EP2142140A1

EP2142140A1 - Implant, method and device for producing an implant of this type

Info

Publication number: EP2142140A1
Application number: EP08734876A
Authority: EP
Inventors: Kirsi SCHÜSSLER
Original assignee: Acandis GmbH and Co KG
Current assignee: Acandis GmbH and Co KG
Priority date: 2007-03-30
Filing date: 2008-03-28
Publication date: 2010-01-13
Also published as: US20100256733A1; WO2008119520A1; DE102007015462A1

Abstract

The invention relates to an implant comprising a wall element (10), which when implanted comes into contact with a fluid, the wall element (10) being adapted to influence the flow behaviour of the fluid. The invention is characterised in that the wall element (10) has a non-continuous profile.

Description

"Implant and method and device for producing such an implant"

description

The invention relates to an implant and to a method and a device for producing such an implant. An implant with the features of the preamble of claim 1 is known, for example, from EP 1 153 581 A1.

The narrowing of vascular sections (restenosis) after stent implantation continues to be a major clinical problem despite numerous advancements in the field. It is generally recognized that neointimal hyperplasia is the main cause of restenosis following stent placement. Although the mechanisms responsible for the occurrence of restenosis have not yet been fully elucidated, damage to the endothelium and smooth muscle cells of the vessel wall due to stent implantation, reduced compliance through rigid stent structures, and shear stress change at the vascular wall (wall shear stress) of the stented vessel sections as a trigger for the neointimal hyperplasia and thus for restenosis.

In addition, it is known that the stented vessel sections not only lead to a change in the shear stress on the vessel wall, but also can promote the undesired formation of thrombi by changes in the hemodynamics of the natural blood flow. Furthermore, it is known that the formation of restenosis may be dependent on the stent geometry. In general, it is believed that low shear stress on the vessel wall promotes neointimal hyperplasia.

BESTÄTiGUNGSKOPia According to the above-mentioned EP 1 153 581 B1, a stent is proposed in this connection, in the interior of which a flow cylinder arranged centrally in the longitudinal direction of the stent is fastened. Due to the reduced flow diameter between the flow cylinder and the surrounding wall of the stent, the flow velocity in the stent is increased, so that adjusts a steeper flow profile near the wall. However, the attachment of the flow cylinder in the stent is problematic in terms of manufacturing technology. In addition, the flow cylinder affects the flexibility of the stent.

WO 03/1057328 discloses a braided multilayer stent having a core for influencing hemodynamics inside. Also with this stent it comes manufacturing problems.

The invention has for its object to provide an implant with a wall element that is relatively easy to manufacture and improved in terms of reducing restenosis after implantation. The invention further has the task of specifying a method and a device for producing such an implant.

According to the invention this object is achieved with respect to the implant by the subject-matter of claim 1, with regard to the method by the subject-matter of claim 9 and with respect to the device by the subject-matter of claim 11.

The invention is therefore based on the idea of specifying an implant with a wall element, which comes into contact with a fluid in the implanted state, wherein the wall element is adapted to influence a flow behavior of the fluid. According to the invention, the wall element is profiled discontinuously.

The invention uses a different approach than the stents, which cause a reduction in the effective flow diameter through a cylinder arranged in the flow channel. In the case of the implant according to the invention, the wall or a wall element is modified by a discontinuous profiling which influences the flow behavior. This has the advantage that no additional flow body, such as the flow cylinder, consuming connected to the wall Need to become. Rather, a cross-sectional constriction is achieved by the wall element itself by its discontinuous profiling.

The invention has the particular advantage that the shear stress on the vessel wall is increased by influencing the hemodynamics in the bloodstream, in particular by increasing the flow velocity, and thus inhibiting neointimal hyperplasia and restenosis. Furthermore, early endothelialization of the implant is promoted, which also has a positive effect, since it counteracts the occurrence of neointimal hyperplasia. Influencing the flow dynamics, in particular increasing the flow velocity, also inhibits the formation of thrombi.

