Medical set for the treatment of aneurysms, manufacturing method and medical system for the treatment of aneurysms

Abstract

Medical set (2) for the treatment of aneurysms (4) with a main catheter (8), a covering device (12) which can be moved through the main catheter (8) to a treatment site (10) for covering an aneurysm (4), wherein the covering device (12) is connected or connectable to a transport wire (15) and comprises a self-expanding lattice structure (14) made of webs (16) which are integrally connected to one another and delimit inner cells (18) and edge cells (20), wherein the edge cells (20) form a closed edge cell ring (24) at a longitudinal end (22) of the lattice structure (14), which is connected to inner cells (18) only on one side, characterized in that the lattice structure (14) is provided with a cover (26) made of an electrospun fabric which has irregularly large pores (28), wherein the cover (26) has an area of 100,000 µm 2 at least 10 pores (28) having a size of at least 15 µm 2and wherein a plurality of inner cells (18) of the lattice structure (14) which are immediately adjacent in the circumferential direction of the lattice structure (14), in particular all inner cells (18) of an inner cell ring, are free of covering, wherein the cover-free inner cells (18) are cut free by means of a cutting tool by guiding the cutting tool along the webs of the inner cells (18) to be cut free.

Description

The invention relates to a medical kit for the treatment of aneurysms according to the preamble of claim 1.WO 2014 / 177634 A1 describes a highly flexible stent which has a compressible and expandable lattice structure, wherein the lattice structure is formed in one piece. The grid structure comprises closed cells, which are bounded by four grid elements each. The lattice structure has at least one cell ring comprising between three and six cells.It is also known from the practice of the applicant to provide stents having lattice structures formed from a single wire. The wire is self-braided to form a tubular braid. At the axial ends of the tubular braid, the wire is deflected, so that loops acting attraumatically are formed. The axial ends can be flared.The known medical device is particularly suitable for the treatment of aneurysms in small cerebral blood vessels. Such blood vessels have a very small cross-sectional diameter and are often highly convoluted. The known stent is designed to be highly flexible for this purpose, so that it is compressible to a very small cross-sectional diameter on the one hand and has a high bending flexibility, which enables the delivery into small cerebral blood vessels on the other hand.For the treatment of aneurysms in cerebral blood vessels, it is expedient to use stents which span over an aneurysm and shield it from the blood flow within the blood vessel. To enable this, it is known to provide stents with a cover which closes the cells of the stent and thus prevents blood flow into an aneurysm and perfusion of side branches of the blood vessel. Such a stent is known, for example, from US 2009 / 0069880 A1.A further supplementary or alternative treatment method of aneurysms is the implantation of so-called coils into the aneurysm, which leads there to blood coagulation. The resulting thrombus then prevents blood circulation in the aneurysm and thus the risk of rupture with subsequent bleeding.However, particularly in the case of wide-neck aneurysms, the coils tend to migrate into the blood stream during the implantation and thus cause closure of the main vessel lumen. In the "balloon assisted coiling" technique, catheters with "compliance balloons" are positioned in the vessel, especially at the height of the aneurysm neck. The contrast agent filled balloon closes the aneurysm neck during placement of the coils and forces the coils into a compact configuration within the aneurysm space. Because coils are plastically deformable, they then remain in their shape. They do not leave the aneurysm even when the balloon is removed. However, a problem exists here in particular due to the fact that the balloon closes the vessel. With a prolonged procedure (with large aneurysms, several coils are placed, the procedure can last several minutes), the blood flow is completely interrupted in time. Although bilateral vessels provide for the supply of downstream tissue, there is nevertheless the risk of underperfusion.Further, during the procedure, a catheter through which the coils are passed is "failed", i.e., clipped, to the side of the balloon. In the event of the potential need to change coil catheters (e.g., in the event of damage) during an incomplete procedure, the balloon should be deflated (deflated) to allow the catheter to be withdrawn. In this phase, a displacement of the coils, which are not yet completely and compactly located in the vessel, can occur. These can then lead to vessel closure.US 2018 / 0193026 A1 further discloses a stent having a lattice structure for the treatment of aneurysms. The stent is provided with a cover which covers the openings of the lattice structure and is intended to separate the aneurysm from the blood flow.Furthermore, US 2009 / 0069880 A1 discloses a stent graft for covering aneurysms. A guiding catheter is intended to properly align the graft of the stent graft with the aneurysm. For this purpose, the guide catheter can be guided through an opening in the graft