stent

Abstract

We provide stents that combine flexibility and expandability. [Solution] The substantially cylindrical stent 10 has closed cell regions 12 containing a plurality of closed cells 16 and open cell regions 14 containing a plurality of open cells 18 arranged alternately along the axial direction, with the area of ​​the open cells 18 being larger than the area of ​​the closed cells 16.

Description

Technical Field

[0001] The present invention relates to a stent.

Background Art

[0002] Stents generally have a closed cell structure and an open cell structure (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A stent with a closed cell structure has high expansion force and is less likely to cause incomplete expansion, but lacks flexibility. On the other hand, a stent with an open cell structure has high flexibility due to the high independence of the cells, but has a lower expansion force compared to the closed cell structure.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a stent having both flexibility and expansion force.

Means for Solving the Problems

[0006] In order to solve the above problems, a stent according to an aspect of the present invention is a substantially cylindrical stent, and along the axial direction of the stent, a closed cell region including a plurality of closed cells and an open cell region including a plurality of open cells are alternately arranged, and the area of the open cells is larger than the area of the closed cells.

Effects of the Invention

[0007] According to the present invention, a stent that combines flexibility and expandability can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic side view of the stent according to the embodiment. [Figure 2] This is an enlarged view of a portion of the stent according to the embodiment. [Figure 3] This figure shows an example of the application of a stent according to the embodiment. [Modes for carrying out the invention]

[0009] Embodiments for carrying out the present invention will be described below. The same or equivalent components are denoted by the same reference numerals, and redundant descriptions will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of explanation. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0010] Figure 1 is a schematic side view of a stent 10 according to an embodiment. In this specification, the direction along the centerline of the stent 10 is referred to as the axial direction, and the radial and circumferential directions with the centerline as the center of the circle are simply referred to as the radial direction and circumferential direction, respectively. In this specification, the terms "axial outer" and "axial inner" and "radial outer" and "radial inner" may also be used. The axial outer side refers to the side of the stent 10 that moves away from the axial center position in the axial direction, and the axial inner side refers to the side that moves closer to the axial center position in the axial direction. The radial outer side refers to the side of the stent 10 that moves away from the centerline in the radial direction, and the radial inner side refers to the side that moves closer to the centerline in the radial direction.

[0011] Stent 10 is placed in a tubular organ within the body to treat conditions such as vascular dissection, aneurysm, and gastrointestinal obstruction. Here, tubular organs refer to, for example, blood vessels, the gastrointestinal tract, etc. Stent 10 is transported to the target location within the tubular organ by a delivery device. At this time, stent 10 is held by the delivery device in a state where the entire stent 10 is contracted radially. In this embodiment, an example of stent 10 being used as an exposed bare stent is described. In addition, stent 10 may be used in combination with other components. For example, stent 10 may be used as a stent graft in combination with a graft, or as a covered stent in combination with a cover.

[0012] The stent 10 according to this embodiment is a self-expanding stent that can expand radially outward by self-expansion. Here, self-expansion refers to expansion due to the restoring force associated with its own elastic deformation. The stent 10 is a laser-cut stent manufactured by laser-cutting a metal pipe such as nickel-titanium.

[0013] As shown in Figure 1, the stent 10 is substantially cylindrical in shape. The peripheral wall of the stent 10 has a mesh pattern structure made up of multiple cells. In this specification, the peripheral wall of the stent 10 refers to the part that separates the inside and outside of the cylindrical structure of the stent 10. A cell refers to the part surrounded by struts that form the mesh pattern of the stent 10. In addition, in the substantially cylindrical structure of the stent 10, the parts of the cell where struts are not present are also considered to be the peripheral wall of the stent 10.

[0014] The stent 10 according to this embodiment comprises a closed-cell region 12 containing a plurality of closed cells 16 and an open-cell region 14 containing a plurality of open cells 18. As shown in Figure 1, the closed-cell region 12 and the open-cell region 14 are arranged alternately along the axial direction.

[0015] As shown in Figure 1, closed cell regions 12 are located at both ends of the stent 10. As described above, the closed cell regions 12 and open cell regions 14 are arranged alternately, so the number of closed cell regions 12 is one more than the number of open cell regions 14. That is, if the number of open cell regions 14 is N, the number of closed cell regions 12 is N+1. Also, in the stent 10, the number of closed cells 16 is greater than the number of open cells 18.

