vessel.

Description

Medical system for the treatment of stenoses in intracranial vessels

DESCRIPTION

The invention relates to a medical system for treating stenoses in intracranial vessels with a stent and a balloon catheter.

WO 2014/177634 A1 describes a highly flexible stent which is suitable for supporting blood vessels and has a compressible and expandable lattice structure, the lattice structure being designed in one piece. The lattice structure comprises closed cells which are each delimited by four lattice elements. The lattice structure has at least one cell ring which comprises between three and six cells.

In addition, stents with lattice structures which are formed from a single wire are known from the applicant's practice. The wire is intertwined with itself to form a tubular braid. The wire is deflected at the axial ends of the tubular braid so that atraumatic loops are formed. The axial ends can be widened in a funnel shape.

The medical stent is particularly suitable for use in intracranial blood vessels. Such blood vessels have a comparatively small cross-sectional diameter and are often very tortuous. For this purpose, the stent is designed to be highly flexible, so that on the one hand it can be compressed to a very small cross-sectional diameter and on the other hand it has a high degree of bending flexibility, which enables it to be fed into small cerebral blood vessels.

Stenoses are narrowing of blood vessels that lead to a change in the fluid dynamics of the blood flow. This can result in increased blood pressure, which in particular in the area of the stenosis leads to stress on the vessel walls. In the worst case, this can lead to tissue peeling or rupture. The risk of deficiency is an undersupply due to the reduction in size or the closure of the lumen and due to the detachment of particles, which then float away distally and smaller distal vessels shoot. Stenoses are based on changes in the vascular wall caused by inflammatory processes (atherosclerotic changes).

It is known to use stents to regress a stenosis. These can be brought to the treatment site via a balloon catheter. There the stenosis is widened with the help of the balloon on the balloon catheter. The stent expanded in the area of the stenosis then supports the blood vessel. The disadvantage of using known stents, however, is that the lattice structure of the stent is pressed into the narrowed and often already irritated vessel wall due to the forces generated during the expansion and can thus lead to injuries, which in turn can lead to thrombus formation. Small thrombi can swim away distally and lead to blockages. The atherosclerotic tissue itself is also fragile and can break in contact with the lattice structure and float away. On the other hand, the meshes of the stents are so large that thrombi are not securely retained.

In addition, the known stents grow into the tissue only with difficulty and thus form an obstacle to the blood flow in the long term, on which thrombi can form.

Against this background, the object of the invention is to provide a medical system for the treatment of stenoses with a balloon catheter and an implant with which a treatment site in intracranial blood vessels can be easily reached and with which the side effects of stenosis therapy are reduced.

According to the invention, this object is achieved by the subject matter of claim 1.

The invention is based on the idea of specifying a medical system for the treatment of stenoses in intracranial blood vessels with a compressible and self-expanding implant for covering the stenosis, which has a lattice structure which is provided at least in sections with a cover made of electrospun tissue that is irregular has large pores, as well as a balloon catheter for dilating the stenosis and for delivering the implant into the blood vessel. The combination according to the invention of the implant with the electrospun cover and the balloon catheter has particular advantages in the treatment of stenoses in intracranial blood vessels. The self-expanding implant can be arranged in the region of the stenosis, with the self-expanding properties of the implant producing close contact with the vessel wall. The balloon catheter can be used to widen the stenosis before and after inserting the implant. The first expansion takes place with the balloon of the balloon catheter. Micro-injuries occurring in this phase can be shielded from the bloodstream by the cover in the second treatment step.

In particular, the balloon can generate a relatively high expansion pressure which expands the constricted blood vessel. In the implanted state, the self-expandable implant permanently exerts a radial force on the vessel wall and thus ensures that there is no renewed narrowing or stenosis. Due to its fine structure, the electrospun cover ensures on the one hand that the implant bonds well to the vessel wall and, in particular, grows in, since the electrospun cover supports the formation of endothelial cell tissue. The cover initially distributes the force on the vessel a little more homogeneously. In addition, the cover ensures that small thrombi that form on the injured vessel wall do not swim further distally. The fine-pored cover offers a good substrate for cell proliferation and thus for the formation of a new endothelial layer.

On the other hand, the cover is highly flexible and thin, so that the implant can be compressed well and is very flexible. In this way, the implant can be easily inserted into the often tightly wound and small blood vessels in the intracranial area by means of the balloon catheter.

The fine-pored, electrospun cover also has the effect that the radial force of the implant and the expansion force of the balloon are distributed over a relatively large contact area, so that the lattice structure is prevented from "cutting" into the vascular wall tissue (Soft plaque), which often form in the area of stenoses, and vulnerable plaque are often a consequence an arteriosclerotic disease, which is also a major cause of stenosis. Usually, the accumulation of deposits rich in fat (plaque) ultimately leads to a narrowing, i.e. a stenosis, of the blood vessel. Vulnerable plaque can burst and ultimately trigger thrombosis. By means of the fine-pored, electrospun cover, however, vulnerable plaque is stabilized, so that the risk of bursting and thus the risk of thrombosis can be reduced.

It is particularly preferred if the cover ^{comprises at least 10 pores over an area of 100,000 μm 2} , which have a size between 5 μm ² to 15 μm ² and / or at least 15 μm ² . In particular, these pores can have a size of at least 30 μm ² . The at least 10 pores of the cover can each have an incircle diameter of at least 4 pm, in particular at least 5 pm, in particular at least 6 pm, in particular at least 7 pm, in particular at least 8 pm, in particular at least 9 pm, in particular at least 10 pm, in particular at least 12 pm, in particular at least 15 pm, in particular at least 20 pm.

In the course of the production of the cover, the minimum size of the pores can be adjusted in particular through the duration of the electrospinning process. The electrospun fabric cover is thin and flexible over it, which supports the flexibility of the lattice structure. In particular, in contrast to previously known covers made from other textile materials, the cover hardly prevents the lattice structure from being compressed. Overall, the implant can therefore be compressed to a considerably smaller cross-sectional diameter and thus guided into particularly small blood vessels via small balloon catheters.

