Endoscopic Snare

Abstract

To provide a convenient endoscope snare.SOLUTION: An endoscope snare 1 includes: a tube-shaped sheath 10 with flexibility; an operation wire 20 inserted freely retractably in the sheath 10; and a loop-shaped snare loop 30 whose both ends are formed by a snare wire 31 connected to an end side of the operation wire 20. An end of the sheath 10 is provided with a hard-to-deform part 11 which is harder to plastically deformation and to elastically deform than the other parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an endoscopic snare that is inserted into an endoscope when in use. [Background technology]

[0002] Conventionally, an endoscopic snare has been known as an endoscopic treatment tool that is inserted through the forceps port of an endoscope to remove a lesion such as a polyp. This endoscopic snare has a snare loop made of a loop-shaped (ring-shaped) snare wire at the tip of an operating wire inserted into a tubular sheath, and this snare loop strangles (tightens) the lesion to remove it (see, for example, Patent Document 1).

[0003] There are two types of endoscopic snare procedures: the so-called hot snare (hot polypectomy), which uses a high-frequency current to cauterize the lesion, and the so-called cold snare (cold polypectomy), which mechanically removes the lesion using only the constricting force of the snare loop. Currently, hot snares are the mainstream, but recently the use of cold snares, which do not affect the tissue around the lesion due to heat, has been gradually increasing.

[0004] The excision of a lesion using a snare loop is performed by surrounding the lesion with the snare loop, then moving the sheath forward to house the proximal end of the snare loop within the sheath, gradually narrowing (reducing) the size of the loop outside the sheath. Therefore, when strangulating the lesion, a force is applied to the tip of the sheath by the snare loop in a direction that pushes open the opening, and a particularly large force is applied to the tip of the sheath in the case of a cold snare, which mechanically excises the lesion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-57418 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the sheath of an endoscopic snare is required to be flexible enough to bend along with the endoscope, as well as slidable enough to allow the inserted operating wire and snare wire to move smoothly forward and backward. Therefore, with conventional endoscopic snares, the distal end of the sheath can sometimes be significantly deformed and pushed out during strangulation. In such cases, it can be difficult to properly narrow the snare loop, which can lead to a loss of sharpness and hinder treatment.

[0007] In view of the above circumstances, the present invention aims to provide an easy-to-use snare for an endoscope. [Means for solving the problem]

[0008] The endoscopic snare of the present invention comprises: a flexible tubular sheath; an operating wire that is inserted into the sheath so as to be able to move forward and backward; a snare loop formed by a snare wire having both ends connected to the distal end side of the operating wire, a hard-to-deform portion that is less susceptible to plastic deformation than other portions and less susceptible to elastic deformation than other portions is provided at the distal end portion of the sheath; The non-deformable portion is formed by attaching a cylindrical reinforced sheath to the inner peripheral surface of the distal end of the sheath. Fixed or locked It consists of the reinforced sheath is made of a resin that is less susceptible to plastic deformation and less susceptible to elastic deformation than the material of the sheath; a connecting member that connects the operating wire and the snare wire; a handle having a main body to which a proximal end of the sheath is connected and a slider to which a proximal end of the operating wire is connected; Equipped with The connecting member is Through the stopper member of the handleThe slider is characterized in that when it abuts against the main body and is prevented from sliding further toward the distal end, it is located closer to the proximal end than the reinforced sheath.

[0009] According to the present invention, it is possible to prevent the sheath distal end from being significantly deformed and expanded during strangulation, which would otherwise cause the snare loop to lose its sharpness. This eliminates the need for adjustments such as increasing the operating force or amount to accommodate the deterioration of sharpness, and prevents problems such as hand shake that may accompany such adjustments. This allows the user to strangulate and resect the lesion with high precision and safety. In other words, the present invention provides an endoscopic snare that is easy to use.

[0010] In the present invention, the non-deformable portion is configured by disposing a cylindrical reinforced sheath at the tip of the sheath. will be done.

[0011] By arranging the reinforced sheath so that it directly contacts the snare wire, it is possible to construct a deformation-resistant portion at low cost and prevent deterioration of the sharpness due to compressive deformation of the sheath. Also, by making the inner diameter of the reinforced sheath smaller than the inner diameter of the sheath, it is possible to narrow the snare loop to a smaller width, further improving the sharpness of the snare loop.

[0012] In the present invention, the sheath is partially Transform It is preferable that the reinforced sheath has a locking portion formed in a shape that locks with the reinforced sheath.

[0013] This makes it possible to construct a less deformable portion at low cost while preventing problems such as the reinforced sheath falling off the sheath.

[0014] In the present invention, the reinforced sheath preferably has a spirally continuous convex portion on the inner peripheral surface or the surface facing the outer peripheral surface of the sheath.

[0015] This allows the reinforced sheath to be placed on the sheath while the locking portion is formed inexpensively using a procedure similar to that of a self-tapping screw.

[0016] The snare for an endoscope of the present invention further comprises a connecting member for connecting the operating wire and the snare wire, the connecting member comprising: When the slider abuts against the main body and is prevented from sliding further toward the tip side, Located on the proximal side of the reinforced sheath do.

[0017] This makes it possible to construct a non-deformable portion at low cost while preventing problems such as the connecting member getting caught on the reinforced sheath.

[0018] In the present invention, the axial length of the non-deformable portion is preferably at least 1 time the outer diameter of the snare wire and at most 10 times the outer diameter of the sheath.

