stent

Abstract

To provide a stent that can suppress kinking when placed in a biological lumen. [Solution] The stent 100 has a cylindrical portion 10, which has a plurality of zigzag extensions 20 and a connecting portion 30. The load-applying member 110 is moved from one side to the other to apply a load to the stent 100 that compresses it radially, and the rebound force of the stent 100 at that time is measured. The absolute value of the difference between the first rebound force F1 and the second rebound force F2 is smaller than the absolute value of the difference between the second rebound force F2 and the third rebound force F3.

Description

Technical Field

[0001] The present invention relates to a stent.

Background Art

[0002] As stents used by being placed in a living body lumen, those described in Patent Document 1 are known, for example. The stent of Patent Document 1 has a cylindrical portion, and includes a plurality of annular zigzag extending portions that extend in the circumferential direction while zigzagging in the axial direction of the cylindrical portion, wherein the plurality of zigzag extending portions are arranged to be offset from each other in the axial direction.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] According to studies by the inventors of the present application, the stent of Patent Document 1 has room for improvement from the viewpoint of suppressing kinking when placed in a living body lumen.

Means for Solving the Problem

[0005] According to the present invention, there is provided a stent having a cylindrical portion, the cylindrical portion comprises a plurality of zigzag extending portions that extend in the circumferential direction while zigzagging in the axial direction of the cylindrical portion, wherein the plurality of zigzag extending portions are arranged to be offset from each other in the axial direction, and has connecting portions that connect adjacent ones of the zigzag extending portions in the axial direction, the stent has a coating film bonded to the cylindrical portion, with respect to a measurement result obtained by moving a load applying member from one side to the other side to apply a load that compresses the stent in the radial direction thereof to the stent, and measuring the repulsive force of the stent at that time, With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent, the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the first repulsive force. The second rebound force is defined as the rebound force when the load is applied to the location where the zigzag extension is located in the stent. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from one end of the stent, if the repulsive force when the load is applied to the location where the connection portion is positioned in the stent is defined as the third repulsive force, A stent is provided in which the absolute value of the difference between the first rebound force and the second rebound force is smaller than the absolute value of the difference between the second rebound force and the third rebound force. [Effects of the Invention]

[0006] According to the present invention, it is possible to suppress kinking of the stent when it is placed in a biological lumen. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic plan view of the stent according to the embodiment. [Figure 2] This is a schematic plan view of the stent according to the embodiment, showing the state after the coating film has been removed. [Figure 3] This is a partially enlarged view of the connection part and its surrounding structure in the embodiment, showing the stent in a flat, unfolded state and in an expanded state. [Figure 4] This is a magnified view of part A shown in Figure 3. [Figure 5] This is a partially enlarged view of the connection part and its surrounding structure in the embodiment, showing a cross-section along line AA shown in Figure 1. [Figure 6] Figure 6(a) is a schematic diagram illustrating the first repulsive force, and Figure 6(b) is a schematic diagram illustrating the second repulsive force. [Figure 7]Figure 7(a) is a schematic diagram illustrating the third repulsive force, and Figure 7(b) is a schematic diagram illustrating the fourth repulsive force. [Figure 8] Figure 8(a) is a schematic diagram illustrating the fifth repulsive force, and Figure 8(b) is a schematic diagram illustrating the sixth repulsive force. [Figure 9] Figure 9(a) is a magnified view of section B shown in Figure 6(a), and Figure 9(b) is a magnified view of section C shown in Figure 7(a). [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to Figures 1 to 9(b). In all drawings, similar components are denoted by the same reference numeral, and explanations are omitted where appropriate.

