stents

Abstract

Provided is a stent which has, at an end part thereof, high conformability to a biological lumen and which can be appropriately indwelled also in a biological lumen having a complex shape.　A duodenal stent (1) is a tubular stent which is indwelled in a duodenum (D) (biological lumen), said duodenal stent (1) comprising a first circumferential surface part (20A) (movable part 2) which is formed such that the first circumferential surface part (20A) can be expanded and contracted in the radial direction that is substantially perpendicular to the axial direction (AX) and in which a part that is located more toward an extreme end than a central part in the axial direction (AX) is formed such that at least a portion of the part can be displaced in at least one of the axial direction, the radial direction, and the circumferential direction relative to the other portion.

Description

[Technical Field]

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

[0002] Conventionally, stents have been known that are placed in narrowed or obstructed areas in biological lumens such as blood vessels, esophagus, bile duct, trachea, and ureter, and that expand the diameter of the lesion area to maintain the patency of the biological lumen (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4651943 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a biological lumen has a complex shape, such as being curved or flattened or having protrusions, stress is likely to be applied to the biological lumen during stent placement. Although the flexibility of the biological lumen corrects the lumen shape and reduces the stress to some extent, localized stress concentration can potentially damage the biological lumen. In particular, a stent that is formed into a straight cylindrical shape over its entire length, such as the stent disclosed in Patent Document 1, is difficult to conform to a curved biological lumen. Because axial force (straightening force) strongly presses a portion of the circumferential surface at the end of the stent against the lumen wall, the risk of perforation increases during long-term placement. Furthermore, for example, if the end of the stent is expanded to prevent deviation due to pulsatile flow or lumen movement, the expansion force is greater than when the entire stent is formed into a straight cylindrical shape, and the load on the biological lumen is also greater.

[0005] An object of the present invention is to provide a stent that has high conformability to the biological lumen at the end portions of the stent and can be appropriately placed even in biological lumens with complex shapes. [Means for solving the problem]

[0006] The stent according to the present invention comprises: A cylindrical stent to be placed in a biological lumen, Can be expanded and contracted in the radial direction, which is roughly perpendicular to the axial direction a cylindrical first stent portion; , a second stent portion that is different from the first stent portion in at least one of the shape and the radial expansion force, each of the first stent section and the second stent section is formed by weaving a wire rod that extends spirally while being folded back in a zigzag shape into a diamond-shaped wire mesh shape such that a convex peak portion on one end side in the axial direction and a convex valley portion on the other end side in the axial direction intermesh with each other; the second stent portion is formed by a first circumferential surface portion that is disposed on the distal side of the central portion in the axial direction and is formed so as not to be continuous in the circumferential direction, a second circumferential surface portion that is provided on the first stent portion side of the first circumferential surface portion and is formed so as to be connected in the circumferential direction, and the first circumferential surface portion; At least one portion is axially, radially, and radially inclined relative to the other portion. The aforementioned A movable portion formed so as to be displaceable in at least one direction among the circumferential directions. and The first circumferential surface portion has a plurality of skeletal portions arranged circumferentially apart, and the circumferential lengths of the plurality of skeletal portions increase toward the tip side, which is opposite the second circumferential surface portion. [Effects of the Invention]

[0007] According to the present invention, the ability of the end portion of the stent to conform to the biological lumen is improved, and the stent can be placed appropriately even in a biological lumen having a complex shape. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the appearance of a duodenal stent according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of an indwelling mode of the duodenal stent according to the first embodiment. [Figure 3] FIG. 3 is a schematic diagram of a second stent portion of the duodenal stent according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a modified example of the second stent section. [Figure 5] FIG. 5 is a diagram showing the appearance of a duodenal stent according to the second embodiment. [Figure 6]FIG. 6 is a diagram showing an example of an indwelling mode of the duodenal stent according to the second embodiment. [Figure 7] 7A and 7B are schematic diagrams showing an example of a constricted portion in a duodenal stent according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, as an example of the present invention, duodenal stents 1 and 2 that are placed in the duodenum D to treat obstruction (stenosis) by radially expanding a lesion in the duodenum D outward will be described.

[0010] [First embodiment] Fig. 1 is a diagram showing the appearance of a duodenal stent 1 according to a first embodiment. Fig. 2 is a diagram showing an indwelling state of the duodenal stent 1. Fig. 3 is a schematic diagram of a second stent portion 20.