The high flexibility of the carrier structure or the lattice structure can be achieved in particular if the lattice structure has a closed cell ring which has at most 12 immediately adjacent cells in the circumferential direction of the lattice structure. The closed cell ring also enables the lattice structure to be withdrawn again into a balloon catheter 60 after a partial release, since, because of the closed structure, no lattice elements protrude that could get caught on the catheter tip. In particular, all cell rings of the lattice structure can be closed and a maximum of 12, in particular have a maximum of 10, in particular a maximum of 8, in particular a maximum of 6, cells directly adjacent in the circumferential direction of the lattice structure. It is possible for all cell rings to include at least 3 cells which are directly adjacent to the lattice structure in a circumferential direction.

By delimiting the cells in the circumferential direction on a cell ring, the grid elements and their connectors or crossing points are also limited. Because of the limited number of lattice elements in the circumferential direction, the lattice structure can be compressed to a small cross-sectional diameter in which the lattice elements are preferably in direct contact with one another. In addition, by delimiting the cells in the circumferential direction, increased feedability can also be achieved, so that the lattice structure, in particular also in the compressed state, can be guided through tightly wound vessels by means of the balloon catheter.

The lattice elements preferably delimit closed cells of the lattice structure, each closed cell being delimited by four lattice elements. The closed cell can have a diamond-shaped basic structure. The closed cells achieve a high stability of the lattice structure, which is advantageous for the function of the lattice structure as a carrier for the cover. In particular, high stability is achieved in the axial direction, i.e. in the direction of a longitudinal axis of the lattice structure, which improves the delivery of the implant through the balloon catheter. In the radial direction, the lattice structure can have increased flexibility due to the closed cells, which leads to an improved radial force.

In general, in the context of the present application, all geometrical details with regard to the implant relate to the resting state of the implant. The state of rest is the expanded state of the implant in which the implant does not exert any radial forces.

The balloon catheter can have at least two channels and a balloon, an inflation channel being fluidly connected to the balloon and a delivery channel extending through the balloon. The supply channel can have a proximal insertion opening and a distal exit opening which releases the implant. Of the at least two channels, the inflation channel is for it provided to fill the balloon with a fluid in order to expand the balloon, or to discharge the fluid from the balloon again in order to compress the balloon. The fluid can be a sodium chloride solution, in particular with a contrast medium for visualization under X-rays.

The feed channel is preferably designed as a through channel and enables the implant to be guided to the treatment site. Since the implant is easily compressible because of the thin and flexible cover, the feed channel can be correspondingly small. In addition, the special structure of the electrospun cover means that the implant can be pushed through the feed channel with comparatively low frictional resistance. To this extent, it is provided in a preferred variant of the medical system according to the invention that the implant, in the compressed state, can be moved through the feed channel or is arranged in the feed channel.

In order to further facilitate the feeding of the implant, the feed channel can furthermore have a friction-reducing inner coating for a translational movement of the implant in the feed channel.

The suitability of the medical system for use in intracranial blood vessels is promoted in particular if the feed channel has an inner diameter of at most 991 pm (0.039 inch), in particular at most 686 pm (0.027 inch), in particular at most 635 pm (0.025 inch), in particular at most 533 pm (0.021 inch), in particular at most 432 pm (0.017 inch), in particular at most 406 pm (0.016 inch), in particular at most 381 pm (0.015 inch), in particular at most 330 pm (0.013 inch).

The balloon catheter can have at least one X-ray marker. The balloon catheter 60 preferably comprises three X-ray markers, a first X-ray marker being arranged in the region of the distal exit opening of the feed channel, a second X-ray marker in the region of a distal balloon end and a third X-ray marker being arranged in the region of a proximal balloon end. The X-ray markers enable a surgeon to record the position of the balloon within a blood vessel under X-ray control and to correct it if necessary. In order to ensure that the cover enables good accumulation of endothelial cells on the one hand and a large contact area with the vessel wall on the other hand, it is preferably provided that the pores have a size of at most 750 gm ² , in particular at most 500 gm ² , in particular at most 300 gm ² .

For a good stenosis treatment and for a good covering of the plaques it has also proven to be expedient if at most 20% of the area of the covering is formed by pores which have a size of at least 500 gm ² . Alternatively or additionally, at most 50% of the area of the cover can be formed by pores which have a size of at least 300 gm ² .

The cover can be firmly, in particular materially connected, to the lattice structure. In particular, it can be provided that the cover is applied directly to the lattice structure. For example, the electrospinning process can take place directly on the lattice structure, so that a connection to the lattice structure is established at the same time as the cover is formed. The cover can be materially connected to the lattice structure. For example, the cover can be connected to the lattice structure by an adhesive connection. The adhesive connection can be established by a flaft mediator. The flaft mediator can, for example, comprise or consist of polyurethane.

The fixed connection between the cover and the lattice structure prevents the cover from becoming detached from the lattice structure when the implant is fed through the feed channel of the balloon catheter. At the same time, this facilitates the positioning of the implant under X-ray control, since it is sufficient to attach appropriate implant X-ray markers either to the lattice structure or to the cover. Since the relative position between the cover and the lattice structure is constant, additional implant x-ray markers, which would make a relative displacement between the cover and the lattice structure recognizable, are not required. Overall, the number of implant x-ray markers, for example x-ray marker sleeves, can be reduced, which in turn has a positive effect on the compressibility of the implant.

The lattice structure can be sheathed at least partially and / or in sections by a flaft mediator, in particular polyurethane. In particular, the Adhesion promoters form the integral connection between the cover and the lattice structure. Specifically, the grid elements of the grid structure can be encased by an adhesion promoter, in particular polyurethane. In all cases it can be provided that the adhesion promoter forms the material connection between the cover and the lattice structure. The adhesion promoter preferably surrounds the entire grid element and in this respect forms a casing for the grid element.