[0009] The stent 100 according to this embodiment has a cylindrical portion 10. The cylindrical portion 10 has a plurality of zigzag extension portions 20 that extend circumferentially while oscillating in a zigzag pattern in the axial direction of the cylindrical portion 10, arranged in a staggered manner in the axial direction, and also has connecting portions 30 that connect adjacent zigzag extension portions 20 in the axial direction. The stent 100 has a coating film (in this embodiment, a first coating film 66 and a second coating film 68) joined to the cylindrical portion 10. The following describes the results of measuring the rebound force of the stent 100 when the load-applying member 110 is moved from one side to the other (from one side to the other in the radial direction of the stent 100) and a load is applied to the stent 100 that compresses it radially. With the rotation angle of the stent 100 adjusted around its axis so that the connection portion 30 is positioned at one end 62a of the stent 100, the repulsive force when a load is applied to the location of the connection portion 30 on the stent 100 is defined as the first repulsive force F1 (see Figure 6(a)). The second rebound force F2 (see Figure 6(b)) is defined as the rebound force when a load is applied to the location where the zigzag extension portion 20 is positioned in the stent 100. With the rotation angle of the stent around its axis adjusted so that the connection portion 30 is positioned to avoid one end 62a of the stent 100, the repulsive force when a load is applied to the location of the connection portion 30 in the stent is defined as the third repulsive force F3 (see Figure 7(a)). The absolute value of the difference between the first rebound force F1 and the second rebound force F2 is smaller than the absolute value of the difference between the second rebound force F2 and the third rebound force F3. In this context, "displaced from each other in the axial direction" means that, in the expanded diameter state of the stent 100, the arrangement area of ​​one zigzag extension 20 and the arrangement area of ​​another zigzag extension 20 adjacent to that zigzag extension 20 may or may not overlap in the axial direction. However, if the arrangement area of ​​one zigzag extension 20 and the arrangement area of ​​another zigzag extension 20 overlap, they are arranged in positions where the zigzag shapes of these zigzag extensions 20 do not intersect each other. Furthermore, in this invention, the direction of movement of the load-applying member 110 (the direction of the load) is linear. Also, "one end 62a" refers to the end of the load-applying member 110 opposite to the direction of the load. Furthermore, "when a load is applied to the location where the connection portion 30 is located in the stent 100" means that the location where the connection portion 30 is located in the axial direction of the stent 100 is locally pressed by the load-applying member 110, and the load-applying member 110 does not contact the zigzag extension portion 20 adjacent to the connection portion 30. Also, as will be described later, if multiple connection portions 30 are located at multiple locations in the axial direction, one of these multiple locations in the axial direction is locally pressed by the load-applying member 110. Further, the expression "when a load is applied to a location where the zigzag extending portion 20 is arranged in the stent 100" means that a location where one zigzag extending portion 20 is arranged in the axial direction of the stent 100 is locally pressed by the load applying member 110, and the load applying member 110 is not in contact with other zigzag extending portions 20 adjacent to the said zigzag extending portion 20. Further, in a case where axially adjacent zigzag extending portions 20 are respectively connected to each other by connecting portions 30 at a plurality of locations in the circumferential direction, the expression "a state in which the rotation angle of the stent 100 around the axis is adjusted such that the connecting portion 30 is arranged at the one-side end 62a" means that any one connecting portion 30 among the plurality of connecting portions 30 is arranged at the one-side end 62a. Further, the expression "a state in which the rotation angle of the stent 100 around the axis is adjusted such that the connecting portion 30 is arranged at a position avoiding the one-side end 62a" means that all of the plurality of connecting portions 30 are arranged at positions avoiding the one-side end 62a. Furthermore, among the plurality of connecting portions 30, a midpoint between any two circumferentially adjacent connecting portions 30 (the midpoint in the circumferential direction) is arranged at the one-side end 62a.

[0010] Note that FIGS. 6(a) and 7(a) are schematic cross-sectional views taken along line A-A shown in FIG. 1, and FIG. 6(b) is a schematic cross-sectional view taken along line B-B shown in FIG. 1. Further, FIG. 8(a) is a schematic cross-sectional view taken along line A-A shown in FIG. 2, and FIG. 7(b) is a schematic cross-sectional view taken along line B-B shown in FIG. 2. In FIGS. 6(a) and 8(a), the stent 100 is in a state where the rotation angle of the stent 100 around the axis is adjusted such that the connecting portion 30 is arranged at the one-side end 62a (the upper end in FIGS. 6(a) and 8(a)). In FIG. 7(a), the stent 100 is in a state where the rotation angle of the stent 100 around the axis is adjusted such that the connecting portion 30 is arranged at a position avoiding the one-side end 62a. Further, in FIG. 2, FIG. 7(b) and FIG. 8(a), the coating film is illustrated by a two-dot chain line.

[0011] The stent 100 is placed in a biological lumen (not shown) using a stent delivery device not shown in the drawings. While the stent 100 is accommodated in an outer sheath (not shown) of the stent delivery device, it is in a reduced-diameter state. When the distal end portion of the outer sheath accommodating the stent 100 is delivered to the placement site in the biological lumen and the stent 100 is released from the outer sheath, the stent 100 elastically recovers from the reduced-diameter state to an expanded-diameter state. In this manner, the stent 100 can be delivered and placed at the placement site in the biological lumen. The reduced-diameter state of the stent 100 refers to a state where the stent 100 is compressed in the radial direction to an extent that allows it to fit within the outer sheath. The expanded-diameter state of the stent 100 refers to a state where the diameter is expanded at least compared to the reduced-diameter state, and is the natural state of the stent 100, for example. In FIGS. 1 to 9(b), the stent 100 is illustrated in the expanded-diameter state (natural state).

[0012] In the following description, the circumferential direction of the tubular portion 10 may be simply referred to as the circumferential direction, the axial direction of the tubular portion 10 may be simply referred to as the axial direction, and the radial direction of the tubular portion 10 may be simply referred to as the radial direction. For convenience, one side in the axial direction (one end side (upper direction in FIG. 1)) is referred to as the distal side, and the other side in the axial direction (the other end side (lower direction in FIG. 1)) is referred to as the proximal side. Unless otherwise specified, the positional relationship and shape of each part of the stent 100 described herein refer to the positional relationship and shape of the stent 100 in the expanded-diameter state.

[0013] In the present invention, the "results of measuring the rebound force of the stent 100" refers to the rebound force (radial force (radial elastic restoring force)) of the stent 100 when a load compressing it radially is applied to the stent 100 in its natural state (expanded state). As an example, the rebound force of the stent 100 is a value measured using a tensile-compression testing machine (AGS-5kNX, manufactured by Shimadzu Corporation, load cell: AGS-X·EZ-X 50N). More specifically, first, the stent 100 is placed on the horizontal plate 120. Next, the end face 110a of the load-applying member 110 (for example, a flat plate member with a thickness of 1 mm) is placed on one end of the stent 100 in the radial direction. At this time, the end face 110a of the load-applying member 110 is positioned parallel to the horizontal plate 120. Furthermore, the width dimensions of the load-applying member 110 and the horizontal plate 120 are larger than the outer diameter of the stent 100, and the entire radial portion of the stent 100 is contained within the respective widths of the load-applying member 110 and the horizontal plate 120. Also, the entire axial portion of the stent 100 is positioned on the horizontal plate 120. Next, the load-applying member 110 is moved radially, and the rebound force is measured while the stent 100 is compressed to 50% of its natural outer diameter. In this manner, the first rebound force F1 to the third rebound force F3 and the fourth rebound force F4 to the sixth rebound force F6, which will be described later, are measured.

