WO2014013444A2

WO2014013444A2 - Endoluminal vascular prostheses for small vessels

Info

Publication number: WO2014013444A2
Application number: PCT/IB2013/055868
Authority: WO
Inventors: Guro BJØRNSTAD; George L. De Goicoechea; David TANNÉ
Original assignee: St George Medical Inc
Priority date: 2012-07-17
Filing date: 2013-07-17
Publication date: 2014-01-23
Also published as: WO2014013444A3; FR2993451A1

Abstract

The invention relates to a vascular prosthesis intended for being inserted in a vessel having stenosis or a constriction. In order to prevent early restenosis and late thrombosis, such a prosthesis comprises a substantially tubular main member consisting of a non-absorbable lattice (11) engaging with the bio-absorbable means (12) thereof, comprising one or more medicinal agents and a biocompatible monomer or polymer stimulating cell growth around said lattice.

Description

Endoluminal vascular prosthesis for small vessels

The invention relates to an endoluminal vascular prosthesis, also called an endovascular prosthesis or more generally to a device intended to be introduced into a vessel with a stenosis or narrowing of the vessel lumen. The installation of such an endovascular prosthesis makes it possible to recover a satisfactory arterial lumen conducive to normal circulation within said vessel. The invention relates more particularly but not limited to a prosthesis for small veins or arteries, coronary arteries or small vessels of the lower or upper limbs or even the carotids and cerebral vessels.

As described by way of example Figures la and lb, a stenosis generally stems from an accumulation of fat deposits on the inner wall or intima 3 of a vessel 1 thus forming one or more plates 2. These deposits can consist of cholesterol, calcium or other blood-borne substances. The formation of said plates may eventually close vessels, including small arteries such as coronary arteries, making them rigid and irregular. To treat this pathology, the interventional cardiologist may use a transluminal angioplasty to introduce a balloon, which when inflated, pushes out the plates formed against the intima. The balloon is subsequently removed and the arterial lumen 4 is restored. However, the effect can be short-lived. To prolong the latter, a therapeutic gesture may consist in placing an endovascular prosthesis or a stent in the form of a flexible metal cylinder whose mesh provides, like a scaffold, a reactive force to collapse. of the inner wall of the vessel. At the level of the lesion, the stent remains present in the vessel in the long term. It thus keeps the vessel open enough for the blood to circulate normally.

There are different types of endovascular prosthesis. The oldest consist of a mesh or bare metal mesh (stent). The wire mesh is directly applied in contact with the vessel wall. More recent, as exemplified by US 6,010,530, prostheses may consist of a wire mesh - such as a wire constrained to materialize zigzags - which optionally includes a polymer type coating. The stent (for example nitinol-based) can be self-expanding when placed with a catheter and a retractable sheath. It can alternatively be deployed using a balloon. In the latter case, the stent is crimped onto said balloon as the interventional cardiologist inflates within the vessel to repel the plaques and restore the arterial lumen. The balloon is then deflated and removed. Once the plates are pushed against the inner wall of the vessel, the stent is a scaffolding supporting the wall of said vessel. The stent remains in the vessel to keep it open. The therapeutic effects of stent placement are relatively long-lasting thanks to the scaffolding provided by said stent.

However, it has been found that the body can react following the stent placement by rejecting this foreign body. The metallic structure of the stent seems to have a major role in this reaction, which can result in restenosis, ie a new formation of stent narrowing at the level of the stent limiting the arterial lumen of the vessel. This phenomenon can appear within 6 months to 2 years depending on the patient, his lifestyle or diet, etc. The prevalence at 6 months is estimated at 20 to 30% of patients who received a bare coronary stent, compared to 30 to 60% of patients who had balloon angioplasty alone. To delay the occurrence of restenosis, US 6,010,530 teaches that the coating (if any) of the endovascular prosthesis may be impregnated with a drug substance or agent - for example Rapamycin or Paclitaxel. - Which is released gradually into the body after the installation of the stent in a vessel. This substance may have a particular effect or a plurality of effects, among which we may mention anti-inflammatory, antimicrobial, antibacterial, anti-thrombotic or anticoagulant effects. In particular, it makes it possible to limit the formation of thrombosis and / or the excessive proliferation of smooth muscle cells thus preventing early restenosis. As a variant, the metal mesh may be directly covered with a substance equivalent to that impregnated with the coating of the preceding stent or with a plurality of substances the combined effects of which slow the occurrence of restenosis. Such prostheses having an additional assimilable substance are commonly referred to as "drug-eluting stents". Thus, restenosis can be delayed for several years compared to a bare stent. The prevalence at 6 months is then estimated between 3 and 20% of patients who received a drug-eluting coronary stent according to the types of stent and drug agents used. Although having a remarkable progress, such endovascular prostheses nevertheless raise some disadvantages. An endovascular prosthesis with a coated stent does not promote "uptake" of the stent by the treated vessel. Once the effect induced by the substance or substances fades, the coating, which is permanent, contributes to the "rejection" effect of the endovascular prosthesis.

