Medical shaft and medical device

Abstract

The present invention provides: a medical shaft that can be used to smoothly remove a hollow lead implanted in a body, for example; and a medical device using the same.　A medical shaft 1001 comprises a first member 1011 extending along a long-axis direction. The first member 1011 has a first portion A11, a second portion A12 provided closer to a base-end side than the first portion A11, and a third portion A13 provided closer to the base-end side than the second portion A12. The tensile breaking strength of the second portion A12 in the first member 1011, which is measured in such a way that tension is applied in the long-axis direction of the first member 1011, is lower than the tensile breaking strength of the first portion A11 and lower than the tensile breaking strength of the third portion A13.

Description

Medical shafts and medical devices

[0001] The present disclosure relates to medical shafts and medical devices.

[0002] 2. Description of the Related Art When hollow leads extending from a pacemaker or an implantable cardioverter defibrillator (ICD) implanted in the heart are removed from the body, for example, a medical device for removing the leads is used.

[0003] Known examples of such medical devices include a device in which a coil is provided around the outer periphery of a stylet wire (see, for example, Patent Document 1).

[0004] In the above-described medical device, the lead can be removed from the body by expanding the coil inside the lead lumen and then pulling out the medical device while fixing the outer periphery of the expanded coil to the lumen wall of the lead.

[0005] U.S. Pat. No. 4,943,289

[0006] The present specification discloses a medical shaft that allows smooth removal of, for example, a hollow lead implanted in the body, and a medical device using the same.

[0007] One aspect of the medical shaft of the present disclosure is as follows: (1) A first member extending along a longitudinal direction, the first member having a first portion, a second portion provided proximal to the first portion, and a third portion provided proximal to the second portion, wherein the tensile break strength of the second portion of the first member, measured while applying tension to the first member in the longitudinal direction, is smaller than the tensile break strength of the first portion and smaller than the tensile break strength of the third portion. With this configuration, the second portion breaks first due to an excessive load applied in the longitudinal direction, allowing a technician to easily detect the excessive load by visual inspection, etc. (2) The medical shaft of (1) may further include a second member covering a portion of the first member and extending along the longitudinal direction, the second member being joined to the first member at the first portion and the third portion, and the second member may be a coil body. According to this configuration, even if the second portion breaks, the two broken portions of the first member are connected via the coil body. As a result, the medical shaft can be prevented from immediately disassembling. (3) The medical shaft of (1) above may further include a second member covering a portion of the first member and extending along the longitudinal direction, the second member being joined to the first member at the first portion and the third portion, and the second member being a braided member. According to this configuration, even if the second portion breaks, the two broken portions of the first member are connected via the braided member. As a result, the medical shaft can be prevented from immediately disassembling. (4) The medical shaft of (1) above may further include a second member covering a portion of the first member and extending along the longitudinal direction, the second member being joined to the first member at the first portion and the third portion, and the tensile breaking strength of the second member, measured under tension in the longitudinal direction, may be greater than the tensile breaking strength of the second portion of the first member. According to this configuration, when a force that stretches the medical shaft in the longitudinal direction is applied, the second portion of the first member breaks before the second member breaks.By causing the medical shaft to break in stages, first at the second portion of the first member and then at the second member, the operator can easily grasp, by visual inspection, the extent of the excessive load applied to the medical shaft. (5) In the medical shaft of any one of (1) to (4), the outer diameter of the second portion of the first member may be smaller than the outer diameter of the first portion and smaller than the outer diameter of the third portion. According to this configuration, for example, if the entire shaft body is made of the same material, the second portion with the smaller outer diameter will break first due to an excessive load applied to the medical shaft in the longitudinal direction.

[0008] One aspect of the medical device of the present disclosure is as follows: (6) A medical device comprising an elongated main body and an expansion member covering the outer periphery of the distal end of the main body and expandable radially outward, wherein the main body is the medical shaft described in any one of (1) to (5), and the second portion of the first member is provided proximally relative to the expansion member. According to this configuration, for example, by disposing the second portion outside the body even during a procedure, the operator can easily detect excessive load by visual inspection, etc. (7) The medical device of (6) may further comprise a gripping member that is provided proximally relative to the expansion member and connected to the proximal end of the main body, and the second portion of the first member may be provided between the expansion member and the gripping member. According to this configuration, for example, by disposing the second portion outside the body even during a procedure, the operator can easily detect excessive load by visual inspection, etc. (8) The medical device of (6) or (7) may be used to remove a hollow lead from inside the body, and the expansion member may be inserted into the lumen of the lead and fixed to the lead by expanding radially outward. This configuration allows the lead placed inside the body to be removed from the body more safely without applying excessive load to the medical device or the lead.

[0009] As used herein, "distal side" refers to the direction along the longitudinal direction of the main body, in the direction in which the medical device is pushed in (e.g., the distal direction of a lead). "Proximal side" refers to the direction along the longitudinal direction of the main body, in the opposite direction to the distal side. "Distal" refers to the distal end of any component. "Proximal end" refers to the proximal end of any component. "Distal portion" refers to the region between the distal end of any component and a position midway between the distal end and the proximal end of that component. "Proximal end" refers to the region up to the proximal end of any component, which is located proximal to the midway position. "Radial direction" refers to the direction perpendicular to the longitudinal direction of the main body.

[0010] 18 is a schematic side view showing the first embodiment. FIG. 19 is a schematic side view showing an enlarged portion of FIG. 1. FIG. 20 is a schematic cross-sectional view of FIG. 2. FIG. 21 is a schematic view showing a method for measuring tensile breaking strength. FIG. 22 is a schematic cross-sectional view showing an example of the first embodiment when in use. FIG. 23 is a schematic cross-sectional view showing an example of the first embodiment when in use. FIG. 24 is a schematic cross-sectional view showing an example of the first embodiment when in use. FIG. 25 is a schematic cross-sectional view showing an example of the first embodiment when in use. FIG. 26 is a schematic cross-sectional view showing an example of the first member when in use. FIG. 27 is a schematic cross-sectional view showing an example of the first member when in use. FIG. 28 is a schematic cross-sectional view showing an example of the first member when in use. FIG. 29 ... 25. A partially enlarged schematic cross-sectional view showing the third embodiment in use, showing a state where the expansion member is not expanded within the lead. 30. A partially enlarged schematic cross-sectional view showing the third embodiment in use, showing a state where the expansion member is expanded within the lead. 31. A partially enlarged schematic cross-sectional view showing the third embodiment in use, showing a state where the expansion member is expanded within the lead. 32. A partially enlarged schematic cross-sectional view showing the third embodiment in use, showing a state where the expansion member is expanded within the lead. 33. A schematic diagram showing a method for measuring expansion force. 34. A schematic side view showing the fourth embodiment, showing a state where the expansion member is not expanded. 35. A schematic side view showing an enlarged schematic cross-sectional view showing a portion of the expansion member of FIG. 25. 36. A schematic side view showing an enlarged schematic cross-sectional view showing a portion of the expansion member of FIG. 25. 37. A schematic side view showing an enlarged schematic cross-sectional view showing a portion of the fifth embodiment. 38. A conceptual diagram showing the distribution of expansion force of the expansion member. 39. A schematic side view showing the sixth embodiment, showing a state where the expansion member is not expanded. 39. A schematic cross-sectional view showing an enlarged schematic cross-sectional view of a portion of FIG. 30. 39. A schematic cross-sectional view showing an example of the sixth embodiment in use. 39. A schematic cross-sectional view showing an example of the sixth embodiment in use. 39. A schematic cross-sectional view showing an example of the sixth embodiment in use. 39. A schematic cross-sectional view showing an example of the sixth embodiment in use.1 is a schematic cross-sectional view showing one embodiment of a medical device.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the embodiments shown in the drawings. The dimensions of each part shown in the drawings are shown to facilitate understanding of the implementation content and do not necessarily correspond to the actual dimensions.

[0012] <Medical Shaft> The medical shaft of the present disclosure comprises a first member extending along the longitudinal axis direction, the first member having a first portion, a second portion provided on the base end side of the first portion, and a third portion provided on the base end side of the second portion, and the tensile breaking strength of the second portion of the first member, measured while applying tension in the longitudinal axis direction of the first member, is smaller than the tensile breaking strength of the first portion and is also smaller than the tensile breaking strength of the third portion.

[0013] 1 to 3 and 5 to 12, the left side of the figure is the distal end side of the medical shaft, and the right side is the proximal end side (hand side) operated by an operator such as a doctor.

[0014] 1 to 3 are schematic diagrams showing a first embodiment. As shown in Fig. 1 to 3, a medical shaft 1001 includes, for example, a first member 1011 and a second member 1021.

[0015] The first member 1011 is an elongated member extending along the longitudinal direction. The first member 1011 can be formed, for example, of a solid shaft body (hereinafter also referred to as the "shaft body 1011"). The first member 1011 may also be formed of a hollow shaft body.

[0016] The first member 1011 has a first portion A11, a second portion A12, and a third portion A13. The first member 1011 may include portions other than the first portion A11, the second portion A12, and the third portion A13. In this embodiment, the first member 1011 is exemplified as a medical shaft 1001 including the first portion A11, the second portion A12, and the third portion A13.

