A microcatheter

Abstract

The application provides a micro catheter, comprising a tube body, the tube body comprising an inner layer, an intermediate layer and an outer layer, the intermediate layer comprising a reinforcing area, a body area and a weakening area arranged in sequence along the circumferential direction of the tube body, the bending stiffness of the reinforcing area, the body area and the weakening area decreasing in sequence. Therefore, the bending stiffness of the tube body on the side of the reinforcing area is stronger, so that the micro catheter has better pushing performance and supportability on the side of the reinforcing area, and the kinking caused by the transitional bending of the micro catheter can be avoided. Meanwhile, the bending stiffness of the tube body on the side of the weakening area is smaller, the local flexibility is higher, and the bending performance is better. The body area maintains the basic stiffness and performance of the tube body and forms a smooth transition between the reinforcing area and the weakening area, so that the local stress concentration does not cause the bending failure of the catheter, thereby realizing the passability of the micro catheter in special tortuous blood vessels and the plasticity of the head end.

Description

Technical Field

[0001] This application relates to the field of medical devices, and more specifically, to a microcatheter. Background Technology

[0002] Medical catheters are tubular medical devices primarily used for medical diagnosis, treatment, and assisted procedures. They are typically made of soft, biocompatible polymer materials such as silicone, polyurethane, polyvinyl chloride, nylon, and nylon-block elastomer (Pebax). Some specialized catheters may also include auxiliary devices such as metal guidewires, metal layers, or balloons to meet the needs of different medical scenarios. Their components generally include a tubular body (single-layer or multi-layer composite structure) and connectors (catheter hubs, Luer conical connectors), such as microcatheters and balloon catheters. Medical catheters are widely used in various medical scenarios, including but not limited to the cardiovascular system (such as central venous catheters and balloon dilation catheters), the respiratory system (such as endotracheal intubation), the urinary system (such as urinary catheters), the digestive system (such as gastrointestinal drainage tubes), and neurosurgery (such as ventricular drainage tubes).

[0003] Microcatheters are ultra-thin (outer diameter typically <2.0 Fr), highly flexible interventional catheters used for precise delivery or interventional treatment in complex vascular pathways. When navigating certain bends in blood vessels, high flexibility and support are required at the catheter tip. For example, to accommodate the U-shaped bends in intracranial vessels, the tip must have a small bending radius ≤1 mm.

[0004] Microcatheters need to have a certain pushing performance as well as good bending performance. However, existing microcatheters need to balance pushing performance and bending performance, resulting in poor overall performance. Utility Model Content

[0005] The purpose of this application is to provide a microcatheter with good delivery performance and good bending performance.

[0006] This application provides a microcatheter, including a tube body, which includes an inner layer, an intermediate layer, and an outer layer. The intermediate layer includes a reinforcing region, a body region, and a weakening region arranged sequentially along the circumferential direction of the tube body, and the bending stiffness of the reinforcing region, the body region, and the weakening region decreases sequentially.

[0007] In the above technical solution, the intermediate layer has a reinforcing zone, a body zone, and a weakening zone arranged sequentially in the circumferential direction, and the bending stiffness of the reinforcing zone, body zone, and weakening zone decreases sequentially. Therefore, the bending stiffness of the tube body on the reinforcing zone side is stronger, which makes the microcatheter have better pushing performance and support on the reinforcing zone side, and can avoid the microcatheter from excessive bending and kinking. At the same time, the bending stiffness of the tube body on the weakening zone side is smaller, with higher local compliance and better bending performance. In addition, the tube body also includes a body zone with stiffness located between the reinforcing zone and the weakening zone. The body zone maintains the basic stiffness and performance of the tube body and forms a smooth transition between the reinforcing zone and the weakening zone, avoiding local stress concentration that could lead to microcatheter bending failure, thereby realizing the passage of the microcatheter in special tortuous blood vessels and the plasticity of the tip. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the structure of the microcatheter provided in the embodiments of this application; Figure 2 This is a three-dimensional schematic diagram of an embodiment of the present application showing an enhancement region and a reduction region in the intermediate layer; Figure 3 This is a schematic diagram illustrating the setting of enhancement and reduction regions in the intermediate layer according to an embodiment of this application; Figure 4 A schematic diagram showing the location of the opening interval provided in an embodiment of this application; Figure 5 One of the schematic diagrams provided in this application embodiment shows that the density of openings in the first interval is greater than the density of openings in the second interval; Figure 6 This is a second schematic diagram illustrating that the density of openings in the first interval is greater than the density of openings in the second interval, as provided in an embodiment of this application. Figure 7 A schematic diagram showing a braided layer provided on the outer side of the intermediate layer in an embodiment of this application; Figure 8 This is a schematic diagram of a balloon disposed outside the tube body, provided for an embodiment of this application.

