This application claims priority to European Patent Application No. 23188322.4 filed on Jul. 28, 2023, the disclosure of which is hereby incorporated in its entirety by reference.
The present disclosure relates to an aortic implant (e.g., a stent graft) with a proximal anchoring layer. In one or more aspects, the proximal anchoring layer is configured to anchor the aortic implant to a landing zone within the aorta and to resist migration of the aortic implant.
Endovascular stent grafts may be used to treat abdominal aortic aneurysms. The stent graft is an implantable device made of a tube-shaped surgical graft material and an expanding (e.g., self-expanding) stent frame. The stent graft may be a straight tube or a bifurcated tube. The stent graft may be formed of a woven textile supported by a stent. The stent may be formed of nitinol. The stent graft is placed inside a patient's vasculature (e.g., blood vessel) to bridge a diseased blood vessel segment (e.g., an aneurismal, dissected, or torn blood vessel segment), thereby excluding hemodynamic pressures of blood flow from the diseased blood vessel segment.
Endovascular stent grafts may be used to treat abdominal aortic aneurysms and/or thoracic aortic aneurysms. During the endovascular procedure, the delivery and positioning of the stent graft may be guided by x-ray imaging. When properly positioned, the stent graft is anchored on a healthy segment of the aortic vessel wall, optionally with barbs on an anchoring stent. These barbs are configured to resist the migration of the stent graft. However, migration and permeation of the stent graft and microleakage may still occur, thereby increasing the risk of non-leak proof anchoring and aneurysm sac expansion.
In an embodiment, an endovascular implant is disclosed. The endovascular implant includes a proximal end, a distal end, and a body extending between the proximal and distal ends. The body includes outer and inner surfaces. The outer surface of the body includes an outer surface landing region proximate at least one of the proximal and distal ends of the body. The outer surface landing region is configured to align with one or more landing walls of one or more vessels. The body further includes an outer surface aneurysmal region configured to at least partially span one or more aneurysms of the one or more vessels. The endovascular implant also includes an anchoring layer applied to the outer surface landing region. The anchoring layer has anchors configured to anchor the endovascular implant to the one or more landing walls of the one or more vessels. The outer surface aneurysmal region does not include the anchoring layer.
The anchoring layer may be formed of an extracellular matrix layer. The extracellular matrix layer may be an artificial extracellular matrix layer. The extracellular matrix layer may be formed of an electrospun polymer material. The endovascular implant may further include an aneurysmal region layer applied to the outer surface aneurysmal region. The anchoring layer may be formed of a first material configured to promote a wound response. The aneurysmal region layer may be formed of a second material configured to promote an inflammation response (e.g., a controlled inflammatory reaction). The first material may be different than the second material.
The anchoring layer may include a prosthetic fabric having first and second surfaces. The prosthetic fabric may include first barbs extending from the first surface. The prosthetic fabric may include second barbs extending from the second surface. The first or second barbs may be the anchors referred to above. The first and/or second barbs may be formed from one or more bioresorbable polymers. The first and/or second barbs are coated with one or more natural biopolymers.
The anchoring layer may include a gripping polymeric material layer. The gripping polymeric material layer may include a base portion and protrusions extending from the base portion. The protrusions may be the anchors. The base portion may include first and second surfaces. The protrusions may extend from the first surface. The second surface may be adhesively connected to the outer surface landing region. The protrusions may form a matrix of protrusions equally or randomly spaced from each other.
Further disclosed herein is an endovascular implant that includes a proximal end, a distal end, and a body extending between the proximal and distal ends, wherein the body includes outer and inner surfaces, wherein the outer surface of the body includes an outer surface landing region proximate at least one of the proximal and distal ends of the body, wherein the outer surface landing region is configured to align with one or more landing walls of one or more vessels, wherein the body further includes an outer surface aneurysmal region configured to at least partially span one or more aneurysms of the one or more vessels, wherein the endovascular implant also includes an anchoring layer applied to the outer surface landing region, wherein the anchoring layer has anchors configured to anchor the endovascular implant to the one or more landing walls of the one or more vessels, and wherein the outer surface aneurysmal region does not include the anchoring layer.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Directional terms used herein are made with reference to the views and orientations shown in the exemplary figures. A central axis is shown in the figures and described below. Terms such as “outer” and “inner” are relative to the central axis. For example, an “outer” surface means that the surfaces faces away from the central axis, or is outboard of another “inner” surface. Terms such as “radial,” “diameter,” “circumference,” etc. also are relative to the central axis. The terms “front,” “rear,” “upper” and “lower” designate directions in the drawings to which reference is made.
