stent

Abstract

The present invention provides a stent capable of suppressing unintended shape changes of the stent after its placement. [Solution] The stent 100 has a cylindrical portion 10, the cylindrical portion 10 has a plurality of zigzag extensions 20 and connecting portions 30 that connect adjacent zigzag extensions 20 in the axial direction, and when the load-applying member 110 is moved from one side to the other, a load is applied to the stent 100 that compresses the stent 100 in the radial direction, and the rebound force of the stent 100 at that time is measured, the ratio of the first rebound force F1 to the second rebound force F2 is taken as the first ratio, and the ratio of the third rebound force F3 to the fourth rebound force F4 is taken as the second ratio, then one of the first ratio and the second ratio will be greater than 100%, and the other will be less than 100%.

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.

Prior Art Documents

Patent Documents

[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, the stent of Patent Document 1 has room for improvement from the viewpoint of suppressing an unintended shape change of the stent after the stent is placed.

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 zigzag extending portions that extend in the circumferential direction while zigzagging in the axial direction of the cylindrical portion, and the plurality of zigzag extending portions are arranged so as to be displaced from each other in the axial direction, and has connecting portions that connect the adjacent zigzag extending portions in the axial direction, the stent has a coating film that covers the cylindrical portion, [[ID=5十二]]Regarding the result of measuring the repulsive force of the stent when a load applying member is moved from one side to the other side to apply a load that compresses the stent in the radial direction to the stent, With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent, the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the first repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned at one end of the stent from which the coating film has been removed, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the second repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from one end of the stent, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the third repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from the one end of the stent from which the coating film has been removed, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the fourth repulsive force. The ratio of the first rebound force to the second rebound force is defined as the first ratio. If the ratio of the third rebound force to the fourth rebound force is taken as the second ratio, A stent is provided in which one of the first ratio and the second ratio exceeds 100%, and the other falls below 100%. [Effects of the Invention]

[0006] According to the present invention, unintended changes in the shape of the stent can be suppressed after the stent has been placed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic plan view of the stent according to the first embodiment. [Figure 2] This is a schematic plan view of the stent according to the first embodiment, showing the state after the coating film has been removed. [Figure 3]Figure 3(a) is a schematic diagram illustrating the first repulsive force, and Figure 3(b) is a schematic diagram illustrating the second repulsive force. [Figure 4] Figure 4(a) is a schematic diagram illustrating the third repulsive force, and Figure 4(b) is a schematic diagram illustrating the fourth repulsive force. [Figure 5] Figure 5(a) is a schematic diagram illustrating the fifth repulsive force, and Figure 5(b) is a schematic diagram illustrating the sixth repulsive force. [Figure 6] This is a schematic cross-sectional view of the stent according to the first embodiment. [Modes for carrying out the invention]

[0008] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. 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. Also, in Figure 1, the shapes of the multiple zigzag extensions 20 are shown in a simplified manner. Figure 6 shows a cross-section of the stent 100 along a direction perpendicular to the axis of the cylindrical portion 10.

[0009] [First Embodiment] First, the first embodiment will be described using Figures 1 to 6. The stent 100 according to this embodiment has a cylindrical portion 10. As shown in Figure 1, the cylindrical portion 10 has a plurality of zigzag extension portions 20 that extend circumferentially while oscillating in a zigzag pattern in the axial direction of the cylindrical portion 10, arranged in a staggered manner in the axial direction, and also has connecting portions 30 that connect adjacent zigzag extension portions 20 in the axial direction. The stent 100 has a covering film (in this embodiment, a first covering film 66 and a second covering film 68) that covers the cylindrical portion 10. The load-applying member 110 was moved from one side to the other (from one side to the other in the radial direction of the stent 100), and a load was applied to the stent 100 to compress it radially. The results of measuring the rebound force of the stent 100 at that time are described below. With the rotation angle of the stent 100 adjusted around its axis so that the connection portion 30 is positioned at one end 100a of the stent 100, the repulsive force when a load is applied to the location of the connection portion 30 on the stent 100 is defined as the first repulsive force F1 (see Figure 3(a)). With the rotation angle of the stent 100 adjusted around its axis so that the connecting portion 30 is positioned at one end 100a of the stent 100 from which the coating film has been removed, the repulsive force when a load is applied to the location of the connecting portion 30 on the stent 100 is defined as the second repulsive force F2 (see Figure 3(b)). With the rotation angle of the stent 100 adjusted around its axis so that the connection portion 30 is positioned away from one end 100a of the stent 100, the repulsive force when a load is applied to the location of the connection portion 30 on the stent 100 is defined as the third repulsive force F3 (see Figure 4(a)). With the rotation angle of the stent 100 adjusted around its axis so that the connection portion 30 is positioned away from one end 100a of the stent 100 from which the coating film has been removed, the repulsive force when a load is applied to the location of the connection portion 30 on the stent 100 is defined as the fourth repulsive force F4 (see Figure 4(b)). If we define the ratio of the first rebound force F1 to the second rebound force F2 as the first ratio, and the ratio of the third rebound force F3 to the fourth rebound force F4 as the second ratio, then one of the first and second ratios will exceed 100%, and the other will fall below 100%. Here, the "arrangement offset from each other in the axial direction" means that in the expanded diameter state of the stent 100, the arrangement region of one zigzag extending portion 20 and the arrangement region of another zigzag extending portion 20 adjacent to the zigzag extending portion 20 may overlap each other or may not overlap each other in the axial direction. However, when the arrangement region of one zigzag extending portion 20 and the arrangement region 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 intersect each other. In the present invention, the moving direction (load direction) of the load applying member 110 is a linear direction. Also, the "one end 100a" is the end on the opposite side to the load direction of the load applying member 110. In addition, the coating film covering the cylindrical portion 10 includes a film covering the outer peripheral side of the cylindrical portion 10, a film covering the inner peripheral side of the cylindrical portion 10, and a film of the same layer as the cylindrical portion 10. Also, when adjacent zigzag extending portions 20 in the axial direction are connected to each other by connection portions 30 at a plurality of positions in the circumferential direction, the "state where the rotational angle of the stent 100 around the axis is adjusted so that the connection portion 30 is arranged at one end 100a" means that any one of the plurality of connection portions 30 in the circumferential direction is arranged at one end 100a. Also, the "state where the rotational angle of the stent 100 around the axis is adjusted so that the connection portion 30 is arranged at a position avoiding one end 100a" means that all of the plurality of connection portions 30 are arranged at positions avoiding one end 100a. Further, among the plurality of connection portions 30, the midpoint (midpoint in the circumferential direction) between any two adjacent connection portions 30 in the circumferential direction is arranged at one end 100a. Furthermore, in the present invention, for at least one of the plurality of connection portions 30 in the circumferential direction, it is sufficient to satisfy the condition that one of the first ratio and the second ratio exceeds 100% and the other is less than 100%. More preferably, all of the connection portions 30 in the circumferential direction satisfy this condition. Similarly, in the present invention, for at least one of the plurality of connection portions 30 in the axial direction, it is only necessary to satisfy the condition that one of the first ratio and the second ratio exceeds 100% and the other is less than 100%. More preferably, all the connection portions 30 in the axial direction satisfy this condition.

