Stent

Abstract

To provide a stent capable of smoothly inserting a guide wire into the stent indwelled in the body.SOLUTION: The stent delivery system 50 includes the stent 1, an inner catheter 51, an outer catheter 52, and an operation unit 53, and the guide wire W passes through the stent delivery system 50. The stent 1 includes a stent tube wall portion 2 having an annular shape, a hollow stent insertion portion 3 surrounded by the stent tube wall portion 2 and penetrating the stent 1, and a flap portion 4 formed to protrude from a side surface of the stent tube wall portion 2. A notch part 11 having at least one or more notches 10 is provided on the rear end side of the stent 1. When the stent 1 is removed, the guide wire W can be easily inserted into the stent insertion portion 3 by inserting the distal end of the guide wire W into the notch 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a stent employed in a stent delivery system used for bile duct or pancreatic duct drainage, etc. [Background technology]

[0002] Conventionally, stents have been placed using a stent delivery system in order to expand and maintain a stricture formed in a lumens in the body, such as a blood vessel, digestive tract, bile duct, pancreatic duct, ureter, etc. Various stents have been proposed as such stents (for example, Patent Documents 1 and 2).

[0003] Patent Document 1 discloses that a coil is interposed within the stent in order to provide a medical stent whose lumen is less likely to collapse when bent. Patent Document 2 discloses that a pigtail type is adopted in order to enable efficient discharge of body fluids such as bile. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4981994 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-135590 Summary of the Invention [Problem to be solved by the invention]

[0005] A stent is delivered into the body by endoscopic surgery and placed at the target site, for example, to pass through a narrowed portion of the bile duct (see Figures 8 and 9 of Patent Document 1 and Figures 2 and 3 of Patent Document 2). After a predetermined period of time has passed, the stent is removed and replaced with, for example, a new stent.

[0006] However, conventional stents, which are placed inside the body protruding into the duodenum, have a simple cylindrical side surface and a flat rear end. For purposes such as replacement, a guidewire needs to be inserted into the placed stent. However, because the rear end is flat and the inner diameter of the stent insertion portion is at most 3 mm or less, it is difficult to smoothly insert the guidewire into the stent, making the surgery time-consuming.

[0007] In view of the above circumstances, an object of the present invention is to provide a stent that allows a guide wire to be smoothly inserted into the stent placed in the body.

[0008] These problems (issues) do not preclude the existence of other problems. Furthermore, each aspect of the present invention described below does not necessarily solve all of these problems (issues). Furthermore, other problems (issues) may be identified from the description of the specification, drawings, or claims. [Means for solving the problem]

[0009] The inventors of the present invention have continued to conduct extensive research into the above-mentioned problems and have discovered the following revolutionary stent.

[0010] A first aspect of the present invention for solving the above problem is a stent used in endoscopic surgery and through which a guide wire is inserted, the stent being made of resin and comprising a stent tubular wall portion, a hollow stent insertion portion surrounded by the stent tubular wall portion, and a notch portion provided on the rear end side of the stent tubular wall portion, wherein the notch portion has at least one or more notches formed by removing a portion of the stent tubular wall portion from the rear end surface of the stent tubular wall portion toward the center.

[0011] According to the first aspect, a stent placed in the body can be found under endoscopy, and the notch at the rear end of the stent that protrudes into a body lumen (e.g., into the duodenum) can be quickly found. Then, by guiding the tip of a guidewire toward the notch, the tip of the guidewire can be easily inserted into the notch. By protruding the tip of the guidewire from the notch, it can be easily inserted into the stent insertion portion. Further, by advancing the tip of the guidewire toward the distal end of the stent insertion portion, the guidewire can be inserted into the stent insertion portion. In other words, the notch can be quickly found, and the guidewire can be easily inserted into the stent insertion portion. As a result, the surgery can be performed accurately and the burden on the patient can be reduced. In particular, a stent suitable for surgery requiring a small outer diameter of the guidewire and a small inner diameter of the stent insertion portion can be provided.

[0012] A second aspect of the present invention is the stent according to the first aspect, characterized in that the shape formed by the inner walls of the notches is arc-shaped.

