JP7534734B2 - Tube Stent - Google Patents

Description

The present invention relates to a tube stent that is placed in the bile duct, pancreatic duct, etc. to maintain an open state or prevent blockage of the bile duct, pancreatic duct, etc.

Drainage (stent placement) has been commonly performed in which a tube stent is placed endoscopically to drain fluid from a body cavity. Known examples of tube stents used in stent placement include those disclosed in Patent Documents 1 and 2 below.

Patent Document 1 discloses an endoscopic drainage tube that is characterized in that a plurality of elongated holes are formed in the sidewall of a flexible tube with openings near both ends, the elongated holes being elongated in the axial direction of the flexible tube at different positions in the circumferential direction so as to overlap in the axial direction. This endoscopic drainage tube realizes both the drainage of pancreatic juice from the pancreatic duct and the drainage of bile from the bile duct, and by providing a plurality of side holes at the end located at the back of the bile duct, a flow path for bile in the bile duct is formed by the openings at the end of the tube and the side holes.

Patent Document 2 discloses a medical retention tube that has multiple openings arranged side by side near both ends and is inserted into the body via an endoscope to be retained at a desired position, characterized in that one or more openings are drilled in a direction perpendicular to the plane of the circle that forms the curling in the circular curling sections provided at both ends of the tube. In this medical retention tube, a flow path for liquid within the body is formed by one or more openings drilled in a direction perpendicular to the plane of the circle that forms the curling.

JP 2002-78806 A Publication No. 4-51805

In the endoscopic drainage tube disclosed in Patent Document 1, multiple side holes are provided at arbitrary positions on the end portion located at the back side of the bile duct to form a bile flow path. However, a flow path passing through multiple side holes located at arbitrary positions cannot ensure a sufficient flow rate, and there are cases where an appropriate open state cannot be achieved.

In addition, in the medical indwelling tube disclosed in Patent Document 2, one or more openings are formed in a direction perpendicular to the plane of the circle that forms the curling. However, this opening is positioned taking into consideration the strength of the curling part and the change in opening area due to its curved shape, and there are cases where a sufficient flow rate cannot be ensured and an appropriate open state cannot be achieved.

In view of the above problems, the present invention aims to provide a tube stent that has a simple structure, can achieve an appropriate patency, and can effectively and reliably drain bile or pancreatic juice into the duodenum.

To achieve the above object, the tube stent of the present invention is a tube stent made of a flexible tube member, and is composed of a straight body portion having a substantially straight shape, a first curved portion having a curved shape connected to one end of the straight body portion, and a second curved portion having a curved shape connected to the other end of the straight body portion, and a first through hole is provided at a position where the approximate central axis of the lumen formed in the straight body portion intersects with the peripheral wall of the first curved portion, and a second through hole is provided at a position where the approximate central axis of the lumen formed in the straight body portion intersects with the peripheral wall of the second curved portion.

This configuration allows the first through hole, the lumen in the straight body portion, and the second through hole to be arranged in a substantially straight line, forming a substantially straight flow path and enabling smooth liquid flow from the first through hole to the second through hole.

Furthermore, in the tube stent according to the present invention, the first through-hole may be provided on the outer edge side of the curved shape of the first curved portion, and the second through-hole may be provided on the outer edge side of the curved shape of the second curved portion.

With this configuration, a first through hole can be provided at a position where the peripheral wall of the first curved section intersects with the axial direction of the straight body portion, and a second through hole can be provided at a position where the peripheral wall of the second curved section intersects with the axial direction of the straight body portion.

Furthermore, in the tube stent according to the present invention, the first through hole and the second through hole may have an opening area larger than the cross-sectional area of the lumen formed in the straight body portion.

This configuration makes it possible to increase the maximum flow rate of liquid passing through the first and second through holes relative to the maximum flow rate of liquid in the lumen within the straight body portion, thereby preventing the first and second through holes from becoming bottlenecks.

Furthermore, in the tube stent according to the present invention, the first through hole may be elongated along the extending direction of the tube member constituting the first curved portion, and the second through hole may be elongated along the extending direction of the tube member constituting the second curved portion.

This configuration allows the first through hole and the second through hole to be formed with the desired opening area while maintaining sufficient strength of the tube stent. In addition, the first through hole and the second through hole can be formed by cutting the first curved portion and the second curved portion with a blade or the like along the extension direction of the tube member, making it easy to manufacture the tube stent.

Furthermore, the tube stent according to the present invention may use a cut hole cut into the peripheral wall of the second curved portion toward the straight body portion as the second through hole, and may be provided with a flap having a base end connected to the tube member on the straight body portion side of the cut hole, and a tip end protruding from the base end to the opposite side to the straight body portion.

With this configuration, a flap can be formed near the second through hole by the incision that forms the second through hole. This flap acts as a movement restriction member that restricts the movement (migration) of the tube stent, and also acts as a foreign object intrusion prevention member that prevents foreign objects from entering the second through hole.

Furthermore, the tube stent according to the present invention may have a shape in which the flap protrudes from the base end toward the tip end and away from the cut hole.

This configuration allows the flap to interfere (contact) with the duodenal papilla or the inner wall of the bile duct as a movement restriction member, and to prevent foreign matter from entering the second through-hole as a foreign matter entry prevention member.

Furthermore, in the tube stent according to the present invention, the radius of curvature of the curved shape of the second curved portion may be smaller than the radius of curvature of the curved shape of the first curved portion.

With this configuration, when the tube stent is placed in the bile duct, the second curved portion is reliably curved in the duodenum, and the end of the tube stent does not come into contact with the inner wall of the duodenum.

Furthermore, the tube stent according to the present invention may have an endoscopic marker provided near the second through hole of the second curved portion.

This configuration makes it easy to check the position of the second curved portion and the second through hole of the tube stent under endoscopic images, making it possible to accurately and easily position the tube stent when placing it in the bile duct.

