Stents

Abstract

A stent that can be more easily placed in a living lumen is provided. [Solution] The stent 100 is a stent having a tubular portion 10, which has a plurality of annular zigzag extension portions 20 that extend circumferentially while zigzag in the axial direction of the tubular portion 10, with the plurality of annular zigzag extension portions 20 arranged offset from each other in the axial direction, and which have connecting portions 30 that connect adjacent zigzag extension portions 20 in the axial direction, and in the circumferential direction of the tubular portion 10, the radius of curvature of the connecting portions 30 is smaller than the radius of curvature of the annular zigzag extension portions 20.

Description

[Technical field]

[0001] The present invention relates to a stent. [Background technology]

[0002] An example of a stent that is placed in a biological lumen is described in Patent Document 1. The stent in Patent Document 1 has a tubular portion and a plurality of annular zigzag extending portions that extend in the circumferential direction while oscillating in a zigzag pattern in the axial direction of the tubular portion, and are arranged offset from one another in the axial direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 195841 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the investigations of the present inventors, there is still room for improvement in the stent of Patent Document 1 with regard to the ease of placement within a biological lumen. [Means for solving the problem]

[0005] According to the present invention, there is provided a stent having a tubular portion, The cylindrical portion is The cylindrical portion has a plurality of annular zigzag extending portions extending in a circumferential direction while swaying in a zigzag manner in an axial direction thereof, the zigzag extending portions being arranged offset from each other in the axial direction thereof, a connecting portion connecting adjacent ones of the zigzag extending portions in the axial direction, In the circumferential direction of the cylindrical portion, the radius of curvature of the connecting portion is smaller than the radius of curvature of the annular zigzag extending portion. Ku, The connection portion is disposed inside an imaginary cylindrical shape that envelops the assembly of the plurality of zigzag extension portions with a minimum diameter. A stent is provided. Effect of the Invention

[0006] According to the present invention, a stent can be more easily placed in a biological lumen. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic plan view of a stent according to an embodiment. [Diagram 2] FIG. 2 is a partially enlarged perspective view of a connection portion and its surrounding structure in the embodiment. [Diagram 3] FIG. 2 is a partially enlarged view of a connection portion and its surrounding structure in an embodiment, showing the stent in a flat deployed state. [Figure 4] 4(a) is a cross-sectional view taken along line AA shown in FIG. 3, FIG. 4(b) is a cross-sectional view taken along line BB shown in FIG. 3, and FIG. 4(c) is a cross-sectional view taken along line CC shown in FIG. 3. [Diagram 5] FIG. 5(a) is a schematic diagram of a connection portion in the embodiment, and FIG. 5(b) is a partially enlarged view of FIG. 5(a). [Figure 6] FIG. 4 is a partial enlarged view of part A shown in FIG. [Figure 7] FIG. 2 is a cross-sectional view of the stent according to the embodiment, showing the state in which it is placed in a biological lumen. [Figure 8] FIG. 13 is a partially enlarged view of a connection portion and its surrounding structure in Modification 1, showing a state in which the stent is deployed flat and has an expanded diameter. [Figure 9] 9(a) is a cross-sectional view taken along line AA shown in FIG. 8, FIG. 9(b) is a cross-sectional view taken along line BB shown in FIG. 8, and FIG. 9(c) is a cross-sectional view taken along line CC shown in FIG. 8. [Figure 10] FIG. 11 is a partially enlarged view of a connection portion and its surrounding structure in Modification 2, showing a state in which the stent is deployed flat and has an expanded diameter. [Figure 11] 11(a) is a cross-sectional view taken along line AA shown in FIG. 10, FIG. 11(b) is a cross-sectional view taken along line BB shown in FIG. 10, and FIG. 11(c) is a cross-sectional view taken along line CC shown in FIG. 10. [Figure 12] FIG. 11 is a partially enlarged view of a connection portion and its surrounding structure in Modification 3, showing a state in which the stent is deployed flat and has an expanded diameter. [Figure 13] 13(a) is a cross-sectional view taken along line AA shown in FIG. 12, FIG. 13(b) is a cross-sectional view taken along line BB shown in FIG. 12, and FIG. 13(c) is a cross-sectional view taken along line CC shown in FIG. 12. [Figure 14] FIG. 13 is a partially enlarged view of a connection portion and its surrounding structure in Modification 4, showing a state in which the stent is deployed flat and has an expanded diameter. [Figure 15] FIG. 13 is a partially enlarged view of a connection portion and its surrounding structure in Modification 5, showing a state in which the stent is deployed flat and has an expanded diameter. [Figure 16] 16(a) is a cross-sectional view taken along line AA shown in FIG. 15, FIG. 16(b) is a cross-sectional view taken along line BB shown in FIG. 15, and FIG. 16(c) is a cross-sectional view taken along line CC shown in FIG. 15. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In addition, in all drawings, similar components are given the same symbols and descriptions are omitted as appropriate. The axial direction of the stent 100 is the up-down direction in Fig. 1. Fig. 3 is a diagram showing the stent 100 cut along its axial direction at one point in the circumferential direction and flattened out, and the left-right direction in Fig. 3 corresponds to the circumferential direction of the stent 100. Fig. 1 also shows a simplified shape of the multiple zigzag extension portions 20. Fig. 7 shows the stent 100 in a cross section cut along a direction perpendicular to the axis of the tubular portion 10.