Unless otherwise indicated, for the delivery system the terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to a treating clinician. “Distal” and “distally” are positions distant from or in a direction away from the clinician, and “proximal” and “proximally” are positions near or in a direction toward the clinician. For the stent-graft prosthesis, “proximal” is the portion nearer the heart by way of blood flow path while “distal” is the portion of the stent-graft further from the heart by way of blood flow path.
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description is in the context of treatment of blood vessels such as the aorta, coronary, carotid, and renal arteries, the invention may also be used in any other body passageways (e.g., aortic valves, heart ventricles, and heart walls) where it is deemed useful.
Barbs provided by an anchoring stent are configured to anchor a stent graft to a healthy segment of an aortic vessel adjacent an aneurysm. These barbs resist migration of the stent graft after deployment within the aorta. Stent grafts may also not include barbs, instead relying on radial force from self-expanding stent rings. However, in certain cases, migration of the stent graft may occur, thereby increasing the risks of an endoleak. An endoleak (e.g., a type 1 endoleak) may result in re-pressurization of the aortic aneurysm sac, thereby increasing the risk of aneurysm sac expansion, which may lead to the rupture of the aortic vessel. Insufficient sealing of the implant (e.g., stent graft) may also cause microleakage, which may impede the regression of an aneurysm sac over time. This may cause type 2 endoleaks, thereby potentially compromising the success of an initial aortic aneurysm treatment.
Stent graft migration may result from an insufficient anchoring force of the stent graft and/or the lack of adequate tissue integration into the proximal segment of the aortic vessel used as the landing zone for the stent graft. Therefore, what is needed is a stent graft having increased initial proximal anchoring force and that integrates with newly formed tissues in the landing zone by accelerating tissue ingrowth. One or more embodiments include a stent graft having an anchoring layer applied to an outer surface of the stent graft to decrease migration and to enhance tissue ingrowth, thereby providing enhanced integration between the vessel and the stent graft over time.
Anchoring layer 36 may improve the grip and/or anchoring of stent graft 30 to the vessel wall, particularly in a proximal end region where the graft contacts the vessel wall and the two regions overlap. While
Anchoring layer 36 may be formed of an extracellular matrix layer (e.g., an artificial extracellular matrix layer). The artificial extracellular matrix material may be formed by electrospinning a porous scaffold of fibers (e.g., nanofibers) of a polymeric material onto an outer surface of a stent graft proximal landing region. The artificial extracellular matrix material may be formed to mimic the surface of the aortic vessel. In one or more embodiments, the artificial extracellular matrix material has a higher surface area than the graft material of a stent graft, thereby providing enhanced friction to promote cell adhesion.
The polymeric material may be a composite of a first natural polymer and a second natural polymer different than the first natural polymer. The polymeric material may be a composite of a first natural polymer and a first synthetic polymer. The first and/or second natural polymers may be selected from the group consisting of: chitosan, collagen, gelatin, and silk. The polymeric material may be formed of a first synthetic polymer and a second synthetic polymer different than the first synthetic polymer. The synthetic polymer may be selected from the group consisting of: polycaprolactone (PCL), poly-lactide acid (PLA), poly(lactic-co-glycolic acid), trimethylene carbonate (TMC), or a combination thereof. The polymeric material may be formed from one or more crosslinked polymers. The polymeric material may be formed from one or more reinforced polymers with one or more inorganic materials.
The porous nanofiber electrospun scaffold may also include one or more biomolecules and/or biomacromolecules to enhance bioactive cues and/or to enhance the scaffolds for the cells. The biomolecules and/or biomacromolecules may have a size of any of the following values or in a range of any two of the following values: 800, 825, 850, 875, 900, 925, 950, 975, and 1,000 Daltons. The biomolecules and/or biomacromolecules may include nucleic acids, proteins, and/or carbohydrates, made from monomer units linked together.
The mean diameter of the electrospun fibers may be any of the following values or in a range of any two of the following values: 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, and 600 nanometers.
The porous nanofiber electrospun polymer scaffold may form a matrix including one or more fibers, one or more link proteins, and one or more space filling molecules. The one or more link proteins may be configured to promote protein functionalization. The one or more link proteins may include fibronectin, laminin, or a combination thereof. The one or more space filling molecules may include proteoglycans, glycosaminoglycans, or a combination thereof.
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The aneurysmal region layer may be configured to promote an inflammation response from the patient, which may be beneficial in treatment of aneurysms. The aneurysmal region layer may be formed of a material configured to promote a controlled inflammatory reaction and/or acute and foreign body response. The inflammation response may promote formation for cytokines and/or macrophages (e.g., M1 and M2 macrophages). The inflammation response may promote blood clotting and/or thrombus formation and formation and/or differentiation of smooth muscle cells. The aneurysmal region layer may promote cell adhesion. The material used for the aneurysmal region layer may be different than the material used for the anchoring layer (e.g., different extracellular matrix materials). In one or more embodiments, the anchoring layer and/or aneurysmal region layer are not applied to the inner surfaces of the stent graft. In one embodiment, the anchoring layer may be applied to the inner surface of a region of the stent graft that will form an overlapping joint with an outside surface of another stent graft (e.g., it may be applied to the inner surface of the distal end of first branch limb 40 or second branch limb 42, which will receive branch limb extensions 44 and 46).