Furthermore, the tube stent of the present invention may be used as a bile duct tube stent or a pancreatic duct tube stent.

The present invention provides a tube stent that has a simple structure and can achieve an appropriate patency state, allowing bile or pancreatic juice to be efficiently and reliably discharged into the duodenum.

FIG. 1 is a perspective view showing an example of a tube stent in an embodiment of the present invention. FIG. 2 is a longitudinal cross-sectional view of the tube stent shown in FIG. 1. FIG. 3 is a plan view showing an example of a tube stent delivery device for placing a tube stent in a bile duct in an embodiment of the present invention. FIG. 4 is a plan view showing the inner catheter of the tube stent delivery device shown in FIG. 3. FIG. 4 is a plan view showing the outer catheter of the tube stent delivery device shown in FIG. 3. FIG. 2 is a schematic diagram showing a state in which a tube stent according to an embodiment of the present invention is placed in a bile duct. 13 is a schematic diagram showing another state in which a tube stent according to an embodiment of the present invention is placed in a bile duct. FIG. 1A to 1D are diagrams showing the tube shapes used in an embodiment of the present invention, where (a) is a diagram showing the shape of tube A, (b) is a diagram showing the shape of tube B, (c) is a diagram showing the shape of tube C, and (d) is a diagram showing the shape of tube D. 1A is a diagram showing the configuration of an embodiment of the present invention, FIG. 1B is a diagram showing the configuration of a comparative example 1, FIG. 1C is a diagram showing the configuration of an embodiment 2, and FIG. 1D is a diagram showing the configuration of a comparative example 2.

The following describes a tube stent according to an embodiment of the present invention with reference to the drawings.

The tube stent according to the present invention is a bile duct tube stent or pancreatic duct tube stent that is placed in a narrowed portion of the bile duct or pancreatic duct to improve the flow of bile or pancreatic juice. In the following, this specification describes the application of the present invention to a bile duct tube stent that is placed in the bile duct to improve the flow of bile.

Figure 1 is a perspective view showing an example of a tube stent in an embodiment of the present invention, and Figure 2 is a longitudinal cross-sectional view of the tube stent shown in Figure 1.

The tube stent 1 in this embodiment is made of a flexible tube member made of a resin such as polyethylene. The tube stent 1 is manufactured by molding and processing the tube member into a predetermined shape, and has a configuration in which a distal end curved portion 12 and a proximal end curved portion 13 are connected via a straight body portion 11. More specifically, the tube stent 1 in this embodiment is generally configured to include a straight body portion 11 having a substantially linear shape, a distal end curved portion (first curved portion) 12 having a curved shape connected to one end of the straight body portion 11, and a proximal end curved portion (second curved portion) 13 having a curved shape connected to the other end of the straight body portion 11.

In this specification, the extension direction of the straight body portion 11 may be described as the longitudinal direction of the tube stent 1. In addition, in this specification, the end portion that is located deep inside the bile duct when the tube stent 1 is placed in the bile duct is defined as the distal end side of the tube stent 1, and the end portion that is located on the duodenal side when the tube stent 1 is placed in the bile duct is defined as the proximal end side of the tube stent 1.

The straight body portion 11 is the central portion of the tube stent 1 that extends in the longitudinal direction of the flexible tube member that constitutes the tube stent 1. The straight body portion 11 has a substantially linear shape.

The term "approximately straight" refers to a shape that is approximately straight in a natural state where no external load is applied, and more specifically, refers to, for example, the approximate central axis of the lumen in the tube member (a virtual axis passing through the approximate center of the lumen cross section) being approximately straight. Note that the straight body portion 11 may be a gently curved shape that matches the shape of the bile duct, and the term "approximately straight" includes such a gently curved shape that matches the shape of the bile duct.

The distal curved portion 12 is the end of the flexible tube member constituting the tube stent 1 that is disposed in the bile duct when the tube stent 1 is placed in the bile duct. The distal curved portion 12 has a curved shape, and may be, for example, a shape called a pigtail type or an alpha loop type.

The term "curved shape" refers to a shape that is curved in its natural state when no external load is applied, and more specifically, refers to a shape in which, for example, the approximate central axis of the lumen inside the tube member (a virtual axis passing through the approximate center of the lumen cross section) is curved.

The distal curved section 12 may be curved at approximately the same curvature (approximately a perfect circle), or may be curved only partially or at different curvatures. In addition, although Figs. 1 and 2 show a case in which the tube member constituting the distal curved section 12 is curved so as to be included in a specific plane, the tube member may be curved while moving perpendicularly to the curved surface (spiral shape).

The proximal curved portion 13 is the end of the tube stent 1 that is located on the duodenal side when the tube stent 1 is placed in the bile duct, in the flexible tube member that constitutes the tube stent 1. The proximal curved portion 13 has a curved shape, and may be, for example, a shape called a pigtail type or an alpha loop type.

Like the distal curved section 12, the proximal curved section 13 may be curved at approximately the same curvature (approximately a perfect circle), or may be curved only partially or at different curvatures. In addition, while Figures 1 and 2 show a case in which the tube member constituting the proximal curved section 13 is curved so as to be included in a specific plane, the tube member may be curved while moving perpendicular to the curved surface (spiral shape).

The distal end curved portion 12 and the proximal end curved portion 13 may each have an independent curved shape. That is, the distal end curved portion 12 and the proximal end curved portion 13 may have the same curved shape, or may have different curved shapes. As a preferred example, FIG. 1 and FIG. 2 show a case in which the curved shape of the distal end curved portion 12 is set to be gentler than the curved shape of the proximal end curved portion 13. For example, when the curves along the distal end curved portion 12 and the proximal end curved portion 13 are approximated by a circle, the curvature of the approximated circle obtained from the distal end curved portion 12 is set to be smaller than the curvature of the approximated circle obtained from the proximal end curved portion 13. In other words, the radius of curvature of the approximated circle obtained from the proximal end curved portion 13 is set to be smaller than the radius of curvature of the approximated circle obtained from the distal end curved portion 12. That is, the proximal curved portion 13 is relatively smaller than the distal curved portion 12, and the distal curved portion 12 is set to be larger than the proximal curved portion 13.

