WO2010097236A1

WO2010097236A1 - Medical implant, method for the production thereof, medical device, and method for introducing a medical implant into a supply system

Info

Publication number: WO2010097236A1
Application number: PCT/EP2010/001215
Authority: WO
Inventors: Giorgio Cattanaeo
Original assignee: Acandis Gmbh & Co.Kg
Priority date: 2009-02-26
Filing date: 2010-02-26
Publication date: 2010-09-02
Also published as: DE102009010824A1; DE102009010824B4; WO2010097236A8; EP2400932A1

Abstract

The invention relates to a medical implant comprising a wall (10) that is curved at least in some sections in the implanted state and that comprises a grid structure (11) having grid cells (14), wherein the grid cells (14) can be deformed in the longitudinal direction of the implant in such a way that the grid structure (11) is flexible for adjusting to a vessel. The invention is characterized in that the grid structure (11) comprises folding means (12) that are adjusted in such a way that the grid structure (11) can be brought from an expanded state I to a compressed folded state II for introduction into a feed system, radially inwardly protruding folded sections (13) being formed in the process.

Description

Medical implant, method for its manufacture, medical device and method for introducing a medical implant into a delivery system

description

The invention relates to a medical implant and a method for the production thereof, to a medical device and to a method for introducing a medical implant into a delivery system.

A generic implant having the features of the preamble of claim 1 is known for example from US 6,843,802 Bl. The implant according to US Pat. No. 6,843,802 B1 is a self-expanding stent whose wall is formed from a lattice structure. The grid structure comprises closed grid cells whose geometry determines the flexibility of the stent. Good flexibility is important to be able to implant the stent in tortuous vessels with small radii of curvature.

In the stent according to US Pat. No. 6,843,802 B1, the geometry which causes the flexibility in the implanted state is achieved by the elongated shape of the lattice cells, which lead to an extension of the stent when deformed. The geometry of the grid cells of the stent according to US Pat. No. 6,843,802 B1 has the disadvantage that they are compressed during compression, i. crimping and insertion into a delivery system such as a catheter results in distortion of the lattice structure. This makes it difficult to accommodate the stent in the delivery system.

The invention has for its object to improve a medical implant of the type mentioned so that the implant on the one hand in the implanted state has good flexibility and on the other hand can be easily inserted into a delivery system. The invention is further based on the object of specifying a method for producing such an implant and a method for introducing a medical implant into a delivery system (working method). According to the invention, this object is achieved with respect to the medical implant by the subject-matter of claim 1, with regard to the manufacturing method by the subject-matter of claim 19, with regard to the working method by the subject-matter of claim 21 and with respect to the medical device by the article of claim 22 solved.

The invention is based on the idea of specifying a medical implant with a wall which is curved at least in sections in the implanted state and which comprises a lattice structure with lattice cells, wherein the lattice cells can be deformed in the longitudinal direction of the implant in such a way that the lattice structure is flexible for adaptation to a vessel , The lattice structure has folding means which are adapted such that the lattice structure for introduction into a feed system can be converted from an expanded state into a compressed folding state to form radially inwardly protruding fold sections.

The invention has the advantage that in the vessel, i. flexibility required in the implanted state and for crimping. or introducing into the supply system required flexibility by different means and / or different mechanisms is achieved. The flexibility required for crimping and the flexibility required in the vessel are thus decoupled.

For this purpose, the grid structure has folding means which are adapted such that the grid structure can be converted from an expanded state into a compressed folding state to form radially inwardly projecting folding sections. The flexibility required for crimping is achieved mainly by the folding means and the associated folding process. The flexibility required in the vessel is provided by the lattice structure per se, in particular by its cell geometry, which is adapted such that a deformation of the cell geometry, or generally by a deformation of the lattice structure forming grid elements allows adaptation of the implant to the vessel becomes.

In contrast to the deformation by the Faltπiittεl acting radially inward, the deformation of the grid elements for adaptation of the implant takes place in the vessel in the longitudinal direction of the implant, or generally parallel to the wall. In this way, the flexibility required in each case for the different functions, namely, on the one hand, the flexibility required for crimping and, on the other hand, the flexibility required in the vessel, can be independently optimized or adjusted. This results in the overall advantage that the implant according to the invention for the adjustment of the flexibility is not bound to a parameter, such as the opening angle of the grid cell, in particular the diamond angle of a diamond-shaped grid cell. Although a large diamond angle is advantageous overall for the flexibility, it is disadvantageous for the crimping since the diamond-shaped grid cell or, in general, the grid cell is subjected to excessive distortion when the webs are pressed against one another almost parallel during crimping. If the opening angle of the grid cell is the only parameter which determines the flexibility, the deformability of the grid cell determines the crimping capacity of the implant. In view of the influence of the deformability of the grid cell on the crimping capacity of the implant, a small opening angle of the grid cell or a small diamond angle is advantageous, which allows an approximately parallel arrangement of the grid bars in the crimped state. On the other hand, a significant elongation of the grid cell, in particular the diamond-shaped grid cell, is made difficult by a small opening angle or a small diamond angle, so that the flexibility of the grid cell in the implanted state is limited. For example, a diamond-shaped grid cell with a diamond angle of 40 ° can be extended by a maximum of 6%. A stent with such a diamond angle can easily collapse in the curved state, since the two opposing stent sides are unstable due to the different radii of curvature and, associated therewith, the different elongation of the sides. The decoupling of the flexibility required for the crimping and the flexibility required for the adaptation to the vessel by the foldability of the lattice structure releases the counteracting effects of a large or small opening angle of a lattice zeil.

Although it is known from US Pat. No. 6,843,802 B1 to use a folding mechanism for crimping the stent. However, this is not a lattice mechanism concerning the grid structure. Rather, in the known graft stent only the cover and not the grid structure is folded. Since the cover is selectively connected to the grid structure at a few points (FIG. 15 of US Pat. No. 6,843,802 B1), there is no significant interaction between the grid structure and the foldable cover of the graft stent influencing the crimping process. The crimping of the lattice structure of the stent according to US 6,843,802 Bl is carried out according to the usual principle, after which the cell lengthens, whereby the entire circumference of the stent is reduced.