US 6,010,530 teaches that to limit this disadvantage, the coating may have holes or be made using a porous material. Thus, endothelial cells can infiltrate into said wall and form a new intima which, like a filter, allows blood to feed the vessel wall again.

Other known embodiments of drug-eluting stents use a non-coated prosthesis. The mesh is thus directly applied against the inner wall of the treated vessel. In order for the prosthesis to prevent early restenosis, the substances making it possible to constitute a drug-eluting stent are directly deposited in successive layers on the metal mesh of the stent. Alternatively, the substance or substances may be deposited in a single layer by spraying or dipping. Thus, in addition to its scaffolding function, this metal mesh fulfills the role of "substance carrier". In order that a sufficient quantity of substances can be diluted within the treated vessel, it is necessary that the mesh of the stent is particularly dense to convey said substances. This high metal density comes at the expense of the flexibility and flexibility of the whole (very useful depending on the tortuosity of the vessel treated), the cost of the endovascular prosthesis and the desired effect to prevent a restenosis linked to an excessive presence of metal compounds. After the dilution of the substances, a high density of the mesh can thus reinforce a risk of restenosis requiring a new therapeutic intervention.

The use of drug-eluting stents may further promote late thrombosis. Indeed, while a bare metal stent does not cause this secondary complication following the implantation of the wire mesh because of a sufficient endothelization, recent drug-eluting stents slow endothelization of the wire mesh. Thus the use of such stents leads to a deleterious prolongation of post-operative oral antiplatelet therapy to prevent any risk of thrombosis in the long term. By using broad-spectrum drug agents such as Rapamycin or Paclitaxel, current stents prevent the proliferation of smooth muscle cells and reduce the risk of restenosis, but also prevent proliferation and colonization. coating or wire mesh by the endothelial cells. Thus, even in the long term, certain portions of the lattice remain in direct contact with the blood, which potentially induces thrombus formation, if the blood is not anticoagulated sufficiently.

The invention makes it possible to meet all the disadvantages raised by the known solutions. The main object of the invention is to provide a prosthesis with minimal or sufficient radial force or crush response sufficient to permanently maintain a nominal arterial lumen while preventing the risk of short and long term restenosis and thrombosis. long term. The invention to improve the tolerance of the stent by the body through a particularly innovative design and the presence of bio-absorbable means primarily but non-limitingly transporting substances with virtues conducive to cell development to form a new intima imprisoning the prosthesis . These substances may have a particular effect or a plurality of effects, among which we can mention anti-inflammatory, antimicrobial, antibacterial, anti-thrombotic or anticoagulant effects or promoting adhesion and proliferation of endothelial cells.

Among the many advantages provided by the invention, we can mention that the invention allows:

to promote the healing response of the vascular wall;

- to improve the growth and homogeneity of the intima recreated after the prosthesis has been placed and to promote controlled cell growth to limit the risk of late thrombosis;

to slow down or even prevent restenosis after placement of an endovascular prosthesis and thus to reduce the occurrences of therapeutic gestures to maintain a satisfactory and perennial arterial lumen in a treated vessel;

to facilitate tolerance by organizing prostheses by the optimized and minimal presence of metallic material and bioabsorbable means; For this purpose, firstly an endovascular prosthesis is provided comprising a substantially tubular non-resorbable mesh and bioabsorbable means cooperating with said non-resorbable mesh, said bioabsorbable means comprising a monomer or polymer and one or more medicinal agents stimulating cell growth around said nonabsorbable mesh. To prevent early restenosis and facilitate the assembly of such a prosthesis, said bioabsorbable means consist of a resorbable mesh substantially tubular and symmetrical to the non-resorbable mesh - with respect to a sectional plane of said non-resorbable mesh - to points of mutual cooperation between the two trellises.