[0011] The duodenal stent 1 is placed in the duodenum D to expand the lumen and define a flow path for digestive matter (fluid) (see FIG. 2). The duodenal stent 1 is placed, for example, so as to straddle the boundary between the duodenal bulb D1 and the descending duodenum D2. As shown in Fig. 1, the duodenal stent 1 is a so-called bare stent, which is composed only of a skeleton. The duodenal stent 1 has a first stent section 10 and a second stent section 20 connected to the first stent section 10. In Fig. 1, the boundary between the first stent section 10 and the second stent section 20 is indicated by a dashed line. In the following description, the second stent section 20 side in the axial direction AX will be referred to as "one end side" and the opposite side as "the other end side".

[0012] The duodenal stent 1 is provided with a movable section 2 at one end portion closer to the tip than the central portion in the axial direction AX, the movable section 2 being formed so that one portion can be displaced relative to the other portion in at least one direction among the axial direction AX, the radial direction perpendicular to the axial direction AX, and the circumferential direction about the axis. In other words, the movable section 2 has a structure that can easily follow the shape of the duodenum D. In this embodiment, the movable section 2 is provided in the second stent section 20. Here, the "portion closer to the distal end than the central portion" is the portion that is strongly pressed against the biological lumen wall by the axial force (straightening force) of the duodenal stent 1.

[0013] The first stent section 10 has a cylindrical shape extending straight along the axial direction AX and is radially expandable and contractible. The first stent section 10 is disposed, for example, in the descending duodenum D2 downstream of the duodenal bulb D1 in the flow direction of digestive matter, and is formed long so that the other end is located downstream of the papilla of Vater VP. The first stent section 10 is formed, for example, by a tubular framework 11 formed by braiding wires into a tubular shape so that elongation in the axial direction AX is restricted.

[0014] The second stent section 20 is bent relative to the descending duodenum D2 and placed in the duodenal bulb D1, which has a different shape from the descending duodenum D2. The second stent section 20 is connected to one end of the first stent section 10 and has a flared shape that is inclined so as to expand in diameter toward the distal end in the axial direction AX. In other words, the second stent section 20 has a different shape and radial expansion force from the first stent section 10.

[0015] The second stent section 20 is located closer to the end than to the center in the axial direction AX. The second stent section 20 has a first circumferential surface section 20A and a second circumferential surface section 20B, and the first circumferential surface section 20A functions as a movable section 2 that can easily follow the biological lumen.

[0016] The second circumferential surface portion 20B is continuous with one end of the first stent portion 10. The second circumferential surface portion 20B is a portion consisting of one crown-shaped skeleton 25 (hereinafter referred to as "crown skeleton 25"). In other words, the second circumferential surface portion 20B is formed continuously in the circumferential direction. Furthermore, the first circumferential surface portion 20A is connected to the end (tip) of the second circumferential surface portion 20B opposite to the first stent portion 10.

[0017] The first peripheral surface portion 20A is a portion in which four petal-shaped skeletons 21-24 (hereinafter referred to as "petal skeletons 21-24") are arranged at intervals in the circumferential direction so as to form a flared shape. In other words, the first peripheral surface portion 20A is formed so that they are not continuous in the circumferential direction. A gap is provided between adjacent skeletons among the petal skeletons 21-24.

[0018] It should be noted that the number of petal skeletons 21 to 24 is not limited to four, as long as there is more than one. Increasing the number of petal skeletons 21 to 24 increases the degree of freedom of the first circumferential surface portion 20A, making it easier to follow the biological lumen, but it also reduces the expandability and shape stability when returning from the contracted state to the expanded state, which may make it easier for the duodenal stent 1 to slip out of the duodenum D. Therefore, the number of petal skeletons 21 to 24 is set appropriately taking these factors into consideration. Furthermore, it is preferable that the size of the gap between adjacent ones of the petal skeletons 21 to 24 be set in consideration of the magnitude of the displacement of the petal skeletons 21 to 24 in the circumferential direction.

