Stent

Abstract

This stent comprises a tubular part and a locking part. The tubular part is formed by weaving wires and is configured to be expandable. The locking part is formed of a wire and is configured to protrude to the outside of the tubular part when the tubular part is expanded. The locking part has: an intersection section where the wires cross each other when viewed in a radial direction of the tubular part; and an annular section which forms an annular shape with the intersection section serving as a base point.

Description

stents

[0001] The technology disclosed herein relates to stents.

[0002] For example, stent placement is used when a narrowed or blocked area (hereinafter simply referred to as "stenosis") occurs in a body lumen (digestive organs such as the bile duct, gallbladder, pancreas, esophagus, duodenum, small intestine, and large intestine, blood vessels, ureters, trachea, etc.) Stent placement is a procedure for securing the lumen by placing a cylindrical stent at the location of the narrowed area or at a position that bypasses the narrowed area.

[0003] Generally, a self-expanding stent is used in stent placement. A self-expanding stent is a stent that contracts radially due to its elasticity when a compressive force is applied, and expands radially when the compressive force is released. A self-expanding stent is formed, for example, by braiding wires.

[0004] A self-expanding stent is mounted in a contracted state on a delivery system and transported to the placement site. When released from the delivery system, it self-expands and is placed in that state. If the stent moves out of position (migration) after placement, the function of the stent may be reduced or other problems may occur, so the stent must be able to stably maintain its position once placed.

[0005] Conventionally, in order to prevent the stent from shifting position, a configuration has been proposed in which a locking portion having an anchoring function is provided on the outside of the tubular portion of the stent (see, for example, Patent Document 1).

[0006] International Publication No. 2020 / 194506

[0007] The above-mentioned conventional stents are difficult to reduce in diameter due to the presence of the locking portion provided on the outside of the tubular portion, and there is room for improvement in terms of ease of mounting on a delivery system.

[0008] This specification discloses a technique that can solve the above-mentioned problems.

[0009] The technology disclosed in this specification can be realized, for example, in the following forms.

[0010] (1) The stent disclosed in this specification includes a tubular portion and an engaging portion. The tubular portion is formed by weaving wires and is configured to be expandable. The engaging portion is formed from the wires and is configured to protrude outward from the tubular portion when the tubular portion is expanded. The engaging portion has an intersection portion where the wires intersect when viewed in the radial direction of the tubular portion, and an annular portion having a base point at the intersection portion.

[0011] This stent has a locking portion that protrudes outward from the tubular portion when the tubular portion is expanded, and the anchoring effect of the locking portion prevents the stent from shifting after placement. Furthermore, because the locking portion has an intersection and a ring portion, the locking portion is relatively narrow at the intersection. Therefore, even with a stent that has a locking portion, the stent can be easily reduced in diameter, improving the ease of mounting the stent on a delivery system.

[0012] (2) In the stent, the engaging portion may have a plurality of combinations of the crossing portion and the annular portion. With this configuration, one engaging portion contacts the body wall at a plurality of locations, thereby effectively reducing stress concentration on the body wall due to the engaging portion, thereby effectively suppressing bleeding and perforation in the body wall and effectively suppressing displacement of the stent after placement.

[0013] (3) In the above stent, an angle θ1 formed between an imaginary line connecting the intersection in one of the combinations and a portion of the wires constituting the annular portion farthest from the intersection and an imaginary line connecting the intersection in another of the combinations and a portion of the wires constituting the annular portion farthest from the intersection may be greater than 0 degrees and less than 180 degrees. This configuration makes it easier to reduce the diameter of a stent having a locking portion having a plurality of the above combinations, thereby improving the ease of mounting the stent on a delivery system.

[0014] (4) In the above stent, the annular portion may have an asymmetric shape with respect to an imaginary line connecting the intersection and the portion of the wire constituting the annular portion farthest from the intersection as an axis. With this configuration, the anchoring effect of the locking portion can be set to an appropriate value that is neither too large nor too small, and it is possible to effectively suppress bleeding or perforation in the body wall due to contact with the locking portion while also effectively suppressing displacement of the stent after placement.

[0015] (5) In the stent, the annular portion may be configured to have multiple annular portions formed from the intersection portion as a base point. This configuration can increase the anchoring effect of the locking portion and effectively prevent the stent from shifting after placement.

