DE102020115600A1 - Implant for the treatment of aneurysms - Google Patents

Abstract

The invention relates to an implant (1) for influencing the blood flow in the area of aneurysms located at vascular branches, the implant (1) being in an expanded state, in which it is implanted in the blood vessel, and in a contracted state, in which it can be moved through the blood vessel, the implant (1) has a first braided structure (2) which is tubular in the expanded state and whose wall is made up of individual interwoven wires (5), the first braided structure (2) adjoining a branch point (7) located at one end of the branch into a second and a third mesh structure (3, 4), wherein the second and the third mesh structure (3, 4) are tubular in the expanded state and their walls consist of individual wires (5 ) are constructed and wherein a part of the wires (5) that form the first braided structure (2) at the branching point (7) in the second mesh structure (3) merges, and a further part of the wires (5), which form the first mesh structure (2), merges into the third mesh structure (4) at the branch point (7). With the help of the implant (1), it is possible to direct the blood flow in such a way that the aneurysm is practically cut off from the blood flow, but the blood flow in the blood vessels themselves is affected as little as possible.

Description

The invention relates to an implant for influencing the blood flow in the area of aneurysms which are located at branching vessels. Such aneurysms are also referred to as bifurcation aneurysms.

Aneurysms are mostly sack-like or spindle-shaped (fusiform) extensions of the vascular wall, which arise primarily at structurally weakened areas of the vascular wall due to the constant pressure of the blood. The inner walls of the aneurysm are correspondingly sensitive and prone to injury. The rupture of an aneurysm usually leads to considerable health impairments, in the case of cerebral aneurysms to neurological failures up to and including death of the patient.

In addition to surgical interventions in which the aneurysm is clamped off by means of a clip, for example, endovascular methods for treating aneurysms are known in particular, two approaches being pursued primarily. On the one hand, the aneurysm can be filled with occlusion means, in particular so-called coils (platinum spirals). The coils promote thrombus formation and thus ensure closure of the aneurysm. On the other hand, it is known to close the access to the aneurysm, for example the neck of a berry aneurysm, from the blood vessel side by means of stent-like implants and to decouple it from the blood flow. Both methods serve to reduce the blood flow into the aneurysm and thus the pressure on the aneurysm, ideally to eliminate it and thus to reduce the risk of the aneurysm rupturing.

When filling an aneurysm with coils, it can happen that the filling of the aneurysm is insufficient, which allows the blood supply to the aneurysm and thus a continued pressure on its inner wall. The risk of constant expansion of the aneurysm and its eventual rupture persists, albeit in a weakened form. In addition, the treatment method is primarily suitable for aneurysms with a relatively narrow neck - so-called berry aneurysms - because otherwise there is a risk that the coils protrude from a wide aneurysm neck into the blood vessel and thrombogenize there, which can lead to occlusions in the vessel. In the worst case, a coil will be completely washed out of the aneurysm and occlude vessels elsewhere. In order to keep the coils in place in the aneurysm sack, the aneurysm neck is often additionally covered with a special stent.

Another intravascular treatment approach relies on so-called flow diverters. These implants are similar in appearance to stents that are used to treat stenoses. Since the task of the flow diverters is not to keep a vessel open, but to close the aneurysm access on the blood vessel side, the mesh size is very narrow; alternatively, these implants are covered with a membrane. A disadvantage of these implants is the risk that branching branches in the immediate vicinity of the aneurysm to be treated are sometimes also covered and thus closed in the medium or long term.

Vascular branching, particularly vascular bifurcations, is a relatively common phenomenon. The blood hitting the front wall through an artery in the area of a bifurcation quickly leads - in the case of a weakening of the vessel wall - to a bulge, which then quickly expands. Such bifurcation aneurysms often have a wide neck, which makes therapy difficult with only occlusion coils.

Vascular implants, which are suitable for creating a “grating” of the aneurysm entrance in the area of a vascular branch, are for example in the international patent applications WO 2012/113554 A1 or WO 2014/029835 A1 disclosed. The aneurysm can then be shut down with occlusion spirals inserted after the implant has been placed. It is also possible for the implant itself to sufficiently decouple the aneurysm from the blood flow. For this purpose, for example, the implant can have a membrane that is placed in the area of the aneurysm neck or in front of the aneurysm neck. If necessary, the blood flow to the aneurysm can also be reduced with filaments, typically small-diameter wires, to such an extent that the additional introduction of occlusion spirals or other occlusion means into the aneurysm can be dispensed with.

From the US 2004/0220653 A1 Y-shaped stents are known. However, these are intended for use in the coronary area to prevent restenoses and are not specifically adapted to the requirements for the treatment of bifurcation aneurysms. The requirements differ; While a conventional stent is supposed to keep the blood vessel (s) open, a flow diverter is about directing the blood flow. Correspondingly, different areas of the Y-shaped stent are also of importance, while in the treatment of stenoses or the prevention of restenoses the arms of the stent are crucial, the branching area is less important. When treating Bifurcation aneurysms behave the other way around. Since the aneurysm typically arises exactly where the blood vessels branch, the area adjacent to the aneurysm is of critical importance because blood flow into the aneurysm is to be blocked.

The object is therefore to provide an implant which is particularly suitable for the treatment of bifurcation aneurysms.