[0010] Note that FIGS. 3(a) and 4(a) are cross-sectional views taken along the line A-A shown in FIG. 1, and FIG. 5(a) is a cross-sectional view taken along the line B-B shown in FIG. 1. In FIG. 3(a), the stent 100 is in a state where the rotational angle of the stent 100 around the axis is adjusted so that the connection portion 30 is disposed at one end 100a (the upper end in FIG. 3(a)) on one side. In FIG. 4(a), the stent 100 is in a state where the rotational angle of the stent 100 around the axis is adjusted so that the connection portion 30 is disposed at a position avoiding one end 100a. Also, FIGS. 3(b) and 4(b) are cross-sectional views taken along the line A-A shown in FIG. 2, and FIG. 5(b) is a cross-sectional view taken along the line B-B shown in FIG. 2. In FIG. 3(b), the stent 100 is in a state where the rotational angle of the stent 100 around the axis is adjusted so that the connection portion 30 is disposed at one end 100a (the upper end in FIG. 3(b)) on one side. In FIG. 4(b), the stent 100 is in a state where the rotational angle of the stent 100 around the axis is adjusted so that the connection portion 30 is disposed at a position avoiding one end 100a. Also, in FIGS. 2, 3(b), 4(b), and 5(b), the coating films (the first coating film 66 and the second coating film 68) are illustrated by a two-dot chain line.

[0011] 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 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. The contracted state of stent 100 refers to a state in which stent 100 is compressed radially to the extent that it can exist within the outer sheath. The expanded state of stent 100 refers to a state in which it is at least expanded compared to the contracted state, for example, the natural state of stent 100. In Figures 1 to 6, stent 100 is shown in the expanded state (natural state).

[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] In the present invention, the "results of measuring the rebound force of the stent 100" refers to the rebound force (radial force (radial elastic restoring force)) of the stent 100 when a load compressing it radially is applied to the stent 100 in its natural state (expanded state). In this embodiment, as an example, the rebound force of the stent 100 is a value measured using a tensile-compression testing machine (AGS-5kNX, manufactured by Shimadzu Corporation, load cell: AGS-X·EZ-X 50N). More specifically, first, the stent 100 is placed on the horizontal plate 120. Next, the end face 110a of the load-applying member 110 (for example, a flat plate member with a thickness of 1 mm) is placed on one end of the stent 100 in the radial direction. At this time, the end face 110a of the load-applying member 110 is positioned parallel to the horizontal plate 120. Furthermore, the width dimensions of the load-applying member 110 and the horizontal plate 120 are larger than the outer diameter of the stent 100, and the entire radial portion of the stent 100 is contained within the respective widths of the load-applying member 110 and the horizontal plate 120. Also, the entire axial portion of the stent 100 is positioned on the horizontal plate 120. Next, the load-applying member 110 is moved radially, and the rebound force is measured while the stent 100 is compressed to 50% of its natural outer diameter. In this manner, the first rebound force F1 to the fourth rebound force F4, as well as the fifth rebound force F5 and sixth rebound force F6 described later, are measured.

[0014] In the stent 100 according to this embodiment, if the ratio of the first rebound force F1 to the second rebound force F2 is defined as the first ratio, and the ratio of the third rebound force F3 to the fourth rebound force F4 is defined as the second ratio, then one of the first ratio and the second ratio will exceed 100%, and the other will fall below 100%. In other words, with respect to the repulsive force at the location where the connection portion 30 is located in the stent 100, the relationship between the magnitude of the repulsive force with and without the coating film is reversed when the rotation angle of the stent 100 around the axis is adjusted so that the connection portion 30 is located at one end 100a, and when the rotation angle of the stent 100 around the axis is adjusted so that the connection portion 30 is located in a position that avoids the one end 100a. With this configuration, even if the coating film partially peels off unintentionally at the location where the connection portion 30 of the stent 100 is positioned, the repulsive force (radial force) at that location can be maintained at the same level as when the coating film is present (the repulsive force when the connection portion 30 is positioned at one end 100a (second repulsive force F2) and the repulsive force when the connection portion 30 is positioned away from the one end 100a (fourth repulsive force F4) are complementary). Therefore, unintended changes in the shape of the stent 100 can be suppressed after its placement. More specifically, even if the coating is partially peeled off, the repulsive force in the entire circumferential direction can be maintained at least at the locations where the connection portion 30 is located in the axial direction, and consequently, the cross-sectional area (area of ​​the cross section along the radial direction) of the stent 100 can be maintained at the same level as the cross-sectional area when the coating is present. Furthermore, if multiple connection parts 30 are arranged in the axial direction, the repulsive force can be maintained throughout the circumferential direction at multiple locations where these connection parts 30 are located.

