Snare drum

Abstract

The present invention provides a snare drum that can effectively transmit the rotational force applied to the base end to the loop section located at the tip end. [Solution] A snare 10 for capturing or retrieving an object 200 inside a blood vessel, comprising: a core wire 20 extending in the longitudinal direction from tip to base; a snare loop 30 having a loop portion 31 formed of a flexible snare wire 40 on the tip side of the core wire 20; and a cylindrical member 70 arranged to cover the tip of the core wire 20 and the first wire end 41 and second wire end 42 of the snare wire 40, wherein the cylindrical member 70 is a strand coil 71 formed by twisting together two or more strands.

Description

Technical Field

[0001] The present invention relates to a snare for retrieving an object within a blood vessel.

[0002] In order to retrieve an object such as a foreign body within a blood vessel, a snare is used. The snare has a loop portion at the tip of a long core wire (see, for example, Patent Document 1). When using the snare, the operator reaches the target position with the loop portion housed in the sheath, and expands the loop portion by protruding the loop portion from the sheath. Next, the operator hooks the loop portion on the object and gradually houses the loop portion into the sheath. As a result, the size of the loop portion becomes smaller, and the object is gripped between the loop portion and the tip of the sheath. In this state, the operator pulls the sheath and the snare to house the object in the lumen of the guiding catheter, and retrieves the object outside the body through the lumen of the guiding catheter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When housing an object in the lumen of the guiding catheter, the operator may rotate the snare. For example, when retrieving a stent that has fallen off in the coronary artery with a snare, if the end of the stent catches on the tip of the guiding catheter, it becomes necessary to retrieve the stent together with the guiding catheter outside the body. In order to avoid such a situation, the operator rotates the proximal end portion of the snare and houses it in the lumen of the guiding catheter while adjusting the position of the stent.

[0005] However, if the snare cannot adequately transmit the rotational force applied to its proximal end to the loop at its tip, the surgeon will need to rotate the snare multiple times. This can result in damage to vulnerable parts of the snare or increased patient burden due to prolonged procedure time.

[0006] The present invention was made to solve the above-mentioned problems, and aims to provide a snare that can effectively transmit the rotational force applied to the base end to the loop portion located at the tip end. [Means for solving the problem]

[0007] The above objective is achieved by the invention described in (1) below. (1) The snare according to the present invention is a snare for capturing or retrieving an object in a blood vessel, comprising: a core wire extending in the longitudinal direction from tip to base; a snare loop having a loop portion formed of a flexible snare wire on the tip side of the core wire; and a cylindrical member disposed to cover the tip of the core wire and the first and second wire ends of the snare wire, wherein the cylindrical member is a strand coil formed by twisting together two or more strands. [Effects of the Invention]

[0008] In the snare described in (1) above, the strand coil has the flexibility and high torsional strength required for a snare, so it can effectively transmit the rotational force applied to the base end of the core wire to the snare loop. Furthermore, compared to a coil made of a single strand, the strand coil is less prone to deformation such as an increase in outer diameter due to loosening of the winding when the snare is rotated, and can maintain its shape. As a result, the snare can suppress the increase in sliding resistance when passing through the vessel or sheath.

[0009] (2) In the snare described in (1) above, the tip of the core wire includes a tapered portion in which the outer diameter increases from the tip to the base, and the snare wire may be fixed to the tapered portion of the core wire. This allows the rotational force applied to the base end of the core wire to be transmitted more effectively to the loop portion located on the tip side.

[0010] (3) In the snare described in (1) or (2) above, one of the first wire end and the second wire end may be positioned closer to the base end than the other. This allows the space between the strand coil and the tapered portion of the core wire, which gradually decreases in size toward the base end, to be effectively filled by the first wire end and the second wire end, which are positioned at different locations in the longitudinal direction. As a result, the snare suppresses the reduction in diameter of the strand coil due to the rotational force applied to the base end of the core wire, and improves the transmission of rotational force.

[0011] (4) In the snare described in any one of (1) to (3) above, the snare loop is provided with a snare coil that covers the outer circumference of the snare wire, and the strand coil may cover the first coil end and the second coil end of the snare coil. This increases the contact area between the snare loop and the object, thereby improving the gripping force. In addition, the snare can effectively transmit the rotational force applied to the base end to the snare loop via the snare coil covered by the strand coil.

[0012] (5) In the snare described in (4) above, the first wire end may be located closer to the base end than the first coil end, and the second wire end may be located closer to the base end than the second coil end. This allows the snare to more effectively fill the space between the strand coil, which gradually decreases in size towards the base end, and the tapered portion of the core wire. As a result, the snare suppresses the reduction in diameter of the strand coil due to the rotational force applied to the base end of the core wire, and further improves the transmission of rotational force.