In a preferred embodiment of the invention it is provided that the cover is arranged on an outside of the lattice structure. In this constellation, the lattice structure forms a support structure that applies sufficient radial force to fix the cover against a vessel wall. To this extent, the carrier structure supports the cover arranged on the outside. Alternatively, the cover can also be arranged on an inside of the lattice structure.

Alternatively or additionally, the cover can be arranged on an inside of the lattice structure. In particular, it is possible for the lattice structure to be embedded between two covers which are each formed by an electrospun fabric. The lattice elements of the lattice structure can in this respect be completely encased by the electrospun fabric. Specifically, it can be provided that the electrospun fabric of a cover on the inside of the lattice structure extends through the cells of the lattice structure and is connected to the electrospun fabric of a cover on the outside of the lattice structure. The grid elements that delimit the cells are encased on all sides by electrospun fabric.

It is preferably provided that the cover is formed from a plastic material, in particular a polyurethane. Such materials have a high elasticity and can be easily produced in fine threads by an electrospinning process. The plastic material makes it possible on the one hand to produce a particularly thin and fine-pored cover. On the other hand, the plastic material already has a high degree of flexibility, so that the implant can be compressed to a high degree. When using polyurethane to form the cover, it has been found to be particularly advantageous if the Shore hardness of the polyurethane is more than 60D, in particular at least 65D, in particular at least 75D. A particularly preferred range is 65D-75D.

It is preferred if the same material is used for the formation of the adhesion promoter and for the formation of the cover. The layer thickness of the adhesion promoter is preferably between 0.1 gm and 3 gm, in particular between 0.2 gm and 2 gm, in particular between 0.3 gm and 1 gm. The layer thickness of the cover is preferably between 1 gm and 35 gm, in particular between 2 gm and 25 gm, in particular between 3 gm and 15 gm, in particular between 5 gm and 10 gm.

It also contributes to the flexibility of the cover if, as is preferably provided, the cover is formed from threads arranged in an irregular network-like manner, which have a thread thickness between 0.1 gm and 3 gm, in particular between 0.2 gm and 2 gm, in particular between 0.3 gm and 1.5 gm, in particular between 0.7 gm and 1.3 gm.

The cover can have a biocompatible coating. The coating can in particular be anti-inflammatory and / or hyperplasia-inhibiting. It is also possible for the coating to have antithrombogenic and / or endothelialization-promoting properties. The coating can have fibrin and / or heparin. It is preferred if the heparin is covalently bound to fibrin or embedded in fibrin.

The heparin contributes, in particular in addition to the mechanically stabilizing effect of the electrospun cover on vulnerable plaques, to lowering the risk of thrombosis. The anti-inflammatory coating, especially in the preferably covalently bound combination of fibrin and heparin, also contributes to the regression of vulnerable plaques.

A fibrin coating can consist of a fibrin nanostructure (fibrin threads); these fibrin threads form a random web on the surface of the cover and provide an additional surface for an anticoagulant can be tied. The fibrin coating that is formed on the reticulate structure can include an anticoagulant that includes heparin or other possible functional molecules such as fibronectin.

In a preferred embodiment of the invention, the cover of the lattice structure and / or the balloon of the balloon catheter comprises, in particular contains, a pharmaceutically active substance or is coated therewith. In particular, the pharmaceutically active substance can be embedded in the material of the cover. In general, the pharmaceutically active substance can be a substance which is released on the vessel wall of the blood vessel. The substance is released from the balloon and then held in place by the cover in the second step.

The lattice structure can in principle be designed as a one-piece lattice structure. It is also possible that the lattice structure is formed from interwoven wires. To this extent, it is provided in preferred embodiments that the lattice elements form webs which are integrally coupled to one another by web connectors (one-piece lattice structure). Alternatively, the lattice elements can form wires that are braided with one another (braided lattice structure). While a braided lattice structure is characterized by particularly high flexibility, in particular bending flexibility, a one-piece lattice structure has a comparatively thin wall thickness, so that the lattice structure has less of an influence on the blood flow within a blood vessel.

The cover can have an extensibility according to ASTM 412 between 300% and 550%, in particular between 350% and 500%, in particular between 375% and 450%. According to ASTM 412, the elastic modulus of the cover can be> 15 - 21 MPa (psi) at 50% elongation:> 18 <26 MPa (psi) at 300% elongation:> 32 <41 MPa (psi) . According to ASTM D 2240, the Shore hardness of the cover can be between 80A and 85D, in particular between 90A and 80D, in particular between 55D and 75D.

To improve repositionability, the cover can be reset to its original configuration, in particular to its unfolded configuration, after the lattice structure has been compressed and released again.

The threads or monofilaments of the fabric can be materially connected to one another at their crossing points in the fabric and prevent mutual slipping. This ensures the initial pore size / porosity determined by the manufacturing process. The cohesive connection is also provided after compression, delivery through the catheter and renewed release of the implant in the vessel and remains in place even when a side branch flows through the tissue.

In addition to the pores formed by electrospinning, the fabric can be perforated at least in regions by further pores which are formed in the electrospun fabric by processing the fabric, in particular by laser cutting. As a result, a targeted and, if desired, area-wise increase in the porosity or enlargement of the pores is achieved after the electrospinning process. For example, laser-cut, defined pores can be formed over the entire circumference or only on part of it.

The fabric is preferably perforated to at least 25%, in particular to at least 40%, in particular to at least 50% of the circumference of the lattice structure (10) through the further pores. Thus, for example, the area opposite the aneurysm neck can be perforated in a targeted manner.