[0010] Icons: 1-First baseline; 2-Second baseline; 01-Intermediate layer; 02-Reinforcing rib; 03-Opening; 04-Inner layer; 05-Outer layer; 07-Illuminating ring; 08-Woven layer; 09-Reinforcement zone; 10-Reduction zone; 11-Tube body; 111-Bending control section; 112-Main body section; 12-Connector; 121-First interval; 122-Second interval; 13-Body area; 14-Interval; 15-Pore channel; 16-Balloon. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0012] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0013] The inventors of this application have discovered that existing microcatheters are primarily designed with consideration for support and flexibility in mind. The support of a microcatheter affects its delivery performance; better support allows for easier insertion of the microcatheter into the patient's body, while better flexibility allows for easier bending, enabling the microcatheter to travel along the patient's blood vessels.

[0014] Existing microcatheter structures make the support and flexibility of microcatheters closely related; improving the flexibility of a microcatheter requires reducing its support, and it is difficult to achieve both simultaneously. Therefore, it is challenging to achieve good flexibility while maintaining good support.

[0015] Based on this, the inventors of this application provide a microcatheter, such as Figures 1 to 3 As shown, the tube includes a body 11, which comprises an inner layer 04, a middle layer 01, and an outer layer 05. The middle layer 01 includes a reinforcing region 09, a body region 13, and a weakening region 10 arranged sequentially along the circumferential direction of the tube 11, with the bending stiffness of the reinforcing region 09, the body region 13, and the weakening region 10 decreasing sequentially. The circumferential direction includes clockwise and counterclockwise directions. The bending stiffnesses of the reinforcing region 09, the body region 13, and the weakening region 10 are denoted as A3, A2, and A1, respectively, i.e., A3>A2>A1.

[0016] like Figure 3 As shown, in both clockwise and counterclockwise directions, there are reinforcement regions 09, body regions 13 and weakening regions 10 arranged in sequence. The two body regions 13 are located between reinforcement regions 09 and weakening regions 10 in the clockwise and counterclockwise directions, respectively. In this way, reinforcement regions 09 and weakening regions 10 are located on opposite sides of the circumference of the tube body 11, which can coordinate the mechanical properties of both sides, thereby improving the bending performance of the microcatheter.

[0017] This application provides a reinforced region 09 on one side of the tube body 11, which has high bending stiffness, giving the microcatheter good pushing performance and support on the reinforced region 09 side, and preventing excessive bending of the microcatheter from causing kinking. At the same time, the tube body 11 has low bending stiffness on the weakened region 10 side, with high local compliance and good bending performance. In addition, the tube body 11 also includes a body region 13 with stiffness located between the reinforced region 09 and the weakened region 10. The body region 13 maintains the basic stiffness and performance of the tube body 11 and forms a smooth transition between the reinforced region 09 and the weakened region 10, avoiding local stress concentration that could lead to microcatheter bending failure, thereby achieving the passage of the microcatheter in specially tortuous blood vessels and the plasticity of the tip.

[0018] In addition, the tube body 11 also includes a body region 13 with stiffness located between the reinforcement region 09 and the weakening region 10. The body region 13 maintains the basic stiffness and performance of the tube body 11 and forms a smooth transition between the reinforcement region 09 and the weakening region 10, avoiding local stress concentration that could lead to bending failure of the microcatheter.

[0019] In some embodiments, the bending stiffness of the reinforcing region 09, the body region 13, and the weakening region 10 also satisfies 0.7A2≤A1<A2, A2<A3≤1.3A2. In this way, the stiffness of the reinforcing region 09 and the weakening region 10 is controlled within a certain range relative to the body region 13, thereby coordinating the mechanical properties among the three as a whole and ensuring the flexibility of the microcatheter through specially tortuous blood vessels and the distal plasticity.

[0020] In some implementations, such as Figure 1 As shown, the intermediate layer 01 includes a main body segment 112 near the proximal end and a bending control segment 111 near the distal end. The enhancement region 09 extends from the main body segment 112 to the bending control segment 111 and covers the bending control segment 111; the weakening region 10 covers the bending control segment 111.

[0021] It should be noted that in the field of interventional medical devices, the end of a medical device implanted in the human or animal body that is closer to the operator is generally called the "proximal end," and the end that is farther from the operator is called the "distal end." This application defines the "proximal end" and "distal end" of any component of a medical device based on this principle.

[0022] In the above embodiment, the bending control section 111 is the part of the microcatheter that is bent by the operator's manipulation of the distal end of the tube body 11. Since the weakening zone 10 covers the bending control section 111, that is, the entire bending control section 111 is the weakening zone 10, the bending stiffness of the bending control section 111 on the weakening zone 10 side is lower and its flexibility is enhanced, which allows the bending control section 111 to bend easily under the operator's operation. The reinforcing zone 09 extends from the main body section 112 to the bending control section 111 and covers the bending control section 111. This allows both the main body section 112 and the bending control section 111 to have good support. Even if the operator does not cause the bending control section 111 to bend or deform, both the main body section 112 and the bending control section 111 have good pushing performance, avoiding excessive bending of the microcatheter that leads to kinking.