[0013] (6) In the snare described in any one of (1) to (5) above, the snare wire is made of a stranded wire formed by twisting together two or more strands, and the winding direction of the snare wire may coincide with the winding direction of the strand coil. This allows the snare to mesh well with the strand coil and the snare wire, improving the transmission of rotational force when rotating in a direction that tightens the winding of each strand of the strand coil and the snare wire.

[0014] (7) In the snare described in any one of (1) to (6) above, the snare loop may have a tip coating layer on the surface facing outward of the loop portion that is more lubricating than the surface facing inward. This reduces sliding resistance when the snare passes through a vascular vessel or when the loop portion is housed in the sheath. Furthermore, since the loop portion has a portion on the surface facing inward of the loop portion that is less lubricating than the tip coating layer, the object can be gripped securely by the loop portion without slipping when gripping the object. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows the curved portion of the snare according to the first embodiment extended in a straight line, with the cylindrical member, fixing portion, and tip covering layer shown in cross-section, and the other members shown in plan view. [Figure 2] This is a plan view showing a snare according to the first embodiment, where (A) shows the state before the loop portion grips the object, and (B) shows the state after the loop portion grips the object. [Figure 3] This is a cross-sectional view along line AA in Figure 1. [Figure 4] This figure shows a modified example of the snare according to the first embodiment, with the bent portion of the snare extended in a straight line, and the cylindrical member, fixing portion and tip covering layer shown in cross-section, and the other members shown in plan view. [Figure 5] This figure shows another modified example of the snare according to the first embodiment, with the cylindrical member, fixing part and tip covering layer shown in cross-section and the other members shown in plan. [Figure 6]It is a diagram for explaining a method of forming a tip coating layer on a loop portion. (A) shows a state in which an expander is disposed inside the loop portion, (B) shows a state in which the expander is expanded to mask the inner surface of the loop portion, (C) shows a state in which the loop portion is dipped in a solution containing the material for the tip coating layer, and (D) shows a state in which the solution adhered to the loop portion is dried to form the tip coating layer. [Figure 7] It is a diagram showing, in cross section, the bent portion of the snare according to the second embodiment extended linearly, the cylindrical member, the fixing portion, and the tip coating layer, and showing, in plan view, the other members. [Figure 8] It is a cross-sectional view taken along line B-B of FIG. 7.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensional ratios in the drawings may be exaggerated for convenience of explanation and may differ from the actual ratios. In the following description, the side where the snare 10 is operated will be referred to as the "base end side", and the side inserted into the living body will be referred to as the "tip side".

[0017] <First Embodiment> The snare 10 according to the first embodiment of the present invention is a medical device that is inserted into a blood vessel together with a sheath 90 and used to capture or retrieve an object 200 such as a foreign body in the blood vessel.

[0018] As shown in FIGS. 1 to 3, the snare 10 includes a core wire 20 extending in the longitudinal axis direction from the tip to the base end, a snare loop 30 disposed on the tip side of the core wire 20, a cylindrical member 70 covering the tip portion of the core wire 20 and the base end portion of the snare loop 30, and a fixing portion 80 for fixing a plurality of members. The total length of the snare 10 in the longitudinal axis direction is, for example, 900 mm to 2600 mm.

[0019] The core wire 20 includes a base end core wire 21 located on the base end side and a tip core wire 22 located on the tip side. The base end core wire 21 and the tip core wire 22 are joined at a joining portion 23. The core wire 20 includes a base end coating layer 28 covering the surface.

[0020] The proximal core wire 21 is a member located on the proximal end side of the core wire 20 and operated by the operator. The outer diameter of the proximal core wire 21 is substantially constant. The proximal core wire 21 preferably has high rotational force transmission, high pushing-in property, and high operability, and can be formed of, for example, stainless steel. The distal core wire 22 is an elongated member extending from the distal end of the proximal core wire 21 in the distal direction. The distal core wire 22 preferably has high elasticity and high durability, and can be formed of, for example, a shape memory alloy (superelastic alloy) such as a Ni-Ti alloy. The distal core wire 22 has a first constant outer diameter portion 24 joined to the proximal core wire 21, a proximal tapered portion 25 whose outer diameter decreases from the distal end of the first constant outer diameter portion 24 in the distal direction, a second constant outer diameter portion 26 extending from the distal end of the proximal tapered portion 25 in the distal direction with a substantially constant outer diameter, and a tapered portion 27 whose outer diameter decreases from the distal end of the second constant outer diameter portion 26 in the distal direction.

[0021] The proximal coating layer 28 is a layer covering the surfaces of the proximal core wire 21 and the distal core wire 22. The proximal coating layer 28 is formed of a polymer material having low friction, such as polytetrafluoroethylene (PTFE), for example.