[0019] Since the first circumferential surface portion 20A is formed by separated petal skeletons 21 to 24, the expansion force and shape stability are reduced compared to when the first circumferential surface portion 20A is formed by connecting the petal skeletons 21 to 24 in a tubular shape. In this embodiment, the second circumferential surface portion 20B is provided at the end of the first stent portion 10 side of the first circumferential surface portion 20A, and by forming a form in which one end is connected in the circumferential direction, the reduction in the expansion force and shape stability of the first circumferential surface portion 20A is suppressed.

[0020] 4, the petal skeletons 21-24 forming the first circumferential surface portion 20A may be connected in the circumferential direction using a connecting member 26 such as a crimping member to the extent that followability is not impaired. Note that the second stent portion 20 may be formed only with the first circumferential surface portion 20A without being provided with the second circumferential surface portion 20B, and the first circumferential surface portion 20A may be directly connected to the first stent portion 10.

[0021] The petal skeletons 21 to 24 of the first circumferential surface portion 20A and the cap skeleton 25 of the second circumferential surface portion 20B are formed by braiding wires, for example, in the same manner as the tubular skeleton 11 of the first stent portion 10.

[0022] The tubular skeleton 11 of the first stent section 10, and the petal skeletons 21 to 24 and crown skeleton 25 of the second stent section 20 are formed by weaving four wire rods that extend spirally while being folded back in a zigzag (Z-shape) at a predetermined pitch into a diamond-shaped wire mesh (fence-like) shape so that the bent portions (one peak portion (the convex portion on one axial end side) and the other valley portion (the convex portion on the other axial end side)) interlock with each other.

[0023] The tubular skeleton 11, petal skeletons 21 to 24 and crown skeleton 25 may not be diamond-shaped wire mesh, but may be constructed by bending one or more wire rods so that peaks and valleys are alternately formed and then spirally wound and woven in the axial direction of each wire rod.

[0024] The tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25 have so-called self-expandability, that is, they memorize the shape of their expanded state, and expand radially outward upon release from a sheath (not shown). That is, the first stent section 10 and the second stent section 20 are configured to be deformable from a contracted state in which they are folded radially inward to an expanded state in which they expand radially outward to define a tubular flow path.

[0025] Examples of materials for the wires forming the tubular skeleton 11, the petal skeletons 21 to 24, and the cap skeleton 25 include known metals or metal alloys, such as stainless steel, Ni-Ti alloy (nitinol), and titanium alloy. An alloy material having radiopaque properties may also be used. In this case, the position of the duodenal stent 1 can be confirmed from outside the body. The tubular skeleton 11, the petal skeletons 21 to 24, and the cap skeleton 25 may also be formed from materials other than metals (e.g., ceramics, resins, etc.).

[0026] The material, wire diameter (cross-sectional area), number of circumferential folds and fold shape (number and shape of bent portions), and mesh size (amount of skeletal structure per unit length) of the wires forming the tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25 are appropriately selected based on the expansive force and flexibility of the first stent section 10 and the second stent section 20 required for the biological lumen in which they are to be placed. Here, flexibility refers to the ease with which the first stent section 10 and the second stent section 20 bend, and is particularly determined by their axial bending rigidity. That is, the first stent section 10 and the second stent section 20 have high flexibility when their axial bending rigidity is appropriately low and they have the property of conforming to the shape of the biological lumen or sheath without kinking within the biological lumen or sheath.

[0027] As shown in Figure 3, in the second stent section 20, the petal skeletons 21-24 each have a generally fan-shaped configuration in the unfolded state, with the circumferential length increasing toward the tip. The petal skeletons 21-24 are connected to the end (tip) of the cap skeleton 25 opposite the first stent section 10 so that they are adjacent to each other in a curved state. This forms the second stent section 20 in a flared shape. The petal skeletons 21-24 and the cap skeleton 25 may be formed from separate wires and then connected using a crimping member or the like, or may be formed integrally from the same wire.

[0028] Unlike a typical flare shape, the second stent section 20 has petal skeletons 21 to 24 arranged separately in the circumferential direction, and therefore each can be independently displaced radially and in the axial direction AX, with the connection to the crown skeleton 25 as a fixed end. Furthermore, since there is a gap between adjacent ones of the petal skeletons 21 to 24, each can be displaced independently in the circumferential direction. In this way, one petal skeleton (for example, petal skeleton 21) is formed as one part, and another petal skeleton (for example, petal skeleton 22) is formed as another part, so that one petal skeleton can be displaced in the axial direction AX, the longitudinal direction, and the circumferential direction relative to the other petal skeletons. As a result, the first peripheral surface portion 20A consisting of petal skeletons 21 to 24 functions as a movable portion 2 that can easily follow the biological lumen.

