Stent

Abstract

To provide a stent which can be easily indwelled on a branched part of a living body lumen, by a single manipulation.SOLUTION: A stent 1 comprises: a cylindrical first stent part 1A having a first skeleton part 11; and two cylindrical second stent parts 1B having second skeleton parts 12, 13. The first skeleton part and the two second skeleton parts are connected at a crotch part 1a where the two second stent parts are branched. Each of the first skeleton part and the two second skeleton parts is formed by bending a metal wire material so as to alternately form a crest part and a trough part in a circumferential direction surrounding respective axial directions of the skeleton parts and weaving so as to engage the crest parts and the trough parts in the axial direction, and can be self-expanded to an expanded state for defining a cylindrical channel by expansion from a shrunk state, in a radial direction substantially orthogonal to the axial directions. The first skeleton part and the two second skeleton parts have different wire diameters and heights of the crest parts, for achieving difference of expansion force in the radial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a stent to be placed in a biological lumen. [Background technology]

[0002] Conventionally, stents are known that are placed in narrowed or blocked areas in biological lumens such as blood vessels, esophagus, bile duct, trachea, and ureter to expand the diameter of the lesion and maintain the patency of the biological lumen. In stent graft placement, the stent may be branched and placed depending on the condition of the lesion. For example, for a lesion occurring near the hepatic portal, the common hepatic duct branches into the right hepatic duct and the left hepatic duct (bile ducts in the liver), so it is necessary to place stents in each of the common hepatic duct, the right hepatic duct, and the left hepatic duct.

[0003] In such a case, conventionally, a plurality of stents, such as a stent for a main lumen (e.g., common hepatic duct) and a stent for a branch lumen (e.g., right hepatic duct and left hepatic duct), are prepared, and one stent is inserted into the opening (e.g., mesh of the skeletal part) of one stent, and the stents are connected by partially overlapping each other (see, for example, Patent Document 1). For example, when placing a stent in a lesion site occurring near the porta hepatis, a stent placed in the other hepatic duct (e.g., left hepatic duct) is inserted and connected to a stent placed across from the common hepatic duct to one hepatic duct (e.g., right hepatic duct). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-138851 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of Patent Document 1 and the like, a placement system is required for each stent, and the procedure for placing the stent is complicated, which may lead to deformation or damage of the stent and blockage of the hepatic portal tract. In addition, the mesh of the stent may become entangled, making it difficult to remove after placement. Therefore, the practitioner performing the stent placement procedure is required to have a wealth of experience and high skill.

[0006] An object of the present invention is to provide a stent that can be easily placed in a bifurcated portion of a biological lumen in a single procedure. [Means for solving the problem]

[0007] The stent according to the present invention comprises: A stent to be placed in a biological lumen, A first stent portion having a cylindrical shape and a first framework portion is placed in a first lumen of the body lumen. and two cylindrical second stent portions each having a second framework portion and each of which is placed in a second lumen branched from the first lumen, The first framework portion and the two second framework portions are connected at a crotch portion where the two second stent portions branch off, Each of the first skeletal portion and the two second skeletal portions is formed by bending a metal wire so that peaks and valleys are alternately formed in a circumferential direction surrounding the axial direction, and the peaks and valleys are interwoven in the axial direction, and is configured to be self-expandable from a contracted state to an expanded state that defines a cylindrical flow path in a radial direction substantially perpendicular to the axial direction, The first skeletal portion and the two second skeletal portions have different wire diameters and peak heights, so that the radial expansion forces are different between the first skeletal portion and the two second skeletal portions. The first stent portion and the two second stent portions are formed integrally so as to be able to be placed in the first lumen and the second lumen. Effect of the Invention

[0008] According to the present invention, a stent can be easily placed in a branched portion of a biological lumen in a single procedure, and can also be easily removed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the appearance of a biliary stent according to a first embodiment. [Diagram 2] FIG. 2 shows a state in which a second stent portion is fitted to a first stent portion of a bile duct stent along the axial direction thereof. [Diagram 3] 3A and 3B are diagrams showing an example of a mode of placement of a bile duct stent. [Figure 4] FIG. 4 is a diagram showing the appearance of a biliary stent according to the second embodiment. [Diagram 5] 5A and 5B are diagrams showing modified examples of biliary stents. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [First embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, as an example of the present invention, a bile duct stent 1 is placed in the common hepatic duct H1, the right hepatic duct H2, and the left hepatic duct H3 to treat the obstruction (stenosis) by radially expanding a lesion (e.g., an obstruction or stenosis) in the hepatic hilum HP (see Figs. 3A and 3B) outward.

