Medical catheter

Abstract

The utility model provides a medical catheter. The medical catheter comprises an inner layer, a middle layer and an outer layer which are sequentially sleeved from inside to outside. The middle layer comprises at least two fixing rings and a pull wire, and the fixing rings are arranged in the axial direction of the medical catheter at intervals; the stay wire is connected with the fixing ring at the farthest end; a bent section of the medical catheter is formed between the fixing ring at the farthest end and the other adjacent fixing ring, and the pull wire can drive the bent section to be bent. The far end of the medical catheter can be bent into shapes with different curvatures in real time, so that the requirements of blood vessels with different curvatures can be met, the catheter is smoothly bent, the use range of the catheter is expanded, and the catheter can flexibly cope with various bifurcated blood vessels in clinic.

Description

Technical Field

[0001] The utility model relates to the technical field of medical devices, and particularly relates to a medical catheter. Background Art

[0002] Cerebral hemorrhage refers to a disease of cerebral hemorrhage in non-traumatic cerebral parenchyma. The main causes of its occurrence are mainly related to the lesions of cerebral blood vessels, that is, related to hyperlipidemia, diabetes, hypertension or vascular aging. The traditional treatment method for cerebral hemorrhage is drug treatment, but the drug hemostasis is slow, and after intracranial coagulation occurs, craniotomy often leaves sequelae.

[0003] Interventional treatment surgery (such as arterial microcatheter dilation surgery and stent implantation surgery) is a diagnostic and treatment operation carried out by using a series of interventional instruments and modern digital diagnosis and treatment equipment. Compared with surgical operations, interventional treatment surgery only requires local anesthesia, and generally only a small incision of 1 mm to 2 mm needs to be made. This makes this method have the advantages of less bleeding, less trauma, fewer complications, faster postoperative recovery, safety and reliability, etc., thus greatly reducing the pain suffered by patients.

[0004] The catheter used in interventional treatment technology has a hollow cavity running through the entire tube body, so that drugs, guide wires or embolization substances (such as stents or coils) can be transported along the catheter to the affected area. During the operation, doctors usually operate the guide wire to reach the target site first, and the catheter follows the guide wire into the blood vessel branches. If a catheter with a straight tip is used, the catheter can only change its traveling direction by ramming the blood vessel wall, and it is difficult to enter the branch blood vessels with a large angle. In this way, not only more injuries are brought to the patient, but also the surgical treatment effect is affected.

[0005] The existing adjustable-bend catheter generally has a drawstring loop connected to a drawstring at the distal end of the catheter. When the drawstring is pulled, the entire tube body of the catheter will bend along with the drawstring, resulting in poor controllability when the catheter bends, so that the distal end of the catheter cannot enter the twisted and narrow blood vessels well. Summary of the Utility Model

[0006] The purpose of the utility model is to provide a medical catheter, the distal end of which can be bent into different curvature shapes in real time, so as to adapt to the blood vessel requirements of different curvatures, and then enable the catheter to smoothly turn, so as to expand the use range of the catheter and enable the catheter to flexibly cope with various bifurcated blood vessels in clinical practice.

[0007] To achieve the above-mentioned purpose, the utility model provides a medical catheter, comprising an inner layer, an intermediate layer and an outer layer which are sequentially sleeved from the inside to the outside; the intermediate layer comprises a fixing ring and a pull wire, the number of the fixing rings is at least two, and all the fixing rings are spaced apart in the axial direction of the medical catheter; the pull wire is connected to the fixing ring at the farthest end; a curved section of the medical catheter is formed between the fixing ring at the farthest end and another adjacent fixing ring, and the pull wire can drive the curved section to bend.

[0008] Optionally, all the fixing rings include a first fixing ring and a second fixing ring, the first fixing ring constitutes the most distal fixing ring, the second fixing ring is arranged at the proximal end of the first fixing ring, the bending section is formed between the first fixing ring and the second fixing ring, and the anti-bending section of the medical catheter is formed between the second fixing ring and the proximal end of the medical catheter, and the hardness of at least part of the anti-bending section is greater than the hardness of the bending section.

[0009] Optionally, the middle layer also includes a support layer and a braided layer; the support layer includes a first spiral segment and a second spiral segment; the first fixing ring, the first spiral segment, the second fixing ring and the second spiral segment are arranged in sequence from the distal end to the proximal end in the axial direction of the medical catheter to form the support layer; the braided layer is sleeved and abuts against the outer wall of the support layer.

[0010] Optionally, the first spiral segment is a spring tube, which is respectively abutted against the proximal end of the first fixing ring and the distal end of the second fixing ring; at least part of the second spiral segment is a sea wave tube, which is abutted against the proximal end of the second fixing ring, and the hardness of the sea wave tube is greater than that of the first spring tube.

[0011] Optionally, the medical catheter also includes a pull wire tube, which extends in the axial direction of the medical catheter and is respectively connected to the first fixing ring and the second fixing ring; the pull wire can be movably passed through the pull wire tube, and the hardness of the pull wire tube in the anti-bending section is greater than the hardness of the pull wire tube in the bending section.

[0012] Optionally, the pull wire includes a first pull wire and a second pull wire; the first pull wire is connected to the first fixing ring, and the connection position of the first pull wire and the first fixing ring is defined as a first connection position; the second pull wire is connected to the second fixing ring, and the connection position of the second pull wire and the second fixing ring is defined as a second connection position; the angle between the first connection position and the second connection position on the projection plane perpendicular to the axis of the medical catheter is 90°.

[0013] Optionally, after bending, the bent section has a bending position, and the length of the bending position and the distal end of the medical catheter in the axial direction of the medical catheter accounts for 1 / 2 to 2 / 3 of the total length of the bent section.

[0014] Optionally, the first helical section is a spring tube, and the spring tube includes a first section, a second section, and a third section connected in sequence from the distal end to the proximal end, and the bending position is arranged in the second section.

[0015] Optionally, the pitch of the second section is greater than the pitch of the first section and the third section, and / or the hardness of the second section is less than the hardness of the first section and the third section.

[0016] Optionally, the braiding density of the braided layer in the bending-resistant section is less than the braiding density of the braided layer in the bent section.