[0009] The stent 100 according to this embodiment is a stent having a tubular portion 10. The tubular portion 10 has a plurality of annular zigzag extension portions 20 that extend circumferentially while oscillating in a zigzag manner in the axial direction of the tubular portion 10, and are arranged offset from each other in the axial direction, and has a connecting portion 30 that connects adjacent zigzag extension portions 20 in the axial direction. As shown in FIG. 4( b ), in the circumferential direction of the tubular portion 10 , the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extending portion 20 . Here, the "radius of curvature of the connection part 30" will be described in more detail. First, when the cylindrical part 10 is viewed in the axial direction, a plurality of points (for example, 10 points) plotted at equal intervals from one end 30a to the other end 30b of the outer circumferential surface of the connection part 30 in the circumferential direction are designated as P1, P2, P3, P4, P5, P6, P7, P8, P9, and P10 (see Fig. 5(a) and Fig. 5(b)). Note that, for convenience, Fig. 5(a) and Fig. 5(b) show a schematic and simplified shape of the connection part 30 viewed in the axial direction. Next, a point equidistant from P1 to P3 is designated as C1 (see FIG. 5(b)), and the radial distance between P1 to P3 and C1 is designated as R1. Similarly, a point equidistant from P2 to P4 is designated as C2, and the radial distance between P2 to P4 and C2 is designated as R2. A point equidistant from P3 to P5 is designated as C3, and the radial distance between P3 to P5 and C3 is designated as R3. A point equidistant from P4 to P6 is designated as C4, and the radial distance between P4 to P6 and C4 is designated as R4. A point equidistant from P5 to P7 is designated as C5, and the radial distance between P5 to P7 and C5 is designated as R5. A point equidistant from P6 to P8 is designated as C6, and the radial distance between P6 to P8 and C6 is designated as R6. A point equidistant from P7-P9 is C7, and the radial distance between P7-P9 and C7 is R7. A point equidistant from P8-P10 is C8, and the radial distance between P8-P10 and C8 is R8. The average value of the distances R1-R8 thus determined is the "radius of curvature of connection portion 30." Similarly, the "radius of curvature of the zigzag extension portion 20" is the average value of the radial distances R1 to R8 between multiple points P1 to P10 plotted at equal intervals from one end to the other end of the outer circumferential surface of the zigzag extension portion 20 when viewed in the axial direction of the tubular portion 10 and the corresponding points C1 to C8. In the present invention, "the radius of curvature of the connection portion 30 is smaller than the radius of curvature of the annular zigzag extension portion 20 in the circumferential direction of the tubular portion 10" means that the radius of curvature of the zigzag extension portion 20 calculated as described above is at least 1.1 times the radius of curvature of the connection portion 30, preferably 1.2 times the radius of curvature of the connection portion 30, more preferably 1.5 times the radius of curvature of the connection portion 30, and even more preferably 3 times the radius of curvature of the connection portion 30. Therefore, as long as this condition is satisfied, the radius of curvature of a part of the connection portion 30 may be equal to the radius of curvature of the zigzag extension portion 20 in the circumferential direction of the tubular portion 10, or may be larger than the radius of curvature of the zigzag extension portion 20. In addition, the term "displaced from each other in the axial direction" used here means that, in the radially expanded state of the stent 100, the arrangement region 401 (see FIG. 1) of one zigzag extension portion 20 and the arrangement region 402 (see FIG. 1) of another zigzag extension portion 20 adjacent to the zigzag extension portion 20 may or may not overlap each other in the axial direction. However, when the arrangement region 401 of one zigzag extension portion 20 and the arrangement region 402 of another zigzag extension portion 20 overlap each other, the zigzag shapes of these zigzag extension portions 20 are arranged at positions that do not intersect with each other.

[0010] The stent 100 is placed in a body lumen using a stent placement device (not shown). The stent 100 is in a reduced-diameter state while housed in an outer sheath (not shown) of a stent placement device. When the distal end of the outer sheath housing the stent 100 is delivered to an indwelling site in a biological lumen 300 (see FIG. 7) and the stent 100 is released from the outer sheath, the stent 100 elastically restores from the reduced-diameter state to an expanded-diameter state. In this way, the stent 100 can be transported and placed at the indwelling site in the biological lumen 300. The reduced diameter state of the stent 100 means a state in which the stent 100 is compressed in the radial direction to such an extent that the stent 100 can be present within the outer sheath. The expanded diameter state of the stent 100 means a state in which the stent 100 is at least expanded in diameter compared to the reduced diameter state, for example, the natural state of the stent 100. In Figs. 1 to 7, the stent 100 is illustrated in the expanded diameter state (natural state).

[0011] In this embodiment, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extending portion 20 in the circumferential direction of the tubular portion 10 . This configuration can prevent both circumferential ends of the connection part 30 from getting caught on the inner wall surface of the biological lumen 300. Furthermore, when the connection part 30 expands and contracts as the diameter of the stent 100 expands, the connection part 30 is less likely to come into contact with the inner wall surface of the biological lumen 300, so that the expansion and contraction properties and flexibility of the stent 100 can be ensured. Therefore, the stent 100 can be more easily placed in the biological lumen 300 .

[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)) will be referred to as the tip side, and the other side in the axial direction (other end side (lower direction in FIG. 1)) will be referred to as the base end side. Moreover, unless otherwise specified, the positional relationship and shape of each part of the stent 100 are described based on the positional relationship and shape of the stent 100 in its expanded radial state.

[0013] The cylindrical portion 10 including the multiple zigzag extending portions 20 and the connecting portion 30 can be formed, for example, by cutting (for example, laser processing (laser cutting)) a ​​single pipe (for example, a pipe made of a metal material or a plastic material). When forming the cylindrical portion 10, the multiple zigzag extending portions 20 and the connecting portion 30 are shaped so that the respective radii of curvature satisfy the above-mentioned magnitude relationship. The cross-sectional shape of the wire of the tubular portion 10 formed by cutting (the cross-sectional shape along a direction perpendicular to the extending direction) is substantially rectangular and includes four faces. There are substantially no steps formed at the boundaries between the individual sections of the tubular section 10, and the individual sections are smoothly connected to each other. The material of the cylindrical portion 10 (single pipe) is not particularly limited, but examples thereof include Ni-Ti alloy and polylactic acid.

[0014] Each of the plurality of zigzag extension portions 20 is formed, for example, in a substantially circular ring shape extending 360 degrees around the circumference. The plurality of zigzag extension portions 20 are formed, for example, to have the same diameter as one another and are arranged coaxially with one another. Each of the multiple zigzag extension parts 20 has a zigzag shape in which a first extension part 22 extending in a direction inclined with respect to the axial direction (for example, a downward direction to the right in FIG. 1) and a second extension part 23 inclined in a direction opposite to the inclination direction of the first extension part 22 (an upward direction to the right in FIG. 1) are alternately and repeatedly connected. As shown in FIG. 4(c), the outer peripheral surface of the first extension part 22 and the outer peripheral surface of the second extension part 23 are in contact with, for example, a cylindrical shape 405. In each zigzag extension portion 20, a corner (first apex 25) of the boundary between one end (one end in the extension direction) of the first extension portion 22 and one end (same as above) of the second extension portion 23 adjacent to the first extension portion 22 has a convex shape toward the tip side, and a corner (second apex 27) of the boundary between the other end (other end in the extension direction) of the first extension portion 22 and the other end (same as above) of the second extension portion 23 adjacent to the first extension portion 22 has a convex shape toward the base end side. The first apex 25 and the second apex 27 have, for example, the same shape as each other and are disposed symmetrically in the axial direction. 3, the first apex 25 has a shape including a circular arc (for example, a circular arc with a central angle of about 180 degrees), and the shape when viewed in the radial direction is a shape obtained by upside down inverting a U. One end of the first apex 25 and one end of the first extension portion 22 are connected, and the other end of the first apex 25 and one end of the second extension portion 23 are connected. Similarly, the second apex 27 has a shape including a substantially arc shape (for example, an arc with a central angle of about 180 degrees), and the shape when viewed in the radial direction is substantially U-shaped. One end of the second apex 27 and the other end of the first extension portion 22 are connected, and the other end of the first apex 25 and the other end of the second extension portion 23 are connected. However, in the present invention, the shapes of each of the first apex 25 and the second apex 27 are not limited to this example. Each of the first apex 25 and the second apex 27 may be formed, for example, in a circular shape when viewed in the radial direction, or may be formed in an angular shape formed by the intersection of two straight lines.

