Implant for the treatment of aneurysms in the region of bifurcations - Patent application

Abstract

The present invention relates to an implant (1) for influencing the blood flow in the region of an aneurysm localized at a vascular bifurcation of a blood vessel, the implant (1) being present in an expanded state in which it is embedded in a blood vessel and in a contracted, elongated state in which it is movable through a vessel or a catheter, the implant (1) having at least three parts (2, 3) that are tubular at least in the expanded state, the wall of which is made up of braided wires (4) or interconnected struts, at least two tubular parts (3) branching off from a first tubular part (2), the at least three tubular parts (2, 3) being constructed individually and each connected to each other at one end so as to ensure, in the expanded state, the blood flow through the first tubular part (2) to the tubular parts (3) branching off from the first tubular part (2). The implant (1) proposed by the present invention allows to achieve a targeted coverage of the aneurysm neck without the implant (1) expanding radially causing interference with wire or strut structures in the region where the tubular parts (2, 3) branch off.

Description

[Technical field]

[0001] The present invention relates to an implant for influencing blood flow in the region of an aneurysm located at a vessel bifurcation, this type of aneurysm also referred to as a bifurcation aneurysm. [Background technology]

[0002] Aneurysms are usually saccular or fusiform dilations of the blood vessel wall, which occur mainly in areas of the vessel wall that have been structurally weakened by the constant pressure acting on the vessel wall. The inner wall of the vessel in an aneurysm is therefore sensitive and prone to damage. The rupture of an aneurysm usually causes serious health problems, and in the case of cerebral aneurysms, can even cause neurological disorders and death of the patient.

[0003] Besides surgical procedures, in which the aneurysm is clamped, for example, by clips, intravascular methods are known in particular for the treatment of aneurysms, with two main approaches being pursued. 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 occlusion of the aneurysm. On the other hand, it is known to block access to the aneurysm, for example the neck of a pincushion aneurysm, from the vascular side with a stent-like implant, thus isolating the aneurysm from the blood flow. Both methods serve to reduce the blood flow into the aneurysm, thus reducing, ideally eliminating, the pressure acting on the aneurysm and thus reducing the risk of aneurysm rupture.

[0004] When filling an aneurysm with coils, it may happen that the aneurysm is insufficiently filled, which allows blood to flow into the aneurysm and maintains the pressure acting on its inner wall. The risk of the aneurysm continuing to expand and eventually burst is still present, even in a weakened form. Moreover, this method of treatment is mainly suitable for aneurysms with a relatively narrow neck, the so-called needle aneurysms - otherwise there is a risk that the coil will protrude from the wide aneurysm neck into the blood vessel, form a thrombus there and cause an obstruction in the blood vessel. In the worst case, the coil will flow out of the aneurysm completely and obstruct the blood vessel at another position. In order to hold the coil in place in the aneurysm sac, the neck of the aneurysm is often additionally covered with a special stent.

[0005] Another endovascular treatment approach focuses on so-called flow diverters. These implants are similar in appearance to stents used to treat stenoses. However, since the purpose of these flow diverters is not to open the vessel but to block access to the aneurysm on the vessel side, the mesh width is very narrow; alternatively, this type of implant is covered with a membrane. The disadvantage of these implants is the risk that sometimes the exit side branches in the immediate vicinity of the aneurysm to be treated are also covered and thus may be occluded in the medium to long term.

[0006] Vascular bifurcations, especially vessel bifurcations, are a very frequent phenomenon. If the vessel wall is weak, the blood flow through the artery and acting on the front wall of the bifurcation quickly creates a protuberance or bulge, which then expands more rapidly. Such bifurcation aneurysms often have a wide neck, which makes them difficult to treat using occlusion coils alone.

[0007] Vascular implants suitable for providing such a "latticing" of the aneurysm entrance in the region of the vessel bifurcation are disclosed, for example, in US Pat. No. 5,399,623 or US Pat. No. 5,499,636. The aneurysm can be rendered non-critical by an occlusion coil that is inserted after the implant is in place. It is also possible that the implant itself sufficiently isolates the aneurysm from the blood flow. For this purpose, for example, the implant can have a membrane that is placed in the region of the aneurysm neck or in front of it. If considered useful or expedient, the blood flow to the aneurysm can be reduced using only filaments, typically small diameter wires or membranes, to such an extent that the additional introduction of occlusion coils or other occlusion means into the aneurysm can be omitted.

[0008] US Patent No. 5,399,633 describes a flow diverter system and associated insertion system for treating bifurcated aneurysms. In the expanded state, the flow diverter or bifurcated stent has three tubular sections forming the arms of the flow diverter, two of which are intended to be placed in the branch vessels branching off from the first section, which is placed in the parent vessel supplying the blood. A Y-shaped structure is thus created.