[0013] According to the second aspect, since the shape formed by the inner wall of the notch is arc-shaped, the tip of the guide wire can be easily inserted into the stent insertion portion without the guide wire getting caught.

[0014] A third aspect of the present invention is a stent according to the first or second aspect, characterized in that the opening diameter of the notch near the rear end surface of the stent tubular wall is formed to be the same as or larger than the outer diameter of the guide wire.

[0015] According to the third aspect, the tip of the guide wire can be inserted into the notch without resistance.

[0016] A fourth aspect of the present invention is the stent according to the first or second aspect, characterized in that the opening diameter of the notch near the rear end surface of the tubular wall of the stent is 1 to 6 times the outer diameter of the guidewire.

[0017] According to the fourth aspect, the guide wire can be more easily inserted into the notch.

[0018] A fifth aspect of the present invention is the stent according to the first or second aspect, characterized in that two to four notches are formed.

[0019] According to the fifth aspect, the tip of the guide wire can be more easily inserted into the notch.

[0020] A sixth aspect of the present invention is the stent according to the first aspect, characterized in that the outer diameter of the tubular wall of the stent increases toward the rear end surface.

[0021] According to the sixth aspect, the area of ​​the cutout portion is increased, so that the cutout can be formed larger. In addition, the cutout also widens toward the rear end of the stent, so that the tip of the guidewire can be easily guided into the cutout.

[0022] A seventh aspect of the present invention is a guidewire insertion method for inserting a guidewire into a stent insertion portion of a stent described in any one of the first to fifth aspects, comprising: a first insertion step of inserting the tip of the guidewire into a notch in the stent; a second insertion step of pushing the guidewire further into the stent insertion portion and inserting the tip of the guidewire into the stent insertion portion; and an insertion step of further inserting the guidewire toward the tip side of the stent insertion portion and inserting the guidewire into the stent insertion portion.

[0023] According to the seventh aspect, the tip of the guidewire is first inserted into the notch in the first insertion step, and while maintaining this state, the guidewire is pushed out in the second insertion step, thereby ensuring that the tip of the guidewire is inserted into the stent insertion portion, and the guidewire can be easily inserted into the stent insertion portion by changing the direction of travel of the guidewire in the insertion step and advancing it toward the stent tip side within the stent insertion portion. These steps allow for easy stent removal without relying on an experienced doctor. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic side view showing an example of a stent delivery system according to the present invention. [Figure 2] 2 shows the stent of FIG. 1, in which (a) is a side view, (b) is a schematic cross-sectional view taken along the line AA in (a), and (c) is a schematic back view of (a). [Figure 3] 2A to 2C show the rear end side of the stent in FIG. 1, with (a) being a schematic perspective view of Example 1, (b) being a schematic perspective view of Example 2, and (c) being a schematic perspective view of Example 3. FIG. [Figure 4] 2A and 2B are schematic diagrams showing the relationship between the stent and the guide wire in FIG. 1, in which (a) the guide wire is in an approaching state and (b) the guide wire is in an inserted state. [Figure 5] 1A and 1B are schematic cross-sectional views showing an example of connection between a stent and an outer catheter according to the present invention, in which (a) shows the state of engagement and (b) shows the state of engagement with an inner catheter inserted. [Figure 6] 1A and 1B are schematic diagrams showing an example of a method of using the bile duct drainage system of the present invention, in which (a) the stent is moved to the target site, and (b) the stent is placed. [Figure 7] Continuing from Figure 6, (a) the state of contact between the guidewire and the stent, and (b) the state of insertion of the guidewire into the stent. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of a stent according to the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the following embodiment.

[0026] (Embodiment 1) Fig. 1 is a schematic side view showing an example of a stent delivery system according to the present invention. Fig. 2 shows the stent of Fig. 1, where (a) is a schematic side view, (b) is a schematic cross-sectional view taken along line AA of (a), and (c) is a schematic rear view of (a). Fig. 3 shows the rear end side of the stent of Fig. 1, where (a) is a schematic perspective view of Example 1, (b) is a schematic perspective view of Example 2, and (c) is a schematic perspective view of Example 3. The stent and stent delivery system of the present invention will be described in detail with reference to Figs. 1 to 5.

