Medical device; method for producing a medical device

Abstract

The invention relates to a medical device (10) for treating vascular lesions, in particular aneurysms, having a compressible and expandable lattice structure (11) composed of lattice elements (12) which delimit lattice openings (13), wherein the lattice structure (11) is covered at least in sections by a membrane (14), in particular an electrospun membrane, wherein in at least one lattice opening (13) the membrane (14) has at least one sealing region (15) and at least one predetermined opening region (16) having a smaller wall thickness than the sealing region (15), wherein in the implanted state the predetermined opening region (16) of the membrane (14) opens by way of a pressure gradient established between a fluid pressure in an inner lumen of the lattice structure (11) and a fluid pressure outside of the lattice structure (11), in order to increase the fluid flow through the membrane (14).

Description

[0001] Medical device; method for manufacturing a medical device

[0002] Description

[0003] The invention relates to a medical device for the treatment of vascular lesions, in particular aneurysms, with a compressible and expandable lattice structure made of lattice elements that delimit lattice openings, wherein the lattice structure is covered at least in sections with a membrane, in particular an electrospun membrane.

[0004] When treating lesions with medical implants that have a membrane, the problem often arises that the side branches branching off a main vessel are covered by the membrane and thus shielded from the blood flow. This prevents the supply of oxygen and nutrients to subsequent tissue areas.

[0005] A medical implant with a membrane is known, for example, from EP 2 678 466 B1. However, this implant is either only suitable for the treatment of lesions located remotely from a branching blood vessel or must be placed by a surgeon in a complex procedure in such a way that the branching blood vessel is not covered.

[0006] The invention is therefore based on the object of providing a medical device for treating vascular lesions, in particular aneurysms, which, on the one hand, enables efficient treatment of the vascular lesions and, on the other hand, ensures blood flow into branching blood vessels. Furthermore, the invention is based on the object of providing a method for producing such a medical device. According to the invention, this object is achieved by a medical device having the features of claim 1. With regard to the method, this object is achieved by claim 13.

[0007] Specifically, this object is achieved by a medical device for treating vascular lesions, in particular aneurysms, comprising a compressible and expandable lattice structure composed of lattice elements that define lattice openings. The lattice structure is covered, at least in sections, with a membrane, in particular an electrospun membrane. The membrane has, in at least one lattice opening, at least one sealing region and at least one desired opening region, which has a smaller wall thickness than the sealing region. In the implanted state, the desired opening region of the membrane opens due to a pressure gradient established between a fluid pressure in an inner lumen of the lattice structure and a fluid pressure outside the lattice structure, increasing the fluid flow through the membrane.

[0008] The invention has several advantages.

[0009] The medical device thus enables the efficient treatment of vascular lesions. For this purpose, the device comprises a membrane with at least one sealing region in at least one mesh opening. It is possible for at least one sealing region to be arranged in each mesh opening covered by the membrane. Alternatively, at least one sealing region can be provided in some or some selected mesh openings. The sealing region is designed to largely reduce blood flow into the aneurysm, allowing the blood to clot within the aneurysm and form a thrombus. In this respect, the aneurysm is naturally obliterated, with the membrane or sealing region ensuring that the thrombus cannot leave the aneurysm.

[0010] Furthermore, the medical device ensures that blood flow into branching blood vessels is guaranteed. For this purpose, the membrane has at least one desired opening region in at least one grid opening next to the sealing region. Furthermore, at least one desired opening region can be arranged in each grid opening covered by the membrane. Alternatively, at least one desired opening region can be provided in some selected grid openings. The desired opening region serves to ensure blood flow into those blood vessels branching off from a main vessel that are covered by the membrane of the medical device. In other words, the desired opening region ensures sufficient blood flow in branching vessels so that they are supplied with oxygen and nutrients. The wall thickness of the sealing region is preferably greater than the wall thickness of the desired opening region.In other words, the sealing area is thicker than the target opening area, or the target opening area is thinner than the sealing area. Due to the varying wall thicknesses of the membrane, the area with the thinner wall thickness, the target opening area, defines a region of the membrane that opens predictably under a certain load.

