catheter

Abstract

The present invention provides a catheter with a hollow shaft, wherein the front end portion of the hollow shaft has: a first section, which extends in a roughly linear shape; and a second section, which is arranged on the front end side of the first section and includes a first bend and a second bend formed at a position closer to the front end side than the first bend. When an imaginary plane located on the axis of the hollow shaft constituting the first section is used as a boundary, the area defined by one side of the imaginary plane is set as the first area, and the area defined by the other side is set as the second area, the first bend and the front end of the catheter are located in the first area, and the second bend is located in the second area. The distance from the front end of the catheter to the imaginary plane is greater than the distance from the first bend to the imaginary plane, and the rigidity of the first bend is greater than the rigidity of the second bend.

Description

Technical Field

[0001] The present invention relates to a catheter. Background Art

[0002] Conventionally, there is known a catheter having a hollow shaft with a distal end portion formed in a curved shape (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-87389. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, even based on the above-mentioned conventional technologies, there is still room for improvement in the technology for improving the performance (selectivity) of advancing a catheter toward a target within an internal organ or blood vessel with complex branches.

[0008] An object of the present invention is to improve the performance (selectivity) of advancing a catheter toward a target direction within an internal organ or blood vessel with complex branching in the body.

[0009] Means of solving problems

[0010] The present invention has been made to solve at least a part of the above-mentioned problems, and can be implemented as follows.

[0011] According to one aspect of the present invention, a catheter is provided. The present invention provides a catheter having a hollow shaft, wherein the distal end of the hollow shaft comprises: a first section extending substantially linearly; a second section connected to the distal end of the first section and forming a first bend; and a third section connected to the distal end of the second section and forming a second bend. The second section has a greater rigidity than the third section. When an imaginary plane is defined along the axis of the first section, with a spatial region on one side of the imaginary plane being the first region and a spatial region on the other side being the second region, the first bend and the distal end of the catheter are located in the first region, and the second bend is located in the second region. The distance from the distal end of the catheter to the imaginary plane is greater than the distance from the first bend to the imaginary plane.

[0012] With this structure, the force applied in the axial direction of the catheter, such as the force pushing the catheter forward, is converted toward the distal end of the catheter via the first and second bends. This facilitates the catheter's movement toward the distal end. Furthermore, because the distance from the distal end of the catheter to the imaginary plane is greater than the distance from the first bend to the imaginary plane, insertion of the distal end of the catheter into the bifurcation of the blood vessel is facilitated when the distal end reaches the bifurcation. Furthermore, by making the rigidity of the second section greater than that of the third section, the likelihood of the distal end of the catheter being pushed back to the rear end of the catheter can be reduced.

[0013] In the above-described catheter, the rigidity of the first section of the hollow shaft can be greater than that of the second section. This configuration allows the force for pushing the catheter or rotating the catheter to be more reliably transmitted from the rear end of the catheter to the front end.

[0014] In the catheter of the above aspect, when the catheter is viewed from the front, the front end of the first section of the hollow shaft, the front end of the first curved portion, and the front end of the second curved portion are arranged on a straight line.

[0015] When viewing the catheter from the front, the distal end of the first section, the apex of the first bend, and the apex of the second bend may also be arranged on a straight line. This configuration reduces the likelihood of force being generated in a direction orthogonal to the catheter axis, compared to a case where the distal end of the first section, the apex of the first bend, and the apex of the second bend are not arranged on a straight line. This reduces the likelihood of the distal end of the catheter rotating in a direction unintended by the user.

[0016] Furthermore, the present invention can be implemented in various forms, for example, in the form of a guide wire, a method for manufacturing a guide wire, a method for manufacturing a catheter, an endoscope, a dilator, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an explanatory diagram illustrating the overall structure of the catheter according to the first embodiment.

[0018] Figure 2 It is an explanatory diagram illustrating the bending portion of the catheter according to the first embodiment.

[0019] Figure 3 This is an explanatory diagram illustrating the catheter according to the first embodiment when viewed from the front.

[0020] Figure 4 This is a first explanatory diagram illustrating a state where a catheter is used within a blood vessel.

[0021] Figure 5 This is a second explanatory diagram illustrating a state where the catheter is used within a blood vessel.