[0017] The first portion A11 is a portion located, for example, at the distal end of the first member 1011 in the longitudinal direction of the first member 1011. In the medical shaft 1001, the first portion A11 is formed of a large diameter portion 1111 whose diameter decreases toward the distal end. In Fig. 3, D1min represents the smallest outer diameter (minimum outer diameter of the first portion A11) of the first portion A11 (large diameter portion 1111).

[0018] The second portion A12 is a portion provided closer to the base end than the first portion A11. The tip of the second portion A12 may be continuous with the base end of the first portion A11. In the medical shaft 1001, the second portion A12 is formed of a tapered portion 1121 tapering toward the base end, a small diameter portion 1122 having a constant outer diameter, and a tapered portion 1123 tapering toward the tip end. D2min represents the smallest outer diameter of the small diameter portion 1122 of the second portion A12 (the minimum outer diameter of the second portion A12).

[0019] The third portion A13 is a portion provided closer to the proximal end than the second portion A12. The distal end of the third portion A13 may be continuous with the proximal end of the second portion A12. In the medical shaft 1001, the third portion A13 is formed of a large diameter portion 1131 having a constant outer diameter. D3min represents the smallest outer diameter (minimum outer diameter of the third portion A13) of the third portion A13 (large diameter portion 1131).

[0020] The material forming the first member 1011 may be flexible, antithrombogenic, and biocompatible. Examples of materials for the first member 1011 include stainless steel alloys such as SUS304 and superelastic alloys such as Ni-Ti alloys. These materials may be used alone or in combination. For example, the first member 1011 may be formed entirely of stainless steel. The first member 1011 may be a joined body in which a portion formed of stainless steel (e.g., a distal end) and a portion formed of a Ni-Ti alloy (e.g., a proximal end) are joined in series along the longitudinal axis.

[0021] In the medical shaft 1001, the tensile breaking strength of the second portion A12 of the first member 1011, measured by applying tension in the longitudinal direction of the first member 1011, is smaller than the tensile breaking strength of the first portion A11 and is also smaller than the tensile breaking strength of the third portion A13. The configuration of the first member 1011 is not particularly limited as long as it satisfies the above-mentioned tensile breaking strength relationship.

[0022] The outer diameter of the second portion A12 of the first member 1011 may be smaller than the outer diameter of the first portion A11 and smaller than the outer diameter of the third portion A13. In the longitudinal direction, the minimum outer diameter D2min of the second portion A12 may be smaller than both the minimum outer diameter D1min of the first portion A11 and the minimum outer diameter D3min of the third portion A13. As a result, for example, if the entire first member 1011 is made of the same material, the second portion A12, which has the smaller outer diameter, will break first due to an excessive load applied to the medical shaft 1001 in the longitudinal direction.

[0023] In this embodiment, the first portion A11 and the third portion A13 are large diameter portions 1111 and 1131, and the second portion A12 is formed of a tapered portion 1121, a thin diameter portion 1122, and a tapered portion 1123. As shown in FIG. 3 , the minimum outer diameter D2min of the second portion A12 is smaller than the minimum outer diameter D1min of the first portion A11 and smaller than the minimum outer diameter D3min of the third portion A13. Because the entire first member 1011 is formed from the same material, the thin diameter portion 1122 of the second portion A12 determines the tensile breaking strength of the first member 1011. As a result, if an excessive load is applied to the medical shaft 1001 along the longitudinal direction, the shaft body 1011 will first break at the thin diameter portion 1122, which has the minimum outer diameter D2min.

[0024] A method for measuring tensile breaking strength will now be described. FIG. 4 is a schematic diagram illustrating the method for measuring tensile breaking strength. As shown in FIG. 4, tensile breaking strength can be measured using a tension-compression testing machine 1500. Specifically, a sample S (here, a medical shaft processed to a predetermined length) is used, and one end of the sample S is fixed to an upper check 1501 and the other end is fixed to a lower chuck 1502. Next, the sample S is pulled at a speed of 10 mm / min while widening the gap between the upper check 1501 and the lower chuck 1502. During this process, the sample S is pulled until it breaks while measuring the load applied between the chucks 1501 and 1502. The load at which the sample S breaks is the tensile breaking strength of the sample S.

[0025] The second member 1021 is a member that extends along the longitudinal direction and covers a portion of the first member 1011. The second member 1021 is joined to the first portion A11 and the third portion A13 of the first member 1011 at joints 1001a. The second member 1021 is not particularly limited as long as it satisfies the above-described configuration.

[0026] The second member 1021 of this embodiment is formed of a coil body (hereinafter also referred to as the "coil body 1021"). The coil body 1021 is extendable along the longitudinal axis. The coil body 1021 is disposed so as to cover the outer periphery of the shaft body 1011.

[0027] The coil body 1021 can be formed, for example, by winding a wire w1001 around the longitudinal axis of the first member 1011. The wire w1001 of the coil body 1021 can be at least one of a solid wire and a twisted wire. A solid wire refers to a single single wire. A twisted wire refers to a bundle of wires formed by twisting multiple single wires together in advance. The coil body 1021 can be formed by winding the wire w1001 in at least one of a single strand and multiple strands. The wire 1001 may be a round wire (circular in cross section) or a flat wire (rectangular in cross section).

[0028] The tensile breaking strength of the second member 1021, measured by applying tension in the longitudinal direction, may be greater than the tensile breaking strength of the second portion A12 of the first member 1011. The medical shaft 1001 is formed so that the tensile breaking strength of the coil body 1021 is greater than the tensile breaking strength of the second portion A12 of the shaft body 1011.

[0029] As a result, when a force stretching the medical shaft 1001 in the longitudinal direction is applied, the second portion A12 of the shaft body 1011 breaks before the coil body 1021 breaks. The medical shaft 1001 breaks in stages, first at the second portion A12 of the first member (shaft body 1011) and then at the second member (coil body 1021), allowing the operator to easily grasp, by visual inspection or the like, how much excessive load is being applied to the medical shaft 1001.

[0030] There is no particular limitation on the material that forms the second member 1021. Examples of the material that can be used for the second member 1021 include stainless steel such as SUS304 and SUS316, and resin materials such as reinforced plastics.

[0031] The coil body 1021 is joined to the first portion A11 and the third portion A13 of the shaft body 1011 at the joint 1001a. The coil body 1021 is not joined to the second portion A12 of the shaft body 1011. The method for joining the coil body 1021 and the shaft body 1011 is not particularly limited. Examples of the joining method include a method using a brazing material or a solder material. Examples of the brazing material and the solder material include alloys such as Sn—Pb alloy, Pb—Ag alloy, Sn—Ag alloy, and Au—Sn alloy.

[0032] The following describes how the medical shaft 1001 can be used. The medical shaft 1001 can be used, for example, as a shaft for a guidewire or a catheter. When the medical shaft 1001 is used as a guidewire, the operator can detect breakage of the second portion A12 during use of the guidewire and thereby detect that excessive load is being applied to the guidewire. Below, an example of a procedure in which the medical shaft is applied to a guidewire is given. The procedure is usually performed with the second portion A12 of the shaft main body 1011 exposed to the outside of the body so that breakage of the second portion A12 and the coil body 1021 can be visually confirmed.

[0033] First, the medical shaft 1001 (hereinafter also referred to as a "guidewire") is inserted into a body cavity such as a blood vessel. Specifically, the operator inserts the guidewire into the body cavity while grasping the proximal end of the guidewire, and advances the guidewire to the site to be treated in the blood vessel. Next, the proximal end of the guidewire is inserted into the lumen of a device such as a dilator, and the device is advanced to the site to be treated using the guidewire as a guide. Next, the desired treatment is performed using the device.

[0034] After the treatment using the device is completed, the device and the guidewire are withdrawn from the body in this order. Specifically, after withdrawing the device using the guidewire as a guide, the technician pulls the guidewire toward the proximal end while grasping the proximal end of the guidewire. During this process, excessive load may be applied to the guidewire (medical shaft 1001) due to factors such as high friction between the guidewire and the blood vessel. When excessive load is applied along the longitudinal direction of the medical shaft 1001, the second portion A12 of the shaft body 1011 breaks first, as shown in FIG. 5 . The technician can detect that excessive load is being applied to the medical shaft 1001 by visually confirming the breakage of the second portion A12 or by sensing the impact at the time of breakage. Immediately after the breakage, the two portions of the broken first member 1011 (the portion including the first portion A11 and the portion including the third portion A13) are connected via the coil body 1021, and therefore, as shown in Figure 6, the medical shaft 1001 does not immediately disassemble.

[0035] When a further load is applied to the medical shaft 1001 in the longitudinal direction, the coil body 1021 stretches in the longitudinal direction. The operator can estimate the load acting on the medical shaft 1001 by checking the deformation of the coil body 1021. When a further load is applied to the medical shaft 1001 in the longitudinal direction, the coil body 1021 breaks, as shown in Fig. 7. By visually confirming the breakage of the coil body 1021 or sensing the impact at the time of breakage, the operator can detect that a further load is being applied and can take measures such as interrupting the procedure.

