stent

Abstract

To provide a stent that can be more easily placed within a biological lumen. [Solution] The stent 100 is a stent having a cylindrical portion 10, and the cylindrical portion 10 has a plurality of annular zigzag extensions 20 that extend in the circumferential direction while oscillating in a zigzag pattern in the axial direction of the cylindrical portion 10, arranged in an offset manner from one another in the axial direction, and has connecting portions 30 that connect adjacent zigzag extensions 20 in the axial direction, and in the circumferential direction of the cylindrical portion 10, the radius of curvature of the connecting portions 30 is smaller than the radius of curvature of the annular zigzag extensions 20.

Description

Technical Field

[0001] The present invention relates to a stent.

Background Art

[0002] As a stent used by being placed in a biological lumen, for example, there is one described in Patent Document 1. The stent of Patent Document 1 has a cylindrical portion, and a plurality of annular zigzag extending portions that extend in the circumferential direction while zigzagging in the axial direction of the cylindrical portion are arranged so as to be displaced from each other in the axial direction.

Document of Prior Art

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the study of the inventor of the present application, there is still room for improvement in the ease of placing the stent of Patent Document 1 in a biological lumen.

Means for Solving the Problems

[0005] According to the present invention, there is provided a stent having a cylindrical portion, wherein the cylindrical portion has a plurality of annular zigzag extending portions that extend in the circumferential direction while zigzagging in the axial direction of the cylindrical portion, and the plurality of them are arranged so as to be displaced from each other in the axial direction, and has a connecting portion connecting the adjacent zigzag extending portions in the axial direction, and a stent is provided in which, 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.

Effects of the Invention

[0006] According to the present invention, stents can be more easily placed within the lumen of a living organism. [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 partially enlarged perspective view of the connection portion and its surrounding structure in the embodiment. [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. [Figure 4] Figure 4(a) is a cross-sectional view along line AA shown in Figure 3, Figure 4(b) is a cross-sectional view along line BB shown in Figure 3, and Figure 4(c) is a cross-sectional view along line CC shown in Figure 3. [Figure 5] Figure 5(a) is a schematic diagram of the connection part in the embodiment, and Figure 5(b) is a partially enlarged view of Figure 5(a). [Figure 6] This is a magnified view of part A shown in Figure 3. [Figure 7] This is a cross-sectional view of a stent according to an embodiment, showing it in a state where it is placed in a biological lumen. [Figure 8] This is a magnified view of the connection part and its surrounding structure in Modification Example 1, showing the stent in a flat, unfolded state and in an expanded state. [Figure 9] Figure 9(a) is a cross-sectional view along line AA shown in Figure 8, Figure 9(b) is a cross-sectional view along line BB shown in Figure 8, and Figure 9(c) is a cross-sectional view along line CC shown in Figure 8. [Figure 10] This is a magnified view of the connection part and its surrounding structure in Modification 2, showing the stent in a flat, unfolded state and in an expanded state. [Figure 11] Figure 11(a) is a cross-sectional view along line AA shown in Figure 10, Figure 11(b) is a cross-sectional view along line BB shown in Figure 10, and Figure 11(c) is a cross-sectional view along line CC shown in Figure 10. [Figure 12]This is a partially enlarged view of the connection part and its surrounding structure in Modification Example 3, showing the stent in a flat, unfolded state and in an expanded state. [Figure 13] Figure 13(a) is a cross-sectional view along line AA shown in Figure 12, Figure 13(b) is a cross-sectional view along line BB shown in Figure 12, and Figure 13(c) is a cross-sectional view along line CC shown in Figure 12. [Figure 14] This is a partially enlarged view of the connection part and its surrounding structure in Modification 4, showing the stent in a flat, unfolded state and in an expanded state. [Figure 15] This is a magnified view of the connection part and its surrounding structure in Modification 5, showing the stent in a flat, unfolded state and in an expanded state. [Figure 16] Figure 16(a) is a cross-sectional view along line AA shown in Figure 15, Figure 16(b) is a cross-sectional view along line BB shown in Figure 15, and Figure 16(c) is a cross-sectional view along line CC shown in Figure 15. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to Figures 1 to 7. In all drawings, similar components are denoted by the same reference numeral, and explanations are omitted where appropriate. The axial direction of the stent 100 is the vertical direction in Figure 1. Figure 3 shows the stent 100 cut along its axial direction at one point in the circumferential direction and laid flat. The left-right direction in Figure 3 corresponds to the circumferential direction of the stent 100. Also, in Figure 1, the shapes of the multiple zigzag extensions 20 are shown in a simplified manner. Figure 7 shows the stent 100 in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10.