[0017] In the medical catheter provided by the present utility model, the distal end of the medical catheter has an adjustable-bend bent section, and the catheter can be bent into different curvature shapes in real time in the bent section, so as to adapt to the vascular requirements of different curvatures and ensure that the catheter can smoothly pass through the bend. The medical catheter can flexibly cope with various bifurcated blood vessels in clinical practice, so as to expand the use range of the catheter, simplify the surgical process, and shorten the surgical time, thereby solving the problems of difficult catheter bending and cumbersome steps. Description of the Drawings

[0018] Figure 1 It is a partial cross-sectional structural schematic diagram of a medical catheter in a preferred embodiment of the present utility model;

[0019] Figure 2 It is a partial three-dimensional structural schematic diagram of the inner layer, fixing ring and pull wire of a medical catheter in a preferred embodiment of the present utility model, wherein the catheter is in an unbent state;

[0020] Figure 3 It is a front view structural schematic diagram of the inner layer, fixing ring and pull wire of a medical catheter in a preferred embodiment of the present utility model, wherein the catheter is in an unbent state;

[0021] Figure 4 It is a front view structural schematic diagram of the inner layer, fixing ring and pull wire of a medical catheter in a preferred embodiment of the present utility model, wherein the catheter is in a bent state;

[0022] Figure 5 It is a three-dimensional structural schematic diagram of the inner layer, fixing ring and pull wire of a medical catheter in a preferred embodiment of the present utility model, wherein the catheter is in a bent state;

[0023] Figure 6 It is a simplified top view structural schematic diagram of a medical catheter in a preferred embodiment of the present utility model, wherein the catheter is in a bent state;

[0024] Figure 7 This is a schematic structural diagram of the inner layer and the support layer of a medical catheter in a preferred embodiment of the present utility model. Among them, the catheter has an orientation adjustment section;

[0025] Figure 8 This is a partial exploded structural diagram of the inner layer, the support layer and the outer layer of a medical catheter in a preferred embodiment of the present utility model;

[0026] Figure 9 This is a schematic structural diagram of the inner layer and the support layer of a medical catheter in a preferred embodiment of the present utility model;

[0027] Figure 10 This is a schematic structural diagram of the inner layer, the support layer and the braided layer of a medical catheter in a preferred embodiment of the present utility model. Among them, the catheter has two orientation adjustment sections;

[0028] Figure 11 This is a partial structural diagram of a guiding sheath tube in the first preferred embodiment of the present utility model;

[0029] Figure 12 This is a schematic diagram of the usage scenario of a guiding sheath tube in the first preferred embodiment of the present utility model;

[0030] Figure 13 This is a schematic structural diagram of a micro catheter in the second preferred embodiment of the present utility model.

[0031] [Explanation of the reference numerals is as follows]:

[0032] Catheter 1; inner layer 11; intermediate layer 12; fixing ring 121; first fixing ring 1211; second fixing ring 1212; fixing part 1213; round hole 1214; pull wire 122; first pull wire 1221; second pull wire 1222; support layer 123; first spiral section 1231; second spiral section 1232; first section 1233; second section 1234; third section 1235; braided layer 124; outer layer 13; hydrophilic coating 14; bending section 15; bending resistance section 16; pull wire tube 17; first part 171; second part 172;

[0033] First diffusion stress tube 21; second diffusion stress tube 22; first catheter seat 31; second catheter seat 32; guide wire 3; intermediate catheter 4. Detailed implementation manners

[0034] The following further elaborates on the present utility model in detail in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present utility model will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present utility model.

[0035] The terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0036] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or communicable with each other; it can be directly connected, or connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In the description of the present invention, the meaning of "a plurality of" is at least two, such as two or three or more.

[0037] As used in this specification, "distal end" generally refers to the end of the catheter away from the operator; the term "proximal end" is opposite to the "distal end" and generally refers to the end of the catheter close to the operator; the term "axial direction" refers to the direction along the axis of the catheter; the term "circumferential direction" refers to the direction of surrounding the axis of the catheter; the term "radial direction" refers to the direction perpendicular to the axis of the catheter.

[0038] The present invention will be described in detail below with reference to the drawings and preferred embodiments. Without conflict, the following embodiments and the features in the embodiments can be mutually supplemented or combined with each other.

[0039] As Figures 1 to 6 shown, a preferred embodiment of the present invention provides a medical catheter (hereinafter referred to as catheter 1), which is a single-lumen tube with a multi-layer structure, and the cross-sectional shape is usually circular.

[0040] Continue to refer to Figure 1 and Figure 2, the catheter 1 includes an inner layer 11, an intermediate layer 12, and an outer layer 13 that are sleeved in sequence from the inside to the outside along its radial direction. A hydrophilic coating 14 may also be attached to the outer surface of the outer layer 13. The intermediate layer 12 includes fixing rings 121 and a pulling wire 122. The number of fixing rings 121 is at least two, and all the fixing rings 121 are arranged at intervals in the axial direction of the catheter 1. The pulling wire 122 is connected to the most distal fixing ring 121. A bending section 15 is formed between the most distal fixing ring 121 and another adjacent fixing ring 121 at the distal end of the catheter 1, and the pulling wire 122 can drive the bending section 15 to bend.

[0041] In a preferred embodiment, all the fixing rings 121 are arranged between the inner layer 11 and the outer layer 13. One end of the pulling wire 122 extends to the proximal end of the catheter 1, and the other end passes through at least one fixing ring 121 and is connected to the most distal fixing ring 121. The operator can pull the pulling wire 122 at the proximal end, and after the pulling wire 122 is pulled, it can drive the catheter 1 to bend within the bending section 15.

[0042] In the medical catheter provided by the present application, the distal end of the catheter 1 has an adjustable bending section 15. The catheter 1 can be bent into shapes with different curvatures in real time within the bending section 15, so as to adapt to the vascular requirements with different curvatures and ensure the smooth bending of the catheter 1. The catheter 1 can flexibly cope with various bifurcated blood vessels in clinical practice, so as to expand the application range of the catheter 1, simplify the surgical process, and shorten the surgical time, thereby solving the problems of difficult bending and cumbersome steps of the catheter 1.

[0043] More specifically, when the distal end of the catheter 1 is stressed, the distal end of the catheter 1 will bend in the direction of the stress. When the stress at each position of the catheter 1 is uniform, the catheter 1 will bend at the position with lower hardness. The present utility model adopts the cooperation of the pulling wire 122 and the fixing ring 121 to bend the distal end of the catheter 1. Specifically, at least one pulling wire 122 is designed in the present application to control the distal end of the catheter 1 to bend in at least one direction, and the bending direction of the distal end of the catheter 1 faces the side of the pulling wire 122, that is, the bending direction of the catheter 1 and the fixing position of the pulling wire 122 are on the same side. The bending amplitude of the catheter 1 is proportional to the displacement of the pulling wire 122. That is to say, the greater the displacement of the stretching of the pulling wire 122, the greater the bending angle of the catheter body 1.