material into the aneurysm.U.S. Pat. No. 9,005,695 B2 discloses a stent with a cover. The covering completely covers the stent. The covering is intended to serve to effect good ingrowth of the stent. In particular, the stent is intended to serve for the treatment of diseases of the esophagus.US 2005 / 0137677 A1 describes a stent with a cover. The cover may be coated with medicinally active substances.US 2009 / 0054966 A1 discloses a stent with a cover. The cover may have a different porosity in different sections.US 2003 / 0220682 A1 describes a stent for the treatment of tumors in the esophagus. The known esophageal stent has a cover which can be formed from an electrospun tissue in order to achieve the best possible growth of tissue cells over the stent. In this manner, the stent integrates into the endothelial tissue and permanently expands and stabilizes the diseased portion of the esophagus. For the expansion and stabilization function, the stent is equipped with a high radial force and an increased bending stiffness. The known stent is therefore not suitable for use in a blood vessel, in particular a cerebral blood vessel, which is highly wound.Against this background, it is an object of the invention to specify a medical set for the treatment of aneurysms, with the aid of which the risk of closing side branches of a blood vessel is at least reduced. A further object of the invention is to specify a production method for a medical set and a medical system.According to the invention, this object is achieved with respect to the medical set by the subject matter of claim 1, with respect to the method for producing a medical set by the subject matter of claim 8 and with respect to the medical system by the subject matter of claim 9.Preferred embodiments, developments and variants are the subject matter of the dependent claims.Specifically, the object is achieved by a medical set for the treatment of aneurysms, having a main catheter and having a covering device which can be moved through the main catheter to a treatment site. The treatment site can be understood here as a location along a vessel at which the aneurysm is formed. The covering device serves to cover the aneurysm. Furthermore, the covering can be a temporary covering of the aneurysm, for example only for a duration of the placement of an embolizing agent within the aneurysm. Particularly preferably, the covering is permanent, i.e. permanent, covering, for example in the form of a permanent implantation of the covering device into the vessel, especially in the form of a stent or a flow diverter.The covering device can be connected to a transport wire in a mechanically durable manner, i.e. in a non-detachable manner. If the covering device forms a permanent implant, for example a stent or a flow diverter, the connection to the transport wire can also be mechanically detachable. Furthermore, the covering device has a self-expandable lattice structure made of webs. Self-expandable can be understood here to mean that the lattice structure can transition from a compressed state in an expanded state without the action of external forces. For this purpose, the lattice structure preferably comprises a shape memory material or is formed from such a material.The webs of the lattice structure are integrally connected to one another and delimit inner cells and boundary cells, wherein the boundary cells form a closed boundary cell ring at a longitudinal end of the lattice structure, for example at a distal and / or proximal longitudinal end of the lattice structure. The rim cell ring is connected to the inner cells only on one side. The boundary cell ring can be understood here to mean a ring of cells adjacent in the circumferential direction, in particular boundary cells.Furthermore, the lattice structure is provided with a covering made of a fabric. The fabric has irregularly sized pores. At least one inner cell of the lattice structure is at least partially and in particular largely free of cover, i.e. it is not provided with the cover or with a part of the cover. Largely free of coverage can be understood here to mean that an in particular continuous surface of more than half of the total surface of the grid structure is free of coverage.The advantage here is that, on the one hand, the longitudinally axial blood flowability of the lattice structure ensures blood flow in the vessel, for example during the setting of a coil. On the other hand, a reliable and specifically location-specific covering of the aneurysm is ensured, but without lateral branches being covered by the covering. A further advantage is to be seen in the reduction of the overall area of the cover.Because of the lattice structure through which flow can take place axially, a flow of blood, in particular in the longitudinal direction through the blood vessel, is thus hardly impeded, but an inflow of the blood into a branching aneurysm is prevented by the cover or at least an influence of flow into the aneurysm is reduced. Particularly in the case of a permanent implantation of the covering device, this longitudinal axial flowability of the covering device has proven to be particularly suitable. A possible and undesirable closing of the vessel, as can occur, for example, in the aforementioned technique by means of the balloon, is thus at least reduced and preferably excluded. The at least one inner cell, which is free of