[0016] As shown in Figure 1, the open cell regions 14a at both axial ends are configured as gradually changing sections in which the outer diameter of the stent 10 increases toward the axial ends. In another embodiment, the open cell region 14a at one of the axial ends may be configured as a gradually changing section.

[0017] Figure 2 is an enlarged view of a part of the stent 10. The closed cells 16 and open cells 18 will be described with reference to Figure 2. In the stent 10, the overall approximately cylindrical shape of the stent 10 is formed by struts, and these struts also form the mesh pattern of the closed cells 16 and open cells 18.

[0018] First, let's describe the closed cell 16. In the stent 10 according to this embodiment, the closed cell 16 has a convex polygonal shape. A convex polygon is a polygon in which all interior angles are less than 180 degrees. For example, the closed cell 16 can have a roughly rhombic shape.

[0019] In the closed cell region 12, multiple closed cells 16 are arranged in the circumferential direction. Closely adjacent closed cells 16 in the circumferential direction are connected to each other at their vertices 16a.

[0020] In the stent 10 according to the present embodiment, a plurality of connected closed cells 16 are arranged with the triangular-wave-shaped first strut 21 and the second strut 22 shifted in phase by a half wavelength in the circumferential direction, and it can be considered that the opposing tops of the first strut 21 and the second strut 22 are connected. Here, the wavelengths of the first strut 21 and the second strut 22 are substantially the same. Further, the top of the strut means the extreme point (maximum point or minimum point) of the triangular wave. Also, the amplitude direction of the triangular wave shape is the axial direction, and the wavelength direction of the triangular wave shape is the circumferential direction.

[0021] In the stent 10 according to the present embodiment, in one closed cell region 12, a plurality of closed cells 16 are arranged in a single row in the circumferential direction, but may be arranged in a plurality of rows, such as two rows. In this case, the adjacent closed cells 16 in the axial direction are connected at their vertices.

[0022] Next, the open cell 18 will be described. In the stent 10, the open cell region 14 is arranged between two closed cell regions 12 arranged at a predetermined interval. In the center in the axial direction of one open cell region 14, a triangular-wave-shaped third strut 23 is arranged. The wavelength and amplitude of the third strut 23 may be substantially the same as the wavelengths and amplitudes of the first strut 21 and the second strut 22.

[0023] As shown in FIG. 2, on the right side in the axial direction of the third strut 23, the first strut 21 is arranged at an interval with a phase shift of substantially a half wavelength from the third strut 23. On the left side in the axial direction of the third strut 23, the second strut 22 is arranged at an interval with a phase shift of substantially a half wavelength from the third strut 23.

[0024] The triangular-wave-shaped third strut 23 has a plurality of tops. For example, in FIG. 2, on the right side in the axial direction of the third strut 23, there are tops 24a, 24b, 24c, 24d, 24e, and on the left side in the axial direction of the third strut 23, there are tops 25a, 25b, 25c, 25d, 25e, 25f.

[0025] In the stent 10, only some of the multiple tops of the third strut 23 are connected to the tops of the opposing closed cell 16 struts via links 26. For example, as shown in Figure 2, of the tops 24a, 24b, 24c, 24d, and 24e on the axial right side of the third strut 23, top 24a is connected to the top of the closed cell 16 via link 26, and skipping the two tops 24b and 24c, top 24d is connected to the top of the closed cell 16 via link 26. Similarly, of the tops 25a, 25b, 25c, 25d, 25e, and 25f on the axial left side of the third strut 23, top 25c is connected to the top of the closed cell 16 via link 26, and skipping the two tops 25d and 25e, top 24f is connected to the top of the closed cell 16 via link 26. Thus, in the stent 10, on each axial side of the third strut 23, only one of the three consecutive vertices is connected to the vertex of the opposing closed cell 16. The open cell 18 is a concave polygon enclosed by the third strut 23, the two links 26, and the first strut 21 or the second strut 22. A concave polygon is a polygon in which at least one of the interior angles is greater than 180 degrees. The width of the links 26 may be narrower than the width of one side of the struts 21, 22, and 23. This configuration improves the flexibility of the open cell 18.

