Tube Stent

Abstract

To provide a tube stent capable of discharging bodily fluids through a gap between the stent body and a body lumen even if the lumen of the stent body is closed. [Solution] The tube stent 1 is a tubular stent to be placed in a lumen of the body, and comprises a resin stent body 2 having an inner lumen 20 defined by an inner surface 21 along the longitudinal direction, and the stent body 2 has grooves 23 (external flow paths) formed along its entire length so that when the tube stent 1 is placed in the lumen, bodily fluids from the body can flow along the longitudinal direction outside the outer surface 22 of the stent body 2.

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, stents have been placed in order to expand narrowed areas formed in the lumens of the body, such as the bile duct and pancreatic duct, and to maintain an open state.

[0003] Stents are used in procedures such as endoscopic retrograde biliary drainage (ERBD). ERBD is a treatment method in which a drainage tube is inserted from the duodenal papilla to the bile duct using an endoscope to maintain the outflow of bile. A resin stent or a metal stent is inserted into the site of the bile duct blocked by gallstones or cancer to improve the flow of bile, a digestive fluid. Compared to metal stents, resin stents have a smaller lumen diameter and are therefore more likely to become blocked, but they are easily removed and have therefore been widely used in recent years.

[0004] Known examples of resin stents include the one described in Patent Document 1. The stent described in Patent Document 1 is a bile duct tube stent made of a resin material, and the tube stent has spiral or annular grooves along the circumferential direction on at least a part of its outer surface, with the groove depth being 1.3 to 5.5% (e.g., 0.015 mm) of the wall thickness of the tube stent and the groove pitch being 0.04 mm or more and 1.0 mm or less, which is said to be capable of suppressing the occurrence of kinking even when used in a bent state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-121577 A Summary of the Invention [Problem to be solved by the invention]

[0006] According to the above-mentioned conventional example, when the lumen of the tube stent is blocked, it is difficult to drain bodily fluids from the body through the grooves because the depth of the grooves on the outer surface is small.

[0007] An object of the present invention is to provide a tube stent which is capable of discharging bodily fluids through a gap between the stent body and the body lumen even if the lumen of the stent body is closed. [Means for solving the problem]

[0008] [1] A tubular stent to be placed in a lumen of the body, The inner cavity is defined by an inner circumferential surface. As the main discharge route The stent body is made of resin and extends in the longitudinal direction. The stent body is configured such that, when the tube stent is placed in the lumen, bodily fluid from the body can flow along the longitudinal direction outside the outer circumferential surface of the stent body. Multiple External flow path As multiple sub-emission routes Formed along the entire length Cage , The plurality of external flow paths are a plurality of grooves formed by partially thinning the wall thickness of the stent body, a volume of the plurality of sub discharge routes is substantially equal to a volume of the main discharge route; The stent body includes a reinforcing layer over the entire length thereof, the minimum thickness of the stent body at the groove is 0.05 mm or more and 0.50 mm or less; When the tube stent is placed in the lumen and the cross-sectional area of ​​the main discharge route is reduced due to the tube stent being deformed in the radial direction or the main discharge route being blocked, at least one of the sub discharge routes can be secured. Tube stent. [ 2 the stent body comprises an inner layer having the lumen on the inside thereof, and an outer layer provided outside the inner layer and having the plurality of grooves formed on the outer circumferential surface side; The reinforcing layer is formed between the inner layer and the outer layer. 1 ] A tube stent as described in the above. [ 3 ] The reinforcing layer is configured to include a coil body formed by helically winding a linear member, or a braided body formed by braiding the linear member. 2 ] A tube stent as described in the above. [4] The plurality of grooves are two or more and five or less grooves formed at equal intervals in the circumferential direction. 1 ] A tube stent as described in the above. [5] A tube stent as described in [4], wherein the multiple grooves are formed parallel to the axial direction of the inner lumen. [6] A tube stent as described in [4], wherein the plurality of grooves are formed in a spiral shape. [ 7 ] A tube stent as described in [5] or [6], wherein when Vs is the volume over the entire length between a circle circumscribing the protrusion of the thick-walled portion formed by partially thinning the wall thickness of the stent body and one groove, and Vm is the volume over the entire length of the inner lumen, the following relationship is satisfied: NVs = kVm (where N is the number of grooves and k is 0.8 to 1.2). [ 8 ] A tube stent as described in [5] or [6], wherein the ratio of the depth of the groove to the inner diameter of the lumen is 0.025 or more and 0.55 or less. Effect of the Invention

[0009] According to the present invention, even if the lumen of the stent body is closed, bodily fluids can be discharged through the gap between the lumen and the body lumen. [Brief description of the drawings]