[0014] According to this embodiment, as described above, the absolute value of the difference between the first repulsive force F1 and the second repulsive force F2 is smaller than the absolute value of the difference between the second repulsive force F2 and the third repulsive force F3. That is, |F1-F2|<|F2-F3|. With this configuration, discontinuities in rigidity at the boundary between the connecting portion 30 and the zigzag extension portion 20 between adjacent zigzag extension portions 20 in the axial direction can be suppressed, thereby preventing the stent 100 from kinking (buckling) starting from that boundary portion. More specifically, from the viewpoint of suppressing kinking of the stent 100, it is preferable to suppress discontinuities in stiffness between adjacent zigzag extensions 20 in the axial direction. On the other hand, from the viewpoint of ensuring the ease of bending (flexibility) of the stent 100, it is preferable to have an appropriate gradient in stiffness between adjacent zigzag extensions 20 in the axial direction. Therefore, in this embodiment, as will be described later, a plurality of connecting portions 30 are locally arranged between adjacent zigzag extension portions 20 in the axial direction, spaced apart from each other in the circumferential direction. In these plurality of connecting portions 30, the absolute value of the difference between the first repulsive force F1 and the second repulsive force F2 is smaller than the absolute value of the difference between the second repulsive force F2 and the third repulsive force F3, thereby suppressing the discontinuity of rigidity at the boundary between the connecting portion 30 and the zigzag extension portion 20. With this configuration, kinking (buckling) can be suppressed in the stent 100 while ensuring ease of bending (flexibility).

[0015] The cylindrical portion 10, which includes multiple zigzag extensions 20 and connecting portions 30, can be formed, for example, by cutting (for example, laser cutting) a single pipe (for example, a pipe made of a metal or plastic material). The cross-sectional shape of the wire in the cylindrical portion 10 formed by cutting (the cross-sectional shape along the direction perpendicular to the direction of extension of the wire) is approximately rectangular and includes four faces. There are virtually no steps formed at the boundaries between each part of the cylindrical portion 10, and each part is smoothly connected to the others. The material for the cylindrical portion 10 (a single pipe) is not particularly limited, but examples include Ni-Ti alloy and polylactic acid. The outer and inner diameters of the cylindrical portion 10 are substantially constant regardless of their position in the axial direction. However, the present invention is not limited to this example, and the outer diameter and inner diameter of a part of the cylindrical portion 10 may be larger or smaller than the other parts.

[0016] Each of the multiple zigzag extensions 20 is formed in a substantially annular shape, for example, extending in a 360-degree circular manner. The multiple zigzag extensions 20 are formed to have the same diameter as each other and are arranged coaxially with each other. Each of the multiple zigzag extensions 20 has a zigzag shape in which a first extension 22 extending in a direction inclined with respect to the axial direction (for example, the downward-sloping direction to the right in Figure 1) and a second extension 23 inclined in the opposite direction to the inclination direction of the first extension 22 (the upward-sloping direction to the right in Figure 1) are alternately repeated. In each zigzag extension portion 20, the corner (first apex 25) at the boundary between one end of the first extension portion 22 (one end in the extension direction) and one end of the second extension portion 23 adjacent to the first extension portion 22 (same as above) is convex toward the base end, and the corner (second apex 26) at the boundary between the other end of the first extension portion 22 (the other end in the extension direction) and the other end of the second extension portion 23 adjacent to the first extension portion 22 (same as above) is convex toward the tip end. The first vertex 25 and the second vertex 26 are, for example, identical in shape and arranged symmetrically in the axial direction.

[0017] As shown in Figure 1, in this embodiment, the multiple zigzag extensions 20 are arranged such that the first apex 25 of one zigzag extension 20 and the second apex 26 of another zigzag extension 20 adjacent to the said zigzag extension 20 are close to each other in the axial direction.

[0018] In this embodiment, in the multiple zigzag extension sections 20, the length dimension (dimension in the extension direction) of each first extension section 22 and the length dimension (same as above) of each second extension section 23 are set to be, for example, equivalent in length. Furthermore, each first extension portion 22 is set to have the same length dimension as each second extension portion 23. Furthermore, in the multiple zigzag extensions 20, the inclination angle of the first extension 22 with respect to the axis of the cylindrical portion 10 and the inclination angle of the second extension 23 with respect to the axis are set to be the same dimension. Furthermore, the inclination angles of each first extension 22 are set to be the same as those of each other, and the inclination angles of each second extension 23 are also set to be the same as those of each other. The first vertex 25 and the second vertex 26 are formed to be, for example, identical in shape and dimensions to each other. However, in the present invention, for example, in a plurality of zigzag extensions 20, the first extension 22 and the second extension 23 may be set to have equivalent length dimensions (dimensions in the extension direction) and inclination angles, or they may be set to have different length dimensions and inclination angles. Also, each first extension 22 may be set to have equivalent length dimensions and inclination angles, or they may be set to have different length dimensions and inclination angles. Similarly, each second extension 23 may be set to have equivalent length dimensions and inclination angles, or they may be set to have different length dimensions and inclination angles. Furthermore, in the present invention, the first apex 25 and the second apex 26 may be formed in different shapes and dimensions from each other, for example. Furthermore, in the present invention, the number of zigzag extensions 20 on the cylindrical portion 10 is not particularly limited and can be appropriately changed according to the desired dimensions and application of each part of the stent 100.