[0011] The load on the membrane is created by the pressure gradient that occurs in the implanted state between the fluid pressure in the inner lumen of the lattice structure and the fluid pressure outside the lattice structure. This means that the membrane becomes more permeable to fluid when a corresponding pressure gradient exists, as this leads to the opening of the desired opening area. In the implanted state, those desired opening areas of the membrane that span a branching blood vessel open, as at these points there is a corresponding pressure gradient between the main blood vessel and the vessel branching off from it. The blood flowing through the main vessel into the branching blood vessel has a fluid pressure that forces the blood into the branching blood vessel.The membrane's target opening areas are designed such that this fluid pressure is sufficient to open the target opening area sufficiently to permit blood flow to the membrane at points where blood vessels branch off. For example, a corresponding pressure gradient exists when the blood pressure in a branching vessel is at least 50% lower than in the main vessel. If the blood pressure in the main vessel is approximately 120 / 80 mmHg and the blood pressure in the branching vessel is approximately 60 / 40 mmHg, this leads to the opening of those target opening areas located at the transition between the main vessel and the branching vessel.

[0012] The opening of the target opening areas can specifically be understood as a tearing of the target opening areas or a tearing of that area of ​​the membrane with a reduced wall thickness. Furthermore, the opening of the target opening areas can be understood as an expansion, widening or local widening of these areas. The target opening areas preferably open locally, i.e. limited to their area. Additionally or alternatively, it is possible for the areas between the target opening areas to tear, so that a larger area opens up in order to increase the flow cross-section through the membrane. It is also conceivable for the entire area of ​​the membrane within a grid opening to give way to the load due to the local weak points in the membrane and thus open.

[0013] In areas where the medical device covers an aneurysm, however, such a pressure gradient is not present, so that the target opening area of ​​the membrane remains closed or does not tear, expand, or locally widen. The target opening area remains closed if the blood pressure in the main vessel and the blood pressure in the aneurysm are essentially the same or differ only slightly. Such a small pressure difference exists, for example, if the blood pressure in the aneurysm is at most 15% lower than in the main vessel. If, for example, the blood pressure in the main vessel is approximately 120 / 80 mmHg and the blood pressure in the aneurysm is approximately 100 / 75 mmHg, the target opening areas located at the transition between the main vessel and the aneurysm remain closed. When closed, the target opening area is essentially impermeable to liquids or only very slightly permeable to liquids.This effectively shields the aneurysm from the blood flow within the blood vessel. This shielding does not necessarily involve a complete fluid barrier. Rather, a significantly reduced fluid exchange between the blood within the aneurysm and the blood within the main vessel can be maintained. This ensures that the aneurysm wall is supplied with nutrients and oxygen, preventing it from degrading.

[0014] A further advantage of the medical device according to the invention is that it is not absolutely necessary for a surgeon to precisely determine the position of the device when treating vascular lesions. In particular, the surgeon does not have to ensure that a device of a specific length is inserted or that specific functional areas of the device are precisely positioned within the vessel to prevent branching blood vessels from being covered. Rather, it is possible to use the medical device in a standard length for any type of aneurysm, since the device allows blood flow into branching blood vessels even when the device covers the branching blood vessel.

[0015] The desired opening areas are preferably introduced into the membrane after the membrane has been applied to the grid structure. In this case, at least one desired opening area is introduced into the membrane in at least one grid opening. The introduction of the desired opening areas into the membrane is preferably carried out by partially removing the membrane material, so that areas with a reduced wall thickness or thickness are created. The desired opening areas therefore form local weakenings in the membrane material or partially perforated areas in the membrane. In the context of this application, partially perforated areas are understood to mean local areas on the membrane with a reduced wall thickness that partially, i.e., do not completely, penetrate the membrane or do not form through holes. The desired opening area can be regarded as a subsequently processed area, while the sealing area of ​​the membrane is unprocessed, i.e.,the membrane material in the sealing area is not removed.