[0011] Fig. 1 is a diagram showing the appearance of a biliary stent 1 according to a first embodiment. Fig. 2 is a diagram showing a state in which second stent portions 1B and 1C are joined together along the axial direction of a first stent portion 1A of the biliary stent 1. Fig. 3 is a diagram showing an indwelling state of the biliary stent 1. Fig. 3B shows an enlarged view of the hepatic portal portion HP in Fig. 3A.

[0012] The biliary stent 1 is a so-called covered stent. The biliary stent 1 is divided into a first stent portion 1A and second stent portions 1B and 1C branching from the first stent portion 1A. As shown in Figures 3A and 3B, the first stent portion 1A is a portion to be placed in the common hepatic duct H1, and the second stent portions 1B and 1C are portions to be placed in the right hepatic duct H2 and the left hepatic duct H3.

[0013] The first stent portion 1A and the second stent portions 1B, 1C have a tubular shape that defines a bile flow path. In this embodiment, the second stent portions 1B, 1C have a smaller tube diameter than the first stent portion 1A and are connected to one end of the first stent portion 1A so as to branch into two. In other words, the bile duct stent 1 has a Y-shape as a whole. The angle of the bifurcation portion 1a where the second stent portions 1B, 1C branch is set according to the shape of the hepatic portal portion HP where the bile duct stent 1 is placed.

[0014] The first stent section 1A is provided with a first framework section 11. The second stent sections 1B and 1C are provided with second framework sections 12 and 13, respectively. The first skeleton portion 11 is configured, for example, by winding one or more metal wires in a spiral shape in the axial direction while bending the wires so that peaks and valleys are alternately formed. The second skeletal portions 12, 13 are configured, for example, in such a manner that a plurality of skeletons formed in an annular shape by bending a metal wire so that peaks and valleys are formed alternately are arranged at predetermined intervals in the axial direction. The first skeletal portion 11 and the second skeletal portions 12, 13 are configured to be self-expandable in a radial direction approximately perpendicular to their respective axial directions from a contracted state in which they contract inward to an expanded state in which they expand outward to define a cylindrical flow path.

[0015] The first skeletal portion 11 and the second skeletal portions 12, 13 may be connected to each other at the crotch portion 1a or may be separated from each other. The first skeletal portion 11 may be configured such that a plurality of skeletons formed in an annular shape by bending a metal wire so that peaks and valleys are alternately formed are arranged at a predetermined interval in the axial direction. The second skeletal portions 12 and 13 may be configured such that one or a plurality of metal wires are bent so that peaks and valleys are alternately formed and wound in a spiral shape in the axial direction. The first skeletal portion 11 and the second skeletal portions 12 and 13 may be configured, for example, such that the bent portions of the wires are interlocked with each other, thereby improving the flexibility of each skeletal portion and restricting deformation (stretching) in the axial direction. The first skeletal portion 11 and the second skeletal portions 12 and 13 may be configured such that a wire wound in a spiral shape in a clockwise direction and a wire wound in a counterclockwise direction (including a case where the same wire is folded back at an end) are interwoven with each other to form a mesh, thereby improving the linearity of each skeletal portion. Therefore, for example, the first skeletal portion 11 can be configured by interlocking and weaving the bent portions of wire material, and the second skeletal portions 12, 13 can be configured by crossing and weaving wire material with each other, thereby making it possible to create a bile duct stent 1 having a first skeletal portion 11 that has improved flexibility and restricts deformation in the axial direction, and second skeletal portions 12, 13 that have improved straightness.