[0015] The cylindrical portion 10, which includes multiple zigzag extensions 20 and connecting portions 30, can be formed, for example, by cutting (for example, laser cutting) a single pipe (for example, a pipe made of a metal or plastic material). The cross-sectional shape of the wire 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. The outer and inner diameters of the cylindrical portion 10 are substantially constant regardless of their position in the axial direction. However, the present invention is not limited to this example, and the outer diameter and inner diameter of a part of the cylindrical portion 10 may be larger or smaller than those of the other parts.

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

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

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

[0019] Here, as described above, adjacent zigzag extensions 20 in the axial direction are connected by connecting parts 30. More specifically, in this embodiment, connection portions 30 are arranged at one or more locations in the axial direction of the stent 100, and at multiple locations in the circumferential direction. With this configuration, even if the coating film is partially peeled off, the repulsive force in the circumferential direction can be maintained at one or more locations in the axial direction, and consequently, the cross-sectional area (area of ​​the cross section along the radial direction) of the stent 100 can be maintained at the same level as the cross-sectional area when the coating film is present.

[0020] Furthermore, in this embodiment, connection portions 30 are arranged at multiple locations in the axial direction of the stent 100. With this configuration, the repulsive force can be maintained at multiple locations in the axial direction of the stent 100, and consequently, the repulsive force can be maintained throughout the circumferential direction of the stent 100. Furthermore, if connection portions 30 are arranged at multiple locations in the axial direction of the stent 100, it is sufficient that at least one of these locations is configured such that one of the first ratio and the second ratio exceeds 100% and the other is less than 100%. Preferably, at all locations where connection portions 30 are arranged in the axial direction, one of the first ratio and the second ratio exceeds 100% and the other is less than 100%. Furthermore, as will be described later, in some of the multiple locations where the axial connection portion 30 is located, the first ratio may be greater than 100% and the second ratio may be less than 100%, while in the remaining locations, the second ratio may be greater than 100% and the first ratio may be less than 100%.

[0021] More specifically, in this embodiment, in the cylindrical portion 10, one zigzag extension portion 20 and another zigzag extension portion 20 adjacent to the said zigzag extension portion 20 are connected to each other by a plurality (for example, three) of connecting portions 30. As shown in Figure 3(a), the multiple connecting parts 30 that connect adjacent zigzag extensions 20 are positioned offset from each other in the radial direction with respect to the center of the cylindrical part 10. Furthermore, each connecting part 30 is formed to be the same shape as the others and is arranged rotationally symmetrically with respect to the center of the cylindrical part 10. Each connecting part 30 is arranged at equal angular intervals in the circumferential direction. Furthermore, adjacent connection portions 30 in the axial direction are positioned at different locations in the circumferential direction via the corresponding zigzag extension portion 20. In this way, each of the multiple zigzag extensions 20 included in the cylindrical portion 10 (from the zigzag extension 20 located at the tip to the zigzag extension 20 located at the base) is connected to one another by multiple (for example, three) connecting portions 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.

[0022] 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 extension portion 23 of one zigzag extension portion 20 to a second extension portion 23 of another zigzag extension portion 20 that is axially opposite to the second extension portion 23 of the first extension portion 23 of the first zigzag extension portion 20 to each other, or it may connect a first extension portion 22 of one zigzag extension portion 20 to a second extension portion 23 of another zigzag extension portion 20 that is adjacent to the first extension portion 22 of the first extension portion 22 of the first extension portion 22 of the first extension portion 22 of the first zigzag extension portion 20 to each other.

[0023] 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 (intermediate portion in the extending direction) of the connecting portion 30 extends linearly in a direction intersecting each of the one end portion 31 and the other end portion 32. 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. 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.

[0024] 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.

[0025] As shown in Figure 3(a), etc., in this embodiment, the coating film has a two-layer structure (first coating film 66 and second coating film 68). As a result, the first coating film 66 and the second coating film 68 can evenly distribute the load across the entire circumferential direction of the stent 100. Therefore, the expansion force of the stent 100 can be ensured effectively. More specifically, the stent 100 has a first coating film 66, which is a cylindrical film in the same layer as the cylindrical portion 10, and a second coating film 68, which is a cylindrical member that is externally mounted on the cylindrical portion 10. The first coating film 66 is formed to be longer than the cylindrical portion 10 in the axial direction. The tip of the first coating film 66 protrudes from the tip side of the cylindrical portion 10, and the base end of the first coating film 66 protrudes from the base end side of the cylindrical portion 10. The first coating film 66 is made of a resin material such as silicone rubber. For example, the first coating film 66 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 second coating film 68 is formed in a cylindrical shape, and the inner diameter of each of the multiple second coating films 68 and the outer diameter of the cylindrical portion 10 are approximately equal to each other. Furthermore, in the axial direction, the second coating film 68 is set to approximately the same dimensions as the first coating film 66, and the second coating film 68 covers the first coating film 66 from the tip to the base. The material constituting the second coating film 68 is not particularly limited, but examples include silicone rubber, urethane, polyethylene, and polytetrafluoroethylene. However, the present invention is not limited to this example, and the coating film may have a single-layer structure.

