DE102019121559B4 - Medical device for insertion into a hollow body organ and method for producing a medical device - Google Patents

Abstract

Medical device (2) for the treatment of aneurysms in cerebral blood vessels, comprising a compressible and expandable lattice structure (10) made of lattice elements (11, 12, 13, 14) forming cells (15), wherein the lattice structure (10) comprises, at least in sections, a cover (16) made of an electrospun fabric, which, in an implanted state of the lattice structure (10), reduces the blood flow through the hollow body organ by means of the lattice structure (10) in the region of the cover (16), wherein the lattice structure (10) is formed with a taper (23) in a central region (20), and wherein at least the central region (20) comprises the cover (16), wherein the cover (16) has a porosity with pores having a size of at most 750 µm ² and comprises at least 15 pores having a ^size of at least 30 µm ² , and wherein the cover (16) has a blood-permeable and a blood-impermeable area.

Description

The invention relates to a medical device for insertion into a hollow body organ according to the preamble of patent claim 1. Furthermore, the invention relates to a manufacturing method.

WO 2014/177634 A1 describes a highly flexible stent comprising a compressible and expandable lattice structure, wherein the lattice structure is formed as a single piece. The lattice structure comprises closed cells, each defined by four lattice elements. The lattice structure has at least one cell ring comprising between three and six cells.

The applicant's practice also includes stents with lattice structures made of a single wire. The wire is interwoven to form a tubular mesh. At the axial ends of the tubular mesh, the wire is deflected to form atraumatic loops. The axial ends can be flared out in a funnel shape.

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 tortuous. The known stent is designed to be highly flexible, allowing it to be compressed to a very small cross-sectional diameter while also exhibiting high bending flexibility, allowing it to be delivered into small cerebral blood vessels.

To treat aneurysms in cerebral blood vessels, it is advisable to use stents that span the aneurysm and shield it from blood flow within the blood vessel. To achieve this, it is known to provide stents with a covering that seals the stent cells and thus prevents blood flow into the aneurysm. Such coverings are often made of textile materials. In combination with the stent structure, however, this results in a relatively thick stent wall, which in turn limits the compressibility of the stent. The covering thus limits compression to a small cross-sectional diameter, which in turn hinders the insertion of the stent into small cerebral blood vessels. The invention, which originates from the applicant, EP 2 946 750 B1 attempts to solve the compressibility of a stent with a textile cover by providing fiber strands of the textile material from loosely arranged individual filaments.

Textile-like structures suitable for covering aneurysms are known from the state of the art. In particular, EP 2 546 394 A1 Such a covering, a so-called graft, features an electrospun structure. To achieve particularly low porosity, several layers of this electrospun structure are superimposed. However, this results in a high wall thickness, which is a hindrance when delivering it into small, highly curved blood vessels.

Out of WO 02/49536 A2 An electrospun structure is also known that features two layers of electrospun fabric, each with different porosities. Here, too, the wall thickness is relatively large, thus limiting the compressibility of the electrospun structure.

EP 2 678 446 B1 deals with a stent for neurovascular applications covered with a nonwoven fabric. The nonwoven fabric is produced by electrospinning and comprises several layers, with an inner layer impermeable to liquids and an outer layer sponge-like. The nonwoven fabric thus forms a membrane with very low fluid permeability and, due to the sponge-like layer, has an increased wall thickness, which impairs the compressibility of the stent.

US 9 005 695 B2 This study involves a stent with an electrospun cover with varying porosity in the radial direction. The electrospun cover is designed to attract tissue cells, allowing the stent to grow into the tissue.

US 2008/0036113 A1 describes a prosthetic heart valve that is at least partially covered by a membrane that opens to allow blood flow through the prosthetic heart valve.

US 2003/0065355 A1 discloses a thrombus filter that is essentially funnel-shaped and has a membrane designed to span the cross-sectional area of a blood vessel. The membrane is formed by electrospinning and additionally has pores designed to allow blood flow. It is described that blood should pass through the thrombus filter, while larger components, particularly thrombi, should be filtered out.