[0010] [Figure 1] 1(a) to (d) are front views of a tube stent according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Diagram 3] Figure 3(a) is a left side view of the tube stent in Figure 1(a) seen from the tip side, Figure 3(b) is a longitudinal cross-sectional view of Figure 3(a), and Figure 3(c) is a longitudinal cross-sectional view of a key portion showing a modified example of the shape of the end portion. [Figure 4] FIG. 4 is a diagram showing an example of a method of using the tube stent according to the first embodiment. [Diagram 5]FIG. 5 is a diagram showing an example of a method of using the tube stent according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view corresponding to FIG. 2 of a tube stent according to a second embodiment of the present invention. [Figure 7A] FIG. 7A shows an Amsterdam-type tube stent according to a third embodiment of the present invention, where (a) is a left side view seen from the distal end side, and (b) is a longitudinal sectional view of a main portion. [Figure 7B] FIG. 7B shows a Tanenbaum-type tube stent according to a third embodiment of the present invention, where (a) is a left side view seen from the distal end side, and (b) is a front view of a main portion. [Figure 8] FIG. 8 is a schematic diagram of an experimental model for evaluating the drainage capacity. [Figure 9] FIG. 9 is a photograph showing the results of an experiment conducted using the experimental model shown in FIG. [Figure 10] FIG. 10 is a photograph showing the results of an experiment conducted using the experimental model shown in FIG. [Figure 11] FIG. 11 is a photograph showing a cross section of a tube stent placed in a stenosed simulated lumen. [Figure 12] FIG. 12 is a photograph showing an experimental example for evaluating kink resistance with and without a reinforcing layer. [Figure 13] 13(a) and 13(b) are perspective views of the essential parts showing modified examples 3 and 4 of the groove, respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, components having substantially the same functions are given the same reference numerals and their repeated explanations will be omitted. In this specification, the side inserted into the body is called the distal end side, and the side operated by the surgeon is called the proximal end side.

[0012] [First embodiment] Figures 1(a) to (d) are front views of a tube stent according to a first embodiment of the present invention. Figure 2 is a cross-sectional view taken along line AA in Figure 1(a). Figure 3(a) is a left side view of the tube stent in Figure 1(a) seen from the tip side, Figure 3(b) is a longitudinal cross-sectional view of Figure 3(a), and Figure 3(c) is a longitudinal cross-sectional view of a main part showing a modified shape of an end portion.

[0013] The tube stent 1 is placed in a body lumen (bile duct, pancreatic duct, ureter, etc.) and has an overall tubular shape. The tube stent 1 includes a resin stent body 2 having a lumen 20 in the longitudinal direction defined by an inner circumferential surface 21. The cross-sectional shape of the inner circumferential surface 21 is, for example, circular, but may be other shapes such as an ellipse.

[0014] The tube stent 1 has a length (e.g., 30 mm, 80 mm, 150 mm, etc.) according to the site in the body lumen where it is to be placed. A plurality of tube stents 1 of different lengths may be prepared in advance, and when placing the tube stent 1 in the lumen, a tube stent 1 of an appropriate length may be selected according to the site where it is to be placed.

[0015] Stents include resin stents with a relatively small lumen and metal stents with a relatively large lumen, and these are used differently depending on the condition, etc., even if the lumen in which they are placed is the same. For example, commercially available resin stents have an outer diameter of 7 Fr (2.33 mm) to 12 Fr (4.00 mm). When a stent is placed in a lumen (for example, the bile duct), the lumen of the stent becomes blocked after a certain period of time (about 5 months at most for a resin stent). This is thought to be because dietary fiber and intestinal bacteria flowing through the duodenum flow back into the stent, and bacterial solid matter is generated and accumulated in the lumen of the stent, causing the lumen of the stent to become blocked. Even if the lumen of the stent (main discharge route) is blocked, if there is a sub-discharge route, it is expected that the stent will be placed for a longer period of time. Therefore, in this embodiment, a sub-discharge route is formed between the outer circumferential surface 22 of the tube stent 1 and the inner wall of the lumen of the body.

[0016] In the stent body 2 of this embodiment, grooves 23 are formed on the outside of the outer circumferential surface 22 over the entire length so that bodily fluids from the body can flow along the longitudinal direction outside the outer circumferential surface 22 of the stent body 2 when the tube stent 1 is placed in a body lumen. The grooves 23 are formed, for example, by partially thinning the wall thickness of the stent body 2. When the tube stent 1 is placed in a body lumen, the space between the grooves 23 and the inner wall of the body lumen becomes a secondary discharge route. The grooves 23 are an example of an external flow path.