This object is achieved according to the invention by an implant for influencing the blood flow in the area of aneurysms that are localized at branching vessels, the implant being in an expanded state in which it is implanted in the blood vessel and in a contracted state in which it is present the blood vessel is movable, the implant has a first braid structure which is tubular in the expanded state and the wall of which is made up of individual interwoven wires, the first braid structure branching into a second and a third braid structure at a branching point located at one branch end, wherein the second and the third braid structure are tubular in the expanded state and their walls are constructed from individual interwoven wires, some of the wires that form the first braid structure merging into the second braid structure at the branching point t, and a further part of the wires that form the first braid structure merges into the third braid structure at the branching point.

In contrast to the Y-stent known from the prior art, the implant according to the invention has a braided structure, i. H. the implant consists of wires that are intertwined by being passed over and under each other. Such a structure is particularly suitable for expanding in the blood vessel after it has been released and adapting to the vessel walls. The implant has three interconnected tubular braid structures, the second and the third braid structure starting from the first braid structure. Overall, this results in a Y structure. Correspondingly, the first braid structure is typically anchored as a proximal braid structure in the parent blood vessel, while the second and the third braid structure are placed as distal braid structures in the two branching blood vessels. However, other types of placement are also conceivable and may be advantageous under certain circumstances. The fact that the wires which form the first braid structure are at least partially converted into the second or third braid structure is important for the invention. In other words, some of the wires that form the first braid structure merge at the branch point into the second, and some into the third braid structure. The implant is preferably constructed in such a way that all of the wires that are present at the end of the first braid structure where it meets the other two braid structures (branching end) are transferred into the second and third braid structure, one into the second and the other into the third braid structure. It has been found that in this way a particularly good adaptation of the implant to the blood vessels takes place and, in addition, a sufficiently high surface coverage in the area of the aneurysm neck is achieved, which serves to prevent the blood flow into the aneurysm and thus to obliterate and eliminate the aneurysm.

The implant according to the invention is suitable for largely or completely decoupling the bifurcation aneurysm, which is located at the branching point between the first and second and third braid structure, from the blood flow, since at least some of the wires come to lie in front of the aneurysm neck. The blood flow through the main blood vessel, in which there is a plexus structure, and the branching blood vessels, in which the other two plexus structures are, is practically not influenced. As a result, the aneurysm becomes obliterated by the formation of a thrombus due to the lack of blood movement in the aneurysm, which closes the aneurysm.

A tubular braid structure is understood to mean a structure in which the wires form the wall of the tube. It is therefore a round braid. The braid structures preferably have a circular cross section when viewed from the proximal or distal end. In principle, however, deviations from the circular shape are also possible, for example an oval cross-section.

In particular, the implant can be designed so that the first half of the wires that form the first braid structure and are present at the branching end of the first braid structure merge into the second and the second half of the wires into the third braid structure at the branching point. Correspondingly, exactly half of the wires are transferred into the second, the other half into the third braid structure. The structure of the second and third braid structure is therefore basically identical.

The first tubular braid structure is thus made up of a greater number of wires than the other two tubular braid structures. In particular, the number of wires can be exactly twice as high. The radial force exerted by the first braid structure is correspondingly higher. When the first braided structure is placed in the blood vessel, a good one becomes there Anchoring guaranteed. At the same time, the blood flow in the main blood vessel is only insignificantly hindered by the first braid structure, which is closely attached to the vessel wall. On the other hand, the two branching blood vessels are often those with a smaller diameter, so that fewer wires are required here to achieve sufficient surface coverage, which is ensured by dividing the wires between the second and third braid structure. At the same time, the reduction in the number of wires from the first to the second and third braid structure ensures that the radial forces acting on the branching blood vessels do not become too high and the sensitive and often previously damaged vessel walls are not further impaired, although the aneurysm is successfully relieved of blood flow is cut off.

Alternatively, however, a placement is also possible in such a way that another area of the branching point of the Y-shaped implant is placed in front of the aneurysm neck. In this case, the second (or third) braid structure runs through the parent blood vessel, while the first braid structure is introduced into one of the two branching blood vessels. Finally, the third arm of the Y-shaped implant, namely the third (or second) braid structure, is located in the other branching blood vessel. Such a placement can have advantages insofar as the coverage rate immediately in front of the aneurysm neck may be greater because there is a higher mesh density in such an area of the branching point. In this context, the areas of the branching point are understood to be the areas between the braid structures, i. H. the area between the first and second braid structure, the area between the first and third braid structure and the area between the second and third braid structure. Due to the manufacturing process, the mesh density in the areas between the first and second or first and third mesh structure is generally higher than between the second and third mesh structure, since this is where the wires are divided into the second and third mesh structure.

In the case of braided implants, there are crossing points at the points where wires are passed over or under one another. Of two wires in each case which form a crossing point at the branching end of the first braid structure, one wire is preferably transferred into the second and the other wire into the third braid structure. This ensures the close connection of the first with the other two braid structures and also automatically ensures a high braid density especially in the area of the branching point, with one of the branching points being placed in front of the aneurysm.

In principle, other divisions of the wires are also conceivable. For example, the wires can also be divided into the second and third braid structure at each point of intersection; H. the wires that form a first intersection point merge into the second braid structure, the wires that form a second intersection point adjacent to the first intersection point merge into the third braid structure. In this way, too, an even distribution of the wires between the second and third braid structure is achieved.

