Medical device and endoscopic treatment instrument

Abstract

This medical device is provided with an endoscope and an endoscopic treatment instrument. An insertion portion of the endoscope has a lumen for the treatment instrument and a curved part. The endoscopic treatment instrument includes: a tube having a lumen for a knife wire; a knife wire housed in the lumen for the knife wire; and a support member for rotatably supporting a proximal end part of the knife wire. The knife wire includes: a first wire part including an exposed part that can be exposed on the outer peripheral side of the tube; and a second wire part positioned on the base end side of the first wire part and having a rigidity higher than that of the exposed part of the first wire part. In a specific state in which the endoscopic treatment instrument is inserted into the lumen for the treatment instrument and a portion between the position of the distal end of the exposed portion of the knife wire exposed from the tube and a point at a predetermined distance toward the proximal end protrudes from an opening of the insertion portion, the distal end of the second wire part is positioned closer to the distal end than the proximal end of the curved part.

Description

Medical devices and endoscopic treatment tools

[0001] The technology disclosed in this specification relates to a medical device and an endoscopic treatment tool.

[0002] Endoscopic sphincterotomy (EST) is known as a treatment for common bile duct stones. Endoscopic sphincterotomy uses a medical device including an endoscope and an incision instrument serving as an endoscopic treatment tool. The insertion section of the endoscope is formed with a treatment tool lumen that opens at the distal end of the insertion section. An incision instrument is inserted into the treatment tool lumen of the endoscope, and biological tissue is incised with the distal end of the incision instrument protruding from the distal opening of the treatment tool lumen.

[0003] An incision instrument used in endoscopic papillotomy includes a tube with a wire lumen, a knife wire (cutting wire) housed in the wire lumen, and a support member that rotatably supports the base end of the knife wire (see, for example, Patent Document 1). A portion of the knife wire (hereinafter referred to as the "exposed portion") is exposed on the outer periphery of the tube at all times or when the tube is in a predetermined position. By applying a high-frequency current to the knife wire from a high-frequency power source, biological tissue can be incised by the exposed portion of the knife wire.

[0004] The operator rotates the support member of the incision instrument to incise a predetermined shape in a predetermined area of ​​biological tissue in the papilla. This generates a rotational torque at the base end of the knife wire supported by the support member, and this rotational torque is transmitted to the tube via the knife wire. As a result, the tube rotates around its central axis, and the orientation of the exposed part of the knife wire changes to the desired orientation.

[0005] Patent No. 4896351

[0006] The insertion section of an endoscope has a bending portion that can be bent by a bending operation, located proximal to the distal end of the distal end where the opening of the treatment instrument lumen is formed. When the bending portion of the endoscope is bent, the knife wire of the incision instrument inserted into the treatment instrument lumen of the endoscope is also bent. In this state, the rotational torque generated by rotating the support member that supports the proximal end of the knife wire is not effectively transmitted to the distal end of the knife wire at the bending portion, which may prevent the exposed portion of the knife wire from smoothly changing to the desired orientation. While it is possible to reduce the diameter of a portion of the tube to reduce the torsional rigidity of that portion, this would result in the inner and outer diameters of that portion becoming smaller, making it impossible to form a lumen of the required size. It is also possible to increase the outer diameter of the knife wire to improve rotational torque transmission, but increasing the outer diameter of the knife wire may reduce the incision ability of the knife wire.

[0007] As such, conventional cutting instruments have the problem that it is not possible to smoothly change the orientation of the exposed portion of the knife wire to the desired orientation by rotating the support member while maintaining the inner and outer diameters of the tube and the outer diameter of the knife wire.

[0008] Furthermore, these issues are not limited to endoscopic treatment instruments and medical devices used in endoscopic papillotomy, which cuts open the papilla, but are common to all endoscopic treatment instruments and medical devices that are inserted into various organs within the human body, such as the vascular system, lymphatic system, biliary system, urinary system, respiratory system, digestive system, secretory glands, and reproductive organs, to cut open biological tissue.

[0009] This specification discloses a technique that can solve the above-mentioned problems.

[0010] The technology disclosed in this specification can be realized, for example, in the following forms.

[0011] (1) A medical device disclosed herein includes an endoscope having an insertion section for insertion into a subject, and an endoscopic treatment tool. The insertion section of the endoscope includes a treatment tool lumen that opens at the distal end of the insertion section and through which the endoscopic treatment tool is inserted, and a bending section that is located proximal to the distal end and bends when bent. The endoscopic treatment tool includes a tube having a knife wire lumen, a knife wire housed in the knife wire lumen, and a support member that rotatably supports the proximal end of the knife wire. The knife wire includes a first wire section including an exposed section that is exposed on the outer periphery of the tube, and a second wire section that is located proximal to the first wire section and has higher rigidity than the exposed section of the first wire section. When the endoscopic treatment tool is inserted into the treatment tool lumen and a portion of the knife wire exposed from the tube protrudes from the opening of the insertion section by a predetermined distance proximal to the distal end, the tip of the second wire section is located distal to the proximal end of the bending section.

[0012] According to this medical device, in the specific state, the tip of the second wire portion of the knife wire, which has a higher rigidity than the first wire portion, is located distal to the proximal end of the bending portion of the endoscope. That is, in the specific state, a portion of the knife wire with a higher rigidity than the first wire portion is located in the bending portion of the endoscope. Therefore, even when the bending portion of the endoscope is bent and the knife wire is bent, the rotational torque generated by rotating the support member is effectively transmitted to the distal end of the portion of the knife wire located in the bending portion, allowing the orientation of the exposed portion of the knife wire to be smoothly changed to a desired orientation. Therefore, according to this medical device, the orientation of the exposed portion of the knife wire can be smoothly changed to a desired orientation by rotating the support member while maintaining the inner and outer diameters of the tube and the outer diameter of the knife wire.

[0013] (2) In the above medical device, the distal end of the second wire portion may be located distally of the longitudinal center of the bending portion in the specific state. With this configuration, a relatively rigid portion of the knife wire is located over more than half of the longitudinal length of the bending portion of the endoscope in the specific state. This allows the rotational torque generated by rotating the support member to be more effectively transmitted to the distal end, thereby enabling the orientation of the exposed portion of the knife wire to be more smoothly changed to a desired orientation.

[0014] (3) In the medical device, the first wire portion may be cylindrical, and the second wire portion may be tapered so that its diameter increases from the distal end to the proximal end. This configuration makes it possible to provide a second wire portion with relatively high rigidity while suppressing a rigidity gap in the knife wire.