[0009] The stent 100 according to this embodiment is a stent having a cylindrical portion 10. The cylindrical portion 10 has a plurality of annular zigzag extending portions 20 that extend in the circumferential direction while zigzagging in the axial direction of the cylindrical portion 10, and the plurality of zigzag extending portions 20 are arranged so as to be offset from each other in the axial direction, and also has a connecting portion 30 that connects the adjacent zigzag extending portions 20 in the axial direction. As shown in FIG. 4(b), in the circumferential direction of the cylindrical 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, a more detailed explanation will be given about the "radius of curvature of the connecting portion 30". First, when the cylindrical portion 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 peripheral surface of the connecting portion 30 in the circumferential direction are defined as P1, P2, P3, P4, P5, P6, P7, P8, P9, P10 (see FIGS. 5(a) and 5(b)). In FIGS. 5(a) and 5(b), for the sake of convenience, the shape of the connecting portion 30 viewed in the axial direction is schematically and simplifiedly illustrated. Next, a point equidistant from P1 to P3 is defined as C1 (see FIG. 5(b)), and the radial separation distance between P1 to P3 and C1 is defined as R1. Similarly, a point equidistant from P2 to P4 is defined as C2, and the radial separation distance between P2 to P4 and C2 is defined as R2. A point equidistant from P3 to P5 is defined as C3, and the radial separation distance between P3 to P5 and C3 is defined as R3. A point equidistant from P4 to P6 is defined as C4, and the radial separation distance between P4 to P6 and C4 is defined as R4. A point equidistant from P5 to P7 is defined as C5, and the radial separation distance between P5 to P7 and C5 is defined as R5. A point equidistant from P6 to P8 is defined as C6, and the radial separation distance between P6 to P8 and C6 is defined as R6. A point equidistant from P7 to P9 is defined as C7, and the radial separation distance between P7 to P9 and C7 is defined as R7. A point equidistant from P8 to P10 is defined as C8, and the radial separation distance between P8 to P10 and C8 is defined as R8. The average value of the separation distances R1 to R8 obtained in this way is defined as the "radius of curvature of the connecting portion 30". Similarly, the "radius of curvature of the zigzag extending portion 20" is the average value of the radial separation distances R1 to R8 between C1 to C8 corresponding to a plurality of points P1 to P10 plotted at equal intervals from one end to the other end of the outer peripheral surface of the zigzag extending portion 20 when the cylindrical portion 10 is viewed in the axial direction in the circumferential direction. In the present invention, "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 cylindrical portion 10" means that the radius of curvature of the zigzag extending portion 20 calculated as described above is at least 1.1 times or more, preferably 1.2 times or more, more preferably 1.5 times or more, and still more preferably 3 times or more the radius of curvature of the connecting portion 30. Therefore, as long as this condition is satisfied, the radius of curvature of a part of the connecting portion 30 may be equal to or larger than the radius of curvature of the zigzag extending portion 20 in the circumferential direction of the cylindrical portion 10. Further, the "displaced arrangement in the axial direction" as referred to herein means that in the expanded state of the stent 100, the arrangement region 401 (see FIG. 1) of one zigzag extending portion 20 and the arrangement region 402 (see FIG. 1) of another zigzag extending portion 20 adjacent to the zigzag extending portion 20 may overlap or not overlap each other in the axial direction. However, when the arrangement region 401 of one zigzag extending portion 20 and the arrangement region 402 of another zigzag extending portion 20 overlap each other, they are arranged at positions where the zigzag shapes of these zigzag extending portions 20 do not cross 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 contracted state while housed within the outer sheath (not shown) of the stent placement device. When the tip of the outer sheath containing the stent 100 is delivered to the placement site in the biological lumen 300 (see Figure 7), and the stent 100 is detached from the outer sheath, the stent 100 elastically recovers from its contracted state to its expanded state. In this way, the stent 100 can be transported and placed at the placement site in the biological lumen 300. The contracted state of stent 100 refers to a state in which stent 100 is compressed radially to the extent that it can remain within the outer sheath. The expanded state of stent 100 refers to a state in which it is at least larger than the contracted state, for example, the natural state of stent 100. In Figures 1 to 7, stent 100 is shown in the expanded state (natural state).

[0011] In this embodiment, in the circumferential direction of the cylindrical portion 10, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extension portion 20. With this configuration, it is possible to prevent the circumferential ends of the connecting portion 30 from getting caught on the inner wall surface of the biological lumen 300. Furthermore, as the diameter of the stent 100 expands and contracts, the connecting portion 30 becomes less likely to come into contact with the inner wall surface of the biological lumen 300, thus ensuring the expandability and flexibility of the stent 100. Therefore, the stent 100 can be more easily placed within the biological lumen 300.

[0012] In the following description, the circumferential direction of the cylindrical portion 10 may be simply referred to as the circumferential direction, the axial direction of the cylindrical portion 10 as the axial direction, and the radial direction of the cylindrical portion 10 as the radial direction. Also, for convenience, one side in the axial direction (one end (upward direction in Figure 1)) will be referred to as the tip side, and the other side in the axial direction (the other end (downward direction in Figure 1)) will be referred to as the base end side. Furthermore, unless otherwise specified, the positional relationships and shapes of the various parts of the stent 100 describe the positional relationships and shapes of the stent 100 in its expanded diameter state.

[0013] 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). When forming the cylindrical portion 10, the radii of curvature of each of the multiple zigzag extensions 20 and connecting portions 30 are shaped to have the above-mentioned relationship. The cross-sectional shape of the wire of the cylindrical portion 10 formed by cutting (the cross-sectional shape along the direction perpendicular to the extension direction) 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.

[0014] 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. As shown in Figure 4(c), the outer circumferential surfaces of the first extension 22 and the second extension 23 are in contact with the cylindrical shape 405, for example. 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 tip side, and the corner (second apex 27) 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 base end side. The first vertex 25 and the second vertex 27 are, for example, identical in shape and arranged symmetrically in the axial direction. More specifically, as shown in Figure 3, the first vertex 25 has a shape that includes a circular arc (for example, a circular arc with a central angle of approximately 180 degrees), and its shape when viewed radially is roughly an inverted U shape. One end of the first vertex 25 is connected to one end of the first extension 22, and the other end of the first vertex 25 is connected to one end of the second extension 23. Similarly, the second vertex 27 has a shape that includes a roughly circular arc (for example, a circular arc with a central angle of approximately 180 degrees), and its shape when viewed radially is roughly U-shaped. One end of the second vertex 27 is connected to the other end of the first extension 22, and the other end of the first vertex 25 is connected to the other end of the second extension 23. However, in the present invention, the shapes of the first vertex 25 and the second vertex 27 are not limited to this example. Each of the first vertex 25 and the second vertex 27 may, for example, be formed in a circular shape when viewed radially, or it may be angular in shape formed by the intersection of two straight lines.