The braid can in principle be braided in any known manner. It is single and / or multi-braid. A tight braid leads to a high level of stress on the individual wires, especially in the case of a dense braid. In this respect, the multi-braid design is suitable for taking tension out of the braiding, but too much braiding leads to a poor bond in the braiding. The braidness indicates how many wires that cross each other with the wire a certain wire is fed past on the same side before it changes sides in order to then be fed past a corresponding number of crossing wires on the other side. In a two-braid design, for. B. a wire is passed one after the other over two wires crossing the wire, then one after the other below two crossing wires. In the single-braid structure, the wires lie alternately one above the other and one below the other.

The wires can in particular also be plied several times. The division indicates the number of combined, parallel single wires. A single or multiple multiplication is possible, with one or more individual wires running in parallel. Since the wires are usually fed from spools during the manufacture of the braid, this means that one or more individual wires are fed from the corresponding spool to the mandrel on which the braid is produced at the same time. Each wire can consist of a single wire or a strand of several combined and preferably twisted individual wires.

A ply of two or even higher piles results in a higher surface density of the braid, while at the same time reducing the length expansion during the compression of the braid. However, this higher surface density is at the expense of flexibility, also due to increased friction and tension. This can be counteracted by increasing the braidness, i. H. a double or higher braid structure brings an increase in flexibility with it.

Different forms of filaments can be used as wires. These can have a round, oval or also angular cross-section, in particular a rectangular, square or trapezoidal cross-section, with the edges being able to be rounded in the case of an angular cross-section. It is also possible to use flat wires in the form of thin strips. The individual wires can also be composed of several individual filaments that are twisted with one another or also run in parallel. The wires can be solid or hollow on the inside. In addition, the wires can be electropolished to make them smoother and more rounded and thus less traumatic. This also reduces the risk of germs or other contaminants adhering.

The wires are preferably made of metal, but in principle the use of wires made of other materials, for example plastics or polymer materials, is also conceivable. According to the invention, such filaments are also understood to be wires.

In order to ensure that the implant automatically expands after being released in the blood vessel, for example from or out of a catheter, and adapts to the inner walls of the blood vessels, it is preferred to manufacture the wires at least partially from a material with shape memory properties. Nickel-titanium alloys, for example nitinol, or also ternary nickel-titanium-chromium alloys or nickel-titanium-copper alloys are particularly preferred in this context. However, other shape memory materials, for example other alloys or also shape memory polymers, are also conceivable. Materials with shape memory properties make it possible to impress a secondary structure on an implant, which it automatically tries to adopt as soon as it is no longer hindered from expansion.

Also possible is the use of so-called. DFT ^® (Drawn Filled Tubing) wires, that is wires, in which the core of the wire made of a different material than the jacket surrounding the core. In particular, it is advisable to use wires with a core made of a X-ray visible material and a sheath made of a material with shape memory properties. The X-ray visible material can be, for example, platinum, a platinum-iridium alloy or tantalum; the material with shape memory properties, as already mentioned, is preferably a nickel-titanium alloy. Such DFT ^® from wires, for example, offered by Fort Wayne Metals.

Corresponding wires combine the advantageous properties of two materials. The shell with shape memory properties ensures that the implant can expand and adapt to the vessel walls, the X-ray visible material ensures that the implant is visible in the X-ray image and can thus be observed by the attending physician and can be positioned accordingly.

The distal and proximal ends of the wires are preferably designed in such a way that damage to the vessel walls is excluded. For example, wires can be rounded at their ends and thus atraumatic. Corresponding reshaping can be carried out by remelting with the aid of a laser. It is also possible to bring one or more wires together at the respective ends and to create a closure that is as atraumatic as possible. In particular, it is useful to avoid pointed wire ends.

The total number of wires that form the proximal braid structure is preferably 24 to 96. In this way, a dense braid structure is created that fits well against the inner wall of the blood vessels. In addition, the large number of wires ensures good surface coverage and mesh density in the area of the aneurysm. Finally, the relatively large number of wires ensures that even when the wires are divided between the second and third braid structure, each of these braid structures has a sufficient number of wires to ensure that these braid structures can also fulfill their function.

In order to further increase the surface coverage in the area of the aneurysm neck, the implant can be subjected to a shaping process during manufacture in order to increase the number of wires at the branch point in the distal direction. The branch point pointing in the distal direction typically corresponds to the aneurysm neck, i. H. increasing the number of wires in this position provides greater coverage of the neck of the aneurysm and thus an improved cut off from the blood supply. The corresponding shaping processes can be of a mechanical nature, but in particular it is also at least a heat treatment which ensures that the implant in the expanded state has a large number of wires in the distal direction at the branching point. A corresponding heat treatment is particularly useful in the case of wires made from a shape memory material because the heat treatment can be used to impress a structure on the wires and thus also on the entire implant, which it strives to adopt when it is released in the blood vessel system.

The total number of wires at the branch point in the distal direction is expediently at least twelve, preferably at least 24, more preferably at least 32. A corresponding number of wires ensures that the aneurysm is almost completely decoupled from the bloodstream and that thrombus formation takes place within the aneurysm .