[0029] When the second stent section 20 is released from the sheath, the petal skeletons 21 to 24 attempt to restore their expanded state. At this time, the petal skeletons 21 to 24 can independently displace in the axial, radial, and circumferential directions, and even if the placement site is curved or has protrusions, they can follow the shape of the curved or bulged area and adhere appropriately.

[0030] In this way, the duodenal stent 1 is a tubular stent that is placed in the duodenum D (biological lumen) and is formed to be expandable and contractable in a radial direction that is approximately perpendicular to the axial direction AX, and the portion distal to the center of the axial direction AX has a movable portion 2 formed so that at least one portion can be displaced relative to the other portions in at least one of the axial direction AX, the radial direction, and the circumferential direction. Specifically, the duodenal stent 1 comprises a cylindrical first stent section 10 that is radially expandable and contractible, and a second stent section 20 that differs from the first stent section 10 in at least one of its shape and radial expansion force. Of the first stent section 10 and the second stent section 20, the second stent section 20, which is positioned distally of the center in the axial direction AX, has a movable section 2. According to the duodenal stent 1, the movable portion 2 is formed so as to be displaceable in the axial direction AX, the radial direction, and the circumferential direction, and the portion distal to the center in the axial direction AX can be structured with a high degree of freedom, making it easier to follow the shape of the duodenum D having the duodenal bulb D1. This improves adhesion to the duodenal wall when the duodenal stent 1 is placed, allowing the duodenal stent 1 to be placed appropriately even in the duodenum D having a complex shape, and preventing displacement of the duodenal stent 1. Furthermore, the portion of the duodenal stent 1 distal to the center in the axial direction AX is no longer pressed strongly against the duodenal wall, reducing the load on the duodenum D.

[0031] Furthermore, in the duodenal stent 1, the second stent portion 20 of the first stent portion 10 and the second stent portion 20 is positioned closer to the tip than the center in the axial direction AX, and the movable portion 2 is formed by the first circumferential surface portion 20A of the circumferential surface portions 20A, 20B of the second stent portion 20, which is formed so as not to be continuous in the circumferential direction. This allows the first circumferential surface portion 20A, that is, the petal skeletons 21 to 24 arranged at intervals in the circumferential direction, to be displaced independently, thereby improving the adhesion to the duodenal wall.

[0032] The circumferential surface of the second stent section 20 is provided with a second circumferential surface section 20B that is connected in the circumferential direction. As a result, the reduction in the expansive force caused by the first circumferential surface portion 20A being separated in the circumferential direction can be compensated for by the second circumferential surface portion 20B.

[0033] The second stent section 20 is provided on the distal end side in the axial direction AX, and has a flared shape that is inclined so that the outer diameter expands toward the distal end side in the axial direction AX. As a result, even if the second stent portion 20 is configured to have a flared shape in order to increase its expansion force, by forming the first circumferential surface portion 20A so that it is not continuous in the circumferential direction, the load on the duodenum D can be reduced, and the risk of perforation when the duodenal stent 1 is left in place for a long period of time can be reduced.

[0034] [Second embodiment] Fig. 5 is a diagram showing the appearance of a duodenal stent 1A according to the second embodiment. Fig. 6 is a diagram showing the duodenal stent 1A in an indwelling state. In the duodenal stent 1A, components that are the same as or correspond to those of the duodenal stent 1 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

[0035] The duodenal stent 1A is placed, for example, so as to straddle the pylorus P, which is the boundary between the stomach S and the duodenal bulb D1 (see FIG. 6). Specifically, the duodenal stent 1A is placed so that the constricted portion 3 formed at the boundary between the first stent portion 10 and the second stent portion 20 is positioned at the pylorus P.

[0036] In the second embodiment, the first stent section 10 has a straight section 10A extending straight along the axial direction AX and a tapered section 10B connected to the straight section 10A and tapering toward the second stent section 20. The tapered section 10B is inclined so that its outer diameter increases toward the base end in the axial direction AX. The first stent section 10 is disposed, for example, from the duodenal bulb D1 to the descending duodenum D2 in the flow direction of digestive matter. In particular, the tapered section 10B is disposed near the pylorus P in the duodenal bulb D1.