[0022] The total length of the core wire 20 in the longitudinal direction is, for example, 899 mm to 2599 mm, and is, for example, 1800 mm as an example. The length in the longitudinal direction from the joint portion 23 to the proximal end of the tapered portion 27 is, for example, 30 mm to 370 mm, and is, for example, 330 mm as an example. The length in the longitudinal direction from the proximal end of the tapered portion 27 to the distal end of the core wire 20 is, for example, 30 mm to 150 mm, and is, for example, 60 mm as an example. The outer diameter of the proximal end portion of the core wire 20 (the portion provided with the proximal coating layer 28 on the surface of the proximal core wire 21) is, for example, 0.3 mm to 1.0 mm, and is, for example, 0.36 mm as an example. The outer diameter of the second constant outer diameter portion 26 is, for example, 0.2 mm to 0.85 mm, and is, for example, 0.245 mm as an example. The outer diameter of the distal end of the core wire 20 is, for example, 0.05 mm to 0.2 mm, and is, for example, 0.08 mm as an example.

[0023] The snare loop 30 has a loop-shaped loop portion 31 for gripping the object 200, a bent portion 32 that bends at approximately 90 degrees with respect to the long axis of the core wire 20 at the base end of the loop portion 31, and a connecting portion 33 that is approximately parallel to the long axis of the core wire 20 at the base end of the bent portion 32. The loop portion 31 has a snare tip portion 35 located at the tip of the snare loop 30, and a wide portion 34 where the two wires extending from the bent portion 32 toward the snare tip portion 35 are furthest apart. The inner diameter of the loop portion 31 is, for example, 2 mm to 30 mm, and is 4 mm as an example. At the tip of the loop portion 31, the distance between the two wires forming the loop portion 31 gradually decreases from the wide portion 34 toward the snare tip portion 35, and it protrudes toward the tip. The plane on which the loop portion 31 expands is approximately perpendicular to the long axis of the tip of the core wire 20, as shown in Figure 2(A).

[0024] As shown in Figures 1-3, the snare loop 30 comprises a flexible snare wire 40 and a snare coil 50 that covers the outer circumference of the snare wire 40. The snare loop 30 also includes a tip covering layer 60 that covers at least a portion of its surface.

[0025] The snare wire 40 has a first wire end 41 and a second wire end 42, with a loop formed between the first wire end 41 and the second wire end 42. The first wire end 41 and the second wire end 42 of the snare wire 40 are inserted into the lumen of the cylindrical member 70 from the tip side of the cylindrical member 70, and the straight portion of the snare wire 40 including the first wire end 41 and the straight portion including the second wire end 42 are arranged along the tip of the core wire 20, substantially parallel to the long axis of the core wire 20. The first wire end 41 is positioned further back towards the base (or tip) than the second wire end 42. The first wire end 41 and the second wire end 42 are positioned to overlap with the tapered portion 27 of the core wire 20 in the long axis direction. The length in the long axis direction from the tip of the cylindrical member 70 to the first wire end 41 is, for example, 15 mm to 30 mm, and is 25 mm as an example. The length in the longitudinal direction from the tip of the cylindrical member 70 to the second wire end 42 is, for example, 15 mm to 30 mm, and is 20 mm as an example. The length in the longitudinal direction between the first wire end 41 and the second wire end 42 is, for example, 1 mm to 10 mm, preferably 2 mm to 5 mm, and is 5 mm as an example. The positions in the longitudinal direction of the first wire end 41 and the second wire end 42 may coincide.

[0026] The snare wire 40 is a stranded wire formed by twisting together multiple strands. The number of strands forming the snare wire 40 is preferably two or more, and more preferably four to seven. For example, the snare wire 40 is a stranded wire formed by twisting together seven strands, each formed by spirally winding six strands around one strand in the same direction. The strands of the snare wire 40 are made of, for example, a shape memory alloy such as a Ni-Ti alloy or stainless steel. The outer diameter of the stranded wire of the snare wire 40 is, for example, 0.05 mm to 0.4 mm, and 0.1 mm as an example. The outer diameter of the strands of the snare wire 40 is, for example, 0.014 mm to 0.13 mm, and 0.03 mm as an example. By being formed as a stranded wire, the snare wire 40 has high strength and high flexibility. Therefore, the snare wire 40 can deform flexibly when pulled into the sheath 90, reducing the sliding resistance between it and the sheath 90, thus suppressing damage to both the snare wire 40 and the sheath 90. In addition, since the snare wire 40 is formed by winding strands of wire in a spiral shape, the uneven surface of the stranded wire bites into the object, creating an anchoring effect, allowing the object 200 to be gripped without slipping.

[0027] The snare wire 40 may also be formed from a single strand, as shown in the modified example in Figure 4.