[0026] In this embodiment, in the stent 100, the first ratio is greater than 100%, and the second ratio is less than 100%. That is, F1 / F2 > 1 and F3 / F4 < 1. Even with this configuration, as described above, if the coating film partially peels off unintentionally at the location where the connection portion 30 of the stent 100 is positioned, the repulsive force (radial force) at that location will be complementary between the second repulsive force F2 and the fourth repulsive force F4. Therefore, unintended changes in the shape of the stent 100 can be suppressed after its placement. More specifically, the first rebound force F1 is preferably, for example, 1.01 times or more and 2 times or less the second rebound force F2, and more preferably 1.02 times or more and 2 times or less the second rebound force F2. Similarly, the fourth rebound force F4 is preferably, for example, 1.05 times or more and 2 times or less the third rebound force F3, and more preferably 1.06 times or more and 2 times or less the third rebound force F3.

[0027] One method for creating a configuration in which the first ratio exceeds 100% and the second ratio falls below 100% is to make the non-placement area 67a (see Figure 6) of the connecting portion 30 in the coating film (e.g., the first coating film 66) thicker than the placement area 67b (see Figure 6) of the connecting portion 30 in the coating film (e.g., the first coating film 66). Here, the non-placement area 67a of the connecting portion 30 in the coating film refers to the non-placement area 67a of the connecting portion 30 in both the axial and circumferential directions. Similarly, the placement area 67b of the connecting portion 30 in the coating film refers to the placement area 67b of the connecting portion 30 in both the axial and circumferential directions. This makes it possible to achieve a configuration in stent 100 where the first proportion exceeds 100% and the second proportion falls below 100%. More specifically, in the third repulsive force F3, when the connection portion 30 is positioned to avoid one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the non-placement area 67a (thick-walled portion)), stress concentrates at the contact point with the load-applying member 110 in the coating film (the non-placement area 67a (thick-walled portion)). Therefore, the coating film is compressed radially and easily bends in a direction intersecting the axial direction, starting from the non-placement area 67a (thick-walled portion). More specifically, when viewed in a direction perpendicular to the load direction and radially (for example, the left-right direction in Figure 4(a)), the entire coating film bends in a roughly V-shape starting from the contact point with the load-applying member 110 (the non-placement area 67a (thick-walled portion)). Furthermore, each connection portion 30 also bends in a direction intersecting the axial direction, following the bending of the coating film in this manner, so each connection portion 30 is unable to fully exert its repulsive force compared to when the coating film is removed. Therefore, the second ratio, which is the ratio of the third rebound force F3 to the fourth rebound force F4, is less than 100%. On the other hand, in the first repulsive force F1, where the connection portion 30 is positioned at one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the positioning area 67b (thin-walled portion)), the stress is evenly distributed throughout the contact point (positioning area 67b (thin-walled portion)) of the coating film with the load-applying member 110. Therefore, the coating film is compressed radially while maintaining its extension along the axial direction. As a result, each connection portion 30 is also maintained in a state of extension along the axial direction. This ensures sufficient repulsive force of each connection portion 30 and the coating film. Therefore, the first ratio, which is the ratio of the first repulsive force F1 to the second repulsive force F2, can be made to exceed 100%. Furthermore, among the multiple non-placed regions 67a and placed regions 67b in the circumferential direction, it is sufficient that at least one non-placed region 67a and one placed region 67b adjacent to that non-placed region 67a have a thickness greater than that of the placed region 67b. Preferably, in all of the multiple non-placed regions 67a and placed regions 67b in the circumferential direction, the non-placed region 67a has a thickness greater than that of the placed region 67b. Similarly, among the multiple non-placed areas 67a and placed areas 67b in the axial direction, it is sufficient that at least one non-placed area 67a and one placed area 67b adjacent to that non-placed area 67a have a thickness greater than that of the placed area 67b. Preferably, in all of the multiple non-placed areas 67a and placed areas 67b in the axial direction, the non-placed area 67a has a thickness greater than that of the placed area 67b. The method for making the non-placed area 67a of the connecting portion 30 in the coating film thicker than the placed area 67b of the connecting portion 30 in the coating film is not particularly limited, but for example, it can be formed by first forming the first coating film 66 by impregnating the cylindrical portion 10 with a resin material, and then locally reapplying the same type of resin material to the non-placed area 67a of the connecting portion 30 in the first coating film 66. In addition to making the non-placement area 67a of the connection portion 30 thicker, pretension may also be added to the non-placement area 67a, for example. With such a configuration, in the third repulsive force F3 in which the connection portion 30 is positioned to avoid one end 100a of the stent 100, tension can be generated well from both ends of the coating film (both ends in the axial direction) toward the contact point with the load-applying member 110 (non-placement area 67a (thickened portion)). Therefore, the entire coating film can be bent in a substantially V-shape starting from the contact point with the load-applying member 110 (non-placement area 67a (thickened portion)).

