Medical device

Abstract

Provided is a medical device that comprises a cutting part rotatable by a drive shaft and achieves improved operability.　A medical device (10) for removing an object in a living body lumen comprises: a rotary shaft (11) having a hollow drive shaft (20) that is rotatable and a hollow cutting part (80) that is rotationally driven by the drive shaft (20); a guide wire protection tube (40) disposed inside the drive shaft (20) and the cutting part (80); and a handle (90) rotatably housing a base end part of the rotary shaft (11). The guide wire protection tube (40) has: a small diameter part (45) that forms the tip end of the guide wire protection tube (40) and at least a portion of which is disposed inside the cutting part (80); and a body tube (42) that is located closer to the base end side than the small diameter part (45) and at least a portion of which is disposed inside the drive shaft (20). The inner diameter (D1) of the small diameter part (45) is smaller than the inner diameter (D2) of the body tube (42).

Description

medical devices

[0001] The present invention relates to a medical device for removing objects from a biological lumen.

[0002] Methods for treating stenoses caused by intravascular plaque or thrombus include expanding the blood vessel with a balloon and placing a mesh or coil stent in the blood vessel to support the blood vessel. However, these methods are difficult to use to treat stenoses that have hardened due to calcification or that occur at a branching point of the blood vessel. As a device that can treat such cases, an atherectomy device has been proposed that cuts the lesion and removes the cut material by suction (see, for example, Patent Document 1).

[0003] An atherectomy device has a cutting part that rotates at high speed at the tip of the device and a drive shaft that rotates the cutting part. When using an atherectomy device, a guidewire must be passed through the cutting part and drive shaft, which rotate at high speed, and the guidewire may be damaged by friction with the inner surface of the cutting part. For this reason, Patent Document 1 proposes a structure in which a flexible protective tube through which the guidewire can pass is placed inside the cutting part and drive shaft to protect the guidewire.

[0004] US Patent Application Publication No. 2021 / 0275210

[0005] The protective tube is positioned to penetrate the cutting portion and reach the tip of the atherectomy device. Therefore, a protective tube that protrudes distally beyond the cutting portion may reduce the ease of passage of the atherectomy device through the cutting target. To improve the ease of passage of the atherectomy device, the protective tube can be made thinner. However, making the protective tube thinner increases friction between the inner surface of the protective tube and the outer surface of the guidewire, reducing the operability of the atherectomy device.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a medical device having a cutting portion that can be rotated by a drive shaft, which can improve operability.

[0007] The above object is achieved by the invention described in (1) below. (1) A medical device according to the present invention is a medical device for removing an object from a biological lumen, comprising: a rotating shaft including a rotatable hollow drive shaft and a hollow cutting portion that is rotationally driven by the drive shaft; a guidewire protection tube disposed inside the rotating shaft; and a handle that rotatably houses a proximal end of the rotating shaft, wherein the guidewire protection tube comprises a small diameter portion that forms the distal end of the guidewire protection tube and at least a portion of which is disposed inside the cutting portion, and a main tube that is located proximal to the small diameter portion and at least a portion of which is disposed inside the drive shaft, and wherein the inner diameter of the small diameter portion is smaller than the inner diameter of the main tube.

[0008] In the medical device described in (1) above, the inner diameter of the main tube is larger than the inner diameter of the small diameter portion, which reduces contact resistance between the inner surface of the guidewire protection tube and the outer surface of the guidewire, thereby improving the operability of the guidewire passing through the inside of the guidewire protection tube.

[0009] (2) In the medical device described in (1) above, the outer diameter of the small diameter portion may be smaller than the outer diameter of the main tube, thereby improving the passability of the distal end portion of the medical device through a stricture.

[0010] (3) In the medical device according to (1) or (2), the material forming the small diameter portion may have higher abrasion resistance than the material forming the main tube, thereby suppressing abrasion of the small diameter portion, which has a small inner diameter and is therefore likely to come into contact with a guidewire, and suppressing the inflow of abrasion debris into the body.

[0011] (4) In the medical device described in any one of (1) to (3) above, the cutting section may include a first housing section having an inner diameter large enough to accommodate at least a portion of the small-diameter section, a second housing section located proximal to the first housing section and having an inner diameter larger than the inner diameter of the first housing section, and a first step section located between the first housing section and the second housing section and including a first step surface facing proximally, and the guidewire protection tube may include a first abutment surface facing distally and proximal to the small-diameter section, the outer diameter of the small-diameter section being smaller than the inner diameter of the first housing section, and the maximum outer diameter of the first abutment surface being larger than the inner diameter of the first housing section. This allows the first abutment surface of the guidewire protection tube to abut against the first step surface of the cutting section when the guidewire protection tube moves distally more than necessary. This prevents the medical device from preventing the distal end of the guidewire protection tube from protruding more than necessary from the distal end of the cutting section. If the tip of the guidewire protection tube protrudes more than necessary from the tip of the cutting part, the cutting part may not be able to contact the narrowed part, making it difficult to cut the narrowed part.However, because it does not protrude more than necessary, the cutting part can effectively cut the narrowed part.

[0012] (5) In the medical device described in (4) above, the rotating shaft may have a third housing portion located proximal to the second housing portion and having an inner diameter smaller than the inner diameter of the second housing portion, and the guidewire protection tube may have a second abutment surface facing proximally toward the base end and proximal to the first abutment surface, the second abutment surface having a maximum outer diameter larger than the inner diameter of the third housing portion. This allows the second abutment surface of the guidewire protection tube to abut against the distal surface of the third housing portion of the rotating shaft when the guidewire protection tube moves proximally beyond the tip of the cutting portion, thereby preventing the guidewire passing through the guidewire protection tube from coming into contact with the cutting portion.