Out of WO 2014/007631 A1 further discloses an implant for a tissue replacement, wherein the implant comprises an electrospun matrix tissue The matrix tissue is intended to promote the settlement of endothelial cells.

The invention is based on the object of providing a medical device for insertion into a hollow body organ that can be compressed to a very small size and simultaneously provides effective shielding of an aneurysm by reducing blood flow through a hollow body organ. Furthermore, the object of the invention is to provide a manufacturing method.

According to the invention, this object is achieved with regard to the medical device by the subject matter of patent claim 1 and with regard to the manufacturing method by the subject matter of patent claim 14.

Specifically, the problem is solved by a medical device for treating aneurysms in cerebral blood vessels with a compressible and expandable lattice structure composed of lattice elements. The lattice elements are integrally connected to one another and form cells. In the following, the terms "hollow body organ" and "blood) vessel" are used interchangeably.

According to the invention, the lattice structure comprises, at least in sections, a cover made of an electrospun fabric which, in an implanted state of the lattice structure, reduces the blood flow through the hollow body organ by means of the lattice structure in the region of the cover.

The grid structure is formed with a taper in a central region, wherein at least the central region comprises the cover.

The cover has a porosity with pores having a size of no more than 750 ^µm² and comprises at least 15 pores with a size of at least 30 ^µm² over an area of 100,000 ^µm² . The cover has a blood-permeable and a blood-impermeable area.

In electrospun fabrics, pores are typically irregularly shaped. The manufacturing process certainly doesn't allow for a patterned arrangement or design of pores. However, the pore sizes can be adjusted using the process parameters to ensure that at least some of the pores have a certain minimum size.

For example, the electrospinning process can be carried out directly on the grid structure, so that a connection to the grid structure is created at the same time as the cover is formed.

The invention has the advantage of combining a highly flexible lattice structure as a support structure with a cover that is particularly thin and flexible due to its manufacturing process. As a result, the medical device is highly compressible and can be easily inserted into very small blood vessels. The high flexibility of the support structure and the lattice structure is due to the very small pore size of the pores in the cover. The small pores result in a thin wall thickness of the cover and thus enable the lattice structure to be compressed to a very small cross-sectional diameter.

The medical device according to the invention therefore also enables treatments in blood vessels that cannot be achieved with previous medical devices that have a lattice structure and a cover. This is particularly relevant for the treatment of aneurysms in cerebral blood vessels, for which the invention is particularly suitable. In particular, it enables a reduction in blood flow through such blood vessels, for example, to treat an aneurysm that has developed there.

Due to 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 delivery forces. In particular, the delivery forces for the device with the cover can be the same as or lower than for delivery of the grid structure alone.

The highly flexible grid structure as a support structure has the further advantage that the grid structure can be retracted into a catheter, e.g. after temporary placement within the blood vessel, since the cover means that no grid elements protrude that could catch on a catheter tip.

Preferred embodiments of the invention are specified in the subclaims.

In a preferred embodiment, the cover covers at least 70%, in particular at least 80%, in particular at least 90% of the cross-sectional area of the hollow body organ, in particular the blood vessel. This achieves a reliable reduction in blood flow through the hollow body organ. This is particularly nearly achieved when the cover covers at least 90% of the cross-sectional area of the hollow body organ.

To further improve the reduction of blood flow through the cover in the expanded state of the lattice structure, in a further preferred embodiment, at least 60%, in particular at least 70%, in particular at least 80% of the cover's surface is formed by pores. These preferably have an inscribed circle diameter of at least 30 µm. The inscribed circle diameter is the diameter of the largest possible circle that can be inscribed in the pore. In other words, the inscribed circle diameter of the pore corresponds to the outer diameter of a cylinder that can just barely be pushed through the pore.