[0015] As shown in FIG. 1, in this embodiment, the multiple zigzag extension portions 20 are arranged so that the first apex 25 of one zigzag extension portion 20 and the second apex 27 of another zigzag extension portion 20 adjacent to the zigzag extension portion 20 are close to each other in the axial direction. In this case, "close to each other" means that the distance between the apex 25a of the first apex 25 and the apex 27a of the second apex 27 in the axial direction is less than or equal to the length dimension (axial dimension) of the zigzag extension portion 20, and the distance between the first apex 25 and the second apex 27 in the circumferential direction is less than or equal to the width dimension of the first extension portion 22 in the circumferential direction. However, the present invention is not limited to this example, and the multiple zigzag extension portions 20 may be arranged so that the first apex 25 of one zigzag extension portion 20 and the first apex 25 of another zigzag extension portion 20 adjacent to the zigzag extension portion 20 are close to each other in the axial direction, and the second apex 27 of one zigzag extension portion 20 and the second apex 27 of the other zigzag extension portion 20 adjacent to the zigzag extension portion 20 are close to each other in the axial direction.

[0016] In this embodiment, in the multiple zigzag extension portions 20, the length dimension (dimension in the extension direction) of each first extension portion 22 and the length dimension (same as above) of each second extension portion 23 are set to, for example, the same length dimensions as each other. Moreover, the first extension portions 22 are set to have the same length dimension, and the second extension portions 23 are also set to have the same length dimension. In the plurality of zigzag extending portions 20, the inclination angle of the first extending portion 22 with respect to the axis of the tubular portion 10 and the inclination angle of the second extending portion 23 with respect to the axis are set to be equal to each other. Further, the inclination angles of the first extension portions 22 are set to be equal to each other, and the inclination angles of the second extension portions 23 are also set to be equal to each other. The first apex 25 and the second apex 27 are formed to have, for example, the same shape and the same dimensions as each other. That is, the first apex 25 and the second apex 27 have, for example, the same arc lengths and the same central angles. However, in the present invention, for example, in the multiple zigzag extension parts 20, the first extension parts 22 and the second extension parts 23 may be set to have the same length dimension (dimension in the extension direction) and inclination angle, or may be set to different length dimensions and inclination angles. Furthermore, each of the first extension parts 22 may be set to have the same length dimension and inclination angle, or may be set to different length dimensions and inclination angles. Similarly, each of the second extension parts 23 may be set to have the same length dimension and inclination angle, or may be set to different length dimensions and inclination angles. In the present invention, the first apex 25 and the second apex 27 may be formed to have, for example, different shapes and different dimensions from each other. That is, the first apex 25 and the second apex 27 may have, for example, different arc lengths or different central angles from each other. Furthermore, in the present invention, the number of the zigzag extending portions 20 of the tubular portion 10 is not particularly limited, and can be changed appropriately depending on the desired dimensions and applications of each portion of the stent 100.

[0017] Here, as described above, the zigzag extending portions 20 adjacent to each other in the axial direction are connected to each other by the connecting portions 30 . In this embodiment, as shown in Fig. 7, the connection portion 30 is contained inside a virtual cylindrical shape 405 that envelops, with a minimum diameter, an assembly of the multiple zigzag extension portions 20. For convenience, Fig. 7 shows a schematic and simplified view of the shape of the connection portion 30 as viewed in the axial direction. In addition, "being contained inside" here means that the entire connecting portion 30 is substantially contained inside the radial direction of a virtual cylindrical shape 405 that envelops the assembly of the multiple zigzag extending portions 20 with a minimum diameter. Furthermore, "substantially contained" means that at least the entire inner peripheral surface of the connecting portion 30 is contained inside the radial direction of the virtual cylindrical shape 405. In the case of this embodiment, for example, the outer peripheral surface of the connecting portion 30 is in contact with the cylindrical shape 405 as shown in FIG. 7. However, in the present invention, for example, a part of the wall thickness of the connecting portion 30 may overlap with the cylindrical shape 405. With this configuration, it is possible to more reliably prevent the connection portion 30 from getting caught on the inner wall surface of the biological lumen 300, compared to when the connection portion 30 protrudes radially outward from the imaginary cylindrical shape 405. More specifically, in the case of the present embodiment, in the tubular portion 10, one zigzag extension portion 20 and another zigzag extension portion 20 adjacent to the zigzag extension portion 20 are connected to each other by a plurality of (e.g., three) connection portions 30. Each connection portion 30 is contained inside a virtual tubular shape 405 that envelops the assembly of the plurality of zigzag extension portions 20 with a minimum diameter. 7, the multiple connection portions 30 connecting adjacent zigzag extension portions 20 are disposed at positions offset from one another in the radial direction with respect to the center of the tubular portion 10. Moreover, the connection portions 30 are formed to have the same shape as one another and are disposed in rotational symmetry with respect to one another with respect to the center of the tubular portion 10. In this manner, each of the multiple zigzag extension portions 20 included in the tubular portion 10 is connected to one another by the connection portions 30 . In the present invention, the number of connecting portions 30 that the tubular portion 10 has is not particularly limited, as long as adjacent zigzag extending portions 20 are connected to each other by at least one connecting portion 30 .

[0018] In this embodiment, the connection portion 30 connects the first extension portion 22 of one zigzag extension portion 20 to the first extension portion 22 of another zigzag extension portion 20 that faces the first extension portion 22 in the axial direction. However, the present invention is not limited to this example. For example, the connection portion 30 may connect the second extension portion 23 of one zigzag extension portion 20 to the second extension portion 23 of another zigzag extension portion 20 that faces the second extension portion 23 in the axial direction, or may connect the first extension portion 22 of one zigzag extension portion 20 to the second extension portion 23 of another zigzag extension portion 20 that is close to the first extension portion 22. In addition, as in Modification 2 described later, the connection portion 30 may connect the first apex 25 of one zigzag extension portion 20 to the second apex 27 of another zigzag extension portion 20 that faces the first apex 25 in the axial direction.