[0013] (6) In the medical device according to any one of (1) to (5), the member including the small diameter portion and the member including the main tube may be separate members, thereby making it possible to easily form the member including the small diameter portion into a desired shape.

[0014] (7) In the medical device described in (5) above, the axial length between the first and second abutment surfaces of the guidewire protection tube may be shorter than the axial length between the first and second step surfaces of the rotating shaft. This allows the guidewire protection tube to move axially within a predetermined range inside the rotating shaft. This prevents the guidewire protection tube from being pushed axially inside the rotating shaft and hindering rotation of the rotating shaft.

[0015] (8) In the medical device described in (4) or (5) above, the guidewire protection tube may be fixed to a tube fixing portion of the handle, and the length of the guidewire protection tube from the tube fixing portion to the first abutment surface along the axis of the guidewire protection tube may be longer than the length from the tube fixing portion to the first step surface along the axis of the rotating shaft. As a result, when the rotating shaft is straight, the first abutment surface of the guidewire protection tube abuts against the first step surface of the rotating shaft, causing the guidewire protection tube to bend inside the rotating shaft. When the rotating shaft is bent after the medical device is inserted into the body, the amount of axial extension of the guidewire protection tube, which has a smaller diameter than the rotating shaft, is shorter than the amount of axial extension of the rotating shaft. In other words, when a tubular body is generally bent, the amount of axial compression on the side located inside the bend and subjected to a compressive force is smaller than the amount of axial extension on the side located outside the bend and subjected to a tensile force, resulting in overall extension of the tubular body. The larger the diameter of the tubular body, the greater the total amount of extension of the tubular body. Therefore, when the medical device is inserted into a tortuous lumen, the first abutment surface of the guidewire protection tube, which is located inside the rotating shaft and therefore has a smaller diameter than the rotating shaft and is less likely to stretch, can be positioned appropriately away from the first step surface. Therefore, when the medical device is actually used inside the tortuous lumen, the guidewire protection tube can be prevented from being stretched in the axial direction inside the rotating shaft and hindering the rotation of the rotating shaft.

[0016] Fig. 1 is a plan view showing a medical device according to an embodiment; Fig. 2 is a cross-sectional view showing the distal end of the medical device; Fig. 3 is a view showing the proximal end of the medical device, with the casing in cross-section and the rest in plan view; Fig. 4 is a cross-sectional view showing the vicinity of the distal ends of the inner tube and outer tube of the medical device; Fig. 5 is a schematic plan view showing the state of a guidewire protection tube inside the medical device; Fig. 6 is a schematic view showing the state in which a lesion is being removed by the medical device;

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the size and proportions of the components in the drawings may be exaggerated for the sake of explanation and may differ from the actual size and proportions. In this specification, the side of a medical device that is inserted into the body will be referred to as the "distal side," and the side that is operated will be referred to as the "proximal side."

[0018] The medical device 10 according to this embodiment is inserted into a blood vessel and used in treatment of acute lower limb ischemia or deep vein thrombosis to destroy and remove thrombi, plaque, atheroma, calcified lesions, etc. Note that the objects to be removed are not necessarily limited to thrombi, plaque, atheroma, and calcified lesions, and may be any object that may be present in a biological lumen.

[0019] As shown in Figures 1 to 3, the medical device 10 has a rotatable, long rotating shaft 11, a housing shaft 12 that rotatably houses the rotating shaft 11, a guidewire protection tube 40 that is disposed inside the rotating shaft 11, and a handle 90.

[0020] The rotating shaft 11 has a long drive shaft 20, a transport coil 30 for transporting an object, the drive shaft 20, a cutting section 80 for cutting an object such as a thrombus, and a connecting shaft 70 for connecting the drive shaft 20 to the cutting section 80.

[0021] The drive shaft 20 is a multi-layer coil in which coils are stacked in layers. The drive shaft 20 is flexible and has the property of being able to transmit drive torque acting from the base end side to the distal end side. The drive shaft 20 is rotatable inside the housing shaft 12. The drive shaft 20 includes an inner coil 21, an outer coil 22 surrounding the outside of the inner coil 21, and a distal protection tube 23 covering the outer peripheral surface of the distal portion of the outer coil 22. The drive shaft 20 may be a multi-layer coil with three or more layers. Alternatively, the drive shaft 20 may be a single-layer coil.

[0022] The connecting shaft 70 is rotatably supported by a distal end bearing portion 60 (described later) of the housing shaft 12. The proximal end of the connecting shaft 70 is connected to the distal end portion of the drive shaft 20, and the distal end of the connecting shaft 70 enters the interior of the cutting portion 80 and is connected to the cutting portion 80. The connecting shaft 70 has at least one groove-shaped passage 71 formed therein and extending along the axis. The passage 71 allows an object cut by the cutting portion 80 to pass through the inside of the distal end bearing portion 60 toward the proximal end. The guidewire protection tube 40 is disposed inside the connecting shaft 70 and passes through it. A third housing portion 73 is formed at the distal end of the connecting shaft 70, which enters the fitting portion 81 and is connected to the cutting portion 80. The distal end surface of the third housing portion 73 has a second stepped surface 72 facing the distal end.

[0023] 4, the conveying coil 30 is arranged so as to be wound around the outer periphery of the drive shaft 20. The tip of the conveying coil 30 is fixed to the outer periphery of the drive shaft 20. The conveying coil 30 is formed by loosely winding the wire that constitutes the conveying coil 30 so that there are gaps in the axial direction of the conveying coil 30.

