Biliary 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 is directed to a device for placement in a biological lumen. bile duct Regarding stents. [Background technology]

[0002] Stents have been known that are placed in narrowed or obstructed areas in biological lumens, such as blood vessels, the esophagus, the bile duct, the trachea, and the ureter, to expand the diameter of the lesion and maintain the patency of the biological lumen. In stent graft placement, a branched stent may be placed depending on the condition of the lesion. For example, for a lesion near the porta hepatis, the common hepatic duct branches into the right hepatic duct and the left hepatic duct (bile ducts within the liver), so stents must be placed in each of the common hepatic duct, the right hepatic duct, and the left hepatic duct.

[0003] In such cases, conventionally, multiple stents are prepared, such as a stent for a main lumen (e.g., the common hepatic duct) and a stent for a branch lumen (e.g., the right hepatic duct and the left hepatic duct), and one stent is inserted into the opening of one stent (e.g., the mesh of the skeletal part), 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 across from the common hepatic duct to one hepatic duct (e.g., the right hepatic duct) is inserted into the other hepatic duct (e.g., the left hepatic duct) and connected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-138851 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 result in deformation or damage of the stent or blockage of the hepatic portal vein. Furthermore, the mesh of the stent may become entangled, making it difficult to remove after placement. Therefore, the practitioner performing the stent placement procedure must have ample experience and high skill.

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

[0007] The present invention bile duct The stent is Placed inside a living lumen bile duct 1. A stent comprising: 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 biological lumen; two cylindrical second stent portions each having a second framework portion and placed in a second lumen branching from the first lumen; a coating portion that covers the first skeleton portion and the two second skeleton portions; a string-like removal assisting part connected to the first framework part on the open end side of the first stent part opposite to the two second stent parts; Equipped with The first framework portion and the two second framework portions are connected at a bifurcation portion where the two second stent portions branch off, The two second skeletal portions are connected at the crotch portion, Each of the first skeletal portion and the two second skeletal portions is formed by bending metal wires 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 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 heights of peaks, and therefore have different radial expansion forces, the first stent portion and the two second stent portions are integrated by the coating portion, 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. The first skeletal portion and the two second skeletal portions reinforce the membrane portion so as to hold the membrane portion in a predetermined expanded state, The removal assisting portion is connected to the first skeletal portion so as to be aligned in the axial direction of the connection portion between the two second skeletal portions and the first stent portion, and extends to the opposite side to the two second stent portions. It is characterized by: [Effects of the Invention]

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

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

[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 will be described that 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 obstructed or narrowed portion of the hepatic hilum HP) 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 the state in which second stent sections 1B and 1C are joined together along the axial direction of a first stent section 1A of the biliary stent 1. Fig. 3 is a diagram showing the placement of the biliary stent 1. Fig. 3B shows an enlarged view of the hepatic hilum 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 off from the first stent portion 1A. As shown in Figures 3A and 3B, the first stent portion 1A is the portion to be placed in the common hepatic duct H1, and the second stent portions 1B and 1C are the portions to be placed in the right hepatic duct H2 and left hepatic duct H3.

[0013] The first stent section 1A and the second stent sections 1B, 1C have a tubular shape that defines a bile flow path. In this embodiment, the second stent sections 1B, 1C have a smaller tube diameter than the first stent section 1A and are connected to one end of the first stent section 1A so as to branch into two. In other words, the bile duct stent 1 has an overall Y-shape. The angle of the bifurcation section 1a where the second stent sections 1B, 1C branch is set according to the shape of the hepatic portal vein HP where the bile duct stent 1 is to be 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 spirally in the axial direction while bending them so that peaks and valleys are alternately formed. The second skeletal portions 12, 13 are configured, for example, such that a plurality of skeletons formed in an annular shape by bending 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 at the crotch portion 1a or may be separated. The first skeletal portion 11 may be configured with a plurality of annular skeletons formed by bending a metal wire so that peaks and valleys are alternately formed, and the skeletons are arranged at predetermined intervals in the axial direction. The second skeletal portions 12 and 13 may be configured with one or more metal wires wound helically in the axial direction while being bent so that peaks and valleys are alternately formed. The first skeletal portion 11 and the second skeletal portions 12 and 13 may be configured, for example, by weaving the bent portions of the wire so that they interlock with each other, thereby improving the flexibility of each skeletal portion and restricting deformation (elongation) in the axial direction. The first skeletal portion 11 and the second skeletal portions 12 and 13 may be configured, for example, by weaving a wire wound helically clockwise and a wire wound helically counterclockwise (including a case where the same wire is folded back at its end) so that they cross each other to form a mesh, thereby improving the straightness of each skeletal portion. Therefore, for example, the first skeletal portion 11 can be configured by interlocking and weaving the bent portions of the wire material, and the second skeletal portions 12 and 13 can be configured by intersecting and weaving the wire material, thereby creating a bile duct stent 1 having a first skeletal portion 11 that has improved flexibility and restricts axial deformation, and second skeletal portions 12 and 13 that have improved straightness.