[0017] Specifically, as shown in FIG. 2, the stent body 2 has a plurality of (for example, four) grooves 23 formed on the outer peripheral surface 22 at equal intervals in the circumferential direction, and a plurality of (for example, four) protrusions 24 formed between the grooves 23. The plurality of protrusions 24 are circumscribed by a circle (circumscribed circle) 22a having a diameter D1, for example. The four grooves 23 are inscribed by a circle (inscribed circle) 22b having a diameter D2, for example. The depth h of the groove 23 can be defined as h=(D1-D2) / 2. The protrusions 24 are thick-walled portions formed by partially thinning the wall thickness of the stent body 2. By forming a plurality of protrusions 24 on the outer peripheral surface 22, it is possible to increase the bending rigidity (kink resistance) that makes it difficult for kinking to occur when the tube stent 1 is placed in a curved lumen. The number of grooves 23 and protrusions 24 is not limited to four, and may be one, two, three, or five or more. In particular, by forming two to five grooves 23 and protrusions 24 at equal intervals in the circumferential direction, even if some of the sub-discharge routes cannot be secured due to compression caused by infiltration of a tumor or the like from one of the four sides, it is possible to secure at least one sub-discharge route.

[0018] The diameter d of the cavity 20 may be, for example, 0.80 mm or more and 2.00 mm or less. The wall thickness t of the groove 23 may be, for example, 0.05 mm or more and 0.50 mm or less. The depth h of the groove 23 may be, for example, 0.30 mm or more and 0.60 mm or less. The maximum outer diameter (diameter D1) of the outer circumferential surface 22 may be, for example, 1.50 mm or more and 3.20 mm or less.

[0019] The outer shape of the stent body 2 is, for example, as shown in FIG. 2, an outer shape in which a circumscribing circle 22a circumscribes the entire outer circumferential surface 22 of the four protrusions 24, that is, a shape in which a groove 23 is formed on the outside of a concentric tubular member, so that the tube stent 1 can be placed in a gentle manner in a lumen of the body. In addition, the corner 24a where the outer circumferential surface 22 of the protrusion 24 and the outer circumferential surface 22 of the groove 23 intersect is rounded as shown in FIG. 2. In addition, the corner 24b between the protrusion 24 and the distal end surface 2a and the proximal end surface 2b is rounded as shown in FIG. 3(b). In addition, the corner 24c between the outer circumferential surface 22 of the protrusion 24 and the distal end surface 2a may be tapered as shown in FIG. 3(c). In addition, the corner between the outer circumferential surface 22 of the protrusion 24 and the proximal end surface 2b may be tapered like the distal end surface 2a side, or may be rounded like the corner 24b shown in FIG. 2.

[0020] (Configuration of Grooves and Protrusions) The grooves 23 and the protrusions 24 may be formed parallel to the axial direction of the lumen 20 as shown in FIG. 1(a), or may be formed in a spiral shape as shown in FIG. 1(b) to (d). In FIG. 1(b), the spiral pitch p of the grooves 23 is 45 mm, in FIG. 1(c), the spiral pitch p is 11.5 mm, and in FIG. 1(d), the spiral pitch p is 4.5 mm. The grooves 23 and the protrusions 24 are formed in a spiral shape with a smaller spiral pitch than those formed in parallel to the axial direction of the lumen 20, so that the external flow path 25 formed by the grooves 23 is less likely to be blocked by a narrowed portion. In addition, by forming the grooves 23 in a spiral shape, the volume of the sub-drainage route can be increased, and there is an effect that drainage becomes easier. That is, the spiral pitch p of the grooves 23 is preferably 50 mm or less, more preferably 10 mm or less or 5 mm or less. From the viewpoint of ease of manufacture, the spiral pitch p of the groove 23 is preferably equal to or greater than 2 mm, and more preferably equal to or greater than 4.5 mm.

[0021] 2, the cross-sectional shape of the groove 23 is a semicircle with a radius of about 0.2 to 0.4 mm, but may be other shapes such as an ellipse or a U-shape. From the viewpoint that the sub-discharge route takes the place of the main discharge route when the main discharge route is blocked, when the volume of one sub-discharge route, i.e., the volume over the entire length between the circumscribing circle 22a circumscribing the protrusion 24 and one groove 23, is Vs, and the volume of the main discharge route, i.e., the volume over the entire length of the lumen 20, is Vm, the following relational formula (1) may be satisfied. NVs = kVm (where N is the number of grooves 23, k = 0.8 to 1.2) (1) The volume Vs of the sub discharge route is calculated by multiplying the cross-sectional area As between the circumscribing circle 22a and the groove 23 by the total length Lout of the groove 23.