[0016] (6) In the stent, the annular portion may be configured to have multiple annular portions with different circumferential lengths, each of which is formed around the intersection. This configuration allows a cover to be easily and reliably formed in the area surrounded by the annular portions, thereby making it possible to, for example, reduce the thickness of the cover formed in the area.

[0017] (7) The stent may be configured to include a plurality of the locking portions located at different positions along the axial direction of the tubular portion, and the position of one of the locking portions may be different from the position of another of the locking portions in the circumferential direction of the tubular portion. With this configuration, the plurality of locking portions are arranged in a balanced manner along the axial and circumferential directions of the tubular portion, thereby achieving a balanced anchor effect and effectively suppressing displacement of the stent after placement.

[0018] (8) The stent may further include a resin cover covering at least a portion of the tubular portion, the cover also being disposed in the area surrounded by the annular portion. This configuration can more effectively reduce stress concentration on the body wall due to the anchoring portion, thereby more effectively suppressing bleeding and perforation in the body wall. Furthermore, the cover can prevent tumors, granulation tissue, etc. from entering the annular portion of the anchoring portion, facilitating removal.

[0019] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a stent, a method for manufacturing or using a stent, etc.

[0020] 1 is a perspective view showing the external configuration of the stent 10 in the first embodiment; an explanatory diagram showing the planar configuration of the stent 10 in the first embodiment; a developed view of the main body portion 100 of the stent 10 in the first embodiment, developed in the circumferential direction D1; an explanatory diagram showing a braiding method of the main body portion 100 in the first embodiment; an explanatory diagram showing a braiding method of the main body portion 100 in the first embodiment; an explanatory diagram showing an example of how to use the stent 10 in the first embodiment; a developed view of the main body portion 100a constituting the stent 10 in the second embodiment; a developed view of the main body portion 100b constituting the stent 10 in the third embodiment; a developed view of the main body portion 100c constituting the stent 10 in the fourth embodiment; a developed view of the main body portion 100d constituting the stent 10 in the fifth embodiment.

[0021] A. First Embodiment: A-1. Configuration of Stent 10: FIG. 1 is a perspective view showing the external configuration of stent 10 in the first embodiment, and FIG. 2 is an explanatory diagram showing the planar configuration of stent 10 in the first embodiment. X, Y, and Z axes, which are orthogonal to each other, are shown in FIGS. 1 and 2. In the following description, for convenience, the positive Z-axis direction may be referred to as the upper side, and the negative Z-axis direction may be referred to as the lower side. Furthermore, FIG. 1 shows a state in which the central axis Ax of stent 10 (of a tubular portion 110 described below) is parallel to the Z-axis, but the stent 10 as a whole is configured to be bendable.

[0022] The stent 10 is a medical device that is placed at the location of a stenosis or at a position that bypasses the stenosis when a stenosis occurs in a body lumen (such as the bile duct, gallbladder, pancreas, esophagus, duodenum, small intestine, large intestine, or other digestive organs, blood vessels, ureters, or trachea) to maintain the lumen. The stent 10 is a self-expanding stent that elastically contracts radially when a compressive force is applied and expands radially when the compressive force is released. Figures 1 and 2 show the state of the stent 10 when expanded.

[0023] As shown in Fig. 1, the stent 10 of this embodiment is a so-called covered stent, and includes a main body 100 and a cover 200. For convenience, the cover 200 is shown by a dashed line in Fig. 1, and is not shown in Fig. 2.

[0024] 3 is a development view of the main body portion 100 of the stent 10 of the first embodiment developed in the circumferential direction D1. In this specification, the circumferential direction D1 refers to the circumferential direction centered on the central axis Ax of the tubular portion 110 of the main body portion 100, as shown in FIG. 2. The main body portion 100 is a part that constitutes the framework of the stent 10, and has the tubular portion 110, locking portions 120, and protrusions 130.

[0025] The tubular portion 110 is a portion that expands in diameter to become substantially cylindrical when the stent 10 is expanded. The radius of the tubular portion 110 when expanded is, for example, about 2 mm to 40 mm, and the length of the tubular portion 110 along the central axis Ax is, for example, about 20 mm to 200 mm. The radius of the tubular portion 110 is determined appropriately depending on the type, size, position, etc. of the body lumen in which the stent 10 is to be placed.

