Stents

Abstract

Provided is a stent capable of preventing backflow and causing a bodily fluid to flow in one direction from one hollow organ. The stent (1) allows communication between two hollow organs (gallbladder G, duodenum D) and causes a bodily fluid to flow from one hollow organ (gallbladder G) to the other hollow organ (duodenum D), said stent being provided with: a main body section (10) that passes through the inner cavity walls (GW, DW) of the two hollow organs and can be positioned and placed in the axial direction and a direction intersecting the axial direction; and a valve section (20) for preventing the fluid in the main body section from flowing backward.

Description

[Technical field]

[0001] The present invention relates to a stent for forming an internal fistula between two hollow organs. [Background technology]

[0002] Conventionally, there is known a procedure for examining and treating tumors in the esophagus, stomach, duodenum, large intestine, pancreas, biliary tract, gallbladder, etc., surrounding lymph nodes, blood vessels, etc., through the mouth using an ultrasound endoscope (EUS: Endoscopic Ultrasonography). One example of such a procedure is an ultrasound-guided biliary drainage procedure (EUS-BD: EUS-guided biliary drainage) in which an internal fistula is formed by puncturing the gallbladder or bile duct from the duodenum or stomach and placing a stent therein under the guidance of an ultrasound endoscope. Patent Document 1 discloses a medical device that is disposed penetrating adjacent hollow organs and is suitable for forming an internal fistula between these hollow organs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-142790 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the medical device disclosed in Patent Document 1 has a problem in that it cannot allow bodily fluids discharged from an organ to flow in only one direction. For example, the medical device in Patent Document 1 can allow bile to flow directly from the gallbladder to the duodenum, but is not configured to prevent fluid from flowing back from the duodenum to the gallbladder.

[0005] An object of the present invention is to provide a stent that allows unidirectional flow of body fluid from one hollow organ. [Means for solving the problem]

[0006] The stent according to the present invention comprises: A stent that connects two hollow organs and allows a body fluid to flow from one of the two hollow organs to the other hollow organ, The present invention has a main body framework made of a wire that penetrates each of the inner walls of the two hollow organs and can be positioned and placed in the axial direction and the direction intersecting the axial direction. Cylindrical A main body portion, The axial direction of the main body destination a valve portion connected to the end portion and preventing backflow of fluid in the main body portion; The valve portion is a tapered portion that narrows in a flat shape from the tip portion toward the body fluid outlet side, The tapered portion is Valve frame made of wire a membrane disposed along the valve skeleton; Have death, the wire of the valve portion skeleton is folded back in a zigzag shape having a plurality of alternating peaks and valleys, and extends spirally around a central axis in the axial direction, and the plurality of valleys are arranged so as to be convex toward a portion where the valve portion and the main body portion are joined, The plurality of peaks are provided at positions opposing each other in a width direction perpendicular to the axial direction of the tapered portion, and include two peaks whose ends on the outlet side protrude toward the outlet side. . Effect of the Invention

[0007] According to the present invention, bodily fluid from one hollow organ can be caused to flow in one direction. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams showing an example of a state in which a stent is used. [Diagram 2] 2A and 2B are perspective views showing the external appearance of a stent. [Diagram 3] 3A to 3D are diagrams showing an example of a stent placement step. [Figure 4] FIG. 4 is a diagram showing a modified example of the stent. [Diagram 5] FIG. 5 is a diagram showing another example of a state in which a stent is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, a stent 1 applied to endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) will be described as an example of the present invention.

[0010] Fig. 1 is a diagram showing an example of a state in which the stent 1 is used. Fig. 1B is an enlarged view of the drainage site in Fig. 1A, and the flow of bile is indicated by arrows. Fig. 2A and Fig. 2B are perspective views showing the appearance of the stent 1 as viewed from different directions.

[0011] 1A and 1B, the stent 1 is a connecting member used to form an internal fistula that serves as a bile passage between the gallbladder G and the duodenum D, and is placed so as to penetrate the gallbladder wall GW and the duodenum wall DW. The stent 1 connects the gallbladder G and the duodenum D, allowing bile stored in the gallbladder G to flow directly into the duodenum D.