[0022] In order to ensure at least one sub-exhaust route when the tube stent 1 is placed in a curved lumen or when some sub-exhaust routes cannot be ensured due to infiltration by a tumor or the like, it is preferable that the depth h of the groove 23 has a certain size relative to the diameter d of the lumen 20. The relative size of the groove 23 to the diameter d of the lumen 20 can be determined by the ratio (h / d) of the depth h (=D1-D2) / 2 of the groove 23 to the diameter d of the lumen 20. The ratio (h / d) is preferably, for example, 0.025 or more and 0.55 or less.

[0023] (Material for forming the stent body) The stent body 2 may be made of a resin material (e.g., polyamide, polyurethane, polyethylene, silicone rubber, fluororesin, etc.) having elasticity such as flexibility to bend along the intrusion path and expandability in the radial direction. The stent body 2 may be made of a thermoplastic resin or a thermosetting resin. The stent body 2 is preferably coated with a material to which bodily fluids do not easily adhere (e.g., a coating material having high biocompatibility such as MPC, PMMA, etc.) at least on the inner circumferential surface 21 and the outer circumferential surface 22. Since bodily fluids mainly flow through the lumen 20, only the surface of the inner circumferential surface 21 may be coated with a material to which bodily fluids do not easily adhere. The outer circumferential surface 22 of the stent body 2 may be coated with a hydrophilic coating. This reduces the friction coefficient of the surface of the tube stent 1, making it easier to insert the tube stent 1 into the lumen of the body, and is expected to prevent adhesion of proteins and crystal components.

[0024] In order to make it easier to confirm the position of the tip of the tube stent 1 under X-ray photography, the stent body 2 may be formed by mixing a contrast agent (barium sulfate, bismuth oxide, tungsten, etc.) into the material forming the stent body 2. A marker made of a metal having X-ray contrast (e.g., gold, tantalum, platinum-iridium alloy, tungsten, etc.) may be provided on the tip side of the stent body 2. The marker may be provided on the base end side, or in the case of a tube stent equipped with a flap or pigtail, it may be provided closer to the center than the flap or pigtail.

[0025] (How to use) An example of a method of using the tube stent 1 of this embodiment will be described with reference to Figures 4 and 5. Figure 4 is a diagram showing the tube stent 1 being inserted into the bile duct by endoscopic retrograde biliary drainage (ERBD), and Figure 5 is a diagram showing the tube stent 1 placed in the narrowed portion of the bile duct.

[0026] First, a user such as a surgeon inserts the endoscope insertion portion 100 into a body cavity from the patient's mouth or the like, and advances the tip portion 101 of the endoscope insertion portion 100 through the duodenum 200 to the vicinity of the duodenal papilla 201, as shown in FIG.

[0027] Next, the user inserts the guidewire 110 into the channel of the endoscope and projects the tip of the guidewire 110 from the opening 101a of the tip portion 101 toward the duodenal papilla 201. Then, the tip of the guidewire 110 is inserted from the duodenal papilla 201 into the bile duct 202. Here, the bile duct 202 is an example of a lumen of the body.

[0028] Next, the user checks the shapes of the duodenal papilla 201 and the narrowed portion 202a of the bile duct 202 under X-ray fluoroscopy, and selects a tube stent 1 with an appropriate length. In other words, the user selects a tube stent 1 having a length from the duodenal papilla 201 to a position beyond the narrowed portion 202a of the bile duct 202.

[0029] Next, the user inserts a stent delivery catheter (not shown) with the selected tube stent 1 attached to the outside into the channel of the endoscope and advances it along the guide wire 110. Then, the tip of the stent delivery catheter is inserted into the bile duct 202 from the duodenal papilla 201, and the tube stent 1 advances into the bile duct 202 as shown in FIG.

[0030] Next, as shown in Fig. 5, when the tip of the tube stent 1 reaches a position beyond the narrowed portion 202a of the bile duct 202, the tube stent 1 is placed there. The tube stent 1 expands in the radial direction due to its own expandability, widening the narrowed portion 202a in the radial direction. This makes it possible to secure a flow path for bodily fluids.

[0031] Although endoscopic retrograde biliary drainage (ERBD) has been described above as a procedure, the present invention may be applied to other drainage procedures such as endoscopic pancreatic stenting (EPS).