[0028] As shown in Figures 1-4, the snare coil 50 is a component that imparts X-ray opacity to the snare loop 30, and is a coil that covers the outer circumference of the snare wire 40 at the loop portion 31, the bent portion 32, and the tip portion of the connecting portion 33 of the snare loop 30. The coil wires forming the snare coil 50 are made of X-ray opacity materials such as Au, Pt, Pt-Ni alloy, and Pt-Ir alloy. The snare coil 50 has a first coil end 51 and a second coil end 52 at the connecting portion 33 of the snare loop 30. The first coil end 51 is positioned further forward than the first wire end 41 of the snare wire 40 and surrounds the straight portion further forward than the first wire end 41. The second coil end 52 is positioned further forward than the second wire end 42 of the snare wire 40 and surrounds the straight portion further forward than the second wire end 42. The first coil end 51 and the second coil end 52 are held stably by being positioned within the lumen of the cylindrical member 70. Alternatively, the first coil end 51 and / or the second coil end 52 may not be positioned within the lumen of the cylindrical member 70, but rather positioned towards the tip of the cylindrical member 70.

[0029] The coil wires forming the snare coil 50 are preferably wound loosely so that there are gaps between adjacent coil wires. However, the snare coil 50 may also be wound tightly so that there are no gaps between adjacent coil wires. The outer diameter of the coil wires of the snare coil 50 is, for example, 0.02 mm to 0.08 mm, with 0.02 mm being one example. The coil outer diameter of the snare coil 50 is, for example, 0.09 mm to 0.5 mm, with 0.14 mm being one example.

[0030] The tip coating layer 60 is a component that provides lubrication to the snare loop 30 and a part of the snare 10 located on the base end side of the snare loop 30 (for example, the cylindrical member 70, the fixing part 80, and the tip of the core wire 20). Preferably, the tip coating layer 60 is arranged on the surface facing outward of the loop portion 31 and not on the surface facing inward of the loop portion 31. Here, the inside of the loop portion 31 is the side where the space for gripping the object 200 is formed, and the outside of the loop portion 31 is the opposite side of the inside of the loop portion 31.

[0031] By positioning the tip coating layer 60 on the outside of the loop portion 31, the sliding resistance of the loop portion 31 when passing through the blood vessel or when housing the loop portion 31 in the sheath 90 can be reduced. By not positioning the tip coating layer 60 on the inside of the loop portion 31, the loop portion 31 can reliably grip the object 200 without slipping when gripping the object 200 with the loop portion 31. The tip coating layer 60 may also be positioned on the inside of at least a portion of the loop portion 31 closer to the base end than the wide portion 34 (for example, the portion close to the bent portion 32 of the loop portion 31). When gripping the object 200 with the loop portion 31, the inside of the base end of the loop portion 31 is less likely to come into contact with the object 200. Therefore, even if the tip coating layer 60 is positioned on the inside of the base end of the loop portion 31, the object 200 is less likely to slip from the loop portion 31.

[0032] Furthermore, it is preferable that the tip coating layer 60 is also positioned on the surface on the side perpendicular to the plane of the loop portion 31 (the vertical direction of the paper in Figure 3). This further reduces the sliding resistance of the loop portion 31 when it passes through the vascular or when it is housed in the sheath 90. Therefore, it is preferable that the tip coating layer 60 be positioned in a range of more than 180 degrees but less than 360 degrees in a cross section perpendicular to the long axis of the snare wire 40 forming the loop portion 31, so as to include the outside and vertical sides of the loop portion 31.

[0033] The tip coating layer 60 is preferably formed of a hydrophilic polymer material. Examples of hydrophilic polymer materials for forming the tip coating layer 60 include cellulose-based polymers, polyethylene oxide-based polymers, maleic anhydride-based polymers (for example, maleic anhydride copolymers such as methyl vinyl ether-maleic anhydride copolymer), acrylamide-based polymers (for example, polyacrylamide, glycidyl methacrylate-dimethylacrylamide block copolymer), water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, and their derivatives.

[0034] The cylindrical member 70 is a cylindrical member positioned to cover the tip of the core wire 20 and the first wire end 41 and second wire end 42 of the snare wire 40. The cylindrical member 70 further covers the first coil end 51 and second coil end 52 of the snare coil 50. However, the cylindrical member 70 does not necessarily have to cover the first coil end 51 and second coil end 52 of the snare coil 50. The tip of the cylindrical member 70 is located near the tip of the core wire 20 in the longitudinal direction, and the base end of the cylindrical member 70 overlaps with the second constant outer diameter portion 26 on the base end side of the tapered portion 27 of the core wire 20 in the longitudinal direction.

[0035] In this embodiment, the cylindrical member 70 is a strand coil 71 formed by twisting together a plurality of individual wires. The strand coil 71 is formed by spirally winding a plurality of coil wires arranged substantially parallel to each other. Note that the cylindrical member 70 may be a tubular body instead of a coil.