covers, also makes it possible to supply the vascular tissue lying behind it.Such a configuration of the lattice structure also enables the use of the medical set as a stent or flow diverter which hardly obstructs a blood flow in the longitudinal direction and also, for example, to side vessels through the blood vessel, but prevents an inflow of the blood into a branching aneurysm through the cover or at least reduces the flow influence. A possible and undesirable closing of the vessel, as can occur, for example, in the aforementioned technique by means of the balloon, is thus at least reduced and preferably excluded. Furthermore, for example, side vessels located next to or in a vicinity of the aneurysm can continue to be flown through by blood.In particular in the case of fusiform aneurysms, i.e. aneurysms which extend over the entire circumference of a blood vessel, it is advantageous to use a structure which is specifically fine-pored for colonization of endothelial cells. A reconstruction of the missing vessel wall can thus be achieved. Specifically, the structure provided with a certain pore size, formed by the electrospun tissue, forms a framework for the colonization of endothelial cells, which can subsequently form a new, closed vessel wall. Fusiform aneurysms are understood here to mean aneurysms which extend over at least 50%, in particular over at least 75%, of the entire circumference or over the entire circumference of a blood vessel.According to the invention, the cover is formed from an electrospun fabric.In an electrospun web, pores are usually irregularly shaped. The production method does not in any case allow a pattern-like arrangement or design of pores to be produced. However, the pore sizes can be set on the basis of the process parameters at least to such an extent that it is ensured that at least some of the pores have a certain minimum size.For example, the process of electro-spinning can take place directly on the grid structure, so that a connection to the grid structure is simultaneously produced during the formation of the cover. The cover can be connected to the grid structure in a materially integral manner. For example, the cover can be connected to the grid structure by an adhesive connection. The adhesive connection can be produced by an adhesion promoter. The adhesion promoter can comprise polyurethane or consist thereof, for example.The electrospun web cover is also extremely thin and flexible, which helps the flexibility of the mesh structure. In particular, the cover hardly prevents the lattice structure from compressing, in contrast to previously known covers made of textile materials. Overall, the entire covering device can thus be compressed to a considerably smaller cross-sectional diameter and thus be guided via small catheters into particularly small blood vessels. This is relevant in particular for the treatment of aneurysms in cerebral blood vessels, for which purpose the invention is particularly suitable.The cover is preferably formed by a plastic material, in particular by a polymer, and preferably by polyurethane. Such materials are particularly light and can be readily produced in fine filaments by an electro-spinning process. The plastic material thus makes it possible on the one hand to produce a particularly thin and fine-pored covering. On the other hand, the plastic material already has a high flexibility in itself, so that a high compressibility of the medical set is achieved. Alternatively, the cover can also be formed by polyethylene and or fluoropolymers.Therefore, with the medical set according to the invention, treatments in blood vessels are also possible which cannot be achieved with previous medical devices having a lattice structure and a cover. Because of the high compressibility of the device according to the invention, very low delivery forces occur during delivery through a catheter. The material of the cover can also contribute to reducing the feed forces.In particular, the feed forces in the device with cover can be the same or smaller in comparison to the feed of the grid structure alone.Furthermore, the covering device, which is expediently arranged at the treatment site, i.e. at the height of the aneurysm, can prevent the coil from migrating out of the aneurysm during and after the coils have been set, such that the risk of vessel closure caused by the coils can likewise be at least greatly reduced and preferably excluded. Especially when the covering device is designed as a flow diverter, i.e. as a permanent implant, it is possible to dispense with inserting the coils into the aneurysm, since the covering preferably covers the aneurysm permanently, in particular in a fluid-dynamic manner.A further field of application of a partially covered device is fistulae, dissections and further malformations, for example arteriovenous malformations, in which the flow at targeted sites is to be slowed down or prevented, or the vascular wall reconstruction is promoted by a fine-mesh structure for promoting cell proliferation. In the open areas or in the open cells, the blood flow should be ensured unimpeded so that side branches are normally perfused. Moreover, foreign material is reduced to the most necessary to improve biocompatibility or reduce the possible thrombogenity.In order to ensure adequate flexibility of the cover, the latter is preferably formed from irregularly net-like