In a preferred embodiment, the folding means provides a first degree of flexibility for inserting the grid structure into and through the delivery system Grid structure, a second degree of flexibility for adjusting the lattice structure in the expanded state to a vessel adjustable or adjusted. By adjusting the different degrees of flexibility, the radial force acting on the vessel wall in the implanted state can be achieved independently of the flexibility required for crimping. Thereby, the implant can be constructed without a significant restriction of the respective function between the various mechanisms. The different degrees of flexibility mean that the implant is deformable in the respective state by different sized forces.

In a further embodiment, the lattice structure is adapted such that when moving from the compressed state to the expanded state, the lattice structure unfolds and in the expanded state, the flexibility of the lattice structure is effected by the deformability of the lattice cells in the longitudinal direction of the implant.

Conversely, the deformation force that can be applied to deform the grid structure in the partially expanded state, in particular in a region near the resting state, is smaller than the deformation force required to deform the implant by folding. Thus, in this area, the flexibility by deformation of the lattice structure per se, i. caused by deformation of the lattice structure within the wall surface and not by folding the grid structure. With increasing degree of deformation also increases the force required for the deformation of the grid structure (deformation force) until the required force for the deformation of the grid structure corresponds to the force required for the deformation of the implant by the folding force. After falling below the associated critical diameter, which can be determined by the expert experimentally for each implant, the force required to fold the implant elastic force and thus the restoring force is less than the force required for elastic deformation of the grid structure with the Result that the folding process of the implant is initiated.

The geometry of the grid structure is adapted in this embodiment so that the deformation of the grid elements mainly causes the adaptation of the implant to the vessel diameter.

The grid structure preferably has closed grid cells, in particular diamond-shaped grid cells. Such a configuration is particularly well-suited in connection with the folding means to the required in the implanted state in the vessel flexibility by deformation of the diamonds or the grid cells enable. In this case, lozenges with a large angle are particularly preferred because this allows easy deformation and adaptation to the vessel.

It is also possible to form the grid structure with open grid cells. A grid structure with open and closed grid cells is also possible.

The folding means can be adapted in such a way that the folding sections are arranged wave-shaped in the folded state and in each case one leg of the folding sections is oriented radially inwards. Such an adaptation of the folding means is easy to produce and leads to a good crimpability of the implant to small diameters.

In a further embodiment, it may be provided that the grid structure in the expanded state is wave-shaped, wherein the wave height is smaller in the expanded state than in the folded state. Thus, the implant may have residual fold remaining in the fully expanded state so that the implant does not transition to a smooth cylindrical surface state but will remain in a slightly convoluted configuration even if the grid cells deform. The slightly wavy configuration in the expanded state leads in the implanted state to cavities between the wall of the implant and the inner wall of the vessel, in which, for example, medicaments can be stored. Moreover, an active ingredient in the cavities, e.g. a thrombus dissolving agent, less easily flushed out and thus acts for a long time on a thrombus expanded by the implant, in particular by the stent.

The folding means may comprise folding grooves which are arranged in the longitudinal direction of the implant. The folding grooves have the function of achieving a geometrically determined folding of the implant, which leads to geometrically defined folding sections, in contrast to arbitrary folds. The folding grooves or generally the folding means act similar to predetermined breaking points, but without leading to destruction of the material, but to form at predetermined locations of the lattice structure fold lines or folds in a deformation of the implant, in particular in a radially inwardly acting deformation lead to the formation of the folding sections. The folding grooves can be arranged parallel to the longitudinal axis of the implant and / or spirally. As a result, a folding of the grid structure is achieved along the longitudinal extent of the implant, in particular of the stent. In the spiral arrangement of Faltrillen there is a folding structure in which the wall of the implant verwringt.

The folding grooves may be formed on the inside and / or outside of the grid structure. The arranged on the inside and the outside folding grooves can be arranged offset from one another.

In this way it is possible to realize different folding patterns, which are particularly suitable for the particular application.

The folding grooves can be formed in the grid bars or generally in the grid elements, in particular in the region of connectors. Thus, the folding grooves are formed in the material of the lattice structure. The arrangement of the folding grooves in the region of connectors is particularly advantageous because in a simple manner a symmetrical arrangement of the folding grooves and a good foldability of the grid structure can be achieved. A connector forms a contact point, in particular a connection between two axially downstream grid cells, in particular diamond-shaped grid cells. The connector is not limited to the typically elongated elements used in the design of stents to connect adjacent grid cells, but also includes other configurations.

The wall thickness of the wall may in particular be ≦ 70 μm, ≦ 60 μm, ≦ 50 μm, ≦ 40 μm, ≦ 30 μm, ≦ 20 μm, ≦ 15 μm, ≦ 10 μm. The diameter of the implant in the expanded state can be ≥ 2mm, especially ≥ 3mm, ≥ 4mm, ≥ 5mm, ≥ 6mm, ≥ 7mm, ≥ 8mm, ≥ 9mm, ≥ 10mm. The concept underlying the invention is particularly suitable for stents with thin wall thickness, without being limited thereto. The reduced wall thickness can be combined with large stent diameters in the expanded state. Due to the small wall thickness, crimping into a small catheter diameter is possible despite a large circumference of the stent.

In a particularly preferred embodiment, the folding means comprise connectors which connect at least two Gittεrzεllεn, wherein the connectors each have an S-shaped geometry. The folding means form, as is generally the case with the invention, a part of the lattice structure, be it that they are incorporated in the material of the lattice webs (folding grooves) or in the form of geometrically adapted connectors. The S-shaped geometry of the connectors allows on the one hand a folding and the formation of folding sections when compressing the implant. On the other hand supported the S-shaped geometry provides the flexibility of the implant in the implanted state, as the extension of the implant is achieved not only by the lattice structure but also by the deformation of the S-shaped geometry. The connector with S-shaped geometry can also be considered as an open grid cell in contrast to the diamond-shaped closed grid cell.

The decoupling of the required flexibility for the vessel adjustment in the expanded state and the flexibility required for crimping is also given in this embodiment by the geometric shape of the connector, which has a dual function. On the one hand, the S-shaped geometry of the connector allows for axial elongation upon deformation of the implant in the vessel such that the implant is adaptable to the vessel wall or generally to the vessel. On the other hand, the S-shaped geometry of the connector allows for folding so that the connector provides the flexibility required for crimping. This dual function leads to the advantage that the decoupling of the vessel flexibility and the Crimpflexibilität is partially adjustable in the implant, so that a part of the implant can be produced in a conventional manner and another part of the implant in accordance with the invention with decoupled flexibilities can be realized.