[0019] This allows the non-deformable portion to stably contact the snare wire to receive the force, and prevents the non-deformable portion from impeding the flexibility of the sheath. [Effects of the Invention]

[0020] The endoscopic snare of the present invention can provide the excellent effect of being easy to use. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is an external view of an endoscopic snare according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the distal end of the sheath. [Figure 3] FIG. 10 is a diagram showing details of the shape of a snare loop. [Figure 4] FIG. 10 is a diagram showing the function of a snare loop. [Figure 5] FIG. 10 is a diagram showing the function of a snare loop. [Figure 6] FIG. 10 is a cross-sectional view showing another example of the configuration of the reinforced sheath. [Figure 7]10 is a cross-sectional view showing an example in which a locking portion that locks with a reinforced sheath is provided on the sheath. FIG. [Figure 8] 10 is a cross-sectional view showing an example in which a locking portion that locks with a reinforced sheath is provided on the sheath. FIG. [Figure 9] FIG. 10 is a cross-sectional view showing another example of the configuration of the snare loop. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is an external view of an endoscopic snare 1 according to one embodiment of the present invention. As shown in Fig. 1, the endoscopic snare 1 includes a sheath 10 that is inserted through the forceps port of an endoscope and passed through a forceps channel, a control wire 20 that is inserted so as to be able to move back and forth within the sheath, a snare loop 30 connected to the distal end of the control wire 20, a connecting member 40 that connects the control wire 20 and the snare loop 30, and a handle 50 to which the proximal ends of the sheath 10 and the control wire 20 are connected.

[0023] The sheath 10 is a flexible tubular member, the distal end of which is introduced into the vicinity of the lesion within the living body through the forceps channel of the endoscope. The sheath 10 is required to have flexibility to bend appropriately together with the endoscope, as well as slidability (low friction) to allow the operating wire 20 inserted therein to move smoothly forward and backward.

[0024] Therefore, in this embodiment, the sheath 10 is made of polytetrafluoroethylene (PTFE), a type of fluororesin that has appropriate flexibility and slidability. Also, in this embodiment, the distal end of the sheath 10 is provided with a non-deformable portion 11 that is configured to be less prone to deformation than the other portions (portions on the proximal end) of the sheath 10, thereby strengthening the distal end of the sheath 10. Details of the non-deformable portion 11 will be described later.

[0025] In this embodiment, the outer diameter D1 (see FIG. 2) of the sheath 10 is set to approximately 2.5 mm, the inner diameter D2 (see FIG. 2) to approximately 1.5 mm, and the overall length (length in the axial direction) to approximately 2350 mm, but these dimensions are not limited to these and appropriate dimensions can be used depending on the type and application of the endoscope to be used. Furthermore, the sheath 10 can be made of fluororesin other than PTFE, or various other resins.

[0026] The operating wire 20 connects the handle 50 and the snare loop 30 to operate the protrusion of the snare loop 30 from the sheath 10 and the retraction of the snare loop 30 into the sheath 10. In this embodiment, the operating wire 20 is made of a stranded wire made of stranded wires of SUS304, a type of stainless steel, but the operating wire 20 may also be made of a stranded wire of other metals such as various stainless steels or various titanium alloys, or may also be made of a solid wire of various metals.

[0027] In addition, in this embodiment, the outer diameter of the manipulation wire 20 is set to approximately 0.8 mm, but the outer diameter of the manipulation wire 20 is not limited to this, and an appropriate outer diameter can be adopted depending on the inner diameter D2 of the sheath 10, etc. The outer diameter of the manipulation wire 20, which is a stranded wire, is the diameter of a circumscribed circle in cross section.

[0028] The snare loop 30 is formed by folding back the snare wire 31, which is made of a stranded wire made of SUS304 wires, at the tip end to form a loop, and is used to strangle and excise the lesion. In this embodiment, the snare loop 30 is formed in a hexagonal shape, and can be housed within the sheath 10 by elastically deforming it by pushing open the bent portion, and can be expanded to its original hexagonal shape when protruded from the sheath 10 by the restoring force of the elastic deformation.

[0029] Furthermore, in this embodiment, the outer diameter of the snare wire 31 is set to approximately 0.35 mm, which is slightly smaller than half the outer diameter of the manipulation wire 20, but the outer diameter of the snare wire 31 is not limited to this, and an appropriate outer diameter can be adopted depending on the inner diameter D2 of the sheath 10, the outer diameter of the manipulation wire 20, etc. Here, the outer diameter of the snare wire 31, which is a stranded wire, is the diameter of a circumscribed circle in cross section, just like the manipulation wire 20.

[0030] In this embodiment, the configuration of the snare loop 30 is devised so that the entire snare loop 30 outside the sheath 10 is positioned on approximately the same plane even when the snare loop 30 is housed within the sheath 10 and the size of the loop is narrowed. The configuration of the snare loop 30 will be described in detail later.

[0031] The connecting member 40 is a cylindrical member made of SUS304, and connects the distal end of the operation wire 20 to both ends of the snare wire 31 (i.e., the proximal end of the snare loop 30). In this embodiment, the distal end of the operation wire 20 is inserted into the connecting member 40 from the proximal end side and crimped, and both ends of the snare wire 31 are inserted into the connecting member 40 from the distal end side and crimped, thereby connecting the operation wire 20 and the snare loop 30.

[0032] The connecting member 40 may connect the operation wire 20 and the snare wire 31 by brazing, or may connect the operation wire 20 and the snare wire 31 by using both crimping and brazing.

[0033] The handle 50 is gripped by a user such as a doctor to operate the advancement and retreat of the snare loop 30 relative to the sheath 10 (protrusion out of the sheath 10 and retraction into the sheath 10). The handle 50 includes a main body 51 to which the sheath 10 is connected, and a slider 52 to which the operating wire 20 is connected. In this embodiment, the main body 51 and the slider 52 are made of polycarbonate (PC).