[0036] The winding direction of the strand coil 71 is preferably the same as the winding direction of the snare wire 40. However, the winding direction of the strand coil 71 does not have to be the same as the winding direction of the snare wire 40. Furthermore, the winding direction of the strand coil 71 is preferably clockwise from the base end to the tip end. When the operator operates the snare 10 with their right hand, the direction in which the snare 10 is easiest to rotate is clockwise when viewed from the base end of the snare 10. Therefore, by setting the winding direction of the strand coil 71 to clockwise and matching it to the direction in which the winding of the strand coil 71 tightens when operated with the right hand, the rotational force transmission of the snare 10 is improved. However, the winding direction of the strand coil 71 is also counterclockwise from the base end to the tip end.

[0037] The strand coil 71 has a loosely wound tip section 72 and a loosely wound base section 73, where the coil wires are loosely wound at the tip and base sections, respectively, with gaps between adjacent coil wires. The loosely wound tip section 72 and the loosely wound base section 73 are fixed to the core wire 20 by a fixing section 80, which will be described later. At this time, the material forming the fixing section 80 enters the lumen of the strand coil 71 through the gaps between adjacent coil wires in the loosely wound tip section 72 and the loosely wound base section 73 of the strand coil 71. As a result, the snare 10 can more effectively transmit the rotational force applied to the base end of the core wire 20 to the tip side because the strand coil 71 is firmly fixed to the core wire 20. Furthermore, it is preferable that the axial length of the loosely wound tip section 72 is longer than the axial length of the loosely wound base section 73. As a result, the flexibility of the strand coil 71 is improved without impairing the rotational force from the handle, thus improving its passability within the blood vessel. The total length in the longitudinal direction of the loosely wound tip portion 72 of the strand coil 71 is, for example, 10 mm to 50 mm, and is 20 mm as an example. The total length in the longitudinal direction of the loosely wound base portion 73 of the strand coil 71 is, for example, 1 mm to 10 mm, and is 5 mm as an example. The loosely wound tip portion 72 and the loosely wound base portion 73 of the strand coil 71 may be formed by processing the strand coil 71, such as electropolishing, as shown in the modified example in Figure 5. By electropolishing the tip and base portions of the strand coil 71, the surface of the coil wires dissolves and the outer diameter of the strand coil 71 decreases. As a result, gaps are formed between adjacent coil wires in the strand coil 71, and the loosely wound tip portion 72 and the loosely wound base portion 73 can be provided. In addition, the flexibility of the strand coil 71 is improved due to the reduction in the outer diameter of the coil wires, so the snare 10 has improved passability within the blood vessel. In addition, electrolytic polishing improves the wettability of the material forming the fixing portion 80 of the strand coil 71, thereby improving the fixing strength between the strand coil 71 and the fixing portion 80.

[0038] The outer and inner diameters of the strand coil 71 are determined in accordance with the outer diameter of the core wire 20. The outer diameter is, for example, 0.3 mm to 1.0 mm, with 0.35 mm as an example. The inner diameter is, for example, 0.25 mm to 0.8 mm, with 0.28 mm as an example. The outer diameter of the individual wires forming the strand coil 71 is, for example, 0.02 mm to 0.05 mm, with 0.035 mm as an example. The number of individual wires forming the strand coil 71 is, for example, 4 to 12, with 6 as an example. The length of the strand coil 71 in the longitudinal direction is, for example, 10 mm to 250 mm, with 200 mm as an example.

[0039] The cylindrical member 70 is formed from a metal material such as stainless steel. If the cylindrical member 70 is made of a resin material, it may twist and wrinkle when rotational force is applied, which can increase sliding resistance when passing through the vessel or sheath 90. In contrast, if the cylindrical member 70 is made of a metal material, it has high strength and is less prone to deformation. Furthermore, it can suppress deformation of the snare wire 40 and snare coil 50 placed inside the lumen of the strand coil 71. As a result, the cylindrical member 70 can maintain high rotational force transmission while suppressing an increase in sliding resistance when passing through the vessel or sheath 90 of the snare 10.

[0040] The fixing portion 80 has a tip fixing portion 81, an intermediate fixing portion 82 located closer to the base than the tip fixing portion 81, and a base fixing portion 83 located closer to the base than the intermediate fixing portion 82. The fixing portion 80 is formed from brazing material or solder. The material used to form the fixing portion 80 is, for example, gold-tin solder or silver-tin solder. The fixing portion 80 effectively transmits the rotational force applied to the core wire 20 to the snare loop 30.