Advantageous coverage rates at the branch point in the distal direction for the implant in the expanded state are 45 to 75%, preferably 35 to 65%.

Unless otherwise evident from the context, an expanded state is understood according to the invention to be a state which the implant assumes when it is not subject to any external restrictions. Depending on the diameter of the blood vessels in which the implant is implanted, the expanded state in the blood vessel system can deviate from the expanded state without any external restrictions, because the implant may not be able to assume its fully expanded state. In the fully expanded state, the proximal and distal braided structures advantageously have an outer diameter between 1.5 mm and 7 mm, which can be adapted to the respective location in the blood vessel system. The proximal braid structure often has a larger outer diameter than the distal braid structure because the blood vessel of the stem has a larger diameter than the branching blood vessels. The total length of the implant in the expanded state is usually between 5 mm and 100 mm, in particular between 10 and 50 mm, if the implant is placed in such a way that the two distal braid structures run parallel and in the same direction as the proximal braid structure. The wires forming the implant can, for. B. have a diameter or a thickness between 20 and 60 microns.

On the other hand, the implant can also be in a contracted or compressed state, the terms in the context of this invention being used synonymously in the sense that the implant or the braided structures have a significantly smaller radial extent in the contracted / compressed state than in the expanded state. A contracted / compressed state is e.g. B. assumed when the implant is brought to the target position through a catheter. It is also possible to apply the implant on the outside of a catheter, a tube or the like, in which case the implant is also held in a state that is less radially expanded than in the expanded state.

The terms “proximal” and “distal” are to be understood as denoting parts of the implant that point towards the attending physician (proximal) or parts that point away from the attending physician (distal) when the implant is inserted. The implant is thus typically advanced in the distal direction through or with the aid of a catheter. The term “axial” relates to the longitudinal axis of the implant running from proximal to distal, the term “radial” to planes perpendicular to this.

In order to further improve the closure of the aneurysm, in addition to the decoupling of the aneurysm from the blood flow through the implant, occlusion means, for example coils as are known from the prior art, can also be introduced into the aneurysm. It is also possible to introduce viscous embolizates such as onyx.

The implant according to the invention generally has radiopaque / radiopaque marker elements that facilitate visualization and placement at the implantation site. Such marker elements can, for. B. in the form of wire windings, as sleeves and as slotted pipe sections that are fixed on the implant. In particular, platinum and platinum alloys come into consideration as materials for the marker elements, for example an alloy of platinum and iridium, as is often used in the prior art for marker purposes and as a material for occlusion coils. Other radiopaque metals that can be used are tantalum, gold and tungsten. Another possibility is to fill the wires with an X-ray visible material, as mentioned above. It is also possible to provide the implant, in particular the wires, with a coating made of a radiopaque material, for example with a gold coating. This can e.g. B. have a thickness of 1 to 6 microns. The coating with a radiopaque material does not have to encompass the entire implant. Even if a radiopaque coating is provided, however, it can be useful to additionally apply one or more radiopaque markers to the implant, in particular to the distal end of the implant.

The implant can also have membranes that at least partially cover the mesh structures, it being possible to use both a membrane that extends over larger areas of the mesh structures and a plurality of small membranes. Such a membrane is particularly useful at the neck of the aneurysm in order to cut off the aneurysm from the bloodstream, i.e. to cut off the aneurysm. H. at the branch point in a distal direction.

A cover by a membrane is understood to mean any type of cover, ie the membrane can be on the outside of the Applied braid structure, attached to the inside of the braid structure or the wires of the braid structure are embedded in the membrane.

If one or more membranes are used, it is also possible to introduce X-ray visible substances into the membranes. These can be X-ray-visible particles, such as are usually used as contrast media in X-ray technology. Such radiopaque substances are, for example, heavy metal salts such as barium sulfate or iodine compounds. The X-ray visibility of the membrane is helpful for the introduction and localization of the implant and can be used in addition to or instead of marker elements.

Membranes can also be designed in such a way that they have an antithrombogenic or endothelial-promoting effect. Such an effect is particularly desirable where the implant adjoins normal vessel walls because the blood flow through the vessels is not impaired and, moreover, the implant should be well anchored in the blood vessel system. The membranes can have the appropriate properties by themselves by appropriate selection of the material, but they can also be provided with coatings that produce these effects.

According to the invention, a membrane is understood to be a thin structure with a flat extension, regardless of whether it is permeable, impermeable or partially permeable to liquids. To fulfill the purpose of treating an aneurysm, however, membranes are preferred which are completely or at least largely impermeable to liquids such as blood. In addition, a membrane can also be provided with pores, particularly in the area of the aneurysm neck, through which occlusion means can be introduced into the aneurysm. Another possibility is to design the membrane in such a way that it can be pierced with a microcatheter for the introduction of occlusion means or with the occlusion means itself.

The membranes can be constructed from polymer fibers or films. The membranes are preferably produced by electrospinning. The wires are usually embedded in the membrane. This can be achieved by spinning or braiding the wires with fibers.

In electrospinning, fibrils or fibers are deposited on a substrate from a polymer solution with the aid of an electric current. During the deposition, the fibrils stick together to form a fleece. As a rule, the fibrils have a diameter of 100 to 3,000 nm. Membranes obtained by electrospinning are very uniform. The membrane is tough and mechanically resilient and can be pierced mechanically without the opening becoming a starting point for further cracks. The thickness of the fibrils as well as the degree of porosity can be controlled by selecting the process parameters. In connection with the creation of the membrane and the materials suitable for it, particular reference is made to the WO 2008/049386 A1 , the DE 28 06 030 A1 and the literature cited therein.