In this case, the connectors may each have a middle section and two outer sections connected to the middle section for forming the S-shaped geometry, the angle between an outer section, in particular between an outer section and the central section ≦ 90 °, in particular ≦ 80 °, ≤ 70 °, <60 °, <50 °, <40 °, <30 °, <20 °, <10 °. As the angle between the outer portion or between the outer portions and the middle portion decreases, the longitudinal extendability of the implant is increased, so that the flexibility given in the implanted state is improved. The middle section and at least one outer section, in particular both outer sections, can be arranged parallel to one another. This achieves a particularly high degree of flexibility in the implanted state.

In another preferred embodiment, two circumferentially juxtaposed connectors are offset longitudinally. This allows a close and compact arrangement of the connectors distributed over the circumference of the implant, in particular of the stent. In another preferred embodiment, the folding means may comprise connectors each connecting two grid cells, the connectors each having a circumferentially oriented U-shaped geometry. This embodiment allows overlapping of the connectors in the folded state, so that the implant can be compressed to particularly small diameter.

With regard to the method, the invention is based on the idea to provide the grid structure with folding means such that the grid structure can be converted from an expanded state to a compressed folding state to form radially inwardly projecting folding sections. In this case, the folding means, in particular folding grooves can be produced by etching, by sinking or wire erosion or by PVD or CVD deposition of a raw material on a mandrel with a negative profile corresponding to the groove profile. The grid structure itself can be made by etching and the base material sputtered. This allows the production of thin wall thicknesses, which are well suited for the implant according to the invention.

According to a sidelined aspect, the invention relates to a medical device, in particular for removing concretions from hollow organs of the body or for recanalizing hollow organs body, with a at least partially curved in the implanted state wall comprising grid structure with grid cells. The grid cells are deformable in the longitudinal direction of the implant in such a way that the grid structure is flexible for adaptation to a vessel. The lattice structure has folding means which are adapted such that the lattice structure for introduction into a feed system with the formation of radially inwardly projecting fold sections from an expanded state I to a compressed folding state II is traversable.

The features of the dependent claims related to claim 1 or generally the dependent claims 1 to 18 form analogously preferred embodiments of the medical device according to claim 22 and are also disclosed and claimed in connection with the medical device.

The manufacturing method disclosed in connection with the implant described above is also suitable for the manufacture of the medical device and is also disclosed and claimed as a manufacturing method for the medical device. In particular, the medical device according to the invention comprises devices for removing concretions from hollow organs of the body, for example thrombus removal systems, baskets or suction baskets for gripping or retaining concretions, in particular thrombi, and recanalization systems, filters, for example for the treatment of carotid -Stenose, or occlusion systems. The flexibility provided by the folding sections is particularly advantageous in the medical devices according to the invention, since such medical devices are often moved during a treatment within hollow body organs, in particular blood vessels. It is achieved by the high degree of flexibility that the medical device can be performed relatively easily and safely by curved body hollow organs. Preferably, the medical device has a relatively large ridge width. This ensures that the degree of coverage of the grid structure is increased. The ratio between land width and cell diameter of the grid structure is in favor of the web width. This achieves advantageous protection against particle detachment. This means that particles separated from a concrement are effectively retained.

In general, it is possible to provide both the medical implant described above and the medical device with a cover. In particular, the grid structure of the implant or of the device can have a coating or covering, preferably comprising a plastic, for example polyurethane.

When compressing the lattice structure, the cells of the lattice structure can deform to a certain degree. Beyond this degree of deformation, the folding of the lattice structure takes place, forming the radially inwardly projecting folding sections. During folding, there is essentially no deformation of the cells. In particular, an extension, ie an increase in the longitudinal extent of the cell, does not occur in the folding process substantially. This prevents overstretching of the coating or covering of the cells.

During folding, there is also a comparatively limited shortening of the cell width in the circumferential direction of the tubular lattice structure. This prevents the fabric or coating from curling or curling during compression or crimping. The forces required for the delivery of the implant or the device for moving the implant or the device in a supply system, preferably a catheter, are thus reduced. The aforementioned properties of cell deformation or folding apply both to the implant described above and to the medical device.

The invention will be explained in more detail below with reference to embodiments with further details with reference to the accompanying schematic drawings. In this show:

1 shows a cross section through a stent according to an inventive

Embodiment in a catheter (folded state II);

FIG. 2 shows the stent according to FIG. 1 in the partially expanded state I in the vessel; FIG.

3 is a plan view of the grid structure of a stent according to an embodiment of the invention with folding grooves.

4 shows a cross section through the stent according to FIG. 3;

Fig. 5 shows a cross section through a stent with on the inside and the

Outside staggered folding grooves;

6 shows a section of a grid structure of a stent according to an embodiment of the invention, in which two grid cells are connected by a connector with S-shaped geometry;

Fig. 7 shows a detail of a stent according to an inventive

Embodiment with staggered connectors;

Fig. 8 shows a cross section through the stent of FIG. 7 in the compressed

Condition within a delivery system;

9 shows a detail of a stent according to another invention

Ausführαngsbeispiel with U-shaped connectors;

Fig. 10 shows a cross section through the stent of FIG. 9 in the compressed

Condition within a delivery system; 11 is a schematic representation of a stent according to an embodiment of the invention in the implanted state.

Fig. 12a, 12b shows an arrangement of four diamond-shaped grid cells for explaining the structure can be generated by the lattice flexibility;

13a, 13b show two different states of deformation of the arrangement according to FIG. 12a, FIG.

12b; Figs. 14a, 14b show an arrangement of four diamond-shaped grid cells with another

Diamond angles and

Fig. 15 shows the arrangement of FIG. 12a to illustrate the cell dimensions.