[0041] The tip fixing portion 81 fixes the tip of the strand coil 71, the tip of the core wire 20, the portion of the snare wire 40 that is further forward than the first wire end 41 and the second wire end 42 and further back than the bent portion 32, and the portion of the snare coil 50 that is further forward than the first coil end 51 and the second coil end 52 and further back than the bent portion 32, at the tip of the tip loosely wound portion 72 of the strand coil 71. The tip fixing portion 81 enters the lumen of the strand coil 71 through the gaps between adjacent coil wires in the tip loosely wound portion 72 of the strand coil 71, so that the tip of the core wire 20, the strand coil 71, the snare wire 40 and the snare coil 50 can be firmly fixed. A hemispherical portion 84 is formed at the tip of the tip fixing portion 81, which is located further forward than the strand coil 71 and the core wire 20. As a result, the snare 10 can suppress damage to blood vessels caused by the tip fixing portion 81. The hemispherical portion 84 also suppresses damage to blood vessels. The length of the tip fixing portion 81 in the longitudinal direction is, for example, 0.4 mm to 2.0 mm, and preferably 0.5 mm to 1.0 mm.

[0042] The intermediate fixing portion 82 fixes the portion between the tip and base of the strand coil 71 at the base end of the loosely wound tip portion 72 of the strand coil 71, the surface of the tapered portion 27 of the core wire 20, and the portion of the snare wire 40 that is tipward to the first wire end 41 and the second wire end 42, and baseward to the snare coil 50. The intermediate fixing portion 82 enters the lumen of the strand coil 71 through the gaps between adjacent coil wires in the loosely wound tip portion 72 of the strand coil 71, so that the surface of the tapered portion 72 of the core wire 20, the strand coil 71, and the snare wire 40 can be firmly fixed. The length in the longitudinal direction between the tip fixing portion 81 and the intermediate fixing portion 82 is, for example, 10 mm to 45 mm, and is 15 mm as an example.

[0043] The base end fixing portion 83 fixes the base end of the strand coil 71 to the surface of the second constant outer diameter portion 26 of the core wire 20. Since the base end fixing portion 83 enters the lumen of the strand coil 71 through the gaps between the coil wires in the loosely wound base end portion 73 of the strand coil 71, the strand coil 71 and the second constant outer diameter portion 26 can be firmly fixed.

[0044] The strand coil 71 is fixed to the core wire 20 at the tip fixing part 81 at the tip loosely wound tip section 72, at the base end of the tip loosely wound tip section 72 at the intermediate fixing part 82, and at the base end fixing part 83 at the base end loosely wound base section 73. In addition, the portion of the strand coil 71 adjacent to the base end of the tip loosely wound tip section 72 is tightly wound so that there are no gaps between the coil wires. As a result, the strand coil 71 can increase the fixing strength to the core wire 20 by the loosely wound tip loosely wound tip section 72 and base end loosely wound base section 73, while maintaining torque transmission performance due to the tightly wound portion of the coil wires. Therefore, the snare 10 can more effectively transmit the rotational force applied to the base end of the core wire 20 to the tip side.

[0045] Next, the method of using the snare drum 10 according to the first embodiment will be described.

[0046] The surgeon, with the loop portion 31 of the snare 10 housed in the sheath 90, brings the tip of the snare 10 to the vicinity of the object 200 to be captured inside the blood vessel. Next, as shown in Figure 2(A), the surgeon extends the loop portion 31 out of the sheath 90 and positions the object 200 inside the loop portion 31. In this state, as shown in Figure 2(B), the surgeon pulls the snare 10 towards the proximal end and / or pushes the sheath 90 towards the tip, housing the proximal end of the loop portion 31 into the sheath 90. This reduces the size of the loop portion 31, allowing the object 200 to be grasped by the loop portion 31 and the tip of the sheath 90. If the surgeon wants to rotate the object 200, they rotate the proximal end of the snare 10. The snare 10 according to the first embodiment has high rotational force transmission capabilities, so that the rotational force applied to the base end can be effectively transmitted to the loop portion 31, and the gripped object 200 can be rotated.

[0047] Next, we will explain how to coat the snare loop 30 with the tip coating layer 60. First, as shown in Figure 6(A), a flexible expander 300, such as a silicone balloon, is placed inside the snare loop 30 before the tip coating layer 60 is applied. Next, as shown in Figure 6(B), internal pressure is applied to the expander 300 to expand it and bring it into contact with the inside of the snare loop 30. At this time, the internal pressure is adjusted so that the expander 300 penetrates approximately 33% of the surface of the snare loop 30 in a cross-section perpendicular to the snare wire 40, thereby masking the inner surface of the snare loop 30. In this state, as shown in Figure 6(C), a solution 301 containing the material of the tip coating layer 60 is coated by dipping over the area from the snare loop 30 to the base end of the strand coil 71. Next, as shown in Figure 6(D), the internal pressure of the expander 300 is removed and it is taken out of the snare loop 30, and the solution 301 coated on the snare loop 30 is dried. This allows a tip coating layer 60 to be formed on the snare loop 30. For example, as shown in Figure 3, of the six strands of wire arranged circumferentially on the snare wire 40, the two inner strands (33.3% of the outer circumference) are not covered by the tip coating layer 60, while the four outer strands (66.6% of the outer circumference) are covered by the tip coating layer 60. Therefore, in a cross-section perpendicular to the long axis of the snare wire 40 forming the snare loop 30, it is preferable that the proportion of the outer circumference of the snare loop 30 occupied by the tip coating layer 60 exceeds 50% and is at most about 67%.