[0019] One end 31 and the other end 32 of the connection part 30 (one end and the other end in the extending direction) each extend linearly along the axial direction. The one end 31 and the other end 32 are disposed at positions offset from each other in the circumferential direction. The intermediate portion 33 (the intermediate portion in the extending direction) of the connecting portion 30 extends linearly in a direction (e.g., a direction upward to the right in FIG. 3) intersecting each of the one end portion 31 and the other end portion 32. One end (one end in the circumferential direction) of the intermediate portion 33 is connected to the base end of the one end portion 31, and the other end (the other end in the circumferential direction) of the intermediate portion 33 is connected to the tip end of the other end portion 32. In this manner, the intermediate portion 33 connects the base end of the one end portion 31 and the tip end of the other end portion 32 to each other. The one end 31 and the other end 32 are set to have, for example, the same length dimension. The length dimension of each of the one end 31 and the other end 32 is greater than the length dimension of the intermediate portion 33. When viewed in the axial direction, the overall shape of the intermediate portion 33 is formed into a generally arcuate shape that is convex radially outward. In the circumferential direction of the tubular portion 10, each of the two ends of the intermediate portion 33 is disposed closer to the inside of the tubular shape 405 than the center of the intermediate portion 33. One end portion 31 extends from the corresponding first extension portion 22 toward one end (one end in the circumferential direction) of the intermediate portion 33 while being gradually displaced radially inward. Similarly, the other end portion 32 extends from the corresponding first extension portion 22 toward the other end (the other end in the circumferential direction) of the intermediate portion 33 while being gradually displaced radially inward. In this way, the entire connecting portion 30 is contained inside an imaginary cylindrical shape 405 that envelops the assembly of the multiple zigzag extension portions 20 with a minimum diameter.

[0020] In this embodiment, in the zigzag extension portion 20, the radius of curvature of each of the first apex 25 and the second apex 27 is the smallest, and the radius of curvature of each of the first apex 25 and the second apex 27 is, for example, equal to the radius of curvature of the connection portion 30. Here, "equal" means that the radius of curvature of the connection portion 30 is at least 0.9 times and 1.1 times the radius of curvature of the first apex portion 25 (or the second apex portion 27). In the zigzag extension portion 20, the first extension portion 22 and the second extension portion 23 each have the largest radius of curvature. More specifically, in a cut surface ( FIG. 4(b) ) along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the intermediate portion 33 is smaller than the radius of curvature of the zigzag extension portion 20. Note that, in FIG. 4(b) , a cut surface along line BB of the intermediate portion 33 is shown as an example, but the radius of curvature of other portions of the connection portion 30 is also smaller than the radius of curvature of the zigzag extension portion 20. 4(c), in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the first extension portion 22 and the radius of curvature of the second extension portion 23 are each larger than the radius of curvature of the connection portion 30. Note that, in FIG. 4(c), the cross section taken along line CC of the first extension portion 22 and the second extension portion 23 is shown as an example, but the radius of curvature of other portions of the first extension portion 22 and the second extension portion 23 is also larger than the radius of curvature of the connection portion 30. Here, "large" means that the radius of curvature of the first extension portion 22 (or the second extension portion 23) is at least 1.1 times the radius of curvature of the intermediate portion 33 in the circumferential direction of the tubular portion 10. In addition, in a cross section ( FIG. 4(a) ) taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the first apex 25 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Note that, in FIG. 4(a) , a cross section taken along line AA of the first apex 25 is shown as an example, but the radius of curvature of other portions of the first apex 25 is also smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Similarly, although not shown, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the second apex 27 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Furthermore, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the intermediate portion 33 of the connecting portion 30 is equal to the radius of curvature of the first apex portion 25 and the radius of curvature of the second apex portion 27.

[0021] However, in the present invention, the relationship between the radii of curvature at each portion of the zigzag extension portion 20 and the connection portion 30 is not limited to the above example, and it is sufficient that the radius of curvature of the connection portion 30 is set to be smaller than the radius of curvature of the zigzag extension portion 20, at least in the circumferential direction of the tubular portion 10.

[0022] In this embodiment, the tubular portion 10 has, in addition to the plurality of zigzag extending portions 20 described above, an end winding portion 40 located at one end in the axial direction (the tip in this embodiment). As shown in FIG. 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 the valleys 44 are alternately arranged in the circumferential direction. Each of the plurality of peaks 42 is formed in a V-shape that protrudes toward the distal end side. Each of the plurality of valleys 44 is formed in a V-shape that protrudes toward the proximal end side. Furthermore, as shown in FIG. 1, end turns 40 may include, for example, struts 46 interconnecting peaks 42 and valleys 44 adjacent to peaks 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 .

[0023] Here, the stent 100 is, as an example, a covered stent having a tubular resin film 50 attached along the stent 100 . The resin film 50 is formed to be longer in the axial direction than the tubular portion 10. The tip of the resin film 50 protrudes from the tip side of the tubular portion 10, and this protruding portion constitutes the check valve portion 52. The check valve portion 52 allows flow to one side (e.g., the base end side) in the axial direction of the tubular portion 10 within the stent 100, while restricting flow to the opposite side (e.g., the tip side). The resin film 50 is also provided with a marker portion 54. The marker portion 54 is disposed on the distal side of the middle (middle in the axial direction) of the resin film 50 and on the proximal side of the end winding portion 40. When placing the stent 100, the distal end of the stent 100 can be positioned with respect to the biological lumen using the marker portion 54 as an index (for example, so that the distal end of the stent 100 protrudes from the biological lumen by a desired length). In FIG. 1, the arrangement area of ​​the marker portion 54 is indicated by a plurality of dots. The resin film 50 is made of a resin material such as silicone rubber. As an example, the resin film 50 is formed by impregnating the cylindrical portion 10 with a resin material, and is a cylindrical film in the same layer as the cylindrical portion 10. The marker portion 54 is formed, for example, by applying a liquid elastomer to the resin film 50 and drying it. However, the present invention is not limited to this example, and the marker portion 54 may be a reinforcing tape made of a resin material and having an adhesive layer, or a ring made of metal or resin. In the present invention, the stent 100 does not necessarily have to include the resin film 50, and may be, for example, a bare stent.

[0024] Furthermore, in this embodiment, the stent 100 has a covering portion that covers the tubular portion 10 . As described above, since the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extending portion 20 in the circumferential direction of the tubular portion 10, it is possible to suppress interference of the connecting portion 30 with the covering portion. Furthermore, it is possible to suppress the connecting portion 30 from getting caught on the covering portion when the covering portion is placed on the tubular portion 10, so that it is possible to improve the ease of manufacturing the stent 100. In this embodiment, the covering portion is a covering film 60 formed in a cylindrical shape and sheathing the tubular portion 10. The covering film 60 is disposed coaxially with the tubular portion 10. The covering film 60 is configured to be capable of contracting in diameter as the stent 100 contracts in diameter, and to be capable of expanding in diameter as the stent 100 expands in diameter. The inner diameter of the covering film 60 and the outer diameter of the tubular portion 10 are equal to each other. The material constituting the covering film 60 is not particularly limited, but examples include silicone rubber, urethane, polyethylene, and polytetrafluoroethylene.