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

[0016] 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 27 are formed to be, for example, identical in shape and dimensions. That is, the first vertex 25 and the second vertex 27 have, for example, equal arc lengths and equal central angles. 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 vertex 25 and the second vertex 27 may be formed with different shapes and dimensions, for example. That is, the first vertex 25 and the second vertex 27 may have different arc lengths or different central angles. 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.

[0017] Here, as described above, adjacent zigzag extensions 20 in the axial direction are connected by connecting parts 30. In this embodiment, as shown in Figure 7, the connecting portion 30 is housed inside a virtual cylindrical shape 405 that encloses the aggregate of multiple zigzag extensions 20 with the smallest diameter. Note that in Figure 7, for convenience, the shape of the connecting portion 30 as viewed in the axial direction is shown schematically and simply. In this context, "fitting inside" means that the entire connecting portion 30 is substantially fitted radially inside the virtual cylindrical shape 405 that encloses the collection of multiple zigzag extensions 20 with the minimum diameter. Furthermore, "substantially fitted" means that at least the entire inner circumferential surface of the connecting portion 30 is fitted radially inside the virtual cylindrical shape 405. In this embodiment, for example, as shown in Figure 7, the outer circumferential surface of the connecting portion 30 is in contact with the cylindrical shape 405. However, in this invention, for example, a portion of the wall thickness of the connecting portion 30 may overlap with the cylindrical shape 405. With this configuration, compared to the case where the connecting portion 30 protrudes radially outward from the virtual cylindrical shape 405, it is possible to more reliably prevent the connecting portion 30 from getting caught on the inner wall surface of the biological lumen 300 or the like. More specifically, in this embodiment, in the cylindrical portion 10, one zigzag extension 20 and other zigzag extensions 20 adjacent to that zigzag extension 20 are connected to each other by a plurality (for example, three) of connecting portions 30. Each connecting portion 30 is housed inside a virtual cylindrical shape 405 that encloses the collection of the plurality of zigzag extensions 20 with a minimum diameter. As shown in Figure 7, the multiple connecting portions 30 that connect adjacent zigzag extensions 20 are positioned at radially offset positions from each other with respect to the center of the cylindrical portion 10. Furthermore, each connecting portion 30 is formed to be the same shape as the others and is arranged rotationally symmetrically with respect to the center of the cylindrical portion 10. In this way, each of the multiple zigzag extensions 20 included in the cylindrical portion 10 is connected to one another by the connecting portion 30. In this invention, the number of connecting portions 30 in 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.

[0018] In this embodiment, the connecting portion 30 connects the first extending portion 22 of one zigzag extending portion 20 to the first extending portion 22 of another zigzag extending portion 20 that is facing the first extending portion 22 in the axial direction. However, the present invention is not limited to this example. For example, the connecting portion 30 may connect a second extending portion 23 of one zigzag extending portion 20 to a second extending portion 23 of another zigzag extending portion 20 that is axially opposite to the second extending portion 23 of the first extending portion 23 of the first zigzag extending portion 20, or it may connect a first extending portion 22 of one zigzag extending portion 20 to a second extending portion 23 of another zigzag extending portion 20 that is adjacent to the first extending portion 22 of the first extending portion 22 of the first extending portion 22 of the first zigzag extending portion 20. Furthermore, as shown in Modification 2 described later, the connecting portion 30 may connect a first apex 25 of one zigzag extending portion 20 to a second apex 27 of another zigzag extending portion 20 that is axially opposite to the first apex 25 of the first zigzag extending portion 20.

[0019] The one end 31 and the other end 32 of the connecting portion 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 positioned offset from each other in the circumferential direction. The intermediate portion 33 of the connecting portion 30 (the intermediate portion in the extending direction) extends linearly in a direction intersecting each of the one end portion 31 and the other end portion 32 (for example, the upward-sloping direction in Figure 3). One end of the intermediate portion 33 (one end in the circumferential direction) is connected to the base end of the one end portion 31, and the other end of the intermediate portion 33 (the other end in the circumferential direction) is connected to the tip of the other end portion 32. In this way, the intermediate portion 33 connects the base end of the one end portion 31 and the tip of the other end portion 32 to each other. One end 31 and the other end 32 are set to, for example, equivalent lengths. The length of each end 31 and the other end 32 is greater than the length of the intermediate section 33. When viewed in the axial direction, the overall shape of the intermediate portion 33 is formed in a roughly arc shape that is convex radially outward. In the circumferential direction of the cylindrical portion 10, each of the ends of the intermediate portion 33 is positioned closer to the inside of the cylindrical shape 405 than the center of the intermediate portion 33. One end 31 extends from the corresponding first extension 22 toward one end (one end in the circumferential direction) of the intermediate section 33, gradually displacing inward in the radial direction. Similarly, the other end 32 extends from the corresponding first extension 22 toward the other end (the other end in the circumferential direction) of the intermediate section 33, gradually displacing inward in the radial direction. In this way, the entire connecting section 30 is contained within a virtual cylindrical shape 405 that encloses the aggregate of the multiple zigzag extension sections 20 with a minimum diameter.