Among several advantageous embodiments, the non-resorbable mesh and the bioabsorbable mesh may advantageously consist respectively of a structure forming a plurality of rings respectively comprising vertices connected in pairs by substantially rectilinear uprights and comprising a flexible portion having a or several curvatures.

Such a flexible portion may advantageously advantageously describe an ^A S 'or a ^Λ Ζ'.

To preserve the flexibility of the trellis, two adjacent crowns of the same trellis may advantageously cooperate via a flexible connector connecting two vertices respectively of said crowns.

Such a flexible connector can advantageously advantageously describe a double ^A S '.

To promote the flow of blood in contact with the prosthesis and to reduce recirculation and high shear zones, when the trellises respectively describe a structure forming a plurality of crowns, the amounts of said crowns and / or the vertices and / or the connectors may have a substantially trapezoidal section whose inner base is less than the outer base.

According to this variant, the cutting angles of the section of the amounts of the crowns and / or the tops and / or connectors may however be different.

To allow the introduction of the prosthesis via a catheter and its automatic expansion or assisted by a balloon, the non-resorbable and bioabsorbable meshes advantageously mutually cooperate substantially at the non-rectilinear flexible portions of the amounts respectively connecting two vertices of a same crown.

To make the assembly of the prosthesis more reliable, the flexible portion of an upright of the bioabsorbable structure may comprise a recess for partially accommodating the flexible portion of an amount of the non-resorbable mesh.

To prevent restenosis and late thrombosis, bioabsorbable means may be impregnated with one or more drug agents of a group consisting of anti-inflammatory, antiproliferative, antiplatelet, anticoagulant, anti-thrombotic or adhesion promoting agents. , growth and maturation of endothelial cells.

In particular, to prevent initial inflammation and acute thrombosis, a prosthesis according to the invention may further comprise a permanent coating or a bioabsorbable polymer which covers all or part of the assembly consisting of non-absorbable and bio-absorbent meshes. absorbable.

According to this variant, the coating may advantageously be arranged to degrade completely in a few weeks to a few months by emitting substances having a particular effect or a plurality of effects, including anti-inflammatory, antiplatelet, anticoagulant, anti-thrombotic and antiproliferative effects.

Such a coating may advantageously consist of a lipid or lipid layers to target and attract endothelial cells or promote the development of such cells around lattices.

To facilitate the therapeutic gesture and control the positioning of a prosthesis according to the invention in the vessel, said prosthesis may comprise radiopaque means located at the ends of the non-resorbable mesh.

In a preferred configuration, a prosthesis may comprise a quantity of bioabsorbable means substantially equivalent to that of the non-resorbable mesh.

Other features and advantages will appear more clearly on reading the following description and examining the accompanying figures, among which:

FIGS. 1a and 1b (already described) show a partial view of the vascular system of a patient with arterial stenosis;

FIG. 2 describes a first prosthesis according to the invention;

FIGS. 3a and 3b describe a partial view of the vascular system of a patient presenting with an arterial stenosis immediately after the application of a prosthesis according to the invention;

FIGS. 3c and 3d describe a partial view of the vascular system of a patient presenting an arterial stenosis after the application of a prosthesis according to the invention once the bioabsorbable means are completely degraded several months after implantation of the prosthesis;

Figure 4 describes the (non-absorbable) wire mesh of a second prosthesis according to the invention;

FIGS. 4A and 4B more precisely respectively describe two rings of the (non-resorbable) wire mesh presented in connection with FIG. 4;

Figures 5 and 5A describe a section advantageously arranged with an amount of a crown of a prosthesis according to Figure 4;

FIGS. 6 and 6A respectively disclose global and partial views of a prosthesis according to the invention having bioabsorbable means crimped on a (non-resorbable) wire mesh as described with reference to FIG. presents a first preferred embodiment of an endovascular prosthesis 10 according to the invention when it is deployed.

This comprises a main member or substantially tubular stent consisting of a non-resorbable or permanent mesh, preferably in the form of a continuous wire 11 and folded into a configuration allowing the contraction (or crimping of the limb if the deployment of this denier is assisted by balloon) and the expansion of the prosthesis. A such lattice is preferably made based on cobalt chromium or nitinol. As shown in Figure 2, the lattice has a zigzag or chisel configuration. This configuration is particularly advantageous because, when the prosthesis is deployed, scissors or crowns materialized (e) s by the wire mesh prevent excessive growth in cells in contact with said mesh. The invention would however be limited to this preferred configuration.