[0027] The stent 1 of the present invention is one of the components of the stent delivery system 50, and is a medical device that is carried into the body along the guide wire W using the stent delivery system 50, used to expand a tubular part inside the body from the inside toward a target site (e.g., a narrowed area, etc.) inside the body, and is then left in the target site.

[0028] As shown in Fig. 1, the stent delivery system 50 includes a stent 1, an inner catheter 51, an outer catheter 52, and an operation unit 53. The operation unit 53 supports the inner catheter 51 and the outer catheter 52 and also operates an endoscope, a guidewire W, and the like. The stent 1 is disposed on the distal end side of the outer catheter 52. Here, the stent 1 may be of a straight type, an inside type, a pigtail type, or the like, and is not particularly limited in type, but the straight type will be described in this embodiment. In Fig. 1, the inner catheter 51 is indicated by a dashed line.

[0029] In the following, for ease of understanding of the configuration, the operation section 53 side will be described as the rear end side, and the opposite side will be described as the front end side.

[0030] Although stents 1 are also used in blood vessels, urinary tracts, etc., the stent 1 of this embodiment will be described mainly as being used for endoscopic biliary drainage (ERBD). Endoscopic biliary drainage is a treatment in which an endoscope is inserted through the mouth to reduce pressure in the bile duct where cholestasis has occurred due to acute cholangitis, stones, tumors, etc.

[0031] 2, the stent 1 comprises a ring-shaped stent tubular wall portion 2, a hollow stent insertion portion 3 that is surrounded by the stent tubular wall portion 2 and passes through the stent 1, and a flap portion 4 that is formed and protrudes from the side of the stent tubular wall portion 2. An inner catheter 51 is inserted into the stent insertion portion 3, and a guide wire W passes through the hollow inner catheter insertion portion that passes through the inner catheter 51.

[0032] The rear end of the stent 1 is provided with a notch 11 having at least one notch 10. The notch 10 is formed by cutting away a portion of the stent tubular wall 2 from the rear end surface 2a of the stent tubular wall 2 toward the center of the stent 1. That is, the notch 10 is an open opening hole having an inner wall 2b. The number of notches 10 is not particularly limited as long as it is one or more, but two to four notches are preferred. With one notch 10, it may be difficult to find the notch 10 with an endoscope depending on the positioning of the stent, and with more than four notches, the notches become too small, making it difficult to insert a guidewire.

[0033] When removing the stent 1 placed in the body and, for example, replacing it with a new stent, the guide wire W is used. The notch 10 acts as a guide, allowing the tip of the guide wire W to be smoothly inserted into the stent insertion portion 3.

[0034] As shown in FIG. 3, the shape formed by the inner wall 2b of the notch 10 is not particularly limited as long as it is concave, but may be selected from a rectangular shape (FIG. 3(a)) shown in Example 1, an arc shape (FIG. 3(b)) shown in Example 2, a trapezoidal shape (FIG. 3(c)) shown in Example 3, a U-shape, a triangular shape, and the like. Also, as shown in FIG. 3(b), the vicinity of the rear end surface 2a may be pillar-shaped, and the inner surface of the notch 10 may be arc-shaped. The inner wall 2b is also the location that comes into contact with the tip of the guidewire W, and a shape that allows easy insertion or contact of the guidewire W is preferred. Furthermore, since the outer periphery of the guidewire W is circular, the notch 10 is preferably arc-shaped for ease of fabrication.

[0035] In Examples 1 to 3, the outer diameter L2 near the rear end is larger than the outer diameter L1 near the center of the stent 1 (L2>L1). That is, the notch 11 of the stent 1 is tapered toward the rear end surface 2a of the stent tubular wall portion 2. By increasing the outer diameter on the rear end side, the notch 10 can be made larger, which makes it easier to insert the guidewire W.