[0009] However, it has proven to be problematic, especially in the case of flow diverters with three arms made of braided wire, that the wires forming the braid have different lengths in the area where the arms are connected to each other. When such an implant is brought into a compressed elongated state for insertion into a catheter, the braided structure is destroyed, especially in the connection area of ​​the three arms. Thus, after re-expansion, a uniform surface coverage is not obtained, especially in the area where the aneurysm should be covered and isolated from the blood flow. [Prior art documents] [Non-patent literature]

[0010] [Patent Document 1] International Publication No. 2012 / 113554 [Patent Document 2] International Publication No. 2014 / 029835 [Patent Document 3] International Publication No. 2018 / 134097 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, based on the prior art discussed above, the object of the present invention is to provide an implant that can be used for the treatment of branched arteries, which can be easily compressed and stretched into a shape for insertion through a catheter, and which can achieve a uniform surface coverage after expansion at the target location, especially in the region of the aneurysm neck. [Means for solving the problem]

[0012] As proposed by the invention, this object is achieved by an implant for influencing the blood flow in the region of an aneurysm localized at a vascular bifurcation of a blood vessel, the implant existing in an expanded state in which it is embedded in the blood vessel and in an elongated state with reduced diameter in which it is movable through a vessel or a catheter, the implant having at least three parts which are tubular at least in the expanded state, the walls of which are made up of braided wires or interconnected struts, at least two tubular parts branching off from a first tubular part, the at least three tubular parts being individually constructed and each connected to one another at one end so that in the expanded state, blood flow is ensured through the first tubular part to the tubular parts branching off from the first tubular part.

[0013] The invention is based on the finding that the properties of the implant as a whole can be improved if the tubular parts that serve as arms of the implant are initially manufactured separately and then connected to one another at the end of each arm, resulting in an implant in which at least two further tubular parts branch off from the first tubular part. In most cases, the implant is composed of a total of three tubular parts, each forming an arm of the implant. By initially forming the three tubular parts separately, it is ensured that these tubular parts can be easily transferred to a reduced diameter elongated state and to an expanded state without destroying the braided structure in the area where they adjoin one another. The connections between the tubular parts are therefore only formed at a later time, whereby the connections are designed in such a way that the structure in the connection area is not adversely affected by the expansion or compression of the implant. This means that the purely tubular parts can be expanded and compressed without problems, while the area where the parts branch off from one another is not adversely affected by this, and instead the wires or struts can achieve a targeted, ideally predefinable, appropriate surface coverage, as desired for the respective application. In this regard, the area of ​​branching is particularly important, since this is where the aneurysm neck is usually located. A bifurcated implant typically has a first tubular portion placed within a parent vessel and a branching tubular portion placed within the branch vessel, and the aneurysm typically forms between the two branch vessels, such that the region of the implant anterior to the aneurysm is exactly where the two tubular portions branch off from the first tubular portion.

[0014] In this context, "bifurcations" are understood to denote any transition from one tubular section to another. The bifurcations may be direct or indirect, i.e. a tubular section may be directly adjacent to another tubular section, or an intermediate section, in particular a central connecting element as described below, may be located between the two tubular sections. What is important with regard to the bifurcation location is only that there is eventually a transition from the first tubular section to a further tubular section, even if the intermediate section is still located between the tubular sections. In the expanded state, it must be ensured that blood flow is maintained through the first tubular section to the bifurcated tubular section.

[0015] The implant proposed by the present invention is suitable for largely or completely isolating from the blood flow a branch artery located at the bifurcation between the tubular parts, due to the fact that at least a part of the wire or strut is located in front of the aneurysm neck. It should be noted that the blood flow through the parent vessel in which the first tubular part is located and the branch vessel in which the other two tubular parts are located remains substantially unaffected. As a result, due to the lack of blood movement within the aneurysm, the aneurysm shrinks and a thrombus forms, occluding the aneurysm.

[0016] According to an advantageous embodiment of the invention, at least three tubular sections meet at a central connecting element, by means of which the tubular sections are connected to one another. As already mentioned, there are usually three tubular sections in total, namely a first tubular section placed in the parent vessel and two additional tubular sections for the branch vessels. However, the individual tubular sections are not directly connected to one another, but are indirectly connected via a central connecting element, which typically has a structure different from that of the tubular sections themselves. In particular, the connecting element may be a laser-cut structure, while the tubular sections may be designed to consist of a braided structure of interwoven wires. However, the tubular sections may also consist of struts that are laser-cut and correspondingly connected to one another. The properties of the central connecting element, which is typically placed just before the aneurysm neck, can be adjusted as required without directly interfering with the properties of the tubular sections.