[0026] As shown in FIG. 3 , the tubular portion 110 is formed by weaving wires W. The weaving method of the tubular portion 110 is so-called hook weaving, and cells CE, which are approximately diamond-shaped voids surrounded by the wires W, are regularly arranged. The tubular portion 110 has multiple intersections 102 where the wires W cross each other without entangling, and multiple entangled portions 101 where an upwardly convex, approximately V-shaped portion of the wire W and a downwardly convex, approximately V-shaped portion of the wire W cross each other in a hook-like manner and entangle each other. In the entangled portions 101, the upwardly convex portion of the wire W and the downwardly convex portion of the wire W are connected inseparably but relatively movable. Therefore, the main body portion 100 can be bent as a whole and can maintain the bent state, allowing it to be easily placed in a curved biological lumen.

[0027] The protrusions 130 are generally V-shaped portions formed by the wire W, and protrude upward from the upper end of the tubular portion 110 or protrude downward from the lower end of the tubular portion 110. When the stent 10 is expanded, the protrusions 130 are generally parallel to the central axis Ax of the tubular portion 110. In this embodiment, six upwardly convex protrusions 130 are arranged consecutively in the circumferential direction D1 at the upper end of the tubular portion 110, and six downwardly convex protrusions 130 are arranged consecutively in the circumferential direction D1 at the lower end of the tubular portion 110.

[0028] The locking portions 120 are portions that protrude outward from the tubular portion 110 when the tubular portion 110 is expanded, thereby fulfilling their anchoring function. In this embodiment, two locking portions 120 (hereinafter also referred to as "upper locking portions 120u") are arranged discretely and evenly spaced in the circumferential direction D1 near the upper end of the tubular portion 110 (slightly below the upper end), and two locking portions 120 (hereinafter also referred to as "lower locking portions 120l") are arranged discretely and evenly spaced in the circumferential direction D1 below them. That is, the stent 10 of this embodiment has four locking portions 120. The shapes and sizes of the four locking portions 120 are substantially identical to one another. Furthermore, the positions of the upper locking portions 120u and the lower locking portions 120l are different in the circumferential direction D1 of the tubular portion 110. More specifically, the positions of the two locking portions 120 are offset by approximately 90 degrees from each other in the circumferential direction D1. Due to the presence of the locking portions 120, when the stent 10 is expanded, the maximum radius of the main body portion 100 (i.e., the distance L3 from the central axis Ax of the tubular portion 110 to the outermost point Pt of the locking portions 120) becomes larger than the radius of the tubular portion 110. The distance L3 is, for example, 4 mm or more and 50 mm or less.

[0029] The locking portion 120 is formed by a portion of the wire W that constitutes the entanglement portion 101. More specifically, as shown in FIG. 3 , the locking portion 120 is formed by providing a large amount of slack in a portion of one of the wires W that constitutes the entanglement portion 101 and twisting that portion. Therefore, the locking portion 120 has an intersection portion 121 where the wires W intersect when viewed radially from the tubular portion 110, and an annular portion 122 that is annular and has an origin at the intersection portion 121 when viewed radially from the tubular portion 110. In this embodiment, each locking portion 120 has one combination of the intersection portion 121 and the annular portion 122. Here, the annular shape refers to a shape that returns to the origin from a predetermined path, and the path may be curved, linear, or bent. In this embodiment, the shape of the region 123 surrounded by the annular portion 122 is approximately elliptical. Furthermore, the portions of the two wires W that intersect at the intersection 121 may be in contact with each other or may be spaced apart from each other.

[0030] In this embodiment, the wires W constituting the locking portion 120 are located in the same imaginary plane. The wires W constituting the locking portion 120 may or may not be located in the same imaginary plane.

[0031] The locking portion 120 is configured to extend obliquely downward from the connection portion with the tubular portion 110 when the stent 10 is expanded. The inclination of the locking portion 120 when the stent 10 is expanded (i.e., the angle between the central axis Ax of the tubular portion 110 and an imaginary line VL0 (see FIG. 1 ) connecting the intersection 121 and the portion P0 of the wire W constituting the annular portion 122 farthest from the intersection 121) may be, for example, 20 degrees or more and 70 degrees or less, or may be, for example, 30 degrees or more and 60 degrees or less. By configuring the locking portion 120 to extend obliquely downward from the connection portion with the tubular portion 110, the amount of deformation of the locking portion 120 can be reduced when the stent 10 is contracted and housed in a housing (sheath) constituting a delivery system, and the load imposed by the locking portion 120 on the inner wall of the housing can be reduced.