Anchoring layers 102 and/or 104 may be formed of a prosthetic fabric including first and second surfaces where the first and/or second surfaces may include first and/or second barbs protruding from the first and/or second surfaces, respectively. The first surface may be facing the outer surface of the stent material when applied and the second surface may be facing away from the first surface. In one embodiment, only one of the surfaces includes the barbs. In another embodiment, both surfaces include the barbs.
The barbs may be formed by creating a prosthetic fabric including loops. These loops may be treated (e.g., heat treated) to form first and second barbs by cleaving a single loop.
Barbs 120 are configured to anchor to the aortic wall or an iliac at the landing zone to secure a more stable fixation, thereby resisting the sliding of the stent graft. In one or more embodiments, barbs 120 are configured to mechanically stick to the aortic wall without the adjunction of chemical or biological adhesives.
Barbs, including grip portions 124, may be formed of one or more bioresorbable polymers. The bioresorbable characteristic may refer to the material having a property to be absorbed and/or degraded by tissues or washed from an implantation site or disappear in vivo after a certain time, which may vary, for example, from a few hours to a few months, thereby leaving tissue that integrates with the stent graft. Non-limiting examples of bioresorbable polymers include polylactic acid (PLA), polycaprolactone (PCL), polydioxanone (PDO), trimethylenecarbonate (TMC), polyvinyl alcohol (PVA), polyhydroxyalkanoate (PHA), polyglycolic acid (PGA), polyalkylene glycols, such as polyethylene glycol or polypropylene glycol, polysaccharides, such as starch, dextran and/or derivatives of cellulose, oxidized polysaccharides, mucopolysaccharides, copolymers thereof, and mixtures thereof. For example, the hydrophilic macromolecular additive is a polyethylene glycol having a molar mass of 4000 Daltons (PEG 4000). The bioresorbable material may include at least one polyvinyl alcohol. The bioresorbable material may include at least one glycerol. The resorption of the grips may induce a local inflammation reaction, thereby leading to the generation of new tissues that may fill the space between a stent graft and the aortic wall.
The prosthetic fabric may be applied to an outer surface of a graft material as a sheet portion (e.g., applied as a sleeve over the outer surface by sliding the sleeve over an end of the stent graft and into position within an end region of the stent graft). A dual-sided grip prosthetic fabric material may be secured to the outer surface with the grip portions of the barbs (e.g., without the use of an adhesive). A single-sided grip prosthetic fabric may be applied through adhesive between the smooth surface (e.g., not having grips) of the prosthetic fabric and the outer surface of the graft material. The adhesive may be a thermo-adhesive polymer, e.g., polycaprolactone. The graft material and the prosthetic fabric form a two-component structure configured to promote a wound response with the vessel wall within the landing zone region (e.g., for the promotion of infrarenal and iliac fixation and sealing), or smooth muscle cell differentiation.
Prosthetic fabric may mean any fabric formed of one or more biocompatible yarns, fibers, filaments, multi-filaments, or a combination thereof, using knitting, weaving, braiding or a non-woven arrangement or assembly. The arrangement of the yarns of the prosthetic fabric defines first surface and an opposing second surface. The prosthetic fabric may include barbs that protrude from at least the first surface. These barbs may protrude from the first surface substantially perpendicular to the plane of the first surface or alternatively along one more planes inclined relative to the plane of the first surface. The barbs are configured to fasten and anchor to a vessel wall within a landing zone region.
The barbs may be formed from yarns, e.g., hot-melt monofilament yarns directly resulting from an arrangement of yarns forming the fabric. The barbs may be formed from monofilament yarns made of polylactic acid.
In alternative embodiments, the barbs of the prosthetic fabric may be any hook produced from any biocompatible material, attached to the arrangement of yarns forming the fabric, whether these hooks were incorporated into said fabric during the manufacture (braiding, knitting, weaving, etc.) of the arrangement of yarns or were added thereafter.
In one or more embodiments, the barbs have the shape of a rod surmounted by a head. The average size of the head of the barbs may be any of the following values or in a range of any two of the following values: 100, 125, 150, 175, 200, 225, 250, 275, and 300 μm.