[0015] (4) In the above medical device, the knife wire may include a tapered third wire portion located proximal to the second wire portion, having higher rigidity than the distal end of the second wire portion, and expanding in diameter from the distal end to the proximal end, wherein in the specific state, the distal end of the third wire portion is located proximal to the proximal end of the bending portion. With this configuration, a relatively large-diameter third wire portion is not disposed in the bending portion of the endoscope, thereby preventing a decrease in slidability of the endoscopic treatment tool in the treatment tool lumen of the endoscope.

[0016] (5) In the above medical device, the knife wire may include a cylindrical third wire portion located proximal to the second wire portion and exhibiting higher rigidity than the distal end of the second wire portion, wherein the distal end of the third wire portion is located proximal to the proximal end of the bending portion in the specific state. With this configuration, a relatively large-diameter third wire portion is not disposed in the bending portion of the endoscope, thereby preventing a decrease in the slidability of the endoscopic treatment tool in the treatment tool lumen of the endoscope.

[0017] (6) In the above medical device, the knife wire may include a cylindrical third wire portion located proximal to the second wire portion and having higher rigidity than the distal end of the second wire portion, and a tapered fourth wire portion located proximal to the third wire portion and having higher rigidity than the distal end of the third wire portion and expanding in diameter from the distal end to the proximal end, wherein in the specific state, the distal end of the third wire portion is located distal to the proximal end of the bending portion, and the distal end of the fourth wire portion is located proximal to the proximal end of the bending portion. With this configuration, a relatively large-diameter fourth wire portion is not disposed in the bending portion of the endoscope, thereby preventing a decrease in slidability of the endoscopic treatment tool in the treatment tool lumen of the endoscope.

[0018] (7) In the above medical device, the minimum diameter of the exposed portion of the knife wire may be 0.15 mm or more and 0.30 mm or less. With this configuration, it is possible to achieve both improved rotational torque transmission performance of the knife wire and improved cutting ability of the knife wire.

[0019] The technology disclosed in this specification can be realized in various forms, such as an incision instrument, an endoscopic treatment tool, a medical device or medical system including an incision instrument or an endoscopic treatment tool and an endoscope, a method of manufacturing these devices and systems, etc.

[0020] FIG. 3 is a diagram showing the external configuration of the medical device 300 according to the first embodiment; FIG. 4 is a diagram showing the external configuration of the medical device 300 according to the first embodiment; FIG. 5 is a diagram showing the external configuration of the incision instrument 100 according to the first embodiment; FIG. 6 is a diagram showing the cross-sectional configuration (XY cross-section) of the incision instrument 100 at the position IV-IV in FIG. 3; FIG. 7 is a diagram showing the longitudinal cross-sectional configuration (YZ cross-section) of the tip of the incision instrument 100; FIG. 8 is a diagram showing an example of a method of operating the incision instrument 100; FIG. 9 is a diagram showing an example of a method of operating the incision instrument 100; FIG. 10 is a diagram showing the detailed configuration of the knife wire 20 according to the first embodiment;

[0021] A. First Embodiment: (Configuration of Medical Device 300) Fig. 1 is an explanatory diagram showing the external configuration of a medical device 300 according to a first embodiment. The medical device 300 according to this embodiment is used, for example, in endoscopic sphincterotomy (EST) for treating choledocholithiasis. Note that the medical device 300 is not limited to endoscopic sphincterotomy, and may be inserted into various organs in the human body, such as the vascular system, lymphatic system, biliary system, urinary system, respiratory system, digestive system, secretory glands, and reproductive organs, to incise biological tissue.

[0022] In FIG. 1 , some components of the medical device 300 are omitted as appropriate. Also, FIG. 1 shows X, Y, and Z axes that are orthogonal to each other. The positive Z-axis side is the tip end (distal side) that is inserted into the body, and the negative Z-axis side is the base end (proximal side) that is operated by a surgeon such as a doctor. In FIG. 1 , the long portion of the medical device 300 is shown as being substantially linear and parallel to the Z-axis, but at least a portion of the medical device 300 is flexible enough to be bent. This also applies to the subsequent figures. In this specification, with regard to the medical device 300 and its components, the tip end is referred to as the "tip end," the tip and its vicinity are referred to as the "tip portion," the base end is referred to as the "base end," and the base end and its vicinity are referred to as the "base portion."

[0023] The medical device 300 includes an endoscope 200 and an incision instrument 100 as an endoscopic treatment tool.

[0024] (Configuration of endoscope 200) The endoscope 200 is a device that is inserted into a subject (for example, the inside of a patient's lumen) to observe the interior. The endoscope 200 has an insertion section 220 and a connecting section 210 connected to the proximal end of the insertion section 220. The endoscope 200 is formed with a treatment tool lumen 222 that extends from the insertion section 220 to the connecting section 210 and into which the incision tool 100 is inserted.

[0025] The insertion section 220 of the endoscope 200 is the portion that is inserted into the subject, and is configured to be flexible and elongated. The insertion section 220 has a distal end portion 230 and a bending portion 224. An opening 232 on the distal end side of the treatment tool lumen 222 is formed on the outer peripheral surface of the distal end portion 230. A camera 234 is also disposed on the outer peripheral surface of the distal end portion 230. An image signal generated by the camera 234 is transmitted via a signal line (not shown) to an image display device (not shown) connected to the proximal end of the endoscope 200, and an image is displayed on the image display device.

[0026] A control wire (not shown) is connected to the bending portion 224 of the insertion section 220 of the endoscope 200. When a bending control section (not shown) provided at the proximal end of the endoscope 200 is operated, tension is generated in the control wire, and the bending portion 224 is bent at a predetermined bending angle θ1. FIG. 2 shows the bending portion 224 of the endoscope 200 in a bent state. The length of the bending portion 224 along the longitudinal direction (Z-axis direction) is, for example, approximately 40 mm to 100 mm. Furthermore, the distance from the opening 232 along the longitudinal direction to the tip of the bending portion 224 is, for example, approximately 10 mm to 20 mm.

[0027] An insertion port 214 for an endoscopic treatment tool is formed in the connecting portion 210 of the endoscope 200. The insertion port 214 is an opening on the proximal end side of the treatment tool lumen 222.

[0028] (Configuration of incision instrument 100) Figure 3 is an explanatory diagram showing the external configuration of incision instrument 100 of the first embodiment, Figure 4 is an explanatory diagram showing the configuration of a transverse section (XY section) of incision instrument 100 at position IV-IV in Figure 3, and Figure 5 is an explanatory diagram showing the configuration of a longitudinal section (YZ section) of the tip of incision instrument 100. The incision instrument 100 is an instrument for incising biological tissue, and is used, for example, in endoscopic papillotomy for the treatment of choledocholithiasis as described above.