[0032] The cover 200 is formed of a resin such as polyurethane or silicone, and covers at least a portion of the main body 100. In this embodiment, the cover 200 covers the entire main body 100. The cover 200 is also disposed in the area surrounded by the wire W of the locking portion 120, including the area 123 surrounded by the annular portion 122 of the locking portion 120.

[0033] In this embodiment, the tubular portion 110, the locking portion 120, and the protruding portion 130 that make up the main body 100 are continuously formed by weaving a single wire W. However, these may also be formed from separate wires W. The wire W is formed from a superelastic alloy such as a nickel-titanium (Ni-Ti) alloy. The wire W may also be formed from other metals such as stainless steel, tantalum, titanium, cobalt-chromium alloy, magnesium alloy, etc., or from a resin such as polyolefin, polyester, or fluororesin. The diameter of the wire W is, for example, approximately 0.05 mm to 0.5 mm.

[0034] A-2. Manufacturing Method of Stent 10: Next, an example of a manufacturing method of the stent 10 of this embodiment will be described. First, the main body 100 is manufactured by hook knitting the wire W. The method of manufacturing a stent by hook knitting is publicly known, as described in Japanese Patent No. 3708923, for example, but will be briefly described below.

[0035] 4 and 5 are explanatory diagrams showing a method for weaving the main body 100 in the first embodiment. Each of the columns in Fig. 4 and 5 shows, in the form of a development, the procedure for producing the main body 100 by weaving the wire W using a jig JG having a plurality of pins PN erected on the outer circumferential surface of a cylindrical member. Hereinafter, the distance between two diagonally adjacent pins PN on the jig JG is referred to as the diagonal distance LP.

[0036] 4A, an end of the wire W is fixed to a pin PN at a predetermined position of the jig JG to set the starting point ST, and the wire W is then hung in a zigzag pattern between the pins PN from the starting point ST. More specifically, the wire W is extended from the starting point ST diagonally upward and left to hang it above the pin PN, then the wire W is extended diagonally downward and left by 1×LP to hang it below the pin PN, and then the wire W is extended diagonally upward and left by 2×LP to hang it above the pin PN. This operation is repeated until the wire W reaches a position corresponding to the upper end of the cylindrical portion 110.

[0037] Next, as shown in section B of FIG. 4 , following the formation of the wire W in section A of FIG. 4 , the wire W is hung between the pins PN in a zigzag pattern so as to form six upwardly convex V-shaped portions (protrusions 130) from a position corresponding to the upper end of the tubular portion 110. More specifically, the six protrusions 130 are formed by extending the wire W diagonally upward and left by 1×LP and hanging it above the pins PN, and then extending the wire W diagonally downward and left by 1×LP and hanging it below the pins PN. At this time, at the positions of the pins PN where the wire W is already wound, the wires W cross each other in a hook-like manner, forming entanglement portions 101. This also applies to subsequent processes. Furthermore, at positions where the wire W passes obliquely without being wound around the pins PN, the wires W cross each other without entangling, forming intersection portions 102. This also applies to subsequent processes.

[0038] Next, as shown in column C of Fig. 4, following the formation of the wire W in column B of Fig. 4, the wire W is laid between the pins PN in a zigzag pattern so as to form four downwardly convex V-shaped portions. More specifically, the operation of extending the wire W diagonally downward and left by 1 x LP to lay it below the pin PN, and the operation of extending the wire W diagonally upward and left by 1 x LP to lay it above the pin PN are repeated four times. Thereafter, the wire W is extended diagonally downward and left by 2 x LP.

[0039] Next, as shown in section D of FIG. 5 , following the formation of the wire W in section C of FIG. 4 , the same operations as in section C of FIG. 4 are repeated until the wire W reaches a position corresponding to the lower end of the tubular portion 110. However, at the position where the locking portion 120 is to be formed, the unprocessed locking portion 120 is formed. More specifically, at the position where the locking portion 120 is to be formed, the portion of the wire W constituting the entangled portion 101 is loosened and twisted to form a ring by hanging it on a pin PN. This forms the unprocessed locking portion 120, which has an intersection 121 where the wires W intersect with each other and a ring-shaped portion 122 that is annular from the intersection 121. Section E of FIG. 5 shows the state where the wire W reaches a position corresponding to the lower end of the tubular portion 110 after four unprocessed locking portions 120 have been formed.