Another advantage of the invention is that the implant is particularly well suited for the treatment of aneurysms. The narrow mesh size of aneurysm stents required to cover the aneurysm leads to negative side effects, such as restenosis and formation of thrombi. These undesirable side effects are avoided or at least less pronounced by the discontinuous profiling of the wall element.

The invention is not limited to stents, in particular intraluminal stents, but generally includes implants, in particular medical or endovascular implants, which are impinged by a fluid, or generally have a flow control function, such as stent grafts, protection filter etc.

In a preferred embodiment, the wall element on profile elements with discontinuously arranged inflow surfaces. The inflow surfaces are not connected to each other continuously, but generally have abrupt transitions, so that the overall result is a discontinuous profile or a discontinuous contouring of the inside of the wall element. Such a wall element or an implant with such a wall element can be produced easily and with comparatively low costs.

A particularly effective influencing of the flow behavior is achieved when the inflow surfaces have a main orientation which extends substantially in the flow direction. The inflow surfaces can, with respect to the wall element, in each case be inclined and / or convexly curved and / or concavely curved. Due to the different design of the inflow, a different influence on the flow behavior can be adjusted.

In a preferred embodiment, the discontinuous profiling of the wall element is achieved in that the inflow surfaces each have an end remote from the wall element, in particular a free end, which protrudes in the implanted state in the fluid flow. In this case, the profile elements can form a profile of the wall element that is serrated in cross-section. Such a cross-sectional profile can be produced in a simple manner.

The profile elements may form a pattern, in particular a helical pattern. The pattern formation ensures that a desired flow behavior is impressed on the fluid over a longer flow path.

The wall element may comprise a grid structure with grid elements, such as webs, end bends, connectors and the like, wherein at least some of the grid elements for forming the leading surfaces are each arranged in a different plane than an inner surface of the wall element. This design is particularly suitable for stents and is characterized by a production-friendly construction. There are no additional separate elements required to be connected to the stent to form a wall profile. Rather, the discontinuous profile is formed by the already existing grid elements, which are modified such that they are each arranged in a different plane than the inner surface of the wall element. The inner surface of the wall element is therefore not continuous, but generally has a discontinuous profiled contour.

The method according to the invention for producing such an implant is based on the fact that the wall element is profiled intermittently to influence the flow behavior of a fluid which comes into contact with the wall element in the implanted state. For this purpose, the wall element can be locally deformed such that discontinuously arranged inflow surfaces of the profile elements are formed.

To produce such an implant, a device is proposed according to the invention which has a shaped part with a discontinuously profiled contour. The invention will be explained below in greater detail by means of embodiments with reference to the attached schematic drawings.

In this show

1 shows a cross section through a conventional implant without profiling, which is arranged on a forming tool.

2 shows a cross section through an implant according to an inventive

A discontinuous profiling embodiment disposed on a modified forming tool;

3 shows a schematic cross section through an implant according to an embodiment of the invention in the implanted state. and

Fig. 4 is a plan view of the implant according to FIG. 3 (detail).

In Fig. 1, a conventional tubular stent is shown, which is arranged on a cylindrical mandrel as a shaping tool. In this conventional stent, the design elements, for example, the webs lie on a cylindrical surface and form a wall element 10 with an inner surface 10a and an outer surface 10b. The inner surface 10a forms or delimits a flow channel through which blood flows in the implanted state. The outer surface 10b abuts against the vessel wall in the implanted state and supports it. As can be seen from FIG. 1, the inner surface 10a forms a flat, non-profiled lateral surface. This means that all design elements (lands, connectors, end curves) in the same plane, i. are arranged in the lateral surface formed by the inner surface 10a.