[0034] The main body 51 has a U-shaped cross section and is provided with a groove 51a that extends continuously in the axial direction and accommodates the operating wire 20. A cap 51b that closes the groove 51a is fitted to the distal end of the main body 51, and the proximal end of the sheath 10 is connected to this cap 51b while being covered with a protective tube 51c. In this embodiment, this protective tube 51c is made of polyvinyl chloride (PVC), and by covering the proximal end of the sheath 10 over a predetermined range, it prevents the sheath 10 from being broken or damaged.

[0035] The slider 52 is loosely fitted onto the outer periphery of the main body 51 and is movable in the axial direction relative to the main body 51. As described above, the sheath 10 is connected to the main body 51 and the operation wire 20 is connected to the slider 52, and therefore, by moving the slider 52 relative to the main body 51, the operation wire 20 can be advanced or retreated relative to the sheath 10, and the amount of protrusion of the snare loop 30 from the sheath 10 can be changed.

[0036] Although detailed illustration is omitted, the operation wire 20 is connected to the slider 52 in a state in which it is inserted into a tubular support member 52a made of SUS304. This support member 52a has a length such that its tip protrudes slightly toward the tip from the cap 51b when the slider 52 is positioned at the base end of its movable range, and is intended to prevent bending of the operation wire 20 within the groove 51a and enable smooth advancement and retreat of the slider 52 and operation wire 20.

[0037] A cylindrical stopper member 53 made of PTFE is disposed between the slider 52 and the cap 51b in the groove 51a, and the support member 52a is inserted into this stopper member 53. That is, when the stopper member 53 is pressed by the slider 52 and abuts against the cap 51b, the slider 52 is positioned at the most distal end of its movable range, thereby setting the maximum protrusion amount of the snare loop 30. Note that FIG. 1 shows the state in which the slider 52 is positioned at the most distal end of its movable range, and the snare loop 30 is protruding to the maximum extent.

[0038] A ring 51d is provided on the base end (rear end) of the main body 51, into which the user inserts their thumb. Two rings 52b are provided on the slider 52, one on each side in a direction perpendicular to the axial direction of the main body 51, into which the user inserts, for example, the index finger and middle finger. This allows the handle 50 to be operated with one hand. The rings 51d abut against the slider 52 to set the base end position of the movable range and also function to prevent the slider 52 from slipping out.

[0039] The slider 52 is provided with an electrode 54 electrically connected to the operating wire 20 via a support member 52a. That is, the endoscopic snare 1 of this embodiment is configured to be capable of both hot snare and cold snare, and when hot snare is used, a high-frequency power source is connected to the electrode 54.

[0040] Figure 2 is an enlarged cross-sectional view of the distal end of the sheath 10, with the state of the snare loop 30 during strangulation indicated by a two-dot chain line. As shown in Figure 2, the non-deformable portion 11 is formed by placing a cylindrical reinforced sheath 12 made of a material that is less prone to deformation than PTFE inside the sheath 10 (the outer circumferential surface of the reinforced sheath 12 is fitted into the inner circumferential surface of the sheath 10). In this embodiment, the reinforced sheath 12 is made of polyether ether ketone (PEEK). PEEK is less prone to both plastic and elastic deformation than PTFE, so by placing the reinforced sheath 12 made of PEEK, the distal end of the sheath 10 can be made less prone to deformation.

[0041] The excision of a lesion using the snare loop 30 is performed by surrounding the lesion with the snare loop 30, then moving the sheath 10 forward to house the proximal end of the snare loop 30 within the sheath 10, gradually narrowing (reducing) the size of the loop outside the sheath 10. Therefore, when strangulating the lesion, as shown in Figure 2, a force is applied to the tip of the sheath 10 by the snare loop 30 in a direction that pushes open the opening, and a particularly large force is applied to the tip of the sheath 10 in the case of a cold snare that mechanically excises the lesion.

[0042] At this time, if the tip of the sheath 10 undergoes deformation, particularly large plastic deformation, the amount of squeezing of the snare loop 30 outside the sheath 10 relative to the amount of operation of the handle 50 (the amount of relative movement between the main body 51 and the slider 52) will decrease. Furthermore, since a force to deform the sheath 10 is required in addition to the force required to excise the lesion, the force required to operate the handle 50 (the force required for relative movement between the main body 51 and the slider 52) will increase.

[0043] Deformation of the distal end of the sheath 10 would deteriorate the sharpness of the snare loop 30. However, in this embodiment, this problem is prevented by providing a reinforced sheath 12 at the distal end of the sheath 10 and providing a deformation-resistant portion 11. As a result, in this embodiment, the sharpness of the snare loop 30 is maintained even when, for example, multiple lesions are strangulated and excised sequentially in a single procedure. Therefore, the user does not need to adjust the operating force or amount in response to deterioration in sharpness. This prevents problems such as hand shake that may accompany such adjustments, allowing for accurate and safe strangulation and excision of lesions. In other words, the endoscopic snare 1 of this embodiment is extremely easy to use when strangulating and excising lesions.

[0044] The material of the reinforced sheath 12 may be any material that is less susceptible to plastic deformation and less susceptible to elastic deformation than the material of the sheath 10. Specifically, the material of the reinforced sheath 12 may be any material that has a higher tensile yield stress and tensile modulus than the material of the sheath 10, and it is more preferable that the material have a higher compressive yield stress and compressive modulus than the material of the sheath 10.

[0045] Other than PEEK, other materials that can be used for the reinforced sheath 12 include acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS), polyvinyl chloride (PVC), polycarbonate (PC), polyphenylene sulfide (PPS), polysulfone (PSU), polyethylene terephthalate (PET), phenolic resin (PF), and epoxy resin (EP).Furthermore, the reinforced sheath 12 may be made of various resins to which glass fibers or the like have been added, fiber reinforced plastic (FRP), or metals such as stainless steel or titanium alloy.