The invention provides that the stent can be self expanding ^¬ when the latter is released from a sheath of a catheter carrying the or alternatively be expanded using a balloon. According to the embodiment chosen, the mesh is designed according to well-known techniques to ensure such automatic deployment or assisted by a balloon.

The density of the mesh is further determined to deliver, after deployment, a radial force or a crush-responsive force sufficient to maintain an open vessel. The function of the wire mesh (non-resorbable or permanent) is reduced to a scaffolding role to sufficiently support the inner wall of the treated vessel.

To limit the risk of occurrence of restenosis, the invention provides that the metal mesh (non-absorbable) is reduced to its simplest expression - simply sufficient to allow it to maintain the vessel permanently open. In addition, to prevent the risk of restenosis following the placement of a prosthesis according to the invention, bioabsorbable means 12 cooperate with said wire mesh and permanent 11. These means can be preferably made in the form of one or more polymers having one or several medicinal agents. Thus, as indicated by way of example in FIG. 2, one or more bioabsorbable fibers 12 is (are) interlaced with the wire mesh 11. The fibers 12 appear in fine lines in FIG. lattice 11 shown in thick lines. The carriers are - non-exhaustively - an anticoagulant to limit clot formation or a monomer whose role is to catalyze or promote cell growth of tissues in contact with the prosthesis. The tissues can thus interfere within the mesh to constitute after a few weeks or months a new intima imprisoning the mesh metal. The latter - in addition to its role of scaffolding provides a role of trellis. The function of the agents is temporary. The means carrying the agents are therefore intended to be bioabsorbable. Several weeks or months after the insertion of the endovascular prosthesis, said means 12 are completely resorbed. Only remains the non-resorbable metal mesh 11 which continues its role of scaffolding and trellis. The density of foreign body remaining present can thus be reduced in view of the prior art. Different configurations of bioabsorbable means are possible. For example, fibers 12 may be interwoven cooperating with the mesh 11 to diffuse the agents along the tubular member in a homogeneous and equitably distributed manner. Said medicinal agents and / or biocompatible monomer (s) can thus be regularly distributed along the wire mesh 11 (mainly on one of the inner or outer parts of the mesh or equitably on said parts). For a self-expanding prosthesis whose metal stent is calibrated to exert a determined radial force, the density of biological means Absorbable can be adjusted to determine the amount and dynamics of elution of the carriers regardless of the density of metal compounds. The invention thus reduces the risk of restenosis and promotes the assimilation of the prosthesis by organizing the patient.

According to a preferred embodiment, a prosthesis according to the invention is substantially composed (before its application within a vessel) of 50% of permanent elements (preferably metallic) 11 and 50% of bioabsorbable means 12. Other proportions could be envisaged according to the desire to strengthen or reduce the radial force exerted by the mesh 11 or the degree and distribution of the drug agents carried by the bioabsorbable means 12.

Figures 3a and 3b depict a vessel 1 as illustrated in connection with Figures 1a or 1b. This has a stenosis in the form of a plate 2. After having dilated the vessel and pushed out the plate 2, a prosthesis 10 according to the invention has been applied. Whether its expansion is automatic or assisted by inflating a balloon, the metallic mesh 11 bears against the intimal 3 of the vessel and exerts either a radial force for a self-expanding stent or a resistance to pressure. crushing for a balloon expandable stent against said intima. This force or resistance is sufficient to keep the vessel open so that the arterial lumen 4 of the latter is satisfactory. Bioabsorbable means 12 cooperating with the mesh 11 appear in fine lines with regard to the wire mesh 11 shown in thick lines. The presence of anticoagulants carried by said means 12 or other medicinal substances prevent the risk of restenosis and acute or late thrombosis by promoting the healing response of the vascular wall.

Figures 3c and 3d describe the same vessel, a few months to a few years after the application of the prosthesis 10. The bioabsorbable means are resorbed. The presence of a monomer carried by the bioabsorbable means 12 (present in FIGS. 3a and 3b), a monomer promoting cell growth of the tissues in contact with the tubular member of the prosthesis, has favored the creation of a new intimal 3 imprisoning the mesh 11 represented by transparency in FIG. 3c in dotted lines. It continues its function of scaffolding but the new intima 3 'perfectly irrigated and having a smooth surface facilitates the blood circulation and prevents any risk of late thrombosis. The arterial lumen 4 is thus durably preserved.