The fabric can be free of further pores to at least 25%, in particular to at least 40%, in particular to at least 50% of the circumference of the lattice structure. In other words, part of the fabric is not post-treated or subsequently perforated. There are no other pores in this part of the fabric in addition to those formed by electrospinning Pores introduced into the tissue. The tissue in this area consists only of the pores formed by electrospinning. The area of the tissue that is free of further pores can be arranged in the implanted state in the area of the aneurysm neck. This can be desirable, for example, if the porosity of the electrospun tissue is still advantageous for the treatment of the aneurysm.

A combination of areas of unchanged electrospun fabric and subsequently perforated electrospun fabric is possible.

The further pores can be formed in both axial directions starting from the axial center of the lattice structure. In a further exemplary embodiment, additional pores can be arranged on the proximal or distal side within the covering or the fabric.

The length over which the further pores can be distributed corresponds to at least 25% of the axial length of the cover or the fabric, in particular at least 30%, in particular at least 40%, in particular at least 50% of the axial length of the cover or the fabric.

In order to promote the flow, the size of the further pores can be at least 50 pm, in particular at least 100 pm, in particular at least 200 pm, in particular at least 300 pm. The distances between the further pores in relation to the diameter of the further pores can be at least 1 times the distance, in particular at least 1.5 times the distance, in particular at least 2 times the distance, in particular at least 2.5 times the distance. In the case of a 1-fold distance, this corresponds to the diameter of a further pore. In a particularly preferred embodiment, the circumferential contour of the cover is marked at least in sections, in particular over its entire circumference, by an X-ray visible means. This can be achieved, for example, by radiopaque wires that are braided into the lattice structure along the contour of the cover. It is also possible to contour the cover by a series of radiopaque sleeves, for example Pt-Ir sleeves or crimped C-sleeves.

The position of the covering or the fabric is thus visible under X-rays so that the doctor can safely place the device - even in the correct rotational position.

As such, the tissue can have a radiopaque agent. For example, the threads of the fabric can be filled with a radio-opaque material, in particular with at least 10% up to a maximum of 25% radio-opaque material, e.g. barium sulfate BaS04. The basic color of the threads of the fabric can be transparent, if barium sulfate BaS04 is added, these can appear white / yellowish.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the attached illustrations. Show in it:

1: a side view of a stent of a medical system according to the invention according to a preferred embodiment;

Fig. 2: a microscope image of a cover of the

Implant of a medical system according to the invention according to a preferred embodiment;

Fig. 3: a microscope image of a cover of the

Implant of a medical system according to the invention according to a further exemplary embodiment;

4: a perspective illustration of a lattice structure of a stent of a medical system according to the invention according to a further preferred exemplary embodiment;

5: a scanning electron microscope image of a

Covering the implant of an inventive medical system according to a further embodiment at a magnification of 500 times;

6 is a scanning electron microscope photograph of

Cover according to FIG. 5 at a magnification of 3,500 times;

7 shows a longitudinal section through the balloon catheter of a medical system according to the invention according to a preferred embodiment;

8 shows a cross section through the balloon catheter of a medical system according to the invention according to a further preferred embodiment with coaxially arranged channels;

9 shows a cross section through the balloon catheter of a medical system according to the invention according to a further preferred exemplary embodiment with channels arranged next to one another;

10 shows a longitudinal section through the balloon catheter according to FIG. 8; and

11 shows a longitudinal section through the balloon catheter according to FIG. 8, with X-ray markers additionally being provided.

The attached figures show an implant in the form of a stent 1 and the balloon catheter 60 of a medical system for treating stenoses in intracranial blood vessels.

The stent 1 has, in particular, a lattice structure 10 that is compressible and expandable. In other words, the lattice structure 10 can assume a feeding state in which the lattice structure 10 is relatively small Has cross-sectional diameter. The lattice structure 10 is self-expanding, so that the lattice structure 10 automatically expands to a maximum cross-sectional diameter without the influence of external forces. The state in which the lattice structure 10 has the maximum cross-sectional diameter corresponds to the state of rest. In this state, the lattice structure 10 does not exert any radial forces.

The lattice structure 10 is preferably formed in one piece. In particular, the lattice structure 10 can have a cylindrical shape, at least in sections. The lattice structure 10 is preferably produced from a tubular blank by laser cutting. Individual grid elements or webs 11, 12, 13, 14 of the grid structure 10 are exposed by the laser-cutting processing. The regions removed from the blank form cells 30 of the lattice structure 10.

The cells 30 essentially have a diamond-shaped basic shape. In particular, the cells 30 are delimited by four webs 11, 12, 13, 14 each. In the exemplary embodiment shown, the webs 11, 12, 13, 14 have at least partially a curved, in particular S-shaped, course. Other shapes of the webs 11, 12, 13, 14 are possible.

For example, it is possible that the lattice structure comprises circumferential segments of closed cells, the cells being delimited by at least four webs each, which are coupled to one another at connection points and of which two webs are adjacent in the circumferential direction UR of the lattice structure and coupled to one another at a connection point are differently flexible such that the web with higher flexibility is more deformable than the web with lower flexibility during the transition of the lattice structure from the expanded state to the compressed state, and of which the webs with higher flexibility and the webs with lower flexibility are each arranged diagonally opposite one another are such that two connection points of the cell arranged opposite one another in the longitudinal direction LR of the lattice structure are offset in opposite directions in the circumferential direction UR during the transition of the lattice structure from the expanded state to the compressed state. In particular, all cells of a circumferential segment can be designed in the same way are such that the entire lattice structure is twisted at least in sections during the transition from the expanded state to the compressed state.

