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US-12622794-B2 - Medical device for treating aneurysms

US12622794B2US 12622794 B2US12622794 B2US 12622794B2US-12622794-B2

Abstract

The invention relates to a medical device for treating aneurysms, in particular a stent, including a compressible and expandable grid structure made up of grid elements. The grid structure has at least one closed cell ring which includes at most 12, in particular at most 10, in particular at most 8, in particular at most 6 cells directly adjacent to one another in a circumferential direction of the grid structure. The grid structure is provided at least in certain portions with a covering made of an electrospun fabric which has pores of irregular sizes. The covering includes over a surface area of 100 000 μm2 at least 10 pores which have a size of at least 15 μm2. The covering has a biocompatible, in particular antithrombogenic and/or endothelialization-promoting coating.

Inventors

  • Michael Büchert
  • Giorgio Cattaneo

Assignees

  • ACANDIS GMBH

Dates

Publication Date
20260512
Application Date
20200721
Priority Date
20190809

Claims (18)

  1. 1 . A medical device for treatment of an aneurysm comprising: a compressible and expandable mesh structure having at least one closed cell ring which includes at most 12 immediately adjacent cells in a circumferential direction of the mesh structure, wherein the mesh structure is provided, at least in sections, with a covering produced from an electrospun fabric having irregularly sized pores, which are each delimited by filaments, wherein the covering includes at least 10 pores with a size of at least 15 μm 2 over an area of 100000 μm 2 , wherein the covering has a biocompatible coating, which completely sheaths all of the filaments of the covering, wherein at least part of the coating includes fibrin, and wherein at least part of the coating includes heparin.
  2. 2 . The medical device according to claim 1 , wherein the coating has a layer thickness of at least 10 nm.
  3. 3 . The medical device according to claim 1 , wherein one of the covering is cohesively connected to the mesh structure or the coating is cohesively connected to the covering.
  4. 4 . The medical device according to claim 1 , wherein the coating is bonded to a surface of the covering.
  5. 5 . The medical device according to claim 4 , wherein the coating has a thickness between 5 nm and 100 nm.
  6. 6 . The medical device according to claim 1 , wherein the mesh structure includes mesh elements sheathed by a bonding agent which securely connects the covering to the mesh structure.
  7. 7 . The medical device according to claim 1 , wherein the heparin is embedded in the fibrin.
  8. 8 . The medical device according to claim 1 , wherein at least part of the coating is one of admixed with a material of the covering or embedded in the covering.
  9. 9 . The medical device according to claim 1 , wherein the coating has between 0.5 μg/cm 2 and 3 μg/cm 2 of fibrin.
  10. 10 . The medical device according to claim 1 , wherein the coating has between 5 mU/cm 2 and 50 mU/cm 2 of heparin.
  11. 11 . The medical device according to claim 1 , wherein the mesh structure includes mesh elements that form webs coupled together into one piece by web connectors.
  12. 12 . The medical device according to claim 1 , wherein the mesh structure includes mesh elements formed by at least one wire.
  13. 13 . The medical device according to claim 1 , wherein the mesh structure has a closed cell design.
  14. 14 . A medical device for treatment of an aneurysm comprising: a compressible and expandable mesh structure having at least one closed cell ring which includes at most 12 immediately adjacent cells in a circumferential direction of the mesh structure, wherein the mesh structure is provided, at least in sections, with a covering produced from an electrospun fabric having irregularly sized pores which are each delimited by filaments, wherein the covering includes at least 10 pores with a size of at least 15 μm 2 over an area of 100000 μm 2 , wherein the covering has one of an antithrombogenic or endothelialization-promoting coating, at least part of which includes fibrin and which completely sheaths all of the filaments of the covering, and wherein at least part of the coating includes heparin.
  15. 15 . The medical device according to claim 14 , wherein one of the covering is cohesively connected to the mesh structure or the coating is cohesively connected to the covering.
  16. 16 . The medical device according to claim 14 , wherein the mesh structure includes mesh elements that are sheathed by a bonding agent which securely connects the covering to the mesh structure.
  17. 17 . The medical device according to claim 14 , wherein the mesh structure includes mesh elements that form webs coupled together into one piece by web connectors.