[0024] The conveying coil 30 functions as an Archimedian screw (screw pump) when the drive shaft 20 rotates in the rated rotation direction, and conveys liquid or objects toward the base end. For this purpose, the conveying coil 30 is formed so that, when viewed from the base end, it is wound in the rated rotation direction as it moves toward the tip end. Note that the conveying coil 30 may also be formed so that, when viewed from the base end, it is wound in the opposite direction to the rated rotation direction as it moves toward the tip end. In this case, the conveying coil 30 functions as an Archimedian screw (screw pump) when the drive shaft 20 rotates in the rated rotation direction, and can convey liquid or objects toward the tip end. Note that the conveying coil 30 does not necessarily have to be provided.

[0025] Suitable materials for the drive shaft 20 and the conveying coil 30 include, for example, stainless steel, Ta, Ti, Pt, Au, W, polyolefins such as polyethylene and polypropylene, polyesters such as polyamide and polyethylene terephthalate, fluorine-based polymers such as ethylene-tetrafluoroethylene copolymer (ETFE), polyether ether ketone (PEEK), and polyimide.

[0026] 2 and 4, the tip protection tube 23 is a tubular body that covers the outer peripheral surface of the drive shaft 20 on the tip side of the conveying coil 30. The tip protection tube 23 is disposed inside a shaping portion 53 provided on the outer tubular shaft 50. The tip protection tube 23 is formed of a heat-shrinkable tube that shrinks in diameter when heated, for example, to fit tightly to the drive shaft 20. The tip protection tube 23 prevents damage caused by contact between the drive shaft 20 and the shaping portion 53 as the drive shaft 20 rotates.

[0027] The material of the heat shrinkable tube is not particularly limited, but may be, for example, polyolefin, nylon, Pebax, polyurethane, or polyethylene terephthalate.

[0028] The cutting unit 80 is a component that cuts and reduces objects such as thrombi, plaque, and calcified lesions. Therefore, "cutting" means applying force to an object in contact with it to reduce the size of the object. The method of applying force during cutting and the shape and form of the object after cutting are not limited. The cutting unit 80 has the strength to cut the above-mentioned objects. The cutting unit 80 is fixed to the outer peripheral surface of the tip of the connecting shaft 70. The cutting unit 80 has a large number of tiny abrasive grains on its surface. Alternatively, the cutting unit 80 may be equipped with a sharp blade.

[0029] The cutting portion 80 has a through hole that penetrates in the axial direction. The cutting portion 80 has a fitting portion 81 located on the base end side, a second housing portion 82 located further distal than the fitting portion 81, a first housing portion 83 located further distal than the second housing portion 82, and a first step portion 84 located between the second housing portion 82 and the first housing portion 83.

[0030] The engagement portion 81 is located at the base end of the cutting portion 80, and the tip end of the connecting shaft 70 fits into and engages with it. Therefore, the inner diameter of the engagement portion 81 is approximately the same as the outer diameter of the tip end of the connecting shaft 70. The second accommodating portion 82 is a portion formed continuously from the engagement portion 81 toward the tip end. The inner diameter of the second accommodating portion 82 matches the inner diameter of the engagement portion 81, but does not have to match.

[0031] The first step portion 84 has a first step surface 85 facing the base end direction. The first step surface 85 is located closer to the base end than the second step surface 72 of the connecting shaft 70 and is spaced apart from the second step surface 72. The second accommodating portion 82 is disposed between the first step surface 85 and the second step surface 72.

[0032] The first accommodating portion 83 is located closer to the tip side than the second accommodating portion 82 and has an inner diameter smaller than the inner diameter of the second accommodating portion 82. The first accommodating portion 83 forms an opening on the tip side of the cutting portion 80.

[0033] The constituent material of the cutting portion 80 preferably has a strength sufficient to cut a thrombus, and suitable materials for use include stainless steel, Ta, Ti, Pt, Au, W, shape memory alloys, and super steel alloys. The constituent material of the connecting shaft 70 preferably has a certain degree of strength, and the above-mentioned materials applicable to the cutting portion 80 can be used.

[0034] As shown in Figures 2 to 4, the guidewire protection tube 40 is a tubular body disposed inside the rotating shaft 11. The guidewire protection tube 40 is formed with a guidewire lumen 41 through which a guidewire passes. The guidewire protection tube 40 is formed with a structure independent of the rotating shaft 11 and does not rotate together with the rotating shaft 11. The guidewire protection tube 40 prevents the guidewire passing through the guidewire lumen 41 from rubbing against the drive shaft 20, which is the rotating shaft 11, the connecting shaft 70, and / or the cutting portion 80. The guidewire protection tube 40 has a main tube 42 that forms the majority of the guidewire protection tube 40, a tip member 43 fixed to the tip end of the main tube 42, and a proximal end covering tube 44 fixed to the main tube 42 so as to cover the proximal end of the main tube 42.

[0035] The main tube 42 is a tubular body that can be flexibly bent along its axis. The main tube 42 is a braided tube in which a reinforcing member 42B is sandwiched between resin layers to provide flexibility and strength. The main tube 42 includes an inner layer 42A that forms the inner surface, an outer layer 42C that forms the outer surface, and a reinforcing member 42B located between the inner layer 42A and the outer layer 42C. The outer diameter of the main tube 42 is smaller than the inner diameter of the connecting shaft 70 and the inner diameter of the drive shaft 20.

[0036] The constituent material of the outer layer 42C is not particularly limited, but may be, for example, polyimide. The constituent material of the inner layer 42A is not particularly limited, but may be, for example, a mixed material of polytetrafluoroethylene (PTFE) and polyimide. The inner layer 42A and the outer layer 42C may be integrally formed from the same material.