[0037] The second stent section 20 is connected to the tip side of the tapered section 10B in the axial direction AX, and has a flared shape that slopes so that the outer diameter increases toward the tip side. The second stent section 20 is placed, for example, near the pylorus P in the stomach S, which has a shape different from that of the duodenal bulb D1. In the second embodiment, the second stent section 20 is formed only by a first circumferential surface section 20A consisting of petal skeletons 21-24, and the first circumferential surface section 20A is connected to the tapered section 10B of the first stent section 10. The tapered portion 10B of the first stent portion 10 and the flared first circumferential surface portion 20A of the second stent portion 20 form a constricted portion 3. The shape of the constricted portion 3, i.e., the inclination angles of the tapered portion 10B and the first circumferential surface portion 20A, are set according to the shape of the pylorus P.

[0038] As in the first embodiment, the second stent section 20 has a second circumferential surface section 20B consisting of a cap skeleton 25 connected to the first circumferential surface section 20A (petal skeletons 21 to 24), and the second circumferential surface section 20B may be connected to the tapered section 10B of the first stent section 10. In this case, the tapered section 10B and the second circumferential surface section 20B form the constricted section 3.

[0039] In duodenal stent 1A, a tapered portion 10B is provided in first stent portion 10, and compared to duodenal stent 1 according to the first embodiment, the boundary between first stent portion 10 and second stent portion 20 is more tightly constricted, and the diameter of constricted portion 3 is smaller. For example, an appropriate tapered shape can be formed by changing the size or number of meshes of tubular framework 11 of tapered portion 10B.

[0040] The pylorus P, which is the connecting portion between the duodenum D and the stomach S, has a smaller diameter than the tubular diameter on the stomach S side near the pylorus P and the tubular diameter on the duodenum D side, has a sharply curved drum shape, and is normally closed. In addition, the pylorus P can also be said to have a steep, approximately hyperbolic shape in a cross section along the flow direction of digested matter.

[0041] The first stent section 10 is provided with a tapered section 10B, and the constricted section 3 located at the pylorus P is formed steeply, thereby enabling a strong engagement at the pylorus P. That is, the engagement of the second stent section 20 with the pylorus P prevents the duodenal stent 1A from shifting toward the duodenum D, and the engagement of the tapered section 10B of the first stent section 10 with the pylorus P also prevents the duodenal stent 1A from shifting toward the stomach S. Furthermore, the flared petal skeletons 21-24 open more easily, making them more likely to come into contact with the stomach wall near the pylorus P, and the engagement of the petal skeletons 21-24 effectively prevents the duodenal stent 1A from shifting.

[0042] Furthermore, the radial expansion force of the tapered portion 10B is preferably smaller than that of the straight portion 10A. Similarly, the radial expansion force of the second stent portion 20 near the constricted portion 3 is preferably smaller than that of the distal end portion away from the constricted portion 3. The tapered portion 10B and the second stent portion 20 may be configured, for example, so that their radial expansion force gradually decreases toward the constricted portion 3. In this case, the constricted portion 3 can easily expand and contract, making it easier to follow the opening and closing of the pylorus P and reducing the load on the pylorus P. The expansion force of the tapered portion 10B and the second stent portion 20 can be appropriately adjusted, for example, by changing the mesh size and number of the tubular skeleton 11 and the petal skeletons 21-24. Note that, in order to reduce the load on the pylorus P, it is sufficient that the expansion force of at least one of the tapered portion 10B and the second stent portion 20 is controlled as described above.

[0043] 7A and 7B are schematic diagrams showing an example of the constricted portion 3 of the duodenal stent 1A. 7A, a constricted portion 3 is formed at the connection portion (the engagement portion between the bent portions) between the tubular skeleton 11 of the first stent portion 10 (tapered portion 10B) and the petal skeletons 21 to 24 of the second stent portion 20. In this case, the constricted portion 3 is easily deformed, which makes it easier to reduce the load on the pylorus portion P.

[0044] 7B, constricted portions 3 are formed in the straight line portions of petal skeletons 21 to 24 of second stent section 20. In this case, constricted portions 3 are less likely to deform, making it easier to prevent displacement at pylorus P.