The yarns, or fibers or filaments and/or multi-filaments forming the arrangement of yarns of the fabric of one or more embodiments may be produced from any biodegradable or non-biodegradable biocompatible material, or combination thereof. The biodegradable material suitable for the yarns of the fabric may be chosen from polylactic acid (PLA), polyglycolic acid (PGA), oxidized cellulose, polycaprolactone (PCL), polydioxanone (PDO), trimethylene carbonate (TMC), polyvinyl alcohol (PVA), polyhydroxy-alkanoates (PHAs), polyamides, polyethers, copolymers of these compounds and mixtures thereof. The non-biodegradable materials suitable for the yarns of the fabric may be chosen from polyethylene terephthalate (PET), polyamides, aramids, expanded polytetrafluoroethylene, polyurethane, polyvinylidene difluoride (PVDF), polybutylesters, polyetheretherketone (PEEK), polyolefins (such as polyethylene or polypropylene), copper alloys, silver alloys, platinum, medical grades of steel such as medical grade stainless steel, and combinations thereof.
In embodiments where one surface has barbs, the other surface may be at least partially covered with an impenetrable layer (e.g., a microporous layer) produced from a solution of bioresorbable material. The bioresorbable material may be formed of a natural biological polymer material (e.g., collagen, gelatin, fibrin, fibrinogen, elastin, keratin, albumin, hydroxypropyl methyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, and mixtures thereof).
The barbs may also be coated with one or more natural biopolymers (e.g., collagens or hyaluronic acid) to reinforce new tissue formation. Alternatively, the barbs may be treated (e.g., with plasma surface technologies) to enhance the wettability properties (e.g., increase the hydrophobic properties at the surface) and/or to impart additional anchoring properties (e.g., the grafting of acrylate moieties by plasma surface technologies).
The prosthetic fabric, including the barbs may be treated with an antimicrobial agent. Non-limiting examples of antimicrobial agents include quaternary amines (e.g., triclosan also known under the name 2,4,4′-trichloro-2′-hydroxydiphenyl ether, polyhexamethylene biguanide (PHMB), or diallyldimethylammonium chloride also known as DADMAC, chlorhexidine and its salts (e.g., chlorhexidine acetate, chlorhexidine gluconate, chlorhexidine hydrochloride and chlorhexidine sulphate), silver and its salts (e.g., silver acetate, silver benzoate, silver carbonate, silver citrate, silver iodate, silver iodide, silver lactate, silver laurate, silver nitrate, silver oxide, silver palmitate, silver protein complex and silver sulphadiazine), polymyxin, tetracycline, aminoglycosides, such as tobramycin and gentamicin, rifampicin, bacitracin, neomycin, chloramphenicol, miconazole, quinolones such as oxolinic acid, norfloxacin, nalidixic acid, pefloxacin, enoxacin and ciprofloxacin, penicillins such as oxacillin and pipracil, nonoxynol-9, fusidic acid, cephalosporines, and combinations thereof. Antimicrobial proteins and peptides (e.g., bovine lactoferrin and lactoferricine B) may also be suitable as a bioactive agent according to one or more embodiments.
In embodiments where both the first and second surfaces have barbs, a warp knitting machine including a needle bed including four guide bars (e.g., first, second, third, and fourth guidebars) may be used to form the dual-sided grip prosthetic fabric material, operating together and each repeating a knitting pattern defining the evolution of the yarns.
Non-limiting examples of fabrics with barbs suitable for use in one or more embodiments include Parietex® Progrip or Parietene® Progrip.
In another embodiment, a gripping polymeric material layer may be used as the anchoring layer.
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The protrusions (e.g., protrusions 154 and 208) may have a profile or dimension (e.g., diameter) of any of the following values or in a range of any two of the following values: 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 μm. The spacing between pairs of protrusions within a matrix of protrusions may independently selected be any of the following values or in a range of any two of the following values: 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 μm. The spacing and location of the protrusions may be regularly repeating or random. The base portion (e.g., base portion 152 or 202) may have a thickness of a thin film, e.g., any of the following values or in a range of any two of the following values: 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50. The gripping polymeric material may be formed of a bioresorbable material (e.g., the example materials identified above). The gripping polymeric material may be formed using a molding process (e.g., injection molding or thermal pressure molding).
The gripping polymeric material layer may be applied to an outer surface of a graft material as a sheet portion (e.g., applied as a sleeve over the other surface by sliding the sleeve over an end of the stent graft and into position within an end region of the stent graft). A dual-sided protrusion material may be secured to the outer surface with the protrusions (e.g., without the use of an adhesive). A single-sided protrusion material may be applied through adhesive between the smooth surface (e.g., not having protrusions) and the outer surface of the graft material. The adhesive may be a thermo-adhesive polymer, e.g., polycaprolactone. The graft material and the gripping polymeric material layer form a two-component structure configured to promote a wound response with the vessel wall within the landing zone region (e.g., for the promotion of infrarenal and iliac fixation and sealing).
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.
Number | Date | Country | Kind |
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23188322.4 | Jul 2023 | EP | regional |