[0048] As described above, the snare 10 according to the first embodiment is a snare 10 for capturing or retrieving an object 200 inside a blood vessel, and comprises a core wire 20 extending in the longitudinal direction from the tip to the base, a snare loop 30 having a loop portion 31 formed of a flexible snare wire 40 on the tip side of the core wire 20, and a cylindrical member 70 arranged to cover the tip of the core wire 20 and the first wire end 41 and second wire end 42 of the snare wire 40, wherein the cylindrical member 70 is a strand coil 71 formed by twisting together two or more strands. The strand coil 31 has the flexibility and high torsional strength required for the snare 10, so that the rotational force applied to the base end of the core wire 20 can be effectively transmitted to the snare loop 30. Furthermore, compared to a coil made of a single strand, the strand coil 71 is less prone to deformation such as an increase in outer diameter due to loosening of the winding when the snare 10 is rotated, and can maintain its shape. This allows the snare 10 to suppress the increase in sliding resistance as it passes through the blood vessel or the sheath 90.

[0049] Furthermore, the tip of the core wire 20 includes a tapered section 27 in which the outer diameter increases from the tip to the base, and the snare wire 40 is fixed to the tapered section 27 of the core wire 20. This allows the rotational force applied to the base end of the core wire 20 to be effectively transmitted to the loop section 31 located at the tip.

[0050] Furthermore, the snare 10 is a snare 10 for capturing or retrieving an object 200 inside a blood vessel, and comprises a core wire 20 that extends elongated from tip to base and includes a tapered portion at the tip where the outer diameter increases from tip to base, a snare loop 30 having a loop portion 31 formed of a flexible snare wire 40 on the tip side of the core wire 20, and a cylindrical member 70 arranged to cover the tapered portion 27 of the core wire 20 and the first wire end 41 and second wire end 42 of the snare wire 40, wherein one of the first wire end 41 and the second wire end 42 is positioned closer to the base than the other. This allows the space between the strand coil 71 and the tapered portion 27, which gradually decreases toward the base, to be effectively filled by the first wire end 41 and the second wire end 42, which are positioned at different locations in the longitudinal direction. Therefore, the snare 10 has improved rotational force transmission because the reduction in diameter of the strand coil 71 due to the rotational force applied to the base end of the core wire 20 is suppressed.

[0051] Furthermore, the snare loop 30 includes a snare coil 50 that covers the outer circumference of the snare wire 40, and the strand coil 71 may cover the first coil end 51 and the second coil end 52 of the snare coil 50. This allows the snare 10 to increase the contact area between the snare loop 30 and the object 200, thereby improving the gripping force. In addition, the snare 10 can effectively transmit the rotational force applied to its base end to the snare loop 30 via the snare coil 50 covered by the strand coil 71.

[0052] Furthermore, the first wire end 41 may be located closer to the base end than the first coil end 51, and the second wire end 42 may be located closer to the base end than the second coil end 52. This allows the snare 10 to more effectively fill the space between the strand coil 71, which gradually decreases in size towards the base end, and the tapered portion 27 of the core wire 20. As a result, the snare 10 suppresses the reduction in diameter of the strand coil 71 due to the rotational force applied to the base end of the core wire 20, further improving the transmission of rotational force.

[0053] Furthermore, the snare wire 40 is formed from a stranded wire created by twisting together two or more strands, and the winding direction of the snare wire 40 coincides with the winding direction of the strand coil 71. As a result, the snare 10 has good interlocking between the strand coil 71 and the snare wire 40, and the transmission of rotational force is improved when rotating in the direction in which the winding of each strand of the strand coil 71 and the snare wire 40 tightens.

[0054] Furthermore, the snare 10 is a snare 10 for capturing or retrieving an object 200 inside a blood vessel, and comprises a core wire 20 that extends long from tip to base, and a snare loop 30 having a loop portion 31 formed of a flexible snare wire 40 on the tip side of the core wire 20, wherein the snare loop 30 has a tip coating layer 60 on the surface facing outward of the loop portion 31 that is more lubricated than the surface facing inward. As a result, the snare 10 can reduce sliding resistance when passing inside a blood vessel or when housing the loop portion 31 in the sheath 90. In addition, since the loop portion 31 has a portion on the surface facing inward that is less lubricated than the tip coating layer 60, the object 200 can be securely gripped by the loop portion 31 without slipping when gripping the object 200.