[0012] 2A and 2B, the stent 1 includes a main body portion 10, a valve portion 20 that prevents backflow of fluid in the main body portion 10, and an engagement portion 30 that engages with the lumen walls (including the inner surfaces of through-holes formed in the lumen walls) of two tubular organs to be communicated with. In this embodiment, the engagement portion 30 includes a first engagement portion 31 that engages with the gallbladder wall GW and a second engagement portion 32 that engages with the duodenal wall DW when the stent 1 is placed.

[0013] The main body 10 is formed, for example, in a cylindrical shape having a circular cross-sectional shape perpendicular to the axial direction and a predetermined length in the axial direction. The outer diameter of the main body 10 is larger than the outer diameter of the through-holes GW1, DW1 (see FIG. 3A, etc.) formed in the gallbladder wall GW and the duodenal wall DW, so that the main body 10 is press-fitted into the through-holes GW1, DW1. In addition, the length of the main body 10 is preferably equal to or less than the sum of the thickness of the gallbladder wall GW and the thickness of the duodenal wall DW to be communicated. This allows the gallbladder wall GW and the duodenal wall DW to be reliably held in close contact with each other.

[0014] In the following, one end 10a of the main body 10, which is the far right side in Fig. 2A, is referred to as the "first end 10a," and the other end 10b, which is the near left side in Fig. 2A, is referred to as the "second end 10b." The stent 1 is placed so that the first end 10a is on the upstream side and the second end 10b is on the downstream side in the bile flow direction (see Fig. 1B, etc.).

[0015] The main body 10 has a framework 11 and a coating 12, and is a so-called covered stent. The skeleton 11 has a configuration in which, for example, one or more metal wires are bent so that peaks and valleys are alternately formed and wound in a spiral shape in the axial direction. Alternatively, for example, the skeleton 11 may be formed by arranging a plurality of skeletons, each skeleton being formed in an annular shape by bending a metal wire so that peaks and valleys are alternately formed, at predetermined intervals in the axial direction. The skeleton 11 is configured to be self-expandable in a radial direction substantially perpendicular to the axial direction from a contracted state in which it is contracted inward to an expanded state in which it expands outward to define a cylindrical flow path.

[0016] The material of the wire forming the skeleton 11, the type of wire (for example, a circular wire such as a wire, or an angular wire cut by a laser), the wire diameter (cross-sectional area), the number of folds in the circumferential direction and the shape of the folds (the number of peaks and the shape of the peaks), and the wire spacing in the axial direction (helical pitch (amount of skeleton per unit length)) are appropriately selected based on the flexibility of the main body 10 required depending on the placement site. Here, flexibility refers to the ease of bending of the main body 10, and is particularly determined by the bending rigidity in the axial direction. In other words, the high flexibility of the main body 10 means that the bending rigidity in the axial direction is appropriately low and the main body 10 has the property of following the shape of the placement site or sheath without kinking inside the placement site or sheath.

[0017] Examples of materials for the metal wires forming the skeleton 11 include known metals or metal alloys such as stainless steel, Ni-Ti alloy (nitinol), titanium alloy, etc. Also, an alloy material having X-ray contrast properties may be used. The skeleton 11 may be formed of materials other than metal materials (for example, ceramics, resin, etc.). Moreover, the skeleton 11 may be formed, for example, by laser processing (laser cutting) a single metal pipe (for example, a pipe made of a Ni-Ti alloy). The same applies to the metal wire material forming the skeleton portion 23 provided in the valve portion 20 described later, and the metal wire material forming the first engagement portion 31 and the second engagement portion 32.

[0018] The coating portion 12 is a membrane that forms a bile flow path. The coating portion 12 may be disposed on the outer peripheral surface and the inner peripheral surface of the skeleton portion 11 so as to sandwich the skeleton portion 11, or may be disposed on only one of the outer peripheral surface and the inner peripheral surface of the skeleton portion 11.