[0016] The expansion force of the first skeletal portion 11 and the second skeletal portions 12, 13 can be controlled by the density (skeletal amount per unit length) in the axial direction of the wire material forming the first skeletal portion 11 and the second skeletal portion 12, 13. In this embodiment, the expansion force of the first skeletal portion 11 and the second skeletal portion 12, 13 is controlled by the height of the peaks. Specifically, the height of the peaks of the second skeletal portions 12, 13 is higher than the height of the peaks of the first skeletal portion 11, and the expansion force of the second skeletal portions 12, 13 is smaller than the expansion force of the first skeletal portion 11. The expansion forces of the second skeletal portions 12, 13 may be set to be different from each other, or may be set to be larger than the expansion force of the first skeletal portion 11.

[0017] In this way, the first skeletal portion 11 and the second skeletal portions 12, 13 have a tubular shape that can expand and contract in a radial direction that is approximately perpendicular to their respective axial directions, and the bile duct stent 1 presses the inner surfaces of the common hepatic duct H1, right hepatic duct H2, and left hepatic duct H3 with the outer surface of the bile duct stent 1 due to the self-expansion force of the first skeletal portion 11 and the second skeletal portions 12, 13, and in this state, the first skeletal portion 11 and the second skeletal portions 12, 13 are deformable in response to an external force applied from the outer surface side of the bile duct stent 1.

[0018] 2, when the second stent sections 1B, 1C are aligned along the axial direction of the first stent section 1A (i.e., when the second stent sections 1B, 1C are arranged side by side so that their extending directions are the same), the second framework sections 12, 13 are arranged so that they do not overlap in the axial direction (they are offset in the axial direction). This makes it easier to compress the second stent sections 1B, 1C in the radial direction, and therefore makes it easier to store the bile duct stent 1 in a sheath.

[0019] Examples of materials for the metal wires forming the first skeletal portion 11 and the second skeletal portions 12 and 13 include known metals or metal alloys such as stainless steel, Ni-Ti alloy (nitinol), and titanium alloy. An alloy material having X-ray contrast properties may also be used. In this case, the position of the bile duct stent 1 can be confirmed from outside the body. The first skeletal portion 11 and the second skeletal portions 12 and 13 may be formed of materials other than metal materials (e.g., ceramics, resins, etc.).

[0020] The material, wire type (for example, circular wire such as wire, or laser-cut angular wire), wire diameter (cross-sectional area), number of folds in the circumferential direction and fold shape (number of peaks and shape of peaks), and wire spacing in the axial direction (amount of framework per unit length) of the wire forming the first skeletal portion 11 and the second skeletal portion 12, 13 are appropriately selected based on the flexibility of the first stent portion 1A and the second stent portion 1B, 1C required depending on the biological lumen to be placed. Here, flexibility refers to the ease of bending of the first stent portion 1A and the second stent portion 1B, 1C, and is particularly determined by the bending rigidity in the axial direction. In other words, the high flexibility of the first stent portion 1A and the second stent portion 1B, 1C means that the bending rigidity in the axial direction is appropriately low and that the stent portion has the property of following the shape of the biological lumen or sheath without kinking in the biological lumen or sheath.

[0021] Further, a coating portion 14 is disposed on the first stent portion 1A and the second stent portions 1B and 1C so as to cover the peripheral surfaces of the first skeletal portion 11 and the second skeletal portions 12 and 13. The coating portion 14 is a membrane that forms a bile flow path. The coating portion 14 may be disposed on the outer peripheral surface and the inner peripheral surface of the first skeletal portion 11 and the second skeletal portions 12 and 13 so as to sandwich the first skeletal portion 11 and the second skeletal portions 12 and 13, or may be disposed only on the outer peripheral surface or only on the inner peripheral surface of the first skeletal portion 11 and the second skeletal portions 12 and 13.

[0022] Examples of materials that can be used to form the coating portion 14 include silicone resin, fluororesin such as PTFE (polytetrafluoroethylene), and polyester resin such as polyethylene terephthalate.

[0023] In this embodiment, the first stent portion 1A and the second stent portions 1B and 1C are integrated together by integrally forming the coating portion 14. In other words, the first skeletal portion 11 and the second skeletal portions 12 and 13 reinforce the coating portion 14 so as to hold it in a predetermined expanded state.