[0045] As described above, the duodenal stent 1A has the following characteristic structure in addition to the structure of the duodenal stent 1 according to the first embodiment. That is, in the duodenal stent 1A, the first stent portion 10 has a tapered portion 10B that is inclined so that the outer diameter increases toward the base end in the axial direction AX, and the second stent portion 20 is positioned closer to the tip than the central portion in the axial direction, and the base end side of the second stent portion 20 is connected to the tip side in the axial direction AX of the tapered portion 10B, and has a flared shape that is inclined so that the outer diameter increases toward the tip side. As a result, when duodenal stent 1A is placed in a small-diameter portion such as pylorus P, constricted portion 3, which is the boundary between tapered portion 10B and second stent portion 20, catches on the duct wall near pylorus P and is physically locked in place, making it easier for second stent portion 20 to follow the shape of the periphery of pylorus P due to movable portion 2, thereby improving adhesion to the stomach wall. As a result, the placement of duodenal stent 1A is significantly improved.

[0046] Furthermore, in the duodenal stent 1A, the radial expansion force of at least one of the tapered portion 10B and the second stent portion 20 decreases toward the constricted portion 3, which is the boundary between the tapered portion 10B and the second stent portion 20. This allows the constricted portion 3 to more easily follow the movement of the small diameter portion, such as the opening and closing of the pylorus P, thereby reducing the load on the small diameter portion.

[0047] The invention made by the inventor has been specifically described above based on an embodiment, but the present invention is not limited to the above embodiment and can be modified within the scope of the gist thereof.

[0048] For example, in the above embodiment, a configuration in which one petal skeleton (e.g., petal skeleton 21) is formed so as to be displaceable in the axial direction AX, the longitudinal direction, and the circumferential direction relative to another petal skeleton (e.g., petal skeleton 22) has been exemplified, but this is merely an example and is not limiting. That is, it is sufficient that one petal skeleton is formed so as to be displaceable in at least one direction among the axial direction AX, the longitudinal direction, and the circumferential direction relative to another petal skeleton. Furthermore, if the entire second stent section 20 is made a movable section, it is sufficient that the second stent section 20 is formed so as to be displaceable in at least one direction among the axial direction AX, the longitudinal direction, and the circumferential direction relative to another section (e.g., first stent section 10).

[0049] Furthermore, for example, although the second stent section 20 has a flared shape in the embodiment, it may be formed in a straight cylindrical shape. Furthermore, in the second stent section 20, the second circumferential surface section 20B for supplementing the expansion force of the first circumferential surface section 20A may be provided at an end portion on one end side of the first circumferential surface section 20A, or may be provided so as to sandwich the first circumferential surface section 20A in the axial direction.

[0050] In the embodiment, the case where a highly compliant structure of the movable part 2 is realized by using a plurality of petal skeletons 21 to 24 has been described, but the structure of the movable part 2 is not limited to this. For example, the compliant property can be improved by changing the diameter, material, mesh size, etc. of the wire material that forms the movable part 2. In addition, in the embodiment, the movable portion 2 is described as being provided in the second stent portion 20, but the movable portion 2 may be provided in the first stent portion 10, or may be provided in both the first stent portion 10 and the second stent portion 20.

[0051] Furthermore, although not shown, in the duodenal stents 1 and 1A, the first stent section 10 and the second stent section 20 may be provided with a coating so as to cover the tubular skeleton 11, the petal skeletons 21 to 24, and the cap skeleton 25. By providing the coating, it is possible to prevent the narrowed portion of the duodenum D from bulging inward of the tubular skeleton 11, the petal skeletons 21 to 24, and the cap skeleton 25, and it is possible to appropriately expand the narrowed portion.

[0052] Furthermore, the flare shape that slopes to increase in diameter toward the tip side may have any shape that slopes to increase in diameter overall, and the detailed shape is not particularly limited. For example, the flare shape may be an inverted cone shape that slopes linearly with a constant expansion rate, or a shape that slopes in a broken line with a varying expansion rate. Furthermore, the flare shape may be a curved slope, such as a hemispherical shape like a bowl with a gradually decreasing expansion rate toward the tip side, or a trumpet shape with a gradually increasing expansion rate toward the tip side. Furthermore, for example, the flare shape may be a shape that slopes to increase in diameter overall, and may partially narrow toward the tip side.

