JP2020036965A - Stent - Google Patents

Abstract

To provide a stent that reliably precludes kinking upon deployment.SOLUTION: The invention relates to a stent for transluminal implantation in hollow organs, in particular in blood vessels, ureters, esophagi, colons, duodena, or bile ducts. The stent comprises a substantially tubular body which can be transferred from a compressed state having a first cross-sectional diameter to an expanded state having an enlarged second cross-sectional diameter. The stent comprises a plurality of cells which are defined by bordering elements 22 formed by the tubular body. The stent is distinguished in that some of the cells are extended in the longitudinal direction of the stent in comparison with the remaining cells in order to form a slanted end face of the stent.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a stent for transluminal implantation into a hollow organ, particularly a blood vessel, ureter, esophagus, colon, duodenum or biliary tract, wherein the stent has a second cross-sectional diameter expanded from a compressed state having a first cross-sectional diameter. A stent comprising a substantially tubular body capable of being deformed into an expanded state having a plurality of cells defined by boundary elements formed by the tubular body.

  This type of stent is used for reopening pathologically altered hollow organs. In this regard, the stent is introduced in a compressed state via a delivery catheter into a location within the hollow organ to be treated, expanded at different sizes to a diameter corresponding to the diameter of a healthy hollow organ, and expanded into a hollow organ, e.g. A vessel wall retention effect is achieved.

  Such a stent can be manufactured, for example, such that a plurality of slit-like openings are cut into the wall of the tubular body to form a plurality of diamond-shaped openings when the stent is expanded. The boundary element together with the opening is called a cell.

  If the stent is to be inserted near the bifurcation of a hollow organ, a stent having a chamfered or chamfered end formed into a generally smooth contour can be used. Such a stent makes it possible to support a blood vessel, for example a vein, on all sides up to the bifurcation, for example, to the opening of a further vein.

  To ensure their retention effect, stents must be able to exert sufficient radial alignment force to counteract the effects of the radial forces exerted by the vessel wall. The alignment force is applied, especially in the region of the chamfered edge, as the radial placement force is typically reduced there.

  Accordingly, it is an object of the present invention to provide a first type of stent that also provides a high radial deployment force in the chamfered area, thereby ensuring that the twist during deployment of the stent is eliminated. is there.

  The object of the invention is achieved by a stent according to the invention having the features of claim 1, in particular wherein some cells are elongated in the longitudinal direction of the stent compared to the remaining cells, Is achieved by forming a chamfered front end.

  The chamfered edge may be formed by an elongated cell. In this regard, with the elongated cells extending in the longitudinal direction, no additional cells are required to form the chamfered edge. The elongated cells also allow a similar arrangement of cells in the chamfered area to be selected, as well as other tubular bodies.

  The elongate cells can only be present, in particular, in the rigid part of the stent. In addition, the stent includes, for example, a flexible portion and / or a fixing portion that is flexible. The following description of the elongated cells relates to the rigid part.

  Avoidance of additional cells results in a stent structure that can provide high deployment forces, especially in the radial direction. In this way, for example, it is possible to reliably support a blood vessel near the bifurcation. Thus, the stent according to the invention can be inserted into the inferior vena cava in the region of the bifurcation, for example in the case of a venous occlusion at the junction of the common iliac veins, in the region above the common iliac veins. The stent can have a diameter of 12 mm or more for this purpose. The stent can preferably have a diameter between 12 mm and 18 mm.

  The distribution with additional cells further allows to variably fix the chamfer angle. That is, this angle can be fixed by the relative extension of the elongated cells.

  The chamfered region makes it possible to ensure that the hollow organ as a whole is supported up to the bifurcation without substantially protruding into the blood vessel after the bifurcation.

  A cell can be connected to one or more other cells by one or more connections. The length of the cell can be understood as the longitudinal spacing between two connections and the respective center of each connection needs to be considered. The cell includes the cuts and their respective border elements, and the connection belongs to the border elements.

  In the stent according to the present invention, at least some of the cells can be connected to each other using the plurality of connection portions. Three or four respective connections may in particular be provided in the chamfered area and / or in the elongated cells. Thus, the holding effect can be particularly high because of the radial positioning forces that can be achieved in this way.

  Stents can be manufactured from memory metals that employ storage configurations that are above the critical temperature.

  Preferred embodiments of the invention can be taken from the description, the dependent claims and the drawings.