By making the proximal curved portion 13 smaller relative to the distal curved portion 12, when the tube stent 1 is placed in the bile duct, the proximal curved portion 13 can reliably assume a curved shape in the duodenum. In the past, there have been reported cases in which the proximal end face of the tube stent 1 abutted against the inner wall of the duodenum (the inner wall facing the duodenal papilla), causing ulcers or perforations in the inner wall. However, the tube stent 1 according to the present invention is configured so that the proximal curved portion 13 can reliably assume a curved shape in the duodenum, and the proximal end face of the tube stent 1 does not abut against the inner wall of the duodenum.

The tube stent 1 has a size that allows it to be placed in the bile duct of a patient, and may be prepared in various sizes depending on the patient's physique, etc. As an example, the longitudinal dimension of the tube member constituting the tube stent 1 is about 30 mm to 300 mm. Furthermore, when both ends of the tube member are processed into a distal end curved portion 12 and a proximal end curved portion 13, which are curved, the longitudinal dimension of the tube stent 1 is about 15 mm to 200 mm. In particular, the approximate dimension of the proximal end curved portion 13, which is placed in the duodenum when the tube stent 1 is placed in the bile duct, is preferably smaller than the inner diameter of the duodenum, for example, about 5 mm to 20 mm. Furthermore, the approximate dimension of the distal end curved portion 12 is preferably, for example, 10 mm to 50 mm. In addition, the diameter (inner diameter) of the cross section of the lumen inside the tube member is a dimension that allows the tube stent 1 to be inserted into the inner sheath of the tube stent delivery device, as described below, and is, for example, approximately 1.0 mm to 5.0 mm.

A distal end through hole (first through hole) 21 is provided at a position (P1 in FIG. 2) where the approximate central axis (C1 in FIG. 2) of the lumen formed in the straight body portion 11 intersects with the peripheral wall of the distal end curved portion 12. More specifically, at a position (P1 in FIG. 2) where the approximate central axis (C1 in FIG. 2) of the lumen formed in the straight body portion 11 intersects with the peripheral wall of the distal end curved portion 12, and on the outer edge side of the curved shape formed by the distal end curved portion 12, an opening that communicates between the inside and outside of the lumen of the distal end curved portion 12 is provided as the distal end through hole 21.

By providing the distal end through hole 21 at the position where the approximate central axis of the lumen in the straight body portion 11 intersects with the peripheral wall of the distal end curved portion 12 in the distal end curved portion 12, the distal end through hole 21 can be positioned at a position where the lumen in the straight body portion 11, which has an approximately linear shape, is extended. As a result, when the tube stent 1 is placed in the bile duct, bile flowing from the bile duct through the distal end through hole 21 can flow smoothly into the lumen in the straight body portion 11.

A proximal end through hole (second through hole) 31 is provided at a position (P2 in FIG. 2) where the approximate central axis (C1 in FIG. 2) of the lumen formed in the straight body portion 11 intersects with the peripheral wall of the proximal end curved portion 13. More specifically, at a position (P2 in FIG. 2) where the approximate central axis (C1 in FIG. 2) of the lumen formed in the straight body portion 11 intersects with the peripheral wall of the proximal end curved portion 13, and on the outer edge side of the curved shape formed by the proximal end curved portion 13, an opening portion that communicates between the inside and outside of the lumen of the proximal end curved portion 13 is provided as the proximal end through hole 31.

By providing the proximal end through hole 31 at the position where the approximate central axis of the lumen in the straight body portion 11 intersects with the peripheral wall of the proximal end curved portion 13 in the proximal end curved portion 13, the proximal end through hole 31 can be positioned at a position where the lumen in the approximately linear straight body portion 11 is extended. As a result, when the tube stent 1 is placed in the bile duct, bile flowing through the lumen in the straight body portion 11 can smoothly flow into the duodenum through the proximal end through hole 31.

The straight body portion 11 has a substantially linear shape, and the distal end through hole 21, the lumen in the straight body portion 11, and the proximal end through hole 31 can be arranged on a substantially linear line. As a result, a substantially linear flow path can be formed via the distal end through hole 21, the lumen in the straight body portion 11, and the proximal end through hole 31. This allows smooth flow of bile into the lumen in the straight body portion 11 via the distal end through hole 21, flow of bile in the lumen in the straight body portion 11, and flow of bile from the lumen in the straight body portion 11 to the duodenum via the proximal end through hole 31 when the tube stent 1 is placed in the bile duct. In order to ensure good and reliable flow of bile from the distal end through hole 21 into the lumen in the straight body portion 11, when the tube stent 1 is placed in the bile duct, for example, the distal end through hole 21 is arranged near the hepatic portal portion located at the back of the bile duct.

The opening area of the distal end through hole 21 and the opening area of the proximal end through hole 31 are preferably set to be larger than the cross-sectional area of the lumen formed in the straight body portion 11. When the tube stent 1 is placed in the bile duct, bile is discharged into the duodenum via a flow path consisting of the distal end through hole 21, the lumen in the straight body portion 11, and the proximal end through hole 31. By making the opening area of the distal end through hole 21 and the opening area of the proximal end through hole 31 larger than the cross-sectional area of the lumen formed in the straight body portion 11, the maximum flow rate of liquid passing through the distal end through hole 21 and the proximal end through hole 31 can be increased relative to the maximum flow rate of liquid in the lumen in the straight body portion 11, and the distal end through hole 21 and the proximal end through hole 31 can be prevented from becoming a bottleneck. As a result, bile flows smoothly through the distal end through-hole 21 and the proximal end through-hole 31 without stagnating.