[0016] Because the membrane's target opening areas only open when a corresponding pressure gradient is present and otherwise remain closed, it is possible to process the membrane of each grid opening essentially the same. This means that the target opening and sealing areas of the membrane are essentially the same for each grid opening. The target opening area advantageously has the same wall thickness within each grid opening covered by the membrane. This simplifies the manufacture of the medical device. The post-processing of the membrane or the introduction of the target opening areas into the membrane can be essentially the same for each grid opening.

[0017] Another advantage is that the selective opening of the target opening areas in specific regions of the medical device allows adaptation to patient-specific conditions. The opening of the target opening areas is limited to those regions where a vessel branches off from a main vessel. Those target opening areas that are located near an aneurysm during use remain closed. Consequently, despite the consistent design of the membrane in each mesh opening, the medical device fulfills different functions in different regions. The desired function of the membrane in a specific region is determined by the anatomical conditions.

[0018] A laser, particularly a UV laser, can be used to ablate the membrane material. By adjusting the laser parameters, such as the energy density of the laser beam and / or the number of repetitions of the laser process, the amount of membrane material removed can be adjusted depending on the membrane material. The energy density depends, for example, on the power, pulse frequency, and / or scan speed of the laser. The energy density can be adjusted such that partial perforation of the membrane is achieved, thereby forming the desired opening areas. Specifically, the wall thickness of the desired opening areas can be adjusted.

[0019] Particularly preferably, the membrane is manufactured by electrospinning, or the membrane is preferably formed from electrospun material. In this case, the electrospun material can be partially removed, for example, using a UV laser to form the desired opening areas. Other membrane designs are possible.

[0020] Preferred embodiments of the invention are specified in the subclaims.

[0021] The membrane preferably comprises a plurality of layers, in particular electrospun layers, which are arranged one above the other in the radial direction of the lattice structure, wherein the sealing region has a greater number of layers than the desired opening region. In this embodiment, the wall thickness of the sealing region and the desired opening region is defined by the number of layers of the membrane, wherein a high number of layers means a great wall thickness. Individual layers of the membrane can, for example, be ablated using the laser to form the desired opening region. As a result, the desired opening region has a reduced wall thickness compared to the sealing region. The number of ablated layers and thus the wall thickness of the desired opening region can be adjusted using the laser parameters, such as the power, the pulse frequency, the scanning speed and / or the number of repetitions.The advantage here is that the desired opening area can be designed by varying the number of layers so that it opens as a result of a corresponding pressure gradient. This ensures blood flow into branching vessels spanned by the membrane.

[0022] Furthermore, the membrane can be formed from abluminal and luminal layers. The luminal layer faces an inner lumen of the lattice structure, while the abluminal layer faces away from the inner lumen of the lattice structure. By processing the membrane, for example, with a laser, the abluminal layers of the membrane can be removed in the area of ​​the desired opening regions, while the luminal layers are not, or only partially, processed or removed. The desired opening regions thus essentially comprise the luminal layers of the original or unprocessed membrane.

[0023] Furthermore, the layers of the membrane can be formed from fibers, in particular electrospun fibers, wherein the fibers of the desired opening region tear due to the pressure gradient to increase the fluid flow through the membrane. In other words, the layers of the membrane are preferably designed as fiber layers. The desired opening region can have a smaller number of fiber layers than the sealing region and is thus thinner. If a corresponding pressure gradient is present, the fibers of the desired opening region tear, causing the desired opening region to open. In the process, the fibers fray or loose fiber ends form. In this way, the supply of branching vessels spanned by the membrane can be achieved.

[0024] In one embodiment, the sealing region comprises a larger proportion of the total surface area of ​​the membrane per grid opening than the desired opening area. In other words, the desired opening area occupies a smaller surface area per grid opening than the sealing region. This ensures that the membrane is only weakened locally. In regions where the medical device covers an aneurysm, there is no pressure gradient or the pressure gradient is not sufficiently high to open the locally weakened regions of the membrane. In the unopened state, these regions are essentially impermeable to liquids or only very slightly permeable to liquids. The membrane is therefore so stable that it can efficiently fulfill its function of largely reducing blood flow into the aneurysm.Alternatively, it is conceivable that the target opening areas have a larger proportion of the total area of ​​the membrane per grid opening than the sealing area.