[0016] The expansion forces 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 portions 12, 13. In this embodiment, the expansion forces of the first skeletal portion 11 and the second skeletal portions 12, 13 are 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 forces of the second skeletal portions 12, 13 are 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 greater 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 biliary 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 biliary 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 can deform in response to an external force applied from the outer surface of the biliary stent 1.

[0018] 2, when the second stent sections 1B and 1C are aligned along the axial direction of the first stent section 1A (i.e., when the second stent sections 1B and 1C are arranged side by side so that they extend in the same direction), the second framework sections 12 and 13 are not positioned to overlap in the axial direction (they are offset in the axial direction). This makes it easier to compress the second stent sections 1B and 1C in the radial direction, making it easier to store the biliary 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, 13 include known metals or metal alloys such as stainless steel, Ni-Ti alloy (nitinol), and titanium alloy. Also, an alloy material having X-ray contrast properties may be used. In this case, the position of the biliary stent 1 can be confirmed from outside the body. The first skeletal portion 11 and the second skeletal portions 12, 13 may be formed from materials other than metal materials (for example, ceramics, resins, etc.).

[0020] The material, wire type (e.g., circular wire or laser-cut angular wire), wire diameter (cross-sectional area), number of circumferential folds and fold shape (number and shape of peaks), and axial wire spacing (amount of skeletal structure per unit length) of the wires forming the first skeletal structure 11 and the second skeletal structure 12, 13 are appropriately selected based on the flexibility of the first stent structure 1A and the second stent structure 1B, 1C required for the biological lumen in which they are to be placed. Here, flexibility refers to the ease with which the first stent structure 1A and the second stent structure 1B, 1C bend, and is particularly determined by their axial bending rigidity. That is, the first stent structure 1A and the second stent structure 1B, 1C have high flexibility when their axial bending rigidity is appropriately low, allowing them to conform to the shape of the biological lumen or sheath without kinking within the biological lumen or sheath.

[0021] Furthermore, 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 circumferential 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 arranged on the outer and inner peripheral surfaces 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 arranged only on the outer peripheral surfaces or only on the inner peripheral surfaces 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 section 1A and the second stent sections 1B and 1C are integrated together by integrally forming the coating section 14. In other words, the first skeletal section 11 and the second skeletal sections 12 and 13 reinforce the coating section 14 so as to maintain it in a predetermined expanded state.

[0024] Further, on the outer peripheral surfaces of the first skeletal portion 11 and the second skeletal portions 12 and 13, extension restricting portions 16 are arranged. The extension restricting portions 16 are, for example, arranged along the axial direction of each of the first skeletal portion 11 and the second skeletal portions 12, 13 and formed of a rectangular elongated member. Specifically, the extension restricting portions 16 are fixed (e.g., by adhesive) to the outer peripheral surfaces (e.g., the inner surfaces of the coating portions 14) of the first skeletal portion 11 and the second skeletal portions 12, 13 so as to extend across both axial ends of the first skeletal portion 11 and the second skeletal portions 12, 13. Furthermore, two extension restricting portions 16, 16 are arranged in positions rotated 180° in each of the first stent portion 1A and the second stent portion 1B, 1C. Of these, the extension restricting portions 16 arranged on the left side of each of the first stent portion 1A and the second stent portion 1B in FIG. 1 are formed as a continuous, integral unit, and the extension restricting portions 16 arranged on the right side of each of the first stent portion 1A and the second stent portion 1C in FIG. 1 are formed as a continuous, integral unit.