[0017] The connecting element may consist of a number of struts connected to one another. Typically, such structures are manufactured using laser cutting. The connecting element may expediently have a Y-shaped structure, with each arm of the Y-shaped structure being connected to one of the tubular parts. The connecting element thus has three arms, each of which merges into a tubular part. The structure of the connecting element is thus adapted to the structure of the entire implant, which in principle also forms a Y-shaped structure.

[0018] Conveniently, the interconnected struts of the connecting elements have the same length in the reduced diameter, elongated state of the implant, ensuring that during expansion / compression, undesirable deformation of areas of the implant that are important for effective coverage of the aneurysm neck does not occur.

[0019] The connection between each tubular part and the connecting element can be made in various ways. One possibility is to fasten or attach the tubular part to the connecting element by wire or thread, typically one part on each arm of the Y-shaped structure. Another option is to form a fusion or inter-material joint between the tubular part and the connecting element or one arm of the Y-shaped structure. Fusion joints include in particular welding, but other integral joining methods such as gluing or soldering are also conceivable in principle.

[0020] It is considered advantageous if the connection elements have a laser cut structure. For implants such as flow diverters or stents, a distinction is usually made between braided structures made of individual wires and laser cut structures. However, other manufactures of implants are also fundamentally conceivable, such as additive methods, in which the structure is built up by gradually adding material. Such additive methods are in particular 3D printing.

[0021] The connecting element may comprise one or more membranes at least partially covering the connecting element, which membranes are arranged to completely or partially prevent blood from entering or leaving the connecting element, in this way a particularly effective covering of the aneurysm neck is obtained, so that the aneurysm is largely or completely cut off from the blood flow, there is no risk of the aneurysm rupturing and the aneurysm shrinks.

[0022] Covering with a membrane is understood to mean any kind of covering, i.e. the membrane may be applied to the outside of the connecting element, may be attached to the inside of the connecting element or the struts or wires of the connecting element may be embedded in the membrane.

[0023] Instead of using a central connecting element, it is also possible to connect the at least three tubular parts directly to one another by wires and / or threads. Another option is to attach the at least three tubular parts to one another by fusion / inter-material bonding, where fusion in particular means welding. Furthermore, other inter-material bonding methods such as the above-mentioned soldering or gluing are also conceivable in principle.

[0024] In this embodiment of the invention, therefore, the central connecting element is omitted and the tubular parts directly abut and are connected to one another as arms of the implant. Nevertheless, by constructing the individual tubular parts separately, it is ensured that the expansion and compression of the tubular parts can be carried out without adversely affecting the structure of the transition areas between the individual tubular parts.

[0025] If wires and / or threads are used to join the tubular sections to one another or to the connecting elements, they can be at least partially radiopaque to allow visualization by the attending physician. In particular, wires made of radiopaque materials such as platinum, platinum-iridium or similar radiopaque metals and alloys can be used.

[0026] The wires that connect the tubular sections together may be separate wires that are applied in addition to the tubular sections. Another option is to form the connections with wires that are part of the tubular sections themselves or that protrude from the tubular sections. These wires are linked or braided together to establish the connections between the tubular sections.

[0027] The tubular portion may also have one or more membranes at least partially covering said portion. In this way, blood flow through the wall of the tubular portion is partially or completely blocked. This may further help to isolate the aneurysm from the blood flow, especially if the membrane is located near a bifurcation between the tubular portions. Thus, it is possible to provide a membrane in an area of ​​the tubular portion located near the bifurcation, whereas an area located away from the bifurcation does not.

[0028] With regard to the membrane, what has been stated above with regard to the membrane of the connecting element applies, i.e. covering with a membrane is understood to mean any type of covering: the membrane is applied to the outside of the tubular part or is arranged on the inside of the tubular part or the wires or struts of the tubular part are embedded in the membrane.

[0029] There may be membranes extending over a larger area, both in the region of the connecting element and in the tubular portion, or multiple membranes covering different areas may be provided. One option is to introduce radiopaque substances into the membrane. These may be radiopaque particles, such as those normally used as contrast agents for radiotechnical purposes. Such radiopaque substances are, for example, heavy metal salts, such as barium sulfate, or iodine compounds. Radiopaque membranes prove to be beneficial during placement and for localization of the implant, and can be used in addition to or instead of marker elements.