[0028] However, the present invention is not limited to this example in which the stent 100 is configured such that the first ratio exceeds 100% and the second ratio falls below 100%. For example, the rigidity of the boundary portion (e.g., one end 31 and the other end 32) between the connecting portion 30 and the adjacent zigzag extension portion 20 (each of the tip-side zigzag extension portion 20 and the base-side zigzag extension portion 20) may be lower than the rigidity of other parts of the connecting portion 30 (e.g., the intermediate portion 33). Here, when the rigidity of the boundary portion (one end 31 and the other end 32) of the connecting portion 30 is lower than the rigidity of other parts of the connecting portion 30, it means that when a force is applied radially inward to the connecting portion 30, the amount of radially inward displacement due to elastic deformation is smaller at other parts of the connecting portion 30 than at the boundary portion. With this configuration, in the third repulsive force F3, where the connection portion 30 is positioned to avoid one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the coating), each connection portion 30 can easily bend in a direction intersecting the axial direction in accordance with the bending of the coating. Therefore, compared to the case where the coating is removed, each connection portion 30 cannot fully exert its repulsive force. Consequently, the second ratio, which is the ratio of the third repulsive force F3 to the fourth repulsive force F4, falls below 100%. On the other hand, in the first rebound force F1, where the connecting portion 30 is positioned at one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the connecting portion 30), stress concentrates on the relatively rigid intermediate portion 33 of the connecting portion 30. This suppresses bending of the coating film and maintains the state in which the connecting portion 30 extends along the axial direction. As a result, sufficient rebound force can be secured for both the connecting portion 30 and the coating film. Therefore, the first ratio, which is the ratio of the first rebound force F1 to the second rebound force F2, can be made to exceed 100%. Furthermore, for at least one of the multiple connecting portions 30 arranged in the circumferential direction, the rigidity of the boundary portion (one end 31 and the other end 32) between the connecting portion 30 and the zigzag extension portion 20 should be lower than the rigidity of other parts of the connecting portion 30. Preferably, for all of the multiple connecting portions 30 arranged in the circumferential direction, the rigidity of the boundary portion of the connecting portion 30 should be lower than the rigidity of other parts of the connecting portion 30. Similarly, for at least one of the multiple connecting portions 30 arranged in the axial direction, the rigidity of the boundary portion (one end 31 and the other end 32) between the connecting portion 30 and the zigzag extension portion 20 should be lower than the rigidity of other parts of the connecting portion 30. Preferably, for all of the multiple connecting portions 30 arranged in the axial direction, the rigidity of the boundary portion of the connecting portion 30 is lower than the rigidity of other parts of the connecting portion 30. The method for making the rigidity of the boundary portion (one end 31 and the other end 32) between the connecting portion 30 and the zigzag extension portion 20 lower than the rigidity of other parts of the connecting portion 30 is not particularly limited, but for example, the width dimension (dimension in the direction perpendicular to the extension direction) of the boundary portion (same as above) of the connecting portion 30 may be made smaller than the width dimension (same as above) of other parts of the connecting portion 30. Also, notches or grooves (not shown) may be formed in the boundary portion of the connecting portion 30 (the width dimension of the wire constituting the cylindrical portion 10 may be locally reduced). In addition, the thickness dimension of the boundary portion (same as above) of the connecting portion 30 may be made smaller than the thickness dimension of other parts of the connecting portion 30. Furthermore, these methods may be appropriately combined depending on the desired rigidity of the connecting portion 30.

[0029] Furthermore, in the present invention, the non-placement region 67a of the connecting portion 30 in the coating film (for example, the first coating film 66) may be made thicker than the placement region 67b of the connecting portion 30 in the coating film (for example, the first coating film 66), and the rigidity of the boundary portion (one end 31 and the other end 32) between the connecting portion 30 and the adjacent zigzag extension portion 20 may be lower than the rigidity of other parts (intermediate portion) of the connecting portion 30. With this configuration, it is possible to more reliably ensure that the first proportion exceeds 100% and the second proportion falls below 100%.

[0030] In the present invention, the method for configuring the first ratio to be greater than 100% and the second ratio to be less than 100% is not limited to the example described above. For example, the above configuration may be achieved by appropriately setting one or more of the following: the material of the coating film (first coating film 66 and second coating film 68), the thickness dimensions of the coating film (same as above), the individual thickness and width dimensions of the connecting portion 30, the number of connecting portions 30 in the circumferential direction, the distance between adjacent connecting portions 30 in the circumferential direction, etc.

[0031] Also, when a load is applied to the location where the zigzag extending portion 20 is disposed in the stent 100, the repulsive force is defined as the fifth repulsive force F5 (see Fig. 5(a)). When a load is applied to the location where the zigzag extending portion 20 is disposed in the stent 100 from which the coating film has been removed, the repulsive force is defined as the sixth repulsive force F6. When the ratio of the fifth repulsive force F5 to the sixth repulsive force F6 (see Fig. 5(b)) is defined as the third ratio, it is preferable that the third ratio is a value between the first ratio and the second ratio. That is, it is preferable that <F5 / F6<1. According to such a configuration, in the zigzag extending portion 20, the repulsive force (radial force) hardly changes regardless of the presence or absence of the coating film, and the stent 100 can exhibit stable shape retention. However, in the present invention, the magnitude relationship and ratio of the first repulsive force F1 to the sixth repulsive force F6 are not limited to the above examples, and can be appropriately set according to the use of the stent 100 and the desired expansion force of the stent 100.

[0032] 〔Second Embodiment〕 Next, the second embodiment will be described. The stent 100 according to the present embodiment is different from the stent 100 according to the above first embodiment in the points described below, and is configured in the same manner as the stent 100 according to the above first embodiment in other points.

[0033] In the case of the present embodiment, unlike the first embodiment, the second ratio exceeds 100% and the first ratio is less than 100%. That is, F3 / F4>1 and F1 / F2<1. Even with such a configuration, as described above, even if the coating film is partially peeled off unintentionally at the location where the connecting portion 30 in the stent 100 is disposed, with respect to the repulsive force (radial force) at that location, the second repulsive force F2 and the fourth repulsive force F4 are in a complementary relationship. Therefore, after the stent 100 is implanted, an unintentional shape change of the stent 100 can be suppressed. More specifically, the second rebound force F2 is preferably, for example, 1.01 times or more and 2 times or less the first rebound force F1, and more preferably 1.05 times or more and 2 times or less the first rebound force F1. Similarly, the third rebound force F3 is preferably, for example, 1.01 times or more and 2 times or less of the fourth rebound force F4, and more preferably 1.02 times or more and 2 times or less of the fourth rebound force F4.