[0019] Furthermore, in this embodiment, the cylindrical portion 10 has, in addition to the multiple zigzag extensions 20 described above, an end winding portion 40 located at one end in the axial direction (the tip in this embodiment). As shown in Figure 1, the end winding portion 40 includes a plurality of peaks 42 and a plurality of valleys 44, and is formed in a zigzag shape in which the peaks 42 and valleys 44 are arranged alternately in the circumferential direction. Each of the multiple peaks 42 is formed in a convex V-shape toward the tip. Each of the multiple valleys 44 is formed in a convex V-shape toward the base. Furthermore, as shown in Figure 1, the end winding portion 40 includes, for example, a strut portion 46 that connects a peak portion 42 and a valley portion 44 adjacent to the peak portion 42. The end winding portion 40 and the zigzag extension portion 20 adjacent to the end winding portion 40 are connected to each other by a connecting portion 30.

[0020] Here, as described above, adjacent zigzag extensions 20 in the axial direction are connected by connecting parts 30. More specifically, in this embodiment, in the cylindrical portion 10, one zigzag extension portion 20 and another zigzag extension portion 20 adjacent to the said zigzag extension portion 20 are connected to each other by a plurality (for example, three) of connecting portions 30. As shown in Figure 6(a), the multiple connecting parts 30 are arranged radially, avoiding positions that are 180 degrees symmetrical to each other. Furthermore, each connecting part 30 is formed to be the same shape as the others and is arranged rotationally symmetrically with respect to the center of the cylindrical part 10. Each connecting part 30 is arranged at equal angular intervals from each other in the circumferential direction. In this way, each of the multiple zigzag extensions 20 included in the cylindrical portion 10 is connected to one another by connecting portions 30 at multiple locations in the axial direction. In Figures 1 and 2, among the multiple connection parts 30, only the connection part 30 located on one radial side (the front side of the paper in Figures 1 and 2) is selectively shown, and the connection part 30 located on the other radial side (the back side of the paper in Figures 1 and 2) is not shown. Furthermore, in the present invention, the number of connecting portions 30 of the cylindrical portion 10 is not particularly limited, and it is sufficient that adjacent zigzag extension portions 20 are connected to each other by at least one connecting portion 30.

[0021] In this embodiment, the connecting portion 30 connects the first extending portion 22 of one zigzag extending portion 20 (for example, the first extending portion 22a shown in Figure 3) to the first extending portion 22 of another zigzag extending portion 20 that is facing the first extending portion 22 in the axial direction (for example, the first extending portion 22b shown in Figure 3). However, the present invention is not limited to this example. For example, the connecting portion 30 may connect a second extension portion 23 of one zigzag extension portion 20 to a second extension portion 23 of another zigzag extension portion 20 that is axially opposite to the second extension portion 23 of the first extension portion 23 of the first zigzag extension portion 20 to each other, or it may connect a first extension portion 22 of one zigzag extension portion 20 to a second extension portion 23 of another zigzag extension portion 20 that is adjacent to the first extension portion 22 of the first extension portion 22 of the first extension portion 22 of the first extension portion 22 of the first zigzag extension portion 20 to each other.

[0022] In this embodiment, the intermediate portion 33 of the connecting portion 30 (the portion between one end 31 and the other end 32) extends linearly along the axial direction. On the other hand, one end 31 of the connecting portion 30 (one end in the extending direction of the connecting portion 30) extends in a direction that includes a component in one direction in the circumferential direction. Furthermore, the one end 31 extends in a direction that includes a component in a direction perpendicular to the first extending portion 22a to which the one end 31 is connected. Similarly, the other end 32 of the connecting portion 30 (the other end in the extending direction of the connecting portion 30) extends in a direction that includes a component in the other direction in the circumferential direction. Furthermore, the other end 32 extends in a direction that includes a component in a direction perpendicular to the first extending portion 22b to which the other end 32 is connected. Furthermore, as shown in Figures 3 and 4, at one end 31, the end connected to the first extension 22a gradually increases in width toward the first extension 22. This ensures good structural strength at the boundary between the one end 31 and the first extension 22. Similarly, at the other end 32, the end connected to the first extension 22b gradually increases in width toward the first extension 22. This ensures good structural strength at the boundary between the other end 32 and the first extension 22. Furthermore, the length dimension of the intermediate portion 33 is greater than the respective lengths of one end 31 and the other end 32, for example, 10 to 50 times the respective lengths of one end 31 and the other end 32, preferably 15 to 40 times.