[0040] Next, as shown in section F of Figure 5, following the formation of the wire W in section E of Figure 5, the wire W is zigzag-hung between the pins PN to form six downwardly convex V-shaped portions (protrusions 130). That is, the protrusions 130 are formed by extending the wire W diagonally downward and left by 1 x LP to hook it under the pin PN, and then extending the wire W diagonally upward and left by 1 x LP to hook it over the pin PN. After forming the sixth protrusion 130, the wire W is extended to the starting point ST, and both ends of the wire W are connected at the starting point ST by, for example, crimping to form the crimped portion 114. Through the above steps, the main body 100 before the processing of the locking portion 120 is produced.

[0041] Next, for example, using a jig, the unprocessed locking portion 120 is lifted and fixed in a state so that it protrudes from the cylindrical portion 110 toward the outer periphery, and a heat treatment for shape memory (for example, at 350 to 600°C for 5 to 30 minutes) is performed. This forms the locking portion 120 that protrudes from the cylindrical portion 110 toward the outer periphery when expanded.

[0042] Finally, the cover 200 is formed at a predetermined location on the main body 100. At this time, the cover 200 is also placed in the region 123 surrounded by the annular portion 122 of the locking portion 120. Through the above steps, the manufacture of the stent 10 of this embodiment is completed.

[0043] A-3. Method of Using the Stent 10: Next, an example of a method of using the stent 10 will be described. Figure 6 is an explanatory diagram showing an example of a method of using the stent 10 of the first embodiment. Note that part of the wire W is not shown in Figure 6.

[0044] First, the stent 10 is mounted on a delivery system in a contracted state. When the stent 10 is in the contracted state, the anchoring portions 120 are folded so as not to protrude radially outward from the tubular portion 110. Next, the delivery system transports the stent 10 to an indwelling position (the position of the stenosis or a position bypassing the stenosis) within the biological lumen 20 shown in FIG. 6 , and the stent 10 is released from the delivery system at the indwelling position. Accordingly, the stent 10 expands due to its self-expanding properties. When the stent 10 expands, each anchoring portion 120 protrudes radially outward from the tubular portion 110. Therefore, as shown in column A of FIG. 6 , the anchoring portions 120 contact the body wall 21 of the biological lumen 20, functioning as anchors and preventing the stent 10 from migrating. As described above, since the engaging portion 120 has the annular portion 122, stress concentration on the body wall 21 due to the engaging portion 120 contacting the body wall 21 is alleviated, and bleeding and perforation in the body wall 21 can be suppressed.

[0045] Furthermore, the locking portion 120 is oriented so as to extend obliquely downward from the connection portion with the tubular portion 110. Therefore, as shown in column B of Fig. 6 , when a downward force acts on the stent 10, the locking portion 120 changes angle with the connection portion with the tubular portion 110 as a fulcrum, increasing the inclination of the locking portion 120 relative to the tubular portion 110. As a result, the outer diameter of the stent 10 becomes even larger, the anchor function of the locking portion 120 is enhanced, and displacement of the stent 10 is more effectively suppressed.

[0046] Furthermore, if the stent 10 becomes blocked again by a tumor, granulation tissue, or the like, and a large downward force is applied to the stent 10 when the stent 10 is being removed, the engaging portion 120 will assume a position in which it extends obliquely upward from the connection portion with the tubular portion 110, thereby reducing the anchor effect of the engaging portion 120. As a result, the stent 10 can be easily removed.

[0047] A-4. Effects of the First Embodiment: As described above, the stent 10 of this embodiment includes a tubular portion 110 and an engaging portion 120. The tubular portion 110 is formed by weaving wires W and is configured to be expandable. The engaging portion 120 is formed from wires W and is configured to protrude outward from the tubular portion 110 when the tubular portion 110 is expanded. The engaging portion 120 has an intersection portion 121 where the wires W intersect when viewed in the radial direction of the tubular portion 110, and an annular portion 122 that is annular with the intersection portion 121 as a base point.