arranged threads which have a thread thickness of between 0.1 μm and 3 μm, in particular between 0.2 μm and 2 μm, in particular between 0.5 μm and 1.5 μm, in particular between 0.8 μm and 1.2 μm.It is particularly preferred if the medical set is designed in the manner of a stent for the treatment of aneurysms in arterial, in particular neurovascular, blood vessels. The blood vessels can preferably have a cross-sectional diameter between 1.5 mm and 5 mm, in particular between 2 mm and 3 mm. The treatment of blood vessels having a cross-sectional diameter of 4 mm to 8 mm is also possible. Such cross-sectional diameters include carotid arteries, for example.In a further embodiment, all webs of the inner cell are each assigned to a further inner cell or boundary cell. Furthermore, the boundary cells each have at least two webs which are not assigned to any further inner cell or boundary cell. The webs thus form in this embodiment both a boundary for an inner cell and a boundary for their adjacent boundary cells.The grid structure can basically be formed as a one-piece grid structure. The wire mesh of the mesh structure may consist of a single wire which is redirected and fed back at the longitudinal ends of the mesh structure. The wire may be braided with itself to form the mesh structure. The mesh structure may also consist of a plurality of wires which are braided together. The plurality of wires may be redirected and recirculated at one axial longitudinal end, while the opposite axial longitudinal end may have wire ends that are open. It is also possible for the wires interwoven with one another to have open wire ends at both axial longitudinal ends. The wire may include an radiopaque core material and a shape memory alloy cladding material. In particular, it is provided that the volume ratio between the core material, preferably platinum, and the volume of the entire composite wire is between 20% and 40%, in particular between 25% and 35%. While a braided lattice structure is distinguished by a particularly high flexibility, in particular flexibility in bending, a single-piece lattice structure has a comparatively thin wall thickness, so that the lattice structure less strongly influences the blood flow within a blood vessel. The grating structure can also be laser-cut. Furthermore, the mesh structure may be formed as a closed structure for retraction into a catheter, with between preferably 6 and 12 cells along the perimeter of the mesh structure. The cells may have an asymmetric shape, i.e. the cells are substantially diamond-shaped, i.e. dragen-shaped, but may deviate from this shape due to varying web widths and lengths. However, the shape of the diamond or of the dragee remains substantially recognizable even in the event of a deviation.The grid structure preferably has a cross-sectional diameter between 2.5 mm and 8 mm, in particular between 4.5 mm and 6 mm.According to a preferred embodiment variant, the cover ends at the webs of the cover-free inner cells in such a way that the cover does not project into the at least one inner cell. In other words, the cover thus ends substantially flush at the webs, so that an edge of the cover preferably follows the contour of the webs.This ensures the freedom from coverage of the edge cells on the one hand and at the same time ensures reliable fastening, for example by means of the already mentioned adhesive connection, to the grid structure by the edge of the cover resting on the web.According to an alternative embodiment variant, the cover overlaps at least partially the webs of the cover-free inner cell in such a way that the cover partially protrudes into the at least one cover-free inner cell. In other words, according to this alternative embodiment, the cover does not just follow the contour of the webs and rather protrudes over at least 20%, in particular over at least 30%, in particular over at least 40%, in particular over at least 50%, of the surface of the at least one inner cell into the latter.In both design variants, however, the cover remains stable. The cover is preferably stable over a long period of time or in such a way that the mass of the cover is reduced by at most 5%, in particular by at most 3%, in particular by at most 1%, in the case of contact with blood or a physiological replacement liquid, in particular with a sodium chloride solution or a Ringer lactate solution, when a flow of in particular 100 ml to 400 ml per minute passes through it, over a period of at least four hours, in particular at least 30 days. This ensures that the effect of the coating exists over a sufficiently long period of time.It is particularly preferred if the cover is sufficiently stable or stable over a long term that the mass of the cover is completely retained during contact with blood or a physiological replacement liquid, in particular with a sodium chloride solution or a Ringer lactate solution, over a period of at least four hours, in particular at least 30 days. Such a period of time allows, for example, the medical device to be coated with an endothelial cell layer, so that thrombus formation is naturally prevented. The antithrombogenic coating thus bridges the period of time until the medical device naturally heals or encapsulates it in a neointima layer, in particular of endothelial cells, which forms around the network structural elements.The use of a physiological replacement liquid