[0044] In order to improve the bonding between the inner layer 11 and the outer layer 13 when the catheter 1 is adjusted in direction, an adhesive material may also be added between the inner layer 11 and the outer layer 13 to form an adhesive layer.

[0045] The present application does not limit the material of the inner layer 11. The inner layer 11 can be prepared from materials such as polytetrafluoroethylene (PTFE), high-density polyethylene (HDPE), or other low-friction coefficient block polyether amide elastomers (Pebax) mixed with additives for reducing the friction coefficient. The inner layer 11 can be processed and formed by an extrusion process.

[0046] The present application does not limit the material of the fixing ring 121 either. The fixing ring 121 can be made of metal materials or polymer materials. In a specific example, the fixing ring 121 is preferably made of a metal imaging material. For example, platinum-iridium alloy or tantalum ring can be selected to locate the position of the fixing ring 121 during the operation. In another example, the fixing ring 121 can also be made of metal materials (such as stainless steel). At this time, imaging points can be added to the fixing ring 121. The imaging points are made of metal imaging alloy materials such as platinum-tungsten, platinum-iridium alloy, gold, platinum, and tantalum, so as to help the operator locate the position of the catheter 1 in the blood vessel.

[0047] The present application does not limit the material of the pull wire 122. The pull wire 122 can be made of medical polymers or medical metal materials. The pull wire 122 is preferably made of metal materials. For example, stainless steel, tungsten alloy, cobalt-chromium alloy, or nickel-titanium alloy can be selected. In addition, the pull wire 122 can also be made of other suitable materials.

[0048] The present application does not limit the material of the outer layer 13 either. The outer layer 13 is preferably made of medical polymer materials. For example, one or several elastic polymer materials such as thermoplastic polyurethane (TPU), block polyether amide resin (Pebax), high-density polyethylene (HDPE), nylon (Nylon), polyolefin (PO), and their modified materials can be selected for preparation. The outer layer 13 can select materials with different hardness levels for transition splicing as needed to adjust the hardness of different positions of the catheter 1 from the distal end to the proximal end.

[0049] The present application does not limit the material of the hydrophilic coating 14. The hydrophilic coating 14 on the surface of the outer layer 13 of the catheter 1 can be added with hydrophilic polymer additives, hydrophilic nano-polymer additives, polyethylene glycol stearate materials, or self-lubricating polymer materials. The hydrophilic polymer additives can adopt hydrophilic coatings such as hyaluronic acid, polyvinyl alcohol (PVA), polyethylene glycol (PEG), or polyvinylpyrrolidone (PVP). PVP is preferably added to reduce the friction between the catheter 1 and the inner wall of the blood vessel during the transportation of the catheter 1 in the human blood vessel.

[0050] Refer to Figures 3 to 6 As shown, in an alternative embodiment, all the fixing rings 121 include a first fixing ring 1211 and a second fixing ring 1212. The first fixing ring 1211 constitutes the fixing ring 121 at the most distal end, and the second fixing ring 1212 is arranged proximal to the first fixing ring 1211.

[0051] In this embodiment, the number of the fixing rings 121 is two. In other alternative embodiments, the number of the fixing rings 121 can also be set to one, three, or more.

[0052] In one example, the first fixing ring 1211 is sleeved on the distal end of the catheter 1, specifically on the distal end of the inner layer 11 of the catheter 1. The second fixing ring 1212 is arranged at the middle position of the catheter 1, and the middle position refers to the position of the catheter 1 other than the proximal end and the distal end. The pull wire 122 is connected to the first fixing ring 1211 and is used to drive the distal end of the catheter 1 to bend.

[0053] Furthermore, a bending section 15 is formed between the first fixing ring 1211 and the second fixing ring 1212, and an anti-bending section 16 of the catheter 1 is formed between the second fixing ring 1212 and the proximal end of the catheter 1. The hardness of at least a part of the anti-bending section 16 is greater than that of the bending section 15, that is, the flexibility of the anti-bending section 16 is less than that of the bending section 15. In this way, the straightness of the anti-bending section 16 can be improved, so that when the bending section 15 at the distal end of the catheter 1 bends, the anti-bending section 16 of the catheter 1 does not bend or only bends slightly, thereby avoiding the overall bending of the catheter 1, improving the controllability of the catheter 1 when bending, and ensuring that the catheter 1 can reach the lesion site during the operation.

[0054] Preferably, the hardness of the material of the outer layer 13 of the catheter 1 can gradually increase from the distal end to the proximal end along its own axis, so as to achieve that the hardness of the anti-bending section 16 in the outer layer 13 is greater than that of the bending section 15 in the outer layer 13, so that the proximal end of the catheter 1 has better torsion controllability and the distal end has better flexibility.

[0055] More preferably, the anti-bending section 16 adopts a multi-segment design along the axis of the catheter 1. Specifically, the hardness of each segment can be the same or different. In one solution, the hardness of multiple segments can be designed to gradually increase from the distal end to the proximal end. In this way, the hardness gradient of the anti-bending section 16 of the catheter 1 can be ensured to be small, the transition is good, and it is easy to realize the transmission of the acting force during the operation of the anti-bending section 16.

[0056] For the bending section 15, a multi-region design along the circumferential direction of the catheter 1 can be adopted. Specifically, the hardness of each region can be the same or different. In one example, the hardness of the inner side of the bending section 15 (i.e., the area on the side where the bending section 15 bends) during orientation can be designed to be less than the hardness of the outer side of the bending section 15 (i.e., the area on the opposite side where the bending section 15 bends) during orientation, so as to facilitate the realization of the bending and orientation functions.

[0057] This application does not limit the material and structure of the intermediate layer 12. The material of the intermediate layer 12 can include but is not limited to stainless steel or nitinol. The structure of the intermediate layer 12 can be made of a braided mesh or a spring coil. To improve the overall flexibility of the catheter 1, the stiffness of the intermediate layer 12 of the catheter 1 can be improved through multiple heat treatment processes.

[0058] Refer to Figure 7As shown, in an optional solution, a fixing portion 1213 for fixing the pull wire 122 is provided on the fixing ring 121, and the fixing portion 1213 can be set as a groove or a hole. In actual preparation, the pull wire 122 can be connected to the fixing portion 1213 by laser welding, soldering, bonding or winding. In addition, a circular hole 1214 is preferably also provided on the fixing ring 121, so that the circular hole 1214 can be used as a penetration hole for combining the materials of the inner layer 11 and the outer layer 13.