[0036] As described above, since the medical shaft 1001 has the above-described configuration, when excessive load is applied in the longitudinal direction, the second part A12 breaks first, and the operator can easily detect the excessive load by visual inspection, etc.

[0037] The medical shaft 1001 is provided with a coil body 1021. As a result, even if the second portion A12 breaks, the two broken portions of the first member 1011 are connected via the coil body 1021. As a result, the medical shaft 1011 can be prevented from immediately disassembling.

[0038] In addition, if an even greater load is applied to the medical shaft 1001 in the longitudinal direction, the second portion A12 will break, followed by the coil body 1021. This allows the operator to easily detect, by visual inspection or the like, that an even greater load is being applied. As a result, the safety of the procedure can be further improved.

[0039] In the above-described embodiment, the medical shaft 1001 has been described, in which the first portion A11 and the third portion A13 are large-diameter portions 1111 and 1131, and the second portion A12 is composed of a tapered portion 1121, a thin-diameter portion 1122, and a thin-diameter portion 1123. The shapes of the first, second, and third portions are not limited to the above shapes, as long as the tensile strength of the second portion is lower than that of the first portion and lower than that of the third portion. For example, the second portion A22 may be composed of a tapered portion 1221 and a tapered portion 1222 (see FIG. 8 ). The second portion A32 may be composed of a tapered portion 1231 and a thin-diameter portion 1232 (see FIG. 9 ). The second portion A42 may be composed only of a thin-diameter portion 1241 (see FIG. 10 ).

[0040] [Second Embodiment] Fig. 11 is a schematic cross-sectional view showing a second embodiment. As shown in Fig. 11, a medical shaft 1002 includes, for example, a first member 1011 and a second member 1022. The second embodiment differs from the first embodiment in that it includes the second member 1022. The configuration of the first member 1011 is the same as that of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted. The configuration of the second member 1022, other than the configuration of the second member 1022 described below, is the same as that of the second member 1021 of the first embodiment. The usage of the medical shaft 1002 is the same as that of the first embodiment.

[0041] The second member 1022 is a member that extends along the longitudinal direction and covers a portion of the first member 1011. The second member 1022 is joined to the first portion A11 and the third portion A13 of the first member 1011 at joints 1002a.

[0042] The second member 1022 of this embodiment is formed of a braided element (hereinafter also referred to as "braided element 1022"). The braided element 1022 is a member in which wires w1002 are woven into a mesh. The wires w1002 may be, for example, at least one of a solid wire and a twisted wire. The braided element 1022 is stretchable along the longitudinal axis. The braided element 1022 is formed in a cylindrical shape so as to cover the outer periphery of the first member 1011.

[0043] There is no particular limitation on the material of the wires w1002 that form the braid 1022. Examples of the material of the wires w1002 include stainless steel such as SUS304 and SUS316, and resin materials such as reinforced plastics.

[0044] The braided body 1022 is joined to the first portion A11 and the third portion A13 of the shaft body 1011 at joints 1002a. The braided body 1022 is not joined to the second portion A12 of the shaft body 1011. The method for joining the braided body 1022 to the shaft body 1011 is not particularly limited. As the joining method, for example, the same method as the above-described method for joining the coil body 1021 to the shaft body 1011 can be used.

[0045] As described above, since the medical shaft 1002 has the above-mentioned configuration, when excessive load is applied in the longitudinal direction, the second part A12 breaks first, and the operator can easily detect the excessive load by visual inspection, etc.

[0046] The medical shaft 1002 is provided with a braided body 1022. As a result, even if the second portion A12 breaks, the two broken portions of the first member 1011 are connected via the braided body 1022. As a result, the medical shaft 1002 can be prevented from immediately disintegrating.

[0047] In addition, if an even greater load is applied to the medical shaft 1002 in the longitudinal direction, the second portion A12 will break, followed by the braided body 1022. This allows the operator to easily notice, by visual inspection or the like, that an even greater load is being applied. As a result, the safety of the procedure can be further improved.

[0048] In the first embodiment described above, the medical shaft 1001 in which the second member is a coil body 1021 has been described. In the second embodiment, the medical shaft 1002 in which the second member is a braided body 1022 has been described. The second member is not particularly limited. As shown in FIG. 12 , the second member 1023 may be an expandable tube. The tube may be made of a resin material or a metal material.

[0049] <Medical Device> The medical device disclosed herein is, for example, a device for removing a lead placed in the body. During use, the medical device is inserted into the lumen of the lead and pushed through the lumen of the lead until the tip is positioned near the tip of the lead. With the tip of the medical device positioned near the tip of the lead, the pusher member is manually moved toward the distal end of the medical device by the operator (physician). The tip of the pusher member pushes the proximal end of the expansion member toward the distal end, compressing the expansion member along the longitudinal direction. As the expansion member is compressed, it expands radially outward from the medical device. As the expansion member expands, it begins to expand from the distal end of the expansion member, and then expansion progresses toward the proximal end of the expansion member. The distal end of the expansion member, which expanded first, abuts against the inner circumference of the lead, fixing the distal end of the medical device to the distal end of the lead. Then, the portion of the expansion member proximal to the distal end abuts against the inner circumference of the lead, just like the tip. The operator pulls the medical device temporarily fixed to the lead toward the proximal end (proximal side), thereby removing the lead.

[0050] 13 to 23, 25 to 28, and 30 to 35, the left side of the figure is the distal end side into which the medical device is pushed, and the right side is the proximal end side (hand side) operated by an operator such as a doctor.

[0051] 13 to 23 are schematic diagrams showing a third embodiment. As shown in Fig. 13, a medical device 1 generally includes a main body 11, a tip fixation portion 21, an expansion member 31, a pushing member 41, a fixing mechanism 51, and a gripping member 61.

[0052] The main body 11 is an elongated member. Specifically, the main body 11 can be formed, for example, by a core shaft (hereinafter also referred to as "core shaft 11") formed in a linear shape from a metal such as a stainless steel alloy. The main body 11 may be formed, for example, so that its outer diameter varies along the longitudinal direction. In the medical device 1, the portion of the main body 11 located inside the expansion member 31 is a small diameter portion 111 having a constant outer diameter. The portion of the main body 11 located closer to the base end than the small diameter portion 111 is a large diameter portion 112 having an outer diameter larger than the small diameter portion 111. The main body 11 extends from the tip of the expansion member 31 to the tip of the gripping member 61.

[0053] The material for forming the main body 11 preferably has antithrombogenicity and biocompatibility while ensuring flexibility. Examples of such materials include stainless steel alloys such as SUS304 and superelastic alloys such as Ni-Ti alloys.

[0054] The tip fixing portion 21 is a portion where the tip of the main body 11 and the tip of the expansion member 31 are integrally fixed. As shown in Fig. 14, the tip fixing portion 21 can be specifically formed, for example, so that its tip has a generally hemispherical shape that is convexly curved toward the tip side. This can reduce resistance when the medical device 1 advances through the lumen of the lead, for example. As a result, the medical device 1 can be smoothly inserted into the lumen of the lead.

[0055] The tip fixing portion 21 can be formed, for example, by melting a portion of the member that forms the core shaft 11 and / or the expansion member 31 (e.g., a coil), or by using a brazing material or solder material to join the core shaft 11 and the expansion member 31. Examples of brazing material and solder material include alloys such as Sn—Pb alloy, Pb—Ag alloy, Sn—Ag alloy, and Au—Sn alloy.

[0056] The expansion member 31 is a member that covers the outer periphery of the main body 11 and is expandable radially outward. Specifically, as shown in Fig. 14, the expansion member 31 may be formed, for example, as a coil (hereinafter also referred to as "coil 31") in which a wire w1 is wound around the outer periphery of the main body 11. This makes it possible to easily form the expansion member 31.

[0057] The wire w1 forming the coil 31 can be, for example, at least one of a solid wire and a twisted wire. A solid wire means one single wire. A twisted wire means a bundle of wires formed by twisting multiple single wires together in advance. The coil 31 can be formed by winding the wire w1 in at least one of a single-strand and multiple-strand configuration. The wire w1 may have, for example, a circular cross section. The wire w1 may have a rectangular cross section. In the medical device 1, the wire w1 is a single wire with a circular cross section. The coil 31 is a four-strand coil formed by winding four wires w1 together.

[0058] The material of the wire w1 forming the coil 31 is not particularly limited as long as it has the ease of expansion (expandability), antithrombogenicity, and biocompatibility of the expansion member 31. Examples of such materials include stainless steel alloys such as SUS316 and superelastic alloys such as Ni-Ti alloys.

[0059] The coil 31 has a first portion 31A, a second portion 31B, and a third portion 31C.

[0060] 14 , in the medical device 1, the distal end portion of the coil 31 is the first portion 31A. The proximal end portion of the coil 31 that is continuous with the first portion 31A is the second portion 31B. The proximal end portion of the coil 31 that is continuous with the second portion 31B is the third portion 31C. That is, the second portion 31B is the portion of the coil 31 that is located closer to the proximal end than the first portion 31A. The third portion 31C is the portion of the coil 31 that is located closer to the proximal end than the second portion 31B.