[0025] The desired opening area is preferably formed as a recess in the sealing area of ​​the membrane, which partially penetrates the sealing area in the radial direction of the lattice structure. The sealing area is advantageously only partially perforated by the recess, rather than completely. For example, the desired opening area can be formed as a depression in the sealing area. The advantage here is that, although the recess has a thinner wall than the sealing area, the recess is essentially impermeable to liquids or only very slightly permeable to liquids when closed. This allows the aneurysm to be largely shielded from the blood flow.

[0026] Advantageously, the membrane has several target opening areas per grid opening, which are arranged at a distance from one another and / or are each delimited by the sealing area. The target opening areas can be arranged substantially uniformly within a grid opening. Furthermore, the multiple target opening areas are each surrounded by the sealing area. This advantageously allows the degree of blood permeability of the membrane to be adjusted not only by the size of the target opening areas, but also by their number and distribution across the membrane.

[0027] Furthermore, the desired opening region can be substantially round and have a diameter of between 10 pm and 300 pm, in particular at least 100 pm, in particular at least 200 pm. The desired opening regions can be circular or oval. It is possible for a plurality of desired opening regions, which are in particular round, to be arranged within a grid opening. Furthermore, the round desired opening regions within a grid opening can be of different sizes or have different diameters. For example, a plurality of desired opening regions with a diameter of approximately 200 pm can be arranged within a grid opening, with further desired opening regions with a smaller diameter of approximately 100 pm being arranged in the spaces between these desired opening regions. Consequently, a special arrangement ora specific pattern of the target opening areas can be selected that positively influences the opening behavior of the target opening areas.

[0028] In a further embodiment, the desired opening region is essentially linear and extends within the grid openings. The linear desired opening region can be essentially straight or curved. The advantage here is that the linear shape of the desired opening regions allows a selective opening region of the membrane to be set. If the desired opening region within a grid opening is curved or U-shaped, for example, it can form a type of flap that can release blood flow through the membrane. If a corresponding pressure gradient is present, the desired opening region tears along its linear shape, opening a flap that releases blood flow into a branching vessel.

[0029] The wall thickness of the sealing region is preferably at least 20%, in particular at least 30%, in particular at least 40%, in particular at least 50%, in particular at least 60%, greater than the wall thickness of the desired opening region. The difference between the wall thickness of the sealing region and the wall thickness of the desired opening region is advantageously selected such that the membrane is only locally weakened. Furthermore, the wall thickness of the desired opening region can be at least 40%, in particular at least 50%, in particular at least 60%, in particular at least 70%, in particular at least 80%, less than the wall thickness of the sealing region.

[0030] Furthermore, the sealing region preferably has a wall thickness between 5 pm and 100 pm, in particular at least 10 pm, in particular at least 25 pm, in particular at least 50 pm. The wall thickness of the sealing region can be selected or adjusted such that efficient shielding of an aneurysm from blood flow is enabled. The desired opening regions further preferably have a wall thickness between 1 pm and 45 pm, in particular at most 25 pm, in particular at most 10 pm, in particular at most 5 pm, in particular at most 2 pm. The wall thickness of the desired opening region can be selected or adjusted such that it opens as a result of a corresponding pressure gradient.

[0031] The desired opening region can have a depth between 1 pm and 40 pm, in particular at least 10 pm, in particular at least 20 pm, in particular at least 30 pm. The depth of the desired opening region extends in the radial direction of the lattice structure. The depth of the desired opening region is preferably selected such that a corresponding pressure gradient causes the desired opening region to open. In this way, the supply of branching vessels spanned by the membrane can be ensured.