[0032] The present invention is not limited to the bile duct, but can also be applied to other lumens such as the pancreatic duct and the ureter. Here, the pancreatic duct and the ureter are examples of lumens in the body. For example, the present invention may be applied to a ureteral stent as a tubular medical tube that helps transport urine from the kidney to the bladder. Possible uses of a ureteral stent include, for example, the following: To prevent blockage of the ureter by debris after crushing kidney stones. To prevent post-operative swelling of the ureter following kidney stone removal. For the treatment of ureteral obstruction due to blood clots, scar tissue, ureteral stones, and inflammatory bowel disease.

[0033] (Effects of the First Embodiment) According to this embodiment, the following effects are obtained. (a) In addition to using the inner lumen 20, which is similar to that of existing resin stents, as the main discharge route, an auxiliary sub-discharge route is provided along the groove 23. Therefore, even if the inner lumen 20 becomes blocked, it is expected that bodily fluids will be discharged through the sub-discharge route. (b) If the lumen course of the tube stent 1 changes due to pressure from a tumor or organ atrophy, etc., and the tube stent 1 is deformed radially, the presence of grooves 23 between the protrusions 24 makes it easy for gaps to remain between the inner wall of the body lumen and the grooves 23. (c) The tube stent 1 may have a plurality of side holes formed in one or both of the distal end and proximal end areas that penetrate the wall of the stent body 2. This allows bodily fluids to flow in and out through the side holes, which is expected to improve the drainage effect. (d) By forming a groove structure on the outer circumferential surface 22 side of the stent body 2, multiple sub-drainage routes for draining body fluids such as bile can be secured, which is expected to extend the placement period. (e) By making the groove 23 spiral, the volume of the sub-drainage route can be increased, which makes it possible to increase the amount of drainage per unit time, and is expected to further extend the retention period. (f) When the tube stent 1 itself is bent or deformed, the protrusions 24 are distorted more than the grooves 23. This makes it easier to maintain the gap between the grooves 23 and the lumen even in the event of infiltration by tumors, etc., and makes it easier to maintain the amount of drainage per unit time. (g) By providing a sub-discharge route between the protrusions 24, the groove 23 can be used to place the tube stent 1 without contacting the lumen or the stent delivery catheter, making the tube stent 1 less susceptible to damage when placed or replaced, and providing a durable tube stent 1. (h) A plurality of tube stents 1 with different helical directions may be placed simultaneously. To make this possible, a plurality of tube stents 1 with different helical directions may be provided as a set, or a plurality of tube stents 1 with different helical directions may be provided as a set together with a medical device such as a stent delivery catheter. Also, a plurality of tube stents 1 with the same helical direction may be provided as a set, or a plurality or one tube stent 1 with the same helical direction may be provided as a set together with a medical device such as a stent delivery catheter.

[0034] [Second embodiment] Fig. 6 is a cross-sectional view of a tube stent according to a second embodiment of the present invention, corresponding to Fig. 2. In this embodiment, a reinforcing layer is added to the first embodiment. Hereinafter, this embodiment will be described, focusing on the differences from the first embodiment.

[0035] The stent body 2 of this embodiment is formed in a tubular shape as a whole, and includes an inner layer 2A having an inner circumferential surface 21, an outer layer 2B provided on the outside of the inner layer 2A and having an outer circumferential surface 22, and a reinforcing layer 3 formed on the outside of the inner layer 2A over the entire length. As in the first embodiment, the outer layer 2B has a plurality of grooves 23 formed on the outside of the outer circumferential surface 22, thereby forming a plurality of (for example, four) protrusions 24 between the grooves 23. As in the first embodiment, the plurality of grooves 23 and the protrusions 24 may be formed parallel to the axial direction of the lumen 20, or may be formed in a spiral shape.

[0036] The reinforcing layer 3 is configured to include, for example, a coil body formed by spirally winding a linear member, or a braided body formed by braiding a linear member. The reinforcing layer 3 may be configured by combining a coil body and a braided body in a layered manner. As the linear member, for example, a wire made of a metal (e.g., stainless steel, tungsten steel, titanium nickel alloy (Ti-Ni), etc.) or a wire made of a non-metal (e.g., nylon monofilament, polyethylene terephthalate (PET) monofilament, polyester monofilament, polyarylate fiber, etc.) can be used.

[0037] The inner layer 2A and the outer layer 2B may be formed from the same resin material or different resin materials. Examples of materials that can be used to form the inner layer 2A and the outer layer 2B include polyamide, polyurethane, polyethylene, silicone rubber, and fluororesin.

[0038] The diameter d of the lumen 20, the thickness t of the groove 23, and the depth h of the groove 23 may be the same as those in the first embodiment. In this case, the inner diameter of the outer layer 2B may be, for example, 0.90 mm or more and 2.00 mm or less. The thickness of the groove 23 (the thickness of the outer layer 2B) may be, for example, 0.05 mm or more and 0.25 mm or less. In addition, the stent body 2 in the first embodiment may be used as the outer layer 2B, and the inner layer 2A and the reinforcing layer 3 may be added thereto.