The minimum pore size can be adjusted during cover production and has a significant influence on the compressible cross-sectional diameter and the bending flexibility of the lattice structure. A cover made of an electrospun fabric is extremely thin and flexible, thus supporting the flexibility of the lattice structure. By forming very small pores, the cover hardly prevents the lattice structure from compressing, unlike previously known covers made of other textile materials. Overall, the entire medical device according to the invention can therefore be compressed to a significantly smaller cross-sectional diameter and thus guided into particularly small blood vessels via small catheters.

According to the invention, the pores have a size of at most 750 µm ² , in particular of at most 500 µm ² , in particular of at most 300 µm ² . This ensures that the permeability of the cover is not too great, so that a medically sensible reduction of the blood flow through the hollow body organ and thus a sensible shielding of the aneurysm from the blood flow in the vessel is achieved.

It is further provided according to the invention that the cover comprises at least 15 pores, in particular at least 20 pores, in particular at least 25 pores, on an area of 100,000 µm ² , which have a size of at least 30 µm ² , in particular at least 50 µm ² , in particular at least 70 µm ² , in particular at least 90 µm ² .

The flexibility of the cover or the grid structure is increased by the cover preferably being formed from irregularly arranged net-like threads which have a thread thickness between 1 µm and 2 µm.

The cover is preferably arranged on an outer side and/or inner side of the grid structure. If the cover is arranged on an outer side of the grid structure, the grid structure forms a support structure that exerts sufficient radial force to fix the cover against a vessel wall. The support structure thus supports the outer cover. Alternatively, the cover can also be arranged on an inner side of the grid structure. In particular, it is possible for the grid structure to be embedded between two covers, each formed by an electrospun fabric. The grid elements of the grid structure can thus be completely encased by the electrospun fabric. Specifically, it can be provided that the electrospun fabric of a cover on the inner side of the grid structure extends through the cells of the grid structure and is connected to the electrospun fabric of a cover on the outer side of the grid structure. The grid elements that delimit the cells are thus encased on all sides by electrospun fabric.

In a preferred embodiment, the cover is irreversibly connected to the grid structure, in particular by a material bond. The irreversible connection between the cover and the grid structure prevents the cover from detaching from the grid structure, for example, when the medical device is inserted through a catheter.

The cover is preferably made of a plastic material, in particular a polyurethane. Such materials are particularly lightweight and can be easily produced in fine threads using an electrospinning process. On the one hand, the plastic material enables the production of a particularly thin and fine-pored cover. On the other hand, the plastic material is inherently highly flexible, thus achieving a high compressibility of the medical device. Alternatively, the cover can also be made of polyethylene, fluoropolymers, or thermoplastic polyurethanes based on polycarbonate, for example. Furthermore, it can be additionally provided, for example, that fillers, such as anti-thrombogenic substances, are embedded in the aforementioned materials of the cover following the electrospinning process.

According to the invention, the cover has a blood-permeable and a blood-impermeable area. This has the advantage that the medical device, when expanded, allows both a nutrient supply to the aneurysm and, at the same time, a good shielding of the aneurysm. Furthermore, a nutrient supply to branching blood vessels and adjacent vessel walls is also possible. The blood permeability of the cover is useful in order to to supply the cells of the aneurysm wall with nutrients, thereby preventing cell degeneration and a potentially resulting rupture of the aneurysm. Specifically, the blood-impermeable region is preferably formed by the cover. The blood-permeable region is preferably formed by the portion of the surface of the lattice structure that is not covered by the cover. Alternatively or additionally, the blood-permeable region can be formed by the portion of the cover that is not formed from the aforementioned pores. For example, the blood-impermeable region can thus be formed by the remaining 40% of the surface of the cover if 60% of the surface of the cover is formed by pores, as already explained above.

In a preferred embodiment, the cover has radiopaque markers, in particular radiopaque sleeves, e.g., made of patin or gold, at least at its longitudinal ends. This facilitates the positioning of the medical device under X-ray control. Since the cover is irreversibly connected to the grid structure, in particular by a material bond, the relative position between the cover and the grid structure remains constant. Thus, no additional X-ray markers, which would reveal a relative displacement between the cover and the grid structure, are required. Overall, the number of X-ray markers, e.g., X-ray marker sleeves, can be reduced, which in turn has a positive effect on the compressibility of the medical device.