[0046] The dimensions of the reinforced sheath 12 are not particularly limited, but in this embodiment, the outer diameter D3 of the reinforced sheath 12 is set to approximately 1.66 mm, slightly larger than the inner diameter D2 (approximately 1.5 mm) of the sheath 10, allowing the reinforced sheath 12 to be fixed by press-fitting, thereby improving productivity and reducing costs. In recent years, disposable medical instruments have been promoted to increase safety against various infectious diseases and reduce the burden of cleaning and disinfection in medical institutions, and the endoscopic snare 1 of this embodiment can be made into an inexpensive disposable product. Note that the outer diameter D1 of the sheath 10 at the non-deformable portion 11 increases by approximately 0.1 mm when the reinforced sheath 12 is press-fitted, but the change in outer diameter D1 is not shown in Figure 2.

[0047] In addition, in this embodiment, the inner diameter D4 of the reinforced sheath 12 is set to 1.26 mm, which is approximately 3.6 times the outer diameter of the snare wire 31, allowing smooth relative movement of the two snare wires 31 housed within the sheath 10 while preventing the snare wires 31 from being hindered from bending appropriately as described below.

[0048] Furthermore, in this embodiment, the axial length L1 of the non-deformable portion 11 (i.e., the axial length of the reinforced sheath 12) is set to approximately 5 mm to prevent the flexibility of the sheath 10 from being hindered by the reinforced sheath 12. In order not to hinder the flexibility of the sheath 10, the axial length L1 of the non-deformable portion 11 is preferably 10 times or less the outer diameter of the sheath 10, more preferably 5 times or less, and most preferably 2.5 times or less.

[0049] Furthermore, the lower limit of the axial length L1 of the difficult-to-deform portion 11 is determined by the strength of the material of the difficult-to-deform portion 11, the radial dimensions, and the dimensions at which the difficult-to-deform portion 11 will not be destroyed depending on the expected stress. However, in order to ensure stable contact with the snare wire 31 and withstand force, the axial length L1 of the difficult-to-deform portion 11 is preferably at least 1 time the outer diameter of the snare wire 31, more preferably at least 5 times, and most preferably at least 10 times.

[0050] The reinforced sheath 12 may be fixed to the sheath 10 by adhesive, welding, or the like. The non-deformable portion 11 may be formed by arranging the reinforced sheath 12 so as to cover the outer periphery of the sheath 10. In this embodiment, the reinforced sheath 12 is arranged so that the tip of the sheath 10 and the tip of the reinforced sheath 12 coincide with each other, but the tip of the sheath 10 and the tip of the reinforced sheath 12 do not have to coincide with each other.

[0051] Furthermore, by disposing the reinforced sheath 12 inside the sheath 10, it is possible to bring the reinforced sheath 12 into direct contact with the snare wire 31, thereby preventing deterioration of the sharpness of the sheath 10 due to compressive deformation (crushing). Furthermore, the reinforced sheath 12 reduces the inner diameter of the distal end of the sheath 10, making it possible to narrow the width of the snare loop 30 and improving the sharpness of the snare loop 30. Furthermore, if the reinforced sheath 12 is disposed so as to cover the outer periphery of the sheath 10, problems such as getting caught on the outlet of the forceps channel may occur, but this embodiment is designed to prevent such problems from occurring.

[0052] Fig. 3 is a diagram showing the details of the shape of the snare loop 30. Fig. 3 shows the snare loop 30 in its most protruding state and also shows a cross section of the sheath 10. The snare loop 30 is configured such that both ends of a single snare wire 31 are connected to the operating wire 20 via connecting members 40, and is bent at multiple points to form a hexagonal surrounding portion 30a that surrounds the lesion.

[0053] Specifically, the snare loop 30 comprises a pair of extension portions 32 extending from the connecting member 40 substantially in the axial direction of the operating wire 20, a pair of first inwardly convex bent portions 33 bent toward the outside of the snare loop 30 at the tips of the extension portions 32, a pair of first outwardly convex bent portions 34 bent toward the inside of the snare loop 30 at a position more distal than the first inwardly convex bent portions 33, a pair of second outwardly convex bent portions 35 bent toward the inside of the snare loop 30 at a position more distal than the first outwardly convex bent portions 34, a pair of second outwardly convex bent portions 36 bent toward the outside of the snare loop 30 at a position more distal than the second outwardly convex bent portions 35, and a tip fold portion 37 folded back at the most distal position of the snare loop 30.

[0054] In this embodiment, the length L2 of the extension portion 32 (the length of the snare wire 31 from the tip of the connecting member 40 to the first inward convex bend portion 33) is set to approximately 28 mm, the length L3 of the snare wire 31 from the first inward convex bend portion 33 to the first outward convex bend portion 34 is set to approximately 28 mm, the length L4 of the snare wire 31 from the first outward convex bend portion 34 to the second outward convex bend portion 35 is set to approximately 17 mm, the length L5 of the snare wire 31 from the second outward convex bend portion 35 to the second inward convex bend portion 36 is set to approximately 16 mm, and the length L6 of the snare wire 31 from the second inward convex bend portion 36 to the tip fold portion 37 is set to approximately 1.8 mm.

[0055] In this embodiment, the opening angle θ1 at the base end of the enclosing portion 30a (the opening angle from the pair of first inward convex bending portions 33 to the first outward convex bending portion 34) is set to approximately 54°, and the opening angle θ2 at the tip end of the enclosing portion 30a (the opening angle from the pair of second outward convex bending portions 35 to the second inward convex bending portion 36) is set to approximately 95°. The bending angle θ3 at the first inward convex bending portion 33 is set to approximately 153°, the bending angle θ4 at the first outward convex bending portion 34 is set to approximately 150°, and the bending angle θ5 at the second outward convex bending portion 35 is set to approximately 135°. Although reference numerals are omitted, the bending angle at the second inward convex bending portion 36 is set to approximately 150°, and the bending angle at the tip fold portion 37 is set to approximately 30°.