[0025] As shown in FIG. 6, the outer circumferential surface of the connecting portion 30 may be formed with a plurality of narrow grooves 29 extending in a direction that includes an axial component, for example. According to this configuration, the outer peripheral surface of the connection portion 30 includes irregularities extending in a direction that includes an axial component, thereby ensuring adhesion of the covering film 60 to the outer peripheral surface of the connection portion 30. The narrow grooves 29 may extend in the same direction or in different directions, and may have the same dimensions or different dimensions. The width dimension (dimension in a direction perpendicular to the extending direction) of the plurality of narrow grooves 29 is, for example, preferably 1 μm or more and 150 μm or less, and more preferably 1 μm or more and 100 μm or less. The length dimension of the plurality of narrow grooves 29 is, for example, preferably not less than 10 μm and not more than 200 μm, and more preferably not less than 50 μm and not more than 150 μm.

[0026] <Variation 1> Next, a stent 100 according to Modification 1 will be described with reference to FIG. 8 to FIG. 9(c). The stent 100 according to this modification differs from the stent 100 according to the above embodiment in the points described below, and is otherwise configured similarly to the stent 100 according to the above embodiment. Fig. 8 is a diagram showing the stent 100 cut along its axial direction at one point in the circumferential direction and laid out flat, and the left-right direction in Fig. 8 corresponds to the circumferential direction of the stent 100.

[0027] In this modified example, the connection portion 30 has end connection portions 35 that connect both ends of the connection portion 30 in the circumferential direction. The two-end connection portion 35 has a straight portion 36 that is linear when viewed in the radial direction, and bent portions 38 that are bent and connected to both ends (one end 36a and the other end 36b) of the straight portion 36, respectively. With this configuration, the connection portion 30 can have both appropriate elasticity and shape retention, so that the connection portion 30 can smoothly follow the contraction or expansion of the diameter of the stent 100 while maintaining the state in which the multiple zigzag extension portions 20 are connected to each other.

[0028] In the case of this modified example, the intermediate portion 33 constitutes the both-end connection portion 35. Therefore, the both-end connection portion 35 connects the base end of the one end portion 31 and the tip end of the other end portion 32 to each other. Each of the one end 31 and the other end 32 is inclined, for example, in a direction intersecting the axial direction (for example, a downward left direction in FIG. 8). The one end 31 and the other end 32 are arranged on the same straight line. The straight portion 36 is inclined, for example, in a direction intersecting with each of the one end portion 31 and the other end portion 32 (for example, in a direction rising to the right in FIG. 8). One end 36a of the straight portion 36 is connected to a bent portion 38a, and the other end 36b of the straight portion 36 is connected to a bent portion 38b. Furthermore, the bent portion 38a is connected to the base end of the one end portion 31, and the bent portion 38b is connected to the tip end of the other end portion 32. The bent portion 38a and the bent portion 38b are, for example, symmetrical to each other in the axial direction with the straight portion 36 as the reference. More specifically, the boundary between one end 36a of the straight portion 36 and the bent portion 38a has a convex arc shape in a direction including one component in the circumferential direction (e.g., the right in FIG. 8). The boundary between the other end 36b of the straight portion 36 and the bent portion 38b has a convex arc shape in a direction including one component in the circumferential direction (e.g., the left in FIG. 8). The boundary between the base end of one end 31 and the bent portion 38a has a convex arc shape in a direction including one component in the circumferential direction (e.g., diagonally downward left in FIG. 8). The boundary between the tip of the other end 32 and the bent portion 38b has a convex arc shape in a direction including the other component in the circumferential direction (e.g., diagonally upward right in FIG. 8).

[0029] As shown in FIG. 9(b), in this modified example as well, the connection portion 30 is contained inside an imaginary cylindrical shape 405 that envelops the assembly of the multiple zigzag extending portions 20 with a minimum diameter. Also in this modified example, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extending portion 20 in a cross section taken along a direction perpendicular to the axis of the tubular portion 10 (FIG. 9(b)).

[0030] In this modified example, the radius of curvature of each of the first apex 25 and the second apex 27 in the zigzag extension portion 20 is the smallest, and the radius of curvature of each of the first apex 25 and the second apex 27 is, for example, equal to the radius of curvature of the connection portion 30. In the zigzag extension portion 20, the first extension portion 22 and the second extension portion 23 each have the largest radius of curvature. More specifically, in a cut surface ( FIG. 9(b) ) taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the intermediate portion 33 (connecting portions 35 at both ends) is smaller than the radius of curvature of the zigzag extending portion 20. Note that, in FIG. 9(b) , a cut surface taken along line BB of the intermediate portion 33 is shown as an example, but the radius of curvature of other portions of the connecting portion 30 is also smaller than the radius of curvature of the zigzag extending portion 20. In addition, in a cross section along a direction perpendicular to the axis of the tubular portion 10 shown in Figure 9 (c), the radius of curvature of the first extension portion 22 and the radius of curvature of the second extension portion 23 are each larger than the radius of curvature of the connection portion 30. 9(a) (for example, line AA shown in FIG. 8), the radius of curvature of the first apex 25 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Similarly, although not shown, the radius of curvature of the second apex 27 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23 in the cut surface along the direction perpendicular to the axis of the tubular portion 10. Furthermore, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the intermediate portion 33 of the connecting portion 30 is equal to the radius of curvature of the first apex portion 25 and the radius of curvature of the second apex portion 27.

[0031] <Variation 2> Next, a stent 100 according to Modification 2 will be described with reference to Figs. 10 to 11(c). The stent 100 according to this modification differs from the stent 100 according to the above embodiment in the points described below, and is otherwise configured similarly to the stent 100 according to the above embodiment. Fig. 10 is a diagram showing the stent 100 cut along its axial direction at one point in the circumferential direction and laid out flat, and the left-right direction in Fig. 10 corresponds to the circumferential direction of the stent 100.

[0032] In this modified example, the connection portion 30 connects adjacent vertices of the multiple zigzag extension portions 20. More specifically, the connection portion 30 connects a first apex 25 of one zigzag extension portion 20 to a second apex 27 of another zigzag extension portion 20 that faces the first apex 25 in the axial direction. In the present modified example, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extending portion 20 in the circumferential direction of the tubular portion 10 . This configuration can prevent both circumferential ends of the connection part 30 from getting caught on the inner wall surface of the biological lumen 300. Furthermore, when the connection part 30 expands and contracts as the diameter of the stent 100 expands, the connection part 30 is less likely to come into contact with the inner wall surface of the biological lumen 300, so that the expansion and contraction properties and flexibility of the stent 100 can be ensured. Therefore, the stent 100 can be placed at a desired site in the biological lumen 300 in a minimally invasive manner. It should be noted that the present invention is not limited to this example, and the connection portion 30 may, for example, connect a first apex 25 of one zigzag extension portion 20 to a first apex 25 of another zigzag extension portion 20 that faces the first apex 25 in the axial direction, or may connect a second apex 27 of one zigzag extension portion 20 to a second apex 27 of another zigzag extension portion 20 that faces the second apex 27 in the axial direction.