[0020] In this embodiment, in the zigzag extension portion 20, the radius of curvature of the first vertex 25 and the second vertex 27 is the smallest, and the radius of curvature of the first vertex 25 and the second vertex 27 is equal to, for example, the radius of curvature of the connecting portion 30. Here, "equal" means that the radius of curvature of the connecting portion 30 is at least 0.9 times and the radius of curvature of the first apex 25 (or second apex 27) is at least 1.1 times. Furthermore, in the zigzag extension section 20, the radius of curvature of the first extension section 22 and the second extension section 23 are the largest. More specifically, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10 (Figure 4(b)), the radius of curvature of the intermediate portion 33 is smaller than the radius of curvature of the zigzag extension portion 20. Note that Figure 4(b) shows, as an example, the cross-section of the intermediate portion 33 along the BB line, but in other parts of the connecting portion 30, the radius of curvature is also smaller than that of the zigzag extension portion 20. Furthermore, as shown in Figure 4(c), in the cross-section along the direction perpendicular to the axis of the cylindrical 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 connecting portion 30. Note that Figure 4(c) shows, as an example, the cross-section along the CC line of the first extension portion 22 and the second extension portion 23, but in other parts of the first extension portion 22 and the second extension portion 23, their radii of curvature are also larger than the radius of curvature of the connecting portion 30. Here, "large" means that in the circumferential direction of the cylindrical portion 10, the radius of curvature of the first extended portion 22 (or the second extended portion 23) is at least 1.1 times the radius of curvature of the intermediate portion 33. Furthermore, in the cross-section along a direction perpendicular to the axis of the cylindrical portion 10 (Figure 4(a)), the radius of curvature of the first apex portion 25 is smaller than the radii of curvature of the first extension portion 22 and the second extension portion 23, respectively. Note that Figure 4(a) shows, as an example, a cross-section along line AA of the first apex portion 25, but in other parts of the first apex portion 25 as well, the radius of curvature is smaller than the radii of curvature of the first extension portion 22 and the second extension portion 23, respectively. Similarly, although not shown in the diagram, in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the second apex portion 27 is smaller than the respective radii of curvature of the first extension portion 22 and the second extension portion 23. Furthermore, in a cross-section along a direction perpendicular to the axis of the cylindrical 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 part of the zigzag extension 20 and the connecting part 30 is not limited to the above example, and it is sufficient that, at least in the circumferential direction of the cylindrical part 10, the radius of curvature of the connecting part 30 is smaller than the radius of curvature of the zigzag extension 20.

[0022] 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.

[0023] Here, the stent 100 is, for example, a covered stent comprising a cylindrical resin membrane 50 attached along the stent 100. The resin film 50 is formed to be longer than the cylindrical portion 10 in the axial direction. The tip of the resin film 50 protrudes from the tip side of the cylindrical portion 10, and this protruding portion constitutes the check valve portion 52. The check valve portion 52 allows flow to one side (for example, the proximal end side) in the axial direction of the cylindrical portion 10 within the stent 100, while restricting flow to the opposite side (for example, the tip side). Furthermore, the resin film 50 is provided with a marker portion 54. The marker portion 54 is positioned closer to the tip than the middle (in the axial direction) of the resin film 50 and closer to the proximal end than the end winding portion 40. When implanting the stent 100, the marker portion 54 can be used as a guide to position the tip of the stent 100 relative to the biological lumen (for example, so that the tip of the stent 100 protrudes from the biological lumen by a desired length). In Figure 1, the area where the marker portion 54 is located is represented by a shading of multiple dots. The resin film 50 is composed of a resin material such as silicone rubber. For example, the resin film 50 is formed by impregnating the cylindrical portion 10 with the resin material, and is a cylindrical film of 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 it may be a ring made of metal or resin. In this invention, the stent 100 does not necessarily have to include a resin film 50; for example, it may be a bare stent.

[0024] Furthermore, in this embodiment, the stent 100 has a covering portion that covers the cylindrical portion 10. As described above, in the circumferential direction of the cylindrical portion 10, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extension portion 20, thus suppressing interference of the connecting portion 30 with the covering portion. Furthermore, snagging of the connecting portion 30 with the covering portion when the covering portion is placed over the cylindrical portion 10 is also suppressed, thereby improving the ease of manufacturing the stent 100. In this embodiment, the covering portion is a covering film 60 formed in a cylindrical shape and covering the cylindrical portion 10. The covering film 60 is arranged coaxially with the cylindrical portion 10. Furthermore, the covering film 60 is configured to shrink in diameter as the diameter of the stent 100 shrinks, and to expand in diameter as the diameter of the stent 100 expands. The inner diameter of the covering film 60 and the outer diameter of the cylindrical portion 10 are equal to each other. The materials constituting the coating film 60 are not particularly limited, but examples include silicone rubber, urethane, polyethylene, and polytetrafluoroethylene.

[0025] Furthermore, as shown in Figure 6, the outer circumferential surface of the connecting portion 30 may have a plurality of narrow grooves 29 extending in a direction that includes an axial component. With this configuration, the outer surface of the connecting portion 30 includes irregularities that extend in a direction including an axial component, so that the adhesion of the covering film 60 to the outer surface of the connecting portion 30 can be ensured. The multiple narrow grooves 29 may, for example, extend in the same direction from one another, or they may extend in different directions from one another. Also, the multiple narrow grooves may, for example, be set to the same dimensions from one another, or they may be set to different dimensions from one another. The width dimension of the multiple narrow grooves 29 (dimension in a direction perpendicular to the extension direction) is preferably, for example, 1 μm or more and 150 μm or less, and more preferably 1 μm or more and 100 μm or less. The length of the multiple fine grooves 29 is preferably, for example, 10 μm to 200 μm, and more preferably 50 μm to 150 μm.

[0026] <Example 1> Next, the stent 100 according to modified example 1 will be explained using Figures 8 to 9(c). The stent 100 according to this modified example differs from the stent 100 according to the above embodiment in the respects described below, and is otherwise configured in the same way as the stent 100 according to the above embodiment. Figure 8 shows the stent 100 cut along its axial direction at one point in the circumferential direction and unfolded flat, and the left-right direction in Figure 8 corresponds to the circumferential direction of the stent 100.

[0027] In this modified example, the connecting portion 30 has end-end connecting portions 35 that connect the two ends of the connecting portion 30 in the circumferential direction. The connecting portions 35 at both ends have a straight portion 36 that is linear in shape when viewed in the radial direction, and bent portions 38 that are connected to both ends of the straight portion 36 (one end 36a and the other end 36b). With this configuration, the connecting portion 30 can achieve both appropriate elasticity and shape retention, so that it can maintain the state in which the multiple zigzag extensions 20 are connected while closely following the reduction or expansion of the diameter of the stent 100.