[0056] As a result, the longitudinal length L7 of the encircling portion 30a (the distance in the axial direction of the operating wire 20 between the first inward convex bent portion 33 and the second inward convex bent portion 36) is approximately 53 mm, the widthwise length L8 of the encircling portion 30a (the distance between the pair of first outward convex bent portions 34) is approximately 25 mm, and the distance L9 between the pair of second outward convex bent portions 35 is approximately 23 mm. Also, the distance L10 in the axial direction of the operating wire 20 between the second inward convex bent portion 36 and the tip folded portion 37 is approximately 1.7 mm. Note that the lengths or distances L2 to L10 are all lengths at the center of the snare wire 31 or distances between centers.

[0057] Furthermore, as shown in FIG. 3, in this embodiment, even when the snare loop 30 is in the most protruding state, the substantially entire extension portion 32 remains housed within the sheath 10.

[0058] 4A and 4B and 5A and 5B are diagrams showing the operation of the snare loop 30. In addition, in Figures 4A and 4B and 5A and 5B, the sheath 10 is shown in cross section, and the snare wire 31 is shown as a single wire for ease of understanding. Also, the state of the snare loop 30 shown in Figures 4A and 4B and 5A and 5B is not necessarily accurate, and some parts are exaggerated.

[0059] In this embodiment, the length L2 of the extension portion 32 and the length L3 from the first inward convex bend portion 33 to the first outward convex bend portion 34 are set longer than conventionally, so that the snare loop 30 is maintained on approximately the same plane during treatment.

[0060] As described above, the snare wire 31 and the operating wire 20 are made of a twisted wire made of twisted SUS304 wires, and the snare wire 31 has a smaller diameter than the operating wire 20, so it is difficult to connect the ends of the two wires while accurately aligning them, and there have been cases where the snare wire 31 and the operating wire 20 have been connected in an inclined or twisted state at the connection part (connecting member 40) with the operating wire 20. In such cases, not only has the snare loop 30 deviated significantly from the same plane, but the snare loop 30 has also been bent in an unexpected direction just before strangulation, hindering the treatment.

[0061] In this embodiment, the length L2 of the extension portion 32 is set to approximately 28 mm, which allows the snare wire 31 to bend appropriately at the extension portion 32 as shown in Fig. 4A, thereby preventing any tilt or twisting of the connecting member 40 from affecting the distal side of the first inward convex bent portion 33. In other words, the extension portion 32 bends based on the tilt or twisting of the connecting member 40, thereby absorbing these, and the portion distal side of the first inward convex bent portion 33 maintains an appropriate shape, allowing the snare loop 30 to be positioned on approximately the same plane.

[0062] Furthermore, in this embodiment, even when the snare loop 30 is in its most protruding state, substantially the entire extension portion 32 is housed within the sheath 10, so that the extension portion 32 is always loosely constrained and supported. In addition, by providing the reinforced sheath 12 and reducing the inner diameter of the distal end of the sheath 10, the constraining at the distal end of the sheath 10 is strengthened, and the two snare wires 31 are appropriately aligned. This more reliably maintains the snare loop 30 in an appropriate shape.

[0063] After the lesion is surrounded by the surrounding portion 30a, the sheath 10 is moved toward the distal end relative to the snare loop 30, causing the first inner convex bent portion 33 to be pushed open and housed within the sheath 10. Then, as shown in Fig. 4B, due to the restoring force of the elastic deformation of the snare wire 31, the pair of first inner convex bent portions 33 move past each other, causing the snare loop 30 to cross.

[0064] Specifically, the convex side of the first inward convex bent portion 33 abuts against the inner surface of the sheath 10, and a first intersecting portion 30b is formed at the base end side of the first inward convex bent portion 33 (i.e., at the extending portion 32), and a second intersecting portion 30c is formed at the distal end side of the first inward convex bent portion 33 (i.e., between the first inward convex bent portion 33 and the first outward convex bent portion 34). Furthermore, a distal abutting portion 30d is formed at the distal end side of the second intersecting portion 30c, abutting against the inner circumferential surface of the distal end of the sheath 10. At this time, twisting occurs in the snare wire 31 near the first inward convex bent portion 33 due to the intersection, but in this embodiment, the extending portion 32 is moderately bent to prevent large twisting.

[0065] Specifically, bending occurs so that a first abutment portion 30e is created where the snare loop 30 abuts against the inner surface of the sheath 10 proximal to the first intersection portion 30b, absorbing tilt and twisting of the snare loop 30, and the first abutment portion 30e is supported by the sheath 10, strengthening the restraining force that regulates tilt and twisting, thereby preventing large twisting from occurring due to the formation of the first intersection portion 30b and the second intersection portion 30c.

[0066] In addition, in conventional snare loops, twisting of the connection portion and twisting caused by the intersection could sometimes act synergistically, but in this embodiment, the first abutment portion 30e strengthens the restraining force between the connection member 40 and the first abutment portion 30e, so that twisting of the connection portion does not affect the area near the first inward convex bend portion 33.

[0067] 4B, the sheath 10 is further moved distally relative to the snare loop 30, causing the pair of first outwardly convex bent portions 34 to decrease the distance between them and approach the distal end of the sheath 10. If the twisting caused by the intersection near the first inwardly convex bent portion 33 affects the first outwardly convex bent portion 34 at this time, for example, both of the pair of first outwardly convex bent portions 34 may be twisted so that the rear side of the figure is convex, and in this case, the portion distal to the first outwardly convex bent portion 34 will be warped toward the front side of the figure.