  18. 18 . The medical device according to claim 14 , wherein the mesh structure includes mesh elements formed by at least one wire.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a National Stage of International Application No PCT/EP2020/070501, fled Jul. 21, 2020, which application claims priority to commonly owned German Patent Application No. 102019121562.5, filed on Aug. 9, 2019, which applications are incorporated herein by reference in their entirety. TECHNICAL FIELD The invention relates to a medical device for the treatment of aneurysms, in particular a stent, in accordance with the preamble of patent claim 1. An example of a medical device of the aforementioned type is known from the Applicant's document WO 2014/177634 A1. BACKGROUND WO 2014/177634 A1 describes a highly flexible stent which has a compressible and expandable mesh structure, wherein the mesh structure is formed in one piece. The mesh structure comprises closed cells which are each delimited by four mesh elements. The mesh structure has at least one cell ring which comprises between three and six cells. Furthermore, to the Applicant's knowledge, stents with mesh structures are known which are produced from a single wire. The wire is braided with itself in order to form a tubular network. At the axial ends of the tubular network, the wire is curved round so that loops which act atraumatically are formed. The axial ends may flare outwards in a funnel shape. The mesh elements of such mesh structures are therefore formed by at least one wire, wherein the respective wire sections which extend between two points of intersection in an expanded state of the mesh structure are defined as mesh elements. The known medical device is particularly suitable for the treatment of aneurysms in small cerebral blood vessels. Blood vessels of this type have a very small cross sectional diameter and are often highly tortuous. For this reason, the known stent is highly flexible in configuration, so that on the one hand it can be compressed to a very small cross sectional diameter, and on the other hand it has a high bending flexibility, which enables it to be delivered to small cerebral blood vessels. For the treatment of aneurysms in cerebral blood vessels, it is advantageous to use stents which bridge an aneurysm and screen it from the flow of blood inside the blood vessel. To enable this, providing stents with a covering is known; it occludes the cells of the stent and thus prevents a flow of blood into an aneurysm. Coverings of this type are often produced from textile materials. In combination with the stent structure, however, this results in a relatively thick-walled stent, whereupon again, the compressibility of the stent is compromised. Thus, the covering limits compression to a small cross sectional diameter, which in turn hinders delivery of the stent to small cerebral blood vessels. The Applicant's document EP 2 946 750 B1 tackles the problem of the compressibility of a stent with a textile covering by producing fibrous strands of the textile material from loosely ordered individual filaments. The prior art discloses textile-like structures which are suitable for covering aneurysms. In particular, EP 2 546 394 A1 discloses a covering of this type, what is known as a graft, which has an electrospun structure. In order to obtain a particularly low porosity, a plurality of layers of this electrospun structure are overlaid. However, this results in thick walls which are a problem when delivering to small, highly tortuous blood vessels. From WO 02/49536 A2, an electrospun structure is also known which has two layers of electrospun fabric, wherein the two layers have different porosities. Here again, the walls are relatively thick and hence the compressibility of the electrospun structure is limited. EP 2 678 466 B1 concerns a stent for neurovascular applications which is covered with a nonwoven fabric. The nonwoven fabric is produced by electrospinning and comprises a plurality of layers, wherein an inner layer is impermeable to liquid and an outer layer is sponge-like in configuration. Thus, the nonwoven fabric forms a membrane with very low permeability to liquid and because of the sponge-like layer, the walls are thick, which compromises the compressibility of the stent. When treating aneurysms using a medical device with a mesh structure in a main blood vessel, so that the mesh structure lies over the neck of the aneurysm, it has proved to be advantageous for endothelial colonization to occur. In this way, the medical device becomes integrated into the blood vessel and in the end, the tissue formed by the endothelial cells can seal off the aneurysm from the main blood vessel. The disadvantage with prior art medical devices, however, is that it is difficult for the endothelial cells to form on the mesh structure, and in particular because of the size of the cells of the mesh structure, the entire mesh structure is not evenly covered or complete coverage occurs only slowly, because the tissue has to bridge a relatively large gap between two webs or wires or