[0028] In this modified example, the intermediate portion 33 constitutes the end-end connecting portion 35. Therefore, the end-end connecting portion 35 connects the base end of one end 31 to the tip of the other end 32. Each of the two ends, 31 and 32, is inclined, for example, in a direction intersecting the axial direction (for example, the downward-sloping direction to the left in Figure 8). The two ends, 31 and 32, are aligned on the same straight line. The straight section 36 is inclined in a direction that intersects with respect to each of the two ends, for example, one end 31 and the other end 32 (for example, the upward-sloping direction in Figure 8). One end 36a of the straight section 36 is connected to the bent section 38a, and the other end 36b of the straight section 36 is connected to the bent section 38b. Furthermore, the bent section 38a is connected to the base end of the one end 31, and the bent section 38b is connected to the tip of the other end 32. The bent portion 38a and the bent portion 38b are, for example, symmetrical in the axial direction with respect to the straight portion 36. More specifically, the boundary between one end 36a of the straight section 36 and the bent section 38a is, for example, a convex arc in the direction including the other component in the circumferential direction (for example, the right side in Figure 8). The boundary between the other end 36b of the straight section 36 and the bent section 38b is, for example, a convex arc in the direction including the other component in the circumferential direction (for example, the left side in Figure 8). The boundary between the base end of one end 31 and the bent portion 38a is convex in the direction including one component of the circumferential direction (for example, diagonally downward to the left in Figure 8). The boundary between the tip of the other end 32 and the bent portion 38b is convex in the direction including the other component of the circumferential direction (for example, diagonally upward to the right in Figure 8).

[0029] As shown in Figure 9(b), in this modified example as well, the connecting portion 30 is housed inside a virtual cylindrical shape 405 that encloses the aggregate of multiple zigzag extensions 20 with the smallest possible diameter. Furthermore, in this modified example as well, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10 (Figure 9(b)), the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extension portion 20.

[0030] In this modified example as well, in the zigzag extension portion 20, the radii of curvature of the first vertex 25 and the second vertex 27 are the smallest, and the radii of curvature of the first vertex 25 and the second vertex 27 are, for example, equal to the radius of curvature of the connecting portion 30. Furthermore, in the zigzag extension section 20, the radius of curvature of the first extension section 22 and the second extension section 23 are the largest. More specifically, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10 (Figure 9(b)), 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 extension portion 20. Note that Figure 9(b) shows, as an example, the cross-section of the intermediate portion 33 along the BB line, but in other parts of the connecting portion 30 as well, the radius of curvature is smaller than the radius of curvature of the zigzag extension portion 20. Furthermore, in the cross-section along the direction perpendicular to the axis of the cylindrical 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 both larger than the radius of curvature of the connecting portion 30. Furthermore, in the cross-section along a direction perpendicular to the axis of the cylindrical portion 10 shown in Figure 9(a) (for example, line AA shown in Figure 8), the radius of curvature of the first apex 25 is smaller than the respective radii of curvature of the first extension 22 and the second extension 23. Similarly, although not shown, in the cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the second apex 27 is smaller than the respective radii of curvature of the first extension 22 and the second extension 23. Furthermore, in a cross-section along a direction perpendicular to the axis of the cylindrical 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] <Modification 2> Next, a modified example 2 of the stent 100 will be explained using Figures 10 to 11(c). The stent 100 according to this modified example differs from the stent 100 according to the above embodiment in the respects described below, and is otherwise configured in the same way as the stent 100 according to the above embodiment. Figure 10 shows the stent 100 cut along its axial direction at one point in the circumferential direction and laid flat, and the left-right direction in Figure 10 corresponds to the circumferential direction of the stent 100.

[0032] In this modified example, the connecting portion 30 connects the adjacent vertices of a plurality of zigzag extensions 20 to each other. More specifically, the connecting portion 30 connects the first vertex 25 of one zigzag extension 20 to the second vertex 27 of another zigzag extension 20 that is axially opposite to the first vertex 25. In this modified example as well, in the circumferential direction of the cylindrical portion 10, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the annular zigzag extension portion 20. With this configuration, it is possible to prevent the circumferential ends of the connecting portion 30 from getting caught on the inner wall surface of the biological lumen 300 or the like. Furthermore, as the connecting portion 30 expands and contracts with the expansion of the stent 100, the connecting portion 30 is less likely to come into contact with the inner wall surface of the biological lumen 300, thus ensuring the expandability and flexibility of the stent 100. Therefore, the stent 100 can be placed in a desired location within the biological lumen 300 with minimal invasiveness. The present invention is not limited to this example, and the connecting portion 30 may, for example, connect the first apex 25 of one zigzag extension portion 20 to the first apex 25 of another zigzag extension portion 20 that is facing the first apex 25 in the axial direction, or it may connect the second apex 27 of one zigzag extension portion 20 to the second apex 27 of another zigzag extension portion 20 that is facing the second apex 27 in the axial direction.

[0033] As shown in Figure 11(b), in this modified example as well, the connecting portion 30 is housed inside a virtual cylindrical shape 405 that encloses the aggregate of multiple zigzag extensions 20 with the smallest possible diameter. Furthermore, in this modified example, as shown in Figures 10 and 11(b), in the circumferential direction of the cylindrical portion 10, each of the two ends of the connecting portion 30 (one end 30a and the other end 30b) is positioned closer to the inside of the cylindrical shape 405 than the central portion 30c of the connecting portion 30. In Figure 11(b), for convenience, the cross-sections of each of the two ends of the connecting portion 30 (in this modified example, both ends of the connecting portion 35) in the circumferential direction of the cylindrical portion 10 (cross-sections along a direction perpendicular to the axis of the cylindrical portion 10) are shown with dashed lines. With this configuration, it is possible to more reliably prevent both ends of the connecting portion 30 in the circumferential direction (one end 30a and the other end 30b) from getting caught on the inner wall surface of the biological lumen 300 or the like. In this context, "positioned towards the inside" means that at least the outer circumferential surfaces of one end 30a and the other end 30b of the connecting portion 30 are positioned closer to the inside (radially inward) of the cylindrical shape 405 than the outer circumferential surface of the central portion 30c.