[0034] In this embodiment, as an example, the repulsive force of the stent 100 is a value measured using a tensile-compression testing machine (AGS-5kNX, manufactured by Shimadzu Corporation, load cell: AGS-X·EZ-X 50N). More specifically, first, the stent 100 is placed on the horizontal plate 120. Next, the end face 110a of the load-applying member 110 (for example, a flat plate member with a thickness of 1 mm) is placed on one end of the stent 100 in the radial direction. At this time, the end face 110a of the load-applying member 110 is positioned parallel to the horizontal plate 120. Furthermore, the width dimensions of the load-applying member 110 and the horizontal plate 120 are larger than the outer diameter of the stent 100, and the entire radial portion of the stent 100 is contained within the respective widths of the load-applying member 110 and the horizontal plate 120. In addition, the entire axial portion of the stent 100 is positioned on the horizontal plate 120. Next, the load-applying member 110 is moved radially, and the rebound force is measured while the stent 100 is compressed to 63% of its natural outer diameter.

[0035] As a method for creating a configuration in which the second ratio exceeds 100% and the first ratio falls below 100%, one example is to make the rigidity of the intermediate part (intermediate part 33) in the axial direction of the connection part 30 lower than the rigidity of other parts of the connection part 30. This makes it possible to achieve a configuration in stent 100 where the second proportion exceeds 100% and the first proportion falls below 100%. More specifically, in the first repulsive force F1, when the connection portion 30 is located at one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses on the connection portion 30), the connection portion 30 located at one end 100a easily bends in a direction intersecting the axial direction, starting from the intermediate portion 33, which has relatively lower rigidity. Furthermore, the coating film also bends in a roughly V-shape, starting from the point of contact with the load-applying member 110, when viewed in a direction perpendicular to the load direction and in the radial direction (for example, the left-right direction in Figure 4(a)). As a result, the other connection portions 30 not located at one end 100a also bend in a direction intersecting the axial direction, following the bending of the coating film. Therefore, compared to the case where the coating film is removed, each of the connection portions 30 is unable to fully exert its repulsive force. Consequently, the first ratio, which is the ratio of the first repulsive force F1 to the second repulsive force F2, falls below 100%. On the other hand, in the third repulsive force F3, where the connection portion 30 is positioned to avoid one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the coating film), stress concentration in the intermediate portion 33 of the connection portion 30 is suppressed, and each connection portion 30 maintains an axial extension. Therefore, since sufficient repulsive force from the coating film and repulsive force from the connection portion 30 can be secured, the second ratio, which is the ratio of the third repulsive force F3 to the fourth repulsive force F4, can be made to exceed 100%. Furthermore, for at least one of the multiple connecting portions 30 arranged in the circumferential direction, the rigidity of the intermediate portion (intermediate portion 33) in the axial direction of the connecting portion 30 should be lower than the rigidity of the other parts of the connecting portion 30. Preferably, for all of the multiple connecting portions 30 arranged in the circumferential direction, the rigidity of the intermediate portion (intermediate portion 33) in the axial direction of the connecting portion 30 should be lower than the rigidity of the other parts of the connecting portion 30. Similarly, for at least one of the multiple connecting portions 30 arranged in the axial direction, the rigidity of the intermediate portion (intermediate portion 33) of the connecting portion 30 in the axial direction is lower than the rigidity of the other parts of the connecting portion 30. Preferably, for all of the multiple connecting portions 30 arranged in the axial direction, the rigidity of the intermediate portion (intermediate portion 33) of the connecting portion 30 in the axial direction is lower than the rigidity of the other parts of the connecting portion 30.

[0036] The method for making the rigidity of the intermediate portion 33 of the connection portion 30 lower than the rigidity of other parts of the connection portion 30 is not particularly limited, but for example, the width dimension of the intermediate portion 33 of the connection portion 30 (dimension in a direction perpendicular to the extension direction) may be made smaller than the width dimension of other parts of the connection portion 30 (same as above). Also, notches or grooves (not shown) may be formed in the intermediate portion 33 of the connection portion 30 (the width dimension of the wire constituting the cylindrical portion 10 may be locally reduced). In addition, the thickness dimension of the intermediate portion 33 of the connection portion 30 may be made smaller than the thickness dimension of other parts of the connection portion 30. Furthermore, these methods may be appropriately combined depending on the desired rigidity of the connection portion 30.

