JP6852142B2 - Stent - Google Patents

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, with a second cross-sectional diameter expanded from a compressed state having a first cross-sectional diameter. With respect to a stent comprising a substantially tubular body capable of transforming into an expanded state having and containing a plurality of cells defined by a boundary element formed by the tubular body.

This type of stent is used for recanalization of pathologically altered hollow organs. In this regard, the stent is introduced in a compressed state through a delivery catheter into a position within the hollow organ to be treated and expanded to a diameter corresponding to the diameter of a healthy hollow organ, with a hollow organ, eg, a hollow organ, eg. The retention effect of the vessel wall is achieved.

Such a stent can be manufactured, for example, so 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 inserted near the bifurcation of a hollow organ, a stent with an overall smooth outer shelled end or chamfered end can be used. Such a stent makes it possible to support a blood vessel, eg, a vein, on all sides up to bifurcation, eg, to an additional vein opening.

To ensure their retention effect, the stent must be able to exert sufficient radial alignment to counteract the effects of radial forces exerted by the vessel wall. Alignment forces are applied, especially in the area of the chamfered edges, as radial placement forces typically diminish there.

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

An object of the present invention is achieved by the stent of the present invention having the characteristics of claim 1, in particular, some cells are elongated in the longitudinal direction of the stent as compared to the remaining cells, and the stent. This is achieved by forming the chamfered front end of the.

The chamfered end can be formed by elongated cells. At this point, the elongated cells extending in the longitudinal direction do not require additional cells to form the chamfered edges. The elongated cells also allow the choice of similar placement of cells within the chamfered area, as with other tubular bodies.

The elongated cell can be present only in the rigid rigid portion of the stent, in particular. In addition, the stent comprises, for example, a flexible flexible portion and / or a fixed portion. The following description of the elongated cell relates to a rigid portion.

Avoidance of additional cells results in a stent structure that can provide a particularly high radial placement force. In this way, for example, it is possible to reliably support the blood vessel near the bifurcation. Thus, the stent according to the invention can be inserted into the inferior vena cava in the area of the bifurcation, eg, in the case of venous occlusion at the confluence of the common iliac vein, in the upper area of the common iliac vein. The stent can have a diameter of 12 mm or more for this purpose. The stent can preferably have a diameter of 12 mm to 18 mm.

Distribution by additional cells makes it possible to fix the chamfer angle variably. That is, this angle can be fixed by the relative elongation of the elongated cells.

The chamfered area allows the hollow organ to be reliably supported to the bifurcation as a whole, with virtually no protrusion into the vessel after 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 the two connections, and it is necessary to consider the respective center of each connection. The cell includes the cut portion and its respective boundary element, and the connection portion belongs to the boundary element.

In the stent according to the present invention, at least a part of cells can be connected to each other by using a plurality of connecting portions. Each of the three or four connections may be provided, in particular, in the chamfered area and / or elongated cells. Therefore, the holding effect can be particularly high due to the radial placement force that can be achieved in this way.

The stent can be manufactured from a storage metal that employs a storage shape above the critical temperature.

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

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

According to a further advantageous embodiment, the elongated cells can be divided into a plurality of groups, particularly nine groups, the cells of each group are arranged along a straight line or a substantially straight line, and these straight lines are longitudinal. Parallel or substantially parallel to the direction. A total of 12 groups of cells can be provided, with 9 groups having elongated cells. With such group demarcation, the intermediate space between the groups can itself form a cell.

Therefore, the cell arrangement can be selected so that each cell is arranged along a straight line or a substantially straight line. In addition, cells can be formed symmetrically with respect to one of these lines. Therefore, in particular, there are no cells that are tilted or rotated with respect to other cells. In this way, it is possible to avoid the weakening of the structure due to the rotated cell.

All cells in the 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 within the group.

Lines formed by different groups of cells preferably extend parallel to or substantially parallel to each other.