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

[0035] Furthermore, in this modified example, as shown in Figures 11(a) and 11(b), in the circumferential direction of the cylindrical portion 10, the radii of curvature of the adjacent vertices of the zigzag extension portion 20 and the radii of curvature of the connecting portions 35 at both ends are equal to each other. In this context, "the adjacent vertices of the zigzag extension 20" refers to the vertices of the zigzag extension 20 that are connected to each other by the connecting portion 30. In this modified example, these are the first vertex 25 and the second vertex 27 that are connected to each other via the connecting portion 30. Furthermore, "equal" here means that the radii of curvature of the adjacent vertices of the zigzag extension 20 are between 0.9 and 1.1 times the radii of curvature of the connecting portions 35 at both ends. With this configuration, there are no points of change in the radius of curvature at or near the connection point 30, and when the stent 100 shrinks or expands in diameter, the stress can be evenly distributed at or near the connection point 30. Therefore, the shape of the connection point 30 and its vicinity can be maintained in good condition (unintended deformation can be suppressed).

[0036] More specifically, as shown in Figure 10, in this modified example, at the connecting portion 30, one end 31 is connected to the first apex 25, and the other end 32 is connected to the second apex 27. In this modified example, the intermediate portion 33 constitutes the end-end connecting portion 35. Therefore, the end-end connecting portion 35 connects the base end of one end 31 to the tip of the other end 32. The intermediate portion 33 is formed, for example, in a straight line and is inclined in a direction intersecting the axial direction (for example, the upward-sloping direction in Figure 10). Each of the two ends, 31 and 32, is formed in a straight line and is inclined in a direction that intersects the intermediate portion 33 (for example, the upward-sloping direction to the left in Figure 10). The boundary between one end 31 and the intermediate part 33 is, for example, a convex arc in the direction including the other component in the circumferential direction (for example, the right side in Figure 10). The boundary between the other end 32 and the intermediate part 33 is, for example, a convex arc in the direction including the other component in the circumferential direction (for example, the left side in Figure 8). The length of one end 31 and the other end 32 are, for example, smaller than the length of the intermediate section 33. As shown in Figure 11(b), in the circumferential direction of the cylindrical portion 10, each of the two ends (one end 36a, 36b) of the two-end connecting portion 35 is positioned closer to the inside of the cylindrical shape 405 than the central portion 30c of the connecting portion 30. More specifically, the boundary between one end 36a of the double-ended connecting portion 35 and the base end of the one end 31 protrudes to one side in the circumferential direction (for example, to the right in Figure 10) beyond the corresponding second apex 27, and constitutes one end 30a of the circumferential connecting portion 30. Similarly, the boundary between the other end 36b of the double-ended connecting portion 35 and the tip of the other end 32 protrudes to the other side in the circumferential direction (for example, to the left in Figure 10) beyond the corresponding first apex 25, and constitutes the other end 30b of the circumferential connecting portion 30. In this modified example, when viewed in the axial direction, the entire connecting portion 30 has a convex arc shape directed radially outward.

[0037] In this modified example as well, in the zigzag extension portion 20, the radii of curvature of the first vertex 25 and the second vertex 27 are the smallest, and the radii of curvature of the first vertex 25 and the second vertex 27 are, for example, equal to the radius of curvature of the connecting portion 30. Furthermore, in the zigzag extension section 20, the radius of curvature of the first extension section 22 and the second extension section 23 are the largest. More specifically, in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10 (see Figure 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 Figure 11(b) shows, as an example, a cross-section along the BB line of the straight portion 36, but in other parts of the connecting portion 30 as well, the radius of curvature of the outer surface is smaller than the radius of curvature of the annular zigzag extension portion 20. Furthermore, in the cross-section along the direction perpendicular to the axis of the cylindrical 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 connecting portion 30. Furthermore, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10 shown in Figure 11(a), the radius of curvature of the first apex 25 is smaller than the radii of curvature of the first extension 22 and the second extension 23, respectively. Similarly, although not shown, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the second apex 27 is smaller than the radii of curvature of the first extension 22 and the second extension 23, respectively. Furthermore, in the cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature 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.

[0038] <Variation 3> Next, the stent 100 according to modified example 3 will be explained using Figures 12 to 13(c). The stent 100 according to this modified example differs from the stent 100 according to Modified Example 2 described above in the respects described below, and is otherwise configured in the same way as the stent 100 according to Modified Example 2 described above. Figure 12 shows the stent 100 cut along its axial direction at one point in the circumferential direction and unfolded flat, and the left-right direction in Figure 12 corresponds to the circumferential direction of the stent 100.

[0039] In this modified example, as in Modification Example 2, the connecting 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 is axially opposite to the first apex 25. However, in this modified example, the entire connecting portion 30 is bent, and its radial shape is roughly S-shaped. As shown in Figure 12, one end 31 of the connecting portion 30 extends from the first apex 25 in a direction that includes a component in the opposite direction (upward in Figure 12) to the protruding direction of the second apex 27 (downward in Figure 12) (upward in Figure 12), and the other end 32 of the connecting portion 30 extends from the second apex 27 in a direction that includes a component in the opposite direction (downward in Figure 12) to the protruding direction of the first apex 25 (upward in Figure 12) (downward in Figure 12). With this configuration, when the stent 100 is in its expanded diameter state, the relative axial displacement between adjacent zigzag extensions 20 is appropriately restricted by the connecting portion 30, making it possible to more reliably maintain the axial length dimension of the stent 100 at the intended dimension.