[0033] As shown in FIG. 11(b), in this modified example as well, the connection portion 30 is contained inside an imaginary cylindrical shape 405 that envelops the assembly of the multiple zigzag extension portions 20 with a minimum diameter. 10 and 11(b), in the present modified example, both ends (one end 30a and the other end 30b) of the connection part 30 are disposed closer to the inside of the cylindrical shape 405 than the central part 30c of the connection part 30 in the circumferential direction of the tubular part 10. In addition, in FIG. 11(b), for convenience, each cut surface (cut surface along a direction perpendicular to the axis of the tubular part 10) of both ends of the connection part 30 (both ends of the both end connection parts 35 in the present modified example) in the circumferential direction of the tubular part 10 is illustrated by a dashed line. According to such a configuration, both circumferential ends (one end 30a and the other end 30b) of the connection part 30 can be more reliably prevented from getting caught on the inner wall surface of the biological lumen 300 or the like. In this case, "located toward the inside" means that at least the outer peripheral surfaces of one end 30a and the other end 30b of the connecting portion 30 are located toward the inside (radially inward) of the cylindrical shape 405 relative to the outer peripheral surface of the central portion 30c.

[0034] In addition, in the present modified example, in the circumferential direction, the dimension of the connection portion 30 (dimension L2 shown in FIG. 10) is greater than the distance between adjacent vertices 25a, 27a of the zigzag extension portion 20 that are connected via the connection portion 30 (L1 shown in FIG. 10). With this configuration, the dimensions of the connection portion 30 in the circumferential direction can be sufficiently secured, so that it is easy to realize a state in which each of the two ends (one end 30a and the other end 30b) of the connection portion 30 is positioned closer to the inside of the tubular shape 405 than the central portion 30c of the connection portion 30 in the circumferential direction of the tubular portion 10. In this modified example, the dimension L2 of the connection portion 30 is, for example, preferably 1.1 to 5 times the distance L1 between the vertices 25a, 27a, and more preferably 1.5 to 3 times the distance L1.

[0035] In addition, in the case of this modified example, as shown in Figures 11(a) and 11(b), in the circumferential direction of the tubular portion 10, the radius of curvature of the adjacent vertices of the zigzag extension portion 20 and the radius of curvature of the connection portions 35 at both ends are equal to each other. In addition, the "close vertex portions of the zigzag extension portion 20" referred to here means the vertices of the zigzag extension portion 20 that are connected to each other by the connection portion 30, and in this modified example, it is the first vertex 25 and the second vertex 27 that are connected to each other via the connection portion 30. Moreover, the term "equal" here means that the radius of curvature of adjacent vertices of the zigzag extension portion 20 is 0.9 to 1.1 times the radius of curvature of the connection portions 35 at both ends. According to this configuration, there is no change in the radius of curvature at the connection part 30 and its vicinity, and stress can be distributed evenly at the connection part 30 and its vicinity when the stent 100 contracts or expands in diameter. Therefore, the shape of the connection part 30 and its vicinity can be well maintained (unintended deformation can be suppressed).

[0036] More specifically, as shown in FIG. 10, in this modified example, one end 31 of the connecting portion 30 is continuous with the first apex 25, and the other end 32 is continuous with the second apex 27. As shown in FIG. In the case of this modified example, the intermediate portion 33 constitutes the both-end connection portion 35. Therefore, the both-end connection portion 35 connects the base end of the one end portion 31 and the tip end of the other end portion 32 to each other. The intermediate portion 33 is formed, for example, in a straight line and is inclined in a direction intersecting the axial direction (for example, in a direction rising to the right in FIG. 10). Each of the one end portion 31 and the other end portion 32 is formed in a straight line, and is inclined in a direction intersecting with the intermediate portion 33 (for example, in a direction upward to the left in FIG. 10). The boundary between one end 31 and the intermediate portion 33 has a convex arc shape in a direction including one component in the circumferential direction (e.g., the right in FIG. 10). The boundary between the other end 32 and the intermediate portion 33 has a convex arc shape in a direction including one component in the circumferential direction (e.g., the left in FIG. 8). The length dimension of each of the one end portion 31 and the other end portion 32 is smaller than the length dimension of the intermediate portion 33, for example. As shown in FIG. 11(b), in the circumferential direction of the tubular portion 10, both ends (one ends 36a, 36b) of the end connection portion 35 are disposed closer to the inside of the tubular shape 405 than the central portion 30c of the connection portion 30. More specifically, the boundary between one end 36a of the two-end connection portion 35 and the base end of one end 31 protrudes further in the circumferential direction (e.g., to the right in FIG. 10) than the corresponding second apex 27, and constitutes one end 30a of the connection portion 30 in the circumferential direction. Similarly, the boundary between the other end 36b of the two-end connection portion 35 and the tip of the other end 32 protrudes further in the circumferential direction (e.g., to the left in FIG. 10) than the corresponding first apex 25, and constitutes the other end 30b of the connection portion 30 in the circumferential direction. In the case of this modified example, when viewed in the axial direction, the entire connecting portion 30 has an arc shape that is convex radially outward.

[0037] In this modified example, the radius of curvature of each of the first apex 25 and the second apex 27 in the zigzag extension portion 20 is the smallest, and the radius of curvature of each of the first apex 25 and the second apex 27 is, for example, equal to the radius of curvature of the connection portion 30. In the zigzag extension portion 20, the first extension portion 22 and the second extension portion 23 each have the largest radius of curvature. More specifically, in a cut surface along a direction perpendicular to the axis of the tubular portion 10 (see FIG. 11(b)), the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extension portion 20. Note that, in FIG. 11(b), a cut surface along line BB of the straight portion 36 is shown as an example, but in other parts of the connecting portion 30 as well, the radius of curvature of the outer circumferential surface is smaller than the radius of curvature of the annular zigzag extension portion 20. In addition, in a cross section along a direction perpendicular to the axis of the tubular portion 10 shown in Figure 11 (c), the radius of curvature of the first extension portion 22 and the radius of curvature of the second extension portion 23 are each larger than the radius of curvature of the connection portion 30. 11(a), the radius of curvature of the first apex 25 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Similarly, although not shown, the radius of curvature of the second apex 27 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23 in the cross section taken along a direction perpendicular to the axis of the tubular portion 10. Furthermore, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the connecting portion 30, the radius of curvature of the first apex portion 25, and the radius of curvature of the second apex portion 27 are equal to each other.

[0038] <Variation 3> Next, a stent 100 according to a third modification will be described with reference to FIG. 12 to FIG. 13(c). The stent 100 according to this modification differs from the stent 100 according to the above-mentioned modification 2 in the points described below, but in other points is configured similarly to the stent 100 according to the above-mentioned modification 2. Fig. 12 is a diagram showing the stent 100 cut along its axial direction at one point in the circumferential direction and laid out flat, and the left-right direction in Fig. 12 corresponds to the circumferential direction of the stent 100.