[0030] The membrane can also be designed to have an anti-thrombotic effect or an effect that promotes endothelialization. Such an effect is particularly desirable when the implant is adjacent to a normal vessel wall, since blood flow through the vessel should not be compromised and yet good fixation of the implant within the vasculature should be achieved. The membrane can have the desired properties by itself by appropriate selection of materials, but can also be provided with a coating that produces the desired effect.

[0031] In the sense of the present invention, a membrane is a thin structure with a flat surface, regardless of whether the structure is permeable, impermeable or partially permeable to liquids. However, to achieve the goal of treating the aneurysm, it is preferred that the membrane is completely or at least substantially impermeable to liquids such as blood. Furthermore, the membrane may be provided with holes, particularly in the region of the aneurysm neck, through which an occluding agent can be introduced into the aneurysm. Another option is to design the membrane so that it can be penetrated by a microcatheter for introducing the occluding agent or by the occluding agent itself.

[0032] The membrane may be made of polymer fibers or polymer films. Preferably, the membrane is manufactured by electrospinning. In this process, wires / struts are usually embedded in the membrane. This can be achieved by weaving or knitting the wires / struts with the fibers.

[0033] In electrospinning, fibrils or fibers from a polymer solution are deposited on a substrate using an electric current. This deposition causes the fibrils to aggregate into a nonwoven fabric. Usually, the fibrils have a diameter in the range of 100-3000 nm. The membranes created by electrospinning have a very uniform texture. They are robust, withstand mechanical stresses and do not allow cracks to propagate through the openings even when mechanically penetrated. The thickness of the fibrils and the degree of porosity can be controlled by a suitable selection of the process parameters. In the context of the production of membranes and in relation to materials suitable for this purpose, special attention is drawn to WO 2008 / 049386, DE 2 806 030 A1 and the literature mentioned therein.

[0034] Instead of electrospinning, the membrane can also be manufactured by a dipping or spraying process, for example spray coating. It is important for the material used for the membrane to not be damaged by the mechanical stresses that arise when the implant is inserted into the vasculature. For this reason, the membrane should have sufficient elasticity.

[0035] The membrane can be made of polymeric materials such as polytetrafluoroethylene, polyester, polyamide, polyurethane, polyolefin or polysulfone. Polycarbonate urethane (PCU) is particularly preferred. In particular, an integral connection between the membrane and the wire / strut is desired. Such an integral connection can be achieved by a covalent bond provided between the membrane and the wire / strut. The formation of the covalent bond is promoted by silanization of the wire / strut, i.e. by chemically bonding silicon compounds, in particular silane compounds, to at least a portion of the surface of the wire / strut. On the surface, silicon and silane compounds bond, for example, to hydroxy and carboxy groups. In principle, other methods of mediating adhesion between the wire / strut and the membrane besides silanization are also conceivable.

[0036] In this context, silane compounds are compounds of the general formula R m Six n (m, n=0-4), where R represents an organic radical, in particular an alkyl, alkenyl or aryl group, and X represents a hydrolyzable group, in particular OR, OH or halogen, with R=alkyl, alkenyl or aryl. In particular, silanes are of the general formula RSiX 3 In addition, related compounds having multiple silicon atoms are also considered to belong to the silane compounds. In particular, silane derivatives in the form of organosilicon compounds are understood as silane compounds in this context.

[0037] As already mentioned above, additional substances that promote endothelialization may be embedded in or deposited on the membrane or the membrane or the wires / struts. Since aneurysms result from degenerative diseases of the vessel wall, promotion of endothelialization and correction of endothelial dysfunction may have beneficial effects. This is particularly true in the area where the aneurysm comes into contact with the blood flow in the respective vessel (parent vessel). Preferably, the substances that promote endothelialization are applied to the outside of the membrane, outside being understood to mean the side of the membrane that faces the vessel wall in the implanted state, and inside being understood to mean the side of the membrane opposite the vessel wall. Hyaluronic acid, statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) and other polymers can promote endothelial cell colonization. Polysaccharides, especially glycosaminoglycans that can mimic the glycocalyx, are particularly suitable polymers. Another usable material is POSS-PCU (polyhedral oligomeric silsesquioxane poly(carbonate-urea)urethane). It is a nanocomposite, which has been described in particular as a scaffold for artificial organs and as a coating for medical devices (Tan et al., Crit Rev. Biomed Eng. 2013; 41(6): 495-513). The use of POSS-PCL (polyhedral oligomeric silsesquioxane poly(caprolactone-urea) urethane) is also possible. This applies to both POSS-PCU and POSS-PCL, but in particular to functionalized derivatives of these nanocomposites. This applies in particular to the derivatives obtained by coupling with polyacrylic acid (poly-AA). Since the POSS-PCU and / or POSS-PCL nanocomposite polymers are not very suitable for direct immobilization on the surface of the implant, it has proven advantageous to combine a polymer such as polyacrylic acid (poly-AA) with the nanocomposite. This can be achieved, for example, by plasma polymerization of acrylic acid. The poly-AA-g-POSS-PCU surface thus obtained promotes collagen binding, especially type I collagen, and thus endothelial formation (see Solouk et al., Mater Sci Eng C Mater Biol Appl. 2015;46:400-408).Generally, a biofunctional or bioactive coating may be present on the membrane.