[0023] As shown in Figure 1, the stent 100 has a first portion 61 in which the cylindrical portion 10 is covered with a single layer coating film, and a second portion 63 in which the cylindrical portion 10 is covered with multiple layers coating films. More specifically, the stent 100 has a first coating film 66, which is a cylindrical film in the same layer as the cylindrical portion 10, and a second coating film 68 which is externally mounted on the cylindrical portion 10. The first portion 61 has a single-layer structure of the first coating film 66, and the second portion 63 has a two-layer structure of the first coating film 66 and the second coating film 68. In Figure 1, the formation region of the second portion 63 is represented by a shading of multiple dots arranged at equal intervals. The first coating film 66 is made of a resin material such as silicone rubber. The first coating film 66 is formed, for example, by impregnating the cylindrical portion 10 with the resin material. The second coating film 68 is, for example, made of a resin material and is an adhesive strip-shaped member that is wound around the outer surface of the first coating film 66. However, the present invention is not limited to this example, and the second coating film 68 may be formed, for example, by applying a liquid elastomer and then drying it to adhere it to the first coating film 66. In this invention, the coating film covering the cylindrical portion 10 includes a film covering the outer circumference of the cylindrical portion 10, a film covering the inner circumference of the cylindrical portion 10, and a film of the same layer as the cylindrical portion 10.

[0024] Furthermore, one end of the stent in the axial direction is a protruding membrane portion 65 in which the coating film (first coating film 66 in this embodiment) protrudes axially from the cylindrical portion 10, and the protruding membrane portion 65, the first portion 61, and the second portion 63 are arranged in this order in the axial direction. With this configuration, in the stent 100, the first portion 61, which is covered with a single layer of coating film, is interposed between the second portion 63, which has the highest rigidity, and the protruding membrane portion 65, which has the weakest point. This suppresses abrupt changes in rigidity in the axial direction of the stent 00 and prevents the occurrence of kinks.

[0025] More specifically, as shown in Figure 1, in this embodiment, the protruding film portion 65, the first portion 61a, the second portion 63, and the second first portion 61b are arranged in this order in the axial direction. With this configuration, the rigidity of the stent 100 can be locally ensured by the second part 63. More specifically, in this embodiment, the protruding membrane portion 65 constitutes a check valve portion, and the protruding membrane portion 65 (check valve portion) allows flow to one side (for example, the base end side) in the axial direction of the cylindrical portion 10, while restricting flow to the opposite side (for example, the tip side). Furthermore, the second portion 63 adjacent to the protruding membrane portion 65 (check valve portion) is an anti-reversal portion that prevents the protruding membrane portion 65 from reversing.

[0026] In this embodiment, as described above, the dimensions and shape of each part of the cylindrical portion 10 (connecting portion 30 and zigzag extension portion 20) and the rigidity of the coating film (first coating film 66) are set such that the absolute value of the difference between the first repulsive force F1 and the second repulsive force F2 is smaller than the absolute value of the difference between the second repulsive force F2 and the third repulsive force F3. This suppresses discontinuities in rigidity at the boundary between the connecting portion 30 and the zigzag extension portion 20, thereby preventing the stent 100 from kinking (buckling).

[0027] More specifically, in the stent 100, factors that contribute to increasing the first repulsive force F1 include, for example, the rigidity of the zigzag extension portion 20 and the ratio of the thickness dimension to the width dimension in the connection portion 30. As described above, in the first rebound force F1, the rotation angle of the stent 100 around its axis is adjusted so that the connection part 30 is positioned at one end 62a of the stent 100, and a load is applied to the location on the stent 100 where the connection part 30 is positioned. As a result, as soon as the load-applying member 110 starts to move, the connection part 30 and, by extension, the zigzag extension part 20 connected by the connection part 30 deform due to the load from the load-applying member 110, generating a rebound force. That is, in the first rebound force F1, compared to the third rebound force F3, a sufficient rebound force is obtained not only from the deformation of the connection part 30 but also from the deformation of the zigzag extension part 20. Therefore, by appropriately setting the dimensions of each part of the zigzag extension part 20 (first extension part 22 and second extension part 23) and adjusting the rigidity of the zigzag extension part 20, the first rebound force F1 can be set to a desired size. Furthermore, in this embodiment, the thickness dimension of the connecting portion 30 (T1 shown in Figure 5) is greater than the width dimension of the connecting portion 30 (the dimension in the direction perpendicular to the extending direction of the connecting portion 30 (W1 shown in Figure 5)). Therefore, the cross-sectional shape of the intermediate portion 33 of the connecting portion 30 along the direction perpendicular to the axial direction (the direction perpendicular to the extending direction of the intermediate portion 33) (see Figure 5) is a roughly rectangular shape that is elongated in the radial direction. In this configuration, as shown in Figures 6(a) and 9(a), when the rotation angle of the stent 100 around its axis is adjusted so that the connection portion 30 is positioned at one end 62a of the stent 100, and a load is applied to the location of the connection portion 30 on the stent 100, the pressing direction of the load-applying member 110 (direction of arrow C shown in Figure 9(a)) is along the longitudinal direction of the rectangular cross-section of the connection portion 30 (thickness direction of the connection portion 30). Here, in a rectangular cross-section, the second moment of area has a positive correlation with the cube of the height (in this embodiment, the thickness dimension of the connection portion 30). That is, increasing the thickness dimension of the connection portion 30 increases the first repulsive force F1. For this reason, the first repulsive force F1 can be set to a desired size by appropriately setting the ratio of the thickness dimension T1 and the width dimension W1 of the connection portion 30. Furthermore, since the width dimension W1 of the connection portion 30 is smaller than the thickness dimension T1, the ease of bending (flexibility) of the connection portion 30 can be ensured. Therefore, in the stent 100, sufficient ease of bending (flexibility) can be achieved while suppressing kinking (buckling). As shown in Figure 9(b), in the third rebound force F3, when the rotation angle of the stent around its axis is adjusted so that the connection portion 30 is positioned to avoid one end 62a of the stent 100, and a load is applied to the location where the connection portion 30 is positioned in the stent, the pressing direction of the load-applying member 110 (direction of arrow C shown in Figure 9(b)) is perpendicular to the longitudinal direction of the cross-sectional shape of the connection portion 30 (thickness direction of the connection portion 30) (for example, a direction perpendicular to one of the two diagonals 401 of the rectangular cross-section). Therefore, compared to the first rebound force F1, the influence of the thickness dimension T1 of the connection portion 30 on the third rebound force F3 is small.