[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 strength that is 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 it does not impair the radial expandability of the biliary stent 1.

[0026] The extension-restricting portion 16 restricts axial extension of the biliary stent 1 when it is contracted radially and housed in the sheath. Therefore, compared to a stent without an extension-restricting 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 frictional resistance when the biliary stent 1 is released from the sheath is reduced. Furthermore, the axial shortening rate is reduced when the first stent portion 1A and the second stent portions 1B and 1C are expanded after the biliary stent 1 is released from the sheath, so the biliary stent 1 can be placed at the desired placement site in the hepatic hilum HP.

[0027] The extension restricting portion 16 may not be provided, or three or more 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. Alternatively, the extension restricting portion 16 may be provided only in the first stent portion 1A. The extension restricting portion 16 may also be provided, for example, on the outside of the membrane portion 14. In this case, when the biliary stent 1 is placed in the hepatic portal hilum 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 prevents the biliary stent 1 from shifting from its placement position. In other words, the extension restricting portion 16 can function as a means for preventing the biliary stent 1 from shifting.

[0028] Furthermore, a removal assisting part 15 is connected to the other end (open end) of the first stent part 1A. The removal assisting part 15 is an auxiliary 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, the removal assisting 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, and specific examples include nylon fibers, polyester fibers, aramid fibers, and polyethylene fibers.

[0029] As described above, the biliary stent 1 according to the first embodiment is a biliary stent 1 placed in the hepatic portal hilum HP (inside a biological 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 and 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 and 13. The first stent portion 1A and the second stent portions 1B and 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 biliary stent 1 to be easily placed in the hepatic portal vein (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. Furthermore, the mesh of the stent does not become tangled as in conventional methods, and the biliary stent 1 can be easily removed after placement.

[0031] The biliary stent 1 also 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] 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 braiding design, and the first skeletal portion 11 and the second skeletal portions 12, 13 can 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, the 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, a configuration in which the coating portion 14 is integrally formed has been exemplified. However, this is merely an example and is not limiting, and the configuration of the coating portion 14 can be changed as appropriate. That is, a configuration in which the first skeletal portion 11 and the second skeletal portions 12, 13 are individually covered may be used. In this case, the first stent portion 1A and the second stent portions 1B, 1C may be integrated by bonding the coating portion 14 arranged on the first stent portion 1A to the coating portion 14 arranged on the second stent portions 1B, 1C, or the first stent portion 1A and the second stent portions 1B, 1C may be integrated by connecting the first skeletal portion 11 to the second skeletal portions 12, 13.

[0035] Furthermore, the first skeletal portion 11 and the second skeletal portions 12 and 13 are configured to be integrated by the coating portion 14. However, this is merely an example and is not limiting. Separate first and second stent portions may be combined and placed in a branched portion of the hepatic hilum HP. That is, for example, although not shown, a connecting portion with the second stent portion may be provided at the branched portion of the first stent portion extending from the common hepatic duct H1 to the right hepatic duct H2 (or left hepatic duct H3) to the left hepatic duct H3 (or right hepatic duct H2), and the second stent portion may be combined with this connecting portion and placed in the branched portion of the hepatic hilum HP. In other words, by combining the stent portions in the right hepatic duct H2 (or left hepatic duct H3) rather than the common hepatic duct H1, the overlapping area of ​​the skeletal portions can be reduced. As a method for placing the separated first and second stent sections, for example, a method similar to that of a conventional partial stent-in-stent can be applied, although this is not shown in the figures, and detailed explanation 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 biliary stent 2 is a so-called bare stent consisting only of a framework portion 21. The biliary 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 the portion to be placed in the common hepatic duct H1, and the second stent portions 2B and 2C are the 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 assisting portion may be connected to the open end (lower end 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 framework 21 is, for example, a self-expanding stent framework in which metal wires are wound in a spiral shape in the axial direction to form a mesh. More specifically, the framework 21 has a configuration in which wires wound in a spiral shape in the clockwise direction and wires wound in a spiral shape in the counterclockwise direction (including cases in which the same wires are folded back at their ends) are interwoven and crossed with each other to form a mesh. The framework 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 the self-expansion force of the skeletal portion 21 causes the outer surface of the bile duct stent 2 to press 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 can deform in response to an external force applied from the outer surface of the bile duct stent 2.