[0039] (Advantages of the second embodiment) According to the tube stent 1 of the second embodiment, the same effects as those of the first embodiment are achieved, and the kink resistance is improved.

[0040] [Third embodiment] FIG. 7A shows an Amsterdam-type tube stent according to a third embodiment of the present invention, where (a) is a left side view seen from the distal end, and (b) is a longitudinal cross-sectional view of the main part. FIG. 7B shows a Tanenbaum-type tube stent according to a third embodiment of the present invention, where (a) is a left side view seen from the distal end, and (b) is a front view of the main part. In this embodiment, one flap 26 is provided on each of the distal and proximal ends in the first embodiment shown in FIG. 1(a). In the case shown in FIG. 7A, the flap 26 is formed by cutting and raising the protruding part 24. 24d in FIG. 7A(b) is a recess after the flap 26 is cut and raised. Two, three, or four flaps 26 may be provided on each of the distal and proximal ends. Also, the flap 26 may be provided only on one of the distal and proximal ends.

[0041] According to the third embodiment, when the tube stent 1 is placed in a lumen of the body, the flap 26 can prevent the tube stent 1 from falling off from the lumen. In the case shown in Fig. 7A, the protrusion 24 is thicker than other parts, so the flap 26 can be easily formed by cutting and raising the protrusion 24. Note that the flap 26 may be formed by attaching a flap mounting member 27 having the flap 26 to the protrusion 24 at the end of the stent body 2 and fixing it by adhesion or the like, as shown in Fig. 7B. EXAMPLES

[0042] Table 1 shows the structures of Examples 1 to 7 and a comparative example. Examples 1a, 2a, 3a, 4a, and 5a correspond to the first embodiment shown in FIG. 1(a). Examples 1b, 2b, 3b, 4b, and 7b correspond to the first embodiment shown in FIG. 1(d). Examples 5a, 5b, and 6b correspond to the second embodiment.

[0043] The outer diameter D1 of Examples 1 to 7 indicates the diameter of a circle (circumscribed circle) 22a circumscribing the four protrusions 24. The outer diameter D2 of Examples 1 to 7 indicates the diameter of a circle (inscribed circle) 22b inscribing the four grooves 23. The diameter d of the inner cavity 20 of Examples 1 to 4 and Example 7b is equal to the inner diameter of the inner peripheral surface 21. The diameter d of Examples 5 and 6 indicates the inner diameter of the inner layer 2A. The comparative example has a tubular shape with inner and outer peripheral surfaces without grooves and protrusions, and the outer diameter D1 of the comparative example is the diameter of the outer peripheral surface.

[0044] The reinforcing layer 3 was a braided body made of PET monofilament. In Table 1, structures having the reinforcing layer 3 are indicated by "◯", and structures not having the reinforcing layer 3 are indicated by "X". Also in Table 1, the cases having the helical structure of the groove 23 are indicated by the helical pitch, and the cases not having the helical structure of the groove 23 are indicated by "X".

[0045] The greater the depth h (=h / d) of the groove 23 relative to the diameter d of the lumen 20, the greater the depth h of the groove 23 relative to the diameter d, indicating that when the tube stent 1 is placed in a curved lumen, at least one sub-exhaust route is secured without being collapsed.

[0046] [Table 1]

[0047] (Evaluation of drainage capacity) 8 is a schematic diagram of an experimental model for evaluating drainage capacity. A simulated lumen 300 simulating a bile duct was arranged vertically, and a stent to be tested was placed inside the simulated lumen 300 so that it was exposed about 15 mm from the lower end of the simulated lumen 300. Simulated bile 310 simulating bile was then poured from above the simulated lumen 300. Although bile is a non-Newtonian fluid, a yellow-colored glycerin aqueous solution (50%), which is a Newtonian fluid, was used as the simulated bile 310.

[0048] Table 2 shows the experimental results of the drainage capacity when the lumen 20 is open, and Table 3 shows the experimental results of the drainage capacity when the lumen 20 is closed.

[0049] Fig. 9 is a photograph showing the results of an experiment using the experimental model shown in Fig. 8. Specifically, Fig. 9 is a photograph showing the simulated bile 310 adhering to the outer peripheral surface of the tube stent after the simulated bile 310 was poured from above into the experimental model shown in Fig. 8. Fig. 9(a) shows the tube stent of Example 6b, Fig. 9(b) shows the tube stent of Example 7b, and Fig. 9(c) shows the tube stent of the comparative example.