[0037] Furthermore, as a method to create a configuration in which the second proportion exceeds 100% and the first proportion falls below 100%, for example, the area 67b where the connection portion 30 is located in the coating film (e.g., the first coating film 66) may be made thicker than the area 67a where the connection portion 30 is not located in the coating film (e.g., the first coating film 66). With this configuration, when the connection portion 30 is positioned at one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the positioning area 67b (the thick part of the coating film)), the coating film is pressed by the load-applying member 110 and easily bends in a direction intersecting the axial direction, starting from the non-positioning area 67a (the thick part). More specifically, when viewed in a direction perpendicular to the load direction and radially (for example, the left-right direction in Figure 4(a)), the coating film bends in a roughly V-shape starting from the point of contact with the load-applying member 110. Furthermore, each connection portion 30 also bends in a direction intersecting the axial direction, following the bending of the coating film in this manner, so each connection portion 30 is unable to exert its repulsive force as much as when the coating film is removed. Therefore, the first ratio, which is the ratio of the first repulsive force F1 to the second repulsive force F2, falls below 100%. On the other hand, in the third repulsive force F3, where the connection portion 30 is positioned to avoid one end 100a of the stent 100 (i.e., the load-applying member 110 mainly presses against the non-placement area 67a (thin-walled portion)), the stress is evenly distributed throughout the contact point with the load-applying member 110 in the coating film (the non-placement area 67a (thin-walled portion)). As a result, the coating film is compressed radially while maintaining its extension along the axial direction. Consequently, each connection portion 30 is also maintained in a state of extension along the axial direction. This ensures sufficient repulsive force for each connection portion 30 and the coating film. Therefore, the second ratio, which is the ratio of the third repulsive force F3 to the fourth repulsive force F4, can be made to exceed 100%. Furthermore, among the multiple non-placed regions 67a and placed regions 67b in the circumferential direction, it is sufficient that at least one non-placed region 67a and one placed region 67b adjacent to that non-placed region 67a have a thicker wall than the non-placed region 67a. Preferably, for all of the multiple non-placed regions 67a and placed regions 67b in the circumferential direction, the placed region 67b has a thicker wall than the non-placed region 67a. Similarly, among the multiple non-placed areas 67a and placed areas 67b in the axial direction, it is sufficient that at least one non-placed area 67a and one placed area 67b adjacent to that non-placed area 67a have a thicker wall than the non-placed area 67a. Preferably, for all of the multiple non-placed areas 67a and placed areas 67b in the axial direction, the placed areas 67b have a thicker wall than the non-placed areas 67a. The method for making the area 67b where the connecting portion 30 is located in the coating film thicker than the area 67a where the connecting portion 30 is not located in the coating film is not particularly limited. For example, it can be formed by first forming the first coating film 66 by impregnating the cylindrical portion 10 with a resin material, and then locally reapplying the same type of resin material to the area 67b where the connecting portion 30 is located in the first coating film 66. In addition to making the arrangement area 67b of the connection portion 30 thicker, pretension may also be added to the arrangement area 67b, for example. With this configuration, in the first repulsive force F1 where the connection portion 30 is positioned at one end 100a of the stent 100, tension can be generated effectively from both ends of the coating film (both ends in the axial direction) toward the contact point with the load-applying member 110 (arrangement area 67b (thickened portion)). Therefore, the entire coating film can be bent into a roughly V-shape starting from the contact point with the load-applying member 110 (arrangement area 67b (thickened portion)).

[0038] Furthermore, in the present invention, the area 67b in which the connecting portion 30 is located in the coating film (for example, the first coating film 66) may be made thicker than the area 67a in which the connecting portion 30 is not located in the coating film (for example, the first coating film 66), and the rigidity of the intermediate portion (intermediate portion 33) in the axial direction of the connecting portion 30 may be lower than the rigidity of other parts of the connecting portion 30. With this configuration, it is possible to more reliably ensure that the second proportion exceeds 100% and the first proportion falls below 100%.

[0039] In the present invention, the method of configuring such that the second ratio exceeds 100% and the first ratio is less than 100% is not limited to the above example. For example, by appropriately setting any one or more of the material of the coating film (the first coating film 66 and the second coating film 68), the thickness dimension of the coating film (the same as above), the individual thickness dimensions and width dimensions of the connecting portion 30, the number of the connecting portions 30 in the circumferential direction, the separation distance between adjacent connecting portions 30 in the circumferential direction, etc., the above configuration may be realized.

[0040] Further, when a load is applied to the location where the zigzag extending portion 20 is arranged in the stent 100, the repulsive force is defined as the fifth repulsive force F5. When a load is applied to the location where the zigzag extending portion 20 is arranged in the stent 100 from which the coating film has been removed, the repulsive force is defined as the sixth repulsive force F6. When the ratio of the fifth repulsive force F5 to the sixth repulsive force F6 is defined as the third ratio, it is preferable that the third ratio exceeds 100%. That is, it is preferable that F1 / F2 < F5 / F6 < F3 / F4. According to such a configuration, the expansion force of the zigzag extending portion 20 can be sufficiently ensured by the coating film.

[0041] <Modified Example of the Second Embodiment> Next, the stent 100 according to the modified example of the second embodiment will be described. The stent 100 according to this modified example is different from the stent 100 according to the above first and second embodiments in the points described below, and is configured in the same manner as the stent 100 according to the above first and second embodiments in other points.

[0042] In the case of this modified example, the stent 100 has a portion (hereinafter, the first portion) configured such that the first ratio exceeds 100% and the second ratio is less than 100%, and a portion (hereinafter, the second portion) configured such that the second ratio exceeds 100% and the first ratio is less than 100% at different locations in the axial direction. With this configuration, even if the coating film partially peels off unintentionally over a wide area in the axial direction of the stent 100, the expansion force of the stent 100 can be maintained more effectively by complementarily combining the repulsive force (second repulsive force F2) when the connection portion 30 is positioned at one end 100a and the repulsive force (fourth repulsive force F4) when the connection portion 30 is positioned away from the one end 100a.

[0043] More specifically, in this modified example, for example, in the first part, as in the first embodiment, the area 67a of the non-placed portion 30 in the coating film (e.g., first coating film 66) is thicker than the area 67b of the placed portion 30 in the coating film (e.g., first coating film 66), and the rigidity of the boundary portion (one end 31 and the other end 32) between the placed portion 30 and the adjacent zigzag extension portion 20 is lower than the rigidity of other parts (intermediate part) of the placed portion 30. On the other hand, in the second part, as in the second embodiment, the area 67b of the placed portion 30 in the coating film (e.g., first coating film 66) is thicker than the area 67a of the non-placed portion 30 in the coating film (e.g., first coating film 66), and the rigidity of the intermediate part (intermediate part 33) in the axial direction of the placed portion 30 is lower than the rigidity of other parts of the placed portion 30. This allows the stent 100 to have a configuration comprising a portion (first portion) in which the first proportion is greater than 100% and the second proportion is less than 100%, and a portion (second portion) in which the second proportion is greater than 100% and the first proportion is less than 100%. For example, the first and second parts were arranged alternately in the axial direction. It should be noted that the method for realizing the above-described configuration in the present invention is not limited to this example. For example, it may be realized by appropriately setting the elastic modulus of the coating film material (first coating film 66 and second coating film 68) and the thickness dimension of the coating film for the first and second parts, respectively. Alternatively, it may be realized by appropriately setting one or more of the following for the first and second parts, respectively: the rigidity of the connecting portion 30, the number of connecting portions 30 in the circumferential direction, and the distance between adjacent connecting portions 30 in the circumferential direction.