[0022] Figure 6This is an explanatory diagram illustrating the overall structure of a catheter according to the second embodiment. DETAILED DESCRIPTION

[0023] <First embodiment>

[0024] Figure 1 1 is an explanatory diagram illustrating the overall structure of the catheter 1 according to the first embodiment. Figure 1 This section includes a portion that describes the relative size of each component in a different relative ratio than the actual size. Figures 2 to 6 The same applies to the various explanatory drawings shown.

[0025] exist Figure 1 In the figure, the left side is the front end side of the catheter 1 and its components, and the right side is the rear end side of the catheter 1 and its components. The front end side of the catheter 1 is the side inserted into the body (distal side), and the base end side of the catheter 1 is the side operated by a doctor or other operator (proximal side). Figure 1 The left-right direction is referred to as the axial direction of the duct 1 and each component. The direction perpendicular to the axial direction is referred to as the radial direction of the duct 1 and each component.

[0026] Furthermore, the end portion of the catheter 1 and each component of the catheter 1 located on the front side is referred to as the "front end," and the portion extending from the front end toward the rear end, including the "front end," is referred to as the "front end portion." Similarly, the end portion of the catheter 1 and each component of the catheter 1 located on the rear side is referred to as the "rear end," and the portion extending from the rear end toward the front end, including the "rear end," is referred to as the "rear end portion."

[0027] The catheter 1 is a medical device that is inserted into a blood vessel or a digestive organ for treatment or examination. The catheter 1 includes a hollow shaft 10 , a distal tip 60 , and a grip 70 .

[0028] The hollow shaft 10 is a long, tubular body extending along the axis of the catheter 1. It is formed from a flexible resin. The distal end of the hollow shaft 10 has a curved shape. The grip 70 is connected to the rear end of the hollow shaft 10, and the distal tip 60 is connected to the distal end of the hollow shaft 10. The lumen (inner cavity) of the hollow shaft 10 communicates with the lumens of the grip 70 and the distal tip 60.

[0029] The front tip 60 is a tubular member connected to the front end of the hollow shaft 10. It constitutes the distal end of the catheter 1 and serves to reduce the risk of the catheter 1 damaging the body. The front tip 60 can be formed from a flexible resin material. For example, TPU (thermoplastic polyurethane) can be selected. The front tip 60 is not limited to resin materials and can also be formed from metal.

[0030] The gripping portion 70 is a tubular body connected to the rear end of the hollow shaft 10. A surgeon, such as a doctor, grips the gripping portion 70 to operate the catheter 1. The gripping portion 70 includes a protector 71, a main body 72, and a connector 73. The protector 71 has a tapered shape that increases in diameter toward the rear end of the protector 71. To facilitate gripping by a surgeon, such as a doctor, the main body 72 has a protrusion on the outer periphery. The connector 73 has a threaded process on the inner periphery, for example, so that it can be connected to other medical equipment such as a syringe (not shown). The gripping portion 70 is durable and can be formed of a material suitable for sterilization. For example, it can be metal, injection-molded resin, or a combination thereof.

[0031] The hollow shaft 10 includes a first hollow shaft 11, a second hollow shaft 12, and a third hollow shaft 13. The base end of the first hollow shaft 11 is connected to the grip 70, and the front end is connected to the second hollow shaft 12. The base end of the second hollow shaft 12 is connected to the front end of the first hollow shaft 11, and the front end is connected to the third hollow shaft 13. The base end of the third hollow shaft 13 is connected to the front end of the second hollow shaft 12, and the front end is connected to the front end tip 60. The connection portion between the front end of the first hollow shaft 11 and the rear end of the second hollow shaft 12 is defined as a connection portion 14 between the first hollow shaft 11 and the second hollow shaft 12. The connection portion 14 is provided on a linear portion of the hollow shaft 10. In other words, the connection portion 14 is provided on the axis of the first hollow shaft 11. The connection portion between the front end of the second hollow shaft 12 and the rear end of the third hollow shaft 13 is defined as a connection portion 15 between the second hollow shaft 12 and the third hollow shaft 13. The first hollow shaft 11 is generally linear and is formed approximately parallel to the axis of the catheter 1. At least a portion of the second hollow shaft 12 has a curved portion. At least a portion of the third hollow shaft 13 has a curved portion. The first, second, and third hollow shafts 11, 12, and 13 are continuously connected and have a lumen (not shown) connecting them. This lumen is used for the insertion of other instruments such as guidewires and for the delivery of medical solutions.