[0037] The reinforcing member 42B is used to reinforce the main tube 42 and is formed by braiding multiple wires into a tubular shape using a braider. The material of the outer layer 42C or the inner layer 42A fills the gaps between the multiple wires in the reinforcing member 42B. Note that the reinforcing member 42B does not necessarily have to be provided. The material of the reinforcing member 42B is not particularly limited, but may be, for example, a metal such as stainless steel or a resin.

[0038] The tip member 43 has a small diameter portion 45 located at the tip end of the tip member 43, a large diameter portion 46 located at the base end of the tip member 43, and a transition portion 47 located between the small diameter portion 45 and the large diameter portion 46.

[0039] The small diameter portion 45 is rotatably accommodated in the first accommodating portion 83 of the cutting portion 80. The outer diameter D3 of the small diameter portion 45 is smaller than the inner diameter D9 of the first accommodating portion 83. This allows the small diameter portion 45 to rotate inside the first accommodating portion 83. The outer diameter D3 of the small diameter portion 45 is smaller than the inner diameter D9 of the first accommodating portion 83. This allows the small diameter portion 45 to rotate inside the first accommodating portion 83. The outer diameter D3 of the small diameter portion 45 is also smaller than the outer diameter D4 of the main tube 42. This improves the insertability of the small diameter portion 45, which protrudes distally beyond the cutting portion 80, into the narrowed portion. The outer diameter D3 of the small diameter portion 45 may be equal to or larger than the outer diameter D4 of the main tube 42. The inner diameter D1 of the small diameter portion 45 is smaller than the inner diameter D2 of the main tube 42. This narrows the area (small diameter portion 45) where the inner diameter of the guidewire protection tube 40 is small and frictional resistance with the guidewire is large, thereby improving the operability of the medical device 10 and the guidewire.

[0040] The axial length L2 of the small diameter portion 45 is longer than the axial length L4 of the first accommodating portion 83. This allows the tip of the small diameter portion 45 to be positioned more distal than the tip of the first accommodating portion 83, i.e., the tip of the cutting portion 80, even if the guidewire protection tube 40 moves axially inside the rotating shaft 11. As a result, the guidewire accommodated in the guidewire protection tube 40 can be prevented from rubbing against the rotating cutting portion 80.

[0041] The large diameter portion 46 is rotatably housed in the second housing portion 82 of the cutting portion 80. The outer diameter D5 of the large diameter portion 46 is larger than the outer diameter D3 of the small diameter portion 45 and larger than the outer diameter D4 of the main tube 42. The large diameter portion 46 has a second abutment surface 48 facing the proximal end direction on its proximal end surface. The outer diameter D5 of the large diameter portion 46 is smaller than the inner diameter D8 of the second housing portion 82. This allows the large diameter portion 46 to rotate inside the second housing portion 82. The inner diameter D5 of the large diameter portion 46 approximately matches the outer diameter D4 of the main tube 42 that fits into the large diameter portion 46.

[0042] The transition portion 47 is located between the small diameter portion 45 and the large diameter portion 46. The inner diameter of the transition portion 47 is the same as the inner diameter D1 of the small diameter portion 45. Note that the inner diameter of the transition portion 47 does not have to be the same as the inner diameter D1 of the small diameter portion 45, and may, for example, taper downward toward the distal end. The outer diameter of the base end of the transition portion 47 is the same as the outer diameter D5 of the large diameter portion 46. Furthermore, the transition portion 47 has a first abutment surface 49 on its outer peripheral surface that faces the distal end. The minimum outer diameter of the first abutment surface 49 is the same as the outer diameter D3 of the small diameter portion 45, and the maximum outer diameter of the first abutment surface 49 is the same as the outer diameter D5 of the large diameter portion 46. The axial length L1 between the first abutment surface 49 and the second abutment surface 48 is shorter than the axial length L3 between the first step surface 85 and the second step surface 72. This allows the tip member 43 to move within a predetermined range (within the range of L3-L1) in the axial direction inside the cutting portion 80.

[0043] The maximum outer diameter of the first abutment surface 49 is larger than the inner diameter D9 of the first accommodating portion 83. As a result, the first abutment surface 49 moving toward the distal end cannot pass through the inside of the first accommodating portion 83 and hits the first step surface 85.

[0044] The maximum outer diameter of the second abutment surface 48 is larger than the inner diameter D7 of the tip portion of the connecting shaft 70. As a result, the second abutment surface 48 moving toward the base end cannot pass through the inside of the connecting shaft 70 and hits the second step surface 72.

[0045] When the guidewire protection tube 40 moves proximally and the second abutment surface 48 abuts against the second stepped surface 72, the distal end of the small diameter portion 45 (the distal end of the guidewire protection tube 40) is located distally of the distal end of the first accommodating portion 83 (the distal end of the cutting portion 80). That is, the axial length L5 from the second abutment surface 48 to the distal end of the small diameter portion 45 is longer than the axial length L6 from the second stepped surface 72 to the distal end of the first accommodating portion 83. This prevents the guidewire inserted into the guidewire protection tube 40 from rubbing against the cutting portion 80, even when the guidewire protection tube 40 moves proximally to the greatest extent possible inside the rotating shaft 11 and the second abutment surface 48 abuts against the second stepped surface 72.