The invention provides a second embodiment of a prosthesis which allows in particular to reduce the density of the non-resorbable mesh (preferably metal or ceramic-based) while preserving the flexibility of the assembly. FIG. 4 thus describes a non-resorbable metallic mesh, either made preferentially based on a wire, but on the basis of a substantially tubular structure 11 that has been - previously - cut out (to be perforated) by example using a LASER beam or any other technique. The cut or molded structure is advantageously based on cobalt-chromium or nitinol or even stainless steel, ceramic (s). In connection with the example illustrated by Figure 4, the mesh 11 comprises one or more rings 110A, 110B and HOC. In the same way as a woven wire mesh described in connection with Figure 2, this technique allows for a wire mesh 11 whose configuration provides a good contraction capacity, a crimp on a balloon or an automatic expansion or assisted by the balloon of the main limb of the prosthesis. To reduce the metal and permanent density, one can reduce the number of crowns by "stretching" them. A ring (for example one of the rings 110A or 110B) has vertices connected in pairs by substantially rectilinear amounts. Thus, in FIG. 4, two vertices 111A and 114A connected by an amount 112A can be distinguished. To better distinguish the different elements, FIG. 4A shows a partial enlargement of the mesh 11. This view corresponds to the portion symbolized by the circle A represented in FIG. 4. FIG. 4A thus describes the apex 111A from which two substantially rectilinear amounts 112A start. and 113A. To maintain good flexibility and maintain the ability of the prosthesis to conform to the anatomy of a patient, the invention provides that said uprights comprise a non-rectilinear portion. Thus the amount 112A comprises two substantially rectilinear portions 112Ax and 112Az and a central portion 112Ay having one or more curvatures. In connection with FIGS. 4 and 4A, this portion advantageously and substantially describes an ^A S 'or a "Z" in the plane of the surface of the lattice (at the radius of curvature of the tubular structure 11 near). Other curvatures could be provided at the portion 112Ay. Likewise, other positions of the portion 112Ay relating to the portions 112Ax and 112Az and other ratios of lengths between these different Portions can be provided. It suffices that said configuration of the portions 112Ax, 112Ay and 112Az offers the desired flexibility and conformability. In addition to flexibility recovered, the configuration of such a lattice reduces the "spring" effect that is to say the "springback" and "shortening" of the stent particularly sensitive after the expansion of the prosthesis. The mesh 11 described in connection with FIGS. 4 and 4A thus comprises the uprights 112A and 113A starting from the apex 111A having a non-rectilinear portion 112Ay. Such amounts could alternatively comprise a plurality of portions having one or more curvatures instead of one. This variant allows for example to further stretch the crowns by lengthening the length of the amounts of a crown.

In the same way as for FIG. 4A, FIG. 4B illustrates a second ring 110B of the lattice 11 described in connection with FIG. 4. This enlargement (corresponding to the portion of said lattice 11 surrounded by the oval B in FIG. 4) shows that the crown 110B comprises in particular two vertices 111B and 114B connected by a substantially rectilinear amount 112B. This amount comprises a substantially central portion 112By which has - like the amount 112A of the crown 110A - one or more curvatures. It is the same for a second amount 113A connecting the top 112B to a third crown of the crown 110B.

To ensure the connection between the various crowns while maintaining the flexibility of the mesh 11 and the conformability of the prosthesis to a pathological vessel, the distal peaks of a crown can be connected respectively to the proximal vertices of a neighboring ring by means of connectors. flexible. So, in connection with the embodiment shown in Figure 4B, a flexible connector 132 connects the vertex 111B of the ring 110B to one of the apices of the adjacent ring 110A. It is the same for the top 111C of the adjacent crown HOC which is connected to a crown of the crown 110B by the flexible connector 133. FIG. 4A also illustrates a connector 131 connecting the crown 110A (the crown 111A) to a neighboring ring .

According to a particularly advantageous embodiment, such a connector can describe a double ^A S '. Other forms of connection could however be envisaged to connect the crowns of the same lattice 11.

In a preferred manner, the flexible connector links two neighboring crown peaks (vertex-vertex configuration) but other junctions could also be envisaged such as a summit-up-valley-summit junction (the valley being the inner side of the vertex). , valley-valley or any other combination or place of junction between two neighboring crowns by a flexible connector.