More preferably, equal amounts of cells are provided in each group from the cross-sectional plane extending perpendicular to the longitudinal axis to the chamfered front edge. Radial placement forces can be achieved by providing an equal number of cells each within a group that is substantially constant over the length of the stent. The same number of cells can preferably be provided in each group of rigid portions of the stent.

Each angle that can be recognized in the so-called flat projection of the stent can be formed, in particular by the cell connections 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 cell connections. This means that at least some of the connections in each cell are on a straight line in a flat projection. The angle becomes larger as it approaches the chamfered end of the stent, and preferably 4, 5, or 6 angles are set.

The end 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 sinusoidal curve. Such a sinusoidal curve in a flat projection results in an inclined starting cut (chamfered region) with an exactly planar cut surface in a 3D 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. The angle 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 closest, especially to the chamfered edge of the stent, and the smallest angle is farthest from the chamfered edge. Further, an angle of 0 ° can be provided. This means that the position of the stent is present in a flat projection where the connections are arranged along the circumferential direction. The 0 ° angle can be provided when changing from a rigid portion to a flexible portion (from a rigid region to a flexible region). The cells of the group can be of different lengths to form the stated angles.

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

According to a further advantageous embodiment, the cell lengths of adjacent groups decrease from maximum to minimum in the circumferential direction. The cell with the maximum length is arranged, in particular, facing the cell with the minimum length with respect to the central axis of the stent. A chamfer can be generated by such an arrangement.

It is more preferred that at least some of the cells are connected to each other by a connection, with only the connections between elongated cells, especially between the longest cells, being formed elongated. The opening of the longest cell can be shortened by an elongated or enlarged connection so that a uniform curved opening of all cells can be achieved during stent expansion. Such a uniform curved opening can provide a uniform distribution of radial placement forces and a particularly robust stent.

The at least one marker preferably extends longitudinally away from the chamfered end, especially in the form of an eyelet or needle hole, and the marker has an asymmetric shape. The marker can be a portion of the stent that is more opaque to X-rays, i.e., which is particularly readily visible on X-rays. The marker can be, in particular, an eyelet that is filled with or covered with tantalum, for example. The marker can also be attached to the chamfered area due to its asymmetrical shape. This is because the marker can extend away from the chamfer.

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

According to a further advantageous embodiment, at least two asymmetric markers are provided at the chamfered end, in particular the markers are located opposite each other with respect to the axis of the stent. Thus, the two markers can be placed symmetrically 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-rays, for example, for such placement. 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 portion adjacent to the rigid portion. The flexible portion is arranged so as to face the chamfered end portion. The flexible portion can have cells that have a larger area in flat projection than the cells in the rigid portion. The flexible portion can be bent more easily due to the larger cell, whereby the flexible portion can be easily adapted to the shape of the degree of the hollow organ. The flexible cell can preferably have a dentate boundary.

According to yet another advantageous embodiment, the stent comprises a fixation portion adjacent to the flexible portion. The cell of the fixed portion can correspond to the cell of the rigid portion, and can be formed into a rhombus, for example. The fixation part can have a small flexibility due to the diamond-shaped cell, and the stent can be fixed in its position in the hollow organ. The fixation can form a straight end of the stent to which a marker extending away from the end of the stent can be attached. Markers can have the shape of eyelets and are likewise covered or filled with tantalum, for example. The stent can be secured within the delivery catheter using a marker at the fixation site when the stent is introduced into the hollow organ.

The present invention further relates to a method of making a stent, which method is:
a) The stent is cut out of a tubular material and
b) The stent is expanded to its expanded state. The method of the present invention is characterized in that c) the shape of the cell of the stent is changed and fixed in an expanded state.

The individual cells can be individually shaped so 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 for short and medium sized cells near the chamfered region, which are typically asymmetric and overextended due to the non-uniform force distribution during expansion.