FIGS. 1 and 2 each show a cross section through a medical implant in the folded state II and in the expanded state I. The implant is a stent, ie a tube-shaped stent, which is preferably used in the neuronal area. Other implants that are inserted into a delivery system for implantation and released in the body are possible. The invention generally includes, but is not limited to, rotationally symmetric implants, such as stents or thrombosis receivers. The invention is applicable to all implants which, for insertion into the body, are introduced into a delivery system, for example into a microcatheter, and discharged in the body. The invention is also applicable to all medical devices that are only temporarily discharged in the circulation or in body cavities and then withdrawn, such as catch baskets. Such devices are also understood as implants in the context of the invention.

The stent according to FIG. 1, 2 has an at least partially curved wall, in particular a cylindrical wall. The wall comprises a lattice structure which is designed to be flexible such that the lattice structure in the implanted state can be adapted to a vessel.

For introducing the implant into a delivery system, for example into a catheter, the lattice structure has folding means which are adapted such that the lattice structure 11 can be converted from an expanded state I into a compressed folded state II to form radially inwardly projecting fold sections 13 is. The required for the crimping diameter change is thus not primarily by in the Lattice structure formed lattice cells 14, but mainly achieved by the folding means 12, so that the flexibility required for the crimpability is decoupled from the flexibility required in the implanted state in the vessel, in particular for adaptation to strong curvatures. For this purpose, the grid structure of the stent or generally of the implant is foldable such that the outer diameter of the stent for crimping can be reduced. Although deformation of the grid cells 14 during crimping is not excluded, it is not decisive for the crimp flexibility that is achieved primarily by folding.

The grid cells are adapted such that when transferred from the expanded state I in the compressed state II, the grid cells 14 are deformable, in particular in the longitudinal direction of the implant until the force required for the deformation of the grid cells 14 is greater than that for folding the Grid structure required force. The grid cells and the folding means are thus matched to one another in such a way that the deformation of the individual grid cells 14 passes into the folding process at a limit force which can be determined by a person skilled in the art as required.

The folding means 12 are generally elements or components of the grid structure 11, which have the function to initiate the folding at predetermined locations of the wall 10 upon application of the stent with a radially inwardly acting compressive force and the grid structure 11 to form radially inwardly projecting folding sections 13 in the compressed folding state II to convict. The folding sections 13 can also be arranged in regions on the circumference and abut against this. The folding means 12 can in this case be incorporated into the material of the wall 10 or the lattice structure 11, for example in the form of folding grooves 16. It is also possible, for example in a stent made from a shape memory material, to specify a desired folding structure by suitable conditioning of the material , In this context, the folding means 12 correspond to the structural properties created by the conditioning. It is also possible that the expanded end state, as shown in Fig. 2, is adjusted so that it has a residual fold or a wave-shaped profile.

In addition to forming the folding means 12 as elements of the grid structure 11 or in the form of a structural feature, the folding means 12 may comprise a configuration of the grid structure 11 having, for example, a retired wavy profile in cross-section, as described below, such that the undulating profile an orderly folding of the stent for crimping takes place. Moreover, it is possible to realize the folding means 12 by a geometry of the grid elements. For example, the web width in certain areas, for example in the region of the connectors, be thinner than at other locations of the grid structure 11 such that folds form in the region of the thin web widths at which preferably the folding of the grid structure 11 occurs.

In general, it is possible with closed grid cells 14, for example in diamond-shaped closed grid cells 14, to adjust the geometry of the grid cells 14 so that a maximum longitudinal deformation of the grid cells in the longitudinal direction of the implant can be achieved during the transition from the expanded state I to the compressed state II Exceeding the, by the expert experimentally determinable, maximum deformation uses the folding of the lattice structure. The lattice structure is thus adapted such that the deformability of the lattice cells in the longitudinal direction of the implant and the folding capacity of the lattice structure are matched, so that with increasing compression of the implant instead of the deformation of the lattice cells in the longitudinal direction, the radially inwardly directed folding of the lattice structure occurs.

In the stent according to FIG. 1, the radially inwardly projecting folding sections 13 form a substantially star-shaped or wave-shaped profile. By folding a relatively large surface of the wall 10 is arranged on a relatively small circumference with a small outer diameter. The corrugated folding sections 13 each include legs 15 which are oriented radially inwardly. The legs 15 connect shaft tips 15a and troughs 15b, with the troughs 15b defining the lumen and the shaft tips 15a defining the outer circumference of the compressed stent. The shaft tips 15a are, as shown in Fig. 1, in contact with the inner wall of the catheter K. Two circumferentially juxtaposed legs 15 form in cross-section V. The wave-shaped profile results from the arranged on the circumference lining up the V-shaped arranged leg 15.

The folding sections 13 can not only be oriented radially inwards, but also partially folded on the circumference, which reduces the space requirement of the stent in the crimping state. This is generally true for all embodiments of the invention. Specifically, in the embodiment according to FIG. 1, the legs 15 can be extended such that a part of the folding sections 13 projects radially inwards into the lumen and another part of the folding sections 13 is arranged or folded on the circumference of the folded implant. The folding shown in FIG. 1 avoids distortion of the grid cells 14 in the longitudinal direction during folding in the feed system.

2, a partially expanded state I is shown, wherein the restoring force of the stent has approximately restored the originally cylindrical configuration and led to the dilation of the vessel G. It is also possible that the expanded state I shown in FIG. 2 represents the final state which differs from the crimped state by another wave height W. In this case, the wave height W forms the distance between a wave tip 15a and a wave valley 15b.

The recognizable in Fig. 2 cavities 23 between the stent wall 10 and the vessel G can be used for storage of drugs, such as thrombolytic agents. The agents remain in the cavities 23 for a relatively long time, whereby their effect, for example on a third thrombus softened by the stent, is improved. In addition, the wave-shaped configuration with smaller wave height formed in the expanded state I can be used as a folding means 12 to allow a controlled and predetermined folding of the stent from the expanded state I according to FIG. 2 into the folded state II according to FIG. In this respect, the shaft tips 15a provided in the wave-shaped configuration according to FIG. 2 together with the wave troughs 15b form folding means 12 which initiate the controlled folding of the lattice structure 11 when the wall is acted upon by a radially inwardly directed pressure force.