Furthermore, it is preferable that the distal end through hole 21 and the proximal end through hole 31 are long along the extension direction of the curved tube member. If the dimensions of the distal end through hole 21 and the proximal end through hole 31 are increased along the circumferential direction of the tube member, there is a risk that the strength of the tube member cannot be sufficiently ensured. For example, the circumferential dimensions of the distal end through hole 21 and the proximal end through hole 31 are limited to less than half the circumferential dimension of the entire outer periphery of the tube member.

On the other hand, if the dimensions of the distal end through hole 21 and the proximal end through hole 31 are increased along the extension direction of the tube member, the opening area of the distal end through hole 21 and the opening area of the proximal end through hole 31 can be increased while adequately ensuring the strength of the tube member. Therefore, it is preferable that the distal end through hole 21 and the proximal end through hole 31 are elongated in the extension direction such that the dimension in the extension direction of the tube member is longer than the dimension in the circumferential direction of the tube member.

The distal end through hole 21 and the proximal end through hole 31, in which the dimension in the extension direction of the tube member is longer than the dimension in the circumferential direction of the tube member, can be easily formed, for example, by using a blade or the like to cut off a part of the peripheral wall of the tube member along the extension direction of the tube member so that the internal lumen is exposed.

When forming the distal end through hole 21 and the proximal end through hole 31, a portion of the peripheral wall of the tube member may be cut off as described above, but on the other hand, a portion of the peripheral wall of the tube member may remain connected to the tube member without being cut off.

The distal end through hole 21 is formed by cutting off a portion of the peripheral wall of the tube member that constitutes the distal end curved portion 12, as shown in, for example, Figures 1 and 2.

On the other hand, the proximal end through hole 31 is a cut hole formed by cutting the peripheral wall of the tube member constituting the proximal end curved section 13 toward the straight body section 11 up to the lumen within the tube member, as shown in Figures 1 and 2, for example. Here, when forming the cut hole as the proximal end through hole 31, a part of the peripheral wall of the tube member is not cut off, and the cut piece is left connected to the tube member. The part of the peripheral wall of the tube member that is left uncut near the proximal end through hole 31 (cut piece) can be used, for example, as a flap 32.

The flap 32 has a base end 32a that connects to the tube member at the edge of the proximal end through-hole 31 on the straight body portion 11 side, and a tip end 32b that protrudes from the base end 32a in the opposite direction to the straight body portion 11 side.

The size of the flap 32 can be approximately the same as the size of the part of the tube member separated by the cut made when forming the proximal-end through-hole 31. In addition, the flap 32 is preferably positioned so as not to block the proximal-end through-hole 31 and to ensure a sufficient opening area for the proximal-end through-hole 31. The angle of the flap 32 protruding from the base end 32a to the tip end 32b with respect to the tube member (angle A in FIG. 2) is appropriately set, for example, in the range of 0° to 90°, preferably in the range of 10° to 45°, to realize a shape that protrudes from the base end 32a toward the tip end 32b so as to move away from the proximal-end through-hole 31.

The flap 32 serves as a movement restriction member that restricts the movement (migration) of the tube stent 1 when the tube stent 1 is placed in the bile duct. The flap 32 is provided so as to protrude from the tube member, and even if the proximal end curved portion 13 moves so as to be drawn into the bile duct, the flap 32 interferes (abuts) with the duodenal papilla and the inner wall of the bile duct. In other words, the flap 32 functions as a stopper that prevents the proximal end curved portion 13 from being drawn into the bile duct. As a result, the movement (migration) of the tube stent 1 is restricted, stabilizing the placement state of the tube stent 1.

Furthermore, when the tube stent 1 is placed in the bile duct, the flap 32 is positioned on the upstream side of the duodenum (stomach side) relative to the proximal end through-hole 31, and thus serves as a foreign object intrusion prevention member that prevents foreign objects such as food moving from the upstream side to the downstream side in the duodenum from entering the proximal end through-hole 31.

The tube stent 1 is also provided with an endoscopic marker 41. The endoscopic marker 41 is not particularly limited, but is formed by coloring a part of the outer surface of the tube member in a ring shape, as shown in the figure, for example. The endoscopic marker 41 is preferably provided, for example, near the proximal end through hole 31 of the proximal end curved portion 13. This makes it easy to confirm the positions of the proximal end curved portion 13 and the proximal end through hole 31 of the tube stent 1 under endoscopic images, and allows accurate and easy positioning when placing the tube stent 1 in the bile duct.

Next, a tube stent delivery device for placing a tube stent in a bile duct in an embodiment of the present invention will be described with reference to Figures 3 to 5. Figure 3 is a plan view showing an example of a tube stent delivery device for placing a tube stent in a bile duct in an embodiment of the present invention. Also, Figure 4 is a plan view showing an inner catheter of the tube stent delivery device shown in Figure 3, and Figure 5 is a plan view showing an outer catheter of the tube stent delivery device shown in Figure 3.

The tube stent delivery device 100 shown in FIG. 3 is a medical treatment tool used to place a tube stent 1 in the bile duct, and is an endoscopic device that is inserted into the bile duct via the treatment tool guide tube of an endoscope.

As described above, the tube stent according to the present invention is not limited to a bile duct tube stent that is placed in the bile duct to improve the flow of bile, but may be a pancreatic duct tube stent that is placed in the pancreatic duct to improve the flow of pancreatic juice. Here, as an example, a tube stent delivery device 100 for placing a bile duct tube stent in the bile duct is described, but when the tube stent 1 according to the present invention is a pancreatic duct tube stent, a tube stent delivery device for placement in the pancreatic duct is used. Furthermore, instead of a transendoscopic device that is inserted through the treatment tool guide tube of an endoscope, a percutaneous device that approaches by directly inserting a needle may be used.