[0028] In contrast, factors that contribute to an increase in the third repulsive force F3 include, for example, the rigidity of the coating film (first coating film 66), and the number, arrangement, and shape of the connection parts 30. As described above, in the third rebound force F3, the rotation angle of the stent around its axis is adjusted so that the connection portion 30 is positioned away from one end 62a of the stent 100, and a load is applied to the location of the connection portion 30 on the stent. At this time, the load-applying member 110 mainly presses the first coating film 66 until it reaches the position of the connection portion 30, so in the third rebound force F3, a greater rebound force due to the elastic deformation of the first coating film 66 is obtained compared to the first rebound force F1. For this reason, in the third rebound force F3, the desired size of the third rebound force F3 can be achieved by adjusting the material and film thickness of the coating film (first coating film 66). Furthermore, if multiple (for example, three) connection points 30 are arranged at equal angular intervals in the circumferential direction, and the rotation angle of the stent 100 around the axis is adjusted so that the connection points 30 are positioned to avoid one end 62a, then the midpoint (circumferential midpoint) between any two of the multiple connection points 30 (for example, connection points 30a and 30b shown in Figure 7(a)) will be positioned at one end 62a. As a result, when the load-applying member 110 presses against the first coating film 66, the first coating film 66 is held under tension between these two connection points 30a and 30b. Therefore, the repulsive force of the first coating film 66, and thus the third repulsive force F3, can be increased. Furthermore, if multiple connection parts 30 are arranged at equal angular intervals in the circumferential direction, and the rotation angle of the stent 100 around the axis is adjusted so that the connection parts 30 are positioned to avoid one end 62a, the load-applying member 110 will press against multiple connection parts 30 (for example, connection parts 30a and 30b shown in Figure 7(a)) at once. As a result, the repulsive force of each of the multiple connection parts 30 (two connection parts 30a and 30b) is obtained, and the third repulsive force F3 can be increased. Furthermore, as described above, in this embodiment, one end 31 of the connecting portion 30 extends in a direction that includes a component in one direction in the circumferential direction, and also extends in a direction that includes a component in a direction perpendicular to the first extending portion 22 to which the one end 31 is connected. At the one end 31, the width dimension of the end on the side connected to the first extending portion 22 gradually increases toward the first extending portion 22. Similarly, the other end 32 of the connecting portion 30 extends in a direction that includes a component in the other direction in the circumferential direction, and also extends in a direction that includes a component in a direction perpendicular to the first extending portion 22 to which the one end 32 is connected. At the other end 32, the width dimension of the end on the side connected to the first extending portion 22 gradually increases toward the first extending portion 22. With this configuration, when the multiple connection parts 30 (two connection parts 30a) are pressed by the load-applying member 110, it is possible to suppress the rotation of the intermediate part 33 of the connection parts 30 around its axis. Therefore, when the load-applying member 110 presses the first coating film 66, the first coating film 66 maintains a good state of tension between these two connection parts 30a and 30b, and the repulsive force of each of the multiple connection parts 30 (connection parts 30a and 30b) is sufficiently secured, thereby increasing the third repulsive force F3.

[0029] Thus, in this embodiment, by appropriately setting the dimensions and shape of each part of the cylindrical portion 10 (connecting portion 30 and zigzag extension portion 20) and the rigidity of the coating film (first coating film 66), it is possible to realize a configuration in which the absolute value of the difference between the first repulsive force F1 and the second repulsive force F2 is smaller than the absolute value of the difference between the second repulsive force F2 and the third repulsive force F3.

[0030] As an example, the thickness dimension T1 of the connecting portion 30 is preferably 1.1 times or more and 2.5 times or less the width dimension W1 of the connecting portion 30, and more preferably 1.2 times or more and 2.0 times or less the width dimension W1. By having a thickness T1 of the connecting portion 30 that is 1.2 times or more the width W1, a moderate first repulsive force F1 can be secured, enabling good diameter expansion of the stent 100. Furthermore, the ease of bending (flexibility) of the connecting portion 30 and, consequently, the stent 100 can be ensured. On the other hand, by having a thickness T1 of the connecting portion 30 that is 2.0 times or less the width W1, an excessive increase in the first repulsive force F1 can be suppressed, and a configuration can be achieved in which the absolute value of the difference between the first repulsive force F1 and the second repulsive force F2 is smaller than the absolute value of the difference between the second repulsive force F2 and the third repulsive force F3. Furthermore, in this embodiment, as described above, the first coating film 66 is a cylindrical film in the same layer as the cylindrical portion 10 and is made of a resin material such as silicone rubber. More specifically, as shown in Figure 5, the first coating film 66 includes an outer portion 66a that covers the outer circumferential surface of the cylindrical portion 10 and an inner portion 66b that covers the inner circumferential surface of the cylindrical portion 10. With this configuration, the rigidity of the first coating film 66 is adequately ensured, and the state in which the first coating film 66 and the cylindrical portion 10 are in close contact can be maintained well. Therefore, when the load-applying member 110 presses against the first coating film 66, sufficient tension is applied to the first coating film 66 between these two connecting portions 30a and 30b. Thus, the third repulsive force F3 can be well ensured.