[0019] Examples of materials that can be used to form the coating portion 12 include silicone resin, fluororesin such as PTFE (polytetrafluoroethylene), and polyester resin such as polyethylene terephthalate.

[0020] The valve portion 20 allows bile from the gallbladder G to pass in only one direction, and prevents reverse flow (e.g., the flow of digested matter) from the duodenum D. In this embodiment, the valve portion 20 is connected to a second end portion 10b of the main body portion 10 that is downstream in the bile flow direction, and has a bile outlet port 20b. The valve portion 20 is formed of a membrane, similar to the membrane portion 12 of the main body portion 10, and is formed integrally with the membrane portion 12.

[0021] Valve portion 20 is formed, for example, in a tapered shape toward the downstream side in the flow direction of bile (body fluid) in main body portion 10. In this embodiment, valve portion 20 has tapered portion 21 connected to main body portion 10 and flat portion 22 connected to the tip side of tapered portion 21, and is formed in a streamer shape whose outer shape is deformed by fluid pressure.

[0022] The tapered portion 21 is formed such that, from the inlet 20a toward the flat portion 22, the length in the width direction D2 perpendicular to the axial direction hardly changes, while the length in the vertical direction D1, which is approximately perpendicular to the axial direction and the width direction D2, becomes shorter.

[0023] In addition, the tapered portion 21 has a skeleton 23, which is formed by extending a metal wire material folded back in a zigzag shape in a spiral shape, and is arranged along a portion where the skeleton 23 is connected to the main body 10. In addition, the skeleton 23 has two peaks 23a whose end on the tip side (flat portion 22 side) protrudes toward the tip side. The two peaks 23a are provided symmetrically with respect to the axial direction, that is, at positions opposite each other in the width direction D2. By arranging a membrane along the skeleton 23 having the peaks 23a, the tapered portion 21 narrows in a flat shape toward the tip side.

[0024] The flat portion 22 is formed so as to maintain its length in the vertical direction D1 and the width direction D2, and has a flat shape in which the length in the vertical direction D1 (the thickness of the flat portion 22) is smaller than the length in the width direction D2 (the width of the flat portion 22). In addition, an outlet 20b is provided at the end of the flat portion 22 on the bile outflow side (tip side). The outlet 20b is blocked in a straight line when bile is not passing through. On the other hand, when bile is passing through, the outlet 20b is expanded by the internal pressure of the bile, and assumes, for example, an elliptical or rectangular shape. This suppresses the inflow of fluid (e.g., digested matter) from the duodenum D to the main body 10 without impeding the flow of bile. The shape of the outlet 20b when bile is passing through is not particularly limited as long as it is a shape that allows bile to pass through.

[0025] Furthermore, the skeleton 23 may be biased so that the tops of the two peaks 23a are separated from each other in the width direction D2. As a result, when no bile is passing through, the two peaks 23a pull the tip side of the tapered portion 21 (the rear end side of the flat portion 22) away from each other in the width direction D2, so that the outlet 20a can be quickly shifted from the open state to the closed state, and the inflow of fluid from the duodenum D can be effectively prevented.

[0026] The first engagement portion 31 and the second engagement portion 32 are deformable to assume a first shape that follows the axial direction of the main body portion 10 and a second shape that protrudes in a direction intersecting (e.g., approximately perpendicular to) the axial direction of the main body portion 10. The first engagement part 31 and the second engagement part 32 are, for example, stretched or folded in the axial direction to assume a first shape when housed in the sheath 101 (see FIG. 3A, etc.) of the stent placement device 100, and assume a second shape when released from the stent placement device to engage with the lumen wall of a luminal organ (for example, the gallbladder wall GW and the duodenal wall DW). That is, the first engagement part 31 and the second engagement part 32 are configured to be self-deployable. FIGS. 2A and 2B show a case where the first engagement part 31 and the second engagement part 32 assume the second shape.