The tube stent delivery device 100 shown in FIG. 3 is generally configured to include a long and thin catheter portion 120 that is inserted into the patient's body (lumen) through a treatment tool guide tube of an endoscope (not shown), an operation portion 130 that is connected to the proximal end side of the catheter portion 120 and is used to operate the catheter portion 120 inside the body from outside the body, a guide wire 140, and a tube stent 1 as an object to be placed. In this specification, the tip side of the tube stent delivery device 100 that is inserted into the patient's body is defined as the distal end side of the tube stent delivery device 100, and the base end side where the operator holds and operates the tube stent delivery device 100 outside the patient's body is defined as the proximal end side of the tube stent delivery device 100.

The catheter section 120 comprises an inner sheath (inner tube) 121 having a distal end and a proximal end, and an outer sheath (outer tube) 122 having a distal end and a proximal end. In addition, a contrast marker (not shown) is attached near the distal end of each of the inner sheath 121 and the outer sheath 122. The contrast marker is a position detection marker that can be confirmed by X-ray fluoroscopy when the catheter section 120 is inserted into the patient's body, and is formed from, for example, a metal material such as gold, platinum, or tungsten, or a polymer blended with barium sulfate or bismuth oxide.

The inner sheath 121 is made of a flexible, elongated tube. A guide wire 140 is inserted into the inner cavity of the inner sheath 121 and is used as a guide for inserting the tube stent delivery device 100 into the patient's body. After inserting the guide wire 140 into the body to secure a path between the outside and inside of the body, the catheter portion 120 is advanced along the guide wire 140, so that the distal end of the catheter portion 120 can be inserted into the target site inside the body. The outer diameter of the inner sheath 121 is approximately 0.5 mm to 4.0 mm.

At the distal end of the inner sheath 121, a tip tapered section 123 is formed, which is tapered toward the tip (distal end). Note that instead of the tip tapered section 123, a tip tip having a similar tapered shape may be prepared separately from the inner sheath 121 and attached to the distal end of the inner sheath 121.

The outer sheath 122 is made of a flexible, elongated tube. The outer sheath 122 has an inner diameter slightly larger than the outer diameter of the inner sheath 121, and is inserted inside the outer sheath 122 so that the inner sheath 121 can slide relatively inside the outer sheath 122. For example, the inner diameter of the outer sheath 122 is about 0.5 mm to 4.5 mm, and the outer diameter of the outer sheath 122 is about 1.0 mm to 5.0 mm. The operating unit 130 is connected to the proximal end of the outer sheath 122, and the inner sheath 121 can slide (move relatively) in the axial direction with respect to the outer sheath 122 by the operator operating the connector 131 of the operating unit 130.

Materials that can be used for the inner sheath 121 and the outer sheath 122 include, for example, various resin materials such as polyolefins such as polyethylene and polypropylene, polyesters such as polyvinyl chloride, polyurethane, ethylene-vinyl acetate copolymer, polyethylene terephthalate and polybutylene terephthalate, fluorine-based resins such as polyamide, polyether polyamide, polyester polyamide, polyether ether ketone, polyether imide, polytetrafluoroethylene and tetrafluoroethylene-hexafluoropropylene copolymer, and various thermoplastic elastomers such as polystyrene, polyolefin, polyurethane, polyester, polyamide, and polybutadiene. Two or more of these materials can also be used in combination.

The operating unit 130 includes a connector 131 and a connector 132. As shown in FIG. 4, the connector 131 is connected and fixed to the proximal end of the inner sheath 121. As shown in FIG. 5, the connector 132 is connected and fixed to the proximal end of the outer sheath 122. The connector 131 has a through hole that runs through in the axial direction, and this through hole is connected to the inner cavity of the inner sheath 121. The connector 132 has a through hole that runs through in the axial direction, and this through hole is connected to the inner cavity of the outer sheath 122. The distal end of the connector 131 and the proximal end of the connector 132 can be coupled or uncoupled from each other by a luer lock system or the like.

The guidewire 140 is inserted through the inner cavity of the inner sheath 121 over its entire length. The distal end of the guidewire 140 can protrude from the tapered tip portion 123 of the inner sheath 121, and the proximal end of the guidewire 140 can be exposed to the outside through the through hole of the connector 131.

When the tube stent delivery device 100 is inserted into the patient's body, the tube stent 1 is attached to the distal end side of the tube stent delivery device 100 as shown in FIG. 3. Specifically, the distal end side portion of the inner sheath 121 is inserted inside the tube stent 1, and the proximal end face of the tube stent 1 is abutted against the distal end face of the outer sheath 122 through which the inner sheath 121 is inserted. As a result, the tube stent 1 is arranged in series with the outer sheath 122 with the inner sheath 121 inserted inside it.

As described above, the distal end curved portion 12 and the proximal end curved portion 13 of the tube stent 1 have a curved shape, but when the tube stent 1 is attached to the distal end side of the tube stent delivery device 100, the distal end curved portion 12 and the proximal end curved portion 13 are elastically deformed into an approximately linear shape to match the shape of the inner sheath 121.

When placing the tube stent 1 in the bile duct, first, the guide wire 140 is inserted into the bile duct through the treatment tool guide tube of the endoscope. Next, the connectors 131 and 132 are joined to each other, and the catheter portion 120 is advanced along the guide wire 140 with the tube stent 1 attached to the distal end side of the inner sheath 121.

The tube stent 1 is inserted to an appropriate position in the bile duct while checking the positions of the inner sheath 121 and the outer sheath 122 by X-ray fluoroscopy. The connectors 131 and 132 are then released from the connection, and the inner sheath 121 and the guide wire 140 are slid toward the proximal end and pulled out while leaving the outer sheath 122 in its original position, and then the outer sheath 122 is pulled out, allowing the tube stent 1 to be placed in the bile duct, as shown, for example, in FIG. 6 or FIG. 7.