  According to a first advantageous embodiment, at least some of the elongate cells are arranged in particular along a straight line or a substantially straight line extending parallel or substantially parallel to the longitudinal direction. This means that, for example, at least one or two cells can be provided which are arranged in a straight line with one another. For more than two cells, at least two connections of at least one of these cells can be directly connected to extension cells of two further cells. The two respective connections of the elongated cell are in particular straight.

  According to a further advantageous embodiment, the elongate cells can be divided into a plurality of groups, in particular nine groups, wherein the cells of each group are respectively arranged along a straight line or a substantially straight line, these straight lines being longitudinally It is parallel or almost parallel to the direction. A total of 12 groups of cells can be provided, with 9 groups having stretched cells. With the definition of such groups, the intermediate spaces between the groups can themselves form cells.

  Thus, the arrangement of the cells can be selected such that each cell is arranged along a straight or substantially straight line. Further, cells can be formed symmetrically with respect to one of these systems. Thus, in particular, no cells are tilted or rotated with respect to other cells. In this manner, the weakened structure due to the rotated cell can be avoided.

  All the cells in a group, in particular, can each have the same or substantially the same length in the longitudinal direction. Alternatively, cells having different lengths can be provided in the group.

  The lines formed by the different groups of cells preferably extend parallel or substantially parallel to each other.

  Each equal amount of cells is more preferably provided in each group from a cross-sectional plane extending perpendicular to the longitudinal axis to the chamfered front end. Radial deployment force can be achieved by providing an equal number of cells each in groups that are substantially constant over the length of the stent. The same number of cells can preferably be provided for each group of rigid portions of the stent.

  The respective angles that can be perceived in the so-called flat projection of the stent can be formed in particular by the connection of the cells when using the same number of cells. The angle is determined by the circumferential direction (ie, the straight line in the flat projection) and the straight line, which extends through the connection of the cell. This means that at least some connections of each cell lie on a straight line in a flat projection. The angle increases as it approaches the chamfered end of the stent, and preferably four, five, or six angles are set.

  The ends of the cell cannot form a straight line in the flat projection of the chamfered end itself, but can define a curve that approximates a sinusoid. Such a sinusoid in a flat projection results in an inclined starting cut (chamfered area) with a precisely planar cutting surface in a three-dimensional stent.

  The cell has a first angle in the range of 20 ° to 24 °, a second angle in the range of 37 ° to 44 °, a third angle in the range of 48 ° to 52 °, and a fourth angle of the cell. Is in the range between 60 ° and 64 °, the fifth angle is in the range between 63 ° and 67 °, and the sixth angle is in the range between 69 ° and 73 °. It is composed of The largest angle is particularly closest to the chamfered end of the stent, and the smallest angle is furthest from the chamfered end. Furthermore, an angle of 0 ° can be provided. This means that the location of the stent is in a flat projection where the connections are arranged along the circumferential direction. An angle of 0 ° can be provided when changing from a rigid part to a flexible part (from a hard region to a flexible region). The cells of the group can be of different lengths to form the described angles.

  It has been found that such a choice of angle can produce a very stable stent with particularly long durability.

According to a further advantageous embodiment, the length of the cells of the neighboring groups decreases from a maximum to a minimum in the circumferential direction. The cell with the largest length is in particular arranged opposite the cell with the smallest length with respect to the central axis of the stent. Such an arrangement can create a chamfer.

  It is further preferred that at least some of the cells are connected to one another by connections, wherein only the connections between the elongated cells, especially between the longest cells, are elongated. The longest cell opening can be shortened by an elongated or enlarged connection so that a uniform curved opening of all cells can be achieved upon stent expansion. Such a uniform curved opening can in turn lead to a uniform distribution of the radial deployment forces and in particular to a robust stent.

  The at least one marker preferably extends in a longitudinal direction away from the chamfered end, in particular in the form of an eyelet or eyelet, the marker having an asymmetric shape. The marker may be a part of the stent that has increased radiopacity, ie, is particularly easily visible on x-rays. The marker may in particular be, for example, an eyelet that is filled with or covered by tantalum. Markers can also be mounted in the chamfered area due to the asymmetric shape. This is because the marker can extend away from the chamfer.

  In other words, the markers can be located in the region between the longest and shortest of the stent in the longitudinal direction. The markers can be designed large enough for asymmetric shapes so that they are particularly easily recognized on X-rays. Further, additional markers can be provided. At the tip of the chamfer. Yet another marker may be attached to the chamfer at the shortest point of the stent, for example.