[0032] In this embodiment, the substantially linear section formed by the first hollow shaft 11 in the hollow shaft 10 is referred to as the first section 21, the section formed by the second hollow shaft 12, which includes both a substantially linear portion and a curved portion, is referred to as the second section 22, and the section formed by the third hollow shaft 13, which includes the curved portion, is referred to as the third section 23. The length of the first section is longer than the second and third sections. Furthermore, the length of the first section is longer than the sum of the lengths of the second and third sections.

[0033] The stiffness of the first interval 21 is greater than the stiffness of the second interval 22. In addition, the stiffness of the second interval 22 is greater than the stiffness of the third interval 23. In the present embodiment, the stiffness of the first hollow shaft 11 is greater than the stiffness of the second hollow shaft 12, and the stiffness of the second hollow shaft 12 is greater than the stiffness of the third hollow shaft 13. In other words, the stiffness of the hollow shaft 10 decreases in stages from the rear end side toward the front end side. Thus, the catheter 1 has a structure in which the flexibility increases toward the front end direction of the catheter 1. For example, it is preferred to set the ratio of the stiffness of each interval when the stiffness of the third interval 23 is set to 1 to be: third interval 23: second interval 22: first interval 21 = 1:10~20:30~300. It is preferred to set the stiffness value of each interval in this case to: 0.005 ~0.050gf·cm for the third interval 23 2 / cm, and the second interval 22 is 0.050 ~ 1.00gf·cm 2 / cm, the first interval 21 is 0.150 ~15.0gf·cm 2 / cm. By designing the stiffness of each section in this way, the catheter 1 can achieve both pushability and distal flexibility. Specifically, the inventors discovered that, in a hollow shaft 10 having a first bend 31 and a second bend 32, described below, and with first, second, and third distances L1, L2, and L3 meeting the conditions described below, by setting the stiffness of the first, second, and third sections within the aforementioned range, both pushability and distal flexibility can be fully achieved.

[0034] A plane located on the axis of the first hollow shaft 11 and extending toward the distal end of the catheter 1 is defined as a virtual plane 40 . Figure 1 The imaginary plane 40 shown in FIG. shows a longitudinal cross section of the imaginary plane 40. The spatial region defined by the imaginary plane 40 and extending toward one side of the imaginary plane 40 is referred to as a first region 51, and the spatial region extending toward the other side of the imaginary plane 40 is referred to as a second region 52. The first region 51 and the second region 52 face each other with the imaginary plane 40 as the boundary.

[0035] The portion of the curved shape formed by the second hollow shaft 12 is referred to as the first curved portion 31. In the second section 22, the first curved portion 31 is located within the first region 51. The portion of the curved shape formed by the third hollow shaft 13 is referred to as the second curved portion 32. In the third section 23, the second curved portion 32 is located within the second region 52. The connecting portion 15 between the second hollow shaft 12 and the third hollow shaft 13 is located between the first curved portion 31 and the second curved portion 32.

[0036] Figure 2 It is an explanatory diagram illustrating the bending portion of the catheter 1 according to the first embodiment.

[0037] The portion with the greatest curvature within the curved shape of the second hollow shaft 12 is designated as the maximum curved portion Rmax1. The center of the radius of curvature Rc1 of the maximum curved portion Rmax1 is designated as the center C1 of the maximum curved portion Rmax1. The first curved portion 31 within the second hollow shaft 12 is defined as the portion within an arc A1 extending from the center C1 of the maximum curved portion Rmax1 toward the outside of the curved shape, with the radius of curvature Rc1 of the maximum curved portion Rmax1 as the centerline, and with a center angle α1 of 60 degrees. The portion with the greatest curvature within the curved shape of the third hollow shaft 13 is designated as the maximum curved portion Rmax2. The center of the radius of curvature Rc2 of the maximum curved portion Rmax2 is designated as the center C2 of the maximum curved portion Rmax2. The second curved portion 32 within the third hollow shaft 13 is defined as the portion within an arc A2 extending from the center C2 of the maximum curved portion Rmax2 toward the outside of the curved shape, with the radius of curvature Rc2 of the maximum curved portion Rmax2 as the centerline, and with a center angle α2 of 60 degrees. The first curved portion 31 and the second curved portion 32 have been shaded in the respective drawings.