[0023] Furthermore, the weakening zone 10 may be located only in the bending control section 111, or it may cover the bending control section 111 and extend to the main body section 112. In some embodiments, a connector 12 is also connected to the proximal end of the tube body 11 to connect the tube body 11 to a structure such as an operating handle.

[0024] In some implementations, such as Figure 2 and Figure 3 As shown, the intermediate layer 01 includes a spring structure, which includes spring wires. That is, the spring structure is formed by winding the spring wires. In this application, the reinforcing region 09, the body region 13, and the weakening region 10 are all provided with the spring structure. Among them, the reinforcing region 09 has a reinforcing rib 02 on the spring structure. The reinforcing rib 02 extends along the axial direction of the tube body 11 and is fixed to the spring wire. The specific fixing method can be one or more of the following: heat fusion connection, ultrasonic welding, laser welding, or adhesive bonding. In this application, by providing axially extending reinforcing ribs 02 on the spring structure, the area where the spring structure is located becomes the reinforcing region 09. The spring structure forms the reinforcing region 09 by providing reinforcing ribs 02, which greatly improves the support performance and anti-kink properties of the microcatheter in this area.

[0025] See also Figure 2 and Figure 3In the spring structure of the weakening region 10, openings 03 are also provided in the spring wires. Multiple openings 03 extend along the axial direction of the tube body 11. The openings 03 on the spring wires can be formed by laser cutting, cutting the spring wires to create the openings 03. By providing multiple openings 03 on the spring structure, this application makes the area where the spring structure is located a weakening region 10. That is, in this area, the spring structure forms a weakening region 10 by providing openings 03, thereby increasing the flexibility of the microcatheter in the weakening region 10. This achieves enhanced rigidity and support of the intermediate layer 01 on the side where the reinforcing region 09 is located, and reduced rigidity and enhanced flexibility on the side where the weakening region 10 is located, improving the flexibility and tip plasticity of the catheter when passing through tortuous blood vessels.

[0026] See also Figure 2 and Figure 3 A body region 13 is provided between the weakening region 10 and the strengthening region 09. The spring structure corresponding to the body region 13 is not further processed, that is, the spring structure itself is the body region 13. In this application, the stiffness of the body region 13 is between the strengthening region 09 and the weakening region 10. The untreated spring structure in the body region 13 maintains the basic stiffness and performance of the tube 11 and forms a smooth transition between the strengthening region 09 and the weakening region 10, avoiding local stress concentration that could cause the catheter to bend and fail, thereby achieving the overall passage of the microcatheter through the special curved channel.

[0027] This application sets the coiled spring structure as the body region 13, and sets reinforcing ribs 02 and openings 03 on the coiled spring structure on both sides of the body region 13, thereby forming an enhanced region 09 and a weakened region 10, which gives the microcatheter a gradient distribution of stiffness in the circumferential direction. This takes into account the support and flexibility of the microcatheter in special curved channels, and forms a smooth transition between the enhanced region 09 and the weakened region 10, avoiding local stress concentration that could lead to catheter bending failure. This achieves the passage of the microcatheter in special tortuous blood vessels and the plasticity of the tip.

[0028] In some embodiments of this application, both the coiled spring structure and the reinforcing rib 02 are made of metal materials, specifically stainless steel, nickel-titanium alloy, tungsten, titanium alloy, and other metals.

[0029] In other embodiments, the reinforcing rib 02 is made of a polymer material, specifically PTFE (polytetrafluoroethylene), LCP (liquid crystal polymer), POM (polyformaldehyde), PA (polyamide), etc.

[0030] Furthermore, in this application, the reinforcing rib 02 extends from the main body segment 112 to the bending control segment 111 and covers the bending control segment 111. That is, both the main body segment 112 and the bending control segment 111 have reinforcing ribs 02. Along the direction from the main body segment 112 toward the bending control segment 111, the dimension of the reinforcing rib 02 in the circumferential direction of the pipe body 11 gradually decreases, that is, the perimeter of the reinforcing rib 02 gradually decreases. In this embodiment, the dimension of the reinforcing rib 02 in the circumferential direction at the distal end of the pipe body 11 is smaller, resulting in a relatively lower bending stiffness at the distal end of the pipe body 11, so that the bending control segment 111 can bend under the operation of the operator.

[0031] In some embodiments, the dimensions of the reinforcing ribs 02 corresponding to the main body section 112 and the bending control section 111 gradually decrease in the circumferential direction of the tube body 11; in other embodiments, only the circumferential dimensions of the reinforcing ribs 02 of the bending control section 111 may gradually decrease.