Instead of electrospinning, the membranes can also be produced using a dipping or spraying process such as spray coating. With regard to the material of the membranes, it is important that they are not damaged by the mechanical stress when they are introduced into the blood vessel system. The membranes should therefore have sufficient elasticity.

The membranes can be made from a polymer material such as polytetrafluoroethylene, polyester, polyamides, polyurethanes, polyolefins or polysulfones. Polycarbonate urethanes (PCU) are particularly preferred. In particular, an integral connection of the membranes to the wires is desirable. Such an integral connection can be achieved through covalent bonds between the membranes and the wires. The formation of covalent bonds is promoted by silanizing the wires, i. H. by chemical bonding of silicon compounds, in particular silane compounds, to at least parts of the surface of the wires. Silicon and silane compounds bind to surfaces, for example to hydroxyl and carboxy groups. In addition to silanization, other methods of promoting adhesion between wires and membranes are also conceivable.

In this context, a silane compound is to be understood as meaning all those compounds which _{follow the general formula R m} SiX _n (m, n = 0-4) where R stands for organic radicals, in particular alkyl, alkenyl or aryl groups, and X for hydrolyzable groups Groups, in particular OR, OH or halogen where R = alkyl, alkenyl or aryl. In particular, the silane can have the general formula RSiX ₃ . In addition, corresponding compounds with several silicon atoms belong to the silane compounds. In particular, silane derivatives in the form of organosilicon compounds are understood as silane compounds in this context.

As already mentioned above, additional substances promoting endothelial formation can be embedded in the membranes or on the membranes be upset. Since aneurysms are based on degenerative vascular wall diseases, the promotion of endothelial formation and the elimination of functional disorders of the endothelium can have positive effects. This applies in particular to the area where the aneurysm has contact with the bloodstream in the actual blood vessel (stem blood vessel). The substances promoting endothelial formation are preferably applied to the outside of the membrane, the outside being the side of a membrane facing the vessel wall in the implanted state and the inside being the side of a membrane facing away from the vessel wall. Hyaluronic acid, statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) and other polymers can promote colonization with endothelial cells. Polysaccharides, especially glycosaminoglycans, which are able to imitate the glycocalyx, are particularly suitable as polymers. Another material that can be used is POSS-PCU (polyhedral oligomeric silsesquioxane poly (carbonate-urea) urethane). It is a nanocomposite that has been described, among other things, as a framework for artificial organs and as a coating for medical devices ( Tan et al., Crit Rev. Biomed Eng. 2013; 41 (6): 495-513 ). It is also possible to use POSS-PCL (polyhedral oligomeric silsesquioxane poly (caprolactone-urea) urethane). It applies to both POSS-PCU and POSS-PCL that, in particular, functionalized derivatives of these nanocomposites can also be used. This applies in particular to those derivatives that can be obtained by linking with polyacrylic acid (poly-AA). POSS-PCU or POSS-PCL nanocomposite polymers are poorly suited for direct immobilization on the surface of an implant, which is why it has been found to be advantageous to combine polymers such as polyacrylic acid (poly-AA) with the nanocomposite. This can be done, for example, by plasma polymerization of acrylic acid. A poly-AA-g-POSS-PCU surface obtained in this way promotes the binding of collagen (in particular collagen type 1) and thus the formation of endothelium (cf. Solouk et al., Mater Sci Eng C Mater Biol Appl. 2015; 46: 400-408 ). In general, biofunctional or bioactive coatings can be present on the membrane.

The implant according to the invention is particularly suitable for treating intracranial bifurcation aneurysms, but it is also conceivable to use it for other types of aneurysms, for example aortic aneurysms or peripheral aneurysms, the dimensions of the implant being adapted accordingly.

To place the implant in front of the bifurcation aneurysm, a delivery system can be used, as shown in the WO 2018/134097 A1 is described. A further development of this is an insertion system that has a sleeve with two distal sleeve arms, each configured to receive a distal braided structure of the implant and connected to one another, the sleeve having a continuous opening zone in the distal direction and the sleeve having a proximal sleeve arm for receiving the Has the proximal braid structure of the implant, via which the sleeve can be withdrawn in the proximal direction, so that the opening zone opens and the distal braid structures each pass through the opening zone and are released into the branching blood vessels, the opening zone being designed in such a way that the sleeve is upon release of the implant opens sequentially from the distal ends of the distal sleeve arms in the proximal direction. Compared to that in the WO 2018/134097 A1 Such an insertion system differs from the described insertion system in that the implant is released gradually from distal to proximal and can expand accordingly and lean against the vessel wall, which is considered to be advantageous.