[0068] In this embodiment, in addition to preventing warping by reducing twisting near the first inward convex bend portion 33 using the extension portion 32, the length L3 from the first inward convex bend portion 33 to the first outward convex bend portion 34 is set to approximately 28 mm, the same as that of the extension portion 32, thereby generating a moderate amount of bending between the first inward convex bend portion 33 and the first outward convex bend portion 34, as shown in Figure 5A, and preventing the above-mentioned twisting and resulting warping near the first outward convex bend portion 34.

[0069] Specifically, a gentle S-shaped bending occurs to the extent that a second abutment portion 30f where the snare loop 30 abuts against the inner circumferential surface of the sheath 10 is formed on the proximal side of the distal abutment portion 30d, thereby absorbing tilt and twisting of the snare loop 30 and strengthening the restraining force as the second abutment portion 30f is supported by the sheath 10, thereby reducing twisting in the vicinity of the first outwardly convex bent portion 34. As a result, even when the second outwardly convex bent portion 35 approaches the distal end of the sheath 10, the above-mentioned warping does not occur.

[0070] In the example shown in Figure 5A, a third intersection 30g occurs closer to the tip than the second intersection 30c, a fourth intersection 30h occurs closer to the tip than the third intersection 30g, and a second abutment 30f occurs between the second intersection 30c and the third intersection 30g. However, depending on the state of the snare loop 30, a deflection may occur that does not result in the third intersection 30g and the fourth intersection 30h.

[0071] 5A, when the sheath 10 is further moved toward the distal end relative to the snare loop 30, as shown in FIG. 5B, the first outer convex bent portion 34 is housed within the sheath 10. In this case, in this embodiment, in addition to the restraining force by the second abutting portion 30f, a third abutting portion 30i is generated where the snare loop 30 abuts against the inner circumferential surface of the sheath 10, for example, between the third intersection portion 30g and the fourth intersection portion 30h, thereby strengthening the restraining force between the first inner convex bent portion 33 and the distal abutting portion 30d, thereby reducing twisting in the vicinity of the first outer convex bent portion 34.

[0072] The first abutting portion 30e may be formed at least in one location at a portion of the extending portion 32 closer to the base end than the first intersecting portion 30b when the first inward convex bent portion 33 is housed in the sheath 10. In other words, the extending portion 32 may be set to a length that allows the extending portion 32 to bend so that any portion of the extending portion 32 abuts against the inner circumferential surface of the sheath 10 when the first inward convex bent portion 33 is housed in the sheath 10.

[0073] Furthermore, it is sufficient that at least one of the second abutting portion 30f and the third abutting portion 30i is formed immediately before the first outer convex bent portion 34 is housed within the sheath 10, and furthermore, as described above, the third intersection portion 30g and the fourth intersection portion 30h may not be formed depending on the manner of bending between the first inner convex bent portion 33 and the first outer convex bent portion 34. In other words, it is sufficient that the length between the first inner convex bent portion 33 and the first outer convex bent portion 34 is set to allow bending so that either portion abuts against the inner circumferential surface of the sheath 10 immediately before the first outer convex bent portion 34 is housed within the sheath 10 after the first inner convex bent portion 33 is housed within the sheath 10.

[0074] In this way, in this embodiment, by appropriately bending the extension portion 32 and the area between the first inward convex bent portion 33 and the first outward convex bent portion 34, not only is the snare loop 30 positioned on approximately the same plane when the snare loop 30 is in its most protruding state, but also when the size of the snare loop 30 outside the sheath 10 is narrowed, the snare loop 30 is maintained on approximately the same plane without warping or the like.

[0075] Furthermore, in this embodiment, there is no need to use a special connection method for connecting the operating wire 20 and the snare loop 30, nor is there any need to perform highly accurate positioning during connection, so there is no increase in manufacturing costs. In other words, the endoscopic snare 1 of this embodiment is an inexpensive disposable product that is very easy to use when strangulating and excising a lesion.

[0076] The length L2 of the extension portion 32 is not particularly limited, but in order to generate an appropriate degree of flexure, it is preferably 30 times or more the outer diameter of the snare wire 31, more preferably 50 times or more, and most preferably 70 times or more. Furthermore, the snare wire 31, which has a smaller diameter than the operating wire 20, stretches more easily than the operating wire 20 during strangulation, and the longer the extension portion 32, the greater the amount of stretch of the snare wire 31 during strangulation. Therefore, in order to reduce the amount of stretch of the snare wire 31 during strangulation and to convey an appropriate operating feel to the handle 50, the length of the extension portion 32 is preferably 200 times or less the outer diameter of the snare wire 31, more preferably 150 times or less, and most preferably 100 times or less.

[0077] Furthermore, the length L3 from the first inward convex bent portion 33 to the first outward convex bent portion 34 is not particularly limited, but in order to generate an appropriate degree of bending, it is preferably 20 times or more, more preferably 40 times or more, and most preferably 60 times or more the outer diameter of the snare wire 31. Furthermore, in order to configure the enclosing portion 30a with an easy-to-use size and shape, the length L3 from the first inward convex bent portion 33 to the first outward convex bent portion 34 is preferably 150 times or less, more preferably 130 times or less, and most preferably 100 times or less the outer diameter of the snare wire 31.

[0078] Furthermore, by setting the length L3 from the first inward convex bent portion 33 to the first outward convex bent portion 34 to be relatively long, it is possible to set the widthwise length L8 of the enclosing portion 30a to an easy-to-use size while also setting the bending angle θ3 at the first inward convex bent portion 33 and the bending angle θ4 at the first outward convex bent portion 34 to be relatively large. This reduces the restoring force of elastic deformation when the first inward convex bent portion 33 and the first outward convex bent portion 34 are housed in the sheath 10, enabling smooth operation, and also reduces the occurrence of twisting when the vicinity of the first inward convex bent portion 33 and the first outward convex bent portion 34 intersect.