[0048] As described above, the stent 10 of this embodiment includes the locking portions 120 that protrude outward from the tubular portion 110 when the tubular portion 110 is expanded, and therefore the anchor effect of the locking portions 120 can prevent the stent 10 from shifting position after placement. Furthermore, because the locking portions 120 have the intersection portions 121 and the annular portions 122, the locking portions 120 are relatively narrow at the intersection portions 121. Therefore, even with a stent 10 that includes the locking portions 120, the diameter of the stent 10 can be easily reduced, improving the ease of mounting the stent 10 on a delivery system.

[0049] Furthermore, the stent 10 of this embodiment includes a plurality of locking portions 120 that are located at different positions along the central axis Ax of the tubular portion 110. In the circumferential direction D1 of the tubular portion 110, the position of one of the plurality of locking portions 120 is different from the position of another of the plurality of locking portions 120. Therefore, according to the stent 10 of this embodiment, the plurality of locking portions 120 that are arranged in a balanced manner along the axial direction and the circumferential direction D1 of the tubular portion 110 can provide a balanced anchor effect, and can effectively prevent the stent 10 from shifting position after placement.

[0050] The stent 10 of this embodiment further includes a resin cover 200 that covers at least a portion of the tubular portion 110. The cover 200 is also disposed in the region 123 surrounded by the annular portion 122 of the engaging portion 120. Therefore, according to the stent 10 of this embodiment, it is possible to more effectively alleviate the stress concentration on the body wall 21 caused by the engaging portion 120, and more effectively suppress the occurrence of bleeding or perforation in the body wall 21. Furthermore, the cover 200 can prevent tumors, granulation tissue, etc. from entering the engaging portion 120, making the removal operation easier.

[0051] B. Second Embodiment: Figure 7 is a development view of the main body 100a constituting the stent 10 in the second embodiment. In the following, among the configuration of the main body 100a of the stent 10 in the second embodiment, the same configuration as that of the main body 100 of the stent 10 in the first embodiment described above will be denoted by the same reference numerals and the description thereof will be omitted as appropriate.

[0052] The main body 100a of the stent 10 of the second embodiment differs from that of the first embodiment in the configuration of the locking portion 120. Specifically, in the second embodiment, the annular portion 122 of the locking portion 120 has an asymmetric shape with respect to an imaginary straight line VL3 connecting the intersection 121 and a portion P3 of the wire W constituting the annular portion 122 that is farthest from the intersection 121. That is, with the imaginary straight line VL3 as the center, the width D2 on one side (the right side in FIG. 7 ) is greater than the width D1 on the other side (the left side in FIG. 7 ).

[0053] In the stent 10 of this embodiment, the annular portions 122 of the engaging portion 120 are configured so that their widths in the left-right direction (width D1 and width D2) are different from each other, centered on the position of the intersection 121. This allows the anchor effect of the engaging portion 120 to be set to an appropriate size that is neither too large nor too small, effectively suppressing bleeding or perforation in the body wall 21 due to contact with the engaging portion 120, while also effectively suppressing displacement of the stent 10 after placement.

[0054] C. Third Embodiment: Figure 8 is a development view of the main body portion 100b constituting the stent 10 in a third embodiment. In the following, among the configuration of the main body portion 100b of the stent 10 of the third embodiment, the same configuration as that of the main body portion 100 of the stent 10 of the first embodiment described above will be denoted by the same reference numerals and description thereof will be omitted as appropriate.

[0055] The main body 100b of the stent 10 of the third embodiment differs from that of the first embodiment in the configuration of the locking portion 120. Specifically, in the third embodiment, the locking portion 120 is formed by twisting the wire W twice. Therefore, the locking portion 120 has two combinations of an intersection portion 121 and an annular portion 122. That is, the locking portion 120 has a combination of a first intersection portion 121A and a first annular portion 122A that has the first intersection portion 121A as its base point, and a combination of a second intersection portion 121B and a second annular portion 122B that has the second intersection portion 121B as its base point.