The use of a lattice made from a tubular structure cut or molded allows to promote the cellular colonization of the wire mesh. Indeed, according to a preferred embodiment, the trellis (mainly the amounts of the crowns) may have a trapezoidal section so that the base Be of the outer wall intended to be in contact with the vascular wall of the vessel (or external base) an amount of the mesh is greater than the base Bi of the inner wall of said amount (or internal base) intended to be in contact with the blood. This result can for example be obtained by cutting the metal tubular structure by a beam in a non-normal manner. the outer surface of the tube. An inclination of the firing angle of the LASER beam (ALPHA angle) makes it possible to remove additional material 112Ba at a normal normal cut at the surface to form an amount 112B of substantially trapezoidal cross-section as described by way of example in FIG. 5. Similarly the other side of the amount can be cut with a BETA angle and a withdrawal of material 112Bb, equal or not to the angle ALPHA. It is therefore possible to machine the structure so that the amounts are thinner towards the central axis of the structure. While Figure 5 shows an embodiment of the section of a profiled post after cutting LASER (angles ALPHA and BETA equal), Figure 5a describes this same section once polished by a preferred technique of electro-polishing. The sharp edges are smoothed and the thickness of material removed is adjustable during the polishing operation. This possibility can be applied to single amounts or to the entire trellis. This configuration makes it particularly advantageous to reduce, in particular, the local stasis or recirculation zones around the uprights by reducing the disturbances created by the trellis on the flow of blood to the wall of the vessel. As a result, the risk of thrombosis formation is reduced after application of the prosthesis. This configuration further promotes the colonization of endothelial cells by reducing the shear stresses generated by the fluid against the wall of the prosthesis. Adhesion and growth of endothelial cells is thus favored, eventually producing a better recovery of the lattice by the new intima and thus a reduction in the risk of late thrombosis. The mesh 11 of a prosthesis made according to this second embodiment - illustrated in FIGS. 4, 4A or 4B) cooperates with bio-absorbable means such as, for example, a polymer in the same way as the prosthesis described in connection with FIG. 2. The preferably metal tubular structure 11 can thus receive bioabsorbable means which consist of polymer fibers interwoven with said wire mesh.

Alternatively, the invention provides that said bioabsorbable means can be obtained by molding or cutting a substantially tubular structure whose configuration is close to or identical to that of the wire mesh. According to this variant, a second substantially resorbable tubular structure 12 (based on a polymer or a biodegradable or biosorbable ceramic) is thus formed of a plurality of crowns respectively comprising vertices connected in pairs by substantially rectilinear and comprising at least one flexible portion having one or more curvatures. Figures 6 and 6A illustrate this particularly advantageous variant.

In the same way as the variant described in connection with FIG. 2, the bioabsorbable means may be impregnated with one or more medicinal agents. To prevent restenosis and late thrombosis, the drug agent (s) of said bioabsorbable means are advantageously one or more agents of a group consisting of anti-inflammatory, antiproliferative, antiplatelet, anti-coagulant, anti-thrombotic or anti-inflammatory agents. adhesion, growth and maturation of endothelial cells.

FIG. 6 shows a metal mesh 11 around which bioabsorbable means 12 are applied. two elements 11 and 12 are mutually arranged to cooperate perfectly for example during a crimping operation means 11 and 12 on a balloon or contraction in a sheath of a catheter prior to the application of the prosthesis within a pathological vessel. According to Figure 6, the two lattices (metal 11 for one and resorbable 12 for the second) are similar and symmetrical (or inverted). The term "symmetrical lattices" means two distinct tubular structures whose respective sections are of substantially equal diameters and thickness and whose respective lattice configurations are symmetrical with respect to a sectional plane of the tubular structures or, more generally, of the main member. the prosthesis after assembly. When a tubular structure encases the second, the geometries or the arrangement of the structures 11 and 12 induce in particular a symmetry of the flexible portions with respect to points of mutual cooperation of the two structures so that the two structures 11 and 12 cooperate essentially with each other. level of non-rectilinear flexible portions of the crown amounts. In connection with FIG. 6, the two lattices or tubular structures have lattice configurations which are identical and symmetrical with respect to one another.

As a variant, the resorbable (or bioabsorbable) mesh 12 may retain only the same symmetry of the flexible portions at the points of mutual cooperation and describe amounts or peaks of curvature of different lengths and / or shapes with respect to the mesh 11 .