[0029] The incision instrument 100 includes a tube 10, a knife wire 20, a connector 30, and a handle portion 40. Fig. 3 shows the central axis Ax of the tube 10. In this embodiment, the central axes of the connector 30 and the handle portion 40 substantially coincide with the central axis Ax of the tube 10. However, these central axes may differ from the central axis Ax of the tube 10.

[0030] The tube 10 is an elongated member extending along a central axis Ax. As shown in Fig. 4, the outer shape of the cross section of the tube 10 is, for example, substantially circular or substantially elliptical. The outer diameter of the tube 10 may be constant over its entire length or may vary along the longitudinal direction.

[0031] The tube 10 is formed with a device lumen 16L, a knife wire lumen 17L, and a fluid supply lumen 18L. The device lumen 16L is a lumen through which a combined device such as a guidewire is housed (inserted), and extends longitudinally from the distal end of the tube 10 to a branching portion 19 provided at the proximal end of the tube 10. The knife wire lumen 17L is a lumen through which a knife wire 20 is housed (inserted), and extends longitudinally from the distal end to the proximal end of the tube 10. The fluid supply lumen 18L is a lumen through which a liquid such as a contrast agent or saline solution flows, and extends longitudinally from the distal end to the proximal end of the tube 10. The cross-sectional outer shape of each lumen is, for example, approximately circular or approximately elliptical. 4, in this embodiment, the diameter W16 of the device lumen 16L is larger than the diameter W17 of the knife wire lumen 17L, which is larger than the diameter W18 of the liquid supply lumen 18L. The relationship between the diameters of the lumens can be changed as desired.

[0032] The tube 10 preferably has antithrombogenicity, flexibility, and biocompatibility, and can be made of, for example, a resin material or a metal material. Examples of resin materials that can be used to form the tube 10 include polyamide resin, polyolefin resin, polyester resin, polyurethane resin, silicone resin, and fluororesin. Examples of metal materials that can be used to form the tube 10 include stainless steel such as SUS304, Ni-Ti alloys, and cobalt-chromium alloys.

[0033] The knife wire 20 is an elongated member used to incise biological tissue. The knife wire 20 is housed in a knife wire lumen 17L formed in the tube 10. The distal end of the knife wire 20 is fixed to the distal end of the tube 10. More specifically, as shown in FIG. 5 , a fixing member 80 is filled in the distal end of the knife wire lumen 17L, and the distal end 28 of the knife wire 20 is fixed to the fixing member 80 and thereby fixed to the distal end of the tube 10. The length of the portion of the knife wire 20 embedded in the fixing member 80 is, for example, approximately 1 mm. Furthermore, as shown in FIG. 3 , a proximal end 29 of the knife wire 20 extends from the proximal end of the knife wire lumen 17L through the inner cavity of the connector 30 to the position of the handle portion 40 and is supported by a wire support portion 45 (described later) of the handle portion 40.

[0034] A portion of the knife wire 20 (hereinafter referred to as the "exposed portion 20E") is exposed on the outer periphery of the tube 10 between the distal end and proximal end of the tube 10. More specifically, as shown in FIG. 5 , the tube 10 is formed with a distal hole 12 and a proximal hole 13 that communicate between the knife wire lumen 17L and the outside. The portion of the knife wire 20 proximal to the distal end 28 fixed to the fixing member 80 within the knife wire lumen 17L is exposed to the outside of the tube 10 via the distal hole 12, and the further proximal portion is housed again within the knife wire lumen 17L via the proximal hole 13. The exposed portion 20E of the knife wire 20 is the portion from the position where it passes through the distal hole 12 to the position where it passes through the proximal hole 13. The length of the exposed portion 20E of the knife wire 20 is, for example, approximately 20 mm to 30 mm. The minimum diameter of the exposed portion 20E of the knife wire 20 is, for example, 0.15 mm or more and 0.30 mm or less. The minimum diameter of the exposed portion 20E of the knife wire 20 may be, for example, 0.18 mm or more and 0.25 mm or less. In this embodiment, the distal side hole 12 and the proximal side hole 13 are formed on the outer peripheral surface of the tube 10.

[0035] A high-frequency current is applied to the knife wire 20 from a high-frequency power supply (not shown). The high-frequency power supply is connected to the wire support portion 45. When the high-frequency power supply is connected to the wire support portion 45, the wire support portion 45 can be made of a conductive material, such as a metal. This allows the exposed portion 20E of the knife wire 20 to incise biological tissue.

[0036] The knife wire 20 preferably has electrical conductivity, antithrombogenicity, and biocompatibility, and can be formed from a metal material such as a stainless steel alloy such as SUS302, SUS304, or SUS316, a Ni-Ti alloy, a nickel-chromium alloy, a cobalt alloy, gold, platinum, tungsten, or an alloy containing these elements.

[0037] As shown in Figure 3, the connector 30 is a tubular member connected to the base end of the tube 10. The connector 30 has a small diameter section 31, a tapered section 32, and a large diameter section 33. The small diameter section 31 is a section that forms the tip end of the connector 30 and has a substantially constant outer diameter. The large diameter section 33 is a section that forms the base end of the connector 30 and has a substantially constant outer diameter that is larger than the outer diameter of the small diameter section 31. The tapered section 32 is provided between the small diameter section 31 and the large diameter section 33, and is a section whose outer diameter gradually increases from the boundary with the small diameter section 31 to the boundary with the large diameter section 33.

[0038] A branch portion 39 extending in a direction intersecting the central axis Ax is formed in the small-diameter portion 31 of the connector 30. The inner cavity of the branch portion 39 communicates with the liquid supply lumen 18L formed in the tube 10. Therefore, a liquid such as a contrast medium or saline can be supplied to the liquid supply lumen 18L via the branch portion 39.

[0039] The handle portion 40 is disposed on the base end side of the connector 30. The handle portion 40 has a shaft portion 41 and a handle main body portion 42. The shaft portion 41 is a substantially cylindrical member and is connected to the base end of the connector 30. The inner cavity of the shaft portion 41 communicates with the inner cavity of the connector 30. A ring-shaped first finger receiving portion 43 is provided at the base end of the shaft portion 41.