Figure 6 is a schematic diagram showing a state in which a tube stent according to an embodiment of the present invention is placed in a bile duct. Figure 6 is a schematic diagram showing a cross section of the inside of a body, and Figure 6 shows the duodenum 61, duodenal papilla 62, common bile duct 63, gallbladder duct 64, stenosis 65, pancreatic duct 66, common hepatic duct 67, hepatic portal 68, right intrahepatic bile duct 69, and left intrahepatic bile duct 70. The gallbladder duct 64 is connected to a gallbladder (not shown), and the pancreatic duct 66 is connected to a pancreas (not shown).

For example, if a stenosis 65 occurs in the common bile duct 63 due to a tumorous lesion or the like, the stenosis 65 may block the common bile duct 63 and inhibit the flow of bile. The tube stent 1 is a medical device that is placed in the stenosis 65 of the common bile duct 63 to improve the flow of bile, and is placed as shown in FIG. 6 as an example.

In the tube stent 1 shown in FIG. 6, the straight body portion 11 is positioned near a stenosis 65 that has occurred in the common bile duct 63. As a result, a bile flow path is secured through the lumen in the straight body portion 11 in the common bile duct 63 that was blocked by the stenosis 65.

In the tube stent 1 shown in FIG. 6, the curved distal end curved portion 12 is disposed near the hepatic portal portion 68. More specifically, a distal end through hole 21 having an opening area larger than the cross-sectional area of the lumen in the straight body portion 11 is disposed near the hepatic portal portion 68. This allows bile to flow smoothly and reliably from the distal end through hole 21 disposed near the hepatic portal portion 68 into the lumen in the straight body portion 11.

The distal curved portion 12 has a curved shape, and is arranged to be spread out so that a part of the distal curved portion 12 is pressed against the inner wall of the common bile duct 63 due to the elastic force that tries to return to its natural state. As a result, the distal curved portion 12 interferes with (abuts against) the inner wall of the common bile duct 63, restricting the movement (migration) of the tube stent 1, and the placement state of the tube stent 1 can be stabilized.

In the tube stent 1 shown in FIG. 6, the proximal end curved portion 13 having a curved shape is disposed in the duodenum 61. In addition, the proximal end curved portion 13 is disposed with a proximal end through hole 31 having an opening area larger than the cross-sectional area of the lumen formed in the straight body portion 11. This allows bile flowing through the lumen in the straight body portion 11 to flow smoothly and reliably from the proximal end through hole 31 into the duodenum 61.

The proximal curved portion 13 is designed to have a smaller curved shape than the distal curved portion 12, so that it can be reliably curved in the duodenum 61. This curved shape prevents the proximal end face of the tube member constituting the proximal curved portion 13 from hitting the inner wall of the duodenum 61, preventing ulcers or perforations from occurring in the inner wall. This curved shape also makes it difficult for the proximal curved portion 13 to be drawn into the common bile duct 63, which restricts the movement (migration) of the tube stent 1 and stabilizes the placement state of the tube stent 1.

As described above, in the tube stent 1 according to the present invention, the distal end through-hole 21, the lumen in the straight body portion 11, and the proximal end through-hole 31 are arranged in a substantially straight line, and a substantially linear flow path is formed via the distal end through-hole 21, the lumen in the straight body portion 11, and the proximal end through-hole 31. Furthermore, in the tube stent 1 shown in FIG. 6, the distal end through-hole 21 is arranged near the hepatic portal portion 68. This allows bile to flow smoothly into the lumen in the straight body portion 11 via the distal end through-hole 21 arranged near the hepatic portal portion 68, bile to flow in the lumen in the straight body portion 11, and bile to flow smoothly from the lumen in the straight body portion 11 to the duodenum 61 via the proximal end through-hole 31.

In the tube stent 1 shown in FIG. 6, the flap 32 formed near the proximal end through hole 31 is disposed in the duodenum 61. Even if the proximal end curved portion 13 moves to be drawn into the common bile duct 63, the flap 32 interferes with (abuts against) the duodenal papilla 62 and the inner wall of the common bile duct 63, and serves as a stopper to prevent the proximal end curved portion 13 from being drawn into the common bile duct 63. As a result, the movement (migration) of the tube stent 1 is restricted, and the placement state of the tube stent 1 can be stabilized.

Furthermore, as shown in FIG. 6, when the tube stent 1 is placed in the bile duct, it is preferable that the flap 32 is disposed on the upstream side of the duodenum (stomach side) with respect to the proximal end through-hole 31. As described above, the flap 32 serves as a foreign object intrusion prevention member, and by disposing the flap 32 on the upstream side of the duodenum (stomach side) with respect to the proximal end through-hole 31, it is possible to prevent foreign objects such as food moving from the upstream side to the downstream side in the duodenum 61 from entering the proximal end through-hole 31.

Figure 7 is a schematic diagram showing another state in which a tube stent according to an embodiment of the present invention is placed in a bile duct. Figure 7 is a schematic diagram showing a cross section of the inside of a body, and like Figure 6, Figure 7 also shows the duodenum 61, duodenal papilla 62, common bile duct 63, cystic duct 64, stenosis 65, pancreatic duct 66, common hepatic duct 67, hepatic hilum 68, right intrahepatic bile duct 69, and left intrahepatic bile duct 70.

When the tube stent 1 is placed in the patient's body using the tube stent delivery device 100, the distal curved portion 12 does not necessarily have a curved shape as shown in FIG. 6, and may be arranged to extend distally from the hepatic portal 68 (e.g., into the left intrahepatic bile duct 70) as shown in FIG. 7. Even in such an arrangement, the distal through-hole 21 is arranged near the hepatic portal 68, and bile flows smoothly into the lumen in the straight body portion 11 via the distal through-hole 21 arranged near the hepatic portal 68, bile flows in the lumen in the straight body portion 11, and bile flows out of the lumen in the straight body portion 11 to the duodenum 61 via the proximal through-hole 31.

Next, we will explain how it works.