[0079] Furthermore, in this embodiment, even when the snare loop 30 is in the state where it protrudes most from the sheath 10, substantially the entire extension portion 32 is accommodated within the sheath 10, but it is also possible to arrange for part or all of the extension portion 32 to protrude from the sheath 10 when the snare loop 30 is in the state where it protrudes most. However, in this case, the amount of operation of the handle 50 during strangulation increases. Therefore, from the viewpoint of operability, when the snare loop 30 is in the state where it protrudes most from the sheath 10, it is preferable that at least one-half of the length L2 of the extension portion 32 is accommodated within the sheath 10, more preferably at least two-thirds, and even more preferably at least three-quarters.

[0080] Furthermore, by ensuring that at least a portion of the extension portion 32 is contained within the sheath 10 even when the snare loop 30 is in its most protruding state from the sheath 10, and by ensuring that the connecting member 40 is positioned closer to the base end than the reinforced sheath 12 (does not reach the position of the reinforced sheath 12), it is possible to prevent the reinforced sheath 12 and the connecting member 40 from getting caught.

[0081] Furthermore, when the snare loop 30 is in a state where it protrudes most from the sheath 10, the first inward convex bent portion 33 may be accommodated within the sheath 10 together with the extending portion 32. This allows the first abutting portion 30e to generate a restraining force in the initial state of the snare loop 30 without requiring any operation by the user when performing strangulation, thereby more stably maintaining the snare loop 30 on a substantially same plane during treatment and improving the operability of the endoscopic snare 1. In this case, the first inward convex bent portion 33 may be located in the non-deformable portion 11, or may be located closer to the proximal end than the non-deformable portion 11 as shown in FIG. 4B .

[0082] Furthermore, in this embodiment, the inner diameter D2 of the sheath 10 is set to about 4.3 times the outer diameter of the snare wire 31, and the inner diameter D4 of the reinforced sheath 12 is set to about 3.6 times the outer diameter of the snare wire 31, but the inner diameter D2 of the sheath 10 and the inner diameter D4 of the reinforced sheath 12 may be set to other dimensions. However, in order to appropriately restrain the extension portion 32 while allowing it to bend appropriately, the inner diameter D2 of the sheath 10 and the inner diameter D4 of the reinforced sheath 12 are preferably 2.5 to 8 times the outer diameter of the snare wire 31, more preferably 3 to 6 times, and most preferably 3.5 to 5 times.

[0083] 6A to 6C are cross-sectional views showing other configuration examples of the reinforced sheath 12. As shown in FIG. 6A, the reinforced sheath 12 may have a flange portion 12a. In this case, it is possible to reliably prevent the position of the reinforced sheath 12 from shifting toward the proximal end of the sheath 10 when pressed by the snare wire 31 during strangulation. Alternatively, as shown in FIG. 6B, the reinforced sheath 12 may be configured as a bottomed cylinder having a bottom portion 12c with a through-hole 12b, and a tubular portion 12d disposed so as to cover the outer peripheral surface of the sheath 10. In this case, it is also possible to reliably prevent the position of the reinforced sheath 12 from shifting during strangulation. Alternatively, as shown in FIG. 6C, the reinforced sheath 12 may be configured as a ring or a cylinder and may be bonded or welded to the distal end surface of the sheath 10.

[0084] Furthermore, although not shown in the figures, the non-deformable portion 11 is not limited to being constructed by placing a separate reinforced sheath 12 at the tip of the sheath 10, but may also be constructed, for example, by partially mixing an additive such as glass fiber into the tip of the sheath 10, so that it is less susceptible to plastic deformation and elastic deformation than other portions.

[0085] 7A and 7B and 8A and 8B are cross-sectional views showing an example in which the sheath 10 is provided with a locking portion 13 that locks with the reinforced sheath 12. By providing the sheath 10 with the locking portion 13 and preventing the reinforced sheath 12 from falling off the sheath 10, the usability of the endoscopic snare 1 can be further improved.

[0086] 7A and 7B show a case in which a reinforced sheath 12 is placed inside a sheath 10, and then the distal end of the sheath 10 is heated and plastically deformed to form an engaging portion 13. In this example, as shown in Fig. 7A, the reinforced sheath 12 is first placed inside the sheath 10 at a position slightly proximal to the distal end. Then, a mold 100 heated by, for example, high-frequency induction heating is brought into axial contact with the distal end of the sheath 10 and pressed against it, thereby partially plastically deforming the distal end side of the reinforced sheath 12 of the sheath 10.

[0087] The mold 100 is configured in a shape that contacts the distal end surface and the distal end side of the outer peripheral surface of the sheath 10. When pressed and heated by the mold 100, the sheath 10 is crushed in the axial direction and plastically deformed so that the inner peripheral surface bulges toward the axis. Once the distal end of the sheath 10 has been appropriately deformed, the mold 100 is separated from the sheath 10, as shown in Fig. 7B, and the sheath 10 is cooled.

[0088] As a result, a locking portion 13 formed to bulge toward the axial center is provided at the distal end of the sheath 10. By locking the reinforced sheath 12 with the locking portion 13, movement of the sheath 10 toward the distal end is restricted, thereby preventing the reinforced sheath 12 from falling off the sheath 10.

[0089] In this way, by forming the locking portion 13 by partially plastically deforming the sheath 10 after placing the reinforced sheath 12 at the distal end of the sheath 10, it is possible to prevent the reinforced sheath 12 from falling off more easily and inexpensively than by methods such as bonding or welding. Furthermore, when the end surface of the sheath 10 is processed by chamfering, rounding, or the like, it is also possible to form the locking portion 13 at the same time.