[0040] The handle main body 42 is a substantially cylindrical member and is attached to the shaft 41 so as to be slidable along the central axis Ax. The handle main body 42 is provided with a wire support portion 45 that protrudes into the inner cavity of the shaft 41, and the base end 29 of the knife wire 20 is supported (fixed) by the wire support portion 45. In addition, a pair of ring-shaped second finger rests 44 are provided on the side surface of the handle main body 42. The handle main body 42 is an example of a support member.

[0041] The connector 30 and the handle portion 40 can be made of, for example, a resin material, such as polyurethane, polypropylene, hard polyvinyl chloride, polycarbonate resin, or acrylic resin.

[0042] (Method of Operating the Dissection Instrument 100) FIGS. 6 and 7 are explanatory diagrams showing an example of a method of operating the dissection instrument 100. As shown in FIG. 6 , the operator, for example, inserts the thumb through the first finger receiving portion 43 and the index finger and middle finger through the second finger receiving portion 44, and then rotates the handle main body 42 relative to the tube 10 (arrow AR2). This generates a rotational torque at the proximal end 29 of the knife wire 20, which is supported by the wire support portion 45 of the handle main body 42. This rotational torque is transmitted via the knife wire 20 to the distal end of the tube 10, which is fixed to the distal end of the knife wire 20. This causes the tube 10 to rotate around the central axis Ax, thereby changing the orientation of the exposed portion 20E of the knife wire 20. The dissection instrument 100 may also have a locking mechanism that fixes the rotation angle of the handle main body 42 (i.e., the orientation of the exposed portion 20E of the knife wire 20).

[0043] 7 , for example, when the operator inserts the thumb through the first finger rest 43 and the index and middle fingers through the second finger rest 44 and then pulls the index and middle fingers toward the proximal end (arrow AR1), the handle main body 42 moves toward the proximal end along the outer circumferential surface of the shaft 41. This pulls the proximal end 29 of the knife wire 20, which is supported by the wire support portion 45 of the handle main body 42, toward the proximal end, applying tension to the knife wire 20. This tension causes the distal end of the tube 10, which is fixed to the distal end of the knife wire 20, to bend in an arched shape. Returning the handle main body 42 to the distal end relieves the tension on the knife wire 20, and the distal end of the tube 10 returns to a substantially straight shape.

[0044] (Procedure Using Medical Instrument 300) Next, a procedure for incising the papilla using the medical instrument 300 in endoscopic papillotomy will be described. First, the operator inserts the endoscope 200 into the duodenum and delivers a guidewire (combined device) inserted into the endoscope 200 from the opening of the papilla to the common bile duct. Next, the operator delivers the incision instrument 100 along the guidewire to the opening of the papilla. Specifically, after inserting the proximal end of the guidewire into the distal opening of the device lumen 16L of the incision instrument 100, the operator inserts the incision instrument 100 into the treatment instrument lumen 222 from the insertion port 214 of the endoscope 200 and advances the incision instrument 100 toward the distal end (distal side) until the distal end of the incision instrument 100 protrudes from the opening 232 of the distal end portion 230 of the endoscope 200 and reaches the opening of the papilla. At this time, the operator positions the handle main body 42 toward the distal end (FIG. 3). This makes the tip of the tube 10 straight, and prevents the tip of the tube 10 from getting caught on the papilla or common bile duct when the incision instrument 100 is delivered.

[0045] Next, the operator rotates the handle body 42 of the handle portion 40 relative to the tube 10 (Figure 6, arrow AR2), thereby rotating the tip of the tube 10 and setting the orientation of the exposed portion 20E of the knife wire 20 to an appropriate orientation for incising the papilla.

[0046] The operator then applies tension to the knife wire 20 by sliding the handle main body 42 along the outer circumferential surface of the shaft 41 toward the proximal end (arrow AR1 in FIG. 7 ). This bends the distal end of the tube 10 into an arch shape, and the exposed portion 20E of the knife wire 20 is pressed against the incision site. In this state, the operator applies a high-frequency current to the knife wire 20 from the high-frequency power supply. This causes the exposed portion 20E of the knife wire 20 to incise a predetermined area of ​​the papilla into a predetermined shape.

[0047] As described above, the insertion section 220 of the endoscope 200 has a bending section 224. The operator bends the bending section 224, for example, to match the shape of a lumen in the body ( FIG. 2 ). When the bending section 224 of the endoscope 200 is bent, the tube 10 of the incision instrument 100 inserted into the treatment tool lumen 222 of the endoscope 200 is also bent. The rotation operation for changing the orientation of the exposed portion 20E of the knife wire 20 described above can be performed even when the tube 10 of the incision instrument 100 is bent in this manner.

[0048] (Detailed Configuration of Knife Wire 20) Fig. 8 is an explanatory diagram showing the detailed configuration of the knife wire 20 in the first embodiment. Fig. 8 shows the external configuration of the tip of the knife wire 20.

[0049] The knife wire 20 of this embodiment includes, in order from the distal end to the proximal end, a first wire portion 21, a second wire portion 22, a third wire portion 23, a fourth wire portion 24, and a fifth wire portion 25. The first wire portion 21 includes the exposed portion 20E. The length of the first wire portion 21 is, for example, approximately 60 mm to 80 mm, the length of the second wire portion 22 is, for example, approximately 10 mm to 30 mm, the length of the third wire portion 23 is, for example, approximately 25 mm to 45 mm, and the length of the fourth wire portion 24 is, for example, approximately 20 mm to 40 mm.

[0050] The first wire portion 21, the third wire portion 23, and the fifth wire portion 25 are cylindrical portions with a substantially constant outer diameter. The outer diameter of the first wire portion 21 is, for example, approximately 0.15 mm to 0.26 mm. The outer diameter of the third wire portion 23 is larger than the outer diameter of the first wire portion 21, for example, approximately 0.26 mm to 0.40 mm. The outer diameter of the fifth wire portion 25 is larger than the outer diameter of the third wire portion 23, for example, approximately 0.40 mm to 0.80 mm.

[0051] The second wire portion 22 and the fourth wire portion 24 are tapered portions whose diameters increase from the distal end toward the proximal end. The outer diameter of the distal end of the second wire portion 22 is approximately the same as the outer diameter of the proximal end of the first wire portion 21, and the outer diameter of the proximal end of the second wire portion 22 is approximately the same as the outer diameter of the distal end of the third wire portion 23. The outer diameter of the distal end of the fourth wire portion 24 is approximately the same as the outer diameter of the proximal end of the third wire portion 23, and the outer diameter of the proximal end of the fourth wire portion 24 is approximately the same as the outer diameter of the distal end of the fifth wire portion 25.