[0046] The tip member 43 is formed from a material with higher abrasion resistance than the main tube 42. The abrasion resistance can be evaluated by comparing the abrasion rate, specific abrasion amount, or friction coefficient in an abrasion test under the same conditions. The tip member 43 is less likely to bend (has higher bending rigidity) and deform than the main tube 42. The tip member 43 is made of a material such as engineering plastic, ceramic, or metal. The engineering plastic may be a super engineering plastic. Examples of engineering plastics (super engineering plastics) include polyetheretherketone (PEEK), polyimide, polyetherimide, and polytetrafluoroethylene (PTFE).

[0047] The proximal end covering tube 44 is a tubular body fixed to the outer peripheral surface of the proximal end of the main tube 42 in order to reinforce the proximal end of the main tube 42. The proximal end covering tube 44 is a heat-shrinkable tube made of, for example, polyethylene terephthalate. The proximal end covering tube 44 is fixed to a tube fixing portion 98 formed on the casing 92 of the handle 90. The tube fixing portion 98 is formed of, for example, an adhesive. This prevents the guidewire protection tube 40 from rotating along with the outer rotating shaft 11.

[0048] The length along the axis from the tube fixing portion 98 to the first abutment surface 49 of the guidewire protection tube 40 (the axial length from the tube fixing portion 98 to the first abutment surface 49 when the guidewire protection tube 40 is straight and not curved) is longer than the length along the axis from the tube fixing portion 98 to the first step surface 85 of the rotating shaft 11 (the axial length from the tube fixing portion 98 to the first step surface 85 when the rotating shaft 11 is straight and not curved). Therefore, as shown in FIG. 5 , when the rotating shaft 11 is straight, the first abutment surface 49 of the guidewire protection tube 40 abuts against the first step surface 85 of the rotating shaft 11, and the guidewire protection tube 40 bends inside the rotating shaft 11. When the rotating shaft 11 is bent, the axial extension of the guidewire protection tube 40, which has a smaller diameter than the rotating shaft 11, is shorter than the axial extension of the rotating shaft 11. That is, when a tubular body is generally bent, the amount of axial compression on the side located on the inside of the bend and subjected to a compressive force is smaller than the amount of axial expansion on the side located on the outside of the bend and subjected to a tensile force, resulting in expansion of the tubular body as a whole. The larger the diameter of the tubular body, the greater the total expansion of the tubular body. Therefore, when the medical device 10 is inserted into a tortuous lumen, the first abutment surface 49 of the guidewire protection tube 40, which is located inside the rotating shaft 11 and therefore has a smaller diameter than the rotating shaft 11 and is therefore less likely to expand, can be positioned appropriately away from the first step surface 85. Therefore, when the medical device 10 is actually used in a tortuous lumen, the guidewire protection tube 40 is prevented from being axially stretched inside the rotating shaft 11, thereby preventing the rotation of the rotating shaft 11 from being hindered.

[0049] As shown in FIGS. 1 to 4, the housing shaft 12 has an outer tube shaft 50 that rotatably houses the rotary shaft 11, and a tip bearing portion 60 that rotatably supports the rotary shaft 11.

[0050] The outer tubular shaft 50 includes an outer tube 51, an inner tube 52, a shaping portion 53, a first covering tube 54 that is in close contact with the outer peripheral surface of the outer tube 51, and a second covering tube 55 that is in close contact with the outer peripheral surface of the shaping portion 53. The outer tubular shaft 50 is a long tubular body that houses the drive shaft 20. The outer tubular shaft 50 can transmit torque applied by the surgeon using a rotation operation portion 91 fixed to the proximal end of the outer tubular shaft 50 to the distal end. A first lumen 57 is formed between the outer tube 51 and the inner tube 52 for delivering a liquid such as physiological saline to the distal end. At least one side hole 58 that penetrates from the inner peripheral surface to the outer peripheral surface is formed at the distal end of the outer tubular shaft 51. By rotating the outer tubular shaft 50, the cutting portion 80 can be directed toward the lesion.

[0051] The outer tube 51 preferably has flexibility so as to bend within a biological lumen and high torque transmission capability. The outer tube 51 can be made of, for example, a circular tube made of a metal or resin material having a certain degree of strength, with a spiral slit or groove formed by laser processing. The material of the outer tube 51 is not particularly limited, and suitable materials include metals such as stainless steel, nitinol (NiTi), Ta, Ti, Pt, Au, and W, and engineering plastics such as ABS resin, polycarbonate (PC), polymethyl methacrylate (PMMA), polyacetal (POM), polyphenylsulfone (PPSU), polyethylene (PE), carbon fiber, and polyether ether ketone (PEEK).

[0052] The first covering tube 54 is a tubular body that fits tightly against the outer peripheral surface of the outer tube 51. The first covering tube 54 prevents the liquid in the first lumen 57 from leaking through a gap in a spiral slit formed in the outer tube 51. The first covering tube 54 is formed of a heat-shrinkable tube that shrinks in diameter when heated, for example, to fit tightly against the outer tube 51.

[0053] The inner tube 52 is disposed inside the outer tube 51 with a gap therebetween. The gap between the inner tube 52 and the outer tube 51 is a first lumen 57. A second lumen 59 is formed inside the inner tube 52 for discharging objects such as the excised thrombus in the proximal direction. The distal end of the inner tube 52 is fixed to the inner circumferential surface of the shaping portion 53 with an adhesive or the like. The proximal end of the inner tube 52 is located inside the handle 90.

[0054] The material of the inner tube 52 desirably has a certain degree of flexibility and low friction, and suitable materials include polyetheretherketone (PEEK), fluoropolymers such as PTFE and ETFE, polymethyl methacrylate (PMMA), polyethylene (PE), polyether block acid copolymer (PEBAX), nylon, PEBAX, polyimide, styrene-ethylene-butylene-styrene (SEBS), and combinations thereof. The inner tube 52 may have braided reinforcing wires.