[0040] The expansive force of the skeleton 21 is controlled by the size of the mesh. Specifically, the mesh of the skeleton 21 in the second stent sections 2B and 2C is larger than that in the first stent section 2A, and the expansive force of the skeleton 21 in the second stent sections 2B and 2C is smaller than that of the skeleton 21 in the first stent section 2A. The expansive forces of the skeletons 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 expansive force of the skeleton 21 of the first stent section 2A.

[0041] Furthermore, the framework 21 that constitutes the first stent section 2A and the second stent sections 2B, 2C is continuously formed from the same wire material, thereby integrating the first stent section 2A with the second stent sections 2B, 2C. This makes it easier to fabricate the bile duct stent 2 compared to when the frameworks 21 of the first stent section 2A and the second stent sections 2B, 2C are fabricated separately and then connected. Note that the number of wire materials is not particularly limited as long as the framework 21 is continuously formed from the same wire material.

[0042] Therefore, in the bile duct stent 2 according to the second embodiment, as in the first embodiment, 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 and 2C do not overlap radially of the first skeletal portion, and are different from conventional partial stent-in-stents in which multiple stents are connected and partially overlap each other. This allows the biliary stent 2 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. Furthermore, the mesh of the stent does not become tangled as in conventional methods, and the biliary 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 eliminates the need for a step of connecting the framework 21 of the first stent section 2A to the frameworks 21 of the second stent sections 2B and 2C, and therefore the bile duct stent 2 can be easily produced.

[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 thereof.

[0045] For example, in the biliary 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 together. Similarly, in the biliary 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 together. Furthermore, for example, in the biliary 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 portions 1B (2B), 1C (2C) are placed in the right hepatic duct H2 and the left hepatic duct H3, but this is just one example and is not limited to this, and the second stent portion may be combined with another stent portion. 5A and 5B, a biliary stent 202 has a short connecting 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 connecting portion 202B. In this case, the second stent portion (connecting portion 202B) and the other stent portion 2D are connected at the right hepatic duct H2 rather than the common hepatic duct H1, which can reduce the area where the connecting portion 202B and the framework portions 21 of the other stent portion 2D for extension overlap.

[0047] For example, the end of the other stent section 2D may be formed into a flange shape and hooked onto the opening edge of the second stent section (connection section 202B), in which case the axial length of the second stent section (connection section 202B) can be made 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 biliary duct stent has been shown to have a Y-shape, but the branching shape is not limited to this. For example, the present invention can be applied to a bile duct stent that branches 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 laser processing a metallic cylindrical member.

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

[0051] Furthermore, in the embodiment, the first stent sections 1A, 2A are shown to have a straight cylindrical shape, but this is merely an example and is not limiting; they 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 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.

[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 Coating 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 biliary 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 biological lumen; two second stent portions each having a cylindrical shape and a second framework portion, the second stent portions being placed in a second lumen branching from the first lumen; a coating portion covering the first skeleton portion and the two second skeleton portions; a string-like removal assisting part connected to the first framework part at an open end side of the first stent part opposite to the two second stent parts, the first framework portion and the two second framework portions are connected at a bifurcation portion where the two second stent portions branch off, The two second skeleton portions are connected at the crotch portion, Each of the first skeletal portion and the two second skeletal portions is formed by bending metal wires 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 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 crest heights, and therefore have different radial expansion forces, the first stent portion and the two second stent portions are integrated by the coating portion, and are formed so that the first stent portion and the two second stent portions can be placed as a unit in the first lumen and the second lumen, and the first skeleton portion and the two second skeleton portions reinforce the coating portion so as to hold it in a predetermined expanded state, a bile duct stent having a distal end that is proximal to the distal end of the first stent section and a distal end that is distal to the distal end of the second stent section;

2. The removal assisting portion is connected to the bending portion of the first skeletal portion on the open end side of the first stent portion and has a loop-shaped attachment portion. The biliary stent of claim 1.

3. The two second stent sections have a smaller tube diameter than the first stent section. The biliary stent of claim 2.

4. The height of the peaks of the two second skeletal parts is higher than that of the first skeletal part. The biliary stent of claim 1.

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