In addition or as an alternative to the wave-shaped configuration according to FIG. 2, the folding means 12 may be designed in the form of folding grooves 16, as shown in FIG. The folding grooves are formed in the material of the grid bars 18 and extend in the longitudinal direction L of the stent, as illustrated in FIG. 3. The folding grooves 16 are arranged so that a plurality of folding grooves 16 are arranged in alignment in the longitudinal direction L. The folding grooves 16 are thus located on an imaginary line which runs parallel to the stent central axis and forms a fold line. Several of these fold lines are distributed in the circumferential direction, as shown in Fig. 3. The fold lines are arranged in parallel. It is also possible to arrange the folding grooves spirally on the circumference of the stent such that spiral fold lines are formed. A plurality of spiral fold lines are provided adjacent to one another such that the fold lines are arranged in parallel. In both examples, the folding grooves 16 function to initiate a controlled folding to form fold sections 13 when the grid structure 11 is subjected to a radially inwardly acting compressive force.

In the embodiment of FIG. 3, the folding grooves are arranged in the region of the connectors 19, which are provided between two circumferentially adjacent grid cells 14 and connect them. The folding grooves are arranged on the axis of a diamond-shaped grid cell 14. It is also possible to arrange the folding grooves elsewhere, so that the folding grooves 16 intersect the grid bars 18. Again, it is possible to arrange the folding grooves 16 in alignment in the longitudinal direction L of the stent, wherein a parallel or spiral arrangement can be realized.

FIGS. 4, 5 show two examples of how the folding grooves 16 are distributed over the circumference. In the embodiment according to FIG. 4, the folding grooves 16 are arranged on the outer side 17b of the stent. The inside 17a is free of folding grooves. In the embodiment according to FIG. 5, the folding grooves 16 are provided on the inner side 17a and on the outer side 17b. In this case, the folding grooves 16 on the inner side 17a and on the outer side 17b offset from each other are arranged such that between two outer folding grooves 16 centrally an internally arranged Faltrille 16 is provided. The folding grooves 16 are arranged on the inner side 17a and on the outer side 17b with the same distance from each other. Another arrangement of the folding grooves 16 is possible.

The exemplary embodiments shown in FIGS. 1 to 5, like the other exemplary embodiments, are particularly suitable for thin-walled stents, without being limited thereto. For example, the folding means 12 can be provided via a stent with a wall thickness ≦ 70 μm, in particular ≦ 60 μm, ≦ 50 μm, ≦ 30 μm, ≦ 20 μm, ≦ 15 μm, ≦ 10 μm in such a way that the stent is inserted into a catheter an inner diameter of 0.6 mm can be crimped by the folding technique described above.

Smaller wall thicknesses allow the stent to be folded into catheters with smaller inside diameters. The smaller the wall thickness, the larger the diameter of the stent can be in the expanded state. It is possible that a stent which can be crimped into a catheter having an inner diameter of 0.6 mm has an outer diameter in the expanded state of at least 2 mm, in particular at least 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm. The invention is based on the above Values not limited nor to the following example: A stent with a wall thickness of 20 μm and a diameter of 4.0 mm in the expanded state has approximately 65% of the total cross-section in a state crimped in the catheter with an internal diameter of 0.7 mm , The remaining free space would allow space between the legs which limit the folding radius and provide space, for example, for insertion of a guidewire.

The width of the grid webs 18 may be ≦ 40 μm, in particular ≦ 30 μm, in particular ≦ 25 μm, in particular ≦ 20 μm, in particular ≦ 15 μm. The width of the lattice webs 18 may in particular be at least 30 .mu.m, in particular at least 40 .mu.m, in particular at least 50 .mu.m, in particular at least 100 .mu.m, in particular at least 150 .mu.m, in particular at least 200 .mu.m, in particular at least 250 .mu.m, in particular at least 300 .mu.m, in particular at least 400 .mu.m , amount. The abovementioned values for the minimum width for the grid webs 18 are particularly advantageous given a rest diameter of the implant or of the medical device up to a maximum of 4 mm. With a rest diameter of the implant or the medical device of at least 8 mm, it is preferred if the grid bars 18 have a width which is at least 350 μm, in particular at least 400 μm, in particular at least 450 μm, in particular at least 500 μm, in particular at least 600 μm , is. The width of the grid webs generally refers to a region of the grid web 18, for example a free web section between two connection points or an area in the vicinity of a connection point between the grid cells 14.

The diamond angle of the grid cell 14 may be> 60 °, in particular ≥75 °, in particular ≥ 90 °, in particular ≥ 105 °, in particular ≥ 120 °, in particular ≥ 135 °. The ratio between the diameter of the stent in the expanded state and the inner diameter of the catheter may be ≥ 3, in particular ≥ 4, ≥ 6, ≥ 8, ≥ 10. The inner diameter of the catheter may be ≦ 1.4 mm, in particular ≦ 1, 2, ≦ 1, 0, ≦ 0.9, ≦ 0.8, <0.7, <0.6, <0.5 mm.

As shown in FIG. 15, the diameter of a grid cell may be determined by a circle written in the grid cell. The diameter of the grid cell can be between 100 μm and 1000 μm, in particular between 100 μm to 800 μm, 100 to 600 μm, 100 to 400 μm, 100 to 300 μm. The ratio between the land width b as shown in FIG. 15 and the cell diameter may be ≦ 0.2, <0.1, < 0.08, <0.06, <0.05, <0.04, <0.03. For example, in the case of a ratio of 0.05, the land width is 15 μm and the diameter is 300 μm.

The ratio between web width b and web thickness can be at least 0.5, in particular at least 1, in particular at least 2, in particular at least 3, in particular at least 5, in particular at least 7, in particular at least 10, in particular at least 15, in particular at least 20. The grid cells 14 also have a cell circle diameter defined as the diameter of the largest possible circle writable into a grid cell 14. In other words, the cell circle diameter corresponds to the diameter of the largest possible cylinder, which can be inserted through a grid cell 14 in the expanded state or idle state of the lattice structure 11. The ratio of the web width b to the cell circle diameter is preferably at least 0.2, in particular at least 0.5, in particular at least 1, in particular at least 1.5, in particular at least 2, in particular at least 2.5, in particular at least 3.

In general, the folding of the lattice structure 11 is facilitated by a high web width b or a large ratio between web width b and web thickness or wall thickness of the grid structure 11. Moreover, the degree of coverage of the grid structure 11 and the wall 10 is increased. This applies to all embodiments mentioned in the application, in particular both for the implant, and the medical device.