[0036] As shown in FIG. 4 , the notch 10 is a guide that facilitates insertion of the tip of the guidewire W into the stent insertion portion 3. The guidewire W has a diameter (outer diameter) D1, and the opening diameter D2 near the tip surface 12 of the notch 10 of the stent 1 is the same as or wider than the diameter D1 (D2≧D1). The tip of the guidewire W can be easily inserted into the stent insertion portion 3 by inserting it into the notch 10 or inserting it into the notch 10 while making contact (abutting) with the inner wall 2b, and then bending the tip of the guidewire W. Here, the opening diameter D2 of the notch 10 is preferably 1 to 6 times, more preferably 2 to 5 times, and particularly preferably 2 to 3 times the outer diameter D1 of the guidewire W. If the opening diameter D2 of the notch 10 is smaller than the outer diameter D1 of the guidewire W, the guidewire W cannot be inserted into the notch 10. On the other hand, if the opening diameter D2 of the notch 10 exceeds six times the outer diameter D1 of the guidewire W, it becomes difficult to form two or more notches 10.

[0037] If the operation of inserting the guidewire W into the stent insertion portion 3 is considered as a process, this operation includes a guidewire insertion process of inserting the guidewire W into the stent insertion portion 3, a first insertion process of inserting the tip of the guidewire W into the notch 10 of the stent 1, a second insertion process of pushing the guidewire W further into the stent insertion portion 3 while it is inserted and inserting the tip of the guidewire W into the stent insertion portion 3, and an insertion process of inserting the guidewire W further toward the tip side of the stent insertion portion 3 and inserting the guidewire W into the stent insertion portion 3.

[0038] The stent 1 is molded from a resin. The resin is not particularly limited, but may be selected from, for example, polyamide elastomer resin, polyethylene elastomer resin, polyethylene resin, polystyrene elastomer, or polyurethane elastomer resin. Resin is easily deformable, making it easy to insert the guidewire W into the notch 10. Furthermore, since it can be deformed after insertion, it is easy to insert the guidewire W into the stent insertion portion 3. Note that, when a metal stent is used, there is a problem in that the guidewire may get caught on the stent, but this problem does not occur in the present invention.

[0039] Here, the stent 1 placed in the body needs to be removed when abnormalities in position, length, or contamination are found, when it needs to be replaced after a certain period of time, or when the patient's condition improves. Removal is generally performed using a guidewire W. For removal, the guidewire W generally approaches the stent tube wall portion 2 from the side. In particular, in the case of biliary drainage, the direction in which the stent 1 protrudes into the duodenum is perpendicular to the direction in which the duodenum is formed. Furthermore, the inner diameter of the stent insertion portion 3 is at most 1 mm or less. When using conventional stents, it is difficult to insert the tip of the guidewire W into the stent insertion portion 3 under endoscopic guidance, which makes the surgery more time-consuming and increases the burden on the patient.

[0040] On the other hand, the stent 1 of this embodiment has a notch 10 formed in the cutout portion 11, and as will be described later, this notch 10 can be used to easily insert the tip of the guidewire W into the stent insertion portion 3 from the side of the stent tubular wall portion 2, thereby reducing the burden on the surgery and also reducing the burden of relying on an experienced doctor.

[0041] The relationship between the stent 1 and the outer catheter 52 while the stent delivery system 50 is moving within the body will be described with reference to FIG. 5. The rear end of the stent 1 and the front end of the outer catheter 52 may or may not be connected. To prevent the stent 1 from shifting position during movement within the body, a mating connection is used, as disclosed in Japanese Patent No. 6514814. A first mating portion 60 is provided on the stent 1, and a second mating portion 61 is provided on the outer catheter 52, which are temporarily mated (see FIG. 5(a)). The inner catheter 51 is then inserted to complete the mating (see FIG. 5(b)). The stent 1 is then positioned at the target site, and the inner catheter 51 is removed from the first mating portion 60, releasing the mating, allowing the stent 1 to be placed at the target site. This mating connection is described in Japanese Patent No. 6514814, and will not be described in detail here.

[0042] Alternatively, the connection may be made with thread as disclosed in Japanese Patent No. 4913251. There are no particular limitations on the connection structure, and the stent 1 can also be held in place by friction between the inner surface of the stent tubular wall portion 2 and the outer surface of the inner catheter tubular wall portion, and no connection is necessary.

[0043] 6 and 7, the use of the stent 1 of this embodiment will be described using biliary drainage as an example.