[0027] The first engaging portion 31 and the second engaging portion 32 are formed of, for example, a shape-memory material (for example, Ni-Ti alloy), and are heat-treated in the second shape to memorize the entire shape. As a result, when the stent 1 is released from the sheath 101 (see FIG. 3A, etc.), the first engaging portion 31 and the second engaging portion 32 are reliably deployed and assume the first shape.

[0028] The first engaging portion 31 and the second engaging portion 32 are formed, for example, by weaving thin metal wires into a mesh shape to present a second doughnut-shaped shape. The first engaging portion 31 and the second engaging portion 32 may be formed integrally with the skeleton portion 11 by the metal wire material forming the skeleton portion 11 of the main body portion 10, or may be formed separately from the main body portion 10. When the first engaging portion 31 and the second engaging portion 32 are formed separately from the main body portion 10, they are connected to the skeleton portion 11 by, for example, crimping.

[0029] The first engagement part 31 that engages with the gallbladder wall GW is preferably connected to the rear end of the first end 10a so that the first end 10a of the main body part 10 does not protrude from the first engagement part 31 when the second shape is assumed. If the first end 10a of the main body part 10 protrudes from the first engagement part 31, bile will flow over the first end 10a on which the membrane part 12 is formed and into the main body part 10, which may hinder the flow of bile. In other words, by connecting the first engagement part 31 to the rear end of the first end 10a, bile can be allowed to flow smoothly into the main body part 10.

[0030] The second shape of the first engagement portion 31 and the second engagement portion 32 can be changed arbitrarily and appropriately, and may be, for example, a flange shape that is crushed in the axial direction rather than a doughnut shape.

[0031] The stent 1 also has a removal assisting portion 40 (lasso) used when removing the placed stent 1. The removal assisting portion 40 is provided, for example, at the second end 10b (downstream end) of the axial ends of the main body portion 10 so as to protrude in the axial direction. The removal assisting portion 40 has an engagement portion 41 to which a hook (snare: retrieval member) provided at the tip of the retrieval catheter is engaged. The engagement portion 41 is formed, for example, by bending a wire, and may have, for example, a hook shape or a loop shape. For example, the same wire as the skeleton portion 11 can be applied to the wire forming the removal assisting portion 40, and the removal assisting portion 40 may be formed integrally with the skeleton portion 11.

[0032] 3A to 3D are diagrams showing an example of a process for placing the stent 1. FIG. In endoscopic ultrasound gallbladder drainage (EUS-GBD), an ultrasound endoscope is introduced orally and delivered to a predetermined site in the duodenum D through the esophagus and stomach. The stent 1 is housed in a sheath 101 of the stent placement device 100 with the first engagement portion 31 and the second engagement portion 32 folded, and introduced into the body via the ultrasound endoscope. The stent placement device 100 is provided with a distal tip 102 on the distal end side of the sheath 101, for example. The distal tip 102 may have an incision portion (not shown) capable of incising the inner wall of a luminal organ by applying high-frequency current, so that the sheath 101 can be inserted while incising the duodenal wall DW and the gallbladder wall GW.

[0033] First, as shown in Fig. 3A, the sheath 101 is passed through the through-holes DW1 and GW1 in the duodenal wall DW and the gallbladder wall GW from the distal tip 102 side of the stent placement device 100. At this time, the ultrasonic endoscope is used to confirm that there are no blood vessels or the like on the puncture line before the puncture is performed.

[0034] Next, with the position of the stent 1 fixed, the sheath 101 is moved proximally relative to the stent 1. As a result, the distal side of the stent 1 begins to deploy. When the sheath 101 is then moved further proximally relative to the stent 1, the first engagement portion 31 of the stent 1 is fully deployed and assumes the second shape (see FIG. 3B).

[0035] In this state, by moving the stent 1 proximally together with the sheath 101, the first engagement portion 31 of the stent 1 is engaged with the gallbladder wall GW. When the stent 1 and the sheath 101 are moved further proximally, the first engagement portion 31 of the stent 1 is engaged with the inner surface of the gallbladder wall GW, so that the gallbladder wall GW is pulled toward the duodenal wall DW, and the outer surface of the gallbladder wall GW and the outer surface of the duodenal wall DW come into close contact with each other (see FIG. 3C). At this time, the portion of the main body 10 of the stent 1 released from the sheath 101 is pressed into the through holes DW1 and GW1 formed in the duodenal wall DW and the gallbladder wall GW, and is positioned in the axial and radial directions. In addition, the first engagement portion 31 of the stent 1 may be released and fully deployed to assume the second shape, without going through the state of Figure 3B, and then the first engagement portion 31 may be engaged with the gallbladder wall GW.