For the entire application, the stent or the implant is coated or coated or made of a bioresorbable material.

It is also possible, as explained with reference to the example according to FIG. 6, that the connectors 19 are formed between the grid cells 14 as connecting elements which, in addition to the folding function, cause an extension of the stent in the implanted state and thus the vessel flexibility. The connector 19 thus functions both as a folding means 12 and as an extension means for the stent in the implanted state. For this purpose, the connector 19, as shown in Fig. 6, with an S-shaped geometry b ^ w. equipped with an S-shaped profile which is extensible in the longitudinal direction L. The area shown in Fig. 6, which is bounded by the connector 19, thus forming the

Main extension range for the vessel flexibility, which is thus achieved primarily by the connector 19 and not by the grid cells 14. The S-shaped profile of the connector 19 comprises a central portion 20a and two at the ends of the outer sections 20b, 20c arranged in the middle section 20a. The sections 20a, 20b, 20c are arranged in an S-shape, wherein the outer sections 20b, 20c and the middle section 20a are arranged parallel in the undeformed state or at a small angle to one another. To extend the stent in the longitudinal direction, the outer sections 20b, 20c can be bent in the longitudinal direction L, so that the outer sections 20b, 20c are arranged at an angle to the central section 20a. As a result, the distance between the diamonds 14 shown in FIG. 6 is increased. The outer portions 20b, 20c are connected to the middle portion 20a by curved connecting portions 20d forming a curvature of 180 ° or less. The outer sections 20b, 20c are connected to the grid cells 14 by further connecting sections 2Oe, which have a radius of curvature of 90 °.

In Fig. 7, the arrangement of a plurality of circumferentially distributed S-shaped connector 19 is shown. The S-shaped geometry of the juxtaposed connectors 19 is also circumferentially oriented such that the central portions 20a of the various connectors 19 are each circumferentially oriented.

For a compact arrangement of the connector 19, these are arranged offset in the longitudinal direction L. For this purpose, the connection elements 2Oe connected to the grid cells 14 are alternately extended such that an extended connection section 20e is connected to a grid cell 14 upstream in the longitudinal direction L and a further connection section 2Oe of the next connector in the circumferential direction U is connected to a grid cell 14 arranged downstream in the longitudinal direction L. It is thereby achieved that the middle portions 20a of circumferentially adjacent U connectors 19 are arranged at different altitudes, so that a part of the central portions 20a and the associated outer portions 20b, 20c in the circumferential direction U are arranged overlapping side by side. Overall, an alternating pattern of offset connectors 19 results which are distributed over the circumference of the stent.

The resulting from the configuration of FIG. 7 folding structure is shown in Fig. 8. There it can be seen that crimping forms inwardly oriented folding sections 13 which project into the lumen of the stent. This means that the connectors 19 according to Figure 7 are not only responsible for the extension of the stent and thus for the vessel flexibility, but also simplify the crimping by the foldability. The decoupling of the crimp flexibility and the vessel flexibility is achieved by the S-shaped geometry of the connector 19. For flexibility in the vessel radius extends the connector 19. For crimping the connector 19 folds inwards. The imple mentation form of FIG. 7 may be combined with the folding grooves described above.

Overall, the configuration and arrangement of the connector 19 results in two things:

On the one hand, the S-shaped connectors 19 form an example that the structure responsible for the folding structure or the folding means 12 may be realized in an open grid cell. In this case, the S-shaped connector 19 or the S-shaped open grid cell behaves like a diamond-shaped grid cell 14 with a very large angle, so that the connector 19 can be greatly extended to a certain limit, thereby increasing the flexibility of the stent in the vessel becomes. After the allowed deformation, a distortion occurs in the area of the connector 19, which prevents a full extension of the S-shaped connector 19 in the longitudinal direction of the stent, so that only by the deformation of the S-shaped connector 19 in the longitudinal direction of the required for crimping Flexibility is not possible. Analogous to the diamond-shaped grid cells 14 or generally to the closed grid cells, it is therefore provided in the connector 19 according to FIGS. 6 to 8 that these fold during crimping. This is achieved in that the middle section 20a deforms in a U-shaped manner when falling below the critical diameter, which can be determined experimentally, so that a folding section 13, as shown in FIG. 8, is formed. In this case, the latticed diamonds 14, as shown in Fig. 8, arranged on the circumference of the crimped stent and abut against the catheter inner wall. The inwardly projecting folding portions 13 correspond to the folded connectors 19, in particular the U-shaped or V-shaped middle portions 20a and the entrained outer portions 20b, 20c.

When crimping, the S-shaped connectors are approximated to each other at the periphery until they can no longer escape. Due to the symmetrical arrangement of the S-shaped connectors, the longest connector portion, namely the middle portion 20a of the respective connector folds inwardly in a V- or U-shape, thus forming the folding means 12.

On the other hand, the connectors 19 lead to a further advantage. Namely, the folding process may be limited to one or more areas of the stent due to the connectors 19. A folding of the stent along its entire length is then not required. The closed grid cells 14 serve in this case to close the structure on the circumference in segments. The grid cells 14 can therefore a small Have opening angle or diamond angle, which is adapted such that it allows the crimpability of the stent. Since the vessel flexibility is achieved by the longitudinal deformability of the S-shaped connector 19, does not affect the vessel flexibility by the small opening angle. It is also possible to make the grid cells 14 foldable by further folding means 12, for example by folding grooves 16 for crimping.

The operation described in connection with the S-shaped connectors 19, in particular their dual function, also applies to the U-shaped connector 19 described below.

Another embodiment, in which the connectors 19 allow both the folding and the extension of the stent in the longitudinal direction L, is shown in FIGS. 9, 10. It can be seen that each of the two grid cells 14 connecting connector 19 each have a circumferentially U oriented U-shaped geometry.

As shown in Fig. 10, when crimped, the U-shaped connectors 19 fold into a catheter K radially inwardly and overlap in the circumferential direction. The U-shaped geometry of the connector 19 also ensures that they cause an extension of the stent in the longitudinal direction L by expanding, that is, by opening the U-shaped geometry.

The mode of operation and production of the stent according to the preceding embodiments will be explained below.