The tube stent 1 in this embodiment is made of a flexible tube member and is composed of a straight body portion 11 having an approximately straight shape, a distal end curved portion 12 having a curved shape connected to one end of the straight body portion 11, and a proximal end curved portion 13 having a curved shape connected to the other end of the straight body portion 11. A distal end through hole 21 is provided at a position where the approximate central axis of the lumen formed in the straight body portion 11 intersects with the peripheral wall of the distal end curved portion 12, and a proximal end through hole 31 is provided at a position where the approximate central axis of the lumen formed in the straight body portion 11 intersects with the peripheral wall of the proximal end curved portion 13.

This configuration allows the distal end through hole 21, the lumen in the straight body portion 11, and the proximal end through hole 31 to be arranged in a substantially straight line, forming a substantially straight flow path, allowing bile to flow into the distal end through hole 21 and out of the proximal end through hole 31 satisfactorily and reliably. In particular, it is possible to achieve an exceptionally good bile flow compared to conventional tube stents (see, for example, Patent Documents 1 and 2) in which the distal end through hole 21, the lumen in the straight body portion 11, and the proximal end through hole 31 are not arranged to form a substantially straight line.

In the present embodiment, the tube stent 1 is made of a flexible tube member, and both end faces (distal end face and proximal end face) of the tube member are open. However, the inventors have confirmed through extensive research that when the tube stent 1 is placed in the bile duct, the distal end through-hole 21, the lumen in the straight body portion 11, and the proximal end through-hole 31 become the main flow paths for bile, so that bile hardly flows through the openings at both end faces of the tube member, and both end faces of the tube member hardly function as flow paths. For this reason, both end faces of the tube member constituting the tube stent 1 may be open or closed.

In addition, in the tube stent 1 of this embodiment, the distal end through hole 21 is provided on the outer edge side of the curved shape of the distal end curved portion 12, and the proximal end through hole 31 is provided on the outer edge side of the curved shape of the proximal end curved portion 13.

This configuration allows a distal end through hole 21 to be provided at a position on the peripheral wall of the distal end curved portion 12 that intersects with the axial direction of the straight body portion 11, and a proximal end through hole 31 to be provided at a position on the peripheral wall of the proximal end curved portion 13 that intersects with the axial direction of the straight body portion 11.

In addition, in the tube stent 1 of this embodiment, the distal end through hole 21 and the proximal end through hole 31 are formed to have an opening area larger than the cross-sectional area of the lumen in the straight body portion 11.

This configuration makes it possible to increase the maximum flow rate of liquid passing through the distal end through hole 21 and the proximal end through hole 31 relative to the maximum flow rate of liquid in the lumen in the straight body portion 11, thereby preventing the distal end through hole 21 and the proximal end through hole 31 from becoming a bottleneck.

In addition, in the tube stent 1 of this embodiment, the distal end through hole 21 is long along the extension direction of the tube member constituting the distal end curved section 12, and the proximal end through hole 31 is long along the extension direction of the tube member constituting the proximal end curved section 13.

This configuration allows the distal end through hole 21 and the proximal end through hole 31 to be formed with the desired opening area while maintaining sufficient strength of the tube stent 1. In addition, the distal end through hole 21 and the proximal end through hole 31 can be formed by cutting the distal end curved portion 12 and the proximal end curved portion 13 with a blade or the like along the extension direction of the tube member, making it easy to manufacture the tube stent 1.

In addition, in the tube stent 1 of this embodiment, a cut hole in the peripheral wall of the proximal end curved portion 13 toward the straight body portion 11 is used as the proximal end through hole 31, and a flap 32 is provided having a base end 32a that connects to the tube member on the straight body portion 11 side of the cut hole, and a tip end 32b that protrudes from the base end 32a to the side opposite the straight body portion 11.

With this configuration, the incision that forms the proximal-end through-hole 31 allows a flap 32 to be formed near the proximal-end through-hole 31. This flap 32 serves as a movement restriction member that restricts the movement (migration) of the tube stent 1, and also serves as a foreign object intrusion prevention member that prevents foreign objects from entering the proximal-end through-hole 31.

In addition, in the tube stent 1 of this embodiment, the flap 32 has a shape that protrudes from the base end 32a toward the tip end 32b, away from the proximal end through-hole 31.

This configuration allows the flap 32 to interfere (contact) with the duodenal papilla or the inner wall of the bile duct as a movement restriction member, and to prevent foreign matter from entering the proximal end through-hole 31 as a foreign matter entry prevention member.

In addition, in the tube stent 1 of this embodiment, the radius of curvature of the curved shape of the proximal end curved portion 13 is set to be smaller than the radius of curvature of the curved shape of the distal end curved portion 12.

With this configuration, when the tube stent 1 is placed in the bile duct, the proximal end curved portion 13 is reliably curved in the duodenum, and the proximal end face of the tube stent 1 does not abut against the inner wall of the duodenum.

In addition, in the tube stent 1 of this embodiment, an endoscopic marker 41 may be provided near the proximal end through-hole 31 of the proximal end curved portion 13.

This configuration makes it easy to confirm the positions of the second curved portion and the second through hole of the tube stent 1 under endoscopic images, and makes it easy to confirm the positions of the proximal end curved portion 13 and the proximal end through hole 31 of the tube stent 1, making it possible to accurately and easily position the tube stent 1 when placing it in the bile duct.

As described above, the tube stent according to the present invention has the effect of realizing an appropriate patency state with a simple configuration and enabling good and reliable discharge of bile or pancreatic juice into the duodenum, and is useful as a bile duct tube stent or pancreatic duct tube stent used for improving the flow of bile or pancreatic juice by being placed in the narrowed portion of the bile duct or pancreatic duct.

The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to these examples.

(composition)
The bottom of the beaker was opened and a valve was attached to it. Processed tubes were attached to the top and bottom of the valve, so that the communication between the top and bottom could be controlled by opening and closing the valve.