[0038] In the first bend 31, the point farthest from the imaginary plane 40 is set as the vertex p1 of the first bend. The distance from the vertex p1 of the first bend to the imaginary plane 40 is set as the first distance L1. In the second bend 32, the point farthest from the imaginary plane 40 is set as the vertex p2 of the second bend. The distance from the vertex p2 of the second bend to the imaginary plane 40 is set as the second distance L2. At the front end of the catheter 1 (the front end of the front tip 60), the distance from the point farthest from the imaginary plane 40 to the imaginary plane 40 is set as the third distance L3. The second distance L2 of the catheter 1 is greater than the first distance L1. Therefore, as shown in FIG. Figure 4 As shown, when the front end (front end tip 60) of the catheter 1 is tilted toward the base end side of the catheter 1 in the blood vessel, the second distance L2 is reduced, and the first distance L1 and the second distance L2 become approximately equal. As a result, the force when pushing the base end side of the catheter 1 passes near the center of gravity of the front end side of the catheter 1, which can improve the propulsion performance. In addition, if the first distance L1 is greater than the second distance L2, the length of the first bend 31 becomes relatively larger at the front end of the catheter 1. In this case, the force when pushing the base end side of the catheter 1 is absorbed by the first bend 31 due to the bending of the first bend 31. By making the first distance L1 smaller than the second distance L2, the attenuation rate of the force when pushing the base end side of the catheter 1 reaching the front end of the catheter 1 can be reduced. The third distance L3 of the catheter 1 is greater than the first distance L1. Thus, as Figure 4 As shown in FIG. 1 , the front end (front end tip 60) of the catheter 1 can be easily tilted toward the base end of the catheter 1 in the blood vessel. In addition, the third distance L3 of the catheter 1 is greater than the second distance L2. Figure 4As shown, when the distal end (distal tip 60) of the catheter 1 is tilted toward the proximal end of the catheter 1 within a blood vessel, the decrease in the third distance L3 is greater than the decrease in the second distance L2, and the second distance L2 and the third distance L3 are approximately equal. This allows the force applied to the proximal end of the catheter 1 to pass near the center of gravity of the distal end of the catheter 1, thereby improving propulsivity. Furthermore, if the first distance L1 is greater than the third distance L3, the length of the first bend 31 becomes relatively longer at the distal end of the catheter 1. In this case, the force applied to the proximal end of the catheter 1 is absorbed by the bending of the first bend 31. By making the first distance L1 smaller than the third distance L3, the attenuation rate of the force applied to the proximal end of the catheter 1 reaching the distal end of the catheter 1 can be reduced. For example, assuming the stiffness of the first distance L1 is 1, the ratio of the respective distances can be set to 1:5-10:6-16 for the first distance L1:second distance L2:third distance L3. In this case, the first distance L1 may be set to 0.500 mm to 3.00 mm, the second distance L2 may be set to 2.50 mm to 5.00 mm, and the third distance L3 may be set to 3.00 mm to 8.00 mm.

[0039] The maximum bend Rmax2 of the second bend is located at a position closer to the distal end than the vertex p2 of the second bend in the axial direction of the catheter 1. As a result, since the distal end (the distal tip 60) of the catheter 1 is slightly inclined toward the proximal end of the catheter 1, Figure 4 In the blood vessel shown, the distal end of the catheter 1 can be tilted toward the proximal end more easily.

[0040] The maximum curvature of the second curved portion 32 is greater than that of the first curved portion 31. In other words, the maximum curvature of the curved portion at the front end is greater than that at the rear end. As a result, the front end of the catheter 1 is curved toward the rear end.

[0041] The rigidity of the first curved portion 31 is greater than that of the second curved portion 32. In other words, the rigidity of the curved portion on the rear end side is greater than that of the curved portion on the front end side. This prevents deformation of the first curved portion 31 when the distal end (distal tip 60) of the catheter 1 is tilted toward the proximal end of the catheter 1, making it easier to tilt the distal end of the catheter 1 toward the proximal end. Furthermore, the attenuation rate of the force applied to the proximal end of the catheter 1 in the first curved portion 31 can be reduced.

[0042] Figure 3 This is an explanatory diagram illustrating the front view of the catheter according to the first embodiment. Figure 3 In FIG, the cross-sectional outline of the front end portion of the first section 21 , the cross-sectional outline of the first curved portion 31 including the vertex p1 , and the cross-sectional outline of the second curved portion 32 including the vertex p2 are indicated by dotted lines.