[0059] Reference Figures 7 to 10 As shown, in an optional embodiment, the intermediate layer 12 further includes a support layer 123 and a braided layer 124, and the support layer 123 includes a first spiral segment 1231 and a second spiral segment 1232. The first fixing ring 1211, the first spiral segment 1231, the second fixing ring 1212 and the second spiral segment 1232 are sequentially arranged from the distal end to the proximal end in the axial direction of the catheter 1 to form the support layer 123, and the braided layer 124 is sleeved and abutted against the outer wall of the support layer 123. The design of the support layer 123 can enable the catheter 1 to maintain the roundness of the cross section when bending, and avoid the catheter 1 from collapsing or bending. The design of the braided layer 124 can ensure that the catheter 1 will not be stretched, deformed or broken during the bending process.

[0060] Reference Figure 9 As shown, in a preferred embodiment, the first spiral section 1231 is a spring tube, which is respectively in contact with the proximal end of the first fixing ring 1211 and the distal end of the second fixing ring 1212. At least part of the second spiral section 1232 is a hypotube, which is in contact with the proximal end of the second fixing ring 1212. Since the hardness of the hypotube is generally greater than that of the spring tube, such a configuration can achieve that the hardness of the anti-bending section 16 is greater than the hardness of the bending section 15.

[0061] In other solutions, the first helical segment 1231 and the second helical segment 1232 may also be designed as a spring tube or a hypotube.

[0062] Furthermore, the spring tube can be wound with metal wire, for example, medical stainless steel wire. The metal wire can be in the form of round wire, flat wire or other shapes, and the pitch of the spring tube can be adjusted according to the application scenario of the product.

[0063] Preferably, in order to achieve a multi-stage hardness design of the catheter 1, the pitch of the distal end of the spring tube can be made greater than the pitch of the proximal end of the spring tube. For example, the distal end pitch of the spring tube can be set at approximately 2.5 to 4 times the spring wire diameter or spring wire width, and the proximal end pitch of the spring tube can be set at approximately 1.8 to 2.5 times the spring wire diameter or spring wire width, so that the distal end of the catheter 1 has better flexibility and the proximal end has better support.

[0064] Preferably, the braided layer 124 can be braided with braided wires. For example, it can be braided with medical stainless steel or medical nitinol wires. The form of the braided wires can be round wires, flat wires or a mixture of round wires and flat wires for braiding.

[0065] Since it cannot be guaranteed that the bending direction of the catheter 1 after bending is towards the port of the target blood vessel, during the operation, it is often necessary to twist and control the catheter 1 at the proximal end, thereby changing the extension direction of the distal end of the catheter 1. Specifically, the operator can rotate the catheter 1 at the proximal end of the catheter 1. If the catheter 1 has good twist control, the turning force received at the proximal end of the catheter 1 can be transmitted to the distal end, thereby enabling the distal end of the catheter 1 to rotate until the distal end of the catheter 1 is aligned with the port of the target blood vessel. It should be understood that the target blood vessel here refers to the blood vessel with a diseased site, that is, the diseased blood vessel.

[0066] Since the twist control of the catheter 1 is related to the braiding density of the braided wires of the braided layer 124 and the strength of the braided wires. Generally speaking, the higher the strength of the braided wires of the braided layer 124, the better the twist control of the catheter 1. At this time, the force received at the proximal end of the catheter 1 can be smoothly transmitted to the distal end; the lower the strength of the braided wires of the braided layer 124, the higher the softness of the catheter 1 and the lower the hardness. And the higher the braiding density of the braided wires, the higher the softness of the catheter 1 and the lower the strength of the braided layer 124 to improve the flexibility of the catheter 1, that is, to make the catheter 1 easier to bend and deform; the lower the braiding density of the braided wires, the better the twist control of the catheter 1. Therefore, the twist control of different regions of the catheter 1 can be adjusted by adjusting the strength and braiding density of the braided wires in different regions of the catheter 1, so that the catheter 1 can flexibly adjust the bending direction of the bending section 15 during the operation, so as to facilitate the catheter 1 to quickly and accurately guide other instruments into the target pipeline.

[0067] In order to achieve the multi-segment hardness design of the catheter 1, the braiding density of the braided layer 124 in the anti-bending section 16 is preferably less than the braiding density of the braided layer 124 in the bending section 15, so as to further make the catheter 1 take into account the flexibility of the distal end and the support of the proximal end, and can improve the twist control of the catheter 1. In one example, the strength of the braided wire 124 can be changed by a heat treatment process.

[0068] More specifically, for the distal end of the catheter 1, since the hardness of the outer layer 13 is relatively low, the middle layer 12 has the greatest influence on the twist control of the catheter 1. Among them, the braided layer 124 has a greater influence on the twist control than the support layer 123. In actual design, the strength of the catheter body 1 can be adjusted by adjusting the outer diameters of the support layer 13 and the braided layer 124 and the wire diameters of the braided wires as needed. In addition, the braiding density of the middle layer 12 can also be adjusted according to the braiding form, braiding grid density and the number of braided wires of the braided layer 124, thereby adjusting the twist control of the catheter body 1.

[0069] To ensure that the distal end of the catheter 1 has a lower hardness and better torsional controllability, high-strength braided wires can be selected for braiding the distal end of the catheter 1, and a relatively high braiding density can be adopted. Preferably, the braiding density of the braided wires can be set to 100 PPI to 120 PPI (PPI refers to the number of grids per inch), and the strength of the braided wires should be greater than 2200 Mpa.

[0070] For the middle part of the catheter 1 (i.e., the part of the catheter 1 excluding the distal end and the proximal end), since the hardness of the outer layer 13 is moderate, the braiding density and / or the strength of the braided wires of the braided layer 124 can be appropriately reduced. For example, the strength of the braided wires can be reduced by means of heat treatment to ensure that the middle part of the catheter 1 has a moderate hardness and better torsional controllability. Preferably, the braiding density of the braided wires can be set to 75 PPI to 95 PPI, and the strength of the braided wires can be appropriately reduced.

[0071] For the proximal part of the catheter 1, since the hardness of the outer layer 13 is relatively large, the influence of the middle layer 12 on the hardness of the catheter 1 is very small at this time. Therefore, the braiding density of the braided layer 124 can be reduced, and the strength of the braided wires can be adjusted as needed to improve the torsional controllability of the catheter 1. Preferably, the braiding density of the braided wires can be set to 60 PPI to 80 PPI, and the strength of the braided wires can be set as needed.

[0072] In addition, for the braided layer 124 with the same braiding density, braiding with multiple strands of wire can also improve the torsional controllability of the catheter 1. In this embodiment, 16 strands of metal wires can be used for braiding to enable the catheter 1 to obtain the required performance.