[0024] Further, on the outer circumferential surfaces of the first skeletal portion 11 and the second skeletal portions 12 and 13, an extension restricting portion 16 is disposed. The extension restriction portion 16 is, for example, arranged along the axial direction of each of the first skeletal portion 11 and the second skeletal portion 12, 13, and is formed of a rectangular elongated member. Specifically, the extension restriction portion 16 is fixed (for example, by adhesion, etc.) to the outer peripheral surface (for example, the inside of the coating portion 14) of the first skeletal portion 11 and the second skeletal portion 12, 13 so as to extend over both ends in the axial direction of the first skeletal portion 11 and the second skeletal portion 12, 13. In addition, two extension restriction portions 16, 16 are arranged at positions rotated 180° in each of the first stent portion 1A and the second stent portion 1B, 1C. Of these, the extension restriction portion 16 arranged on the left side of each of the first stent portion 1A and the second stent portion 1B in FIG. 1 is formed continuously and integrally, and the extension restriction portion 16 arranged on the right side of each of the first stent portion 1A and the second stent portion 1C in FIG. 1 is formed continuously and integrally.

[0025] The elongation control portion 16 is formed, for example, from a biocompatible thread (e.g., polyester thread, etc.) or fabric (woven fabric or knitted fabric) and has a strength capable of controlling the axial elongation of the first skeletal portion 11 and the second skeletal portions 12, 13, at least to the extent that does not impair the radial expandability of the bile duct stent 1.

[0026] The extension restriction portion 16 restricts the axial extension of the biliary stent 1 when it is contracted in the radial direction and housed in the sheath. Therefore, compared with a stent without an extension restriction portion, the axial length of the biliary stent 1 when housed in the sheath is shorter, the contact area between the biliary stent 1 and the sheath is smaller, and the frictional resistance when the biliary stent 1 is released from the sheath is reduced. In addition, the axial shortening rate is reduced when the biliary stent 1 is released from the sheath and the first stent portion 1A and the second stent portions 1B and 1C are in an expanded state, so that the biliary stent 1 can be placed at a desired placement site in the hepatic portal tract HP.

[0027] The extension restricting portion 16 may not be provided, or three or more extension restricting portions 16 may be provided at predetermined intervals in the circumferential direction in each of the first stent portion 1A and the second stent portions 1B and 1C. Also, the extension restricting portion 16 may be provided only in the first stent portion 1A. The extension restricting portion 16 may be provided, for example, on the outside of the coating portion 14. In this case, when the bile duct stent 1 is placed in the hepatic portal portion HP, the bile duct wall comes into contact with the extension restricting portion 16, so that the bile duct wall bites into the extension restricting portion 16. This makes it possible to prevent the bile duct stent 1 from shifting from its placement position. In other words, the extension restricting portion 16 can function as a means for preventing the bile duct stent 1 from shifting.

[0028] Further, a removal assisting portion 15 is connected to the other end (open end) of the first stent portion 1A. The removal assisting part 15 is an assisting tool used when removing the bile duct stent 1 placed in the hepatic portal hilum HP. The removal assisting part 15 has an attachment part to which a hook (snare: retrieval member, not shown) provided at the tip of the retrieval catheter is attached. The attachment part is formed, for example, by bending a wire. The attachment part may have, for example, a hook shape or a loop shape. The wire material forming the removal assisting portion 15 may be, for example, the same as that of the first skeletal portion 11, and may be formed integrally with the first skeletal portion 11. Furthermore, a plurality of removal assisting portions 15 may be provided in the circumferential direction at the open end of the first stent portion 1A. In addition, removal assistance part 15 may be formed of a string-like member made of natural fibers such as plant fibers or animal fibers, or chemical fibers such as synthetic fibers or high-performance fibers. Specific examples of such fibers include nylon fibers, polyester fibers, aramid fibers, and polyethylene fibers.

[0029] Thus, the biliary stent 1 according to the first embodiment is a biliary stent 1 placed in the hepatic portal portion HP (in a living body lumen), and includes a cylindrical first stent portion 1A placed in the common hepatic duct H1 and having a first skeletal portion 11, and cylindrical second stent portions 1B, 1C placed in the right hepatic duct H2 and left hepatic duct H3 branching from the common hepatic duct H1 and having second skeletal portions 12, 13. The first stent portion 1A and the second stent portions 1B, 1C are integrally formed so as to be placed in the common hepatic duct H1, the right hepatic duct H2, and the left hepatic duct H3.