[0032] The sealing region and the desired opening region of the membrane advantageously each have a plurality of pores, wherein the pore size of the pores in the desired opening region is larger than the pore size of the pores in the sealing region. For example, the fibers of the membrane, in particular the electrospun membrane, can lie loosely on top of one another and form pores with an irregular shape. It is conceivable for several fiber layers of the membrane to have a substantially identical or different porosity. The pores of the desired opening region can be designed to be larger than the pores in the sealing region in such a way that the opening behavior of the desired opening region is positively influenced in the event of a pressure gradient.

[0033] According to the independent claim 13, the invention relates to a method for producing the medical device according to the invention. In this method, a compressible and expandable lattice structure comprising lattice elements that define lattice openings is first arranged on a mandrel. The lattice structure is essentially tubular. The lattice elements of the lattice structure preferably comprise or consist of a self-expanding shape memory alloy such as nitinol. It is possible for the lattice structure to be monolithic, with the lattice elements of the lattice structure forming webs that define lattice openings in the lattice structure, which are designed as cells. Alternatively, it is conceivable for the lattice structure to comprise interwoven wires, with the wires forming the lattice elements of the lattice structure and defining lattice openings in the lattice structure, which are designed as meshes.

[0034] After the grid structure has been arranged on the mandrel, at least one layer is applied around the grid structure to form a membrane by electrospinning. First, a fiber layer of the membrane is produced by electrospinning, with the electrospun fibers being deposited on the grid structure. For this purpose, a polymer solution is finely metered at an emitter electrode. By applying an electric field, a polymer jet forms, which is accelerated towards a collector. This acceleration directs the polymer jet and a polymer fiber forms, which becomes thinner with increasing length until it is deposited on the collector electrode (the grid structure). The polymer solution can be formed from one or more polymers. If the membrane is to be formed from several fiber layers, a further fiber layer can be applied to an already formed fiber layer.This process is repeated until the membrane has the desired wall thickness. It is possible that the fiber layers are made of different polymers.

[0035] Subsequently, the membrane is partially perforated such that the membrane has at least one sealing area and one desired opening area in at least one grid opening, wherein the wall thickness of the desired opening area is smaller than the wall thickness of the sealing area. The partial perforation of the membrane is preferably carried out using a UV laser. By appropriately adjusting the laser parameters, such as the energy density of the laser beam and / or the number of repetitions of the laser process, the wall thickness of the desired opening area can be adjusted. This is designed such that it opens as a result of a corresponding pressure gradient.

[0036] The invention will be explained in more detail using exemplary embodiments in conjunction with schematic drawings. These show various exemplary embodiments of the medical device according to the invention with different desired opening areas;

[0037] Fig. 2a, 2b enlarged sections of another inventive

[0038] Embodiment of the medical device, wherein a plurality of desired opening areas are shown within a grid opening;

[0039] Fig. 3 is a microscopic image of another embodiment of the medical device according to the invention, wherein the membrane is produced by electrospinning;

[0040] Fig. 4 is an enlarged section of the micrograph of Fig. 3, showing the fibers of the electrospun membrane; and

[0041] Fig. 5 shows a further embodiment of the medical device according to the invention in the implanted state.

[0042] Fig. 1a to 1c show exemplary embodiments of the medical device 10 according to the invention. The medical device 10 is used for the endovascular treatment of, in particular, intracranial or peripheral, aneurysms 100. Other areas of application are possible. Thus, the medical device can

[0043] 10 can be used to treat fistulas, dissections or stenoses.

[0044] The device 10 has a compressible and expandable lattice structure

[0045] 11. In other words, the lattice structure 11 can be transformed from a radially compressed state to a radially expanded state. Specifically, the lattice structure 11 is self-expanding. Alternatively, the lattice structure 11 is balloon-expandable.

[0046] The grid structure 11 is formed from grid elements 12 that define grid openings 13. In the exemplary embodiments according to Figs. 1a to 1c, the grid structure 11 comprises interwoven wires that form meshes. Alternatively, the grid structure 11 can be formed from monolithic webs that define cells.

[0047] From Figs. 1a to 1c it is further apparent that the medical device 10 or the grid structure 11 is partially covered with a membrane 14. The membrane 14 extends completely around the circumference of the grid structure 11. The proximal and distal ends of the grid structure 11 are each free of cover or not covered by the membrane 14.