[0073] Refer to Figure 9 and Figure 10 As shown, in a preferred embodiment, the number of the pull wires 122 is at least two, and each pull wire 122 is connected to a corresponding fixing ring 121.

[0074] In a better solution, the number of the fixing rings 121 is the same as the number of the pull wires 122, and both are at least two. At this time, each pull wire 122 is connected to a corresponding fixing ring 122. The operator can pull different pull wires 122 to achieve multi-position and multi-angle bending of the catheter 1 through different fixing rings 122, and thus can flexibly control the moving position of the distal end of the catheter 1.

[0075] In a specific example, the first pull wire 1221 can be connected to the first fixing ring 1211, and the second fixing ring 1211 is not connected to a pull wire. At this time, when the first pull wire 1221 is pulled, the catheter 1 can also be bent within the bending section 15.

[0076] In another alternative, the number of fixing rings 121 can also be greater than the number of pull wires 122. In this case, except for the fixing ring 121 at the farthest end (i.e., the first fixing ring 1211), one or more of the remaining fixing rings 121 may not be connected to the pull wire 122, but only arranged between the inner layer 11 and the outer layer 13.

[0077] As Figure 9 and Figure 10 shown, as a preferred embodiment, the number of both the fixing rings 121 and the pull wires 122 is two. The pull wire 122 includes a first pull wire 1221 and a second pull wire 1222. The first pull wire 1221 is connected to the first fixing ring 1212, and the connection position between the first pull wire 1221 and the first fixing ring 1212 is defined as the first connection position. The second pull wire 1222 is connected to the second fixing ring 1212, and the connection position between the second pull wire 1222 and the second fixing ring 1212 is defined as the second connection position. The angle between the projections of the first connection position and the second connection position on the plane perpendicular to the axis of the catheter 1 is 90°. That is to say, on the projection plane of the catheter 1 perpendicular to its own axial direction, the line connecting the first connection position and the geometric center of the catheter 1 is perpendicular to the line connecting the second connection position and the geometric center of the catheter 1.

[0078] With such a configuration, the first pull wire 1221 can drive the distal end of the catheter 1 to bend in the first direction through the first fixing ring 1211, and the second pull wire 1222 can drive the distal end of the catheter 1 to bend in the second direction through the second fixing ring 1212. The first direction and the second direction are perpendicular. Arranging multiple pull wires 122 can enable the catheter 1 to bend in different directions at different positions, so as to facilitate the catheter 1 to pass through more complex and tortuous blood vessels and improve the passing rate of the catheter 1 in the blood vessels.

[0079] In the catheter 1, the inner layer 11, the first helical section 1231, the braided layer 124, the outer layer 13 and the hydrophilic coating 14 form the bending section 15 of the catheter 1. Pulling the first pull wire 1221 connected to the first fixing ring 1211 can cause the bending section 15 to bend. The inner layer 11, the second helical section 1232, the braided layer 124, the outer layer 13 and the hydrophilic coating 14 form the bending-resistant section 16 of the catheter 1. Pulling the second pull wire 1222 connected to the second fixing ring 1212 can cause the bending-resistant section 16 to bend.

[0080] More specifically, the intermediate layer 12 of the catheter 1 forms a plurality of steering sections connected in sequence from the distal end to the proximal end along its own axial direction. Each steering section can provide the function of bending the catheter 1 at any angle in one direction or multiple directions. When the number of steering sections is multiple, multi-directional bending control of the catheter 1 can be achieved.

[0081] Referring to Figure 10As shown, in this embodiment, the number of the direction-adjusting sections is two, the first fixing ring 1211, the first pull wire 1221, the spring tube and the braided layer 124 constitute the first direction-adjusting section a, and the second fixing ring 1211, the second pull wire 1222, the hypotube and the braided layer 124 constitute the second direction-adjusting section b. When the first pull wire 1221 is pulled, the first direction-adjusting section a can be driven to bend, so that the distal end of the catheter 1 bends toward the first direction (for example, the distal end of the catheter 1 bends toward the distal end of the catheter 1). Figure 10 When the second pull line 1222 is pulled, the second adjustment section b can be driven to bend so that the distal end of the catheter 1 bends toward the second direction (for example, the distal end of the catheter 1 bends toward Figure 10 ), where the first direction and the second direction are perpendicular to each other.

[0082] Return to reference Figures 3 to 5 As shown, in some embodiments, the catheter 1 further includes a wire drawing tube 17, which extends in the axial direction of the catheter 1 and is connected to the first fixing ring 1211 and the second fixing ring 1212 respectively, for example, by welding. The wire drawing tube 17 is arranged between the inner layer 11 and the support layer 123, and is close to the outer wall of the inner layer 11 and the inner wall of the support layer 123. The wire 122 can be movably passed through the wire drawing tube 17, and the hardness of the wire drawing tube 17 in the anti-bending section 16 is greater than the hardness of the wire drawing tube 17 in the bending section 15, so as to help ensure the straightness of the anti-bending section 16, and avoid the anti-bending section 16 from being greatly bent synchronously when the bending section 15 is bent, thereby affecting the controllability of the catheter 1.

[0083] Reference Figure 9 and Figure 10 As shown, in a preferred embodiment, the first pull wire 1221 and the second pull wire 1222 are both inserted into a corresponding pull wire tube 17. At the proximal position of the outer layer 13, the first pull wire 1222 and the corresponding pull wire tube 17 simultaneously pass through the braided layer 124 and the outer wall of the outer layer 13, and extend to the outside of the outer layer 13. The second pull wire 1222 and the corresponding pull wire tube 17 simultaneously pass out from the proximal end of the outer layer 13. When the proximal end of the first pull wire 1221 or the second pull wire 1222 is pulled, the first pull wire 1221 or the second pull wire 1222 can move axially in the corresponding pull wire tube 17, thereby driving the catheter 1 to bend toward one side of the pull wire 122 to assist the distal end of the catheter 1 to enter the target blood vessel.

[0084] Better, continue to refer to Figure 3 The wire pulling tube 17 includes a first part 171 and a second part 172 connected in sequence from the distal end to the proximal end, wherein at least part of the first part 171 is arranged in the bending section 15 of the catheter 1, and at least part of the second part 172 is arranged in the anti-bending section 16 of the catheter 1.

[0085] In actual use, while pulling the pull wire 122, the second part 172 of the pull wire tube 17 can be pushed distally to further ensure the straightness of the anti-bending section 16, so that when the bending section 15 bends, it is not easy to drive the anti-bending section 16 to bend.