In contrast to this, the design elements or grid elements 14a of the implant according to FIG. 2 are arranged in a different plane than the inner surface 10a of non-profiled wall sections in such a way that the wall element 10 is profiled discontinuously. The grid elements 14a form profile elements 11 with inflow surfaces 12 bτ>μ>. Deflection surfaces for deflecting the fluid flow in the implanted state. While the inner surface 10a of the stent according to FIG. 1 extends parallel to the longitudinal axis of the stent, the inner surface 10a of the implant according to FIGS. 2 to 4 is not arranged in sections parallel to the longitudinal axis. In particular, inner surface 10a is partially inclined or employed. This is achieved in that at least some of the grid elements 14a are moved out of the original lateral surface of the implant (see FIG. This results in the discontinuous profiling of the wall element 10, wherein at least some grid elements 14a sections form the original, non-profiled lateral surface of the wall element 10 and some grid elements 14a protrude from the non-profiled lateral surface sections. The grid elements 14a are only available so far that a, although formed with a reduced flow diameter flow channel is open.

The respective inner surface 10 a of the protruding grid elements 14 a acts as inflow or deflection surface 12 for the fluid flow. The inflow surfaces 12 of the various grid elements 14a and the profile elements 11 are arranged discontinuously and at least in the profile space, i. interrupted outside the unprofiled original lateral surface. This generally results in an abrupt or discontinuous transition between the profile elements 11.

In Fig. 3, the discontinuous shape of the wall profile is clearly visible, wherein the profile elements 11 have peaks or ends 13 which protrude into the flow channel. As can be seen with reference to FIG. 4, the ends 13 correspond to the end curves 16, which respectively connect adjacent webs 15. The ends 13, and the end bends 16 are in the implanted state of the sections not profiled wall sections or of the wall sections, which mainly fulfill a support function in the implanted state, arranged radially inwardly spaced. In addition to the radially inwardly projecting lattice elements 14a, it is also possible to provide radially outwardly projecting lattice elements 14a, through which improved anchoring of the stent in the surrounding tissue is achieved.

The inflow surfaces 12 have a main or preferential orientation, which extends substantially in the flow direction, as shown by the arrow S in Fig. 3. This means that the inflow surfaces 12 are set in the same direction and thus all have a substantially identical angle of inclination. In this case, the inflow surfaces 12, or the associated grating elements 14a may be inclined, the inflow surfaces 12 themselves being straight or flat, as shown in FIG. Age- natively or additionally, the inflow surfaces 12, or the associated grating elements 14a may be concavely or convexly curved. In addition, different angles of inclination for individual inflow surfaces 12 or different radii of curvature can be set. The grid elements 14a are unidirectionally inclined or curved in the flow direction. Different geometry properties can be combined with each other, in particular combined in a pattern.

In Fig. 4, the lattice structure 14 of the stent according to the embodiment of the invention is particularly well recognizable. The lattice structure 14 comprises webs 15, wherein at least some of the webs 15 or, in general, some of the web elements 14a for forming the inflow surfaces 12 are each arranged in a different plane than an inner surface 10a of the wall element 10 in a non-profiled region. In order to form the discontinuous profiling, at least two webs 12 arranged downstream in the direction of flow S are bent radially inward with their end bends 16 or ends 13 or generally grid elements 14 a or protrude radially inwards. This means that the radially inwardly bent webs 12 and Endbögen.16 protrude in the implanted state in the flow channel of the stent. The transverse to the flow direction S, i. in the circumferential direction adjoining or adjacent end curves 16a, 16b are located in the original cylindrical shell plane of the stent and form a non-profiled region of the wall element 10. This means that the adjacent end curves 16a, 16b in the image plane and the end bend 16 arranged therebetween are arranged outside the image plane of Fig. 4. In this way, a discontinuous profiling of the wall element is achieved, wherein the non-profiled regions and the discontinuously profiled regions are arranged in different planes. The non-profiled regions are determined by the grating elements 14a arranged in the original lateral surface, in particular the end curves 16a, 16b. The discontinuously profiled regions are formed by the bent or projecting grid elements 14a, in particular the webs 12 and end bends 16.

In other words, the inner surfaces 10a of the profiled and non-profiled regions of the wall element 10 form intersecting planes. The profile elements 11 are part of the wall element 10 in the present example and differ from the wall element 10 by the inwardly projecting or exposed position or arrangement.