As shown in FIG. 11, when the stent 21 is implanted in a vessel G, the inner radius 22b is more curved than the outer radius 22a. The stent is therefore sufficiently flexible to allow a high curvature, in particular the different curvatures in the different stent areas 22a, 22b. The flexibility of the vessel, that is to say the flexibility applied by the stent in the implanted state, is made possible by the lattice structure and / or by the formation of the connectors with a structure that can be extended locally in the longitudinal direction. Concretely, when the stent is bent, the outside thereof is longer than the inside thereof. The deformation process responsible for the flexibility of the stent is described below:

With a large stent diameter, in particular in the expanded state (resting state), but also in a region near the rest state, ie in a diameter range from a partially expanded intermediate state to fully expanded state, an inwardly directed with respect to the stent outer force leads to deformation the diamond-shaped grid cells 14, without causing a convolution. In this diameter range, which is determined inter alia by the opening angle of the grid cells 14, in particular grid-shaped diamonds, only a deformation of the grid cell 14 takes place due to the large diamond angle. This is because in this diameter range, the elastic deformation force (restoring force) by folding the lattice structure is greater than the deformation force required for the deformation of the diamond-shaped lattice cells 14, with the result that in this diameter region, the inwardly directed vascular force by a deformation of the diamond-shaped Grid cell 14 is recorded. The same applies to a deformation of the stent by a vessel curvature, which is also compensated by the deformation of the diamond-shaped grid cell 14, which leads to an extension of the cell and thus of the stent in the highly deformed area. This achieves the flexibility of the stent in the implanted state or in the region near the resting state.

After falling below the critical stent diameter required for folding the stent elastic deformation force and thus the restoring force is smaller than the force required for elastic deformation of the diamond-shaped grid cell 14. This is because the diamond-shaped grid cell 14, especially if it has a large diamond angle, can deform only to a certain extent with an appropriate force. Below the critical stent diameter increases the force required for the deformation of the grid cell 14, so that the folding of the stent is initiated.

The critical stent diameter, which forms the boundary between the deformation of the grid cell (vessel flexibility) and the folding of the grid structure (Crirnpflεxibilität) can be determined experimentally by the skilled person. The principle is that in the

Vascular diameter range, ie in the area near the resting state of the stent deformed rather in the cell geometry and only with a further reduction in diameter occurs the folding of the stent. For example, a stent with a diameter of 5mm may be used to treat a vessel with a Diameter between 4 and 5mm can be used. The stent can be designed so that the reduction of the diameter up to a diameter of 3.5 mm by the deformation of the diamond-shaped grid cell or generally by the deformation of the grid cell. In this area, the deformation of the grid cell 14 takes place in the vessel curvature. Below this diameter range, the elastic deformation to form the folding portions 13 is smaller than the elastic deformation of the grid cell 14, in particular the diamond-shaped grid cell 14. The stent begins to fold.

Overall, this means that the stent deforms depending on the minimum strain energy. Since the stent is adapted to fold in an ordered manner, excessive distortion of the lattice cells 14 below a limiting diameter is avoided. On the other hand, the stent is adapted so that the grid cells 14 are deformable in a diameter region near the fully expanded state so that the adaptation in the vessel is effected by the mechanism of the grid cell deformation.

The diameter range in which the flexibility of the stent is determined by the deformation of the grid cells 14 can be between 0% (fully expanded state) and 5% (limiting diameter), in particular between 0% -10%, in particular between 0% -15%, in particular between 0% -20%, in particular between 0% -25%, in particular between 0% -30%.

With the onset of folding, the grid cells 14 may be partially deformed. The grid cells 14 may be adapted such that they remain in the deformed state during folding or the deformation of the grid cells 14 partially or completely diminishes. It is also possible to adapt the grid cells 14 so that they are increasingly deformed during folding in such a way that during progressive folding the grid cells undergo additional deformation.

Good vascular flexibility is achieved independently of the support by a connector which can be expanded in the longitudinal direction of the implant by the largest possible diamond angle α, as shown in FIG. 12a. The groove angle GC can be ≥ 60 °, in particular 90 90 °, ≥ 120 ° or> 150 °. When the stent is loaded in the implanted state, for example, as shown in Fig. 11, deformation of the grid cells 14 takes place, as shown in Fig. 12b. The diamond-shaped grid cells 14 length and the diamond angle ß is reduced. As illustrated in the following figures 13 and 14, a large diamond angle α leads to greater flexibility, since at a large diamond angle α a relatively small deformation in the longitudinal direction (diamond angle ß) sufficient to achieve, for example, an elongation of 40% of the diamond-shaped grid cell or the stent. As is readily apparent from Figures 14a, 14b, much greater distortion of the grid structure is required to achieve the same 40% elongation at a smaller diamond angle α. By decoupling the Crimpflexibilität and the vessel flexibility, it is possible to influence the latter by a suitable choice of the diamond angle, in particular by a maximum possible diamond angle α, without affecting the crimpability of the stent. This is due to the fact that the Crimpflexibilität the stent is achieved by other means than the vessel flexibility, namely by the folding means 12. The folding means 12 are adapted so that they allow a targeted folding of the lattice structure to form geometrically determined folding sections.

For the production of the stent known per se

Surface processing methods, such as the partial etching, are used. Thus, for example, it is possible to introduce the folding grooves 16 on the outer surface of the stent by partial etching. The formation of the folding grooves 16 on the inner side 17a of the stent can be done for example by sinking or wire erosion of the tube. It is also possible to deposit the pipe material on a mandrel, in particular by sputtering, which has a corresponding negative profile. The S- or U-shaped connectors can be made for example by laser cutting.

Furthermore, a method for crimping an implant, in particular a stent is disclosed and claimed, which is characterized in that for introduction into a supply system to form radially inwardly projecting folding portions 13 from an expanded state I into a compressed folding state II can be transferred. All features described in connection with the implant and its operation are disclosed in the context of the method of crimping an implant.