[0056] In the third embodiment, the two combinations of the intersection 121 and the annular portion 122 have different directions of formation of the annular portion 122 relative to the intersection 121. That is, the angle θ1 formed by the imaginary line VL1 connecting the first intersection 121A and the portion P1 of the wire W of the first annular portion 122A farthest from the intersection 121A and the imaginary line VL2 connecting the second intersection 121B and the portion P2 of the wire W of the second annular portion 122B farthest from the intersection 121B is greater than 0 degrees and less than 180 degrees. The angle θ1 may be greater than 10 degrees and less than 180 degrees, or greater than 60 degrees and less than 120 degrees. Note that the angle θ1 refers to the angle extending along the length of the tubular portion 110 from the intersection point of the imaginary line VL1 and the imaginary line VL2.

[0057] In the stent 10 of this embodiment, the engaging portion 120 has two combinations of the intersection portion 121 and the annular portion 122, and therefore one engaging portion 120 comes into contact with the body wall 21 at two locations. This effectively reduces the stress concentration on the body wall 21 caused by the engaging portion 120, effectively suppressing bleeding and perforation in the body wall 21, and effectively suppressing displacement of the stent 10 after placement.

[0058] Furthermore, in the stent 10 of this embodiment, the angle θ1 is greater than 0 degrees and less than 180 degrees. Therefore, compared to configurations in which the two combinations of intersections 121 and annular portions 122 are formed in the same direction relative to the intersections 121, the diameter of the stent 10 including the locking portions 120 can be reduced more easily, and the stent 10 can be more easily mounted on a delivery system.

[0059] D. Fourth Embodiment: Figure 9 is a development view of the main body portion 100c constituting the stent 10 in the fourth embodiment. In the following, among the configuration of the main body portion 100c of the stent 10 of the fourth embodiment, the same configuration as that of the main body portion 100 of the stent 10 of the first embodiment described above will be denoted by the same reference numerals and description thereof will be omitted as appropriate.

[0060] The main body 100c of the stent 10 of the fourth embodiment differs from that of the first embodiment in the configuration of the locking portion 120. Specifically, in the fourth embodiment, the locking portion 120 is formed by twisting and doubling the wire W. Therefore, the annular portion 122 of the locking portion 120 is formed in a double annular shape with the intersection 121 as the base point. In this embodiment, the annular portion 122 is formed in a double annular shape with the circumferential length of the wire W being the same.

[0061] In the stent 10 of this embodiment, the annular portion 122 of the engaging portion 120 is formed into a double annular shape with the intersection portion 121 as the base point, thereby increasing the anchor effect of the engaging portion 120 and effectively suppressing displacement of the stent 10 after placement.

[0062] E. Fifth Embodiment: Figure 10 is a development view of a main body portion 100d constituting a stent 10 in a fifth embodiment. In the following, among the configuration of the main body portion 100d of the stent 10 of the fifth embodiment, the same configuration as that of the main body portion 100 of the stent 10 of the first embodiment described above will be denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0063] The main body 100d of the stent 10 of the fifth embodiment differs from that of the first embodiment in the configuration of the locking portion 120. Specifically, in the fifth embodiment, the locking portion 120 is formed by twisting and doubling the wire W. Therefore, the annular portion 122 of the locking portion 120 is formed into a double annular shape with the intersection portion 121 as the base point. In this embodiment, the annular portion 122 is formed into a double annular shape with the circumferential lengths of the wire W being different from each other.

[0064] In the stent 10 of this embodiment, the annular portion 122 of the locking portion 120 is formed into a double annular shape with the intersecting portion 121 as the base point, which increases the anchoring effect of the locking portion 120 and effectively prevents displacement of the stent 10 after placement. Furthermore, in the stent 10 of this embodiment, the annular portion 122 is formed into a double annular shape with wire W having different circumferential lengths, which makes it possible to easily and reliably form the cover 200 in the region 123 surrounded by the annular portion 122, and thereby makes it possible to reduce the thickness of the cover 200 formed in the region 123, for example.

[0065] F. Modifications: The technology disclosed in this specification is not limited to the above-described embodiment, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0066] The configuration of the stent 10 in the above embodiment is merely an example and can be modified in various ways. For example, the shape of the annular portion 122 of the locking portion 120 is not limited to a substantially elliptical shape, but may be a substantially polygonal shape. Furthermore, the positions and number of the locking portions 120 formed on the tubular portion 110 can be changed as desired. Furthermore, the main body portion 100 does not need to have the protrusions 130. Furthermore, when the stent 10 has multiple locking portions 120, these locking portions 120 may have the same shape or different shapes.