[0030] Specifically, in the biliary stent 1, the first skeletal portion 11 and the second skeletal portions 12 and 13 do not overlap in the radial direction. That is, this is different from a conventional partial stent-in-stent in which multiple stents are connected and partially overlap each other. This allows the bile duct stent 1 to be easily placed in the hepatic portal hilum (HP) (a branching portion of the biological lumen) in a single procedure. This allows for stable surgery regardless of the surgeon's experience or skill. In addition, the mesh of the stent does not get tangled as in conventional methods, and the bile duct stent 1 can be easily removed after placement.

[0031] Moreover, the biliary stent 1 has a coating portion 14 that covers the first skeletal portion 11 and the second skeletal portions 12, 13, and the coating portion 14 integrates the first stent portion 1A and the second stent portions 1B, 1C. This allows the first stent section 1A and the second stent sections 1B and 1C to be integrated regardless of the form of the first skeletal section 11 and the second skeletal sections 12 and 13, thereby improving the degree of freedom in design.

[0032] Moreover, the first skeletal portion 11 and the second skeletal portions 12 and 13 are formed from different wires and are separate from each other. This eliminates the need for a complex weaving design, and allows the first skeletal portion 11 and the second skeletal portions 12, 13 to be easily produced.

[0033] In addition, the bile duct stent 1 has multiple second stent sections 1B, 1C branching off from the same location of the first stent section 1A, and when the second stent sections 1B, 1C are aligned along the axial direction of the first stent section 1A, their respective second skeletal sections 12, 13 are offset in the axial direction. This makes it easier to compress the second stent portions 1B, 1C in the radial direction, making it easier to store the biliary stent 1 in the sheath.

[0034] In the first embodiment, the coating portion 14 is integrally formed, but this is merely an example and is not limiting, and the coating portion 14 may be appropriately and arbitrarily changed. That is, the coating portion 14 may be individually covered with the first skeletal portion 11 and the second skeletal portions 12 and 13. In this case, the first stent portion 1A and the second stent portions 1B and 1C may be integrated by bonding the coating portion 14 arranged on the first stent portion 1A and the coating portion 14 arranged on the second stent portions 1B and 1C, or the first stent portion 1A and the second stent portions 1B and 1C may be integrated by connecting the first skeletal portion 11 and the second skeletal portions 12 and 13.

[0035] In addition, the first skeletal portion 11 and the second skeletal portions 12 and 13 are integrated by the coating portion 14, but this is merely an example and is not limiting, and the first stent portion and the second stent portion, which are separated, may be combined and placed in the branch portion of the hepatic portal portion HP. That is, for example, although not shown, a connection portion with the second stent portion may be provided at the branch portion of the first stent portion extending from the common hepatic duct H1 to the right hepatic duct H2 (or the left hepatic duct H3) to the left hepatic duct H3 (or the right hepatic duct H2), and the second stent portion may be combined with this connection portion and placed in the branch portion of the hepatic portal portion HP. That is, by making the region where the stent portions are combined with each other the right hepatic duct H2 (or the left hepatic duct H3) instead of the common hepatic duct H1, the region where the skeletal portions overlap each other can be reduced. As a method for placing the separated first and second stent portions, for example, a method similar to that of a conventional partial stent-in-stent (not shown) can be applied, and detailed explanation thereof will be omitted here.

[0036] [Second embodiment] FIG. 4 is a diagram showing the appearance of a biliary stent 2 according to the second embodiment. As shown in FIG. 4, the bile duct stent 2 is a so-called bare stent consisting of only a skeleton portion 21. The bile duct stent 2 is divided into a first stent portion 2A and second stent portions 2B and 2C branching off from the first stent portion 2A. The first stent portion 2A is a portion to be placed in the common hepatic duct H1, and the second stent portions 2B and 2C are portions to be placed in the right hepatic duct H2 and the left hepatic duct H3 (see FIGS. 3A and 3B). Although not shown, a removal assistant portion may be connected to the open end portion (lower end portion in FIG. 4) of the first stent portion 2A, as in the first embodiment.

[0037] The biliary stent 2 differs from the first embodiment in that the framework 21 is not covered with a coating portion. Description of the same configuration as the first embodiment will be omitted.