[0038] At least two tubular sections branching off from the first tubular section may have a smaller diameter in the expanded state than the first tubular section. On the one hand, this is due to the fact that branching vessels often exhibit a smaller inner diameter than the parent vessel. On the other hand, the smaller diameter of the branching tubular sections ensures a stress-free connection with the first tubular section.

[0039] The walls of the tubular parts may be formed from interwoven wires. In this connection, it is also conceivable to braid at least some of the tubular parts in such a way that there are no free wire ends at at least one end of the respective tubular part. The tubular parts at this end are therefore braided in a closed manner against the periphery of the wall. This means that the interwoven wires do not end freely here but are returned in the opposite direction into the braid.

[0040] The tubular parts can be designed, for example, such that each tubular part has an end with free wire ends and an end without free wire ends. In other words, each tubular part is braided at one end in an open state and at the other end in a closed state, the open and closed states in this case referring to the periphery and not to the lumen of the tubular part. The tubular parts in this case preferably converge at the end without free wire ends (i.e. braided in a closed state). There, it may be connected to a central connecting element or directly to other tubular parts. In this connection, the wires constituting the tubular parts can be used directly to form a connection with the connecting element or the remaining tubular parts, in particular by interweaving the wires with the struts of the connecting element or with the wires of other tubular parts.

[0041] With regard to the braided tubular portion, the braid can be braided in basically any known manner. It may have a single and / or multiple structure. When used in a particularly tight braid configuration, a tight braid leads to high stress on the individual wires. However, while a multiple design is effective in removing tension from the braid, on the other hand, a braid configuration that is too tight leads to deterioration of the bonds in the braid. The braiding method indicates the number of times a given wire passes through such wire on the same side of the crossing wire before changing sides, and then passes through a corresponding number of crossing wires on the opposite side. For example, in the case of a double arrangement, the wire passes over two crossing wires in succession, and then along the underside of the two crossing wires in succession. In a single structure, the wires are arranged alternately one above the other.

[0042] In particular, multi-ply wires may also be used. The ply method indicates the number of individual wires arranged in parallel that are joined. Single or multiple plies may comprise one or more individual wires running in parallel. As the wires are introduced into the process from bobbins during the braid manufacturing process, one or more individual wires are fed simultaneously from their respective bobbins to the mandrel on which the braid is manufactured. Each wire may be constructed from a single wire or from a strand that includes multiple individual wires that are joined and preferably twisted together.

[0043] A ply of two or more ply configuration provides a higher surface density of the braid while at the same time reducing longitudinal expansion when the braid is compressed. However, such a higher surface density also reduces flexibility due to increased friction and tension. This can be countered by using a more highly braided arrangement, i.e., a double or higher order braid structure results in greater flexibility.

[0044] The total number of wires forming the tubular portion is preferably 24 to 96, which creates a dense mesh structure that conforms well to the inner wall of the blood vessel. Apart from this, the large number of wires ensures good surface coverage and braid density in the area of ​​the aneurysm.

[0045] Filaments of various shapes can be used as wires or struts. They can have a circular, elliptical or even angular cross section, in particular a rectangular, square or trapezoidal cross section, and in the case of an angular cross section, the edges can be rounded. The use of struts in the form of flat wires or thin strips is also possible. Individual wires can also be made from a number of individual filaments twisted together or running parallel to one another. The wires or struts can be solid or hollow inside. Furthermore, the wires / struts can be subjected to electropolishing to make them smoother, rounder and therefore less traumatic. This reduces the risk of bacteria or other impurities attaching.

[0046] Preferably, the wires or struts are made of metal, but in principle it is also conceivable to use wires made of other materials, for example plastic or polymeric materials, such filaments being also understood as wires or struts according to the invention.