[0048] The membrane 14 has a sealing region 15 for each grid opening 13. A sealing region 15 is arranged within each grid opening 13, which is covered by the membrane 14. The sealing region 15 serves to shield an aneurysm 100 from the blood flow. The sealing region 15 is essentially impermeable to blood.

[0049] Furthermore, the membrane has several target opening areas 16 for each grid opening 13. Within each grid opening 13 covered by the membrane 14, several target opening areas 16 are arranged. The target opening areas 16 define a region of the membrane 14 for each grid opening 13 that opens predictably and specifically under a certain load, such as fluid pressure.

[0050] The desired opening regions 16 each have a smaller wall thickness than the sealing region 15. In other words, the desired opening regions 16 are thinner than the sealing region 15, or the desired opening regions 16 have a smaller thickness than the sealing region 15.

[0051] The desired opening regions 16 of the membrane 14 are further configured such that, in the implanted state (cf. Fig. 5), they open due to a pressure gradient in order to increase the fluid flow through the membrane 14. During use of the medical device 10, the pressure gradient is established between a fluid pressure in an inner lumen of the lattice structure 11 and a fluid pressure outside the lattice structure 11. For example, in the implanted state of the device 10, a corresponding pressure gradient exists at points on the membrane 14 that are located between a main blood vessel 101 and a vessel 102 branching off from it. The desired opening regions 16 of the membrane 14 are designed such that such a pressure gradient is sufficient to open the desired opening region 16 wide enough to allow blood to pass through them. Specifically, the desired opening regions 16 rupture as a result of the pressure gradient, allowing blood to flow through the membrane 14.

[0052] In areas where the medical device 10 covers an aneurysm 100 during use, the target opening area 16 of the membrane 14 remains intact because a corresponding pressure gradient is not present. In other words, the target opening area 16 remains closed or does not open in this case, making the target opening area 16 essentially impermeable to fluids. This shields the aneurysm 100 from blood flow within the blood vessel 101.

[0053] Figures 3 and 4 show that the membrane 14 comprises several electrospun layers 17. In other words, all layers 17 of the membrane 14 are formed from or consist of an electrospun material. The sealing region 15 has a larger number of electrospun layers 17 than the desired opening region 16. The electrospun layers 17 are arranged one above the other in the radial direction of the lattice structure 11.

[0054] It can also be seen in Figs. 3 and 4 that the layers 17 of the membrane 14 are formed from electrospun fibers 18. The fibers 18 of the desired opening area 16 are designed such that they tear under load.

[0055] Specifically, the fibers 18 tear due to a pressure gradient, causing the fibers 18 to fray or form loose ends.

[0056] The fibers 18 of the membrane are formed from or consist of a polymer. The fibers can be formed, for example, from perfluorinated or partially fluorinated polymers (e.g., PTFE, PVDF), polyolefin (e.g., PP, PE), polyurethane (e.g., thermoplastic polyurethane, hydrophilic polyurethane), polyamide (e.g., PA6.6), polyester (e.g., PLA, PLGA, PET), polysulfone (e.g., PSU), polyetheretherketone (PEEK), biological and / or protein-based polymers.

[0057] Furthermore, it can be seen in Fig. 3 that the sealing region 15 has a larger proportion of a total area of ​​the membrane 14 per grid opening 13 than the desired opening region 16. Within each grid opening 13, the membrane 14 is formed from a sealing region 15 and several desired opening regions 16, wherein the proportion of the sealing region 15 in the membrane 14 is larger.

[0058] Specifically, the desired opening area 16 is formed as a recess in the sealing area 15 of the membrane 14. The recess only partially, i.e., not completely, penetrates the sealing area 15 in the radial direction of the lattice structure 11. The recesses are specifically formed as perforations that are introduced into the sealing area 15 of the membrane 14 after the production of the electrospun membrane 14.

[0059] Figs. 1 to 3 further show that the membrane 14 has a plurality of desired opening regions 16 for each grid opening 13. The desired opening regions 16 are spaced apart from one another and each delimited by the sealing region 15. Fig. 3 shows that 25 desired opening regions 16 are distributed within a grid opening 13 and are each surrounded by the sealing region 15.