[0036] Next, the sheath 101 is moved further proximally relative to the stent 1. As a result, when the stent 1 is completely released from the sheath 101, the second engagement portion 32 on the proximal side of the stent 1 unfolds to the second shape and is engaged with the inner surface of the duodenal wall DW (see FIG. 3D). When the length of the main body portion 10 of the stent 1 is set to be equal to or less than the thickness of the duodenal wall DW and the gallbladder wall GW, the two are held in a tightly adhered state. At this time, the valve portion 20 is exposed to the duodenum D. Through the above steps, the gallbladder G and the duodenum D are connected by the stent 1, and bile begins to flow from the gallbladder G through the lumen of the stent 1 into the duodenum D.

[0037] In this way, the stent 1 is a stent that connects the gallbladder G and the duodenum D (two hollow organs) and allows bile (body fluid) to flow from the gallbladder G (one hollow organ) to the duodenum D (the other hollow organ), and is equipped with a main body portion 10 that penetrates the gallbladder wall GW and the duodenum wall DW (the inner lumen walls of the two hollow organs) and is positioned in the axial direction and in a direction intersecting the axial direction so that it can be left in place, and a valve portion 20 that prevents backflow of fluid in the main body portion 10. According to the stent 1, the main body 10 can be placed while being positioned in the axial direction and in the direction intersecting the axial direction, and an internal fistula can be formed by properly placing the stent 1. The valve portion 20 can prevent backflow of fluid in the main body 10, and allows bodily fluid (bile) from the gallbladder G, which is one of the hollow organs, to flow in one direction.

[0038] Moreover, the valve portion 20 is formed of a membrane, and this membrane is formed in a tapered shape toward the downstream side in the flow direction of the body fluid in the main body portion 10. As a result, the shape of the valve portion 20 physically blocks the inflow of the fluid into the main body portion 10, and the backflow of the fluid in the main body portion 10 can be reliably prevented.

[0039] Moreover, the valve section 20 is provided at a second end section 10b (one end section in the axial direction) of the main body section 10, and has an outlet section 20b for bile (body fluid) flowing through the main body section 10. This makes it possible to prevent unintended fluids such as digestive matter from flowing into the main body section 10 and causing the main body section 10 to become clogged with digestive matter, etc., and makes it possible to maintain a normal flow state of the main body section 10.

[0040] The stent 1 also includes a cylindrical main body 10, a first engagement portion 31 provided at a first end 10a (at least one end in the axial direction) of the main body 10 and engaging with the gallbladder wall GW, and a second engagement portion 32 provided at a second end 10b and engaging with the duodenal wall DW. This makes it possible to prevent the stent 1 from shifting in the axial direction, and to maintain an appropriate placement state.

[0041] 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.

[0042] For example, as shown in Fig. 4, when a stent 2 without a valve function has already been placed, the stent 1 can be engaged with the placed valveless stent 2. When the placed stent 2 has engagement parts 51, 52 that engage with the gallbladder wall GW and the duodenal wall DW, the first engagement part 31 and the second engagement part 32 of the stent 1 engage with the outer side or the lumen side of the engagement parts 51, 52 of the stent 2, respectively. Also, the main body part 10 of the stent 1 is intimately contacted with the main body part 50 of the stent 2. In this case, since the placed stent 2 prevents leakage of bile, the main body part 10 of the stent 1 only needs to have a framework part 11 that exerts a radial expansion force, and does not need to have a coating part 12.