[0038] The skeleton 21 is, for example, a self-expanding stent skeleton in which metal wires are wound in a spiral shape in the axial direction to form a mesh. More specifically, the skeleton 21 has a configuration in which a wire wound in a spiral shape in a clockwise direction and a wire wound in a spiral shape in a counterclockwise direction (including a case in which the same wire is folded back at an end) are crossed and woven together to form a mesh. The skeleton 21 is formed of one or more wires that are continuous across the first stent section 2A and the second stent sections 2B and 2C. The skeleton 21 is configured to be self-expandable in a radial direction substantially perpendicular to each axial direction from a contracted state in which it contracts inward to an expanded state in which it expands outward to define a cylindrical flow path.

[0039] In this way, the skeletal portion 21 (first skeletal portion) of the first stent portion 2A and the skeletal portion 21 (second skeletal portion) of the second stent portions 2B, 2C have a tubular shape that can expand and contract in a radial direction that is approximately perpendicular to their respective axial directions, and due to the self-expansion force of the skeletal portion 21, the outer surface of the bile duct stent 2 presses against the inner surfaces of the common hepatic duct H1, right hepatic duct H2 and left hepatic duct H3, and in this state, the skeletal portion 21 is deformable in response to an external force applied from the outer surface side of the bile duct stent 2.

[0040] The expansion force of the skeleton 21 is controlled by the size of the mesh. Specifically, the mesh of the skeleton 21 is larger in the second stent sections 2B and 2C than in the first stent section 2A, and the expansion force of the skeleton 21 in the second stent sections 2B and 2C is smaller than the expansion force of the skeleton 21 in the first stent section 2A. The expansion forces of the skeleton 21 in the second stent sections 2B and 2C may be set to be different from each other, or may be set to be larger than the expansion force of the skeleton 21 in the first stent section 2A.

[0041] In addition, the framework 21 constituting the first stent section 2A and the second stent sections 2B, 2C is continuously formed from the same wire material, so that the first stent section 2A and the second stent sections 2B, 2C are integrated. This makes it easier to fabricate the bile duct stent 2 compared to a case in which the frameworks 21 of the first stent section 2A and the second stent sections 2B, 2C are fabricated separately and then connected. Note that as long as the framework 21 is continuously formed from the same wire material, the number of wire materials is not particularly limited.

[0042] Therefore, in the bile duct stent 2 of the second embodiment, as in the first embodiment described above, the skeletal portion 21 (first skeletal portion) of the first stent portion 2A and the skeletal portions 21 (second skeletal portion) of the second stent portions 2B, 2C do not overlap radially of the first skeletal portion, but are different from the conventional partial stent-in-stent in which multiple stents are connected and partially overlap each other. This allows the bile duct stent 2 to be easily placed in the hepatic portal hilum (HP) (branching part of the biological lumen) in a single procedure. This allows for stable surgery regardless of the surgeon's experience or skill. In addition, the mesh of the stent does not get tangled as in conventional methods, and the bile duct stent 2 can be easily removed after placement.

[0043] In addition, in the bile duct stent 2, the second stent portions 2B and 2C branch off from one end of the first stent portion 2A, and the skeletal portion 21 (first skeletal portion) of the first stent portion 2A and the skeletal portion 21 (second skeletal portion) of the second stent portions 2B and 2C are formed from the same wire material. This makes it possible to easily prepare the bile duct stent 2 since the step of connecting the framework 21 of the first stent portion 2A to the frameworks 21 of the second stent portions 2B and 2C is not necessary.

[0044] 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 of the invention.

[0045] For example, in the bile duct stent 1 according to the first embodiment, the first stent section 1A and the second stent sections 1B and 1C may be fabricated separately and then connected to each other. Similarly, in the bile duct stent 2 according to the second embodiment, the first stent section 2A and the second stent sections 2B and 2C may be fabricated separately and then connected to each other. Furthermore, for example, in the bile duct stent 1 according to the first embodiment, the first skeletal portion 11 and the second skeletal portions 12, 13 may be formed from the same wire material.