[0060] In the exemplary embodiments according to Fig. 1a and Figs. 2a and 2b, the desired opening area 16 is round, or rather, it can be seen that the desired opening areas 16 have the shape of a circle. The desired opening areas 16 are arranged in different patterns within the grid openings 13.

[0061] Fig. 2a shows that the point-shaped target opening regions 16 within a grid opening 13 of the grid structure 11 have essentially the same diameter. Specifically, the target opening regions 16 have a diameter of approximately 200 μm. The target opening regions 16 are each bounded by the sealing region 15.

[0062] Fig. 2b shows that the desired opening regions 16 within a grid opening 13 have different diameters. Several desired opening regions 16 have a diameter of approximately 200 pm, with further desired opening regions 16 with a diameter of approximately 100 pm being arranged in the spaces between them. All desired opening regions 16 are each surrounded by the sealing region 15. In the exemplary embodiments according to Figs. 1b and 1c, the desired opening region 16 is linear and extends within the grid openings 13. Several linear desired opening regions 16 are arranged for each grid opening 13.

[0063] In Fig. 1b, the desired opening regions 16 are essentially linear. The multiple linear desired opening regions 16 within a grid opening 13 have different lengths.

[0064] In Fig. 1c, the target opening regions 16 within a grid opening 13 are curved or U-shaped. If the U-shaped target opening region 16 tears along its curved line shape as a result of a pressure gradient, a valve opens, allowing blood flow into a branching vessel 102.

[0065] In the embodiment according to Figs. 3 and 4, the wall thickness of the sealing region 15 is at least 20% greater than the wall thickness of the desired opening region 16. Specifically, the sealing region 15 has a wall thickness between 50 pm and 100 pm and the desired opening regions 16 have a wall thickness between 1 pm and 50 pm.

[0066] Figures 3 and 4 show that the desired opening area 16 has a specific depth that extends into the membrane 14 or the sealing area 15. The desired opening area 16 has a depth between 1 pm and 40 pm.

[0067] Fig. 4 illustrates that the sealing region 15 and the desired opening region 16 of the membrane 14 each have a plurality of pores 19. It can be seen that the pore size of the pores 19 of the desired opening region 16 is larger than the pore size of the pores 19 of the sealing region 15. In other words, the desired opening region 16 is more porous than the sealing region 15. This results from the different number of fiber layers 17 of the desired opening region 16 and the sealing region 15. It can also be seen that the fibers 18 of the electrospun membrane 14 lie loosely on top of one another, thereby forming the pores 18, which have an irregular shape.

[0068] The method for producing the medical device 10 is explained in more detail with reference to Fig. 1a to lc. First, a compressible and expandable lattice structure 11 is arranged on a mandrel. The lattice structure 11 is formed from lattice elements 12 which define lattice openings 13. Then, a plurality of electrospun fiber layers 17 are applied to the lattice structure 11 to form the membrane 14. Subsequently, a partial perforation of the membrane 14 takes place such that the membrane 14 has a plurality of regions with a reduced wall thickness for each lattice opening 13. These regions are designed as desired opening regions 16, i.e., they form local weakenings in the membrane which open predictably under a corresponding load. The partial perforation takes place by ablating membrane material using a UV laser.The laser parameters, such as the energy density of the laser beam and / or the number of repetitions of the laser process, are adjusted such that the desired amount of membrane material is removed. Specifically, the wall thickness of the target opening areas 16 is adjusted. The target opening areas 16 are then surrounded by unprocessed membrane material, which forms a sealing area 15. The sealing area 15 thus has a greater wall thickness than the target opening areas 16.