The invention is particularly suitable for implants with closed cells, in particular with a diamond-shaped grid Lr uktur 11, without being limited thereto. In addition, other profiles in which the individual stent webs deform in an optimal way, possible. For example, it is possible that the webs have a corrugated shape in itself, so that the deformation of the grid cells, in particular the diamond-shaped grid cells is distributed over the entire web. All features of the above embodiments are also in connection with the medical device, in particular in connection with temporarily insertable into the body devices, such as devices for removing concrements, especially thrombus removal systems or thrombectomy devices, baskets, in particular suction baskets Gripping or catching of thrombi or concretions in general, and systems and devices for recanalizing hollow organs of the body, in particular recanalization systems, filters, for example for the treatment of carotid stenosis, and / or occlusion systems, are disclosed and claimed.

LIST OF REFERENCE NUMBERS

10 wall

11 lattice structure

12 folding means

13 folding sections

14 grid cells

15 thighs

15a wave tips

15b wave troughs

16 folding grooves

17a inside

17b outside

18 grid bars

19 connectors

20a middle section

20b, c outside sections

2Od, e connecting sections

21 stents

22a, 22b curved sections

I expanded state

II folding condition

G vessel K catheter

W wave height

Claims

claims

1. A medical implant having a wall (10) curved at least in sections in the implanted state and comprising a grid structure (11) with grid cells (14), wherein the grid cells (14) are deformable in the longitudinal direction of the implant such that the grid structure (11) is flexible for adaptation to a vessel, as it is characterized in that the lattice structure (11) has folding means (12) which are adapted such that the lattice structure (11) for insertion into a feed system to form radially inward projecting folding portions (13) from an expanded state I in a compressed folding state II can be transferred.

2. Implant according to claim 1, characterized in that by the folding means (12) a first degree of flexibility for introducing the lattice structure (11) into the delivery system and through the lattice structure (11) a second degree of flexibility for adapting the lattice structure (11) is set or adjusted in the expanded state to a vessel.

3. The implant according to claim 1 or 2, since by means of the fact that the lattice structure (11) is adapted such that the lattice structure develops during the transition from the compressed state II to the expanded state I and the flexibility of the lattice structure in the expanded state I is caused by the deformability of the grid cells in the longitudinal direction of the implant.

4. The implant according to claim 1, wherein the grid structure has closed grid cells, in particular diamond-shaped gingerkin cells and / or open gastric cells.

5. Implant according to at least one of claims 1 to 4, characterized in that the folding means (12) are adapted such that the folding sections (13) in the Folded state II wave-shaped and in each case one leg (15) of the folding sections (13) is oriented radially inwardly.

6. Implant according to claim 5, characterized in that the lattice structure (11) in the expanded state I is formed wave-shaped, wherein the wave height W in the expanded state I is smaller than in the folded state IL

7. Implant according to at least one of claims 1 to 6, characterized in that the folding means (12) comprise folding grooves (16) which are arranged in the longitudinal direction of the implant.

8. Implant according to claim 7, characterized in that the folding grooves (16) are arranged parallel to the longitudinal axis of the implant and / or spirally.

9. Implant according to claim 7 or 8, characterized in that the folding grooves (16) on the inside (17 a) and / or outside (17 b) of the grid structure (11) are formed.

10. Implant according to claim 9, characterized in that on the inside (17a) and the outside (17b) arranged folding grooves (16) are arranged offset from one another.

11. Implant according to at least one of claims 7 to 10, characterized in that the folding grooves (16) are formed in lattice webs (18), in particular in the region of connectors (19).

12. Implant according to at least one of claims 1 to 11, characterized in that the wall thickness of the wall (10) ≤ 70 μm, in particular <60 μm, <50 μm, <40 μm, ≤ 30 μm, ≤ 20 μm, ≤ 15 μm, ≤ 10 μm.

13. The implant according to claim 1, wherein the diameter of the implant in the expanded state is ≥ 2 mm, in particular> 3 mm,> 4 mm, ≥ 5 mm, ≥ 6 mm,> 7 mm , ≥ 8 mm, ≥ 9 mm, ≥ 10 mm.

14. An implant according to at least one of claims 1 to 13, characterized in that the folding means (12) comprise connectors (19) which connect at least two grid cells (14), the connectors (19) each having an S have shaped geometry.

15. An implant according to claim 14, characterized in that the connectors (19) each have a central portion (20a) for forming the S-shaped geometry and two outer portions (20b, 20c) connected to the central portion (20a) ), wherein the angle between an outer portion (20b, 20c), in particular between each one outer portion (20b, 20c) and the central portion (20a) <90 °, in particular <80 °, <70 °, <60 °, < 50 °, <40 °, <30 °, <20 °, <10 °.

16. An implant according to claim 14 or 15, characterized in that the central portion (20a) and at least one outer portion (20b, 20c), in particular both outer portions (20b, 20c) are arranged parallel to each other.

17. An implant according to at least one of claims 14 to 16, in that there are two circumferentially juxtaposed connectors (19) offset in the longitudinal direction.

18. An implant according to at least one of claims 1 to 13, characterized in that the folding means (12) comprise connectors (19) which each have two grid cells (14). connect, wherein the connectors (19) each have a circumferentially oriented U-shaped geometry.

19. A method for producing an implant according to claim 1, wherein the lattice structure (11) with folding means (12) is provided such that the lattice structure to form radially inwardly projecting folding sections from an expanded state I in a compressed folding state II can be transferred is.

20. The method according to claim 19, characterized in that the folding means (12), in particular folding grooves (16) are produced by etching, by sinking or wire erosion or by PVD or CVD deposition of a raw material on a mandrel with a groove profile corresponding to the negative profile ,

21. A method of introducing a medical implant having a lattice structure comprising lattice cells (14) deformable in the longitudinal direction of the implant into a delivery system in which a diameter of the implant is reduced such that the diameter is equal to or smaller than the inner diameter of the delivery system, wherein when reducing the diameter, the grid cells are first deformed, in particular partially deformed, and then folded radially inward.

22. A medical device, in particular for removing concretions from hollow organs of the body or for recanalizing hollow organs of the body, with a wall (10) curved at least in sections in the implanted state, comprising a lattice structure (11) with lattice cells (14), wherein the lattice cells (14) in the longitudinal direction of the implant are deformable such that the

Lattice structure (11) is flexible for adaptation to a vessel, the lattice structure (11) folding means (12) which are adapted such that the grid structure (11) for insertion into a feed system to form radially inwardly projecting folding sections ( 13) can be converted from an expanded state I into a compressed folded state II.