[0055] The shaping portion 53 is located at the distal end of the outer tubular shaft 50. The shaping portion 53 is bent at two bent portions 56 so that the axial center of the proximal end of the shaping portion 53 is misaligned with the axial center of the distal end. The number of bent portions 56 may be one, or three or more. By rotating the outer tubular shaft 50, the shaping portion 53 can direct the cutting portion 80 toward the lesion and further press the cutting portion 80 firmly against the lesion. The shaping portion 53 can be made of a material that is applicable to the outer tube 51 described above, for example.

[0056] The second covering tube 55 is a tubular body that fits tightly against the outer circumferential surface of the shaping portion 53. The second covering tube 55 is formed of a heat-shrinkable tube that shrinks in diameter when heated, for example, so that it fits tightly against the shaping portion 53.

[0057] As shown in Figure 2, the tip bearing 60 is fixed to the tip of the shaping part 53 and is disposed further distally than the shaping part 53. The tip bearing 60 rotatably supports the connecting shaft 70 of the rotary shaft 11. A tip opening 61 is formed at the tip side of the tip bearing 60, which transports and takes in the cut object such as a thrombus, blood, and liquid released from the side hole 58 into the second lumen 59. The tip of the tip bearing 60 is located proximal to the cutting part 80. It is preferable that the material constituting the tip bearing 60 has a certain degree of strength, and the materials applicable to the cutting part 80 described above can be used.

[0058] As shown in FIGS. 1 and 3, the handle 90 includes a rotation operation unit 91, a casing 92, a drive unit 93, a liquid delivery unit 94, a discharge port 95, a liquid delivery port 96, and an operation switch 97.

[0059] The casing 92 has a rotary operation unit 91 rotatably connected to its tip, and houses a drive unit 93 and a liquid delivery unit 94 inside. The casing 92 also houses the base end of the outer tubular shaft 50 inside.

[0060] The rotation operation unit 91 is a part that is operated by the surgeon's fingers to apply torque to the outer tubular shaft 50. The rotation operation unit 91 is rotatably connected to the tip end of the casing 92. The rotation operation unit 91 is fixed to the outer peripheral surface of the base end of the outer tubular shaft 50.

[0061] The drive unit 93 is, for example, a hollow motor. The drive unit 93 rotates using a battery (not shown) or externally supplied power. The drive shaft 20 is fixed to a hollow drive rotor of the hollow motor. The rotation speed of the drive unit 93 is not particularly limited, but is, for example, 10,000 to 150,000 rpm, and preferably 20,000 to 120,000 rpm. The configuration of the drive unit 93 is not particularly limited. Since the drive unit 93 is a hollow motor, the guidewire protection tube 40 and the guidewire can pass through the drive unit 93.

[0062] The discharge port 95 is a tube that discharges liquid or objects to the outside of the casing 92. The discharge port 95 is connected to, for example, a waste liquid bag 100 that can store liquid or objects. Note that the discharge port 95 may be connected to a suction source that can actively suck, such as a pump or a syringe.

[0063] The fluid supply unit 94 is a pump that supplies fluid to the first lumen 57. The fluid supply unit 94 is connected to a fluid supply port 96 that receives a supply of fluid such as physiological saline from a fluid supply source 110 external to the casing 92, and can suck the fluid from the fluid supply port 96 and discharge it into the first lumen 57. The external fluid supply source 110 is, for example, a physiological saline bag, but is not limited to this. The fluid supply unit 94 may be provided externally rather than on the handle 90.

[0064] The operation switch 97 is a part that the surgeon operates to drive and stop the drive unit 93. The operation switch 97 is located on the outer surface of the casing 92.

[0065] Next, a method of using the medical device 10 according to the embodiment will be described. Here, as shown in Fig. 6, a case where a calcified lesion S in a blood vessel is destroyed and transported will be described as an example.

[0066] First, the surgeon inserts the guidewire W into the blood vessel and reaches the vicinity of the lesion S. Next, the surgeon inserts the proximal end of the guidewire W into the guidewire lumen 41 of the medical device 10. Thereafter, the surgeon moves the cutting portion 80 of the medical device 10 to the vicinity of the lesion S using the guidewire W as a guide.

[0067] Next, the surgeon operates the operation switch 97 to start the operation of the drive unit 93 and the fluid delivery unit 94. This causes the drive shaft 20 connected to the drive unit 93, and the connecting shaft 70 and cutting unit 80 connected to the drive shaft 20 to rotate. As a result, the surgeon can cut the lesion S using the cutting unit 80. Furthermore, when the drive shaft 20 rotates, as shown in FIG. 4, the delivery coil 30 fixed to the drive shaft 20 generates a force that delivers the liquid or object in the second lumen 59 toward the proximal end. As a result, as shown in FIG. 2, a suction force acts on the distal opening 61 of the second lumen 59 of the outer tube shaft 50.

[0068] When the surgeon wishes to change the position of the cutting unit 80 in the circumferential direction, he or she can operate the rotation operation unit 91 shown in FIGS. 1 and 3 . When the surgeon rotates the rotation operation unit 91, the outer tube shaft 50, which is fixed to the rotation operation unit 91, rotates. Rotating the outer tube shaft 50 changes the position and direction of the distal portion of the outer tube shaft 50 beyond the bent portion 56, as shown in FIG. 6 , thereby changing the position and direction of the cutting unit 80. Therefore, by simply operating the rotation operation unit 91, cutting can be performed while changing the position and direction of the cutting unit 80, without having to rotate the entire handle 90, which is difficult to rotate significantly. Furthermore, the surgeon moves the entire handle 90 or the outer tube shaft 50 exposed outside the body, reciprocating the outer tube shaft 50 along the longitudinal direction of the blood vessel. This allows the cutting unit 80 to cut the lesion S along the longitudinal direction of the blood vessel.