[0069] List of reference symbols

[0070] 10 Medical Device

[0071] 11 Lattice structure

[0072] 12 grid elements

[0073] 13 Grille opening

[0074] 14 Membran

[0075] 15 Sealing area

[0076] 16 Target opening range

[0077] 17 layers of the membrane

[0078] 18 fibers of the membrane

[0079] 19 pores of the membrane

[0080] 100 Vascular lesion, aneurysm

[0081] 101 Main vessel

[0082] 102 branching vessel

Claims

Claims 1. Medical device (10) for the treatment of vascular lesions (100), in particular aneurysms, with a compressible and expandable lattice structure (11) made of lattice elements (12) which delimit lattice openings (13), wherein the lattice structure (11) is at least partially covered with a, in particular electrospun, membrane (14) is covered, characterized in that the membrane (14) has in at least one grid opening (13) at least one sealing area (15) and at least one desired opening area (16) which has a smaller wall thickness than the sealing area (15), wherein the desired opening region (16) of the membrane (14) opens in the implanted state by a pressure gradient which is established between a fluid pressure in an inner lumen of the lattice structure (11) and a fluid pressure outside the lattice structure (11), in order to increase the fluid flow through the membrane (14).

2. Medical device according to claim 1, characterized in that the membrane (14) comprises a plurality of, in particular electrospun, layers (17) which are arranged one above the other in the radial direction of the lattice structure, wherein the sealing region (15) has a larger number of layers (17) than the desired opening region (16).

3. Medical device according to claim 1 or 2, characterized in that the layers (17) of the membrane (14) are formed from, in particular electrospun, fibers (18), wherein the fibers (18) of the desired opening region (16) tear due to the pressure gradient to increase the fluid flow through the membrane (14).

4. Medical device according to one of the preceding claims, characterized in that the sealing area (15) forms a larger proportion of a total area of the Membrane (14) per grid opening (13) than the desired opening area (16).

5. Medical device according to one of the preceding claims, characterized in that the desired opening region (16) is designed as a recess in the sealing region (15) of the membrane (14), which recess partially penetrates the sealing region (15) in the radial direction of the lattice structure (11).

6. Medical device according to one of the preceding claims, characterized in that the membrane (14) has a plurality of desired opening regions (16) for each grid opening (13), which are arranged at a distance from one another and / or are each delimited by the sealing region (15).

7. Medical device according to one of the preceding claims, characterized in that the desired opening region (16) is substantially round and has a diameter between 10 pm and 300 pm, in particular at least 100 pm, in particular at least 200 pm.

8. Medical device according to one of the preceding claims, characterized in that the desired opening region (16) is substantially linear and extends within the grid openings (13).

9. Medical device according to one of the preceding claims, characterized in that the wall thickness of the sealing region (15) is at least 20%, in particular at least 30%, in particular at least 40%, in particular at least 50%, in particular at least 60% greater than the wall thickness of the desired opening region (16).

10. Medical device according to one of the preceding claims, characterized in that the sealing area (15) has a wall thickness between 5 pm and 100 pm, in particular at least 10 pm, in particular at least 25 pm, in particular at least 50 pm, and / or the desired opening regions (16) have a wall thickness between 1 pm and 45 pm, in particular at most 25 pm, in particular at most 10 pm, in particular at most 5 pm, in particular at most 2 pm.

11. Medical device according to one of the preceding claims, characterized in that the desired opening region (16) has a depth between 1 pm and 40 pm, in particular at least 10 pm, in particular at least 20 pm, in particular at least 30 pm.

12. Medical device according to one of the preceding claims, characterized in that the sealing region (15) and the desired opening region (16) of the membrane (14) each have a plurality of pores (19), wherein the pore size of the pores (19) of the desired opening region (16) is larger than the pore size of the pores (19) of the sealing region (15).

13. A method for producing a medical device (10) according to any one of the preceding claims, wherein the method comprises the following steps: a. arranging a compressible and expandable lattice structure (11) made of lattice elements (12) that define lattice openings (13) on a mandrel; b. electrospinning at least one layer around the lattice structure (11) to form a membrane (14); c. partially perforating the membrane (14) such that the membrane (14) has at least one sealing region (15) and one desired opening region (16) in at least one lattice opening (13), wherein the wall thickness of the desired opening region (16) is smaller than the wall thickness of the sealing region (15).

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