[0090] When forming the locking portion 13, the amount of protrusion of the locking portion 13 (the inner diameter of the locking portion 13) may be limited by inserting a pin of an appropriate outer diameter into the sheath 10 and the reinforced sheath 12. Frictional heat or the like may be used to heat the sheath 10, or the sheath 10 may be plastically deformed only by pressing force without being heated. After forming the locking portion 13, the reinforced sheath 12 may be positioned by press-fitting or the like.

[0091] 8A and 8B show a case in which the engaging portion 13 is formed by partially plastically or elastically deforming the sheath 10 using the reinforced sheath 12. In this example, the reinforced sheath 12 has a flange portion 12a and a spirally continuous (thread-like) convex portion 12e on the outer circumferential surface of the portion that is inserted into the sheath 10. The outer diameter at the apex of this convex portion 12e is set to be slightly larger than the inner diameter of the sheath 10.

[0092] That is, the reinforced sheath 12 in this example is configured similarly to a self-tapping screw. Specifically, the reinforced sheath 12 in this example is configured so that, when it is screwed onto the distal end of the sheath 10 (inserted while being rotated around its axis), the protrusions 12e partially plastically or elastically deform the sheath 10, thereby forming the locking portion 13, which is a spiral groove.

[0093] As a result, the movement of the reinforced sheath 12 toward the distal end side of the sheath 10 is restricted by the engagement of the protrusion 12e and the engagement portion 13, and therefore, the reinforced sheath 12 is prevented from falling off from the sheath 10.

[0094] In this way, by providing a spirally continuous protrusion 12e on the surface of the reinforced sheath 12 facing the inner surface of the sheath 10 and using this protrusion 12e to partially deform the sheath 10 to form the locking portion 13, it is possible to prevent the reinforced sheath 12 from falling off easily and inexpensively compared to methods such as bonding or welding.

[0095] The apex of the protrusion 12e may be sharp, and the locking portion 13 may be formed by partially breaking the sheath 10. The protrusion 12e may be one or two or more. The reinforced sheath 12 may be configured to cover the outer peripheral surface of the sheath 10, and the protrusion 12e may be provided on the surface facing the outer peripheral surface of the sheath 10. The flange portion 12a may also be omitted.

[0096] In this example, the distal end of the inner peripheral surface of the reinforced sheath 12 is provided with a distal tapered section 12f that gradually widens in diameter toward the distal end, and a proximal tapered section 12g that gradually widens in diameter toward the proximal end, thereby improving the slidability of the snare wire 31, but the distal tapered section 12f and the proximal tapered section 12g may be omitted. Also, instead of the distal tapered section 12f and the proximal tapered section 12g, appropriate rounded sections may be provided.

[0097] Although not shown, the protrusions 12e may be continuous and discontinuous in a spiral shape. The shape and arrangement of the protrusions 12e may be any shape and arrangement that allows the sheath 10 to be appropriately deformed or broken to form the locking portion 13.

[0098] 9A and 9B are cross-sectional views showing other configuration examples of the snare loop 30. The snare loop 30 may not have the second outwardly convex bent portion 35, as shown in Fig. 9A, or may not have the first outwardly convex bent portion 34 and the second outwardly convex bent portion 35, as shown in Fig. 9B.

[0099] Although not shown, the shape of the enclosing portion 30a of the snare loop 30 is not particularly limited and may be, for example, a square, a heptagon, or other shapes. The enclosing portion 30a may be configured to have an asymmetrical shape, such as by providing the first outwardly convex bent portion 34 and the second outwardly convex bent portion 35 only on the right side of the figure in the example shown in FIG. 9B. In this embodiment, the portion distal to the second inwardly convex bent portion 36 is configured in a V-shape, but it may also be configured in a U-shape, for example. It goes without saying that the size of the snare loop 30 is not particularly limited.

[0100] Although the embodiments of the present invention have been described above, the endoscopic snare of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention. For example, the structure of the handle 50 is not limited to that shown in the above-described embodiments, and other known structures can be adopted. Furthermore, the snare loop 30 can have various known configurations.

[0101] Furthermore, the actions and effects shown in the above-described embodiments are merely a list of the most preferable actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to these. [Explanation of symbols]

[0102] 1 Endoscopic snare 10 Sheath 11. Hard-to-deform part 12 Reinforced sheath 12e Convex part 13 Locking part 20 Control wire 30 snare loops 31 Snare wire 40 Connecting member D1 Sheath outer diameter L1 Axial length of the difficult-to-deform part

Claims

1. a flexible tubular sheath; an operating wire that is inserted into the sheath so as to be able to move forward and backward; a snare loop formed by a snare wire having both ends connected to the distal end side of the operating wire, a hard-to-deform portion that is less susceptible to plastic deformation than other portions and less susceptible to elastic deformation than other portions is provided at the distal end portion of the sheath; the non-deformable portion is configured by fixing or engaging a cylindrical reinforced sheath to an inner circumferential surface of the distal end portion of the sheath, the reinforced sheath is made of a resin that is less susceptible to plastic deformation and less susceptible to elastic deformation than the material of the sheath; a connecting member that connects the operating wire and the snare wire; a handle having a main body to which a proximal end of the sheath is connected and a slider to which a proximal end of the operating wire is connected; Equipped with An endoscopic snare characterized in that the connecting member is located closer to the base end than the reinforced sheath when the slider abuts against the main body via the stopper member of the handle, preventing further sliding toward the tip.

2. The endoscopic snare according to claim 1, The snare for an endoscope is characterized in that the sheath has an engaging portion formed into a shape that engages with the reinforced sheath by partially deforming the sheath.

3. The endoscopic snare according to claim 2, The reinforced sheath has a spirally continuous convex portion on the inner surface or the surface facing the outer surface of the sheath.

4. The endoscopic snare according to any one of claims 1 to 3, An endoscopic snare, characterized in that the axial length of the non-deformable portion is at least 1 time the outer diameter of the snare wire and not more than 10 times the outer diameter of the sheath.

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