[0052] Because each portion of the knife wire 20 is configured in this manner, the rigidity of the knife wire 20 gradually increases from the distal end to the proximal end. For example, the rigidity of the second wire portion 22 is higher than the rigidity of the first wire portion 21, the rigidity of the third wire portion 23 is higher than the rigidity of the second wire portion 22, the rigidity of the fourth wire portion 24 is higher than the rigidity of the third wire portion 23, and the rigidity of the fifth wire portion 25 is higher than the rigidity of the fourth wire portion 24.

[0053] 8 shows the positional relationship between the knife wire 20 and the endoscope 200 when the incision instrument 100 is inserted into the treatment tool lumen 222 of the endoscope 200. More specifically, the positional relationship between the knife wire 20 and the endoscope 200 is shown in a state where the incision instrument 100 is inserted into the treatment tool lumen 222 and the portion of the exposed portion 20E of the knife wire 20 from the distal end position P1 to a predetermined distance L1 toward the proximal end (hereinafter referred to as the "protruding portion R2") protrudes from the opening 232 of the insertion section 220 of the endoscope 200 (hereinafter referred to as the "specific state"). The specific state is a standard state when a procedure is performed with the distal end of the incision instrument 100 inserted into the treatment tool lumen 222 of the endoscope 200 protruding from the opening 232 of the distal end 230 of the endoscope 200. The predetermined distance L1 is, for example, 44 mm.

[0054] FIG. 8 shows the portion of the knife wire 20 that is disposed within the bending portion 224 of the insertion section 220 of the endoscope 200 in the specific state (hereinafter referred to as the "bending portion inner portion R1"). As shown in FIG. 8 , in the specific state, the bending portion inner portion R1 that is disposed within the bending portion 224 of the endoscope 200 is composed of the proximal end of the first wire portion 21, the entire second wire portion 22, and the distal end of the third wire portion 23. Therefore, in the specific state, the distal end D2 of the second wire portion 22 is located distally of the proximal end of the bending portion inner portion R1 (bending portion 224). In this embodiment, in the specific state, the distal end D2 of the second wire portion 22 is located distally of the longitudinal center position of the bending portion inner portion R1 (bending portion 224). Furthermore, in the specific state, the distal end D2 of the second wire portion 22 is located proximally of the distal end of the bending portion inner portion R1 (bending portion 224).

[0055] In addition, in the specific state, the tip D3 of the third wire portion 23 is located more distal than the base end of the bending portion inner portion R1 (bending portion 224). In this embodiment, in the specific state, the tip D3 of the third wire portion 23 is located more proximal than the tip of the bending portion inner portion R1 (bending portion 224). In addition, the tip D4 of the fourth wire portion 24 is located more proximal than the base end of the bending portion inner portion R1 (bending portion 224).

[0056] (Effects of the Present Embodiment) As described above, the medical device 300 of the present embodiment includes the endoscope 200 having the insertion section 220 to be inserted into a subject, and the incision instrument 100 as an endoscopic treatment tool. The insertion section 220 of the endoscope 200 has a treatment tool lumen 222 that opens at the distal end 230 of the insertion section 220 and into which the incision instrument 100 is inserted, and a bending section 224 that is located closer to the proximal end than the distal end 230 and bends when bent. The incision instrument 100 has the tube 10 having the knife wire lumen 17L, the knife wire 20 housed in the knife wire lumen 17L, and the handle main body 42 as a support member that rotatably supports the proximal end of the knife wire 20. The knife wire 20 includes a first wire portion 21 including an exposed portion 20E that can be exposed on the outer periphery of the tube 10, and a second wire portion 22 that is located on the proximal side of the first wire portion 21 and has higher rigidity than the exposed portion 20E of the first wire portion 21. In a specific state in which the incision instrument 100 is inserted into the treatment tool lumen 222 of the endoscope 200 and a protruding portion R2, which is a portion of the exposed portion 20E of the knife wire 20 that is a predetermined distance L1 proximal to the tip position P1, is caused to protrude from the opening 232 of the insertion section 220 of the endoscope 200, the tip D2 of the second wire portion 22 is located distal to the proximal end of the bending portion 224 (bending portion inner portion R1).

[0057] Because the medical device 300 of this embodiment has this configuration, the orientation of the exposed portion 20E of the knife wire 20 can be smoothly changed to the desired orientation by rotating the handle main body 42, as described below.

[0058] 9 is an explanatory diagram showing the configuration of a knife wire 20X in a comparative example. Similar to the knife wire 20 of the first embodiment, the knife wire 20X in the comparative example includes a first wire portion 21 including an exposed portion 20E and a second wire portion 22 located proximal to the first wire portion 21 and having higher rigidity than the exposed portion 20E of the first wire portion 21. In the comparative example, in the specific state, the distal end D2 of the second wire portion 22 is located proximal to the proximal end of the bending portion 224 (bending portion inner portion R1). That is, in the specific state, only the first wire portion 21 of the knife wire 20X, which has a relatively low rigidity, is located in the bending portion 224 of the insertion section 220 of the endoscope 200. Therefore, when the curved portion 224 of the endoscope 200 is curved and the knife wire 20X of the incision instrument 100 housed in the treatment tool lumen 222 is curved, the rotational torque generated by rotating the handle main body 42 that supports the base end of the knife wire 20X is not transmitted well to the tip side at the portion of the knife wire 20X located at the curved portion 224, and the orientation of the exposed portion 20E of the knife wire 20X cannot be smoothly changed to the desired orientation.

[0059] In contrast, in the medical device 300 of the present embodiment, in the specific state, the tip D2 of the second wire portion 22 of the knife wire 20, which has higher rigidity than the first wire portion 21, is located distally of the proximal end of the bending portion 224 of the endoscope 200. That is, in the specific state, a portion of the knife wire 20 having higher rigidity than the first wire portion 21 is located at the bending portion 224 of the endoscope 200. Therefore, even when the bending portion 224 of the endoscope 200 is bent and the knife wire 20 is bent, the rotational torque generated by rotating the handle main body 42 is effectively transmitted to the distal end of the portion of the knife wire 20 located at the bending portion 224, thereby enabling the orientation of the exposed portion 20E of the knife wire 20 to be smoothly changed to a desired orientation. Therefore, with the medical device 300 of the present embodiment, the orientation of the exposed portion 20E of the knife wire 20 can be smoothly changed to a desired orientation by rotating the handle main body 42 while maintaining the inner and outer diameters of the tube 10 and the outer diameter of the knife wire 20.