[0046] In addition, in the above embodiment, the first stent portion 1A (2A) is placed in the common hepatic duct H1, and the second stent portion 1B (2B), 1C (2C) are placed in the right hepatic duct H2 and the left hepatic duct H3, but this is merely an example and is not limited to this, and the second stent portion may be combined with another stent portion. That is, for example, as shown in Figures 5A and 5B, a bile duct stent 202 is provided with a short connection portion 202B as a second stent portion at the branching portion of the first stent portion 2A to the right hepatic duct H2, and another stent portion 2D for extension is connected to this connection portion 202B. In this case, the second stent portion (connection portion 202B) and the other stent portion 2D are connected not to the common hepatic duct H1 but to the right hepatic duct H2, and the area where the connection portion 202B and the framework portion 21 of the other stent portion 2D for extension overlap can be reduced.

[0047] For example, the end of the other stent portion 2D may be formed into a flange shape and hooked onto the opening edge of the second stent portion (connection portion 202B). In this case, the axial length of the second stent portion (connection portion 202B) can be essentially 0 (zero). At least one of the biliary stent 202 and the other stent portion 2D may have a coating portion.

[0048] Furthermore, in the above embodiment, the bile duct stent has a Y-shape, but the branch shape is not limited to this. For example, the present invention can be applied to a case where the bile duct stent is branched into a T-shape or a π-shape. Furthermore, the number of second stent portions may be three or more.

[0049] The first skeletal portion of the first stent portion and the second skeletal portion of the second stent portion may be laser cut types formed by subjecting a metallic cylindrical member to laser processing.

[0050] The present invention is not limited to the biliary stents 1 and 2 described in the embodiments, but can be applied to stents placed in branched portions of biological lumens such as digestive tract lumens and blood vessels.

[0051] In addition, in the embodiment, the first stent portions 1A, 2A have a straight cylindrical shape, but this is merely an example and is not intended to be limiting. The first stent portions 1A, 2A may have a curved shape depending on the placement site, or may have a curved shape that follows the shape of the lumen after placement.

[0052] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0053] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2018-133106, filed on July 13, 2018, are incorporated herein by reference in their entirety. [Explanation of symbols]

[0054] 1, 2 Biliary stent (stent) 1A, 2A First stent section 1B, 1C, 2B, 2C Second stent section 11 First skeleton 12, 13 Second skeleton 14 Membrane 15 Removal aid 16 Extension control section 21 Skeleton (first skeletal part, second skeletal part) HP Portion of the liver (lung) H1 common hepatic duct (first lumen) H2 Right hepatic duct (second lumen) H3 left hepatic duct (second lumen)

Claims

1. A stent to be placed in a biological lumen, a first stent portion having a cylindrical shape and a first framework portion, the first stent portion being placed in a first lumen of the body lumen; and two cylindrical second stent portions each having a second framework portion and each being placed in a second lumen branched from the first lumen, The first framework portion and the two second framework portions are connected at a crotch portion where the two second stent portions branch off, Each of the first skeletal portion and the two second skeletal portions is formed by bending a metal wire so that peaks and valleys are alternately formed in a circumferential direction surrounding the respective axial directions, and the peaks and valleys are interwoven so as to interlock with each other in the axial direction. The first skeletal portion and the two second skeletal portions are configured to be self-expandable in a radial direction substantially perpendicular to the axial direction from a contracted state to an expanded state that defines a cylindrical flow path, The first skeletal portion and the two second skeletal portions have different wire diameters and peak heights, so that the radial expansion forces are different between the first skeletal portion and the two second skeletal portions. A stent, characterized in that the first stent portion and the two second stent portions are integrally formed so as to be able to be placed in the first lumen and the second lumen.

2. a coating portion covering the first skeleton portion and the two second skeleton portions; a removal assistant part connected to the bent part of the first framework part on the open end side of the first stent part and having a loop-shaped attachment part, 2. The stent according to claim 1, wherein the first stent portion and the second stent portion are integrated by the coating portion.

3. The two second skeleton portions are connected at the crotch portion, a portion of the removal assist portion connected to the first framework portion is arranged alongside a connection portion between the two second framework portions in the axial direction of the first stent portion; The stent of claim 2.

4. The two second stent sections have a smaller tube diameter than the first stent section. A stent according to claim 2 or 3.

5. The removal assist portion is provided in a plurality of portions in a circumferential direction at the open end portion of the first stent portion. A stent according to any one of claims 2 to 4.

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