for testing the long-term stability of the covering enables an objective comparison. Furthermore, the use of the replacement fluid, which is preferably similar to human blood, achieves the possibility of ascertaining objective experiences therefrom, which suggest the behavior of the covering in the implanted state when the covering is exposed to the human blood flow. Therefore, a 0.9 percent sodium chloride solution or a Ringer lactate solution is preferably used as replacement liquids. Such replacement fluids are isotonic and are well suited as indicators of the behaviour of the covering in the implanted state.According to the invention, a plurality of inner cells, in particular all inner cells, of an inner cell ring, which are directly adjacent in the circumferential direction of the grid structure are free of coverage. This ensures that adjacent side vessels and / or cells along the vessel can still be supplied with blood and thus with nutrients, while the aneurysm is reliably covered by the cover. Furthermore, this allows an individual covering effect / function of lattice structures with regard to an arrangement pattern of aneurysms along the vessel, so that, for example, only at the treatment sites at which an aneurysm is located are the inner cells provided with the covering and the remaining inner cells of the inner cell ring are free of covering.In addition, a plurality of inner cells directly adjacent in the longitudinal direction of the grid structure can be free of coverage. This advantageously optimizes the aforementioned possibility of the individual covering effect / function of the covering device.According to one embodiment, the cover extends only partially, in particular to the extent of at most 50%, in particular to the extent of at most 40%, in particular to the extent of at most 30%, in particular to the extent of at most 20%, over the circumference of the lattice structure. The cover thus preferably extends only over the treatment site, i.e. for example over an opening of the aneurysm. This further development ensures that the aneurysm is completely decoupled in fluid dynamic manner when the grid structure is used as a flow diverter. On the other hand, this ensures that cells and / or side vessels located in particular at the level of the aneurysm can still be supplied with blood and thus with nutrients due to the lack of coverage.According to the invention, the covering has at least 10 pores on an area of 100,000 μm 2 which have a size of at least 15 μm 2. During the production of the cover, the minimum size of the pores can be adjusted in particular by the process duration of the electro-spinning. This combination of a certain minimum number of pores and a minimum size of these pores has been shown in practice to be particularly favourable for an adequate blood permeability of the covering with simultaneously good covering action.An independent aspect of the invention relates to a method for producing a medical set, wherein this is preferably the medical set already described above. The method comprises the following steps.First, the grating structure is provided. The cover is then applied to all inner cells, specifically by an electro-spinning process.Subsequently, at least one inner cell is cut free by means of a cutting tool, wherein the cutting tool is guided along the webs of the inner cell to be cut free. The inner cell is thereby completely free of cover.The cutting tool can be a mechanical cutting tool, for example a scalpel. The cutting tool is preferably a laser cutting tool, so that the cover is removed along the webs by means of a laser beam, so that the inner cell is cut free. Alternatively, the cutting device may also be a device that ensures freedom from coverage of the at least one inner cell by etching.Furthermore, it can additionally be provided that the edges of the cover are post-machined on the cover-free inner cells. This can preferably be carried out thermally, for example by means of a soldering iron, in that in a first step, the edges are roughly machined at a first temperature and subsequently, the edges are finely machined at a temperature which is lower with respect to the first temperature.A further subordinate aspect of the invention relates to a medical system with a medical set, wherein this is in particular the medical set already described above, so that the medical set has a main catheter and a covering device for covering an aneurysm, which covering device can be moved through the main catheter to a treatment site.The covering device is connected or connectable to a transport wire. Furthermore, the covering device has a self-expanding grid structure which comprises webs which are connected integrally to one another and delimit inner cells and boundary cells. The boundary cells form a closed boundary cell ring along the circumference of the lattice structure at a longitudinal end of the lattice structure. The edge cell ring is connected to inner cells only on one side, i.e. on the side oriented in the direction of the inner cells. Furthermore, the medical system has at least one embolizing agent for placement in the aneurysm. The embolizing agent is preferably formed by a plastically deformable wire, in particular by a coil or by a liquid. Such embodiments of the embolizing agent have proven particularly suitable with regard to treatment of aneurysms.In the case that the covering