For example, the acute angle can be reduced or modified so that the rhombic cell with up to four connections at each corner of the rhombus is less than 70 °, preferably less than 60 °. This results in the stent better tolerating greater external forces in the area of the chamfered area due to structurally uniform force dissipation, significantly reducing the risk of stent collapse or stent breakage.

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

According to an advantageous embodiment, the core to which the fastening means is attached is used to spread the core to change the shape of the stent cell and fix it. Therefore, the expansion behavior of individual cells can be adapted by fastening means. As a result, the shape of the cell changes with respect to expansion when using a purely cylindrical core. Such a cylindrical core can also include a conical portion that facilitates pulling of the stent. In addition, expansion can occur while supplying heat.

The fastening means is particularly preferably a needle or mandrel introduced into the hole in the core. The needle or mandrel can, for example, move from the inside to the outside of the core, or can be plugged into the core from the outside. For this purpose, for example, automated processes can be carried out using robots or hydraulic systems, but manual applications of cells can also be carried out.

According to a further advantageous embodiment, the altered shape of the stent cell is permanently fixed by the heating process. Such immobilization is particularly advantageous for the use of storage metals that employ a shape stored by the heating process as the temperature rises. Permanent fixation is understood to mean that the shape of the stent's cell in the expanded state of the stent is fixed while the shape of the cell is maintained in the expanded state even if the stent is tentatively changed to the compressed state. Should be. 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 will be described below with reference to advantageous embodiments and accompanying drawings.

It is a side view which shows the stent by this invention in an expanded state. It is a top view which shows the stent of FIG. 1 in the expanded state. It is a cut view which projected the stent of FIG. 1 on a plane. FIG. 3 is a cut view of FIG. 3 with an example of an angle defined by a connection.

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

The rigid portion 12 is formed from a diamond-shaped (closed) cell 18 connected to each of the other diamond-shaped cells 18 via three or four connecting parts 20. The diamond-shaped cell 18 is defined by a spider web-shaped boundary element 22 formed of metal.

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

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

The flexible portion 14 is provided with open cells 26 having serrated or toothed contours, with less open jagged toothed cells 25 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 a smaller number of open serrated cells 26, and thus can be easily adapted to the length of blood vessels and the like.

The fixation portion 16 is formed by a diamond-shaped cell 18 that increases the rigidity of the fixation portion 16, and the stent 10 is reliably maintained in its position within a hollow organ.

Both the chamfered region 24 and the end of the stent formed by the fixation are provided with four respective eyelet-shaped markers 28 (three of which are visible in FIG. 1). All four markers 28 in the chamfered area 24 are recognizable in FIG.

The two markers 28 attached to the longest and shortest range points of the stent 10 in the chamfered region 24 are formed symmetrically. Two additional markers 28 are attached to the chamfered region 24, which has an average length of the stent 10. These two markers 28 are formed as asymmetric marks 28a, the region of the asymmetric marker 28a extending towards the shortest range of the stent.

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

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

In FIG. 3, it is observed that the extension connection 20a is provided between the longest diamond cells 18a to produce a more uniform curved opening of all the diamond cells 18 when the stent is expanded.

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

10 Stent 12 Rigid part 14 Flexible part 16 Fixed part 18, 18a, 18b Rhombus cell 20, 20a Connection part 22 Boundary element 24 Chamfered area 26 Open serrated cell 28, 28a Marker 30 End line L Longitudinal α angle

Claims (2)

A method of manufacturing a stent (10).
a) The stent (10) is cut out of a tubular material and
b) The stent (10) is expanded to its expanded state and
c) The shape of the cell (18, 18a, 18b) of the stent (10) is changed and the shape of the cell in the expanded state is fixed .
A core to which fastening means are attached is used to change the shape of the cells of the stents (18, 18a, 18b) and to fix the shape of the cells in the expanded state.
A method characterized in that the fastening means is a needle or mandrel introduced into a hole in the core. d) The method of claim 1, wherein said cell (18, 18a of the stent (10), the changed shape of the cells in the expanded state of 18b), characterized in that it permanently fixed by heating process.

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