In a further embodiment, the lattice structure can have webs which are connected to one another in one piece by web connectors and which delimit closed cells of the lattice structure. The web connectors each have a connector axis that extends between two cells that are adjacent in the longitudinal direction of the lattice structure. The web connectors rotate during the transition of the lattice structure from the production state to a compressed state, so that an angle between the connector axis and a longitudinal axis of the lattice structure changes, in particular increases, during the transition of the lattice structure from a fully expanded production state to a partially expanded intermediate state. The lattice structure can be formed in one piece. The webs of the lattice structure can be cut free, for example, by laser-cutting machining of a tubular blank. The cut areas form the cells that are delimited by the bars. This is preferably a lattice structure with a closed cell design. The cells are completely enclosed by bars. In particular, the cells can have an essentially diamond-like basic shape. In other words, the cells are preferably delimited by four webs each.

The web connectors, which form part of the lattice structure in one piece, can consequently each couple four webs to one another. The web connectors essentially form intersection points of the webs.

When the lattice structure is compressed or expanded, the height and width of the individual cells of the lattice structure change. The degree of change in height and width of the cell is influenced by the rotation of the bar connectors. In particular, the rotation of the web connectors results in a different, in particular dynamically changing, ratio between cell height and cell width. This leads to a comparatively high flexibility of the lattice structure, in particular in the transverse axial direction. In particular, the web connector rotation enables the lattice structure to be ovalized when it is passed through narrow hollow body organs. The lattice structure, which can have a circular cylindrical cross-section at least in sections, can thus assume an oval cross-sectional geometry at least locally when passing through a curved vessel.

The cells 30 each have cell tips 31, 32 which define the corner points of the diamond-shaped basic shape. The cell tips 31, 32 are each arranged on web connectors 20 which each connect four webs 11, 12, 13, 14 to one another in one piece. Four webs 11, 12, 13, 14 extend from each web connector 20, each web 11, 12, 13, 14 being assigned to two cells 30. The webs 11, 12, 13, 14 each delimit the cells 30.

Fig. 1 shows the lattice structure 10 in the expanded state or in the rest state. It can be clearly seen that the web connectors 20 are essentially each arranged on a common circumferential line. Overall, several cells 30 thus form a cell ring 34 in the circumferential direction of the lattice structure 10. Several cell rings 34 connected to one another in the longitudinal direction form the entire lattice structure 10. In the exemplary embodiment shown, the cell rings 34 each include six cells 30. In this context, it is pointed out that the Lattice structure 10 is preferably formed from interconnected cell rings that have the same cross-sectional diameter.

When the lattice structure 10 is released from the balloon catheter 60, the lattice structure 10 automatically expands radially. The lattice structure 10 undergoes several degrees of expansion until the lattice structure 10 reaches the implanted state. In the implanted state, the lattice structure 10 preferably has a cross-sectional diameter that is approximately 10% to 30%, in particular approximately 20%, smaller than the cross-sectional diameter of the lattice structure 10 in the rest state. Thus, in the implanted state, the lattice structure 10 preferably exerts a radial force on the surrounding vessel walls. The implanted state is also referred to as the "intended use configuration".

As can be clearly seen in FIG. 1, implant x-ray markers 50 are provided in the case of the stent 1. The implant x-ray markers 50 are arranged on cell tips 31, 32 of the cells 30 of the lattice structure 10 on the edge. Specifically, the implant x-ray markers 50 can be formed as x-ray-visible sleeves, for example made of platinum or gold, which are placed on the cell tips 31, 32 of the edge-side Cells 30 are crimped. It can be seen in FIG. 1 that three implant x-ray markers 50 are arranged at each longitudinal end of the lattice structure 10.

The lattice structure 10 according to FIG. 1 can be divided into three sections. Two edge-side sections, which are each formed by two cell rings 34, are connected by a central section which comprises five cell rings 34. The cells 30 of the central section essentially have a diamond-shaped geometry, with all of the webs 11, 12, 13, 14 of the cells 30 of the central section having essentially the same length. The edge-side cell rings 34 each include cells 30, in which two in the circumferential direction immediately adjacent webs 11, 12, 13, 14 are each longer than the axially adjacent webs 11, 12, 13, 14 of the same cell 30. In this respect, the edge-side Cells 30 essentially have a kite-like basic shape.

The medical device according to FIG. 1 further comprises a cover 40 which is arranged on an outside of the lattice structure 10. The cover 40 spans the entire lattice structure 10 and in particular covers the cells 30. The cover 40 is formed from an electrospun fabric and is therefore characterized by a particularly thin wall thickness. At the same time, the cover 40 is sufficiently stable to follow an expansion of the lattice structure 10. The cover 40 is preferably completely and firmly connected to the lattice structure 10. Specifically, the cover 40 is preferably glued to the webs 11, 12, 13, 14, for example by means of an adhesion promoter.

The cover 40 can extend over the entire lattice structure 10, as is shown in FIG. 1. It is alternatively possible that the cover 40 spans only part of the lattice structure 10. For example, cells 30 on the edge can be uncovered at one axial end or at both axial ends of the lattice structure 10. In this respect, the cover 40 can end before the last or penultimate cell ring 34 of the lattice structure 10. The cover-free cell rings 34 enable good coupling to a transport wire. The area of the stent that has the cover 40 can be identified by further implant x-ray markers. It is also possible for radiopaque material to be embedded in the cover. The design of the cover 40 can be clearly seen in the microscope recordings according to FIGS. 2 and 3. It can be seen that the cover 40 has a plurality of irregularly sized pores 41 which are each delimited by threads 42. The electrospinning process forms a plurality of threads 42 which are irregularly aligned with one another. The pores 41 are formed in the process. It can also be seen in FIG. 2 that the pores 41 have a comparatively small pore size, although some pores 41 are sufficiently large to ensure blood permeability. Specifically, four pores 41 are graphically highlighted in FIG. 2, which have a size of more than 30 μm ² . The density of the pores 41 with a size of more than 30 μm ² shows that the cover has at least 10 such pores 41 ^{over an area of 100,000 μm 2.}

FIG. 3 shows a further exemplary embodiment of a cover 40 in which an overall larger pore size has been set. It can be seen that some pores 41 have a ^{size of more than 30 μm 2} , although a pore size of 300 μm ^{2 is} not exceeded.