Alternatively, resorbable mesh 12 may consist of one or more trellises or structures composed of one or more types of resorbable materials. of equal or different resorption duration and containing one or more anti-inflammatory, antiproliferative, antiplatelet, anticoagulant, anti-thrombotic or promoting the adhesion, growth and maturation of endothelial cells.

FIG. 6A is an enlargement of a portion A of the prosthesis illustrated in FIG. 6. Among the rings 120A, 120B of the polymer mesh 12 and the rings 110A, 110B of the wire mesh 11, FIG. 6A describes a particularly advantageous mutual arrangement. . The ring 110A of the mesh 11 has a top 111A from which a substantially rectilinear upright 112A which however comprises at least one non-rectilinear portion 112Ay. This ring 110A cooperates with the ring 120A of the polymer mesh 12 mainly at the 123Ay portion of the amount 123A of said ring 120A. This portion 123Ay has secant curvatures with regard to the curvatures of the portion 112Ay. The respective portions 123Ay and 112Ay of the substantially rectilinear amounts 123A and 112A, substantially describe an ^A S 'or ^Λ Ζ' respectively symmetrical or inverted. The superposition of said non-rectilinear portions describes an open ^Λ Χ 'or alpha whose intersection constitutes a point of support and pivot. According to an advantageous embodiment, the 123Ay portion may comprise a cavity 123Ayr or a 123Ayr arranged for - that audit point of contact - the amount 123A enchased the amount 112A. The holding of all, the crimping and expansion of the two lattices can be improved. As a variant or in addition, an outer recess on a flexible portion 112Ay or an amount 112A of the wire mesh may be considered to partially embed an amount of the polymer mesh. The mutual arrangement of lattices 11 and 12 is particularly advantageous because it does not interfere with the expansion of the prosthesis during its implantation in the vessel and provides it with great flexibility while minimizing the effects "springback" and "shortening". The invention however can not be limited - according to this second embodiment - to this preferred example of mutual arrangement. Thus a variant may consist of a bioabsorbable means 12 identical to that of Figure 6 and which covers a thin thickness of the wire mesh 11 on its outer surface. Thus, no metal part is in contact with the vessel wall, which can reduce the inflammatory reaction during the first post-operative time, depending on the type of drug impregnated in said bioabsorbable means.

To facilitate the therapeutic gesture, the invention provides that radio-opaque markers can be positioned on the main member of the prosthesis regardless of the structure of the prosthesis according to the invention braided or tubular trellis). Preferably, such markers are positioned at the ends of the non-resorbable mesh. By way of example and with reference to FIG. 2, markers 13 and 14 may be positioned at the extremities of the limb. The practitioner can thus control his gesture positioning perfectly - using a catheter carrying the prosthesis - the latter prior to its automatic expansion or assisted.

The invention further provides that an abluminal coating preferably or over the entire prosthesis may cover all or part of the assembly constituted by the non-resorbable metal mesh and the lattice bioabsorbable after the latter have been assembled or prior thereto.

In the case where the lattice 12 consists of one or more lattices or structures composed of one or more types of resorbable materials of equal or different resorption duration and containing one or more anti-inflammatory, antiproliferative, antiplatelet, anticoagulant agents, anti-thrombotic or promoting the adhesion, growth and maturation of endothelial cells, the coating can be applied to either the mesh or the lattice individually before assembly, or on the complete or partial assembly of the lattices. The coating can be applied to the whole or the inner surface or the outer surface of a mesh. Such a coating can additionally or alternatively be applied to a non-resorbable mesh.

Said coating is in a preferred embodiment a bioabsorbable polymer which degrades completely in a few weeks to a few months. To reduce the initial inflammation and acute thrombosis, this coating may contain substances having a particular effect or a plurality of effects, among which we can mention anti ^¬ inflammatory, antiplatelet, anticoagulant, antithrombotic and antiproliferative.

According to a preferred embodiment, the invention further provides that the coating may consist of a lipid or a layer of lipids and / or any other molecules found naturally in the human body or even synthetic. The function of this lipid (or equivalent) is to target and attract endothelial cells or to promote the development of such cells around or lattice on all or part of the set of 11 and resorbable metal mesh (s) 12. One or more lipids or layers of lipids (or equivalent molecules) can thus be applied permanently to said lattice or lattices to target and attract endothelial cells which cover the short-term and long-term enough the lattice or noticeable thus any negative inflammatory reaction or rejection of the human body against the prosthesis.