In order to increase the stability of the grid structure, in a preferred embodiment the grid elements are coated with an adhesion promoter, in particular polyurethane, wherein the adhesion promoter preferably forms the material connection of the cover with the grid structure.

The mesh elements preferably form webs that are integrally connected to one another by web connectors, or interwoven wires. A one-piece mesh structure has a comparatively thin wall thickness, so that blood flow within a blood vessel is less affected. A braided mesh structure, on the other hand, is characterized by particularly high flexibility, particularly bending flexibility. Furthermore, mesh structures formed from a wire mesh are more cost-effective to manufacture than mesh structures made from a single piece.

In a preferred embodiment of the invention, the lattice structure forms, at least in sections, a cylindrical and/or funnel-shaped hollow body. A substantially cylindrical hollow body enables the lattice structure to adhere to the vessel walls of a blood vessel. A funnel-shaped hollow body can be used, for example, to collect thrombi within a blood vessel or to treat vessels with varying diameters. In a funnel-shaped hollow body, the axial ends of the lattice structure can be radially widened (flaring), in particular funnel-shaped, or radially tapered, in particular conical. The flaring angle can preferably be between 50° and 70°, in particular between 55° and 65°. Funnel-shaped can be understood to mean both a rotationally symmetrical cross-sectional contour and, alternatively, a non-rotationally symmetrical cross-sectional contour.

In a preferred embodiment, the medical device is arranged in a compressed state on or at a transport wire such that the medical device is axially displaceable within a delivery tube (also referred to as an introduction aid), wherein the delivery tube expediently has an internal diameter of a maximum of 5 µm. The arrangement of the medical device on or at the transport wire is reversible or irreversible. In one embodiment, this enables the medical device to be used as a permanent implant, in particular in the form of a permanently implantable stent, when the medical device is reversibly arranged on the transport wire. For this purpose, after the medical device has been placed within the blood vessel, the reversible arrangement with the transport wire is released and the wire is removed from the vessel. In an alternative embodiment, the medical device can be used as a thrombectomy device in an irreversible arrangement on or at the transport wire, wherein the thrombectomy device is preferably only temporarily released into a blood vessel and is removed from the vessel again after treatment with the transport wire.

Preferably, the medical device is precisely compatible with a 2Fr catheter. Precise compatibility means that relative movement between the medical device and such a 2Fr catheter in the axial direction is possible. For this purpose, a minimal gap or play is provided between the outer diameter of the medical device and the inner diameter of the catheter in use. In other words, the outer diameter of the medical device is, for example, 0.05 mm to 0.1 mm smaller than the inner diameter of the catheter in use. The advantage The advantage of the precise compatibility with a 2Fr catheter is that the transport wire and catheter body form a very compact unit during use, thus virtually eliminating relative movement between the transport wire and the catheter body in the radial direction, i.e., perpendicular to the guide wire. This, in turn, allows the catheter to be navigated precisely and guided with minimal resistance.

• Bereitstellen einer komprimierbaren und expandierbaren Gitterstruktur aus Gitterelementen, die geschlossene Zellen der Gitterstruktur begrenzen;
• Beschichten der Gitterstruktur mit einem Haftvermittler, insbesondere aus Polyurethan; und
• Aufbringen einer Abdeckung auf die Gitterstruktur durch einen Elektrospinnprozess.

A secondary aspect of the invention relates to a method for producing a medical device for insertion into a hollow body organ. In particular, the application discloses and claims a method for producing a medical device having the aforementioned features. In general, the method according to the invention comprises the following steps:

• Providing a compressible and expandable lattice structure of lattice elements that define closed cells of the lattice structure;
• Coating the grid structure with an adhesion promoter, in particular polyurethane; and
• Applying a cover to the grid structure through an electrospinning process.