Additionally, multiple tubes made of polyamide elastomer (product name: Pebax) with a diameter of 7.5 Fr (2.5 mm) and a length of 10 cm were prepared as tubes to be attached to the valves, and were processed and molded into the following shapes to produce tubes A to D.
Tube A (see FIG. 8(a)): a tube with a straight shape; Tube B (see FIG. 8(b)): a tube formed into a pigtail shape with multiple small holes formed in a direction perpendicular to the curved surface of the pigtail; Tube C (see FIG. 8(c)): a tube formed into a pigtail shape with a large through-hole formed in the axial direction of the straight body; Tube D (see FIG. 8(d)): a tube formed into a pigtail shape with a large through-hole formed by cutting a notch in the axial direction of the straight body, and with the cut piece left intact to form a flap. Tube C has a configuration corresponding to the distal end curved portion 12 in the above-mentioned embodiment, and Tube D has a configuration corresponding to the proximal end curved portion 13 in the above-mentioned embodiment.

Example 1
A solution of 5% bile acid, 5% oleic acid, and 0.5% Echogum/Ketolol was mixed to prepare a simulated bile with the same viscosity as bile, and heated to about 40° C. A predetermined amount of simulated bile was placed in a beaker with tube A attached to the top of the valve and tube D attached to the bottom of the valve, with the valve closed (see FIG. 9(a)). After that, the simulated bile that naturally dripped from the tube attached to the bottom of the valve was collected with the valve open for 60 seconds, and its weight (to the nearest 0.1 g) was measured. The measurement results are shown in Table 1.

Example 2
The same procedure as in Example 1 was carried out except that the tube attached to the upper part of the valve was changed to tube C and the tube attached to the lower part of the valve was changed to tube A (see FIG. 9(c)). The simulated bile that naturally dripped from the tube attached to the lower part of the valve was collected and its weight (to the nearest 0.1 g) was measured. The measurement results are shown in Table 1.

(Comparative Example 1)
The same procedure as in Example 1 was carried out except that the tube attached to the lower part of the valve was changed to tube B (see FIG. 9(b)), and the artificial bile that naturally dripped from the tube attached to the lower part of the valve was collected and its weight (to the nearest 0.1 g) was measured. The measurement results are shown in Table 1.

(Comparative Example 2)
The same procedure as in Example 2 was carried out except that the tube attached to the upper part of the valve was changed to tube B (see FIG. 9(d)), and the artificial bile that naturally dripped from the tube attached to the lower part of the valve was collected and its weight (to the nearest 0.1 g) was measured. The measurement results are shown in Table 1.

From Table 1, it can be seen that the configuration in which tube C is attached to the top of the valve provides a significantly higher flow rate than the configuration in which tube B is attached to the top of the valve (comparison between Example 2 and Comparative Example 2). Tube C corresponds to the distal curved portion 12 in the above-mentioned embodiment, and even if it has a similar pigtail shape, a significantly better patency is achieved by controlling the position of the opening hole.

Also, from Table 1, it can be seen that the configuration in which tube D is attached to the lower part of the valve provides a significantly higher flow rate than the configuration in which tube B is attached to the lower part of the valve (comparison between Example 1 and Comparative Example 1). Tube D is a configuration that corresponds to the proximal end curved portion 13 in the above-mentioned embodiment, and even if it has a similar pigtail shape, a significantly better open state is achieved by controlling the position of the opening hole.

LIST OF SYMBOLS 1 Tube stent 11 Straight body portion 12 Distal end curved portion 13 Proximal end curved portion 21 Distal end through hole 31 Proximal end through hole 32 Flap 32a Base end portion 32b Tip portion 41 Endoscope marker 61 Duodenum 62 Duodenal papilla 63 Common bile duct 64 Gallbladder duct 65 Stenosis portion 66 Pancreatic duct 67 Common hepatic duct 68 Portion of the liver 69 Right intrahepatic bile duct 70 Left intrahepatic bile duct 100 Tube stent delivery device 120 Catheter portion 121 Inner sheath 122 Outer sheath 123 Tip tapered portion 130 Operation portion 131, 132 Connector 140 Guidewire

Claims (8)

A tube stent comprising a flexible tubular member,
A straight body portion having a substantially straight line shape;
A first curved portion having a curved shape connected to one end of the straight body portion;
A second curved portion having a curved shape connected to the other end of the straight body portion;
It is composed of
a first through hole is provided at a position where an approximate central axis of a lumen formed in the straight body portion intersects with a peripheral wall of the first curved portion;
a second through hole is provided at a position where an approximate central axis of a lumen formed in the straight body portion intersects with a peripheral wall of the second curved portion ;
The second through hole is a cut hole formed by cutting a peripheral wall of the second curved portion toward the straight body portion,
A tube stent characterized in that it is provided with a flap having a base end portion connected to the tube member on the straight body side of the cut hole, and a tip end portion protruding from the base end portion on the opposite side to the straight body portion. The first through hole is provided on an outer edge side of the curved shape of the first curved portion,
The tube stent according to claim 1, characterized in that the second through-hole is provided on the outer edge side of the curved shape of the second curved portion. The tube stent according to claim 1 or 2, characterized in that the first through hole and the second through hole have an opening area larger than the cross-sectional area of the lumen formed in the straight body portion. A tube stent according to any one of claims 1 to 3, characterized in that the first through-hole is elongated along the extension direction of the tube member constituting the first curved section, and the second through-hole is elongated along the extension direction of the tube member constituting the second curved section. 5. The tube stent according to claim 1 , wherein the flap has a shape that protrudes from the base end toward the tip end so as to move away from the cut hole. 6. The tube stent according to claim 1, wherein the radius of curvature of the curved shape of the second curved portion is smaller than the radius of curvature of the curved shape of the first curved portion. The tube stent according to any one of claims 1 to 6 , characterized in that an endoscopic marker is provided in the vicinity of the second through-hole of the second curved portion. 8. The tube stent according to claim 1, which is used as a bile duct tube stent or a pancreatic duct tube stent.