[0061] The tip of the expansion member 31 (the tip of the first portion 31A) may be located, for example, within 10 mm from the tip of the main body 11 toward the base end in the longitudinal direction of the main body 11. This allows the tip portion of the expansion member 31 to be located near the tip of the main body 11, so that the expansion member 31 can be expanded at the tip portion of the medical device 1.

[0062] As shown in FIG. 15 , the maximum width a1 of the wire w1 at the first portion 31A is smaller than the maximum width a2 of the wire w1 at the second portion 31B. Furthermore, in the medical device 1, the maximum width a1 of the wire w1 at the distal end (first portion 31A) of the coil 31 is smaller than the maximum width a3 of the wire w1 at the proximal end (third portion 31C) of the coil 31. In this disclosure, the "width of the wire" refers to the size of the wire in a direction perpendicular to the longitudinal direction of the wire. The "maximum width of the wire" refers to the maximum width of the wire. For example, if the cross section of the wire is circular (the wire is round), the maximum width of the wire is the diameter of the wire. If the cross section of the wire is rectangular (the wire is flat), the maximum width of the wire is the maximum thickness of the wire (the length of the short side of the wire).

[0063] In the medical device 1, the wire w1 is a round wire, and therefore the diameter of the wire w1 is the maximum width of the wire w1. The maximum width of the wire w1 in the first portion 31A is constant along the longitudinal direction. The maximum width of the wire w1 in the second portion 31B is constant along the longitudinal direction. The maximum width of the wire w1 in the third portion 31C is constant along the longitudinal direction.

[0064] The maximum width of the wire w1 may gradually increase from the distal end toward the proximal end of the coil 31. Specifically, the maximum width of the wire w1 may gradually increase from the distal end of the first portion 31A toward the proximal end of the third portion 31C. This allows the expansion member 31 to be gradually expanded from the distal end toward the proximal end.

[0065] In the first portion 31A and the second portion 31B, adjacent wires w1 are not fixed to each other. In the third portion 31C, at least some of the adjacent wires w1 are fixed to each other. In the third portion 31C of the medical device 1, the four wires w1 wound in four rows are joined to each other. This allows the rigidity of the coil 31 in the third portion 31C to be higher than the rigidity of the first and second portions 31A and 31B.

[0066] 16 is a schematic side view showing a state in which the expansion member 31 of the medical device 1 is expanded when the medical device 1 is not inserted into the lumen of the lead 80 ( FIG. 21 ). As described above, when the lead 80 is removed from the body, the expansion member 31 is expanded while inserted into the lead 80, and the expansion portions (first portion 31A, second portion 31B) of the expansion member 31 are expanded until they abut against the inner circumference of the lead 80. One of the purposes of the medical device 1 is to ensure that the expansion portions (first portion 31A, second portion 31B) more reliably abut against the inner circumference of the lead 80 when the expansion member 31 is expanded inside the lead 80. The maximum widths (D1, D2) of the expansion portions (first portion 31A, second portion 31B) when expanded when not inserted into the lead 80 are formed to be larger than the inner diameter of the lead 80. By increasing the maximum widths (D1, D2) of the expansion sections (first region 31A, second region 31B) when expanded without being inserted into the lead 80, the expansion force of the expansion member 31 can be increased, thereby improving the fixation force between the lead 80 and the medical device 1. The greater the pitch (p1, p2) of the wires w1 of the expansion member 31, the greater the maximum widths (D1, D2) when expanded. In the medical device 1, the pitch p1 of the wires w1 in the first region 31A is greater than the pitch p2 of the wires w1 in the second region 31B. This allows the maximum width D1 of the expansion member 31 at the first region 31A when expanded to be greater than the maximum width D2 of the expansion member 31 at the second region 31B when not inserted into a lumen such as a lead 80. In this disclosure, the "maximum width of the expansion member" refers to the maximum dimension of the expansion member in the radial direction.

[0067] In the medical device 1, the pitch p1 of the wires w1 at the distal end (first portion 31A) of the coil 31 is larger than the pitch p3 of the wires w1 at the proximal end (third portion 31C) of the coil 31. This allows the maximum width D1 of the distal end (first portion 31A) of the coil 31 when the expansion member 31 is expanded to be larger than the maximum width D3 of the proximal end (third portion 31C) of the coil 31 when not inserted into the lumen of a lead or the like.

[0068] In the medical device 1, the pitch p1 of the wires w1 in the first portion 31A is constant along the longitudinal direction, the pitch p2 of the wires w1 in the second portion 31B is constant along the longitudinal direction, and the pitch p3 of the wires w1 in the third portion 31C is constant along the longitudinal direction.

[0069] The pitch of the wire w1 may gradually decrease from the distal end toward the proximal end of the coil 31. This allows the maximum width of the coil 31 when the expansion member 31 is expanded to gradually increase from the proximal end toward the distal end of the coil 31.

[0070] The expansion member 31 expands radially outward, for example, by pushing its base end toward the distal end with a pusher member 41 (described later). In the medical device 1, the distal end of the expansion member 31 is fixed at the distal fixation portion 21. Therefore, by pushing with the pusher member 41, the expansion member 31 is compressed and expanded along the longitudinal direction of the main body 11. The maximum width of the wires w1 at the first portion 31A of the expansion member 31 is smaller than the maximum width of the wires w1 at the portions proximal to the first portion 31A (the second portion 31B and the third portion 31C). Therefore, the stress generated at the distal end of the expansion member 31 due to longitudinal compression of the expansion member 31 is greater than the stress generated at the proximal end of the expansion member 31 due to longitudinal compression of the expansion member 31. As a result, due to the greater stress at the distal end of the expansion member 31, the distal end (first portion 31A) of the expansion member 31 begins to expand radially outward first. That is, when the expansion member 31 expands, the distal end of the expansion member 31 begins to expand radially outward before the proximal end of the expansion member 31. After the first portion 31A begins to expand, the second portion 31B begins to expand.

[0071] When the medical device 1 is not inserted into the lumen of a lead or the like, when the expansion member 31 expands, the maximum width D1 of the distal end (first portion 31A) of the expansion member 31 becomes greater than the maximum width D3 of the proximal end of the expansion member 31. As a result, when the expansion member 31 expands in the lumen of the lead, the force exerted by the distal end of the expansion member 31 against the lumen wall of the lead is greater than the force exerted by the proximal end of the expansion member 31 against the lumen wall of the lead. In other words, the expansion force of the distal end of the expansion member 31 is greater than the expansion force of the proximal end of the expansion member 31. This is because the pitch of the wires w1 forming the coil 31 is greater at the distal end than at the proximal end of the coil 31. As a result, for example, when the expansion member 31 expands, the distal end of the expansion member 31 can be more firmly fixed to the distal lumen wall of the lead. In this disclosure, the "expansion force" refers to the degree of force with which the expansion member presses the lumen wall of the lead or the like radially outward.

[0072] Fig. 24 is a schematic diagram showing a method for measuring the expansion force. The expansion force can be measured, for example, using an expansion force measuring device 70 as shown in Fig. 24. The expansion force can be obtained by measuring, with a load meter 71, the load that presses against a probe 72 when the expansion member expands radially outward. The value of the expansion force can be the arithmetic mean of five measured values.

[0073] Figure 29 is a conceptual diagram showing the distribution of the expansion force of the expansion member. In the figure, the horizontal axis represents the longitudinal position of the expansion member, and the vertical axis represents the expansion force. As shown in Figure 29, the expansion force increases toward the distal end of the coil and decreases toward the proximal end.

[0074] The pushing member 41 is a member that is movable along the longitudinal direction of the main body 11 and pushes the base end of the expansion member 31 toward the distal end side, thereby compressing the expansion member 31 along the longitudinal direction.

[0075] The shape of the pushing member 41 is not particularly limited. Specifically, as shown in FIG. 17 , the pushing member 41 may be formed, for example, as a cylindrical body (hereinafter also referred to as the "cylindrical body 41") that covers the outer periphery of the main body 11. This allows the pushing member 41 to be easily formed. In the medical device 1, the maximum width r1 of the distal end 41a of the pushing member 41 is smaller than the maximum width r2 of the proximal end of the expansion member 31 that abuts against the distal end 41a of the pushing member 41. In the medical device 1, the maximum width of the pushing member 41 decreases toward the distal end. In the present disclosure, the "maximum width of the pushing member" refers to the maximum dimension of the pushing member in the radial direction. The "maximum width of the proximal end of the expansion member" refers to the maximum dimension of the proximal end of the expansion member in the radial direction. Having the maximum width r1 smaller than the maximum width r2 reduces the risk of the distal end of the pushing member 41 getting caught in the lumen of the lead 80, for example, and facilitates insertion of the medical device 1 into the lead 80. Since the maximum width of the pushing member 41 decreases toward the tip side, the rigidity of the pushing member 41 decreases toward the tip side, allowing the pushing member 41 to easily pass through curved blood vessels.