In the method according to the invention, the cover is manufactured directly onto the grid structure. To achieve a strong bond between the grid structure and the cover, an adhesion promoter is used, preferably made of a biocompatible plastic. The adhesion promoter acts as an adhesive, thus irreversibly bonding the cover to the grid structure. It has proven particularly advantageous to use polyurethane as the adhesion promoter.

Preferably, the grid structure is coated with the adhesion promoter using a dip-coating process. Such a process is particularly simple and quick to perform and is characterized by high process reliability. The grid structure is immersed in a container filled with the adhesion promoter, so that the adhesion promoter adheres to the grid elements of the grid structure. The cells of the grid structure generally remain free of adhesion promoter and are therefore not sealed by the adhesion promoter.

In a preferred variant of the method according to the invention, a particularly effective fixation of the cover to the grid structure is achieved by the adhesion promoter and the cover each comprising a plastic material. The two plastics of the adhesion promoter and the cover bond easily to each other, creating a firm connection to the grid structure. This is particularly effective if the plastic material, as provided in preferred variants, comes from the same material group. In particular, both the adhesion promoter and the cover can be made of polyurethane.

The advantages and preferred embodiments listed with regard to the medical device are to be transferred analogously to the method and vice versa.

• 1: eine perspektivische Darstellung einer Gitterstruktur einer erfindungsgemäßen medizinischen Vorrichtung nach einem bevorzugten Ausführungsbeispiel.

The invention is explained in more detail below using an exemplary embodiment with reference to the attached figure. It shows:

• 1 : a perspective view of a lattice structure of a medical device according to the invention according to a preferred embodiment.

The attached figure shows a medical device 2 suitable for insertion into a hollow body organ. For this purpose, the medical device 2 has, in particular, a lattice structure 10 that is compressible and expandable. In other words, the lattice structure 10 can assume a delivery state in which the lattice structure 10 has a relatively small cross-sectional diameter. The lattice structure 10 is preferably self-expanding, so that the lattice structure 10 automatically expands to a maximum cross-sectional diameter without the influence of external forces. For this purpose, the lattice structure 10 preferably has a shape-memory alloy or is formed from such a material. The state in which the lattice structure 10 has the maximum cross-sectional diameter corresponds to the expanded state. In this state, the lattice structure 10 exerts no radial forces.

1 shows the lattice structure 10 in the expanded state. It is clearly visible that the lattice structure 10 is essentially cylindrical. It is also possible for the lattice structure 10 to have a geometry other than cylindrical in some sections. For example, the lattice structure 10 can be funnel-shaped at least at one proximal end.

In 1 The lattice structure 10 has three regions: a central region 20, a first axial region 21, and a second axial region 22. The central region 20 comprises a cover 16, which is arranged on the outside of the lattice structure 10. It is possible for the cover 16 to also be arranged on the inside of the lattice structure 10. The cover 16 spans the entire lattice structure 10 and covers in particular cells 15. The cover 16 may extend along the entire grid structure 10 or only in certain areas. For example, one axial area or both axial areas 21, 22 of the grid structure 10 may be cover-free, as shown in 1 is shown.

Furthermore, the lattice structure 10 has a different cross-sectional diameter in sections. Specifically, the lattice structure 10 or the cover 16 is funnel-shaped in the central region 20, i.e., it has a taper 23 in the central region 20. It is possible for the lattice structure 10 or the cover 16 to be conically tapered or conically widened in the central region 20 and/or in one of the axial regions 21, 22. It is possible for the lattice structure 10 or the cover 16 to have a round, elliptical, or other spherical shape in the central region 20 and/or in one of the axial regions 21, 22. In other words, the lattice structure 10 in the embodiment according to 1 In a side view, it has an hourglass-like geometry. In an alternative embodiment, the lattice structure 10 can have several tapers 23 in the axial direction.

Such a configuration is advantageous for medical devices used as thrombus traps or, more generally, as thrombectomy devices.