device is detachably, i.e. reversibly, connected to the transport wire, the covering device particularly preferably serves as a flow diverter for a permanent implantation at the treatment site within the blood vessel. The reversible arrangement of the covering device on the transport wire is realized, for example, by means of a releasable mechanical locking mechanism. Furthermore, in this embodiment, the covering device designed as a flow diverter has open longitudinal ends in the implanted and expanded state, i.e. is designed to be open on both sides. The covering device is thus substantially cylindrical, i.e. tubular, in design, so that blood flow through the blood vessel is still possible. Thus, it is possible to place the embolizing agent-if necessary-both during the implantation of the covering device and at a later time following the implantation of the covering device.In one embodiment and preferably, the medical system further comprises an auxiliary catheter for supplying the embolizing agent into the aneurysm, wherein the auxiliary catheter is independent of the main catheter and / or is relatively movable with respect to the main catheter.The advantages and preferred embodiments listed with regard to the medical set are to be transferred analogously to the method and to the medical set and vice versa. All dimensional specifications listed in relation to the medical set and in relation to the medical system apply to an expanded state of the lattice structure, unless otherwise stated.Exemplary embodiments of the invention are explained in more detail below with reference to the attached schematic drawings. These are shown in a partially greatly simplified illustration: FIG. 1 shows a side view of an embodiment of the medical kit according to the invention, FIG. 2 shows a close-up view of a preferred embodiment of a covering device of a medical set according to the invention according to a preferred embodiment, FIG. 3 shows a scanning electron microscope photograph of a cover of a cover device of a medical kit according to the invention according to a preferred embodiment, FIG. 4 shows a side view of an embodiment of the medical system according to the invention, during a temporary implantation of the covering device at a treatment site, and FIG. 5 shows a side view of a preferred embodiment of the medical system according to the invention, during a permanent implantation of the covering device at a treatment site.In the figures, parts having the same function are always represented by the same reference numerals.The medical set 2 schematically shown in FIG. 1 serves for the treatment of aneurysms 4 and is shown in FIG. 1 in a state arranged within a vessel 6.The medical set 2 has a main catheter 8 and a covering device 12 which can be moved through the main catheter 8 to a treatment site 10. The treatment site 10 is preferably the site along the vessel 6 at which the aneurysm 4 is formed. The covering device 12 serves for temporarily or permanently covering the aneurysm 4, wherein the covering device 12 comprises a self-expandable lattice structure 14 made of webs 16 (cf. FIG. 2 ). The lattice structure 14 is preferably made of a shape memory material with regard to its self-expandability.Furthermore, the covering device 12 is permanently or releasably mechanically connected to a transport wire 15 which is displaceable within the main catheter 8. By means of this transport wire 15, the lattice structure 14 and thus the covering device 12 can be pushed and retracted through the main catheter 8 in an unexpanded stateIn the expanded state, the lattice structure 14 can be flown through in a longitudinal axial manner, i.e. in and counter to a flow direction F.The lattice structure 14 is in particular arranged within the vessel 6 in such a way that the cover 26 is placed at a height with an opening 30 of the aneurysm 4 so that the latter is covered by the cover 26, wherein at the same time a blood flow through the vessel 6 is not stopped. The cover 26 is thus formed in the exemplary embodiment according to FIG. 1 substantially tube-like, in particular in the manner of a hollow cylinder.The cover 26 is preferably porous with large pores 28 (cf. FIG. 3 ) and is designed to be blood-permeable, so that a supply of nutrients to the cells covered by the cover 26 is still ensured. Alternatively, however, the cover 26 can also be porous and impermeable to blood.The cover 26 serves here, in particular when placing an embolizing agent 36 (cf. FIG. 4 ) within the aneurysm 4, for the embolizing agent 40 not to be able to escape from the aneurysm 4 after the placement until the blood within the aneurysm 4 has been coagulated by the embolizing agent 36 and thus the aneurysm 4 is reliably closed.Particularly preferably, the cover 26 is formed as an electrospun cover 26.As can be seen easily in FIG. 1, x-ray markers 32 are also provided in the medical set 2 and especially in the grating structure 14. The X-ray markers 32 are preferably arranged at cell tips of boundary cells 20 (cf. FIG. 2 ) of the lattice structure 14. Specifically, the X-ray markers 56 can be formed as X-ray-visible sleeves, for example made of platinum or gold, which are crimped onto the cell tips of the boundary cells 20.Referring now to Fig. 2, there is shown a close up view of a preferred embodiment of the cover assembly 12 of the present invention. The webs 16 are connected to one another