[0044] Although embodiments and 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. It also includes various modifications, improvements, and other forms as long as the objective of the present invention is achieved.

[0045] 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.

[0046] This embodiment encompasses the following technical concepts. (1) A stent having a cylindrical portion, The aforementioned cylindrical portion is The cylindrical portion has multiple zigzag extending portions that extend circumferentially while oscillating in a zigzag pattern in the axial direction, and these portions are arranged to be offset from each other in the axial direction, It has connecting parts that connect adjacent zigzag extensions in the axial direction, The stent has a covering film that covers the cylindrical portion, The load-applying member was moved from one side to the other, and a load was applied to the stent that compresses it radially. The rebound force of the stent at that time was then measured, and the results were as follows: With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent, the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the first repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned at one end of the stent from which the coating film has been removed, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the second repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from one end of the stent, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the third repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from the one end of the stent from which the coating film has been removed, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the fourth repulsive force. The ratio of the first rebound force to the second rebound force is defined as the first ratio. If the ratio of the third rebound force to the fourth rebound force is taken as the second ratio, A stent in which one of the first and second proportions exceeds 100%, and the other falls below 100%. (2) The stent according to (1), wherein the connection portion is arranged at one or more locations in the axial direction of the stent and at multiple locations in the circumferential direction. (3) The stent according to (1) or (2), wherein the connection parts are arranged at multiple locations in the axial direction of the stent. (4) The stent according to (1) or (2), wherein the first ratio is greater than 100% and the second ratio is less than 100%. (5) The fifth rebound force when the load is applied to the location in the stent where the zigzag extension is located, The sixth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed. If the ratio of the fifth rebound force to the sixth rebound force is taken as the third ratio, The stent described in (4), wherein the third proportion is a value between the first proportion and the second proportion. (6) The stent according to (1) or (2), wherein the second ratio is greater than 100% and the first ratio is less than 100%. (7) The fifth rebound force when the load is applied to the location in the stent where the zigzag extension is located, The sixth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed. If the ratio of the fifth rebound force to the sixth rebound force is taken as the third ratio, The stent described in (6) above, wherein the third proportion exceeds 100%. (8) The stent according to any one of (1) to (8), wherein the coating film has a two-layer structure. [Explanation of symbols]

[0047] 10. Cylindrical part 20 Multiple zigzag extensions 22 1st extension part 23 Second extension part 25 1st top 26 2nd top 30 Connection part 31 One end 32 Other end 33 Middle section 40 End winding section 42 Yamabe 44 Tanibe 46 Strut section 66 First coating film 67a Non-placed area of ​​the connection part 67b Placement area of ​​connection section 68 Second coating film 100 stents One end 100a The other end 100b 110 Load-applying member 110a end face 120 horizontal board F1 First rebound force F2 Second rebound force F3 Third rebound force F4 4th rebound force F5 Fifth rebound force F6 6th rebound force

Claims

1. A stent having a cylindrical portion, The aforementioned cylindrical portion is The cylindrical portion has multiple zigzag extending portions that extend circumferentially while oscillating in a zigzag pattern in the axial direction, and these portions are arranged to be offset from each other in the axial direction, It has connecting parts that connect adjacent zigzag extensions in the axial direction, The stent has a covering film that covers the cylindrical portion, The load-applying member was moved from one side to the other, and a load was applied to the stent that compresses it radially. The rebound force of the stent at that time was then measured, and the results were as follows: With the rotation angle of the stent around its axis adjusted so that the connecting portion is positioned at one end of the stent, the repulsive force when the load is applied to the location of the connecting portion in the stent is defined as the first repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned at one end of the stent from which the coating film has been removed, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the second repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned away from one end of the stent, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the third repulsive force. With the rotation angle of the stent around its axis adjusted so that the connection portion is positioned at a location avoiding the one end of the stent from which the coating film has been removed, the repulsive force when the load is applied to the location of the connection portion in the stent is defined as the fourth repulsive force. The ratio of the first rebound force to the second rebound force is defined as the first ratio. If the ratio of the third repulsive force to the fourth repulsive force is taken as the second ratio, A stent in which one of the first and second proportions exceeds 100%, and the other falls below 100%.

2. The stent according to claim 1, wherein the connection portion is arranged at one or more locations in the axial direction of the stent and at multiple locations in the circumferential direction.

3. The stent according to claim 1 or 2, wherein the connection portions are arranged at multiple locations in the axial direction of the stent.

4. The stent according to claim 1 or 2, wherein the first ratio is greater than 100% and the second ratio is less than 100%.

5. The fifth rebound force is defined as the rebound force when the load is applied to the location where the zigzag extension is positioned in the stent. The sixth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed. If the ratio of the fifth repulsive force to the sixth repulsive force is taken as the third ratio, The stent according to claim 4, wherein the third ratio is a value between the first ratio and the second ratio.

6. The stent according to claim 1 or 2, wherein the second ratio is greater than 100% and the first ratio is less than 100%.

7. The fifth rebound force is defined as the rebound force when the load is applied to the location where the zigzag extension is positioned in the stent. The sixth repulsive force is defined as the repulsive force when the load is applied to the location where the zigzag extension is located in the stent from which the coating film has been removed. If the ratio of the fifth repulsive force to the sixth repulsive force is taken as the third ratio, The stent according to claim 6, wherein the third proportion exceeds 100%.

8. The stent according to claim 1 or 2, wherein the coating film has a two-layer structure.

Images