The opening zone can be designed in different ways for this purpose. In particular, the opening zone can have a continuous slot from the start, which points in the distal direction, but with the edges of the slot at least partially overlapping. This overlap should increase from the two distal ends of the sleeve arms in a proximal direction. In other words, the respective edges of the slots at the distal ends of the sleeve arms do not overlap or at most slightly overlap where the sleeve arms meet and are connected to one another, whereas the two edges of the slot clearly overlap. Accordingly, the least amount of force is required to release the distal braid structures at the distal ends of the sleeve arms, while this force is relatively high where the sleeve arms meet. The slot thus initially opens at the distal ends of the sleeve arms and the opening continues in the proximal direction, so that the implant in the center is later released. This center corresponds to the point that is typically placed in front of the neck of the aneurysm.

Alternatively, the opening zone can have a weakening zone pointing in the distal direction, the weakening zone being such that the force required for opening increases from distal to proximal. The weakened zone can be reached, for example, via a perforation in which the strength of the webs between the openings increases from distal to proximal and / or the size of the openings increases from proximal to distal. Another possibility is to provide a material thinning or a variation of the material in the area of the weakening zone, so that the Zone of weakness at the distal ends of the sleeve arms first tears open when the sleeve is withdrawn in the proximal direction and the opening of the zone of weakness propagates in the proximal direction, ie to the branching point of the sleeve. The weakened zone is thus designed such that it tears open when the sleeve is withdrawn from the distal ends of the sleeve arms to the connection point of the sleeve arms. In this way, too, a sequential release of the distal braided structures is ensured, in which first the more distal areas are released and expand and only slightly later the more proximal areas.

Another insertion system, with which the implant according to the invention can be placed in front of the aneurysm, has two sleeves that are each configured to receive a distal braided structure of the implant, the two sleeves each having a distal sleeve section and the distal sleeve sections each having a Have longitudinal opening zones, with a proximal section adjoining the distal sleeve sections, via which the sleeves can be retracted in the proximal direction, so that the opening zones open and the distal braided structures each pass through the opening zones and are released in the branching blood vessels . In addition, a stem sleeve is provided which is intended to receive the proximal braid structure of the implant, which is placed in the stem blood vessel. The stem sleeve can be withdrawn in the proximal direction to release the proximal braid structure independently of the sleeves for the distal braid structures or the stem sleeve can be held in order to also release the proximal braid structure of the implant by advancing it in the distal direction. The stem sleeve must therefore continue in the proximal direction, the proximal area not necessarily having to be sleeve-shaped, but z. B. can also consist of a wire or the like.

In this insertion system, a sleeve is provided for each of the two distal braided structures, which are to be placed in one of the blood vessels branching off from the blood vessel of the bloodstream. The sleeve constrains the braid structures and prevents them from radial expansion. At least in the distal area, both sleeves have an opening zone running in the longitudinal direction, through which the distal braid structures can pass and are released when the sleeves are withdrawn in the proximal direction. Alternatively, the release can also take place in that the sleeves are held in place with the aid of the proximal sections, while the implant with the two distal braid structures is advanced in the distal direction. The relative movement between the sleeves and the implant is important for the release, the relative movement of the sleeves acting in the proximal direction, whereas the relative movement of the implant acts in the distal direction. In this context, an advancing device can be used to exert a force on the implant in the proximal direction, either in order to fix it while the sleeves are being pulled in the proximal direction, or in order to advance the implant in the distal direction.

In this context, an opening zone is understood to mean a region of the distal sleeve sections which runs in the longitudinal direction from the distal end of the distal sleeve sections in the proximal direction, typically up to the start of the proximal sections. The opening zones should preferably point in the distal direction in order to facilitate the exit of the distal braided structures. The opening zones must extend in the proximal direction so that an at least sufficiently long section of the implant can be received by the sleeves and the implant is securely held by the insertion system during the insertion. At the proximal ends of the distal sleeve sections, however, the braided structures emerge from the sleeves, while the sleeves have proximal sections that extend further in the proximal direction.

The opening zones can in particular be longitudinal slots through which distal braided structures can pass when the sleeves are withdrawn in the proximal direction. The edges of the longitudinal slots running in the longitudinal direction can abut one another or overlap to a certain extent, it being necessary in each case to ensure that the braided structures can still pass through. In this context, longitudinal direction means that the opening zone must run from the distal end of the distal sleeve sections in the proximal direction, a course with a certain radial component also being understood as “in the longitudinal direction”, for example a helical course.

Instead of providing a longitudinal slot, it is also possible to provide another opening zone in which the longitudinal slot is only created during the release process. For example, it can be a weakened zone in which a perforation is provided which opens when the sleeve sections are withdrawn. Another weakening zone based on a material thinning is also possible.

It is also sensible to provide the opening zone in such a way that the distal braid structures to be released are released from distal to proximal, ie first the two distal ones Ends of the implant until finally the most proximal areas of the distal braid structures, which are located within the sleeve, emerge from the distal sleeve sections. This can e.g. B. can be achieved in that the force to be exerted in the proximal direction for the opening of the opening zone increases from distal to proximal. For example, the resistance of a weakened zone can increase from distal to proximal by increasing the material thickness, using different materials or providing a perforation with intermediate segments increasing in strength in the proximal direction and / or openings increasing in the distal direction. In the case of a longitudinal slot, the overlap of the edges of the longitudinal slot can increase from distal to proximal, which also has the consequence that the distal ends of the implant are exposed first. With the aid of the described insertion system, the individual braid structures of the implant can be released separately by withdrawing the sleeves or the stem sleeve in the proximal direction. At least in the area of the distal sleeve sections, the sleeves are expediently made from a flexible tube material, so that the opening zones can be easily opened and the implant can emerge. The stem sleeve can also be made from a flexible hose material.