[0060] Furthermore, in the medical device 300 of this embodiment, in the above-described specific state, the tip D2 of the second wire portion 22 of the knife wire 20 is located distally of the longitudinal center position of the bending portion 224 of the endoscope 200. That is, in the above-described specific state, a portion of the knife wire 20 with relatively high rigidity is located over more than half of the longitudinal direction of the bending portion 224 of the endoscope 200. Therefore, even when the bending portion 224 of the endoscope 200 is bent and the knife wire 20 is bent, the rotational torque generated by rotating the handle main body 42 is more effectively transmitted to the distal end of the portion of the knife wire 20 located at the bending portion 224, thereby enabling the orientation of the exposed portion 20E of the knife wire 20 to be changed to the desired orientation more smoothly.

[0061] In the medical device 300 of this embodiment, the first wire portion 21 of the knife wire 20 is cylindrical, and the second wire portion 22 is tapered, increasing in diameter from the distal end to the proximal end. Therefore, the medical device 300 of this embodiment can provide the second wire portion 22 with relatively high rigidity while suppressing the rigidity gap in the knife wire 20.

[0062] Furthermore, in the medical device 300 of this embodiment, the knife wire 20 includes a third wire portion 23 and a fourth wire portion 24. The third wire portion 23 is located proximal to the second wire portion 22, has higher rigidity than the distal end of the second wire portion 22, and is cylindrical. The fourth wire portion 24 is located proximal to the third wire portion 23, has higher rigidity than the distal end of the third wire portion 23, and is tapered with a diameter increasing from the distal end to the proximal end. In the specific state described above, the distal end of the third wire portion 23 is located distal to the proximal end of the bending portion 224, and the distal end of the fourth wire portion 24 is located proximal to the proximal end of the bending portion 224. Therefore, according to the medical device 300 of this embodiment, the fourth wire portion 24, which has a relatively large diameter, is not disposed in the bending portion 224 of the endoscope 200, and a decrease in the slidability of the incision instrument 100 in the treatment tool lumen 222 of the endoscope 200 can be suppressed.

[0063] Furthermore, in the medical device 300 of this embodiment, the minimum diameter of the exposed portion 20E of the knife wire 20 is 0.15 mm or more and 0.30 mm or less. Therefore, the medical device 300 of this embodiment can achieve both an improvement in the rotational torque transmissibility of the knife wire 20 and an improvement in the cutting ability of the knife wire 20.

[0064] B. Second Embodiment: Fig. 10 is an explanatory diagram showing the detailed configuration of the knife wire 20a in the second embodiment. In the following, among the configuration of the knife wire 20a in the second embodiment, the same components as those of the knife wire 20 in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0065] The knife wire 20a of the second embodiment includes, in order from the distal end to the proximal end, a first wire portion 21, a second wire portion 22a, a third wire portion 23a, and a fifth wire portion 25. The first wire portion 21 includes the exposed portion 20E. The length of the first wire portion 21 is, for example, approximately 60 mm to 80 mm, the length of the second wire portion 22a is, for example, approximately 45 mm to 65 mm, and the length of the third wire portion 23a is, for example, approximately 20 mm to 40 mm.

[0066] The first wire portion 21 and the fifth wire portion 25 are cylindrical portions with a substantially constant outer diameter. On the other hand, the second wire portion 22a and the third wire portion 23a are tapered portions whose diameters increase from the distal end toward the proximal end. The degree (gradient) of the diameter increase from the distal end toward the proximal end of the third wire portion 23a is greater than the degree (gradient) of the diameter increase from the distal end toward the proximal end of the second wire portion 22a. The outer diameter of the distal end of the second wire portion 22a is substantially the same as the outer diameter of the proximal end of the first wire portion 21, and the outer diameter of the proximal end of the second wire portion 22a is substantially the same as the outer diameter of the distal end of the third wire portion 23a. The outer diameter of the proximal end of the third wire portion 23a is substantially the same as the outer diameter of the distal end of the fifth wire portion 25.

[0067] Because each portion of the knife wire 20a is configured in this manner, the rigidity of the knife wire 20a gradually increases from the distal end to the proximal end. For example, the rigidity of the second wire portion 22a is higher than that of the first wire portion 21, the rigidity of the third wire portion 23a is higher than that of the second wire portion 22a, and the rigidity of the fifth wire portion 25 is higher than that of the third wire portion 23a.

[0068] In the specific state described above, the bending portion inner portion R1 disposed within the bending portion 224 of the endoscope 200 is composed of the base end of the first wire portion 21 and the tip end of the second wire portion 22a. Therefore, in the specific state, the tip D2 of the second wire portion 22a is located more distal than the base end of the bending portion inner portion R1 (bending portion 224). In this embodiment, in the specific state, the tip D2 of the second wire portion 22a is located more distal than the longitudinal center position of the bending portion inner portion R1 (bending portion 224).

[0069] In addition, in the specific state, the distal end D3 of the third wire portion 23a is located closer to the proximal end than the proximal end of the inner curved portion R1 (curved portion 224).

[0070] In the second embodiment, as in the first embodiment, in a specific state, the tip D2 of the second wire portion 22a is located further distal than the base end of the bending portion 224. Therefore, even when the bending portion 224 of the endoscope 200 is bent and the knife wire 20a is bent, the rotational torque generated by rotating the handle main body 42 is transmitted well to the distal end of the portion of the knife wire 20a located at the bending portion 224, and the orientation of the exposed portion 20E of the knife wire 20a can be smoothly changed to the desired orientation.

[0071] Furthermore, in the second embodiment, the knife wire 20a includes a third wire portion 23a. The third wire portion 23a is located proximal to the second wire portion 22a, has higher rigidity than the distal end of the second wire portion 22a, and is tapered such that its diameter increases from the distal end to the proximal end. In a specific state, the distal end D3 of the third wire portion 23a is located proximal to the proximal end of the bending portion 224. Therefore, according to the second embodiment, the third wire portion 23a, which has a relatively large diameter, is not disposed in the bending portion 224 of the endoscope 200, and a decrease in the slidability of the incision instrument 100 in the treatment tool lumen 222 of the endoscope 200 can be suppressed.

[0072] C. Third Embodiment: Fig. 11 is an explanatory diagram showing the detailed configuration of the knife wire 20b in a third embodiment. In the following, among the configuration of the knife wire 20b in the third embodiment, the same components as those of the knife wire 20 in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0073] The knife wire 20b of the third embodiment includes a first wire portion 21, a second wire portion 22b, and a third wire portion 23b, which are arranged in this order from the distal end to the proximal end. The first wire portion 21 includes the exposed portion 20E. The length of the first wire portion 21 is, for example, approximately 60 mm to 80 mm, and the length of the second wire portion 22b is, for example, approximately 75 mm to 95 mm.