[0076] The rigidity of the proximal end of the pushing member 41 may be greater than the rigidity of the distal end of the pushing member 41. This improves the pushability of the pushing member 41 and ensures that the pushing force is transmitted from the proximal end to the distal end of the pushing member 41. As shown in FIG. 17 , the pushing member 41 may have, for example, a reinforcing coil 411 that covers the outer periphery of the proximal end of the pushing member 41. The reinforcing coil 411 can be formed, for example, by winding a wire w2 around the outer periphery of the cylindrical body 41. This increases the rigidity of the proximal end of the pushing member 41. The reinforcing coil 411 may be fixed to the cylindrical body 41.

[0077] There is no particular limitation on the material of the wires w2 forming the reinforcing coil 411. Examples of such materials include stainless steel alloys such as SUS304.

[0078] 17 , a position marker 413 may be provided on the outer periphery of the proximal end of the pushing member 41. The configuration of the position marker 413 is not particularly limited as long as it allows the operator to identify the position of the proximal end of the pushing member 41. The color of the position marker 413 may be different from the color of the pushing member 41 so that the position of the marker can be visually confirmed. The tactile feel of the position marker 413 may be different from the tactile feel of the pushing member 41. This makes it easy to grasp the positional relationship between the main body 11 and the pushing member 41, and allows the fixing mechanism 51, which will be described later, to be operated smoothly.

[0079] As shown in FIG. 17 , a pushing loop member 412 may be provided at the proximal end of the pushing member 41. Specifically, the pushing loop member 412 is formed in a loop shape so that, for example, forceps, tweezers, or the like can be inserted. This allows the pushing member 41 to be easily pushed toward the distal end using forceps, tweezers, or the like. The pushing loop member 412 may have its proximal end fixed between the outer periphery of the proximal end of the pushing member 41 and the inner periphery of the reinforcing coil 411, for example, so that the loop portion 412 a is located toward the distal end. This improves the bonding strength between the pushing loop member 412 and the pushing member 41.

[0080] The maximum width s1 of the pushing loop member 412 may be smaller than the maximum width s2 of the reinforcing coil 411. In this disclosure, the "maximum width of the pushing loop member" refers to the maximum dimension of the pushing loop member in a direction perpendicular to the longitudinal direction of the pushing member 41. The "maximum width of the reinforcing coil" refers to the maximum dimension of the reinforcing coil in the radial direction. This reduces interference between the pushing loop member 412 and other components (e.g., the lead 80, the sheath 90, etc.), allowing the medical device 1 to be easily inserted into the lead.

[0081] The fixing mechanism 51 is a mechanism capable of fixing the main body 11 and the pushing member 41. The fixing mechanism 51 fixes the main body 11 to the pushing member 51 by engaging the outer periphery of the main body 11 with the pushing member 51. As shown in FIG. 18 , the fixing mechanism 51 may have a curved portion 113 in which a portion of the core shaft 11 is curved. The curved portion 113 can be formed, for example, to protrude in a direction perpendicular to the longitudinal axis of the main body 11. As shown in FIG. 19 , the curved portion 113 abuts against the inner circumferential surface 41b of the pushing member 41, thereby fixing the main body 11 and the pushing member 41 due to the frictional force between the main body 11 and the pushing member 41. This allows the main body 11 and the pushing member 41 to be fixed with a simple configuration.

[0082] The fixing mechanism 51 may be formed with only one curved portion 113, or may be formed with two or more curved portions 113. The fixing mechanism 51 may have, for example, a first curved portion 113A in which the core shaft 11 is curved in a first direction, and a second curved portion 113B in which the core shaft 11 is curved in a second direction different from the first direction. In the medical device 1, the fixing mechanism 51 has the first curved portion 113A and the second curved portion 113B arranged in a zigzag pattern. In the medical device 1, the first curved portion 113A and the second curved portion 113B are formed so that the main body 11 itself meanders with respect to the longitudinal axis of the main body 11. This allows the main body 11 and the pushing member 41 to be fixed with a simple configuration.

[0083] As shown in FIGS. 18 and 19 , the main body 11 may have a first marker 511 at a location distal to the tip of the fixing mechanism 51. The main body 11 may also have a second marker 512 at a location proximal to the base of the fixing mechanism 51. By providing such markers 511, 512, it is possible to easily determine whether the fixing mechanism 51 is operating. The first and second markers 511, 512 are not particularly limited as long as the operator can identify their positions. The colors of the first and second markers 511, 512 may be different from the colors of other parts (e.g., the pushing member 41, the gripping member 61, etc.) so that the positions of the markers can be visually confirmed. The tactile sensation of the first and second markers 511, 512 may be different from the tactile sensation of other parts.

[0084] The first marker 511 and the second marker 512 may each be a metal oxide coating formed on the surface of the main body 11. The metal oxide coating can be formed, for example, by forming the main body 11 from a metal material such as a stainless steel alloy or a nickel-titanium alloy and heat-treating the surface of this metal material in an oxidizing atmosphere. The color of the metal oxide coating may be different from the color of the metal of the main body 11. The tactile feel of the metal oxide coating may be different from the tactile feel of the metal of the main body 11. This makes it possible to easily form the first and second markers 511, 512.

[0085] The gripping member 61 is a flexible member that is disposed closer to the base end than the pushing member 41 and is connected to the base end of the main body 11. The gripping member 61 is gripped by the operator when operating the medical device 1. As shown in Fig. 20 , the gripping member 61 may be connected by fixing its tip to the base end of the main body 11.

[0086] The shape of the gripping member 61 is not particularly limited. The gripping member 61 may be formed, for example, by spirally winding the wire w3. This allows the gripping member 61 to be easily and reliably gripped. For example, by wrapping the gripping member 61 around the hand, the operator can reliably pull the lead out of the body when removing the lead. The length of the gripping member 61 in the longitudinal direction may be greater than the length of the pusher member 41 in the longitudinal direction. This allows the gripping member 61 to be easily wrapped around the operator's hand, for example.

[0087] In the medical device 1, a gripping loop member 611 is provided at the proximal end of a tubular gripping member 61. Specifically, the gripping loop member 611 is formed in a loop shape so that, for example, forceps, tweezers, or the like can be inserted. The distal end of the gripping loop member 611 may be fixed to the inner circumference of the proximal end of the tubular gripping member 61 so that the loop portion 611a is located on the proximal end side. This allows, for example, when using a sheath 90 described below, the medical device 1 to be easily pulled while hooking forceps or the like on the gripping loop member 611.

[0088] The maximum width b1 of the gripping loop member 611 may be smaller than the maximum width b2 of the gripping member 61. In the present disclosure, the "maximum width of the gripping loop member" refers to the maximum dimension of the gripping loop member in a direction perpendicular to the longitudinal direction of the gripping member 61. This can reduce interference between the gripping loop member 611 and other members (e.g., the gripping member 61, the sheath 90, etc.), thereby improving the operability of the medical device 1.

[0089] Next, a description will be given of how the medical device 1 is used with reference to Figures 21 to 23. Here, a description will be given of a procedure for removing a hollow lead 80 extending from a pacemaker implanted in the heart to the outside of the body using the medical device 1. The lead 80 shown has a first electrode 81 located at the tip of the lead 80 and a second electrode 82 located closer to the base end than the first electrode 81.

[0090] First, using the medical device 1 with the expansion member 31 in an unexpanded state, the expansion member 31 is inserted into the lumen 80h of the lead 80, as shown in Fig. 21. Specifically, the distal fixation portion 21 of the medical device 1 is inserted into the lumen 80h from the proximal end of the lead 80 that has been detached from the pacemaker. Next, the medical device 1 is pushed forward in the lumen 80h, and the medical device 1 is delivered so that the distal end of the expansion member 31 is positioned in the lumen of the lead 80 distal to the second electrode 82.

[0091] Next, the fixation between the main body 11 and the pushing member 41 is released. Specifically, the engagement between the main body 11 and the pushing member 41 by the fixing mechanism 51 is released by moving the pushing member 41 toward the distal end along the longitudinal direction of the main body 11. At this time, as shown in FIG. 18 , the first curved portion 113A and the second curved portion 113B provided on the main body 11 move away from the inner circumferential surface 41b of the pushing member 41, thereby releasing the engagement between the main body 11 and the pushing member 41.

[0092] Next, the expansion member 31 is expanded radially outward to secure the expansion member 31 to the lead 80. Specifically, while the distal end of the pushing member 41 is in contact with the proximal end of the expansion member 31, the pushing member 41 is further moved distally along the longitudinal direction of the main body 11. At this time, as shown in FIG. 22 , the expansion member 31 begins to expand radially outward from the first portion 31A. As shown in FIG. 23 , by further moving the pushing member 41 distally, the second portion 31B expands. In the expanded state, the outer periphery of the expansion member 31 (first portion 31A) abuts against the inner periphery (inner cavity wall 80a) of the lead 80 distal to the second electrode 82. The expansion of the expansion member 31 progresses from the distal end toward the proximal end of the expansion member 31, and the contact area between the expansion member 31 and the lead 80 expands. This allows the lead 80 and the medical device 1 to be secured at a more distal position of the lead 80.