[0043] The front end of the first section 21 of the first hollow shaft 11, the vertex p1 of the first curved portion 31, the vertex p2 of the second curved portion 32, and the front end tip 60 are located on a straight imaginary line 41. It should be noted that the straight mentioned here includes not only completely straight but also approximately straight. For example, Figure 3 In the embodiment, when viewed from the front, if the angle formed by the straight line connecting the front end tip 60 and the vertex p2 of the second curved portion 32 and the straight line connecting the vertex p2 of the second curved portion 32 and the vertex p1 of the first curved portion 31 is less than 10°, it can be said that they are located on a straight line.

[0044] The hollow shaft 10 preferably has anti-thrombotic properties, flexibility, and biocompatibility, and can be formed of, for example, a resin material such as polyamide resin, polyolefin resin, polyester resin, polyurethane resin, silicone resin, or fluororesin. The outer diameter, inner diameter, and length of the hollow shaft 10 can be arbitrarily determined.

[0045] Figure 4 This is a first explanatory diagram illustrating a state where the catheter 1 is used within a blood vessel.

[0046] exist Figure 4 In the embodiment, the catheter 1 is inserted into the blood vessel 100. The surgeon or other operator pushes the catheter 1 in the blood vessel toward the target site such as the lesion to be treated. Figure 3 As shown, when the inner diameter of the blood vessel 100 is smaller than the distance between the first and second bends 31, 32 of the catheter 1, both the first and second bends 31, 32 advance while in contact with the blood vessel wall 102. Therefore, the catheter 1 advances while applying radial force to the blood vessel 100, using the first and second bends 31, 32 as contact points. In other words, the catheter 1 advances within the blood vessel 100 while pushing and expanding the blood vessel wall 102. A surgeon or other operator may sometimes advance the catheter 1 into a branch vessel 101. In such cases, the surgeon pushes, pulls, or rotates the catheter 1 to insert the distal end of the catheter 1 into the branch vessel 101.

[0047] <Effects of the First Embodiment>

[0048] Figure 5 This is a second explanatory diagram illustrating the state in which the catheter 1 is used within a blood vessel.

[0049] Figure 5 The distal end of the catheter 1 is shown inserted into the branch vessel 101. When the target lesion is located at the distal end of the branch vessel 101, the operator, such as a doctor, confirms that the distal end of the catheter 1 is inserted into the branch vessel 101 and then advances the catheter 1 into the branch vessel 101.

[0050] When the catheter 1 is transported toward the branch of the blood vessel, the front end of the catheter 1, which was pressed against the blood vessel wall 102, is released, and the front end of the catheter 1 tends to return to its original curved shape. As a result, the front end of the catheter 1 enters the branch vessel 101. Therefore, it is easy for a doctor or other operator to advance the catheter 1 toward the branch vessel 101. Furthermore, the force 120 applied axially to the catheter 1 by the doctor or other operator pushing the catheter 1 is transmitted to the front end of the catheter 1 via the first curved portion 31 and the second curved portion 32. At this time, because the first curved portion 31 and the second curved portion 32 are supported by the blood vessel wall 102, the force 120 is converted from an axial force of the catheter 1 to a force in the distal direction. This makes it easier to advance the front end of the catheter 1 into the branch vessel 101.

[0051] The catheter 1 advances while pressing against the dilated blood vessel 100. Consequently, when a force is applied to the catheter 1 in the direction opposite to its travel direction, resistance (the backup force of the catheter 1) acts to prevent the catheter 1 from being pushed back, thereby reducing the likelihood of the catheter 1 being pushed back. Furthermore, the rigidity of the first curved portion 31 is greater than that of the second curved portion 32. This creates a backup force for the catheter 1 in the first curved portion 31, further reducing the likelihood of the catheter 1 being pushed back in the direction opposite to its travel direction.

[0052] The length of the first section is longer than the second and third sections. This allows the catheter 1 to be pushed back even when a medical solution is injected into the lumen of the catheter 1 and then released from the distal end of the catheter 1. The resistance (supporting performance of the catheter 1) that prevents the catheter 1 from being pushed back is fully utilized, thereby reducing the possibility of the catheter 1 being pushed back. Furthermore, the length of the first section is longer than the sum of the lengths of the second and third sections. This further improves the supporting performance of the catheter 1.