[0044] The stent delivery system 50 can be used in conjunction with an endoscope to deliver the inner catheter 51, the outer catheter 52, and the stent 1 to a target site (a stricture) in the body. A guidewire W is first introduced into, for example, a bile duct through a channel in the endoscope, and the tip of the guidewire W is inserted to a position where it passes the stricture. Next, the stent delivery system 50 is attached to the guidewire W from its proximal side, and the stent 1 is inserted to a position where it passes the stricture in the bile duct, in accordance with the position of the guidewire W in the body.

[0045] That is, the stent 1 is inserted from the duodenum 100 into the papilla 102 of the bile duct 101 and advanced to the stricture 103 where the bile duct is narrowed (see FIG. 6(a)). Next, the guidewire W, outer catheter 52, and inner catheter 51 are removed from the body, and only the stent 1 is left in place at the target site, allowing the stagnant bile to be excreted (see FIG. 6(b)).

[0046] When it is time to remove the stent 1, the guidewire W is moved closer to the rear end of the stent 1 using an endoscope. At this time, the protruding direction of the rear end of the stent 1 into the duodenum 100 is approximately perpendicular to the extending direction of the duodenum 100. This is because the bile duct 101 is approximately perpendicular to the extending direction of the duodenum 100. Therefore, it is difficult to insert the guidewire W into the stent insertion portion 3. However, in this embodiment, a notch 11 is provided at the rear end of the stent 1, and the tip of the guidewire W can be inserted using the notch 10 formed in the notch 11 (see FIG. 7(a)). This allows the tip of the guidewire W to be easily inserted into the stent insertion portion 3, and at the same time, the tip of the guidewire W can be further inserted toward the tip side of the stent insertion portion 3 (see FIG. 7(b)). This facilitates placement of the tip of the guidewire W beyond the stricture 103 (the upstream side of the bile duct (toward the liver)). Then, the stent 1 can be removed using forceps or the like, leaving the guide wire W in place.

[0047] (Other embodiments) The present invention is not limited to the above-described embodiments and can be modified, improved, etc. as appropriate. Furthermore, the material, shape, dimensions, numerical values, configuration, number, placement location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention. For example, in embodiment 1, the stent is provided with a flap portion, but the flap portion need not be provided. [Explanation of symbols]

[0048] 1 stent 2. Stent tube wall 2a Rear end surface 2b Inner wall 3 Stent insertion section 4 Flap section 10 Notch 11 Notch 12 Tip surface 50 Stent Delivery System 51 Inner catheter 52 Outer catheter 53 Operation section 60 First fitting part 61 Second fitting part 100 duodenum 101 Bile duct 102 Nipple 103 Stenosis L1: Outer diameter of the stent near the center L2 Outer diameter of the stent near the rear end D1 Guidewire diameter D2 Opening diameter D2 near the tip of the notch in the stent W Guidewire

Claims

1. A stent used in endoscopic surgery through which a guide wire is inserted, It is made of resin, a stent tube wall; a hollow stent insertion portion surrounded by the stent tube wall portion; a notch provided on the rear end side of the stent tube wall portion, The cutout portion has at least one cutout formed by cutting out a part of the stent tube wall portion from the rear end surface of the stent tube wall portion toward the center. A stent characterized by:

2. The shape formed by the inner wall of the notch is an arc shape. The stent of claim 1.

3. The opening diameter of the notch in the vicinity of the rear end surface of the stent tube wall portion is formed to be equal to or larger than the outer diameter of the guide wire.

3. The stent of claim 1 or 2.

4. the opening diameter of the notch in the vicinity of the rear end surface of the stent tube wall portion is 1 to 6 times the outer diameter of the guide wire.

3. The stent of claim 1 or 2.

5. Two to four of the notches are formed.

3. The stent according to claim 1 or 2.

6. The outer diameter of the stent tube wall portion increases toward the rear end surface. The stent of claim 1.

7. A guidewire insertion method for inserting the guidewire into the stent insertion portion of the stent according to claim 1, comprising: a first insertion step of inserting a tip of the guide wire into the notch of the stent; a second insertion step of further pushing the guide wire into the stent insertion portion and inserting the tip of the guide wire into the stent insertion portion; and an insertion step of further inserting the guide wire toward the distal end side of the stent insertion portion and inserting the guide wire into the stent insertion portion. A guidewire insertion method for inserting a guidewire into a stent insertion portion.

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