In such cases, the lattice structure 10 can essentially form a basket-like structure.

The lattice structure 10 is formed in one piece. The lattice structure 10 is preferably produced from a tubular blank, for example by laser cutting. Individual lattice elements or webs 11, 12, 13, 14 of the lattice structure 10 are exposed by the laser cutting process. The areas removed from the blank form cells 15 of the lattice structure 10. Four webs 11, 12, 13, 14 each extend from a web connector 17, with each web 11, 12, 13, 14 being assigned two cells 15. The webs 11, 12, 13, 14 each delimit the cells 15.

The cover-free areas 21, 22 also enable good coupling to a transport wire 19. In addition, the edge cells, which hardly participate in a cover 16 of an aneurysm anyway, but are intended to anchor it in a blood vessel, thus offer a high permeability, so that the inner walls of the vessel in this area are well supplied with nutrients.

The cover 16 is made of an electrospun fabric and is therefore characterized by a particularly thin wall thickness. At the same time, the cover 16 is sufficiently stable to accommodate the expansion of the lattice structure 10.

The cover 16 has a plurality of pores of different sizes, i.e., completely free through-openings. The pores are not shown in the figures. The cover 16 has a porosity such that, when the lattice structure 10 is implanted, it essentially completely covers or fills the internal cross-section of a hollow body organ, in particular a blood vessel. In other words, the cover 16 is completely closed in cross-section. The porosity is adjusted such that the cover 16, on the one hand, forms a barrier against flow and, on the other hand, simultaneously allows the passage of nutrients and the supply of the transport wire 19. In particular, the cover 16 covers at least 70%, in particular at least 80%, in particular at least 90% of a cross-sectional area of the hollow body organ, in particular the blood vessel.

The cover 16 is preferably completely and irreversibly connected to the grid structure 10. Specifically, the cover 16 is preferably bonded to the webs 11, 12, 13, 14, for example, by means of an adhesion promoter applied to the grid structure 10 by a dip-coating process.

It is possible for the adhesion promoter, which is preferably applied to the grid structure 10 by the aforementioned dip-coating process, to adhere to the grid structure 10 in a substantially form-fitting manner. Due to the plastic material of the material group, the cover 16 then bonds to the adhesion promoter, preferably in a material-to-material manner. Overall, an irreversible bond is thus established between the grid structure 10 and the cover 16.

Furthermore, it is possible for the application of the cover 16 to the lattice structure 10 by the electrospinning process to be followed by a laser cutting process. Specifically, the pores of the cover 16 can be reworked by laser cutting. In particular, it is conceivable to individually adapt the pore shape and/or the pore size by a laser cutting process. The pore size of individual pores can, for example, be specifically increased. Furthermore, the cover 16 can be structured as a whole, in particular by the laser cutting process. Openings can also be introduced in the central region 20 of the cover 16 or the lattice structure 10, in particular by laser cutting. for example, to allow blood flow into branching blood vessels.

The electrospinning process creates multiple threads that are irregularly aligned with one another. Pores are formed in the process. To ensure sufficient flexibility and easy insertion of the medical device 2 into very small blood vessels, the threads must have a thread diameter between 1 µm and 2 µm, resulting in pores with comparatively small pore sizes. However, some pores can be sufficiently large to ensure blood permeability. Specifically, the pores have a diameter of at least 31 µm.

A special feature of the electrospinning process is that the cover has 16 points where only two threads cross each other. This results in the cover having a very thin wall thickness and is therefore highly flexible.

The high flexibility of the cover 16, combined with the high flexibility of the lattice structure 10, allows the medical device 2 to be introduced into a blood vessel through very small delivery catheters. In particular, delivery catheters with a size of 2 French can be used.

To ensure good visibility of the cover 16 under X-ray control, the cover 16 has an X-ray marker 18 at each axial end. Specifically, the X-ray markers 18 can be formed as X-ray-visible sleeves, for example, made of platinum or gold.