[0053] The rigidity of the first section 21 is greater than that of the second section 22. This allows for more reliable transmission of forces such as those pushing and rotating the catheter 1 from the rear end of the catheter 1 to the front end. This makes it easier for doctors and other operators to manipulate the catheter 1. Furthermore, the rigidity decreases in the order of the first hollow shaft 11, the second hollow shaft 12, and the third hollow shaft 13. This increases the flexibility of the catheter 1 toward the front end, making it easier to adapt to the complex curves of internal organs and blood vessels.

[0054] The connection portion 14 between the first hollow shaft 11 and the second hollow shaft 12 is provided in a straight portion of the hollow shaft 10. When the connection portion 14 is provided in a curved portion, it is possible to suppress smooth deformation of the curved portion. Providing the connection portion 14 in a straight portion can reduce the possibility of suppressing deformation of the curved portion.

[0055] The connecting portion 15 between the second hollow shaft 12 and the third hollow shaft 13 is provided between the first curved portion 31 and the second curved portion 32. When the connecting portion 15 is provided in the curved portion, it is possible to suppress smooth deformation of the curved portion. Providing the connecting portion 15 in a straight portion can reduce the possibility of suppressing deformation of the curved portion.

[0056] The third distance L3 is greater than the first distance L1. In other words, the distal end of the catheter 1 is located radially outward of the apex p1 of the first bend 31. As a result, when the catheter 1 reaches the branch vessel 101, the distal end of the catheter 1 can be smoothly inserted into the entrance of the branch vessel 101.

[0057] The maximum bend Rmax2 of the second bend is located closer to the distal end than the apex p2 of the second bend in the axial direction of the catheter 1. This reduces the likelihood of resistance to a force applied in the direction of advancement of the catheter 1 by an operator, such as a physician, when the catheter 1 advances within the blood vessel 100, thereby facilitating advancement of the catheter 1 within the blood vessel.

[0058] The curvature of the second curved portion 32 is greater than that of the first curved portion 31. As a result, the front end of the catheter 1 is bent toward the rear end of the catheter 1. Therefore, it is easy to make the front end of the catheter 1 Figure 4 、 5 The catheter 1 is shown traveling in a branch vessel 101 extending in a direction opposite to the traveling direction of the catheter 1 .

[0059] like Figure 3 As shown, the first hollow shaft 11, the first curved portion 31, and the second curved portion 32 are located on a straight imaginary line 41. This reduces the likelihood of forces being generated in a direction perpendicular to the axial direction of the catheter 1, compared to a case where the first hollow shaft 11, the first curved portion 31, and the second curved portion 32 are not arranged on the same axis. Consequently, the possibility of the distal end of the catheter 1 rotating in a direction unintended by the user is reduced.

[0060] <Second embodiment>

[0061] Figure 6 This is an explanatory diagram illustrating the overall structure of a catheter according to the second embodiment.

[0062] The catheter 2 of the second embodiment differs from the catheter 1 of the first embodiment only in that the first section 21 and the second section 22 are formed by the first hollow shaft 11, which is connected to the third hollow shaft 13. The remaining parts are identical to the structure of the catheter 1, and thus their description is omitted.

[0063] In the catheter 2, the first hollow shaft 11 includes a portion extending approximately linearly from the rear end of the catheter 2 toward the front end of the catheter 2 and a first curved portion 31. The front end of the first hollow shaft 11 is connected to the third hollow shaft 13. The rear end of the third hollow shaft 13 is connected to the first hollow shaft 11. In other words, the front end of the catheter 2 is composed of two hollow shafts. The first section 21 is defined by the linear portion of the first hollow shaft 11. The second section 22 is defined by a portion including the linear portion of the first hollow shaft 11 and the first curved portion 31. The portion connecting the front end of the first hollow shaft 11 and the rear end of the third hollow shaft 13 is defined as the connecting portion 14a between the first hollow shaft 11 and the third hollow shaft 13. The connecting portion 14a is located between the first curved portion 31 and the second curved portion 32.

[0064] <Effects of the Second Embodiment>

[0065] In addition to the effects of the catheter 1 of the first embodiment, the catheter 2 can further reduce the number of hollow shafts constituting the distal end of the catheter 2 to avoid stress concentration at the connection between the hollow shafts and reduce the possibility of kinking.