In FIGS. 2 and 3 it can be seen in each case that the threads 42 of the cover 40 cross multiple times. A special feature of the electrospinning process, however, is that in the cover 40 there are points at which only, i.e. not more than, two threads 42 cross one another. It can be seen from this that the cover 40 overall has a very thin wall thickness and is therefore highly flexible.

The high flexibility of the cover 40 in combination with the high flexibility of the lattice structure 10 means that a stent 1 can be provided which can be introduced into a blood vessel through a very small balloon catheter 60. In particular, the balloon catheter 60 can have a size of 6 French, in particular at most 5 French, in particular at most 4 French, in particular at most 3 French, in particular at most 2 French. Specifically, stents 1 according to the exemplary embodiments described here can be combined with balloon catheters 60 which have an inner diameter of at most 991 pm (0.039 inch), in particular at most 686 pm (0.027 inch), in particular at most 635 pm (0.025 inch), in particular at most 533 pm ( 0.021 inch), especially at most 432 µm (0.017 inch), especially at most 406 mih (0.016 inch), in particular at most 381 mih (0.015 inch), in particular at most 330 mih (0.013 inch).

In particularly preferred variants, the layer thickness of the cover 40 is at most 6 mih, in particular at most 4 mih, in particular at most 2 mih. At most 4, in particular at most 3, in particular at most 2, threads 42 intersect. Generally, intersection points are provided within the electrospun structure of the cover 40, in which only 2 threads 42 intersect.

The lattice structure 10 preferably has a cross-sectional diameter at rest between 2.0 mm and 10 mm, in particular between 2.5 mm and 7 mm, in particular between 2.5 mm and 6 mm, in particular between 4.5 mm and 6 mm, in particular between 3.0 mm and 5 mm, in particular about 3.5 mm or about 4.5 mm. In general, it is preferred if the lattice structure 10 for the treatment of vulnerable plaque or soft plaque in intracranial blood vessels, for example the internal carotid artery or intracranial vessels distal therefrom, has a cross-sectional diameter of at most 6 mm, in particular between 2.5 mm and 5.5 mm. For the treatment of vulnerable plaque or soft plaque, preferably also for the treatment of stenoses, in extracranial blood vessels, in particular in extracranial sections of the fial artery, for example the external carotid artery (external carotid artery), the lattice structure 10 can have a cross-sectional diameter of at most 10 mm, in particular between at least 6 mm and at most 10 mm.

4 shows a braided lattice structure 10 which, in a preferred exemplary embodiment, can form a carrier for a cover 40. The braided lattice structure 10 is formed from a single wire 16 which is braided in a tubular shape. The wire ends are connected to a connecting element 18 within the lattice structure 10.

The wire 16 has several sections, which are referred to as grid elements 11, 12, 13, 14. Each section of the wire 16 that runs between two crossing points 19 is used as an independent grid element 11, 12, 13, 14 designated. It can be seen that four grid elements 11, 12, 13, 14 each delimit a mesh or cell 30.

The braided lattice structure 10 has widening axial ends, which are referred to as flaring 17. The wire 16 is deflected in each flaring 17 and forms end loops 15. In the exemplary embodiment shown, a total of six end loops 15 are provided on each flaring 17. Every second end loop 15 carries an implant X-ray marker 50 in the form of a crimp sleeve. Thus, there are three implant x-ray markers 50 at each axial end of the lattice structure 10.

In FIGS. 5 and 6, an exemplary embodiment of the stent 1 is shown in different magnifications of a scanning electron microscope image. The stent comprises a lattice structure 10 according to FIG. 4, which is formed with a cover 40 made of an electrospun fabric. The cover 40 is arranged on an outside of the tubular lattice structure 10.

FIG. 5 shows a 500-fold enlargement of a region of the device which comprises a cell tip 32 of the lattice structure 10. Two grid elements or webs 11, 13 of a cell 30 meet in the cell tip 32. The cover 40 covers the webs 11, 12. It can be seen that the cover 40 has a large number of pores 41 of different sizes, i.e. completely free through openings.

The 3,500-fold enlargement according to FIG. 6 shows a section of the cover 40 according to FIG. 5 in detail. The course of the individual threads 42 of the electrospun fabric can be clearly seen. The threads 42 delimit pores 41, the pores 41 being irregular. In any case, it can be seen that some pores 41 have a larger passage area than other pores 41. The larger pores 41 allow nutrients to pass through the cover 40.

7 shows a balloon catheter 60 for feeding the stent 1 into a blood vessel. The balloon catheter 60 comprises two channels 61, 62. It is also possible to have more than two channels 61, 62, for example three, four or more than four channels 61, 62 to be provided.

The balloon catheter 60 further comprises a balloon 63 which is arranged in the distal region of the channels 61, 62. As illustrated in FIG. 7, as well as in FIGS. 10 and 11, the balloon 63 is provided in the region of the catheter tip. The balloon 63 is spaced apart from the outlet opening 64 of the feed channel 62, so that a balloon-free section of the feed channel 62 is formed between the outlet opening 64 and the distal balloon end 69. The balloon 63, in particular a proximal end 68 of the balloon 63, is fluidly connected to an inflation channel 61, as can be seen in FIGS. 10 and 11. The balloon 63 and the inflation channel 61 are arranged in alignment in the extended state of the balloon catheter 60. To connect the inflation channel 61 to the balloon 63, the wall of the inflation channel 61 is elongated and merges into the balloon wall. The transition between the inflation channel 61 and the balloon 63 takes place through a continuous increase in diameter between the inflation channel 61 and the maximum outer circumference of the balloon 63 in the expanded state (see FIGS. 10, 11).