  According to a further advantageous embodiment, at least two asymmetric markers are provided at the chamfered end, in particular the markers are arranged opposite one another with respect to the axis of the stent. Thus, the two markers may be symmetrically disposed with respect to the plane of the stent extending through the axis of the stent and the tip of the chamfer. Asymmetric markers can be aligned in X-ray for such placement, for example. As a result, the position of the stent is particularly easily recognized by X-ray.

  According to a further advantageous embodiment, the stent comprises a flexible part adjacent to the rigid part. The flexible portion is arranged to face the chamfered end. The flexible portion can have cells that have a larger area in flat projection than the cells of the rigid portion. The flexible part can be bent more easily due to the larger cells, so that the flexible part can be adapted in a simple manner to the shape of a hollow organ. The cells of the flexible part may have preferably tooth-like boundaries.

  According to yet another advantageous embodiment, a stent includes a fixation portion adjacent to a flexible portion. The cells of the fixed part can correspond to the cells of the rigid part and can be, for example, rhombic. The anchor can have a small flexibility due to the diamond-shaped cells and can anchor the stent in its position in the hollow organ. The anchor may form a straight end of the stent to which a marker extending away from the end of the stent may be attached. The marker may have the shape of an eyelet, as well, for example, covered or filled with tantalum. When the stent is introduced into the hollow organ, the stent can be fixed in the delivery catheter using the marker of the fixing portion.

The invention further relates to a method of manufacturing a stent, the method comprising:
a) the stent is cut from a tubular material, and
b) The stent is expanded to its expanded state. The method of the invention is characterized in that c) the shape of the cells of the stent is changed and fixed in the expanded state.

  The individual cells can each be shaped such that uniform expansion behavior of the individual cells is achieved by changing the shape of the cells. In this way, the risk of breakage can be particularly reduced in short and medium sized cells near the chamfered area, which are typically asymmetric and overexpanded due to uneven force distribution during expansion.

  For example, the acute angle can be reduced or changed such that a diamond cell having up to four connections at each corner of the diamond is less than 70 °, preferably less than 60 °. This results in the stent being better able to withstand greater external forces in the region of the chamfered region due to structurally uniform force dissipation, and the risk of stent collapse or stent breakage is significantly reduced.

  Furthermore, by using this method, it is possible to prevent the cell expansion from becoming too large, thereby avoiding damage to the connections.

  According to an advantageous embodiment, the core to which the fastening means is attached is used for expanding the core to change and fix the shape of the cells of the stent. Thus, the expansion behavior of the individual cells can be adapted by the fastening means. As a result, the shape of the cell changes with the expansion in use of a purely cylindrical core. Such a cylindrical core may also include a conical portion that facilitates tensioning the stent. Further, expansion can occur while supplying heat.

  The fastening means is particularly preferably a needle or mandrel which is introduced into a hole in the core. The needle or mandrel can, for example, be moved out of the core from the inside or can be inserted into the core from the outside. For this purpose, for example, an automatic process can be performed using a robot or a hydraulic system, but also a manual application of the cell can be performed.

  According to a further advantageous embodiment, the altered shape of the cells of the stent is permanently fixed by a heating process. Such a fixation is particularly advantageous for the use of a memory metal which adopts the shape stored by the heating process when the temperature rises. Permanent fixation is understood to mean that the shape of the cells of the stent in the expanded state of the stent is fixed while the shape of the cells is maintained in the expanded state even if the stent is temporarily changed to the compressed state. Should. When the stent is introduced into the body, the stent and its cells can regain the shape taught during the manufacturing process due to the heat of the body.

  The present invention is described below with reference to advantageous embodiments and the accompanying drawings.

1 is a side view showing an expanded state of a stent according to the present invention. FIG. 2 is a plan view showing the stent of FIG. 1 in an expanded state. FIG. 2 is a cutaway view of the stent of FIG. 1 projected onto a plane. FIG. 4 is a cutaway view of FIG. 3 with an illustration of an angle defined by a connection.

  1 and 2 show a stent 10. The stent 10 has a tubular design and includes a rigid portion 12, a flexible portion 14 adjacent to the rigid portion 12, and a fixing portion 16 adjacent to the flexible portion 14.