[0066] <Modification of the embodiment>

[0067] The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit and scope of the present invention. For example, the following modifications are also possible.

[0068] [Variation 1]

[0069] The catheter 1 of the first embodiment may also be formed by a multilayer tube formed by radially overlapping multiple resin tubes. In this case, the catheter 1 may also include a reinforcement such as a braid or coil formed of metal wire between the multiple resin layers. The catheter 1 may also have multiple lumens. In this case, one lumen can be used to pass through and insert a combined instrument such as a guidewire, while another lumen can be used to transport liquids such as liquid medicine. Furthermore, the catheter 1 may not have the front end tip 60 or the grip 70.

[0070] [Variation 2]

[0071] The hollow shaft 10 of the catheter 1 of the first embodiment can also be formed from a single resin tube. In this case, the rear end of the single resin tube is formed straight, with the first bend 31 and the second bend 32 provided at the front end. The hollow shaft 10 can also be formed by connecting an unlimited number of resin tubes. In this case, the first bend 31 and the second bend 32 are provided on the resin tube located at the front end of the multiple resin tubes.

[0072] [Variation 3]

[0073] The first section 21 and the second section 22 of the catheter 1 of the first embodiment may have a bend further rearward than the first bend 31. In other words, the catheter 1 may have three or more bends without losing the effects of the present invention.

[0074] The above-mentioned modification examples are applicable not only to the first embodiment but also to the second embodiment.

[0075] The present invention has been described above based on the embodiments and variations. However, the embodiments described above are examples to facilitate understanding of the present invention and are not intended to limit the present invention. Any modifications, improvements, and equivalent substitutions made within the spirit of the present invention and the scope of the claims shall be included within the scope of protection of the present invention. In addition, if a technical feature is not described as essential in this specification, it may be appropriately deleted.

[0076] Explanation of symbols

[0077] 1…catheter

[0078] 10…Hollow shaft

[0079] 11…First hollow shaft

[0080] 12…Second hollow shaft

[0081] 13…Third hollow shaft

[0082] 14…Connection between the first hollow shaft and the second hollow shaft

[0083] 15…Connection between the second hollow shaft and the third hollow shaft

[0084] 21…First section

[0085] 22…Second section

[0086] 23…the third section

[0087] 31…First bend

[0088] 32…Second bend

[0089] p1…vertex of the first bend

[0090] p2…vertex of the second bend

[0091] 40…imaginary plane

[0092] 41…imaginary line

[0093] 51…First Area

[0094] 52…Second Area

[0095] 60…front end

[0096] 70…Handle

[0097] 71…Protector

[0098] 72…Main part

[0099] 73…Connector

[0100] 100…blood vessels

[0101] 101…branched blood vessels

[0102] 102…blood vessel wall

[0103] L1…First distance (distance from the vertex of the first bend to the imaginary plane)

[0104] L2…Second distance (distance from the vertex of the second bend to the imaginary plane)

[0105] L3…The third distance (the distance from the front end of the hollow shaft to the imaginary plane)

[0106] C1…Center of the curvature radius Rc1 of the maximum curved portion Rmax1

[0107] C2... Center of the curvature radius Rc2 of the maximum curved portion Rmax2

Claims

1. A catheter comprising a hollow shaft, wherein: The front end portion of the hollow shaft has: a first section extending linearly; a second section connected to the front end side of the first section and forming a first curved portion; and a third section connected to the front end side of the second section and forming a second curved portion, The stiffness of the second interval is greater than the stiffness of the third interval, When an imaginary plane along the axis of the first section is set, and a spatial region on one side of the imaginary plane is set as a first region, and a spatial region on the other side of the imaginary plane is set as a second region, The first curved portion and the front end of the catheter are located in the first area, The second curved portion is located in the second area, The distance from the front end of the catheter to the imaginary plane is greater than the distance from the first curved portion to the imaginary plane. The distance from the second bend to the imaginary plane is greater than the distance from the first bend to the imaginary plane, The maximum curvature of the second curved portion is greater than the maximum curvature of the first curved portion.

2. The catheter according to claim 1, wherein The rigidity of the first section of the hollow shaft is greater than the rigidity of the second section.

3. The catheter according to claim 1 or 2, wherein: When the catheter is viewed from the front, the distal end of the first section of the hollow shaft, the apex of the first curved portion, and the apex of the second curved portion are arranged on a straight line.

Images