[0086] This application does not limit the material of the pull wire tube 17 either. The pull wire tube 17 can be prepared from a metal material or a polymer material. In a specific example, the pull wire tube 17 is arranged axially along the catheter 1 between the inner layer 11 and the support layer 123 of the entire catheter 1. Among them, the first part 171 of the pull wire tube 17 is preferably a PTFE tube (polytetrafluoroethylene tube) to facilitate the bending of the bending section 15. The second part 172 of the pull wire tube 17 can be a PI tube (polyimide tube), a stainless steel tube, a spring or other pipe fittings with higher hardness to ensure the straightness of the anti-bending section 16.

[0087] In this embodiment, the first part 171 of the pull wire tube 17 can be set as a PTFE tube, and the second part 172 of the pull wire tube 17 can be set as a spring cavity. At this time, the strength of the spring cavity is greater than that of the PTFE tube.

[0088] Furthermore, in order to ensure that the anti-bending section 16 has better straightness, the spring cavity needs to have a higher strength. In actual design, on the one hand, the strength of the spring cavity can be improved by increasing the inner diameter of the spring cavity. For example, a spring cavity with an outer diameter greater than 0.1 mm can be selected. On the other hand, the strength of the spring cavity can be judged by the strength of the wire material used to wind the spring cavity. That is, a spring cavity with a higher strength of the winding wire material can be selected to improve the strength of the spring cavity. The strength of the metal wire used to wind the spring cavity is preferably greater than 2400 Mpa.

[0089] <Example 1>

[0090] With the continuous accumulation of experience in transradial artery (TRA) cerebral angiography, its application in neurointerventional therapy is also increasing. Most posterior circulation lesions use the method of establishing a pathway through the ipsilateral TRA, while anterior circulation lesions often require the assistance of a Simmons angiography catheter to establish a pathway. The exchange technique is often used in the establishment of the TRA pathway, but the operation difficulty is high and there is a certain risk. The coaxial technique is also helpful for the establishment of the TRA pathway. The technique of combining specific instruments to establish a pathway is called the R-DAS technique (transradial telescoping catheter technique with a distal accesscathecatheter and Simmons catheter), that is, the coaxial technique of the distal access catheter and the Simmons catheter via the transradial artery approach. Currently, the design principle and operation method of the transradial artery catheter system (using the RIST catheter) already on the market abroad are the same as those of the R-DAS technique. This catheter has been applied clinically and achieved good results.

[0091] Whether it is the exchange technique or the R-DAS technique, their core is to achieve superselection with the combined action of the Simmons catheter and the guide wire, so as to send the long guiding sheath into the target blood vessel. However, both of them have some drawbacks or deficiencies. The exchange technique requires the use of a Simmons catheter and a relatively stiff long loach super-slippery guide wire. The super-slippery guide wire is introduced into the aorta under the lower wall of the aortic arch, the catheter is introduced along the guide wire into the descending aorta, the guide wire is withdrawn, the catheter is withdrawn and rotated clockwise, and a loop can be formed naturally in the ascending aorta (that is, the inherent shape of the catheter tip is restored in the blood vessel), and then the catheter enters the target blood vessel along the guide wire. This process has a high operation difficulty and the following risks: First, the friction between the guide wire or catheter and the aortic wall is large, and spasm is more likely to occur; Second, for patients with tortuous type II or type III aortic arches, it is very difficult to send the guide wire to the descending aorta, so the Simmons catheter loop cannot be completed.

[0092] The operation method of the coaxial technique is as follows: A coaxial system is formed by using a 125-cm Simmons type II angiographic catheter and a distal access catheter (or an intermediate catheter and a high-performance long sheath). After the Simmons catheter successfully superselects the target blood vessel, the distal access catheter is transported to the target position in a coaxial manner by using the support of the Simmons catheter and the guide wire superselected to the distal end; This technique has more advantages than the exchange technique, but there are also some deficiencies: First, during the process of achieving Simmons catheter superselection, the Simmons catheter and the intermediate catheter need to be twisted and controlled simultaneously, and this process requires certain operation experience and operation time; Second, an intermediate catheter with a soft tip is required, and the intermediate catheter can reach a high enough position to establish a stable access, so the requirement for the positioning of the intermediate catheter is high; Third, due to the limitation of the Simmons catheter specifications, the selection range of the intermediate catheter is also limited.

[0093] Refer to Figure 1 As shown, in this embodiment, the medical catheter is a guiding sheath, and the guiding sheath includes a catheter 1, a first diffusion stress tube 21, and a first catheter seat 31 that are sequentially connected from the distal end to the proximal end. The catheter 1 includes an inner layer 1, an intermediate layer 12, an outer layer 13 that are sequentially sleeved along its own radial direction, and a hydrophilic coating 14 attached to the surface of the outer layer 13.

[0094] The distal end of the guiding sheath provided in this embodiment can adjust the bending angle in real time, so as to adapt to the blood vessel requirements of different curvatures, ensure that the guiding sheath can smoothly bend during the radial artery approach, without the use of a Simmons catheter, simplify the surgical process, and shorten the surgical time.

[0095] More specifically, the existing aortic arches are divided into type I arch, type II arch, and type III arch. Among them, the shapes of type II arch and type III arch are relatively complex, and it is more difficult for the catheter 1 to pass through. When passing through the type I arch, a catheter 1 with only one steering section can be used, that is, the catheter 1 is designed as a unidirectional bending structure (as Figure 7 shown). At this time, when the pull wire 122 is pulled, the distal end of the catheter 1 can bend towards the side of the pull wire 122, so that the distal port of the catheter 1 is aligned with the target blood vessel. If the bending direction of the catheter 1 deviates, the proximal end of the catheter 1 can be rotated, and the torsional force at the proximal end of the catheter 1 can be transmitted to the distal end of the catheter 1 by using the torsional control of the catheter 1, so that the distal end of the catheter 1 rotates until the distal end of the catheter 1 can be aligned with the port of the target blood vessel after bending.

[0096] Please refer to Figure 11 , in a preferred solution, after the bending section 15 is bent, it has a bending position (not labeled). The length of the bending position and the distal end of the catheter 1 in the axial direction of the catheter 1 accounts for 1 / 2 to 2 / 3 of the total length of the bending section 15. The total length of the bending section 15 refers to the length of the bending section 15 in the axial direction of the catheter 1. By setting like this, the distance between the distal end of the catheter 1 and the target blood vessel can be reduced, which helps the instruments passing through the catheter 1 to enter the target blood vessel more accurately.

[0097] It should be understood that the ratio of the length of the bending position and the distal end of the catheter 1 in the axial direction of the catheter 1 to the total length of the bending section 15 can be determined according to the blood vessel shapes of different patients. Generally speaking, the distance between the bending position and the distal end of the catheter 1 accounts for 1 / 2 to 2 / 3 of the total length of the bending section 15.