[0067] In the second embodiment, the annular portion 122 of the locking portion 120 has a shape in which the width W2 in the right direction about the position of the intersection 121 is larger than the width W1 in the left direction when viewed in the radial direction of the tubular portion 110. However, the width W1 in the left direction may be larger than the width W2 in the right direction. Furthermore, the stent 10 may include both an locking portion 120 having an annular portion 122 with a shape in which the width W2 in the right direction is larger than the width W1 in the left direction, and an locking portion 120 having an annular portion 122 with a shape in which the width W1 in the left direction is larger than the width W2 in the right direction.

[0068] In the third embodiment, the locking portion 120 has two combinations of the intersecting portion 121 and the annular portion 122, but the locking portion 120 may have three or more such combinations. Also, in the third embodiment, the angle θ1 may be 0 degrees or 180 degrees.

[0069] In the fourth and fifth embodiments, the annular portion 122 of the locking portion 120 is formed in a double annular shape with the intersecting portion 121 as the base point, but the annular portion 122 may be formed in a triple or more annular shape with the intersecting portion 121 as the base point. In this specification, "multiple" means double or more.

[0070] The manufacturing method of the stent 10 in the above embodiment is merely an example and can be modified in various ways. For example, in the above embodiment, when the main body portion 100 is produced by hook knitting, six V-shaped portions are knitted in the circumferential direction D1, but the number of V-shaped portions aligned in the circumferential direction D1 may be five or less, or seven or more. Furthermore, the technology disclosed in this specification is not limited to stents produced by hook knitting, but can also be applied to stents produced by other knitting methods (e.g., cross knitting). Furthermore, the knitting method of the main body portion 100 does not need to be entirely hook knitting, and may be a knitting method that includes hook knitting in part.

[0071] In the above embodiment, the stent 10 is a covered stent having a cover 200, but the technology disclosed in this specification is similarly applicable to an uncovered stent that does not have a cover 200.

[0072] 10: Stent 20: Biological lumen 21: Body wall 100: Main body portion 101: Tangled portion 102: Intersecting portion 110: Cylindrical portion 114: Crimped portion 120: Locking portion 120l: Lower locking portion 120u: Upper locking portion 121: Intersecting portion 121A: First intersecting portion 121B: Second intersecting portion 122: Annular portion 122A: First annular portion 122B: Second annular portion 123: Region 130: Protruding portion 200: Cover Ax: Central axis CE: Cell D1: Circumferential direction JG: Jig PN: Pin ST: Starting point W: Wire

Claims

1. A stent comprising: a tubular portion formed by weaving wires and configured to be expandable; and a locking portion formed from the wires and protruding outward from the tubular portion when the tubular portion is expanded, wherein the locking portion has an intersection portion where the wires intersect when viewed in the radial direction of the tubular portion, and a ring-shaped portion having an annular shape based on the intersection portion.

2. A stent according to claim 1, wherein the engagement portion has a plurality of combinations of the intersection portion and the annular portion.

3. A stent as described in claim 2, wherein an angle θ1 between an imaginary line connecting the intersection in one of the combinations and the portion of the wires constituting the annular portion that is the furthest from the intersection and an imaginary line connecting the intersection in another of the combinations and the portion of the wires constituting the annular portion that is the furthest from the intersection is greater than 0 degrees and less than 180 degrees.

4. A stent as described in any one of claims 1 to 3, wherein the annular portion has an asymmetric shape with respect to an axis of a virtual straight line connecting the intersection and the portion of the wire constituting the annular portion that is farthest from the intersection.

5. A stent according to any one of claims 1 to 4, wherein the annular portion is formed into multiple annular portions with the intersection portion as a base point.

6. A stent as claimed in claim 5, wherein said annular portion is formed into multiple annular portions having different circumferential lengths, with said intersection portion as a base point.

7. A stent as described in any one of claims 1 to 6, comprising a plurality of locking portions whose positions along the axial direction of the tubular portion are different from each other, and in the circumferential direction of the tubular portion, the position of one of the plurality of locking portions is different from the position of another of the plurality of locking portions.

8. A stent as claimed in any one of claims 1 to 7, further comprising a resin cover covering at least a portion of said tubular portion, said cover also being disposed in the area surrounded by said annular portion.

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