The deformation, ie the bending of the grid elements 14 a can take place in the region between two webs 15 bounding end curves 16, 16 a, wherein the web 15 in the Near one of the two end curves or, for example, in the middle of the web is bent, depending on how large the inflow area 12 thereby achieved should be.

This principle is applicable to the entire stent, with various patterns, for example a helical or spiral pattern, by appropriate placement of the profiling, i. the bent elements can be achieved. The profiling extends over a certain length or partial length of the stent.

The hollow cylindrical overall shape of the stent is retained.

Overall, the profile elements 11 form local and discontinuously arranged constrictions of the flow diameter of the implant in the implanted state.

For producing the implant or the stent according to FIGS. 2 to 4, the wall element 10 is at least partially moved out of the surface originally formed by the wall element 10. This can be, for example. be done by., That s_die webs 15 are bent radially inwardly and / or radially outward. This ensures that the individual webs 15 are made relative to the original cylindrical lateral surface of the stent. This is expediently carried out by a shaping tool 18 according to FIG. 2, which has a correspondingly profiled mandrel. The forming tool 18 according to FIG. 2 is at least two-parted and has an inner part 18b and an outer part 18a. The outer profile of the inner part 18b and the Innenprofϊl the outer part 18a are complementary, so that the shaping tool in the assembled state has a profile corresponding to the employee of the implant.

The wall element 10 or the implant can preferably be produced from a shape memory material, such as Nitinol. This has the advantage that the wall element 10 in the compressed state of the implant can be forced into the same area as the other grid elements 14a, which in the expanded state are responsible for the discontinuous profiling of the wall element. The implant can thus be constructed without an additional enlargement of the insertion diameter. The three-dimensional structure produced by the wall element in the expanded state (compared to the two-dimensional structure of the non-profiled wall element) is reduced to the previous two-dimensional shape during insertion of the stent by the use of a shape memory material for the wall element 10. LIST OF REFERENCE NUMBERS

10 wall element

10a inner surface

10b outer surface

11 profile elements

12 flow surfaces

13 end

14 grid structure

14a grid elements

15 bars

16 end curves

17 connectors

18 shaping tool

18a outdoor unit

18b inner part

Claims

claims

1. implant with a wall element (10), which comes into contact with a fluid in the implanted state, wherein the wall element (10) is adapted to influence a flow behavior of the fluid, characterized in that the wall element (10) is profiled discontinuously.

2. Implant according to claim 1, characterized in that the wall element (10) profile elements (11) with discontinuously arranged inflow surfaces (12).

3. Implant according to claim 2, characterized in that the inflow surfaces (12) have a main orientation which extends essentially in the flow direction.

4. Implant according to claim 2 or 3, characterized in that the inflow surfaces (12) relative to the wall element (10) are each inclined and / or convexly curved and / or arranged concavely curved.

5. Implant according to at least one of claims 2 to 4, characterized in that the inflow surfaces (12) each have a wall element (10) spaced end (13), in particular a free end (13), in the implanted state in the fluid flow protrudes.

6. Implant according to at least one of claims 2 to 5, characterized in that the profile elements (11) form a sawtooth-shaped profile of the wall element (10) in cross section.

7. Implant according to at least one of claims 2 to 6, characterized in that the wall element (10) comprises a grid structure (14) with grid elements (14a), wherein at least some of the grid elements (14a) for forming the leading surfaces (12) respectively in a different plane than an inner surface of the wall element (10).

8. Implant according to at least one of claims 2 to 7, characterized in that the profile elements (11) form a pattern, in particular a helical pattern.

9. A method for producing an implant with a wall element (10), wherein the wall element (10) for influencing the flow behavior of a fluid which comes into contact with the wall element (10) in the implanted state, is discontinuously profiled.

10. The method according to claim 9, characterized in that the wall element (10) for forming profile elements (11) with discontinuously arranged inflow surfaces (12) is locally deformed.

11. A device for producing an implant with a wall element (10) having a molded part, which has a discontinuously profiled contour.