[0047] To ensure that the implant automatically expands and conforms to the inner wall of the blood vessel, for example when released or released from the catheter or out of the catheter, it is preferable to make the implant at least partially from a material with shape memory properties. In this connection, nickel-titanium alloys, such as Nitinol, or ternary nickel-titanium-chromium alloys or nickel-titanium-copper alloys are particularly preferred. However, other shape memory materials, such as other alloys or shape memory polymers, are also conceivable. A material with shape memory properties makes it possible to give the implant a secondary structure that it will automatically adopt as soon as its expansion is no longer hindered. The use of cobalt-chromium or cobalt-chromium-nickel alloys is also possible.

[0048] It is also possible to use so-called DFT® (drawn filled tubing) wires or struts, i.e. wires / struts whose core is made of a different material than the sheath surrounding the core. In particular, it is expedient to use wires / struts with a core of radiopaque material and a sheath of a material with shape memory properties. The radiopaque material may be, for example, platinum, a platinum-iridium alloy or tantalum, while the material with shape memory properties is, as mentioned above, preferably a nickel-titanium alloy. DFT filaments of this kind are offered, for example, by Fort Wayne Metals.

[0049] Each wire or strut combines the advantageous properties of two materials: the sheath with shape memory properties ensures that the implant expands and conforms to the vessel wall, while the radiopaque material ensures that the implant is visible in radiographs and can therefore be observed by the attending physician and positioned as needed.

[0050] The distal and proximal ends of the wires or struts are preferably configured to prevent damage to the vessel wall. For example, the wires / struts may be rounded at their ends and thus atraumatic. Appropriate shaping can be achieved by remelting with a laser. It is also possible to join one or more wires / struts at each end, thus creating an appropriately shaped atraumatic termination. In particular, it is advisable and expedient to avoid sharp wire ends.

[0051] In the case of laser cut tubular sections, or more generally tubular sections composed of interconnected struts, both open and closed cell structures can be used. Closed cell structures usually allow easier repositioning or even complete replacement of the implant during an intervention. On the other hand, open cell structures better adapt to the pathways of the vascular anatomy.

[0052] To further increase the surface coverage in the region of the aneurysm neck, the implant can undergo a shaping process during manufacture to increase the number of wires or struts at the branching point in the distal direction. This is particularly important in embodiments where no connecting elements are arranged between the tubular parts. The branching point facing the distal direction typically corresponds to the aneurysm neck, so that an increase in the number of wires / struts at this position allows the aneurysm neck to be covered to a greater extent and therefore to be more effectively decoupled from the blood supply. A suitable shaping process may be of a mechanical nature, but in particular at least a heat treatment that ensures that the implant, in the expanded state, comprises a large number of wires or struts at the branching point in the distal direction. Such a heat treatment is particularly expedient for wires or struts made of shape memory material, since it allows the wires, and therefore also the entire implant, to be given the structure that the implant is intended to adopt upon release in the vasculature.

[0053] In the expanded state of the implant, advantageous coverage at the distal bifurcation site is 25-75%, preferably 35-65%.

[0054] Unless the context indicates otherwise, the term expanded state in the sense of the present invention is understood to indicate the state that the implant assumes when it is free from external constraints. Depending on the diameter of the vessel in which the implant is placed, the expanded state in the vasculature may differ from the expanded state that exists in the absence of external constraints, since the implant may not be able to assume a fully expanded state. In the fully expanded state, the tubular parts advantageously have an outer diameter of 1.5 mm to 7 mm, said diameter being adaptable to the respective target site in the vasculature. In many cases, due to the fact that the diameter of the parent vessel is larger than that of the branch vessel, the first proximally located tubular part has a larger outer diameter than the more distally located tubular part. The total length of the implant in the expanded state is usually between 5 mm and 100 mm, and between 10 and 50 mm, in particular when the implant is placed such that the two distally located tubular parts have a parallel configuration and extend in the same direction as the proximal tubular part. The wires or struts forming the implant may have a diameter or thickness of, for example, between 20 and 60 μm.

[0055] On the other hand, the implant may be in a contracted, elongated state, also called a contracted or compressed state, and in the context of the present invention, the terms are used synonymously in the sense that the respective tubular portion of the implant has a significantly smaller radial extent in the contracted state than in the expanded state. The elongated, contracted / compressed state is assumed, for example, when the implant is delivered to the target site by a catheter. The implant may also be attached to the outside of a catheter, tube or similar item, in which case the implant is also held in a less radially expanded state compared to the expanded state.

[0056] With respect to the implant placement process, the terms "proximal" and "distal" should be understood to refer to the portion of the implant that faces toward the physician (proximal) or, in some cases, the portion that faces away from the physician (distal). Typically, the implant is advanced distally by or with a catheter. The term "axial" refers to the longitudinal axis of the implant extending from proximal to distal, and the term "radial" refers to the direction perpendicular thereto.