[0098] Continuing to refer to Figure 11 , in a specific embodiment, the first helical section 1231 is a spring tube. The spring tube includes a first section 1233, a second section 1234, and a third section 1235 that are connected in sequence from the distal end to the proximal end. The bending position is arranged on the second section 1234.

[0099] Since the relative positional relationship among the brachiocephalic trunk, left common carotid artery, and left subclavian artery of the aortic arch of different patients is relatively complex and has a certain inclination angle. With such a structure, the length of the extension section between the bending position of the catheter 1 and the distal end of the catheter 1 can be increased. At this time, the length of the distal bent part of the catheter 1 after bending is longer, so that when the catheter 1 passes through the aortic arch and enters the target pipeline (such as the common carotid artery blood vessel), the distal end of the catheter 1 can be inserted into or close to the port of the target pipeline, thereby ensuring the smooth progress of the operation.

[0100] Specifically, the total length of the bending section 15 is L1, the length of the second section 1232 in the axial direction of the catheter 1 is L2, then the length L3 of the first section 1231 in the axial direction of the catheter 1 = 2 / 3L1 - 1 / 2L2, and the length L4 of the third section 1231 in the axial direction of the catheter 1 = 1 / 3L1 - 1 / 2L2.

[0101] In this embodiment, the length L1 of the bending section 15 in the axial direction of the catheter 1 is about 35 mm, and the length L2 of the second section 1232 in the axial direction of the catheter 1 is 3 mm to 5 mm.

[0102] In a specific solution, the first helical section 1231 is set as a corrugated tube. The pitches of the first section 1231 and the third section 1233 of the corrugated tube are the same or different, preferably the same. The pitch of the second section 1232 of the corrugated tube is greater than the pitches of the first section 1231 and the third section 1232 respectively. In this case, the bending section 15 can be bent at the second section 1232 after being stressed.

[0103] In another specific solution, the outer layer 13 of the bending part 15 of the catheter 1 adopts a multi-segment hardness design. When the first helical section 1231 is set as a corrugated tube, the hardness of the second section 1232 of the corrugated tube is less than the hardness of the first section 1231 and the third section 1232, so that the bending section 15 can be bent at the second section 1232 after being stressed.

[0104] In an embodiment, the hardness of the first section 1231 and the third section 1233 of the outer layer 13 is basically the same, and the hardness of the second section 1232 is less than the hardness of the first section 1231 and the third section 1233 respectively.

[0105] Refer to Figure 12 As shown, in a non-limiting embodiment, the catheter 1 can be used for radial artery interventional surgery. Specifically, when performing interventional surgery through the right radial artery, the puncture site can be punctured first, and the catheter 1 can be sent into the right radial artery along the guide wire 4 from the distal end. Under the guidance of the guide wire 4, the catheter 1 enters the aortic arch from the brachiocephalic trunk. Gently pull the first pull wire 1221 to make the distal end of the catheter 1 bend slightly. Determine the bending direction here under fluoroscopy, and then twist and control the catheter 1 so that the bending direction of the distal end of the catheter 1 faces the left common carotid artery ostium. Then continue to pull the first pull wire 1221 to align the distal end of the catheter 1 with the left common carotid artery ostium, and then send the guide wire 4 into the left common carotid artery. Subsequently, the intermediate catheter 5 is sent into the left common carotid artery along the guide wire 4.

[0106] In one case, during the process of aligning the distal end of the catheter 1 with the orifice of the left common carotid artery, if the distal orifice of the catheter 1 is in good alignment with the orifice of the left common carotid artery, but the distance between the distal orifice of the catheter 1 and the orifice of the common carotid artery is relatively far, the catheter 1 can be retracted backward at this time. Since the distal end of the catheter body 1 has been bent toward the left common carotid artery, retracting the catheter 1 can reduce the distance between the distal end of the catheter 1 and the orifice of the common carotid artery, facilitating the entry of the guide wire 4 and the intermediate catheter 5 into the common carotid artery.

[0107] In another case, if it is judged under angiography that the distal end of the catheter 1 is in good alignment with the orifice of the common carotid artery, but the guide wire 4 cannot be inserted into the common carotid artery, the aortic arch of the patient is generally a type II arch or a type III arch in this case. This situation is generally that the distal orifice of the catheter 1 is higher or lower than the orifice of the common carotid artery. At this time, the second draw wire 1222 needs to be pulled to move the distal end of the catheter 1 toward the position of the orifice of the common carotid artery. For example, the distal end of the catheter 1 can be offset downward by a certain angle through the second draw wire 1222 to accurately align the distal end of the catheter 1 with the orifice of the common carotid artery, so that the instruments (such as the guide wire 4 and the intermediate catheter 5) can quickly and accurately enter the orifice of the common carotid artery.

[0108] During the actual operation, if the bending section 15 of the catheter 1 swings when the first draw wire 1221 or the second draw wire 1222 is pulled, this situation is generally caused by the fact that the anti-bending section 16 of the catheter 1 cannot maintain good straightness. At this time, the operator can push the draw wire tube 17 toward the distal end, and the draw wire tube 17 can keep the anti-bending section 16 in good straightness, avoiding the swinging phenomenon during the bending process of the distal end of the catheter 1.

[0109] It should be understood that the catheter 1 can also be used for interventional surgery through the left radial artery, and its implementation method is similar to that through the right radial artery, so it will not be elaborated here.

[0110] In the medical catheter provided in this embodiment, the problem that it is difficult for the interventional instrument to enter the common carotid artery during the neurointerventional treatment of the internal carotid artery or the intracranial artery through the radial artery approach can be solved by the adjustable orientation of the distal end of the catheter 1 and the good torque control of the proximal end of the catheter 1, ensuring that the catheter 1 can fully play a good guiding role during the operation, enabling other instruments to be in place smoothly during the operation, and ensuring the smooth progress of the interventional surgery through the radial artery. Compared with the currently commonly used descending aortic loop technique, the operation time is greatly shortened, the damage to the human body during the operation is reduced, and the operation comfort of the patient is improved.

[0111] In addition, the catheter 1 can also reduce the operation difficulty, reduce the friction between the catheter 1 and the blood vessel wall of the aortic arch, improve the operation efficiency and the accuracy of the instrument in place, and improve the operation comfort of the patient.