List of reference symbols

2

medical device

10

Lattice structure

11

Grid element

12

Grid element

13

Grid element

14

Grid element

15

cell

16

cover

17

web connector

18

X-ray markers

19

Transport wire

20

middle range

21

first axial area

22

second axial area

23

rejuvenation

Claims (16)

Medical device (2) for the treatment of aneurysms in cerebral blood vessels, comprising a compressible and expandable lattice structure (10) made of lattice elements (11, 12, 13, 14) forming cells (15), wherein the lattice structure (10) comprises, at least in sections, a cover (16) made of an electrospun fabric, which, in an implanted state of the lattice structure (10), reduces the blood flow through the hollow body organ by means of the lattice structure (10) in the region of the cover (16), wherein the lattice structure (10) is formed with a taper (23) in a central region (20), and wherein at least the central region (20) comprises the cover (16), wherein the cover (16) has a porosity with pores having a size of at most 750 µm ² and comprises at least 15 pores having a ^size of at least 30 µm ² , and wherein the cover (16) has a blood-permeable and a blood-impermeable area. Medical device (2) according to Claim 1 , characterized in that the cover (16) in the expanded state of the lattice structure (10) covers a cross-sectional area of the hollow body organ to at least 70%, in particular to at least 80%, in particular to at least 90%. Medical device (2) according to Claim 1 or 2 , characterized in that at least 60%, in particular at least 70%, in particular at least 80% of the surface of the cover (16) is formed by pores which have an inscribed circle diameter of at least 30 µm. Medical device (2) according to one of the preceding claims, characterized in that the cover (16) is formed from irregularly arranged net-like threads which have a thread thickness between 1 µm and 2 µm. Medical device (2) according to one of the preceding claims, characterized in that the cover (16) is arranged on an outer side and/or inner side of the grid structure (10). Medical device (2) according to one of the preceding claims, characterized in that the cover (16) with the grid structure (10) is irreversibly, in particular cohesively, connected. Medical device (2) according to one of the preceding claims, characterized in that the cover (16) is formed from a plastic material, in particular from a polyurethane. Medical device (2) according to one of the preceding claims, characterized in that the cover (16) has X-ray-visible markers (18), in particular X-ray-visible sleeves, at least at the longitudinal ends. Medical device (2) according to one of the preceding claims, characterized in that the grid elements (11, 12, 13, 14) are coated with an adhesion promoter, in particular polyurethane, wherein the adhesion promoter forms the particularly material-locking connection of the cover (16) to the grid structure (10). Medical device (2) according to one of the preceding claims, characterized in that the grid elements (11, 12, 13, 14) form webs which are integrally coupled to one another by web connectors (17) or form wires which are interwoven with one another. Medical device (2) according to one of the preceding claims, characterized in that the lattice structure (10) forms a cylindrical and/or funnel-shaped hollow body at least in sections. Medical device (2) according to one of the preceding claims, characterized in that the medical device is arranged in a compressed state on a transport wire (19) so that the medical device is axially displaceable within a supply tube, wherein the supply tube has an inner diameter of a maximum of 0.7 mm, in particular a maximum of 0.52 mm, in particular a maximum of 0.42 mm. Medical device (2) according to one of the preceding claims, characterized in that the medical device is precisely compatible with a 2Fr catheter. A method for producing a medical device (2) for treating aneurysms in cerebral blood vessels according to one of the preceding claims, wherein the method comprises the following steps: a. Providing a compressible and expandable lattice structure (10) made of lattice elements (11, 12, 13, 14) that define closed cells (15) of the lattice structure (10); b. Coating the lattice structure (10) with an adhesion promoter, in particular made of polyurethane; and c. Applying a cover (16) to the lattice structure (10) by an electrospinning process. Procedure according to Claim 14 , characterized in that the coating of the grid structure (10) with the adhesion promoter is carried out by a dip coating process. Procedure according to Claim 14 or 15 , characterized in that the adhesion promoter and the cover (16) each comprise a plastic material, in particular from the same material group, preferably polyurethane.