[0026] In this embodiment, the stent 10 is configured such that the area of ​​the open cell 18 is larger than the area of ​​the closed cell 16. More preferably, the stent 10 is configured such that the area of ​​the open cell 18 is three times or more the area of ​​the closed cell 16. Here, the cell area refers to the area of ​​the peripheral wall of the stent 10 in one cell (the part surrounded by struts) when the stent 10 is in an expanded state. The cell area can be measured using, for example, a one-shot 3D shape measuring machine VR-6200 manufactured by Keyence Corporation, while rotating the stent 10 in the circumferential direction with a mandrel placed inside. In this case, the result of measuring the surface area of ​​the mandrel in the cell using a mandrel having an outer diameter approximately the same as the inner diameter of the expanded stent 10 can be considered as the cell area.

[0027] Generally, closed-cell structures have high expandability but lack flexibility, while open-cell structures have high flexibility but lower expandability compared to closed-cell structures. In order to curve a stent from a straight state, the outer circumference of the curve needs to stretch and the inner circumference needs to contract. Open-cell structures have a portion at the top that is not connected, which is advantageous for this stretching and contracting during curving, and thus they have high flexibility. In the stent 10 according to this embodiment, closed-cell regions 12 and open-cell regions 14 are arranged alternately throughout the entire axial area of ​​the closed-cell region 12, and further, the area of ​​the open cells 18 is made larger (preferably three times or more) than the area of ​​the closed cells 16, thereby realizing a stent that combines the flexibility of an open-cell structure with the expandability of a closed-cell structure.

[0028] Figure 3 shows an example of the application of the stent 10 according to the embodiment. Figure 3 shows EUS-HGS (Hepaticogastrostomy). EUS-HGS involves anastomosis of the stomach 30 and the intrahepatic bile duct 40 with a stent, and the flexibility of the stent is not required to the same extent as when a stent is placed in a luminal organ. As described above, the expansion force of the closed cell region 12 is high and the expansion force of the open cell region 14 is low, so the closed cell region 12 tends to expand radially and the open cell region 14 tends to contract radially. In other words, since the stent 10 according to this embodiment has alternating closed cell regions 12 and open cell regions 14, it tends to take on a constricted shape in the open cell region 14. Therefore, when the stent 10 is placed at the gastric-intrahepatic bile duct anastomosis, it can be expected to prevent displacement of the stent 10 relative to the anastomosis (an anchor-like effect). Accordingly, the stent 10 according to this embodiment is particularly beneficial in EUS-HGS.

[0029] The embodiments and variations described above are illustrative. The abstract technical ideas derived from them should not be interpreted restrictively to the content of the embodiments and variations. Many design changes, such as changes, additions, and deletions of components, are possible in the embodiments and variations. In the embodiments described above, the content that allows for such design changes is emphasized with the notation "embodiment." However, design changes are also permitted in content without such notation. The hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied. The structures and numerical values ​​mentioned in the embodiments and variations naturally include those that can be considered identical when considering manufacturing tolerances, etc. [Explanation of Symbols]

[0030] 10 stent, 12 closed-cell region, 14 open-cell region, 16 closed cell, 18 open cell, 21 first strut, 22 second strut, 23 third strut, 26 link.

Claims

1. A stent that is roughly cylindrical in shape, Along the axial direction of the stent, closed-cell regions containing multiple closed cells and open-cell regions containing multiple open cells are arranged alternately. A stent characterized in that the area of ​​the open cell is larger than the area of ​​the closed cell.

2. The stent according to claim 1, characterized in that the area of ​​the open cell is three times or more the area of ​​the closed cell.

3. The stent according to claim 1 or 2, characterized in that, in the closed cell region, the plurality of closed cells are arranged in the circumferential direction of the stent.

4. The open cell region includes a triangular wavy strut having a plurality of peaks, The stent according to claim 1 or 2, characterized in that only some of the multiple vertices of the triangular corrugated strut are connected via links to the vertices of the opposing struts constituting the closed cell.

5. The stent according to claim 1 or 2, characterized in that the number of closed cells is greater than the number of open cells.

6. The stent according to claim 1 or 2, characterized in that the number of closed cell regions is greater than the number of open cell regions.

7. The stent according to claim 1 or 2, characterized in that the open cell region at at least one axial end is a gradually changing portion in which the outer diameter of the stent increases toward the axial end.

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