[0057] To further improve occlusion of the aneurysm, in addition to isolating the aneurysm from the blood flow with an implant, an occluding agent may be introduced into the aneurysm, for example, a coil as known in the art. Viscous embolic agents may also be introduced.

[0058] The implants proposed by the invention are usually provided with radiopaque marker elements that facilitate visualization and positioning accuracy at the placement site. For example, such marker elements may be provided in the form of wire coils, sleeves and slotted tube sections that are fixed to the implant. As said marker elements, in particular platinum and platinum alloy materials, for example alloys of platinum and iridium, are suitable, since they are often used according to the prior art for marking purposes and as materials for occlusion coils. Other usable radiopaque materials are tantalum, gold and tungsten. Another option is to fill the wires or struts with a radiopaque material, as mentioned above. It is also possible to provide the implant, in particular the wires or struts, with a coating made of a radiopaque material, for example by applying a gold coating. This can have a thickness of, for example, 1 to 6 μm. The coating of radiopaque material does not have to be applied to the entire implant. Nevertheless, even when applying a radiopaque coating, it is considered useful to place one or more radiopaque markers on the implant, in particular at the distal end of the implant.

[0059] The implants provided according to the invention are particularly suitable for the treatment of intracranial bifurcation aneurysms, but their use in other types of aneurysms, such as aortic or peripheral aneurysms, is also conceivable, with the dimensions of the implant being appropriately adapted. For placing the implant in front of the bifurcation aneurysm, an insertion system such as that described in WO 2018 / 134097 can be used.

[0060] The present invention also relates to a method for manufacturing an implant as described above. For this purpose, at least three (most often exactly three) tubular parts are first manufactured individually. Each tubular part is made of struts connected to one another or interwoven wires. The tubular parts are each connected to one another at one end, and liquid flows from a first tubular part to a tubular part branching off from this first tubular part. When used in the intended application, the liquid referred to is blood. The connection of the tubular parts may be direct or indirect, in the case of an indirect connection a central connection element is placed between the tubular parts. In the case of a direct connection, the connection can be made, for example, by providing a fusion, preferably by welding, or by using a wire or thread.

[0061] In addition to the implant and the method for producing the implant, the present invention also relates to the use of the implant for treating arteriovenous malformations, in particular (bifurcation) aneurysms, and to the combination of the implant with an insertion system and possibly with a microcatheter. All statements made with respect to the implant itself apply in an analogous manner to the use of the implant, the method for producing the implant and the method for applying the implant, as well as to the combination of the implant with an insertion system.

[0062] The present invention is illustrated by way of example in the accompanying drawings, which show variations of preferred embodiments of the invention, but it should be noted that the invention itself is not limited thereto. So far as is technically expedient, the invention encompasses any combination of the technical features that are particularly described in the claims or the specification as being relevant to the invention.

[0063] The invention will become clearer with the aid of the following drawings. [Brief description of the drawings]

[0064] [Figure 1] FIG. 1 shows an implant according to a first embodiment. [Diagram 2] Variations of the implant according to the first embodiment [Diagram 3] Various views of the central connecting element [Figure 4] FIG. 2 shows an implant according to a second embodiment. [Diagram 5] FIG. 1 shows an implant according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] FIG. 1 shows an implant 1 according to a first embodiment. In the embodiment shown, three tubular parts 2, 3 are each connected at one end to a central connecting element 5, which itself is in the form of a Y-shaped structure with three arms 7 provided for connecting with the tubular parts 2, 3. The first tubular part 2 is placed in the parent vessel, the other distal tubular part 3 is placed in the branch vessel. The tubular parts 2, 3 are formed from interwoven wires 4, and the central connecting element 5 is a laser cut structure with individual struts 6. Each of the tubular parts 2, 3 is welded to the central connecting element 5 at one end.

[0066] FIG. 2 shows a variant of the first embodiment, in which a proximal tubular portion 2 is connected to two distal tubular portions 3 by a central connecting element 5. Here, the tubular portions 2, 3 are also made up of individual wires 4 braided together, and the central connecting element 5 is made up of laser-cut struts 6. The central connecting element 5 has a Y-shaped structure with three arms 7, each connected to the tubular portions 2, 3. However, in comparison with the variant shown in FIG. 1, the arms 7 of the Y-shaped structure have a greater overlap with the tubular portions 2, 3. In this case too, the connection is made by welding the wires 4 to the laser-cut connecting element 5.

[0067] Figure 3 shows various views of the central connecting element 5. As in Figures 1 and 2, Figure 3a is a side view; in Figure 3b, the central connecting element 5 is rotated by 90°. Figure 3c is a top view and Figure 3d is a side view. Here again, a structure consisting of struts 6 is observed, with the connecting element 5 forming a total of three individual arms 7.