[0031] Furthermore, in this embodiment, the third repulsive force F3 is greater than the first repulsive force F1 and the second repulsive force F2. With this configuration, in addition to suppressing discontinuities in rigidity at the boundary between the connection portion 30 and the zigzag extension portion 20, appropriate rigidity can be obtained in the region between adjacent connection portions 30 in the circumferential direction of the stent 100. Therefore, unintended deformation and kinking can be more reliably suppressed around the entire circumference of the outer shape of the stent 100. Furthermore, appropriate expandability can be ensured in both the area where the connection portions 30 are located and the region between adjacent connection portions 30 in the circumferential direction of the stent 100, so that the lumen of the enlarged stent 100 can be well maintained.

[0032] Furthermore, in this embodiment, if the repulsive force when a load is applied to the location where the zigzag extension portion 20 is located in the stent 100 from which the coating film has been removed is defined as the fourth repulsive force F4 (see Figure 7(b)), then the second repulsive force F2 is greater than the fourth repulsive force F4. With this configuration, the coating film can be used to create a structure in which the repulsive force in the area where the zigzag extension portion 20 is located in the stent 100 is enhanced (strengthened).

[0033] Furthermore, in this embodiment, if the rotation angle of the stent around its axis is adjusted so that the connection portion 30 is positioned at one end of the stent from which the coating film has been removed, and a load is applied to the location of the connection portion 30 in the stent, the repulsive force when this load is applied is the fifth repulsive force F5 (see Figure 8(a)), then the first repulsive force F1 is greater than the fifth repulsive force F5. With this configuration, the coating film enhances (strengthens) the repulsive force in the area where the connection portion 30 is located in the stent 100, thereby realizing a structure in which this force is increased.

[0034] Furthermore, in this embodiment, the fifth repulsive force F5 is greater than the fourth repulsive force F4. With this configuration, even if the coating peels off from the cylindrical portion 10, the repulsive force can be secured at the locally arranged connecting portion 30 in the circumferential direction, thereby suppressing the occurrence of kinks in the stent 100. More specifically, as described above, in this embodiment, the intermediate portion 33 of the connecting portion 30 extends linearly along the axial direction. On the other hand, the first extending portion 22 and the second extending portion 23 of the zigzag extending portion 20 extend in a direction intersecting the axial direction. Therefore, the fifth repulsive force F5 can be configured to be greater than the fourth repulsive force F4.

[0035] Furthermore, in this embodiment, the repulsive force when a load is applied to the location where the zigzag extension 20 is located in the first part 61 is the second repulsive force F2, and the repulsive force when a load is applied to the location where the zigzag extension 20 is located in the second part 63 is the sixth repulsive force (see Figure 8(b)). The sixth repulsive force F6 is greater than the second repulsive force F2. Furthermore, the "locations in the first part 61 where the zigzag extension 20 is located" refer to the zigzag extension 20 that is entirely located in the first part 61, out of a group of zigzag extensions 20. In other words, the zigzag extension 20 that spans both the first part 61 and the second part 63 is not included in the above-mentioned "zigzag extension 20". Similarly, the "location where the zigzag extension 20 is located in the second part 63" refers to the zigzag extension 20 that is entirely located in the second part 63 among a plurality of zigzag extensions 20. In other words, the zigzag extension 20 that spans both the first part 61 and the second part 63 is not included in the above-mentioned "zigzag extension 20". According to the above configuration, in the zigzag extension portion 20, the repulsive force is greater in the two-layer portion of the coating film compared to the single-layer portion. Therefore, by appropriately setting the arrangement and formation area of ​​the two-layer portion, a stent 100 with a desired stiffness gradient can be realized.

[0036] In this embodiment, the third repulsive force F3 is preferably, for example, 1.05 times or more and 2 times or less the first repulsive force F1, and more preferably 1.1 times or more and 2 times or less the first repulsive force F1. The second rebound force F2 is preferably, for example, 1.05 times or more and 2 times or less the fourth rebound force F4, and more preferably 1.1 times or more and 2 times or less the fourth rebound force F4. The first rebound force F1 is preferably, for example, 1.05 times or more and 2 times or less the fifth rebound force F5, and more preferably 1.1 times or more and 2 times or less the fifth rebound force F5. The sixth rebound force F6 is preferably, for example, 1.05 times or more and 2 times or less the second rebound force F2, and more preferably 1.1 times or more and 2 times or less the second rebound force F2. In this embodiment, by appropriately setting the dimensions and shape of each part of the cylindrical portion 10 (connecting portion 30 and zigzag extension portion 20) and the rigidity of the coating film (first coating film 66 and second coating film 68), a desired relationship between the magnitudes of the first repulsive force F1 to the sixth repulsive force F6 can be achieved. However, in the present invention, the relative magnitudes of the first repulsion force F1 to the sixth repulsion force F6 are not limited to the above example, and can be appropriately set according to the application of the stent 100 and the desired expansion force of the stent 100.

[0037] Although embodiments have been described above with reference to the drawings, these are merely examples of the present invention, and the present invention is not limited to the above embodiments. It also includes various modifications, improvements, and other forms as long as the objectives of the present invention are achieved.

[0038] Furthermore, the various components of the stent 100 do not need to be independent entities; it is permissible for multiple components to be formed as a single member, for one component to be made up of multiple members, for one component to be part of another component, and for parts of one component to overlap with parts of another component.