[0093] Next, the lead 80 inside the body is removed outside the body. Specifically, the medical device 1 (see FIG. 23 ), with the expansion member 31 fixed to the lead 80, is pulled toward the proximal end while the gripping member 61 is grasped, thereby removing the lead 80 outside the body. Sometimes, tissue may adhere to the lead 80. In such cases, as shown in FIG. 21 , a sheath 90 may be placed over the outer surface of the lead 80, and the adhesions may be removed using a dissection device 91 provided at the distal end of the sheath 90. Examples of the dissection device 91 include a device provided at the distal end of the sheath 90 that irradiates the distal end with laser light to remove adhesions. This allows the hollow lead 80 inside the body to be removed outside the body using the medical device 1.

[0094] As described above, because the medical device 1 has the above-described configuration, the distal end of the expansion member 31 begins to expand radially outward before the proximal end of the expansion member 31. As a result, for example, when removing a hollow lead 80 from the body, the distal end of the expansion member 31 can be fixed distal to the lead 80, and the hollow lead 80 implanted in the body can be smoothly removed.

[0095] The medical device 1 includes a pushing member 41. As a result, the pushing member 41 can compress the expansion member 31 along the longitudinal direction of the main body 11, and the expansion member 31 can be reliably expanded.

[0096] The medical device 1 is provided with a fixing mechanism 51. As a result, the main body 11 and the pushing member 41 can be fixed together, and when the medical device 1 is not in use, the expansion member 31 can be prevented from expanding.

[0097] The medical device 1 includes a gripping member 61. As a result, by operating the medical device 1 while gripping the gripping member 61, the expansion member 31 can be easily expanded and the lead 80 can be easily pulled out.

[0098] [Fourth Embodiment] Figures 25 to 27 are schematic diagrams showing a fourth embodiment. As shown in Figure 25, the medical device 2 generally comprises a main body 11, a tip fixing portion 21, an expansion member 32, a pushing member 41, a fixing mechanism 51, and a gripping member 61. The fourth embodiment differs from the third embodiment in that it comprises an expansion member 32. The configurations of the main body 11, tip fixing portion 21, pushing member 41, fixing mechanism 51, and gripping member 61 are the same as those of the third embodiment. Therefore, the same components are denoted by the same reference numerals and detailed descriptions thereof will be omitted. The configuration is the same as that of the expansion member 31, except for the configuration of the expansion member 32, which will be described below. The usage of the medical device 2 is the same as that of the medical device 1.

[0099] The expansion member 32 is a member that covers the outer periphery of the main body 11 and is expandable radially outward. The expansion member 32 of the medical device 2 is formed of a coil (hereinafter also referred to as the “coil 32”) in which a wire w1 is wound around the outer periphery of the main body 11.

[0100] 26 , the expansion member 32 of the medical device 2 has an expansion section 321 that expands radially outward and a non-expanding section 322 that is located distal to the expansion section 321 and does not expand radially outward. The coil 32 of the medical device 2 has a fourth section 32D distal to the first section 32A. In the medical device 2, for example, the expansion section 321 corresponds to the first section 32A, the second section 32B, and the third section 32C, and the non-expanding section 322 corresponds to the fourth section 32D.

[0101] As shown in FIG. 27 , the non-expandable portion 322 has a joint portion 322a and a non-joint portion 322b. The distal end and proximal end of the non-expandable portion 322 are fixed to the main body 11 at the joint portions 322a. The portion of the non-expandable portion 322 between the distal end and proximal end of the non-expandable portion 322 is the non-joint portion 322b, which is not fixed to the main body 11. The non-expandable portion 322 does not expand radially outward. Because the coil 32 is fixed at both ends of the non-joint portion 322b at the joint portions 322a, the coil 32 of the non-expandable portion 322 is not compressed along the longitudinal direction of the main body 11. For this reason, the non-expandable portion 322 does not expand radially outward even when the pushing member 41 is moved, for example.

[0102] The bending rigidity of the non-bonded portion 322b may be smaller than the bending rigidity of any of the bonded portions 322a. In the medical device 2, the bending rigidity of the non-bonded portion 322b is smaller than the bending rigidity of the bonded portions 322a provided at the distal and proximal ends of the non-expandable portion 322. Such a distribution of bending rigidity of the non-expandable portion 322 can be obtained by bonding the coil 32 to the main body 11 only at the bonded portion 322a of the non-expandable portion 322. As a result, for example, when the medical device 2 is inserted into a portion of the lead 80 that has a large degree of curvature, the non-bonded portion 322b bends along the curvature of the lead 80, improving the passability of the medical device 2.

[0103] The X-ray transmittance of the non-expansion portion 322 may be smaller than the X-ray transmittance of the expansion portion 321. Specifically, for example, a portion containing an X-ray opaque material may be provided in at least a part of the non-expansion portion 322. This makes it possible to easily grasp the position of the non-expansion portion 322 of the expansion member 32 under X-ray fluoroscopy.

[0104] Examples of radiopaque materials include gold, platinum, tungsten, and alloys containing these elements.

[0105] The joining method of the joint 322a is not particularly limited. A solder material containing gold is used for the joint 322a of the medical device 2. The fourth portion 32D is fixed (joined) to the main body 11 by the solder material containing gold.

[0106] Examples of the solder material containing gold include gold, Au—Sn alloys, Au—Ge solder, Au—Si solder, Au—In solder, and Au—Sb solder, etc. As a result, the gold contained in the solder material of fourth portion 32D functions as an X-ray opaque material, and fourth portion 32D can be easily identified under X-ray fluoroscopy.

[0107] As described above, since the medical device 2 has the above-described configuration, the distal end of the expansion section 321 begins to expand radially outward before the proximal end of the expansion section 321. As a result, for example, when removing the hollow lead 80 from the body, the distal end of the expansion section 321 can be fixed distal to the lead 80, and the hollow lead 80 implanted in the body can be smoothly removed.

[0108] In the medical device 2, a non-expandable portion 322 (fourth portion 32D) is provided in the expansion member 32, and the non-expandable portion 322 has a non-bonded portion 322b. As a result, since the non-expandable portion 322 has the non-bonded portion 322b, the flexibility of the non-expandable portion 322 can be improved.

[0109] Fifth Embodiment Figure 28 is a schematic side view showing an enlarged portion of the fifth embodiment. As shown in Figure 28, the medical device 3 generally includes a main body 11, a distal fixation portion 21, an expansion member 31, a radiopaque marker 35, a push-in member 41, and a fixing mechanism 51 and a gripping member 61 (not shown). The fifth embodiment differs from the third embodiment in that it includes the radiopaque marker 35. The configurations of the main body 11, the distal fixation portion 21, the expansion member 31, the push-in member 41, the fixing mechanism 51, and the gripping member 61 are the same as those of the third embodiment. Therefore, the same components are denoted by the same reference numerals and detailed descriptions thereof will be omitted. The usage of the medical device 3 is the same as that of the medical device 1.

[0110] The radiopaque marker 35 is provided closer to the distal end than the first portion 31A, and is a member having a lower X-ray transmittance than other portions (e.g., the main body 11, the expansion member 31, etc.) of the medical device 3. The radiopaque marker 35 may be, for example, the distal fixing portion 21 containing a radiopaque brazing material, a coil formed of a radiopaque wire, or the like.

[0111] Examples of materials used for the radiopaque marker 35 include metal materials such as gold, platinum, tungsten, and lead, and materials containing these metal materials. The medical device 3 includes a coil (hereinafter also referred to as "coil 35") formed of a wire w4 containing platinum as the radiopaque marker 35. The tip of the coil 35 is connected to the main body 11 at the tip fixing portion 21, and the base end is joined to the tip of the coil 31.

[0112] As described above, the medical device 3 has the above-described configuration, and therefore the position of the distal end of the first portion 31A can be easily grasped under X-ray fluoroscopy.

[0113] [Sixth Embodiment] Figures 30 and 31 are schematic diagrams showing a sixth embodiment. As shown in Figures 30 and 31, the medical device 4 generally comprises a main body 14, a tip fixation section 21, an expansion member 31, a pushing member 41, a fixing mechanism 51, and a gripping member 61. The sixth embodiment differs from the third embodiment in that it comprises a main body 14. The configurations of the tip fixation section 21, the expansion member 31, the pushing member 41, the fixing mechanism 51, and the gripping member 61 are the same as those of the third embodiment. Therefore, the same parts are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0114] The main body 14 is an elongated member. The main body 14 of this embodiment is formed from the medical shaft described above in the section <Medical Shaft> (hereinafter also referred to as the "medical shaft 14"). The configuration of the medical shaft 14, other than the configuration of the medical shaft 14 described below, is the same as the configuration of the medical shaft 1001 described in the first embodiment.

[0115] The medical shaft 14 includes a first member 1014 and a second member 1021 .

[0116] The first member 1014 is an elongated member extending along the longitudinal direction. The first member 1014 is formed of a solid shaft body (hereinafter also referred to as the "shaft body 1014"). The first member 1014 has a first portion A51, a second portion A52, and a third portion A53. The second portion A52 is a portion provided closer to the base end than the first portion A51. The third portion A53 is a portion provided closer to the base end than the second portion A52.