[0050] As shown in Fig. 9, simulated bile 310 was not attached to the outer peripheral surface of the tube stent of the comparative example, and simulated bile 310 was attached to the outer peripheral surface 22 of the tube stent 1 of Example 6b and Example 7b. In other words, it is understood that the simulated bile 310 does not flow outside the outer peripheral surface of the stent of the comparative example, and a sub-exhaust route does not exist. On the other hand, the tube stent 1 of Example 6b and Example 7b has simulated bile 310 attached to the outer peripheral surface 22, and it is understood that a sub-exhaust route is functioning.

[0051] Fig. 10 is a photograph showing the results of an experiment conducted using the experimental model shown in Fig. 8. Specifically, Fig. 10 is a photograph showing simulated bile 310 adhering to the outer circumferential surface of the tube stent after the simulated bile 310 was poured from above in a state in which the upper end proximal portion of the lumen of the tube stent was blocked in the experimental model shown in Fig. 8.

[0052] As shown in Fig. 10, the simulated bile 310 was not attached to the outer peripheral surface of the tube stent of the comparative example, and the simulated bile 310 was attached to the outer peripheral surface 22 of the tube stents 1 of Examples 6b and 7b. In other words, it is understood that the simulated bile 310 does not flow outside the outer peripheral surface of the tube stent of the comparative example, and a sub-exhaust route does not exist. On the other hand, the simulated bile 310 is attached to the outer peripheral surface 22 of the tube stents 1 of Examples 6b and 7b, and it is understood that the sub-exhaust route is functioning.

[0053] The experimental results shown in Figure 9 are shown in Table 2, and the experimental results shown in Figure 10 are shown in Table 3. In Tables 2 and 3, the "lumen" of the drainage route indicates the main drainage route, and the "external flow path" indicates a secondary drainage route. "X" indicates a case where it did not exist as a drainage route, "△" indicates a case where it did not function well as a drainage route, and "○" indicates a case where it functioned sufficiently as a drainage route.

[0054] [Table 2]

[0055] [Table 3]

[0056] As can be seen from Tables 2 and 3, when the lumen of the tube stent is patent, all of the Examples and Comparative Examples function as a drainage route for the lumen. As for the drainage route for the external flow path, the Comparative Example does not function at all, and Example 1a, in which the groove 23 is not formed in a spiral shape, does not function sufficiently, but the other Examples 1b, 2a, 2b, 3a, 3b, 4a, 4b, 5a, and 5b function sufficiently.

[0057] 11(a), (b), and (c) are photographs showing a cross section of the tube stent of Example 1b placed in a narrowed simulated lumen 300. FIG. 11(a) shows a case where the simulated lumen 300 is compressed from the 12 o'clock direction, and the projection 24' at the 12 o'clock direction and the grooves 23 on both sides of the projection 24 are indistinguishable due to the infiltration of a tumor or the like from the 12 o'clock direction. In this case, the space between the grooves 23 on both sides of the projection 24 at the 6 o'clock direction and the simulated lumen 300 is not collapsed, and the space is secured as the external flow path 25. FIG. 11(b) shows a case where the simulated lumen 300 is compressed from the 6 o'clock direction and the 9 o'clock direction, and the projection 24' at the 6 o'clock direction and the grooves 23 between them are indistinguishable due to the infiltration of a tumor or the like from the 6 o'clock direction and the 9 o'clock direction, and the lumen 20 is almost blocked. In this case, the space between the groove 23 on the right side of the protrusion 24 in the 12 o'clock direction and the simulated lumen 300 is not collapsed, and thus the space is secured as the external flow path 25. Fig. 11(c) shows a case where the simulated lumen 300 is compressed from the 6 o'clock direction, and thus the protrusion 24' in the 6 o'clock direction and the grooves 23 on both sides thereof become indistinguishable due to infiltration of a tumor or the like from the 6 o'clock direction and bending of the tube stent 1. In this case, the space between the groove 23 on the right side of the protrusion 24 in the 10 o'clock direction and the simulated lumen 300 is not collapsed, and thus the space is secured as the external flow path 25.

[0058] (kink resistance) FIG. 12 is a photograph showing an experimental example for evaluating kink resistance with or without a reinforcing layer. When a tube stent is placed in the intrahepatic bile duct (posterior region), a curve of 180° with a radius of 20 mm is assumed as shown in FIG. 12. In this case, Example 1b, which does not have a reinforcing layer, is thinner than the comparative example (a commercially available resin stent), and therefore has poor kink resistance, with kinking (points marked with a circle). On the other hand, Example 5b, which has a reinforcing layer 3, did not have kinking (points marked with a circle). That is, by adding the reinforcing layer 3 to the inner circumferential surface 21 side of the stent body 2, the rigidity against kinking is improved, and the rigidity against bending is the same as that of existing resin stents, so that the main drainage route and multiple sub-drainage routes can be secured even against strong bending.