[0112] <Example Two>

[0113] Cerebral nerve interventional therapy refers to creating a small hole at the femoral artery blood vessel site in the human body, and then inserting a microcatheter deep into the cerebral blood vessels of the patient to perform minimally invasive endovascular surgery for cerebrovascular diseases. Due to the complexity of blood vessels, the performance requirements for the microcatheter are very high. The microcatheter needs to have sufficient flexibility, torsional resistance, tracking ability, supportability, and fold resistance, etc., to ensure that the microcatheter can bend along the patient's blood vessels during the operation and can respond promptly and accurately to the doctor's operations such as pushing, pulling, and twisting.

[0114] In the prior art, in order to improve the operability of the catheter, during the operation, the main method is to perform steam reshaping on the pre-shaped microcatheter to improve the bending ability of the microcatheter, so that the microcatheter can smoothly pass through the tortuous and narrow blood vessels and selectively enter the bifurcated target lumen. However, the microcatheter prepared by the pre-shaping method may not be able to meet the requirements of blood vessels at special angles at one time after entering the blood vessels, which may require replacing the microcatheter or reshaping again during the operation. Multiple reshaping may result in poor shape retention ability at the tip of the microcatheter, making it impossible to perform selective intubation, that is, the catheter cannot selectively enter a certain blood vessel.

[0115] Refer to Figure 13 As shown, in this embodiment, the medical catheter is a microcatheter. The microcatheter includes a catheter 1, a second diffusion stress tube 22, and a second catheter seat 32 that are sequentially connected from the distal end to the proximal end. The catheter 1 includes an inner layer 1, an intermediate layer 12, an outer layer 13 that are sequentially sleeved along its own radial direction from the inside to the outside, and a hydrophilic coating 14 attached to the surface of the outer layer 13. The tip of the microcatheter has an adjustable bending section 15, which can bend the catheter 1 into different curvature shapes in real time, so as to adapt to the blood vessel requirements of different curvatures and ensure that the catheter 1 can smoothly pass through the bend.

[0116] Refer to Figure 13 As shown, in a non-limiting embodiment, the catheter 1 can be designed as a microcatheter. When performing an operation with the microcatheter, the operator first inserts the guide wire 4 into the arterial blood vessel and reaches the target blood vessel (i.e., the diseased blood vessel). After the catheter 1 reaches the target blood vessel, the guide wire 4 is passed out from the distal end of the catheter 1, and then the catheter 1 is pushed along the guide wire 4. When passing through the tortuous and complex blood vessels, the pull wire 122 can be pulled to adjust the bending of the distal end of the catheter 1, so that the catheter 1 can adapt to the bending path of the bifurcated blood vessel and can smoothly pass through the target blood vessel until it is pushed to the diseased part of the blood vessel, thus completing the operation.

[0117] In summary, in the medical catheter provided by the present utility model, the distal end of the catheter 1 has an adjustable bending section. The catheter 1 can be bent into shapes with different curvatures in real time at the bending section 15, so as to adapt to the vascular requirements with different curvatures and ensure that the catheter 1 can smoothly pass through the bend. The catheter 1 can flexibly cope with various bifurcated blood vessels in clinical practice, so as to expand the application range of the catheter 1, simplify the surgical process, and shorten the operation time, thereby solving the problems of difficult bending and cumbersome steps of the catheter 1.

[0118] The above description is only a description of the preferred embodiments of the present utility model, and does not limit the scope of the present utility model in any way. Any changes and modifications made by those of ordinary skill in the art of the present utility model according to the above disclosure shall fall within the protection scope of the present utility model.

Claims

1. A medical catheter, characterized in that, It comprises an inner layer, a middle layer and an outer layer which are sequentially sleeved from the inside to the outside; the middle layer comprises a fixing ring and a pull wire, the number of the fixing rings is at least two, and all the fixing rings are spaced apart in the axial direction of the medical catheter; the pull wire is connected to the fixing ring at the farthest end; a bending section of the medical catheter is formed between the fixing ring at the farthest end and another adjacent fixing ring, and the pull wire can drive the bending section to bend; all the fixing rings comprise a first fixing ring and a second fixing ring, the first fixing ring constitutes the fixing ring at the farthest end, the second fixing ring is arranged at the proximal end of the first fixing ring, the bending section is formed between the first fixing ring and the second fixing ring, the anti-bending section of the medical catheter is formed between the second fixing ring and the proximal end of the medical catheter, and the hardness of at least part of the anti-bending section is greater than the hardness of the bending section.

2. The medical catheter according to claim 1, wherein, The middle layer also includes a support layer and a braided layer; the support layer includes a first spiral segment and a second spiral segment; the first fixing ring, the first spiral segment, the second fixing ring and the second spiral segment are arranged in sequence from the distal end to the proximal end in the axial direction of the medical catheter to form the support layer; the braided layer is sleeved and abuts against the outer wall of the support layer.

3. The medical catheter according to claim 2, wherein, The first spiral section is a spring tube, which is respectively abutted against the proximal end of the first fixing ring and the distal end of the second fixing ring; at least part of the second spiral section is a sea wave tube, which is abutted against the proximal end of the second fixing ring, and the hardness of the sea wave tube is greater than that of the spring tube.

4. The medical catheter according to claim 1, characterized in that, It also includes a wire drawing tube, which extends in the axial direction of the medical catheter and is respectively connected to the first fixing ring and the second fixing ring; the pull wire can be movably passed through the wire drawing tube, and the hardness of the wire drawing tube in the anti-bending section is greater than the hardness of the wire drawing tube in the bending section.

5. The medical catheter according to any one of claims 1-4, characterized in that, The pull wire includes a first pull wire and a second pull wire; the first pull wire is connected to the first fixing ring, and the connection position of the first pull wire and the first fixing ring is defined as a first connection position; the second pull wire is connected to the second fixing ring, and the connection position of the second pull wire and the second fixing ring is defined as a second connection position; the angle between the first connection position and the second connection position on the projection plane perpendicular to the axis of the medical catheter is 90°.

6. The medical catheter according to claim 2, wherein, The bending section has a bending position after being bent, and the length between the bending position and the distal end of the medical tube in the axial direction of the medical tube accounts for 1 / 2 to 2 / 3 of the total length of the bending section.

7. The medical catheter according to claim 6, characterized in that, The first spiral section is a spring tube, which includes a first section, a second section and a third section which are sequentially connected from the distal end to the proximal end, and the bending position is arranged on the second section.

8. The medical catheter according to claim 7, characterized in that, The pitch of the second section is greater than the pitch of the first section and the third section, respectively, and / or the hardness of the second section is less than the hardness of the first section and the third section.

9. The medical catheter according to claim 2, wherein, The braiding density of the braided layer in the anti-bending section is smaller than the braiding density of the braided layer in the bending section.

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