[0053] Examples of materials for forming the coating include silicone resin, fluororesin such as PTFE (polytetrafluoroethylene), and polyester resin such as polyethylene terephthalate. The configuration of the coating can be changed as appropriate. For example, the coatings may be arranged on the outer and inner surfaces of the skeletons so as to sandwich the tubular skeleton 11, the petal skeletons 21-24, and the cap skeleton 25, or may be arranged only on the outer surfaces of the tubular skeleton 11, the petal skeletons 21-24, and the cap skeleton 25. Furthermore, for example, the coating may be provided on either the first stent section 10 or the second stent section 20, or may be provided entirely or partially on each of them.

[0054] In addition, in the first embodiment, a configuration in which the second stent portion 20 of the duodenal stent 1 is placed in the duodenal bulb D1 has been described, but this is merely an example and is not limited to this, and the placement position (placement) of each component of the duodenal stent 1 can be changed as appropriate. For example, the duodenal stent 1 may be positioned so that at least the first circumferential surface portion 20A of the second stent portion 20 protrudes from the pylorus of the stomach. That is, by providing the movable portion 2 in a portion of the duodenal stent 1 closer to the distal end than the axial center, even in a digestive tract with a complex internal shape extending from the stomach to the duodenum D, the movable portion 2 can be positioned in the duodenal bulb D1 or the first circumferential surface portion 20A can protrude from the pylorus of the stomach, thereby improving the flexibility of the placement position of the duodenal stent 1. Furthermore, the second circumferential surface portion 20B of the second stent portion 20 may be positioned in the pylorus, which allows the first stent portion 10 to be positioned in a substantially straight line to the descending duodenum D2 without having to be aligned along the inner wall in accordance with the shape of the duodenal bulb D1, thereby improving the flexibility of the placement position of the duodenal stent 1.

[0055] The present invention is not limited to the duodenal stent described in the embodiment, but can also be applied to stents to be placed in body lumens having complex shapes, such as digestive lumens and blood vessels.

[0056] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0057] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2020-184540, filed on November 4, 2020, are incorporated herein by reference in their entirety. [Explanation of symbols]

[0058] 1. Duodenal stent (stent) 2 Moving parts 10 First stent section 20 Second stent section 20A 1st peripheral part 20B 2nd peripheral part

Claims

1. A cylindrical stent to be placed in a biological lumen, a cylindrical first stent portion that is expandable and contractable in a radial direction substantially perpendicular to the axial direction; a second stent portion that is different from the first stent portion in at least one of the shape and the radial expansion force, each of the first stent section and the second stent section is formed by weaving a wire rod that extends spirally while being folded back in a zigzag shape into a diamond-shaped wire mesh shape such that a convex peak portion on one end side in the axial direction and a convex valley portion on the other end side in the axial direction intermesh with each other; the second stent section has a first circumferential surface section that is disposed distally of a central section in the axial direction and is formed so as not to be continuous in the circumferential direction, a second circumferential surface section that is provided closer to the first stent section than the first circumferential surface section and is formed so as to be connected in the circumferential direction, and a movable section that is formed by the first circumferential surface section and at least one portion of which is formed so as to be displaceable relative to the other portions in at least one direction among the axial direction, the radial direction, and the circumferential direction, The first circumferential surface portion has a plurality of skeletal portions arranged at intervals in the circumferential direction, and the circumferential length of the plurality of skeletal portions increases toward the tip side, which is opposite the second circumferential surface portion.

2. the first stent portion has a tapered portion that is inclined so that the outer diameter increases toward the base end side in the axial direction, 2. The stent according to claim 1, wherein the second stent portion is positioned distally of the central portion in the axial direction, the base end side of the second stent portion is connected to the distal side of the tapered portion in the axial direction, and the stent has a flared shape that is inclined so that the outer diameter increases toward the distal side.

3. Further comprising a constricted portion formed at the boundary between the first stent portion and the second stent portion; 3. The stent according to claim 2, wherein the constricted portion is formed so as to be bent by an engagement portion between the wire material of the tapered portion of the first stent portion and the wire material of the second stent portion, or is formed by a straight portion of the wire material of the second stent portion.

4. The stent according to claim 2 , wherein at least one of the tapered section and the second stent section has an expansion force in the radial direction that decreases toward a boundary between the tapered section and the second stent section.

Images