[0059] (Variation 1) In the first and second embodiments, the groove 23 is formed on the outer circumferential surface 22 side, but it may also be formed on the inner circumferential surface 21. This provides the effect of maintaining the inner cavity of the main discharge route.

[0060] (Variation 2) The shape of the tube stent 1 may be a pigtail type at one end or a pigtail type at both ends. The shape of the tube stent 1 may be an S-shape curved in an S-shape, or a J-shape curved at the tip side. In the first to third embodiments, the tube stent 1 may have a side hole.

[0061] (Variations 3 and 4) 13(a) and (b) are perspective views of the main part showing groove modifications 3 and 4, respectively. In the first to third embodiments, the groove 23 is formed by partially thinning the wall thickness of the stent body 2, but in modification 3, as shown in FIG. 13(a), a sub-discharge route is formed by weaving metal or resin linear members 4a and 4b. In modification 4, as shown in FIG. 13(b), a metal or resin linear member 4c is wound in a coil shape around the outer circumferential surface 22 of the stent body 2. Modifications 3 and 4 also make it possible to form an external flow path outside the outer circumferential surface 22.

[0062] Although the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above embodiment, and various modifications and implementations are possible. [Explanation of symbols]

[0063] 1...tube stent, 2...stent body, 2A...inner layer, 2B...outer layer, 2a...tip surface, 2b...base end surface, 3...reinforcing layer, 4a, 4b, 4c...linear member, 20...inner cavity, 21...inner peripheral surface, 22...outer peripheral surface, 22a...circumscribed circle, 22b...inscribed circle, 23...groove, 24, 24'...projection, 24a to 24c...corner, 24d...recess, 25...external flow path, 26...flap , 27...flap attachment member, 100...endoscope insertion portion, 101...tip portion, 101a...opening, 110...guide wire, 200...duodenum, 201...duodenal papilla, 202...bile duct, 202a...stenosis portion, 300...simulated lumen, 310...simulated bile, D1, D2...outer diameter, d...inner diameter, h...groove depth, p...helical pitch, t...groove thickness, X...longitudinal direction

Claims

1. A tubular stent to be placed in a lumen of a body, comprising: The stent body is made of resin and has an inner lumen defined by an inner circumferential surface along a longitudinal direction as a main discharge route, the stent body has a plurality of external flow paths formed over its entire length as a plurality of sub-exhaust routes so that bodily fluids from the body can flow along the longitudinal direction outside the outer circumferential surface of the stent body when the tube stent is placed in the lumen; The plurality of external flow paths are a plurality of grooves formed by partially thinning the wall thickness of the stent body, a volume of the plurality of sub discharge routes is substantially equal to a volume of the main discharge route; The stent body includes a reinforcing layer over the entire length thereof, the minimum thickness of the stent body at the groove is greater than or equal to 0.05 mm and less than or equal to 0.50 mm; When the tube stent is placed in the lumen and the cross-sectional area of ​​the main discharge route is reduced due to the tube stent being deformed in a radial direction or the main discharge route being blocked, at least one of the sub discharge routes can be secured. Tube stent.

2. the stent body includes an inner layer having the lumen on the inside thereof, and an outer layer provided outside the inner layer and having the plurality of grooves formed on an outer peripheral surface side thereof, The reinforcing layer is formed between the inner layer and the outer layer. The tube stent of claim 1.

3. The reinforcing layer is configured to include a coil body formed by spirally winding a linear member, or a braided body formed by braiding the linear member. The tube stent according to claim 2.

4. The plurality of grooves are two or more and five or less grooves formed at equal intervals in the circumferential direction. The tube stent of claim 1.

5. The plurality of grooves are formed parallel to the axial direction of the inner cavity.

5. The tube stent according to claim 4.

6. The plurality of grooves are formed in a spiral shape.

5. The tube stent according to claim 4.

7. A tube stent as described in claim 5 or 6, wherein when Vs is the volume over the entire length between a circle circumscribing a protrusion of the thick-walled portion formed by partially thinning the wall thickness of the stent body and one groove, and Vm is the volume over the entire length of the inner lumen, the following relationship is satisfied. NVs = kVm (where N is the number of grooves and k is 0.8 to 1.2)

8. The ratio of the depth of the groove to the inner diameter of the lumen is 0.025 or more and 0.55 or less.

7. A tube stent according to claim 5 or 6.

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