  The rigid part 12 is formed from diamond-shaped (closed) cells 18 connected to other diamond-shaped cells 18 via three or four connection parts 20, respectively. The diamond-shaped cells 18 are defined by web-like border elements 22 formed from metal.

  The rigid portion 12 includes a chamfered region 24 that allows the stent 10 to be used at the bifurcation (not shown) of the hollow organ.

  The chamfered region 24 forms the end of the stent 10 and is configured such that some of the rhombic cells 18 are elongated in the longitudinal direction L. The longest diamond-shaped cell 18 is indicated by reference numeral 18a in the drawing. The shortest diamond-shaped cell 18 is indicated by reference numeral 18b. The hard portion 12 is provided with three shortest rhombic cells 18b and three longest rhombic cells 18a in the longitudinal direction L. The longest diamond cell 18 is located at this point on the opposite side of the short diamond cell 18b with respect to the central axis of the stent 10. Three groups of longest and shortest rhombic cells 18a, 18b are provided adjacent to each other (ie, adjacent in the circumferential direction).

  Open cells 26 having a saw-tooth or tooth-like profile are arranged in the flexible part 14, and fewer open jagged tooth cells 25 are provided as rhombic cells 18 when viewed in the circumferential direction of the stent 10. The flexible portion is more easily deformable with respect to the longitudinal direction L, due to the use of fewer open serrated cells 26, and thus can be easily adapted to the length of the blood vessel or the like.

  The anchor 16 is formed by diamond shaped cells 18 that increase the rigidity of the anchor 16, ensuring that the stent 10 maintains its position within the hollow organ.

  Four respective eyelet-shaped markers 28 are provided on both the chamfered area 24 and the end of the stent formed by the anchors (three are each visible in FIG. 1). All four markers 28 in the chamfered area 24 can be seen in FIG.

  The two markers 28 attached to the longest and shortest points of the stent 10 in the chamfered area 24 are formed symmetrically. Two more markers 28 are attached to the chamfered area 24 having the average length of the stent 10. These two markers 28 are formed as asymmetric marks 28a, the area of the asymmetric markers 28a extending towards the shortest area of the stent.

  FIG. 3 shows the rigid portion 12 of the stent 10 of FIGS. 1 and 2 in a so-called cutaway view. As a result, FIG. 3 shows the projection of the in-plane cut introduced into the stent material. Thus, the line indicates a break. To form the diamond shaped cells 18 shown in FIGS. 1 and 2, a plurality of straight cuts extending parallel and offset from each other when the stent 10 is expanded can be provided.

  The area of material, shown as a white area and lying between the lines, becomes a connection 20 or a boundary element 22 after expansion. FIG. 3 shows only the rigid portion 12 of the stent 10.

  In FIG. 3, it can be seen that an extension connection 20a is provided between the longest rhombic cells 18a, creating a more uniform curved opening of all rhombic cells 18 upon expansion of the stent.

  FIG. 4 shows the view of FIG. 3 with the angle of incidence formed by the connection 20 having a circumferential direction. Six angles α1, α2, α3, α4, α5, α6 are shown, which are from an angle of about 22 ° (α1) to about 40 ° (α2), 50 ° (α3), 62 ° (α4) and 65 °. Over the angle of ° (α6), it continuously increases to an angle of about 71 ° (α6). A straight end line 30 located at the transition from the rigid region 12 to the flexible region 14 extends circumferentially through the connection 20 and thus defines an angle of 0 °.

Reference Signs List 10 stent 12 rigid part 14 flexible part 16 fixing part 18, 18a, 18b rhombic cell 20, 20a connecting part 22 boundary element 24 chamfered area 26 open serrated cell 28, 28a marker 30 end line L longitudinal direction α angle

Claims (4)

A method for manufacturing a stent (10), comprising:
a) said stent (10) is cut from a tubular material;
b) expanding the stent (10) to its expanded state;
c) The method characterized in that the cells (18, 18a, 18b) of the stent (10) are reshaped and fixed in the expanded state.   2. The stent according to claim 1, wherein a core is used for the expansion to which a fastening means is attached, and the cells of the stent are changed in shape and fixed in the expanded state. 3. the method of.   The method according to claim 1 or 2, wherein the fastening means is a needle or a mandrel introduced into a hole in the core.   4. The method according to claim 2, wherein d) the changed shape of the cells (18, 18a, 18b) of the stent (10) is permanently fixed by a heating process.

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