[0117] In the medical device 4, the first portion A51 is formed of a large diameter portion 1411 whose diameter decreases toward the distal end. The second portion A52 is formed of a tapered portion 1421 tapering toward the proximal end, a small diameter portion 1422 having a constant outer diameter, and a tapered portion 1423 tapering toward the distal end. The third portion A53 is formed of a large diameter portion 1431 having a constant outer diameter. The outer diameter of the small diameter portion 1422 is smaller than the outer diameter of the shaft body 1014 other than the small diameter portion 1422.

[0118] The second portion A52 of the first member 1014 is provided on the proximal side of the expansion member 31. In this embodiment, the second portion A52 is provided between the expansion member 31 and the grip member 61.

[0119] The tensile breaking strength of the second portion A52 of the first member 1014, measured while applying tension in the longitudinal direction of the first member 1014, is smaller than the tensile breaking strength of the first portion A51 and also smaller than the tensile breaking strength of the third portion A53. In this embodiment, the outer diameter of the second portion A52 of the medical shaft 14 is the smallest (e.g., see FIG. 3 : D2min<D1min and D2min<D3min), and the tensile breaking strength of the second portion A52 is smaller than the tensile breaking strength of the shaft body 1014 other than the second portion A52. Therefore, of the shaft body 1014, the second portion A52 is most susceptible to breaking.

[0120] The second member 1021 is a member that extends along the longitudinal direction and covers a portion of the first member 1014. The second member 1021 is joined to the first member 1014 at a first portion A51 and a third portion A53.

[0121] In this embodiment, the second member is formed of a coil body 1021. The coil body 1021 is arranged to cover the outer periphery of the shaft body 1014. The coil body 1021 is joined to the first portion A51 and the third portion A53 of the shaft body 1014 at joints 1004a. The coil body 1021 is not joined to the second portion A52. The tensile breaking strength of the coil body 1021 is greater than the tensile breaking strength of the second portion A52 of the shaft body 1014.

[0122] A usage mode of the medical device 4 will be described. As described in the third embodiment, the medical device 4 is used, for example, to remove a hollow lead from inside the body, and the expansion member is inserted into the lumen of the lead and fixed to the lead by expanding radially outward. Here, an example is shown of a mode in which the lead 80 is removed after the expansion member 31 is fixed to the lead 80 inside the body in the third embodiment. The second portion A52 of the shaft body 1014 is usually exposed outside the body during the procedure so that fracture of the second portion A52 and the coil body 1021 can be visually confirmed.

[0123] After the expansion member 31 is fixed to the distal end of the lead 80, the operator pulls the medical device 4 toward the proximal end while grasping the grasping member 61. At this time, excessive load may be applied to the medical device 4 due to factors such as high friction between the lead 80 and body tissue. When excessive load is applied to the medical device 4 along the longitudinal direction, the second portion A52 of the shaft body 1014 breaks first, as shown in FIG. 32 . The operator can detect that excessive load is being applied to the medical device 4 by visually confirming the breakage of the second portion A52 or by sensing the impact at the time of breakage. Immediately after the shaft body 1014 breaks, the two portions of the broken first member 1014 (the portion including the first portion A51 and the portion including the third portion A53) remain connected via the coil body 1021. Therefore, the medical device 4 does not immediately disassemble, as shown in FIG. 33 .

[0124] When further load is applied to the medical device 4 in the longitudinal direction, the coil body 1021 stretches in the longitudinal direction. By checking the deformation of the coil body 1021, the operator can estimate the load applied to the medical device 4. When further load is applied to the medical device 4 in the longitudinal direction, the coil body 1021 breaks, as shown in Fig. 34. By visually confirming the breakage of the coil body 1021 or sensing the impact at the time of breakage, the operator can detect that further load is being applied and can take measures such as interrupting the procedure.

[0125] As described above, in the medical device 4, the second part A52 is provided closer to the proximal end than the expansion member 31. Therefore, for example, by disposing the second part A52 outside the body even during a procedure, the operator can easily detect excessive load by visual inspection, etc. As a result, the safety of the procedure can be further improved.

[0126] In this embodiment, the medical device 4 can be used to remove a hollow lead from the body, so that the lead placed in the body can be removed from the body more safely without applying excessive load to the medical device 4 or the lead.

[0127] In the above-described embodiment, the medical device 4 has been described in which the coil body 1021 and the gripping member 61 are provided separately. As shown in Fig. 35, the second member (e.g., the coil body 1027) and the gripping member 67 may be integrally formed. In such a case, the coil body 1027 and the gripping member 67 may be formed in part or entirely from a continuous wire w1007.

[0128] In the third to sixth embodiments described above, medical devices 1, 2, 3, and 4 were described in which the expansion members 31, 32 are expanded radially outward by compressing the expansion members 31, 32 along the longitudinal direction using a pushing member 41. The expansion members are not particularly limited as long as they cover the outer periphery of the main body and are expandable radially outward. For example, the medical device may use a self-expandable expansion member.

[0129] In the third to sixth embodiments described above, the expansion members 31, 32 are exemplified as coils 31, 32 wound with four single wires (wires w1) each having a circular cross section. The expansion members are not particularly limited as long as they cover the outer periphery of the main body and can be expanded radially outward. The expansion members may be other means than coils. When the expansion members are formed as coils, the shape and number of wires can be determined as appropriate.

[0130] The present disclosure is not limited to the configurations of the above-described embodiments, but is intended to include all modifications within the meaning and scope of the claims as defined by the claims. Part of the configurations of the above-described embodiments may be deleted or replaced with other configurations, or other configurations may be added to the configurations of the above-described embodiments.

[0131] The present disclosure includes the following configurations [1] to

[40] : [1] A medical device (1, 2, 3) comprising: an elongated main body (11); and an expansion member (31, 32) covering the outer periphery of the main body (11) and expandable radially outward, wherein the expansion member (31, 32) is a coil (31, 32) in which a wire (w1) is wound around the outer periphery of the main body (11), and a maximum width (a1) of the wire (w1) in a first portion (31A, 32A) of the coil (31, 32) is smaller than a maximum width (a2) of the wire (w1) in a second portion (31B, 32B) of the coil (31, 32) located closer to the base end than the first portion (31A, 32A). [2] The medical device (1, 2, 3) according to [1], wherein the maximum width of the wire (w1) gradually increases from the distal end to the proximal end of the coil (31, 32). [3] The medical device (1, 2, 3) according to [1] or [2], wherein the pitch (p1) of the wire (w1) in the first region (31A, 32A) is greater than the pitch (p2) of the wire (w1) in the second region (31B, 32B). [4] The medical device (1, 2, 3) according to any one of [1] to [3], wherein the coil (31, 32) has a third region (31C, 32C) located closer to the proximal end than the second region (31B, 32B), and wherein at least some of the wires (w1) among the adjacent wires (w1) are fixed to each other in the third region (31C, 32C). [5] The medical device (1, 2, 3) according to any one of [1] to [4], wherein the pitch of the wire (w1) gradually decreases from the distal end to the proximal end of the coil (31, 32). [6] The medical device (2) according to any one of [1] to [5], wherein the coil (32) has a fourth portion (32D) distal to the first portion (32A), and the fourth portion (32D) is fixed to the main body (11) with a solder material containing gold. [7] The medical device (3) according to any one of [1] to [6], wherein the medical device (3) has a radiopaque marker (35) distal to the first portion (31A, 32A).[8] The medical device (1, 2, 3) according to any one of [1] to [7], comprising a pushing member (41) movable along the longitudinal direction of the main body (11) and pushing the base ends of the expansion members (31, 32) toward the distal end, the pushing member (41) being a tubular body (41) that covers the outer periphery of the main body (11), and the maximum width of the pushing member (41) decreasing toward the distal end. [9] The medical device (1, 2, 3) according to [8], wherein the maximum width of the distal end of the pushing member (41) is smaller than the maximum width of the proximal end of the expansion members (31, 32).

[10] The medical device (1, 3) comprises an elongated main body (11) and an expansion member (31) that covers the outer periphery of the main body (11) and is expandable radially outward, the distal end of the expansion member (31) beginning to expand radially outward before the proximal end of the expansion member (31).

[11] The medical device (1, 3) according to

[10] , wherein, when the expansion member (31) is in an expanded state, the maximum width (D1) of the distal end of the expansion member (31) is greater than the maximum width (D3) of the proximal end of the expansion member (31).

[12] The medical device (1, 3) according to

[10] or

[11] , wherein the expansion force of the distal end of the expansion member (31) is greater than the expansion force of the proximal end of the expansion member (31).

[13] The medical device (1, 3) according to any one of

[10] to

[12] , wherein the stress generated in the distal end of the expansion member (31) due to longitudinal compression of the expansion member (31) is greater than the stress generated in the proximal end of the expansion member (31) due to longitudinal compression of the expansion member (31).

[14] The medical device (1, 3) according to any one of

[10] to

[13] , further comprising a pushing member (41) movable along the longitudinal direction of the main body (11) and pushing the proximal end of the expansion member (31) toward the distal end.

[15] The medical device (1, 3) according to any one of

[10] to

[14] , wherein the expansion member (31) is a coil (31) in which a wire (w1) is wound around the outer periphery of the main body (11).