Another insertion system that can be used has two distal shaft sections that run through the two distal braid structures, and a proximal shaft section that runs through the proximal braid structure. The three shaft sections are connected to one another adjacent to the branch point of the implant. The distal shaft sections can also be withdrawn in the proximal direction via the proximal shaft section. The distal braid structures are releasably attached to the distal shaft sections so that the distal braid structures assume their expanded structure after the attachment has been released and are released in the branching blood vessels.

In the case of this insertion system, the implant is therefore not brought to the desired location within a sleeve, but rather is fixed on the shaft sections of the insertion system. In other words, the implant is brought to the desired location on the delivery system. As soon as the correct placement has taken place, the fixation of the implant on the shaft sections is released. The implant then expands and rests against the inner wall of the vessel, with the two distal braided structures resting against the inner wall of the two branching blood vessels.

The attachment points between the distal braid structures and the distal shaft sections are expediently arranged at least at the distal ends of the implant. As soon as the attachment points at the distal ends are loosened, the expansion of the implant begins. Further attachment points further proximally are also possible, but these are not absolutely necessary because the release further proximally can also be controlled via a microcatheter surrounding the implant including the insertion system.

The shaft sections can in particular be constructed from a flexible hose material, which has the advantage that the implant rests well against the hose material and an additional frictional connection is established between the implant and the hose material. In principle, however, a metallic shaft, on which the implant is applied and fixed, is also conceivable, for example.

The shaft sections expediently have an inner cavity, because this enables one or more guide wires to be passed through, via which the insertion system can be brought to the desired location. In particular, several guide wires can also be used, one of which is guided into the first and the other into the second branching vessel, for example, in order to be able to advance the insertion system to the desired location.

The fixing points can be connection points at which there is a chemically, thermally, electrolytically or mechanically detachable connection. The loosening of the connection points can be controlled accordingly by setting the corresponding parameters.

Chemically, thermally or electrolytically detachable connection points are understood to mean connection points which can be dissolved by chemical or thermal action or electrolytically by applying an electrical voltage at least to such an extent that the respective braid structure of the implant detaches from the shaft section.

The connection points can be adhesive connection points, a polymer adhesive preferably being used. In this case, the implant is detached chemically, namely typically by applying a solvent which at least partially dissolves the adhesive. As a solvent, for. B. DMSO (dimethyl sulfoxide) can be used. A chemically releasable connection point is also understood to mean a connection point which is released solely through the action of the surrounding blood.

Another possibility is the electrolytic detachment of the connection points. the In this case, the connection point is at least partially dissolved by applying an electrical voltage. The electrolytic detachment of implants is well known from the prior art. For example, stainless steel, magnesium, magnesium alloys or cobalt-chromium alloys are suitable as materials for the connection point to be electrolytically dissolved. A particularly preferred magnesium alloy is Resoloy ^® , which was developed by MeKo from Sarstedt / Germany (cf. WO 2013/024125 A1 ). It is an alloy of magnesium and, among other things, lanthanoids, especially dysprosium. Another advantage of using magnesium and magnesium alloys is that magnesium residues remain in the body without physiological problems.

In the case of a thermally detachable connection point, a heat source can be brought to the connection points to be detached in order to detach the implant.

Another possibility of defining the braided structures provided for placement in the branching blood vessels on the shaft sections is to place caps on the distal ends of the distal braided structures which prevent the braided structures from expanding radially. These caps can be removed from the distal ends in the distal direction, in particular they can be pushed off, in order in this way to release the implant.

The caps can in particular have a cylindrical design, the distal end of the caps generally being largely closed, apart from a small opening for the passage of a wire, as described further below. The inner diameter of the caps must be such that expansion and release of the distal braided structures is prevented when the cap is in place.

The detachment of the caps can in particular be brought about by guiding push wires at least temporarily through the inner cavities of the distal shaft sections. These push wires are designed in such a way that the advancement of the push wires in the distal direction causes the caps to be pushed off the distal ends of the implant. For this purpose, the push wires can, for example, have thickenings that are attached at or near the distal end.

Particularly preferred is the provision of push wires, which run through openings provided for this purpose in the caps, the push wires having thickenings distal and proximal to the openings and the thickening of a push wire located further proximally ensuring that the thickening is attached to the distal when advancing in the distal direction On the inside of the cap and pushes it off the implant when further force is exerted, while the distal thickenings ensure that the push wires are held in their positions and do not slip out of the openings in the caps. The thickenings should have a diameter which is larger than the diameter of the openings in the caps provided for the push wires, since otherwise the push wires could be detached from the caps. In particular, the thickenings can be spherical.

When using one of the described delivery systems or any other delivery system, the implant and delivery system can be brought to the target position via a microcatheter.

In addition to the implant itself, the invention also relates to the use of the implant for the treatment of arteriovenous malformations, in particular (bifurcation) aneurysms, and the combination of the implant with an insertion system and possibly a microcatheter. All statements made about the implant itself also apply in a corresponding manner to the use of the implant and a method for using the implant.