[0069] 1 to 4, when the operation of the fluid delivery unit 94 is started, physiological saline solution is sucked into the fluid delivery unit 94 from the fluid delivery port 96 and discharged into the first lumen 57. The physiological saline solution discharged into the first lumen 57 moves toward the distal end and is released into the blood vessel from the side hole 58 formed at the distal end of the outer tube 51.

[0070] A portion of the saline solution released into the blood vessel, together with the blood and the cut object, is sucked into the second lumen 59 from the distal opening 61 of the outer tubular shaft 50. The object that has entered the second lumen 59 moves in the proximal direction through the second lumen 59. The object that has entered the second lumen 59 is transported in the proximal direction by the transport coil 30 and is discharged into the external waste fluid bag 100 via the discharge port 95 of the handle 90.

[0071] The guidewire protection tube 40 is fixed to the handle 90 by the tube fixing portion 98 and therefore does not rotate together with the rotating shaft 11. Therefore, the guidewire protection tube 40 can suppress the guidewire W from rubbing against the cutting portion 80 and generating wear powder.

[0072] After the cutting and transportation of the lesion S is completed, the surgeon operates the operation switch 97. This stops the rotation of the drive shaft 20 and stops the delivery of fluid by the fluid delivery unit 94. The surgeon then removes the medical device 10 from the blood vessel, completing the treatment.

[0073] As described above, the medical device 10 according to this embodiment is a medical device 10 for removing an object within a biological lumen, and includes: a rotating shaft 11 including a rotatable hollow drive shaft 20 and a hollow cutting portion 80 that is rotationally driven by the drive shaft 20; a guidewire protection tube 40 disposed inside the rotating shaft 11; and a handle 90 that rotatably houses the proximal end of the rotating shaft 11. The guidewire protection tube 40 includes a small-diameter portion 45 that forms the distal end of the guidewire protection tube 40 and is at least partially disposed inside the cutting portion 80; and a main tube 42 that is located proximal to the small-diameter portion 45 and is at least partially disposed inside the drive shaft 20, the inner diameter D1 of the small-diameter portion 45 being smaller than the inner diameter D2 of the main tube 42. In this medical device 10, the inner diameter D2 of the main tube 42 is larger than the inner diameter D1 of the small-diameter portion 45, thereby reducing contact resistance between the inner surface of the guidewire protection tube 40 and the outer surface of the guidewire W. Therefore, the medical device 10 can improve the operability of the guidewire W passing through the inside of the guidewire protection tube 40.

[0074] The outer diameter D3 of the small diameter portion 45 is smaller than the outer diameter D4 of the main tube 42. This allows the medical device 10 to improve the passability of the distal end portion through a stricture.

[0075] The material forming the small diameter portion 45 has higher abrasion resistance than the material forming the main tube 42. This allows the medical device 10 to suppress abrasion of the small diameter portion 45, which has a small inner diameter and is therefore likely to come into contact with the guidewire W, and to suppress the inflow of abrasion debris into the body.

[0076] The cutting portion 80 has a first accommodating portion 83 having an inner diameter D9 capable of accommodating at least a portion of the small diameter portion 45, a second accommodating portion 82 located proximally of the first accommodating portion 83 and having an inner diameter D8 larger than the inner diameter D9 of the first accommodating portion 83, and a first step portion 84 located between the first accommodating portion 83 and the second accommodating portion 82 and having a first step surface 85 facing proximally, and the guidewire protection tube 40 has a first abutting surface 49 facing distally and proximally of the small diameter portion 45, the outer diameter D3 of the small diameter portion 45 being smaller than the inner diameter D9 of the first accommodating portion 83, and the maximum outer diameter of the first abutting surface 49 being larger than the inner diameter D9 of the first accommodating portion 83. As a result, if the guidewire protection tube 40 moves distally more than necessary, the first abutting surface 49 of the guidewire protection tube 40 will abut against the first step surface 85 of the cutting portion 80. Therefore, the medical device 10 can prevent the tip of the guidewire protection tube 40 from protruding more than necessary from the tip of the cutting section 80. If the tip of the guidewire protection tube 40 protrudes more than necessary from the tip of the cutting section 80, the cutting section 80 may not be able to contact the narrowed section, making it difficult to cut the narrowed section, but because the tip of the guidewire protection tube 40 does not protrude more than necessary, the cutting section 80 can effectively cut the narrowed section.

[0077] The rotating shaft 11 has a third accommodating portion 73 that is located more proximal than the second accommodating portion 82 and has an inner diameter D7 smaller than the inner diameter D8 of the second accommodating portion 82, and the guidewire protection tube 40 has a second abutment surface 48 that is more proximal than the first abutment surface 49 and faces in the proximal direction, and the maximum outer diameter of the second abutment surface 48 is larger than the inner diameter D7 of the third accommodating portion 73. As a result, if the guidewire protection tube 40 moves more proximally than necessary, the second abutment surface 48 of the guidewire protection tube 40 will abut against the surface of the distal side of the third accommodating portion 73 of the rotating shaft 11. Therefore, the medical device 10 can prevent the distal end of the guidewire protection tube 40 from moving proximally beyond the distal end of the cutting portion 80, and can prevent the guidewire W passing through the guidewire protection tube 40 from contacting the cutting portion 80.