[0039] In this modified example, similarly to the modified example 2, the connection portion 30 connects the first apex 25 of one zigzag extension portion 20 to the second apex 27 of another zigzag extension portion 20 that faces the first apex 25 in the axial direction. However, in this modified example, the entire connection portion 30 is bent, and its shape when viewed in the radial direction is substantially S-shaped. As shown in FIG. 12, one end 31 of the connection portion 30 extends from the first apex 25 in a direction (diagonally upwards left in FIG. 12) that includes a component in the opposite direction (upward in FIG. 12) to the protruding direction of the second apex 27 (downward in FIG. 12), and the other end 32 of the connection portion 30 extends from the second apex 27 in a direction (diagonally downwards right in FIG. 12) that includes a component in the opposite direction (downward in FIG. 12) to the protruding direction of the first apex 25 (upward in FIG. 12). With this configuration, when the stent 100 is in an expanded diameter state, the relative axial displacement between adjacent zigzag extension portions 20 can be appropriately regulated by the connecting portions 30, thereby more reliably maintaining the axial length dimension of the stent 100 at the intended dimension.

[0040] More specifically, the connection portion 30 includes, for example, a first portion 39a having a convex arc shape toward one side in the circumferential direction (e.g., toward the left in FIG. 12), and a second portion 39b having a convex arc shape toward the other side in the circumferential direction (e.g., toward the right in FIG. 12). One end of the first portion 39a is connected to the first apex 25, and the other end of the first portion 39a is connected to one end of the second portion 39b. The other end of the second portion 39b is connected to the second apex 27. In this modification, one end 31 of the connection portion 30 is formed by one end of the first portion 39a, and the other end 32 of the connection portion 30 is formed by the other end of the second portion 39b. The middle portion 33 of the connection portion 30 is formed by the boundary between the first portion 39a and the second portion 39b. The first portion 39a and the second portion 39b are formed to have the same shape as each other and are disposed symmetrically in the circumferential direction. The radius of curvature of each of the first portion 39a and the second portion 39b (the radius of curvature of the arc-shaped portion) is, for example, larger than the radius of curvature of each of the first apex 25 and the second apex 27 (the radius of curvature of the arc-shaped portion). In this modification, the entire connecting portion 30 has a convex arc shape that faces radially outward when the tubular portion 10 is viewed in the axial direction. The entire connecting portion 30 is contained inside the tubular shape 405.

[0041] As shown in Fig. 13(b), in this modified example, the connection part 30 is also contained inside an imaginary cylindrical shape 405 that envelops the assembly of the multiple zigzag extension parts 20 with a minimum diameter. In the circumferential direction of the cylindrical part 10, each of the two ends (one end 30a, the other end 30b) of the connection part 30 is disposed closer to the inside of the cylindrical shape than the central part 30c of the connection part 30. In Fig. 13(b), for convenience, the cut surfaces (cut surfaces along a direction perpendicular to the axis of the cylindrical part 10) of each of the two ends of the connection part 30 are illustrated by dashed lines.

[0042] In this modified example, the radius of curvature of each of the first apex 25 and the second apex 27 in the zigzag extension portion 20 is the smallest, and the radius of curvature of each of the first apex 25 and the second apex 27 is, for example, equal to the radius of curvature of the connection portion 30. In the zigzag extension portion 20, the first extension portion 22 and the second extension portion 23 each have the largest radius of curvature. 13(b), in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extending portion 20. Note that, in FIG. 13(b), a cross section taken along line BB of the intermediate portion 33 is shown as an example, but in other parts of the connecting portion 30 as well, the radius of curvature of the outer circumferential surface is smaller than the radius of curvature of the annular zigzag extending portion 20. 13(a), the radius of curvature of the first apex 25 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Similarly, although not shown, the radius of curvature of the second apex 27 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23 in the cross section taken along a direction perpendicular to the axis of the tubular portion 10. Furthermore, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the connecting portion 30, the radius of curvature of the first apex portion 25, and the radius of curvature of the second apex portion 27 are equal to each other. In addition, in a cross section along a direction perpendicular to the axis of the tubular portion 10 shown in Figure 13 (c), the radius of curvature of the first extension portion 22 and the radius of curvature of the second extension portion 23 are each larger than the radius of curvature of the connection portion 30.

[0043] Also, in the case of this modified example, the dimension of the connection portion 30 in the circumferential direction (L2 shown in FIG. 12) is greater than the distance between adjacent vertices of the zigzag extension portions 20 connected via the connection portion 30 (L1 shown in FIG. 12).

[0044] <Modification 4> Next, a stent 100 according to a fourth modified embodiment will be described with reference to FIG. The stent 100 according to this modification differs from the stent 100 according to the above-mentioned modification 3 in the points described below, but is otherwise configured similarly to the stent 100 according to the above-mentioned modification 3. Fig. 12 is a diagram showing the stent 100 cut along its axial direction at one point in the circumferential direction and laid out flat, and the up-down direction in Fig. 12 corresponds to the circumferential direction of the stent 100.

[0045] In this modification, similarly to the third modification, the entire connecting portion 30 is bent, and its shape when viewed in the radial direction is substantially S-shaped. However, in this modified example, the connection portion 30 connects the first extension portion 22 of one zigzag extension portion 20 to the second extension portion 23 of another zigzag extension portion 20 that is adjacent to the first extension portion 22. Moreover, the radius of curvature of the first portion 39a is larger than the radius of curvature of the first portion 39a of the third modified example, and the radius of curvature of the second portion 39b is larger than the radius of curvature of the second portion 39b of the third modified example. In the case of this modified example, when the stent 100 expands in diameter, the relative axial displacement between adjacent zigzag extension portions 20 is appropriately regulated by the connecting portions 30, thereby more reliably allowing the stent 100 to extend by the intended amount of displacement.

[0046] <Variation 5> Next, a stent 100 according to a fifth modified example of the embodiment will be described with reference to Figs. 15 to 16(c). The stent 100 according to this modification differs from the stent 100 according to the above embodiment and modifications 1 to 4 in the points described below, but is otherwise configured similarly to the stent 100 according to the above embodiment and modifications 1 to 4. Fig. 15 is a diagram showing the stent 100 cut along its axial direction at one point in the circumferential direction and laid out flat, and the left-right direction in Fig. 15 corresponds to the circumferential direction of the stent 100.

[0047] In this modified example, the connection portion 30 connects the second extension portion 23 of one zigzag extension portion 20 to the second extension portion 23 of another zigzag extension portion 20 adjacent to the second extension portion 23, as in the above embodiment and modified examples 1 and 4. However, the entire intermediate portion 33 is bent as a whole like the connection portion 30 of modified example 3, and its shape when viewed in the radial direction is a shape of approximately S letters arranged at an angle.