The inflation channel 61 and the balloon 63 are formed in one piece. It is also possible to design the balloon 63 and the inflation channel 61 in two parts and to provide an additional connecting piece between the balloon 63 and the inflation channel 61.

The connection according to FIGS. 10 and 11 is particularly suitable for the coaxial arrangement of the two channels 61, 62 according to FIG. The annular gap 72 formed between the two channels 61, 62 merges into the inner volume of the balloon 63. The connection between the inflation channel 61 and the balloon 63 can be configured differently, for example if the two channels 61, 62 are arranged next to one another, as shown in FIG. 9. In this case, the connection between the balloon 63 and the inflation channel 61 is arranged to the side of the supply channel 62 (not shown).

The inflation channel 61 is used to supply the balloon 63 with a fluid or to discharge the fluid from the balloon 63. The fluid can be, for example, a saline solution or sterile water. The fluid can also be gaseous, for example ambient air. In practice, the fluid is often an air / liquid mixture.

The balloon catheter 60 comprises a supply channel 62 with an exit opening 64. The exit opening 64 is arranged distally and connects the supply channel

62 with the environment, in particular with the blood vessel in which the stent 1 is released. The outlet opening 64 and the inner diameter of the feed channel 62 are adapted in such a way that the feed channel 62 exercises a retaining function for the stent 1 arranged in the feed channel 62. This means, for example, that the wall of the feed channel 62 is so strong that it can absorb the radial forces exerted by the self-expandable stent 1. Furthermore, the feed channel 62 is sufficiently flexible that the catheter tip can adapt to relatively narrow vessel curvatures.

As can be seen in FIGS. 7, 10 and 11, the feed channel 62 extends through the balloon 63. This means that the balloon 63 is arranged around the outer circumference 71 of the feed channel 62. The feed channel 62 and the balloon 63 are arranged coaxially.

The assignment of the balloon 63 to the supply channel 62, which is adapted for the supply of the stent 1, has the advantage that the balloon catheter 60 fulfills a double function. On the one hand, the balloon catheter 60 is used to feed the stent 1 through the feed channel 62. On the other hand, the balloon 63 arranged in the region of the catheter tip can be used to perform the required dilation or widening of the vessel without having to change the catheter. To implement this principle, it may be sufficient that the feed channel 62 is generally assigned to the balloon 63, specifically in the region of the catheter tip, so that the balloon catheter 60 can be used both for releasing the stent 1 and for dilating, in particular for pre-dilating the stenosis and / or can be used to expand the implanted stent 1. The symmetrical arrangement of the supply channel 62 and the balloon 63, as shown in FIGS. 7, 10 and 11, has the advantage that a simple radial expansion of both the vessel and the implanted stent 1 is possible, the supply channel 62 from balloon

63 is protected or does not come into contact with the vessel or with the implanted stent 1 when the balloon 63 is expanded. The double function of the balloon catheter 60 is achieved in that the supply channel 62 is connected to a proximally arranged, extracorporeal connection in use, which is adapted for introducing the stent 1 into the supply channel 62. In practice, this means that the extracorporeal connection is arranged at the proximal end of the catheter line 70, that is, at a distance from the catheter tip. The extracorporeal connection for the feed channel 62 is thus directly accessible to the user. The connection can be adapted, for example, for loading the stent 1, the stent 1 being moved through the feed channel 62 from the extracorporeal connection to the catheter tip. Alternatively, the extracorporeal connection can be used in connection with a preloaded stent located in the region of the catheter tip, an actuating element being movable through the extracorporeal connection and the feed channel 62, for example a pusher or a guide wire with a slightly larger diameter than the Stent 1, which is advanced up to the preloaded stent 1 and cooperates with this to release. The extracorporeal connection for the supply channel 62 can comprise a loading lock for stents 1, which is known per se. The connection can for example comprise a Luer connector.

As shown in FIG. 8, in one exemplary embodiment the feed channel 62 is arranged coaxially in the inflation channel 61. An annular gap 72 is formed between the two channels 61, 62, which acts as a control lumen for the balloon 63. The supply channel 62, which is arranged in the interior of the inflation channel 61, forms the main lumen through which the stent 1 is moved.

An alternative arrangement of the two channels 61, 62 is shown in FIG. 9, the working channel 61 and the supply channel 62 being arranged next to one another, in particular parallel to one another. A catheter line 70, which fixes the arrangement of the two channels 61, 62, is arranged around the two channels 61, 62. In general, it is preferred that the diameter of the feed channel 62 is greater than the diameter of the inflation channel 61.

In FIGS. 10 and 11 it is shown that the distal balloon end 69 is connected to the outer circumference 71 of the feed channel 62 in a fluid-tight manner. The proximal end of the balloon 68 is fluidly connected to the inflation channel 61. That closes the On the one hand, the balloon 63 is fluid-tight with the supply channel 62 and, on the other hand, can be inflated or deflated through the inflation channel 61.

The inflation channel 61 is connected to a proximally arranged connection which is extracorporeal in use. In connection with the extracorporeal connection for the feed channel 62, a multiple connection, for example a Y-Luer connector, is possible. The connector or connection for the inflation channel 61 is either permanently or detachably connected or connectable to a pressure device. The pressure device is designed to generate an overpressure for inflating or to generate a negative pressure to deflate the balloon 63. The pressure device can comprise a syringe, for example. Other pressure devices are possible.

The feed channel 62 is provided with a friction-reducing inner surface for a translational movement of the stent 1 in the feed channel 62. As a material for the inner surface, for example, PTFE, FEP or FIDPE or similar friction-reducing surface modifications come into question. Other materials for the coating are also possible.

In FIG. 11 it is shown that the catheter tip has several X-ray markers 65, 66, 67. A first X-ray marker 65 is arranged in the area of the distal outlet opening 64 and serves to localize the end of the catheter tip. A second X-ray marker 66 is arranged in the region of the distal balloon end 69. A third X-ray marker 67 is arranged in the region of the proximal balloon end 68. The second and third X-ray markers 66, 67 are used to determine the position of the balloon 63.