The invention has been described in a preferred manner in connection with an endovascular prosthesis for small vessels such as small veins or arteries, coronary arteries or veins or arteries of the lower limbs (femoral, tibial, popliteal arteries) or upper limbs or even the carotids and cerebral vessels. The invention applies naturally to any other endovascular prosthesis having a persistent or non-resorbable metallic mesh cooperating with bioabsorbable means.

Claims

An endovascular prosthesis (10) comprising a substantially tubular non-resorbable mesh (11) and bioabsorbable means (12) cooperating with said non-resorbable mesh, said bioabsorbable means comprising a monomer or polymer and one or more stimulating drug agents a cell growth around said wire mesh, the prosthesis being characterized in that said bioabsorbable means (12) consist of a resorbable mesh substantially tubular and symmetrical to the non-resorbable lattice - with respect to a sectional plane of the non-resorbable mesh - points of mutual cooperation of the two trellises.

Prosthesis according to the preceding claim, wherein the non-resorbable mesh (11) and the bioabsorbable mesh (12) respectively consist of a structure forming a plurality of rings (110A, 110B, HOC, 120A, 120B) respectively comprising vertices (111A, 114A, 111B, 114B, 121A) connected in pairs by substantially rectilinear uprights (112A, 113A, 112B, 113B, 122A, 123A) and having a flexible portion (112Ay, 112By, 123Ay) having one or more curvatures .

Prosthesis according to the preceding claim, wherein the flexible portion (112Ay, 112By, 123Ay) substantially describes a ^Λ 3 'or ^Λ Ζ'.

Prosthesis according to claims 2 or 3, for which two adjacent crowns of the same lattice cooperate via a flexible connector (131, 132, 133, 141) connecting two vertices respectively said crowns. 5. Prosthesis according to the preceding claim, wherein the flexible connector (131, 141) substantially describes a double ^A S '.

6. Prosthesis according to any one of claims 2 to 5, wherein the amounts of the crowns and / or the tops and / or connectors have a substantially trapezoidal section whose inner base (Bi) is lower than the outer base (Be). ). 7. Prosthesis according to the preceding claim, wherein the cutting angles of the section of the amounts of crowns and / or vertices and / or connectors are different. 8. Prosthesis according to any one of the preceding claims, wherein the non-resorbable mesh is based on chromium-cobalt or nitinol. Prosthesis according to any one of the preceding claims, wherein the bioabsorbable means (12) comprise a bio-absorbable ceramic. 10. Prosthesis according to any one of the preceding claims, wherein the non-absorbable (11) and bioabsorbable meshes (12) mutually cooperate substantially at the non-rectilinear flexible portions (112Ay, 112By, 123Ay). amounts respectively connecting two vertices of the same crown.

Prosthesis according to the preceding claim, wherein the flexible portion (123Ay) of an amount (123) of the bioabsorbable structure (12) has a recess (123Ayr) to partially accommodate the flexible portion (112Ay) of a post ( 112A) of the non-resorbable mesh (11).

A prosthesis according to any one of the preceding claims, wherein the bioabsorbable means are impregnated with one or more drug agents of a group consisting of anti-inflammatory, antiproliferative, antiplatelet, anticoagulant, anti-thrombotic or anti-inflammatory agents. adhesion, growth and maturation of endothelial cells.

Prosthesis according to any one of the preceding claims, comprising a permanent coating or bioabsorbable polymer which covers all or part of the assembly consisting of non-resorbable mesh (11) and bioabsorbable (12).

14. Prosthesis according to the preceding claim, wherein the coating is arranged to degrade completely in a few weeks to a few months by emitting substances having a particular effect or a plurality of effects, including anti-inflammatory, antiplatelet effects, anticoagulant, anti-thrombotic and antiproliferative. The prosthesis of claim 13 wherein the coating comprises a lipid or lipid layers for targeting and attracting endothelial cells or promoting the development of such cells around lattices (11, 12).

Prosthesis according to any one of the preceding claims, comprising radio-opaque means (13, 14) located at the ends of the non-resorbable mesh (11).

Prosthesis according to any one of the preceding claims, comprising a quantity of bioabsorbable means (12) substantially equivalent to that of the non-resorbable mesh (11).