[0043] For example, in the embodiment, the valve portion 20 has the flat portion 22, but the valve portion 20 does not have to have the flat portion 22. However, the valve function is improved when the valve portion 20 has the flat portion 22 as in the embodiment. Furthermore, the valve portion 20 does not have to have the skeletal portion 23. For example, by forming a membrane along a base material having the same shape as the valve portion 20, the shape of the valve portion 20 can be maintained even without the skeletal portion 23.

[0044] Furthermore, the valve unit 20 may be formed of a separate member from the main body unit 10 and connected to one end (for example, the first end 10a) of the main body unit 10. The valve unit 20 may be provided inside the main body unit 10, or may be provided both inside and at one end of the main body unit 10. When the valve unit 20 is provided inside the main body unit 10, for example, a structure in which a flow state and a blocked state are switched by opening and closing a valve body, such as an artificial heart valve, can be applied. Furthermore, the valve unit 20 may be provided at a plurality of locations inside the main body unit 10.

[0045] Furthermore, the main body 10 may be configured as a bare stent consisting of only the skeletal portion 11, without the coating portion 12. In this case, the meshes of the skeletal portion 11 may be made extremely small, or the skeletal portion 11 may be stacked in multiple layers, thereby preventing leakage of bodily fluids (e.g., bile) flowing down the main body 10 from the main body 10.

[0046] Furthermore, the stent 1 may be configured to include only one of the first engagement portion 31 and the second engagement portion 32 (for example, the first engagement portion 31) (see stent 1A in FIG. 5), or may be configured to include neither (not shown). In a stent that does not include both the first engagement portion 31 and the second engagement portion 32, when the main body portion 10 is press-fitted into the through-holes DW1, GW1 of the duodenal wall GW and the gallbladder wall DW, for example, the framework portion 11 is embedded in the through-holes DW1, GW1 to function as the engagement portion 30 and is positioned in the axial and radial directions.

[0047] The stent of the present invention can be used not only for endoscopic ultrasound-guided gallbladder drainage (EUS-GBD), but also for all drainage procedures performed under an ultrasound endoscope, such as EUS-guided hepaticogastrostomy (EUS-HGS), which connects the stomach and bile duct, and EUS-guided choledochoduodenostomy (EUS-CDS), which connects the duodenum and bile duct.

[0048] 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.

[0049] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2019-161292, filed on September 4, 2019, are incorporated herein by reference in their entirety. [Explanation of symbols]

[0050] 1. 1A stent 10 Main body 10a First end 10b Second end 12 Membrane 20 Valve section 20b Outlet 30 Engagement part 31 First engagement portion 32 Second engagement portion

Claims

1. A stent that connects two hollow organs and allows a body fluid to flow from one of the two hollow organs to the other hollow organ, a cylindrical main body portion having a main body framework portion made of a wire material, the main body portion penetrating each of the inner walls of the two hollow organs and capable of being positioned and placed in an axial direction and a direction intersecting the axial direction; a valve portion connected to a tip end portion of the main body portion in the axial direction and configured to prevent a backflow of a fluid in the main body portion, the valve portion has a tapered portion that narrows from the tip portion of the main body portion toward the body fluid outlet side, the tapered portion has a valve portion skeleton made of a wire material and a membrane body disposed along the valve portion skeleton, the wire of the valve portion skeleton is folded back in a zigzag shape having a plurality of alternating peaks and valleys, and extends spirally around a central axis in the axial direction, and the plurality of valleys are arranged so as to be convex toward a portion where the valve portion and the main body portion are joined, The plurality of peaks are provided at positions opposing each other in a width direction perpendicular to the axial direction of the tapered portion, and include two peaks whose ends on the outlet side protrude toward the outlet side. Stent.

2. 2. The stent according to claim 1, wherein the valve portion has a flat portion having one end connected to the tapered portion and the outlet port at the other end, and the length in the up-down direction perpendicular to the axial direction and the width direction and the length in the width direction are maintained.

3. The cylindrical main body portion; The stent according to claim 1 or 2, further comprising an engagement portion provided at least at one end of the main body in the axial direction and adapted to engage with an inner wall of at least one of the two hollow organs.

Images