[0078] The member including the small diameter portion 45 and the member including the main tube 42 are separate bodies, which makes it possible to easily form the member including the small diameter portion 45 into a desired shape.

[0079] The axial length between the first abutment surface 49 and the second abutment surface 48 of the guidewire protection tube 40 is shorter than the axial length between the first step surface 85 and the second step surface 72 of the rotating shaft 11. This allows the guidewire protection tube 40 to move axially within a predetermined range inside the rotating shaft 11. This prevents the guidewire protection tube 40 from being pushed axially inside the rotating shaft 11, thereby preventing the rotation of the rotating shaft 11 from being hindered.

[0080] The guidewire protection tube 40 is fixed to a tube fixing portion 98 of the handle 90, and the length from the tube fixing portion 98 to the first abutment surface 49 along the axis of the guidewire protection tube 40 is longer than the length from the tube fixing portion 98 to the first step surface 85 along the axis of the rotating shaft 11. As a result, when the rotating shaft 11 is straight, the first abutment surface 49 of the guidewire protection tube 40 abuts against the first step surface 85 of the rotating shaft 11, and the guidewire protection tube 40 is curved inside the rotating shaft 11. Then, when the medical device 10 is inserted into the body and the rotating shaft 11 is bent, the amount of axial extension of the guidewire protection tube 40, which has a smaller diameter than the rotating shaft 11, is shorter than the amount of axial extension of the rotating shaft 11. In other words, when a tubular body is generally curved, the amount of axial compression on the side located inside the curve and where a compressive force acts is smaller than the amount of axial extension on the side located outside the curve and where a tensile force acts, and therefore the tubular body as a whole is stretched. The total amount of stretch of this tubular body increases as the diameter of the tubular body increases. Therefore, when the medical device 10 is inserted into a tortuous lumen, the first abutment surface 49 of the guidewire protection tube 40, which is located inside the rotating shaft 11 and therefore has a smaller diameter than the rotating shaft 11 and is therefore less likely to stretch, can be positioned appropriately away from the first step surface 85. Therefore, when the medical device 10 is actually used in a tortuous lumen, the guidewire protection tube 40 is prevented from being stretched in the axial direction inside the rotating shaft 11, which would hinder the rotation of the rotating shaft 11.

[0081] The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical concept of the present invention. For example, the biological lumen into which the medical device 10 is inserted is not limited to a blood vessel, but may be, for example, a vascular tract, a ureter, a bile duct, a fallopian tube, a hepatic duct, etc.

[0082] This application is based on Japanese Patent Application No. 2023-169512 filed on September 29, 2023, the disclosures of which are incorporated herein by reference in their entirety.

[0083] REFERENCE SIGNS LIST 10 Medical device 11 Rotating shaft 12 Storage shaft 20 Drive shaft 40 Guide wire protection tube 42 Main tube 43 Tip member 45 Small diameter section 46 Large diameter section 47 Transition section 48 Second abutment surface 49 First abutment surface 70 Connecting shaft 72 Second step surface 73 Third storage section 80 Cutting section 81 Fitting section 82 Second storage section 83 First storage section 84 First step section 85 First step surface 90 Handle 98 Tube fixing section

Claims

1. A medical device for removing an object from a biological lumen, comprising: a rotating shaft having a rotatable hollow drive shaft and a hollow cutting portion that is rotationally driven by the drive shaft; a guidewire protection tube disposed inside the rotating shaft; and a handle that rotatably houses the base end of the rotating shaft, wherein the guidewire protection tube has a small diameter portion at least a portion of which is disposed inside the cutting portion, and a main tube located proximal to the small diameter portion and at least a portion of which is disposed inside the drive shaft, and wherein the inner diameter of the small diameter portion is smaller than the inner diameter of the main tube.

2. The medical device according to claim 1, wherein the outer diameter of the reduced diameter portion is smaller than the outer diameter of the main tube.

3. The medical device according to claim 1 or 2, characterized in that the material forming the reduced diameter portion has a higher abrasion resistance than the material forming the main tube.

4. The medical device described in claim 1 or 2, characterized in that the cutting portion has a first accommodating portion having an inner diameter capable of accommodating at least a portion of the small diameter portion, a second accommodating portion located on the base end side of the first accommodating portion and having an inner diameter larger than the inner diameter of the first accommodating portion, and a first step portion located between the first accommodating portion and the second accommodating portion and having a first step surface facing in the base end direction, and the guidewire protection tube has a first abutment surface facing in the tip direction and on the base end side of the small diameter portion, the outer diameter of the small diameter portion is smaller than the inner diameter of the first accommodating portion, and the maximum outer diameter of the first abutment surface is larger than the inner diameter of the first accommodating portion.

5. The medical device described in claim 4, characterized in that the rotating shaft has a third accommodating portion located proximal to the second accommodating portion and having an inner diameter smaller than the inner diameter of the second accommodating portion, the guidewire protection tube has a second abutment surface facing in the proximal direction and proximal to the first abutment surface, and the maximum outer diameter of the second abutment surface is larger than the inner diameter of the third accommodating portion.

6. The medical device according to claim 1 or 2, characterized in that the member including the small diameter portion and the member including the main tube are separate bodies.

7. The medical device described in claim 5, characterized in that the axial length between the first abutment surface and the second abutment surface of the guidewire protection tube is shorter than the axial length between the first step surface and the second step surface of the rotating shaft.

8. The medical device described in claim 4, characterized in that the guidewire protection tube is fixed to a tube fixing portion of the handle, and the length from the tube fixing portion to the first abutment surface along the axis of the guidewire protection tube is longer than the length from the tube fixing portion to the first step surface along the axis of the rotating shaft.

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