[0040] More specifically, the connecting portion 30 includes, for example, a first portion 39a which is convex to one side in the circumferential direction (for example, to the left in Figure 12), and a second portion 39b which is convex to the other side in the circumferential direction (for example, to the right in Figure 12). One end of the first part 39a is connected to the first apex 25, and the other end of the first part 39a is connected to one end of the second part 39b. The other end of the second part 39b is connected to the second apex 27. In this modified example, one end 31 of the connecting part 30 is made up of one end of the first part 39a, and the other end 32 of the connecting part 30 is made up of the other end of the second part 39b. The intermediate part 33 of the connecting part 30 is made up of the boundary between the first part 39a and the second part 39b. The first part 39a and the second part 39b are formed to be the same shape as each other and are arranged symmetrically in the circumferential direction. The radius of curvature of each of the first part 39a and the second part 39b (the radius of curvature of the arc-shaped portion) is greater than, for example, the radius of curvature of each of the first vertex 25 and the second vertex 27 (the radius of curvature of the arc-shaped portion). In this modified example, when the cylindrical portion 10 is viewed in the axial direction, the entire connecting portion 30 has a convex arc shape that extends radially outward. Furthermore, the entire connecting portion 30 is housed inside the cylindrical shape 405.

[0041] As shown in Figure 13(b), in this modified example as well, the connecting portion 30 is housed inside a virtual cylindrical shape 405 that encloses the aggregate of multiple zigzag extensions 20 with the smallest diameter. In the circumferential direction of the cylindrical portion 10, each of the two ends of the connecting portion 30 (one end 30a, the other end 30b) is positioned closer to the inside of the cylindrical shape than the central portion 30c of the connecting portion 30. In Figure 13(b), for convenience, the cross-sectional surfaces of each end of the connecting portion 30 (cross-sectional surfaces along the direction perpendicular to the axis of the cylindrical portion 10) are shown with dashed lines.

[0042] In this modified example as well, in the zigzag extension portion 20, the radii of curvature of the first vertex 25 and the second vertex 27 are the smallest, and the radii of curvature of the first vertex 25 and the second vertex 27 are, for example, equal to the radius of curvature of the connecting portion 30. Furthermore, in the zigzag extension section 20, the radius of curvature of the first extension section 22 and the second extension section 23 are the largest. More specifically, as shown in Figure 13(b), in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10, 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 Figure 13(b) shows, as an example, a cross-section along the BB line of the intermediate portion 33, but in other parts of the connecting portion 30 as well, the radius of curvature of the outer surface is smaller than the radius of curvature of the annular zigzag extension portion 20. Furthermore, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10 shown in Figure 13(a), the radius of curvature of the first apex 25 is smaller than the radii of curvature of the first extension 22 and the second extension 23, respectively. Similarly, although not shown, in the cross-section along the direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the second apex 27 is smaller than the radii of curvature of the first extension 22 and the second extension 23, respectively. Furthermore, in the cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature 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. Furthermore, in the cross-section along the direction perpendicular to the axis of the cylindrical 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 connecting portion 30.

[0043] Furthermore, in this modified example as well, in the circumferential direction, the dimension of the connecting portion 30 (L2 shown in Figure 12) is greater than the distance between adjacent vertices of the zigzag extension portion 20 connected via the connecting portion 30 (L1 shown in Figure 12).

[0044] <Modification 4> Next, a modified example of the embodiment 4, the stent 100, will be described using Figure 14. The stent 100 according to this modified example differs from the stent 100 according to Modified Example 3 described below in the respects described below, and is otherwise configured in the same way as the stent 100 according to Modified Example 3. Figure 12 shows the stent 100 cut along its axial direction at one point in the circumferential direction and unfolded flat, and the vertical direction in Figure 12 corresponds to the circumferential direction of the stent 100.

[0045] In this modified example, as in Modified Example 3, the entire connecting portion 30 is bent, and its shape when viewed in the radial direction is roughly S-shaped. However, in this modified example, the connecting portion 30 connects the first extending portion 22 of one zigzag extending portion 20 to the second extending portion 23 of another zigzag extending portion 20 that is adjacent to the first extending portion 22. Furthermore, the radius of curvature of the first part 39a is larger than that of the first part 39a in modified example 3, and the radius of curvature of the second part 39b is larger than that of the second part 39b in modified example 3. In this modified example as well, when the stent 100 expands in diameter, the relative axial displacement between adjacent zigzag extensions 20 is appropriately restricted by the connecting portion 30, ensuring that the stent 100 extends more reliably with the intended displacement.

[0046] <Modification 5> Next, a modified example of the embodiment 5, the stent 100, will be described using Figures 15 to 16(c). The stent 100 according to this modified example differs from the stent 100 according to the above embodiment and modified examples 1 to 4 in the respects described below, and is otherwise configured the same as the stent 100 according to the above embodiment and modified examples 1 to 4. Figure 15 shows the stent 100 cut along its axial direction at one point in the circumferential direction and unfolded flat, and the left-right direction in Figure 15 corresponds to the circumferential direction of the stent 100.

[0047] In this modified example, the connecting portion 30 connects the second extending portion 23 of one zigzag extending portion 20 to the second extending portion 23 of another zigzag extending portion 20 that is adjacent to the said second extending portion 23, similar to the embodiments and modified examples 1 and 4 described above. However, the entire intermediate portion 33 is bent, as in the connecting portion 30 of modified example 3, and its radial shape is roughly an S-shape arranged diagonally.