[0055] Furthermore, the tip coating layer 60 may be made of a hydrophilic polymer material. This improves the lubricity of the snare 10 when wet.

[0056] Furthermore, the snare wire 40 may be a stranded wire formed by twisting together two or more strands. This increases the flexibility of the snare wire 40 compared to the case where it is formed from a single strand, reduces sliding resistance when housing the loop portion 31 in the sheath 90, and allows for a more secure grip on the object 200 without it slipping due to the anchoring effect of the uneven surface of the stranded wire.

[0057] Furthermore, the snare loop 30 includes a snare coil 50 that covers the outer circumference of the snare wire 40, and the tip covering layer 60 may be provided on the surface of the snare coil 50. As a result, the snare loop 30 has irregularities formed on its surface by the snare coil 50. Therefore, the contact area between the snare 10 and the inner surface of the sheath 90 is reduced, and the sliding resistance when housing the loop portion 31 in the sheath 90 can be further reduced.

[0058] Furthermore, the snare coil 50 may be wound so that there are gaps between adjacent coil strands. This allows the tip coating layer 60 to fill the gaps between the coil strands of the snare coil 50, thereby suppressing the peeling of the tip coating layer 60 when the loop portion 31 is housed in the sheath 90.

[0059] <Second Embodiment> The snare 100 according to the second embodiment of the present invention differs from the first embodiment in that the snare loop 110 does not include an X-ray opaque snare coil.

[0060] In the second embodiment, the snare loop 110 is formed from a snare wire 111 that is flexible and radiopaque, as shown in Figures 7-8, and has a tip coating layer 60 on the surface of the snare wire 111. That is, in the second embodiment, the snare wire 111 provides the snare loop 110 with radiopaqueness. Since the snare loop 110 does not include a snare coil, its outer diameter can be reduced.

[0061] The snare wire 111 is a stranded wire formed by twisting together multiple strands, and a portion of the strands is made of an X-ray opaque material. In the second embodiment, the snare wire 111 is a stranded wire consisting of three first strands 112 made of an X-ray transparent material (e.g., stainless steel) and four second strands 113 made of an X-ray opaque material. The number of strands in the first strands 112 and second strands 113 is not limited.

[0062] The second wire 113 is formed from an X-ray opaque material such as Pt, Pt-Ni alloy, or Pt-Ir alloy. Pt, Pt-Ni alloy, and Pt-Ir alloy have high visibility under X-ray fluoroscopy, high workability, and excellent wettability with the material forming the fixing part 80, thus increasing the bonding strength.

[0063] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art within the technical framework of the present invention. For example, the snare loops 30 and 110 do not need to have a tip coating layer 60. Also, the angle of the loop portion 31 with respect to the long axis of the core wire 20 at the bent portion 32 of the snare loops 30 and 110 does not need to be 90 degrees. [Explanation of symbols]

[0064] 10, 100 Snare 20 core wires 27 Tapered section 30, 110 snare loops 31 Loop section 40, 111 snare wires 41 First wire end 42 Second wire end 50 Snare Coils 51 First coil terminal 52 Second coil terminal 60 Tip coating layer 70 Cylindrical member 71 strand coil 72 Tip loosely wound section 73 Base end sparsely wound part 80 Fixed part 81 Tip fixing part 82 Intermediate fixing part 83 Proximal fixation part 84 Hemisphere 200 Objects

Claims

1. A snare for capturing or retrieving objects within blood vessels, A core wire extending in the longitudinal direction from the tip to the base, A snare loop having a loop portion formed of a flexible snare wire at the tip end of the core wire, The system comprises a cylindrical member positioned to cover the tip of the core wire and the first and second wire ends of the snare wire, The snare drum is characterized in that the cylindrical member is a strand coil formed by twisting together two or more strands of wire.

2. The tip of the core wire includes a tapered portion in which the outer diameter increases from the tip to the base end. The snare according to claim 1, characterized in that the snare wire is fixed to the tapered portion of the core wire.

3. The snare according to claim 2, characterized in that one of the first wire end and the second wire end is positioned closer to the base end than the other.

4. The snare loop comprises a snare coil that covers the outer circumference of the snare wire, The snare according to claim 1 or 2, characterized in that the strand coil covers the first coil end and the second coil end of the snare coil.

5. The snare according to claim 4, characterized in that the first wire end is located closer to the base end than the first coil end, and the second wire end is located closer to the base end than the second coil end.

6. The snare wire is formed from a stranded wire made by twisting together two or more strands of wire. The snare according to claim 1 or 2, characterized in that the winding direction of the snare wire coincides with the winding direction of the strand coil.

7. The snare according to claim 1 or 2, characterized in that the snare loop has a tip coating layer on the surface facing outward of the loop portion that has higher lubricity than the surface facing inward.

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