[0039] This embodiment encompasses the following technical concepts. (1) A stent having a cylindrical portion, The aforementioned cylindrical portion is The cylindrical portion has multiple zigzag extending portions that extend circumferentially while oscillating in a zigzag pattern in the axial direction, and these portions are arranged to be offset from each other in the axial direction, It has connecting parts that connect adjacent zigzag extensions in the axial direction, The stent has a coating film joined to the cylindrical portion, The load-applying member was moved from one side to the other, and a load was applied to the stent that compresses it radially. The rebound force of the stent at that time was then measured, and the results were as follows: With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent, the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the first repulsive force. The second rebound force is defined as the rebound force when the load is applied to the location where the zigzag extension is located in the stent. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from one end of the stent, if the repulsive force when the load is applied to the location where the connection portion is positioned in the stent is defined as the third repulsive force, A stent in which the absolute value of the difference between the first rebound force and the second rebound force is smaller than the absolute value of the difference between the second rebound force and the third rebound force. (2) The stent according to (1) wherein the third repulsive force is greater than the first and second repulsive forces. (3) If the fourth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed, A stent according to (1) or (2) in which the second repulsive force is greater than the fourth repulsive force. (4) With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent from which the coating film has been removed, if the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the fifth repulsive force, A stent according to any one of (1) to (3) above, wherein the first rebound force is greater than the fifth rebound force. (5) If the fourth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed, The stent described in (4) wherein the fifth repulsive force is greater than the fourth repulsive force. (6) The stent has a first portion in which the cylindrical portion is covered with a single layer of the coating film, and a second portion in which the cylindrical portion is covered with multiple layers of the coating film, The second repulsive force is the repulsive force when the load is applied to the location in the first part where the zigzag extension is located. If the sixth rebound force is defined as the rebound force when the load is applied to the location where the zigzag extension is located in the second part, A stent according to any one of (1) to (5) above, wherein the sixth repulsive force is greater than the second repulsive force. (7) One end of the stent in the axial direction is a protruding membrane portion in which the coating membrane protrudes axially from the cylindrical portion, The stent according to (6), wherein the protruding membrane portion, the first portion, and the second portion are arranged in this order in the axial direction. (8) The stent according to (7), wherein the protruding membrane portion, the first portion, the second portion, and the second first portion are arranged in this order in the axial direction. [Explanation of Symbols]

[0040] 10. Cylindrical part 20 Multiple zigzag extensions 22, 22a, 22b 1st extension part 23 Second extension part 25 1st top 26 2nd top 30, 30a, 30b connection section 31 One end 32 Other end 33 Middle section 40 End winding section 42 Yamabe 44 Tanibe 46 Strut section 61, 61a, 61b Part 1 63 Part 2 65 Protruding membrane part 66 First coating film 66a outer part 66b Inner part 68 Second coating film 100 stents 110 Load-applying member 110a end face 120 horizontal board F1 First rebound force F2 Second rebound force F3 Third rebound force F4 4th rebound force F5 Fifth rebound force F6 6th rebound force

Claims

1. A stent having a tubular portion, The aforementioned cylindrical portion is The cylindrical portion has multiple zigzag extending portions that extend circumferentially while oscillating in a zigzag pattern in the axial direction, and these portions are arranged to be offset from each other in the axial direction, It has connecting parts that connect adjacent zigzag extensions in the axial direction, The stent has a coating film joined to the cylindrical portion, The load-applying member was moved from one side to the other, and a load was applied to the stent that compresses it radially. The rebound force of the stent at that time was then measured, and the results were as follows: With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent, the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the first repulsive force. The second rebound force is defined as the rebound force when the load is applied to the location where the zigzag extension is positioned in the stent. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from one end of the stent, if the repulsive force when the load is applied to the location where the connection portion is positioned in the stent is defined as the third repulsive force, A stent in which the absolute value of the difference between the first repulsive force and the second repulsive force is smaller than the absolute value of the difference between the second repulsive force and the third repulsive force.

2. The stent according to claim 1, wherein the third repulsive force is greater than the first and second repulsive forces.

3. If the fourth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed, The stent according to claim 1 or 2, wherein the second repulsive force is greater than the fourth repulsive force.

4. With the rotation angle of the stent adjusted around its axis so that the connecting portion is positioned at one end of the stent from which the coating film has been removed, if the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the fifth repulsive force, The stent according to claim 1 or 2, wherein the first repulsive force is greater than the fifth repulsive force.

5. If the fourth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed, The stent according to claim 4, wherein the fifth repulsive force is greater than the fourth repulsive force.

6. The stent has a first portion in which the cylindrical portion is covered with a single layer of the coating film, and a second portion in which the cylindrical portion is covered with multiple layers of the coating film. The second repulsive force is the repulsive force when the load is applied to the location in the first part where the zigzag extension is located. If the sixth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the second part, The stent according to claim 1 or 2, wherein the sixth repulsive force is greater than the second repulsive force.

7. One end of the stent in the axial direction is a protruding membrane portion in which the coating membrane protrudes axially from the cylindrical portion. The stent according to claim 6, wherein the protruding membrane portion, the first portion, and the second portion are arranged in this order in the axial direction.

8. The stent according to claim 7, wherein the protruding membrane portion, the first portion, the second portion, and the second first portion are arranged in this order in the axial direction.

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