[0048] The intermediate portion 33 includes, for example, a first portion 39a which is convex towards one side in the circumferential direction (for example, the left side in Figure 15), and a second portion 39b which is convex towards the other side in the circumferential direction (for example, the right side in Figure 15). The first part 39a and the second part 39b are formed to be the same shape as each other and are arranged symmetrically in the circumferential direction. The radius of curvature of each of the first part 39a and the second part 39b (the radius of curvature of the arc-shaped portion) is greater than, for example, the radius of curvature of each of the first vertex 25 and the second vertex 27 (the radius of curvature of the arc-shaped portion). Each of the two ends, 31 and 32, extends in a straight line and is inclined in a direction intersecting the axial direction (for example, the upward-sloping direction in Figure 15).

[0049] In this modified example as well, the connecting portion 30 is housed inside a virtual cylindrical shape 405 that encloses the aggregate of multiple zigzag extensions 20 with the smallest possible diameter.

[0050] In this modified example as well, in the zigzag extension portion 20, the radii of curvature of the first vertex 25 and the second vertex 27 are the smallest, and the radii of curvature of the first vertex 25 and the second vertex 27 are, for example, equal to the radius of curvature of the connecting portion 30. Furthermore, in the zigzag extension section 20, the radius of curvature of the first extension section 22 and the second extension section 23 are the largest. More specifically, as shown in Figure 16(b), in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the connecting portion 30 is smaller than the radius of curvature of the zigzag extension portion 20. Note that Figure 16(b) shows, as an example, a cross-section along the BB line of the intermediate portion 33, but in other parts of the connecting portion 30 as well, the radius of curvature of the outer surface is smaller than the radius of curvature of the annular zigzag extension portion 20. Furthermore, as shown in Figure 16(c), in the cross-section along the direction perpendicular to the axis of the cylindrical 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 connecting portion 30. Furthermore, as shown in Figure 16(a), in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the first apex 25 is smaller than the radii of curvature of the first extension 22 and the second extension 23, respectively. Similarly, although not shown, in a cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature of the second apex 27 is smaller than the radii of curvature of the first extension 22 and the second extension 23, respectively. Furthermore, in the cross-section along a direction perpendicular to the axis of the cylindrical portion 10, the radius of curvature 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.

[0051] Although embodiments and various modifications 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 and various modifications, but also includes various forms of modification, improvement, etc., as long as the objective of the present invention is achieved.

[0052] 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.

[0053] This embodiment encompasses the following technical concepts. (1) A stent having a cylindrical portion, The aforementioned cylindrical portion is The cylindrical portion has multiple annular zigzag extensions that extend circumferentially while oscillating in a zigzag pattern in the axial direction, and these are arranged in a manner that is offset from each other in the axial direction. It has connecting parts that connect adjacent zigzag extensions in the axial direction, A stent in which, 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 extension portion. (2) The stent according to (1), wherein the connecting portion is housed inside a virtual cylindrical shape that encloses the collection of the plurality of zigzag extensions with the minimum diameter. (3) The stent according to (2), wherein in the circumferential direction of the cylindrical portion, each of the two ends of the connecting portion is positioned closer to the inside of the cylindrical shape than the central portion of the connecting portion. (4) The connecting portion has connecting portions at both ends that connect the two ends of the connecting portion in the circumferential direction, The aforementioned connecting portions at both ends are, The shape when viewed in the radial direction is a straight line, The curved sections are connected to both ends of the aforementioned straight section, A stent according to any one of (1) to (3) having the following characteristics. (5) The stent according to (4), wherein in the circumferential direction of the cylindrical portion, the radii of curvature of the adjacent vertices of the zigzag extension and the radii of curvature of the connecting portions at both ends are equal to each other. (6) The stent according to any one of (1) to (5), wherein in the circumferential direction, the dimensions of the connection portion are greater than the distance between the adjacent vertices of the zigzag extension portion connected via the connection portion. (7) A stent according to any one of (1) to (6), having a covering portion that covers the cylindrical 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 part 30a one end 30b Other end 30c central part 31 One end 32 Other end 33 Middle section 35 Connection section at both ends 36 Straight section 36a one end 36b Other end 38. Bending section 39a Part 1 39b Part 2 40 End winding section 42 Yamabe 44 Tanibe 46 Strut section 50 Resin film 52 Check valve section 54 Marker section 60. Covering film (covering part) 100 Stents (Covered Stents) 300 Living lumen 401, 402 Arrangement area of ​​the zigzag extension 405 Virtual cylindrical shape

Claims

1. A stent having a cylindrical portion, The aforementioned cylindrical portion is The cylindrical portion has multiple annular zigzag extensions that extend circumferentially while oscillating in a zigzag pattern in the axial direction, and these are arranged in a manner that is offset from each other in the axial direction. It has connecting parts that connect adjacent zigzag extensions in the axial direction, A stent in which, 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 extension portion.

2. The stent according to claim 1, wherein the connecting portion is housed inside a virtual cylindrical shape that encloses the aggregate of the plurality of zigzag extensions with the minimum diameter.

3. The stent according to claim 2, wherein in the circumferential direction of the cylindrical portion, each of the two ends of the connecting portion is positioned closer to the inside of the cylindrical shape than the central portion of the connecting portion.

4. The aforementioned connecting portion has connecting portions at both ends that connect the two ends of the connecting portion in the circumferential direction, The aforementioned connecting portions at both ends are, The shape when viewed in the radial direction is a straight line, The curved sections are connected to both ends of the aforementioned straight section, A stent according to any one of claims 1 to 3.

5. The stent according to claim 4, wherein, in the circumferential direction of the cylindrical portion, the radii of curvature of the adjacent vertices of the zigzag extension and the radii of curvature of the connecting portions at both ends are equal to each other.

6. The stent according to any one of claims 1 to 3, wherein the dimensions of the connection portion are greater than the distance between the adjacent vertices of the zigzag extension portion connected via the connection portion in the circumferential direction.

7. A stent according to any one of claims 1 to 3, having a covering portion that covers the tubular portion.

Images