The catheter tip can be designed to be atraumatic and / or flexible. Suitable materials for the balloon catheter 60 are plastics, metals, shape memory materials such as nitinol, and X-ray visible materials.

The balloon catheter 60 also enables aspiration through the supply channel 62 during or after the expansion of the stenosis. For this purpose, the feed channel 62 is connected or can be connected to a suction device. This has the advantage that Vascular wall particles detached during expansion can be sucked off through the supply channel 62.

It is also possible to inject a contrast medium through the supply channel 62. Specifically, after the stenosis has been dilated, the supply channel 62 of the balloon catheter 60 can be used for the administration of contrast medium in order to check whether the stenosis has been opened. For this purpose, the feed channel 62 can be or is connected to a corresponding device for injecting a contrast agent, for example a syringe.

The balloon catheter 60 also has the advantage that several stenoses can be expanded and / or several stents 1 can be released by a single balloon catheter 60. Another advantage of the balloon catheter 60 is that the supply channel 62 does not collapse when the balloon 63 is expanded, since it has its own stable channel wall.

The combination of the balloon catheter 60 described here with the stent 1 described here, which has an electrospun cover 40, has proven to be particularly advantageous for the treatment of stenoses. On the one hand, the balloon catheter enables good pre-dilatation of the stenosis. On the other hand, good post-dilatation can also be achieved. The stent 1 provides good support for the widened blood vessel and in particular stabilizes vulnerable plaque due to its particularly flexible and tight cover 40. In addition, the stent 1 with its cover 40 enables good endothelial cell formation, which further stabilizes the widened blood vessel.

List of reference symbols

1 stent

10 lattice structure

11, 12, 13, 70 bar or grid element

15 end loop

16 wire

17 flaring

18 connecting element 19 crossing point 20 bridge connectors

30 cell

31, 32 cell tip 34 cell ring 40 cover

41 pore

42 thread 50 implant x-ray marker 60 balloon catheter 61 inflation channel 62 supply channel

63 balloon

64 distal exit opening

65 first X-ray marker 66 second X-ray marker

67 third X-ray marker

68 proximal end of the balloon

69 distal balloon end

70 catheter line 71 outer circumference

72 annular gap

Claims

EXPECTATIONS

1. Medical system for the treatment of stenoses in intracranial blood vessels using

- A compressible and self-expandable implant (1) for covering the stenosis, which has a lattice structure (10) which is provided at least in sections with a cover (40) made of an electrospun fabric which has irregularly large pores (41) and with

- A balloon catheter (60) for dilating the stenosis and for feeding the implant (1) into the blood vessel.

2. Medical system according to claim 1, dad u rch geken nzeich net that the cover (40) on an area of 100,000 pm ² comprises at least 10 pores (41) which have a size between 5 pm ² to 15 pm ² and / or of at least 15 pm ² .

3. Medical system according to claim 1 or 2, dad u rch geken nzeich net that the balloon catheter (60) has at least two channels (61, 62) and a balloon (64), wherein an inflation channel (61) with the balloon (63 ) is fluidly connected and a supply channel (62) extends through the balloon (63), and wherein the supply channel (62) has a proximal insertion opening and a distal exit opening (64) for the release of the implant (1).

4. Medical system according to claim 2, dad u rch geken nzeich net that the implant (1) in the compressed state is movable through the feed channel (62) or is arranged in the feed channel (62).

5. Medical system according to one of claims 2 to 4, dad u rch geken nzeich net that the balloon catheter (60) has at least three X-ray markers (65, 66, 67) a first X-ray marker (65) in the area of the distal outlet opening (64) of the feed channel (62), a second X-ray marker (66) in the area of a distal balloon end (68) and a third X-ray marker (67) in the area of a proximal balloon end ( 69) is arranged.

6. Medical system according to one of claims 3 to 5, dad u rch geken nzeich net that the feed channel (62) has a friction-reducing inner surface for a translational movement of the implant (1) in the feed channel (62).

7. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the at least 10 pores (41) of the cover (40) each have an inscribed diameter of at least 4 pm, in particular at least 5 pm, in particular at least 6 pm, in particular at least 7 pm, in particular at least 8 pm, in particular at least 9 pm, in particular at least 10 pm, in particular at least 12 pm, in particular at least 15 pm, in particular at least 20 pm.

8. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the cover (40) comprises at least 15 pores (41) ^{on an area of 100,000 pm 2} ^{, the size of at least 30 pm 2} , in particular at least 50 pm ² , in particular at least 70 pm ² , in particular at least 90 pm ² .

9. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the pores (41) have a size of at most 750 pm ² , in particular at most 500 pm ² , in particular at most 300 pm ² .

10. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the cover (40) fixed to the lattice structure (10), in particular cohesively, is connected.

11. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the lattice structure (10) is at least partially and / or in sections encased by an adhesion promoter, in particular polyurethane, in particular wherein the adhesion promoter is the material connection of the cover ( 40) forms with the lattice structure (10).

12. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the cover (40) is formed from a plastic material, in particular a polyurethane.

13. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the cover (40) is formed from threads (42) arranged in an irregular network-like manner, which have a thread thickness between 0.1 μm and 3 μm, in particular between 0, 2 pm and 2 pm, in particular between 0.3 pm and 1.5 pm, in particular between 0.7 pm and 1.3 pm.

14. Medical system according to one of the preceding claims, dad u rch geken nzeich net that the cover (40) has a biocompatible, in particular anti-inflammatory and / or hyperplasia-inhibiting coating (45).

15. Medical system according to claim 14, dad u rch geken nzeich net that the coating comprises fibrin and / or heparin.

16. Medical system according to claim 15, dad u rch geken nzeich net that the heparin is covalently bound to fibrin or embedded in fibrin.