[0074] The first wire portion 21 and the third wire portion 23b are cylindrical portions with a substantially constant outer diameter. On the other hand, the second wire portion 22b is a tapered portion whose diameter increases from the distal end to the proximal end. The outer diameter of the distal end of the second wire portion 22b is substantially the same as the outer diameter of the proximal end of the first wire portion 21, and the outer diameter of the proximal end of the second wire portion 22b is substantially the same as the outer diameter of the distal end of the third wire portion 23b.

[0075] Because each portion of the knife wire 20b is configured in this manner, the rigidity of the knife wire 20b gradually increases from the distal end to the proximal end thereof. For example, the rigidity of the second wire portion 22b is higher than the rigidity of the first wire portion 21, and the rigidity of the third wire portion 23b is higher than the rigidity of the second wire portion 22b.

[0076] In the specific state described above, the bending portion inner portion R1 disposed within the bending portion 224 of the endoscope 200 is composed of the base end of the first wire portion 21 and the tip end of the second wire portion 22b. Therefore, in the specific state, the tip D2 of the second wire portion 22b is located more distal than the base end of the bending portion inner portion R1 (bending portion 224). In this embodiment, in the specific state, the tip D2 of the second wire portion 22b is located more distal than the longitudinal center position of the bending portion inner portion R1 (bending portion 224).

[0077] In addition, in the specific state, the distal end D3 of the third wire portion 23b is located closer to the proximal end than the proximal end of the inner curved portion R1 (curved portion 224).

[0078] In the third embodiment, as in the first embodiment, in a specific state, the tip D2 of the second wire portion 22b is located further distal than the base end of the bending portion 224. Therefore, even when the bending portion 224 of the endoscope 200 is bent and the knife wire 20b is bent, the rotational torque generated by rotating the handle main body 42 is transmitted well to the distal side even in the portion of the knife wire 20b located at the bending portion 224, and the orientation of the exposed portion 20E of the knife wire 20b can be smoothly changed to the desired orientation.

[0079] Furthermore, in the third embodiment, the knife wire 20b includes a third wire portion 23b. The third wire portion 23b is located proximal to the second wire portion 22b, has higher rigidity than the distal end of the second wire portion 22b, and is cylindrical. In a specific state, the distal end D3 of the third wire portion 23b is located proximal to the proximal end of the bending portion 224. Therefore, according to the third embodiment, the third wire portion 23b, which has a relatively large diameter, is not disposed in the bending portion 224 of the endoscope 200, and a decrease in the slidability of the incision instrument 100 in the treatment tool lumen 222 of the endoscope 200 can be suppressed.

[0080] D. Example: Two incision instruments 100 were created using the knife wire 20 of the first embodiment diameter described above and the knife wire 20X of the comparative example. For each of the two incision instruments 100, a test was conducted to determine whether the orientation of the exposed portion 20E of the knife wire could be smoothly changed to a desired orientation. Specifically, the incision instrument 100 was inserted into the treatment tool lumen 222 of the endoscope 200, and the distal end of the incision instrument 100 was protruded from the opening 232 of the distal end 230 of the endoscope 200 to achieve the specific state described above. At this time, the predetermined distance L1 (see FIG. 8 ) defining the protruding portion R2 of the knife wire 20 was set to 44 mm. The bending portion 224 of the endoscope 200 was also bent so that the bending angle θ1 ( FIG. 2 ) was 60 degrees. In this state, the orientation of the exposed portion 20E of the knife wire 20 was changed by rotating the handle main body 42 of the incision instrument 100. The rotation angle of the handle main body 42 required to change the orientation of the exposed portion 20E of the knife wire 20 by 180 degrees was investigated.

[0081] In the incision instrument 100 made using the knife wire 20X of the comparative example, the handle main body 42 had to be rotated approximately six times to change the orientation of the exposed portion 20E of the knife wire 20X by 180 degrees. On the other hand, in the incision instrument 100 made using the knife wire 20 of the first exemplary diameter, the handle main body 42 had to be rotated approximately five times to change the orientation of the exposed portion 20E of the knife wire 20 by 180 degrees.

[0082] This test confirmed that if a configuration is adopted in which the tip D2 of the second wire portion 22 is positioned more distal than the base end of the bending portion 224 in a specific state, even when the bending portion 224 of the endoscope 200 is bent and the knife wire 20 is bent, the rotational torque generated by rotating the handle main body 42 is transmitted well to the distal side, and the orientation of the exposed portion 20E of the knife wire 20 can be smoothly changed to the desired orientation.

[0083] E. Modifications: The technology disclosed in this specification is not limited to the above-described embodiment, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0084] The configuration of the medical device 300 in the above embodiment is merely an example, and various modifications are possible. For example, in the above embodiment, the difference in rigidity between the various portions of the knife wire 20 is achieved by the difference in outer diameter, but the difference in rigidity between the various portions may be achieved by other means. For example, the difference in rigidity between the various portions of the knife wire 20 may be achieved by the difference in forming material, or by the difference in mechanical structure, such as between a wire and a rope.

[0085] In the above embodiment, in a specific state, the tip D2 of the second wire portion 22 of the knife wire 20 is located proximally of the tip of the curved portion 224, but the tip D2 of the second wire portion 22 may also be located distally of the tip of the curved portion 224.

[0086] In the above embodiment, the opening 232 of the treatment tool lumen 222 is formed on the outer peripheral surface of the tip portion 230 of the insertion section 220, but the opening 232 may also be formed on the tip surface of the tip portion 230. The treatment tool lumen 222 opening at the tip portion 230 of the insertion section 220 includes not only a form in which the treatment tool lumen 222 opens on the outer peripheral surface of the tip portion 230 of the insertion section 220, but also a form in which the treatment tool lumen 222 opens on another surface of the tip portion 230 (for example, the tip surface).

[0087] In the above embodiment, the cross section of each portion of the knife wire 20 is substantially circular, but the cross section of each portion of the knife wire 20 may have other shapes, such as a substantially oval or polygonal shape.

[0088] In the above embodiment, the tube 10 is formed with a knife wire lumen 17L, a device lumen 16L, and a liquid supply lumen 18L, but the device lumen 16L and / or the liquid supply lumen 18L may not be formed.

[0089] In the above embodiment, the exposed portion 20E of the knife wire 20 is always exposed to the outside of the tube 10, but the exposed portion 20E of the knife wire 20 only needs to be exposed to the outside of the tube 10 at least when the tube 10 is in a predetermined position (e.g., a position in which the tube is greatly curved), and does not need to be exposed to the outside at all times.