[0068] 4 shows a second embodiment of the invention, in which an implant 1 comprises a first tubular portion 2 for placement in a parent vessel and two more distal tubular portions 3 for placement in branch vessels. In this case too, the tubular portions 2,3 are of braided construction consisting of individual wires 4; however, in contrast to the first embodiment, no central connecting element 5 is provided, instead the three tubular portions 2,3 are connected to each other by wires 8 threaded through the end meshes of the tubular portions 2,3.

[0069] A third embodiment of the invention is shown in Fig. 5 and is basically similar to the second embodiment, but in this embodiment no additional wires 8 are provided, instead the wires 8 for connecting the tubular parts 2,3 are the wires of the tubular parts 2,3 themselves. In this case the individual tubular parts 2,3 are thus intertwined with each other at the ends. Furthermore, it can be seen that the more distally located tubular part 3 has a smaller diameter than the proximally located tubular part 2, which is due to the fact that the inner diameter of the parent vessel is usually larger than that of the branch vessel.

Claims

1. 1. An implant for influencing blood flow in the region of an aneurysm located at a vascular bifurcation of a blood vessel, comprising: The implant (1) exists in an expanded state in which it is embedded in a blood vessel and in a contracted, elongated state in which it is movable through a blood vessel or a catheter; The implant (1) has at least three portions (2, 3) that are tubular at least in the expanded state, the walls of which are made of braided wires (4) or interconnected struts, at least two tubular portions (3) branching off from a first tubular portion (2); The at least three tubular portions (2, 3) are individually constructed and connected to each other at one end to ensure, in an expanded state, blood flow through the first tubular portion (2) to the tubular portion (3) branching off from the first tubular portion (2). An implant characterized by:

2. 2. The implant according to claim 1, characterized in that the at least three tubular parts (2, 3) meet at a central connecting element (5) by means of which the at least three tubular parts (2, 3) are connected to one another.

3. 3. An implant according to claim 2, characterized in that the connecting element (5) is made up of a number of struts (6) connected to one another.

4. 4. An implant according to claim 2 or 3, characterized in that the connecting element (5) has a Y-shaped structure, each arm (7) of which is attached to one of the tubular parts (2, 3).

5. The implant according to any one of claims 2 to 4, characterized in that the interconnected struts (6) of the connecting element (5) have the same length in the contracted, expanded state of the implant (1).

6. Implant according to any one of claims 2 to 5, characterized in that the tubular portions (2, 3) are attached to the connecting element (5) by means of wires and / or threads.

7. Implant according to any one of claims 2 to 5, characterized in that the tubular portions (2, 3) are attached to the connecting element (5) by fusion / material bonding.

8. An implant according to any one of claims 2 to 7, characterized in that the connecting element (5) is a laser cut structure.

9. An implant according to any one of claims 2 to 8, characterized in that the connecting element (5) comprises one or more membranes at least partially covering the connecting element (5), which membranes completely or partially prevent blood from entering or leaving the connecting element (5).

10. 2. The implant according to claim 1, characterized in that the at least three tubular parts (2, 3) are connected to each other by wires (8) and / or threads.

11. 11. An implant according to claim 10, characterized in that the wires (8) and / or threads have at least partially radiopaque properties.

12. 12. An implant according to claim 10 or 11, characterized in that the wire (8) forms part of or projects from the tubular portion (2, 3).

13. 2. The implant according to claim 1, characterized in that said at least three tubular portions (2, 3) are connected to each other by fusion / material bonding.

14. Implant according to any one of the preceding claims, characterized by one or more membranes at least partially covering said tubular portions (2, 3).

15. The implant according to any one of the preceding claims, characterized in that the at least two tubular portions (3) branching off from the first tubular portion (2) have, in the expanded state, a smaller diameter than the first tubular portion (2).

16. An implant according to any one of the preceding claims, characterized in that the walls of the tubular parts (2, 3) are made up of wires (4) braided together, at least some of the tubular parts (2, 3) being braided in such a way that at least one end of each tubular part (2, 3) has no free wire ends.

17. 17. An implant according to claim 16, characterized in that each of said tubular portions (2, 3) has an end with a free wire end and an end without a free wire end.

18. 18. An implant according to claim 17, characterized in that the tubular parts (2, 3) having ends without free wire ends meet or are centrally connected to one another at a central connecting element (5).

19. A method for manufacturing an implant (1) according to any one of claims 1 to 18, characterized in that the at least three tubular parts (2, 3) are first manufactured separately and then joined to each other at one end each.

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