The invention is explained in more detail by way of example with the aid of the figure. It should be pointed out that the figure shows a preferred embodiment variant of the invention, but the invention is not restricted thereto. In particular, as far as it is technically sensible, the invention includes any combination of the technical features that are listed in the claims or described in the description as being relevant to the invention.

• 1 Ein erfindungsgemäßes Implantat in der Seitenansicht.

It shows:

• 1 An implant according to the invention in a side view.

In 1 becomes the implant according to the invention 1 shown in the side view. It has a first braid structure 2 on that at the junction point 7th into a second braid structure 3 and a third braid structure 4th transforms. For the sake of simplicity of illustration, the implant 1 here as from eight wires 5 shown constructed, actually lies the number of wires 5 usually significantly higher. The wires 5 form a braid, whereby the wires 5 at crossing points 6th cut and be brought over and under each other. Wires 5 in the foreground are shown as solid lines, wires 5 dashed in the background. By doing that part of the wires 5 into the second braid structure 3 , another part, however, in the third braid structure 4th passes is the total number of the wires 5 in the two braid structures 3 , 4th only half as large as in the first braid structure 2 . The first braid structure 2 , which can be anchored in the main blood vessel, but also in one of the branching blood vessels, has a larger diameter than the other two braided structures 3 , 4th .

It is also important for the invention that on the distal side or in the distal area of the branching point 7th adjacent to the bifurcation aneurysm to be treated, a sufficiently large number of wires 5 is available. There are wires at this point as well 5 that cover the neck of the aneurysm and prevent blood from entering the aneurysm. In fact, the number of wires lies 5 at this point 7th considerably higher than shown here, since normally the total number of wires 5 is higher than in the simplified representation with only eight wires 5 so that, overall, a sufficiently good coverage of the aneurysm neck is guaranteed

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• WO 2012/113554 A1 [0007]
• WO 2014/029835 A1 [0007]
• US 2004/0220653 A1 [0008]
• WO 2008/049386 A1 [0043]
• DE 2806030 A1 [0043]
• WO 2018/134097 A1 [0049]
• WO 2013/024125 A1 [0066]

Non-patent literature cited

• Tan et al., Crit Rev. Biomed Eng. 2013; 41 (6): 495-513 [0047]
• Solouk et al., Mater Sci Eng C Mater Biol Appl. 2015; 46: 400-408 [0047]

Claims (15)

Implant for influencing the blood flow in the area of aneurysms that are localized at branching vessels, the implant (1) being in an expanded state in which it is implanted in the blood vessel and in a contracted state in which it can be moved through the blood vessel , the implant (1) has a first braid structure (2) which is tubular in the expanded state and the wall of which is made up of individual interwoven wires (5), the first braid structure (2) at a branching point ( 7) branches into a second and a third braid structure (3, 4), the second and the third braid structure (3, 4) being tubular in the expanded state and their walls being made up of individual interwoven wires (5), characterized in that, that part of the wires (5), which form the first braid structure (2), at the branching point (7) into the second e braid structure (3) merges, and another part of the wires (5) that form the first braid structure (2) merges into the third braid structure (4) at the branching point (7). Implant after Claim 1 , characterized in that the first half of the wires (5) which form the first braid structure (2) and are present at the branching end of the first braid structure (2) merges into the second braid structure (3) at the branch point (7), and the The second half of the wires (5) that form the first braid structure (2) and are present at the branching end of the first braid structure (2) merges into the third braid structure (4) at the branching point (7). Implant after Claim 1 or 2 , characterized in that of two wires (5) which form a crossing point (6) at the branching end of the first braid structure (2), one wire (5) into the second (3) and one wire (5) into the third braid structure (4) passes. Implant after Claim 1 or 2 , characterized in that two wires (5), which form a first intersection point (6) at the branch end of the first braid structure (2), merge into the second braid structure (3), and two wires (5) each, which at the branch end of the first braid structure (2) form an intersection point (6) adjacent to the first intersection point (6), merge into the third braid structure (4). Implant according to one of the Claims 1 until 4th , characterized in that the number of wires (5) which form the first braid structure (2) is 24 to 96. Implant according to one of the Claims 1 until 5 , characterized in that the implant (1) is subjected to a shaping process which increases the number of wires (5) at the branching point (7) in the distal direction. Implant after Claim 6 , characterized in that the shaping process is a heat treatment. Implant according to one of the Claims 1 until 7th , characterized in that the number of wires (5) at the branch point (7) in the distal direction is 12, preferably 24, more preferably 32. Implant according to one of the Claims 1 until 8th , characterized in that the implant (1) in the expanded state at the branching point (7) has a coverage rate of 25 to 75%, preferably 35 to 65%, in the distal direction. Implant according to one of the Claims 1 until 9 , characterized in that the wires (5) are at least partially made of a material with shape memory properties. Implant after Claim 10 , characterized in that the material with shape memory properties is a nickel-titanium alloy. Implant after Claim 10 or 11th , characterized in that the wires (5) have a core made of a X-ray visible material and a sheath made of a material with shape memory properties. Implant according to one of the Claims 1 until 12th , characterized in that the implant (1) has radiopaque markers. Implant according to one of the Claims 1 until 13th , characterized in that the implant (1) has one or more membranes which at least partially cover the braided structures (2, 3, 4). Implant after Claim 14 , characterized in that the membrane has an antithrombogenic or endothelial-promoting effect.

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