[16] The medical device (1, 3) according to

[15] , wherein the pitch of the wire (w1) at the distal end of the coil (31) is greater than the pitch of the wire (w1) at the proximal end of the coil (31).

[17] The medical device (1, 3) according to

[15] or

[16] , wherein the maximum width of the wire (w1) at the distal end of the coil (31) is smaller than the maximum width of the wire (w1) at the proximal end of the coil (31).

[18] The medical device (1, 3) according to any one of

[10] to

[17] , wherein the expansion member (31) is used to remove a hollow lead (80) from the body, and the expansion member (31) is inserted into the lumen of the lead (80), expands radially outward, and is fixed to the lead (80).

[19] The medical device (1, 3) described in

[18] , wherein the lead (80) has a first electrode (81) located at the tip of the lead (80) and a second electrode (82) located proximal to the first electrode (81), and when the expansion member (31) is in an expanded state, the outer periphery of the expansion member (31) abuts against the inner periphery of a portion of the lead (80) distal to the second electrode (82).

[20] The medical device (1, 3) described in any one of

[10] to

[19] , wherein the tip of the expansion member (31) is located within 10 mm of the tip of the main body (11) proximal to the main body (11) in the longitudinal direction.

[21] A medical device (2) comprising: an elongated main body (11); and an expansion member (32) covering the outer periphery of the main body (11) and expandable radially outward, the expansion member (32) having an expansion section (321) expandable radially outward, and a non-expandable section (322) provided distally of the expansion section (321) and not expandable radially outward, wherein the distal end of the non-expandable section (322) and the proximal end of the non-expandable section (322) are fixed to the main body (11) at joint sections (322a), and a portion of the non-expandable section (322) between the distal end of the non-expandable section (322) and the proximal end of the non-expandable section (322) is a non-joint section (322b) that is not fixed to the main body (11).

[22] The medical device (2) according to

[21] , wherein the bending stiffness of the non-bonded portion (322b) is smaller than the bending stiffness of any of the bonded portions (322a).

[23] The medical device (2) according to

[21] or

[22] , wherein the expansion member (32) is a coil (32) in which a wire (w1) is wound around the outer periphery of the main body (11).

[24] The medical device (2) according to any one of

[21] to

[23] , wherein the X-ray transmittance of the non-expandable portion (322) is lower than the X-ray transmittance of the expansion portion (321).

[25] A medical device (1, 2, 3) comprising: an elongated main body (11); expansion members (31, 32) covering the outer periphery of the main body (11) and expandable radially outward; and a pushing member (41) movable along the longitudinal direction of the main body (11) and pushing the proximal ends of the expansion members (31, 32) toward the distal end, wherein the rigidity of the proximal end of the pushing member (41) is greater than the rigidity of the distal end of the pushing member (41).

[26] The medical device (1, 2, 3) according to

[25] , wherein the pushing member (41) has a reinforcing coil (411) covering the outer periphery of the proximal end of the pushing member (41).

[27] The medical device (1, 2, 3) according to

[26] , wherein the proximal end of the pushing member (41) is provided with a pushing loop member (412), and the proximal end of the pushing loop member (412) is fixed between the outer periphery of the proximal end of the pushing member (41) and the inner periphery of the reinforcing coil (411).

[28] The medical device (1, 2, 3) according to

[27] , wherein the maximum width (s1) of the pushing loop member (412) is smaller than the maximum width (s2) of the reinforcing coil (411).

[29] A medical device (1, 2, 3) comprising: an elongated main body (11); expansion members (31, 32) covering the outer periphery of the main body (11) and expandable radially outward; a pushing member (41) movable along the longitudinal direction of the main body (11) and pushing the base ends of the expansion members (31, 32) toward the distal end; and a fixing mechanism (51) capable of fixing the main body (11) and the pushing member (41), wherein the pushing member (41) is a tubular body (41) covering the outer periphery of the main body (11), and the fixing mechanism (51) fixes the main body (11) to the pushing member (41) by engaging the outer periphery of the main body (11) with the inner periphery of the pushing member (41).

[30] The medical device (1, 2, 3) according to

[29] , wherein the main body (11) is a core shaft (11), the fixing mechanism (51) has a curved portion (113) formed by bending a portion of the core shaft (11), and the curved portion (113) abuts against the inner circumference of the pushing member (41).

[31] The medical device (1, 2, 3) according to

[30] , wherein the fixing mechanism (51) has a first curved portion (113A) formed by bending the core shaft (11) in a first direction, and a second curved portion (113B) formed by bending the core shaft (11) in a second direction different from the first direction.

[32] The medical device (1, 2, 3) according to

[31] , wherein the first curved portion (113A) and the second curved portion (113B) of the fixing mechanism (51) are arranged in a zigzag pattern.

[33] The medical device (1, 2, 3) according to any one of

[29] to

[32] , wherein the main body (11) has a first marker (511) at a position distal to the tip of the fixing mechanism (51).

[34] The medical device (1, 2, 3) according to

[33] , wherein the main body (11) has a second marker (512) at a position proximal to the base end of the fixing mechanism (51).

[35] The medical device (1, 2, 3) according to

[34] , wherein the first marker (511) and the second marker (512) are each a metal oxide coating formed on the surface of the main body (11).

[36] The medical device (1, 2, 3) according to any one of

[29] to

[35] , wherein a position marker (413) is provided on the outer periphery of the proximal end of the pushing member (41).

[37] A medical device (1, 2, 3) comprising: an elongated main body (11); expansion members (31, 32) covering the outer periphery of the main body (11) and expandable radially outward; a pushing member (41) movable along the longitudinal direction of the main body (11) and pushing the base ends of the expansion members (31, 32) toward the distal end; and a flexible gripping member (61) arranged proximal to the pushing member (41) and connected to the base end of the main body (11), wherein the gripping member (61) is formed by spirally winding a wire (w1).

[38] The medical device (1, 2, 3) according to

[37] , wherein the length of the gripping member (61) in the longitudinal direction is greater than the length of the pushing member (41) in the longitudinal direction.

[39] The medical device (1, 2, 3) according to

[37] or

[38] , wherein the gripping member (61) is tubular, and a gripping loop member (611) is provided at the base end of the gripping member (61), and the tip end of the gripping loop member (611) is fixed to the inner circumference of the base end of the tubular gripping member (61).

[40] The medical device (1, 2, 3) according to

[39] , wherein the maximum width (b1) of the gripping loop member (611) is smaller than the maximum width (b2) of the gripping member (61).

Claims

1. A medical shaft (1001, 1002) comprising a first member (1011) extending along its longitudinal axis, wherein the first member (1011) has a first portion (A11), second portions (A12, A22, A32, A42) provided on the proximal side of the first portion (A11), and a third portion (A13) provided on the proximal side of the second portions (A12, A22, A32, A42), and wherein the tensile breaking strength of the second portions (A12, A22, A32, A42) of the first member (1011), measured while applying tension in the longitudinal direction of the first member (1011), is smaller than the tensile breaking strength of the first portion (A11) and is also smaller than the tensile breaking strength of the third portion (A13).

2. A medical shaft (1001) as described in claim 1, comprising a second member (1021) covering a portion of the first member (1011) and extending along the longitudinal axis direction, the second member (1021) being joined to the first member (1011) at the first portion (A11) and the third portion (A13), and the second member (1021) being a coil body (1021).

3. A medical shaft (1002) as described in claim 1, comprising a second member (1022) covering a portion of the first member (1011) and extending along the longitudinal axis direction, the second member (1022) being joined to the first member (1011) at the first portion (A11) and the third portion (A13), and the second member (1022) being a braided body (1022).

4. A medical shaft (1001, 1002) as described in claim 1, comprising a second member (1021, 1022) covering a portion of the first member (1011) and extending along the longitudinal axis direction, the second member (1021, 1022) being joined to the first member (1011) at the first portion (A11) and the third portion (A13), and the tensile breaking strength of the second member (1021, 1022), measured with tension applied in the longitudinal axis direction, is greater than the tensile breaking strength of the second portion (A12) of the first member (1011).

5. A medical shaft (1001, 1002) described in any one of claims 1 to 4, wherein the outer diameter of the second portion (A12) of the first member (1011) is smaller than the outer diameter of the first portion (11) and smaller than the outer diameter of the third portion (A13).

6. A medical device (4) comprising an elongated main body (14) and an expansion member (31) covering the outer periphery of the distal end of the main body (14) and expandable radially outward, wherein the main body (14) is a medical shaft (14) as defined in any one of claims 1 to 5, and the second portion (A52) of the first member (14) is located closer to the base end than the expansion member (31).

7. A medical device (4) as described in claim 6, further comprising a gripping member (61, 67) disposed proximally of the expansion member (31) and connected to the proximal end of the main body (14), wherein the second portion (A52) of the first member (14) is provided between the expansion member (31) and the gripping member (61, 67).

8. A medical device (4) as described in claim 6 or claim 7, which is used to remove a hollow lead (80) from the body, and the expansion member (31) is inserted into the inner cavity (80h) of the lead (80) and fixed to the lead (80) by expanding the expansion member (31) radially outward.

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