[0048] The intermediate portion 33 includes, for example, a first portion 39a having a convex arc shape toward one side in the circumferential direction (for example, toward the left in FIG. 15), and a second portion 39b having a convex arc shape toward the other side in the circumferential direction (for example, toward the right in FIG. 15). The first portion 39a and the second portion 39b are formed to have the same shape as each other and are disposed symmetrically in the circumferential direction. The radius of curvature of each of the first portion 39a and the second portion 39b (the radius of curvature of the arc-shaped portion) is, for example, larger than the radius of curvature of each of the first apex 25 and the second apex 27 (the radius of curvature of the arc-shaped portion). Each of the one end 31 and the other end 32 extends linearly and is inclined in a direction intersecting the axial direction (for example, in a direction rising to the right in FIG. 15).

[0049] In this modified example as well, the connection portion 30 is contained inside an imaginary cylindrical shape 405 that envelops the assembly of the multiple zigzag extension portions 20 with a minimum diameter.

[0050] In this modified example, the radius of curvature of each of the first apex 25 and the second apex 27 in the zigzag extension portion 20 is the smallest, and the radius of curvature of each of the first apex 25 and the second apex 27 is, for example, equal to the radius of curvature of the connection portion 30. In the zigzag extension portion 20, the first extension portion 22 and the second extension portion 23 each have the largest radius of curvature. 16(b), in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the zigzag extending portion 20. Note that, in FIG. 16(b), a cross section taken along line BB of the intermediate portion 33 is shown as an example, but in other parts of the connecting portion 30 as well, the radius of curvature of the outer circumferential surface is smaller than the radius of curvature of the annular zigzag extending portion 20. Also, as shown in Figure 16 (c), in a cross section along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the first extension portion 22 and the radius of curvature of the second extension portion 23 are each larger than the radius of curvature of the connection portion 30. 16(a), in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the first apex 25 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Similarly, although not shown, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the second apex 27 is smaller than the radius of curvature of each of the first extension portion 22 and the second extension portion 23. Furthermore, in a cross section taken along a direction perpendicular to the axis of the tubular portion 10, the radius of curvature of the connecting portion 30, the radius of curvature of the first apex portion 25, and the radius of curvature of the second apex portion 27 are equal to each other.

[0051] The above describes the embodiments and each modified example with reference to the drawings. However, these are merely examples of the present invention, and the present invention is not limited to the above-described embodiments and each modified example, but also includes various modifications, improvements, and other aspects as long as the object of the present invention is achieved.

[0052] Furthermore, the various components of stent 100 do not need to be independent entities, but rather it is acceptable for multiple components to be formed as a single member, for one component to be formed from multiple members, for one component to be a part of another component, or for part of one component to overlap with part of another component, etc.

[0053] The present embodiment encompasses the following technical ideas. (1) A stent having a tubular portion, The cylindrical portion is The cylindrical portion has a plurality of annular zigzag extending portions extending in a circumferential direction while swaying in a zigzag manner in an axial direction thereof, the zigzag extending portions being arranged offset from each other in the axial direction thereof, a connecting portion connecting adjacent ones of the zigzag extending portions in the axial direction, A stent in which, in the circumferential direction of the tubular portion, the radius of curvature of the connecting portion is smaller than the radius of curvature of the annular zigzag extending portion. (2) The stent according to (1), wherein the connection portion is contained within an imaginary cylindrical shape that envelops the assembly of the multiple zigzag extension portions with a minimum diameter. (3) A stent as described in (2), wherein in the circumferential direction of the tubular portion, each of the ends of the connection portion is positioned closer to the inside of the tubular shape than the center of the connection portion. (4) The connection portion has end connection portions connecting both ends of the connection portion in the circumferential direction, The two end connection portions are A straight portion having a straight shape when viewed in a radial direction; a bent portion connected to each end of the straight portion; The stent according to any one of (1) to (3), comprising: (5) The stent according to (4), wherein the radii of curvature of adjacent vertices of the zigzag extending portion in the circumferential direction of the tubular portion are equal to the radii of curvature of the connection portions at both ends. (6) A stent described in any one of (1) to (5), wherein in the circumferential direction, a dimension of the connection portion is greater than the distance between adjacent vertices of the zigzag extension portion that are connected via the connection portion. (7) A stent according to any one of (1) to (6), having a covering portion that covers the tubular portion. [Explanation of symbols]

[0054] 10 Cylindrical part 20 Multiple zigzag extensions 22 1st extension part 23 Second extension part 25 1st top 25a Vertex 27 Second top 27a Vertex 29 Narrow groove part 30 Connection 30a one end 30b Other end 30c central part 31 One end 32 Other end 33 Middle Section 35 Both ends connection 36 Straight section 36a one end 36b Other end 38 Bend 39a Part 1 39b Part 2 40 End winding part 42 Yamabe 44 Valley 46 Strut section 50 Resin Film 52 Check valve section 54 Marker section 60 Covering film (covering part) 100 Stents (covered stents) 300 Biological Lumen 401, 402: Zigzag extension portion arrangement area 405 Virtual Cylinder Shape

Claims

1. A stent having a tubular portion, The cylindrical portion is The cylindrical portion has a plurality of annular zigzag extending portions extending in a circumferential direction while swaying in a zigzag manner in an axial direction thereof, the zigzag extending portions being arranged offset from each other in the axial direction thereof, a connecting portion connecting adjacent ones of the zigzag extending portions in the axial direction, In a circumferential direction of the cylindrical portion, a radius of curvature of the connection portion is smaller than a radius of curvature of the annular zigzag extension portion, A stent in which the connection portion is contained inside an imaginary cylindrical shape that envelops the assembly of the plurality of zigzag extension portions with a minimum diameter.

2. The stent according to claim 1 , wherein each of the ends of the connection portion is disposed closer to the inside of the tubular shape than a center portion of the connection portion in a circumferential direction of the tubular portion.

3. The connection portion has end connection portions connecting both ends of the connection portion in the circumferential direction, The two end connection portions are A straight portion having a straight shape when viewed in a radial direction; a bent portion connected to each end of the straight portion; 3. The stent according to claim 1 or 2, comprising:

4. The stent according to claim 3 , wherein the radii of curvature of adjacent vertices of the zigzag extending portion in the circumferential direction of the tubular portion are equal to the radii of curvature of the connection portions at both ends.

5. The stent according to claim 1 or 2, wherein a dimension of the connection portion in the circumferential direction is greater than a distance between adjacent vertices of the zigzag extension portions that are connected via the connection portion.

6. The stent according to claim 1 or 2, further comprising a covering portion which covers the tubular portion.

Images