Claims

1. A medical device (300) comprising: an endoscope (200) having an insertion portion (220) to be inserted into a subject; and an endoscopic treatment tool (100), wherein the insertion portion (220) of the endoscope (200) comprises: a treatment tool lumen (222) that opens at a tip end (230) of the insertion portion (220) and into which the endoscopic treatment tool (100) is inserted; and a bending portion (224) that is located on the base end side of the tip end (230) and bends by a bending operation, and the endoscopic treatment tool (100) comprises: a tube (10) having a knife wire lumen (17L), knife wires (20, 20a, 20b) housed in the knife wire lumen (17L), and a support member (42) that rotatably supports a base end (29) of the knife wires (20, 20a, 20b), The knife wire (20, 20a, 20b) includes a first wire portion (21) including an exposed portion (20E) that can be exposed to the outer circumferential side of the tube (10), and a second wire portion (22, 22a, 22b) that is located on a base end side of the first wire portion (21) and has higher rigidity than the exposed portion (20E) of the first wire portion (21), a medical device (300) in which, in a specific state in which the endoscopic treatment tool (100) is inserted into the treatment tool lumen (222) and a portion of the exposed portion (20E) of the knife wire (20, 20a, 20b) exposed from the tube (10) from a tip position (P1) to a predetermined distance (L1) toward the base end is caused to protrude from the opening (232) of the insertion portion (220), a tip (D2) of the second wire portion (22, 22a, 22b) is located distal to the base end of the curved portion (224).

2. A medical device (300) as described in claim 1, wherein in the specific state, the tip (D2) of the second wire portion (22, 22a, 22b) is located distal to the longitudinal center position of the curved portion (224).

3. A medical device (300) as described in claim 1 or 2, wherein the first wire portion (21) is cylindrical, and the second wire portion (22, 22a, 22b) is tapered, the diameter of which increases from the tip side toward the base side.

4. A medical device (300) as described in claim 3, wherein the knife wire (20a) is located on the base end side of the second wire portion (22a), has higher rigidity than the tip end of the second wire portion (22a), and includes a tapered third wire portion (23a) which expands in diameter from the tip end side toward the base end side, and in the specific state, the tip (D3) of the third wire portion (23a) is located on the base end side of the base end of the curved portion (224).

5. A medical device (300) as described in claim 3, wherein the knife wire (20b) is located on the base end side of the second wire portion (22b), exhibits higher rigidity than the tip end of the second wire portion (22b), and includes a cylindrical third wire portion (23b), and in the specific state, the tip (D3) of the third wire portion (23b) is located on the base end side of the base end of the curved portion (224).

6. A medical device (300) as set forth in claim 3, wherein the knife wire (20) includes a cylindrical third wire portion (23) located on the base end side of the second wire portion (22) and having higher rigidity than the tip portion of the second wire portion (22), and a tapered fourth wire portion (24) located on the base end side of the third wire portion (23), having higher rigidity than the tip portion of the third wire portion (23) and expanding in diameter from the tip side toward the base end side, wherein in the specific state, the tip (D3) of the third wire portion (23) is located on the tip side of the base end of the curved portion (224), and the tip (D4) of the fourth wire portion (24) is located on the base side of the base end of the curved portion (224).

7. A medical device (300) as claimed in any one of claims 1 to 6, wherein the minimum diameter of the exposed portion (20E) of the knife wire (20, 20a, 20b) is greater than or equal to 0.15 mm and less than or equal to 0.30 mm.

8. An endoscopic treatment tool (100) used in combination with an endoscope (200) having an insertion portion (220) to be inserted into a subject, the insertion portion (220) of the endoscope (200) having: a treatment tool lumen (222) that opens at a tip end (230) of the insertion portion (220), and into which the endoscopic treatment tool (100) is inserted; and a bending portion (224) that is located on the base end side of the tip end (230) and bends by a bending operation, the endoscopic treatment tool (100) having: a tube (10) having a knife wire lumen (17L); knife wires (20, 20a, 20b) housed in the knife wire lumen (17L); and a support member (42) that rotatably supports a base end (29) of the knife wires (20, 20a, 20b), the knife wires (20, 20a, 20b) being an exposed portion (20E) of the knife wire (20, 20a, 20b) exposed from the tube (10) and a distal end (D2) of the second wire portion (22, 22a, 22b) is located on the distal end side of the tube (10) and has a rigidity higher than that of the exposed portion (20E) of the first wire portion (21); and 9. An endoscopic treatment instrument (100) as described in claim 8, wherein in the specific state, the tip (D2) of the second wire portion (22, 22a, 22b) is located on the tip side of the longitudinal center position of the bending portion (224).

10. An endoscopic treatment instrument (100) according to claim 8 or 9, wherein the first wire portion (21) is cylindrical, and the second wire portion (22, 22a, 22b) is tapered, the diameter of which increases from the tip side toward the base side.

11. An endoscopic treatment instrument (100) as described in claim 10, wherein the knife wire (20a) is located on the base end side of the second wire portion (22a), has higher rigidity than the tip end of the second wire portion (22a), and includes a tapered third wire portion (23a) which expands in diameter from the tip end side toward the base end side, and in the specific state, the tip (D3) of the third wire portion (23a) is located on the base end side of the base end of the curved portion (224).

12. An endoscopic treatment instrument (100) as described in claim 10, wherein the knife wire (20b) is located on the base end side of the second wire portion (22b), exhibits higher rigidity than the tip end of the second wire portion (22b), and includes a cylindrical third wire portion (23b), and in the specific state, the tip (D3) of the third wire portion (23b) is located on the base end side of the base end of the curved portion (224).

13. An endoscopic treatment instrument (100) as set forth in claim 10, wherein the knife wire (20) includes a cylindrical third wire portion (23) located on the base end side of the second wire portion (22) and having higher rigidity than the tip portion of the second wire portion (22), and a tapered fourth wire portion (24) located on the base end side of the third wire portion (23), having higher rigidity than the tip portion of the third wire portion (23) and expanding in diameter from the tip side toward the base end side, and wherein in the specific state, the tip (D3) of the third wire portion (23) is located on the tip side of the base end of the curved portion (224), and the tip (D4) of the fourth wire portion (24) is located on the base side of the base end of the curved portion (224).

14. An endoscopic treatment instrument (100) according to any one of claims 8 to 13, wherein the minimum value of the diameter of the exposed portion (20E) of the knife wire (20, 20a, 20b) is 0.15 mm or more and 0.30 mm or less.

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