in one piece, i.e. monolithically, and delimit inner cells 18 and boundary cells 20. These cells enclosed on all sides are referred to as closed cells. The boundary cells 20 form, at a longitudinal end 22 of the lattice structure 14, a closed boundary cell ring 24 (three boundary cells 20 of the boundary cell ring 24 are shown encircled) in the circumferential direction, which is connected to inner cells 18 only on one side.Furthermore, the lattice structure 14 is provided with the covering 26 made of a fabric which has irregularly sized pores 28 (cf. FIG. 3 ). At least one inner cell 18, three inner cells 18 in FIG. 1 (in the image plane at the right edge of the grid structure 14), are formed without any cover.The design of the cover 26 is clearly recognizable in the scanning electron microscope photograph according to FIG. 3. It can be seen therein that the cover 26 has a plurality of irregularly sized pores 28 which are each bounded by filaments 34. The electro-spinning process forms a plurality of filaments 34 which are aligned irregularly with respect to one another. The pores 28 are formed in this case. It can also be seen in FIG. 3 that the pores 28 have a comparatively small pore size, wherein some pores 28, however, are sufficiently large in order to ensure blood permeability, for example. Specifically, four pores 28 having a size of more than 30 μm 2 are graphically emphasized in FIG. 3. The density of the pores 28 having a size of more than 30 μm 2 reveals that the covering has at least 10 such pores 28 on an area of 100,000 μm 2.In FIG. 3, it can also be seen in each case that the threads 34 of the cover 26 cross one another multiple times. However, a special feature of the electro-spinning method is that the cover 26 has points at which only, i.e. no more than, two threads 34 cross over one another. It can be seen from this that the cover 26 overall has a very thin wall thickness and is therefore highly flexible.The high flexibility of the cover 26 in combination with the high flexibility of the lattice structure 14 results in a cover device 12 being able to be provided, which can be introduced into a (blood) vessel 6 through very small delivery catheters. In particular, delivery catheters can be used which have a size of 6 French, in particular at most 5 French, in particular at most 4 French, in particular at most 3 French, in particular at most 2 French. Specifically, the covering device according to the exemplary embodiments described here can be used in catheters which have an inner diameter of at most 1.6 mm, in particular at most 1.0 mm, in particular at most 0.7 mm, in particular at most 0.4 mm.In particularly preferred variants, the layer thickness of the cover 26 is at most 10 μm, in particular at most 8 μm, in particular at most 6 μm, in particular at most 4 μm. In this case, at most 4, in particular at most 3, in particular at most 2, threads 34 cross over one another. In general, cross-over points are provided within the electrospun structure of the cover 26, in which only 2 threads 34 cross over one another. The grid structure 10 preferably has a cross-sectional diameter between 2.5 mm and 8 mm, in particular between 4.5 mm and 6 mm.FIG. 4 shows a schematically illustrated exemplary embodiment of a medical system according to the invention during a temporary implantation of the covering device 12 at a treatment site 10.The medical system has the medical set 2 already mentioned above with the main catheter 8 and the covering device 12 which has the lattice structure 14 and the cover 26. The design of the cover 26 corresponds to the embodiment already mentioned above according to FIG. 1.Furthermore, the medical system has an embolizing agent 36, which is formed, for example, by a plastically deformable wire 38 or by a liquid. The embolizing agent 36 is placed inside the aneurysm 4 by means of an auxiliary catheter 40, which is also part of the medical system.For placing the embolizing agent 36, the auxiliary catheter 40 according to the illustrated embodiment of the medical system is arranged substantially parallel, i.e. next to the medical set 2 within the vessel 6. In this case, the additional catheter 40 and specifically a tip of the additional catheter 40 is then "pushed" into the aneurysm 4 between a vessel wall and the cover 26, in order to place the embolizing agent 36 there in the form of the plastically deformable wire 38 (also referred to as "coil"). During this time and during a continuous implantation, the cover 26 also subsequently prevents the embolizing agent 36 from coming out of the aneurysm 4, for example due to the blood flow.FIG. 5 shows a schematically illustrated exemplary embodiment of a medical system according to the invention during a permanent implantation of the covering device 12 at a treatment site 10.With regard to the structural features, the medical set and the covering device 12 substantially correspond to the medical set already described above in FIG. 4. The covering device 12 is shown in FIG. 5 in a state already implanted and expanded in the vessel 6. That is, the covering device 12 has already been moved by means of the transport wire 15 to the treatment site 10 and detached from the transport wire 15 there.However, the covering device 12 according to FIG. 5 has in each case open longitudinal ends and is therefore substantially cylindrical, that is to say tubular, in order not to influence a blood flow through the vessel. The covering device 12 in the exemplary embodiment according to FIG. 5 thus serves as a flow diverter.List of reference characters2 Medical set 4 aneurysm 6 vessel 8 main catheter 10 treatment site 12 covering device 14 lattice structure 15 transport wire 16 web 18 inner cell 20 boundary cell 22 longitudinal end 24 boundary cell ring 26 cover 28 pore 30 opening of aneurysm 32 X-ray marker 34 thread 36 embolizing agent 38 wire 40 additional catheter F flow direction

Claims

Medical set (2) for the treatment of aneurysms (4) having a main catheter (8), a covering device (12), which can be moved through the main catheter (8) to a treatment site (10), for covering an aneurysm (4), wherein the covering device (12) is connected or can be connected to a transport wire (15) and comprises a self-expandable lattice structure (14) made of webs (16) which are connected integrally to one another and delimit inner cells (18) and boundary cells (20), wherein the boundary cells (20) form, at a longitudinal end (22) of the lattice structure (14), a closed boundary cell ring (24) which is connected only on one side to inner cells (18), characterized in that the lattice structure (14) is provided with a covering (26) made of an electrospun tissue which has irregularly sized pores (28), wherein the cover (26) comprises at least 10 pores (28) on an area of 100,000 μm 2 which have a size of at least 15 μm 2 and wherein a plurality of inner cells (18), in particular all inner cells (18) of an inner cell ring, directly adjacent in the circumferential direction of the grid structure (14) are cover-free of the grid structure (14), wherein the cover-free inner cells (18) are cut free by means of a cutting tool by guiding the cutting tool along the webs of the inner cells (18) to be cut free.Medical set (2) according to claim 1, characterised in that the covering device (12) can be connected reversibly to the transport wire (15) and, in the expanded state, is open on both sides and can be flown through by blood.Medical set (2) according to claim 1 or 2, characterised in that all webs (16) of the inner cells (18) are each assigned to a further inner cell (18) or edge cell (20) and the edge cells (20) each have at least two webs (16) which are not assigned to a further inner cell (18) or edge cell (20).Medical set (2) according to one of the preceding claims, characterized in that the cover (26) ends at the webs (16) of the cover-free inner cell (18) in such a way that the cover (26) does not project into the cover-free inner cell (18).Medical set (2) according to one of claims 1 to 3, characterised in that the cover (26) at least partially overlaps the webs (16) of the cover-free inner cell (18), so that the cover (26) partially protrudes into the cover-free inner cell (18).Medical set (2) according to one of the preceding claims, characterized in that a plurality of inner cells (18) which are directly adjacent in the longitudinal direction of the lattice structure (14) are free of coverage.Medical set (2) according to one of the preceding claims, characterized in that the cover (26) has a layer thickness which is at most 10 μm, in particular at most 8 μm, in particular at most 6 μm, in particular at most 4 μm.Method for producing a medical kit (2) according to one of the preceding claims, wherein the method comprises the following steps: a. providing the lattice structure (14); b. applying the cover (26) to all inner cells (18) by an electro-spinning process; c. cutting free at least one inner cell (18) by means of a cutting tool, wherein the cutting tool is guided along the webs (16) of the inner cell (18) to be cut free, so that the inner cell (18) becomes free of cover.Medical system with a medical set (2) according to one of claims 1 to 7, wherein the medical set (2) has a main catheter (8) and a covering device (12), which can be moved through the main catheter (8) to a treatment site (10), for covering an aneurysm (4), wherein the covering device (12) is connected or can be connected to a transport wire (15) and comprises a self-expandable lattice structure (14) made of webs (16), which are connected integrally to one another and delimit inner cells (18) and boundary cells (20), wherein the boundary cells (20) at a longitudinal end (22) of the lattice structure (14) form a closed boundary cell ring (24), which is connected only on one side to inner cells (18), and having at least one embolization means (36) for placement in the aneurysm (4).Medical system according to claim 9, characterised in that the covering device (12) can be detachably connected to the transport wire (15) for a permanent implantation of the covering device (12) at the treatment site (10), wherein the covering device (12) has open longitudinal ends in the expanded state.Medical system according to claim 9, characterised in that the covering device (12) is non-detachably connected to the transport wire (15) for temporary implantation of the covering device (12) at the treatment site (10).Medical system according to one of Claims 9 to 11, characterized in that an additional catheter (40) is furthermore provided for supplying the embolizing agent (36) into the aneurysm, wherein the additional catheter (40) is movable independently of the main catheter (8) and / or relative to the main catheter (8).

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