[0032] In some implementations, such as Figure 3 and Figure 4 As shown, a body region 13 is provided between the reinforcing region 09 and the weakening region 10 in this application. Therefore, there is a certain angle θ between the reinforcing rib 02 in the reinforcing region 09 and the opening 03 in the weakening region 10, and the angle satisfies 90° ≤ θ ≤ 180°. It can be understood that the center of the reinforcing rib 02 is used as the first reference line 1 for the reinforcing region 09, and the center of the opening 03 is used as the second reference line 2 for the weakening region 10. The angle between the first reference line 1 and the second reference line 2 is the angle θ of this application. Figure 3 As shown, the angle θ between the first reference line 1 of the enhancement region 09 and the second reference line 2 of the reduction region 10 is 180°. In other embodiments, the angle θ can be 90° or 120°. Figure 4 As shown, the position of the enhancement zone 09 is kept fixed, while the position of the opening 03 in the deflection zone 10, i.e., the second baseline 2, can move between the intervals 14. In this way, the enhancement zone 09 and the deflection zone 10 are basically on opposite sides in the circumferential direction of the tube body 11. This ensures that when the microcatheter passes through tortuous blood vessels, the enhancement zone 09 provides support for the inner side of the bend of the tube body 11, and the deflection zone 10 provides flexibility for the outer side of the bend of the tube body 11. The body region 13 acts as a link between the enhancement zone 09 and the deflection zone 10 to achieve a rigid transition, thereby effectively ensuring the effectiveness of the catheter in passing through tortuous blood vessels.

[0033] In some embodiments, the arc length L of the opening 03 of the weakening region 10 along the circumferential direction of the conduit and the radius R of the intermediate layer 01 satisfy: 0 < L ≤ πR. Since the opening 03 in this application is formed by laser cutting, the spring wire only needs to be laser-cut to form a slit to serve as the opening 03 of this application, thus forming the weakening region 10. When L = πR, half of the intermediate layer 01 in the circumferential direction is the weakening region 10. In this embodiment, since L ≤ πR, the size of the opening 03 can be made more reasonable, which can increase the flexibility of the tube 11 without significantly affecting the support of the tube 11.

[0034] In some embodiments, the width of the reinforcing rib 02 is d, and the diameter of the spring wire in the spring structure of the reinforcing region 09 is D, satisfying 1 / 2D ≤ d ≤ 2D. Specifically, d can be 1 / 2D, d=D, d=1.5D, or d=2D. In this embodiment, the width of the reinforcing rib 02 is reasonable, which can increase the support of the tube body 11 without significantly affecting the flexibility of the tube body 11. In the embodiments provided in this application, the cross-section of the reinforcing rib 02 can be circular or rectangular. In the embodiment where the cross-section of the reinforcing rib 02 is circular, the width of the reinforcing rib 02 is d2, which is the diameter of the reinforcing rib 02. In the embodiment where the cross-section of the reinforcing rib 02 is rectangular, the width of the reinforcing rib 02 is d2, which is the width of the rectangular cross-section. The cross-section of the reinforcing rib 02 is the section perpendicular to the extension direction of the reinforcing rib 02.

[0035] In one optional embodiment, the present application defines the included angle θ between the reinforcing rib 02 and the opening 03 as 180°, the arc length L of the opening 03 as D, and the reinforcing rib 02 as a circular metal wire with a diameter of D. Thus, by defining the relative positional relationship between the reinforcing rib 02 and the opening 03, and controlling the size of the opening 03 and the size of the reinforcing rib 02, the supporting function of the reinforcing area 09 and the flexibility of the weakening area 10 are synergistically utilized, thereby improving the overall passability of tortuous blood vessels.

[0036] In some embodiments, the weakening zone 10 includes a first zone 121 near the distal end of the tube body 11 and a second zone 122 near the proximal end of the tube body 11. The density of openings 03 in the first zone 121 is greater than the density of openings 03 in the second zone 122. The density of openings 03 can be understood as the total arc length of multiple openings 03 accumulated per unit length along the axial direction of the tube body 11. Therefore, the greater the density of openings 03, the greater the cumulative total arc length of openings 03 per unit length. This application limits the density of openings 03 near the distal end in the weakening zone 10 of the bending control section 111 to be larger and the density of openings 03 near the proximal end to be smaller, thereby achieving greater flexibility at the distal end than at the proximal end in the weakening zone 10, which facilitates the flexibility of the head end. In the bending control section 111 covered by the weakening zone 10 in the intermediate layer 01, there is a first interval 121 and a second interval 122. The first interval 121 is located at the far end of the bending control section 111, and the second interval 122 is located at the near end of the bending control section 111. Since the density of openings 03 in the first interval 121 is greater than the density of openings 03 in the second interval 122, the bending stiffness of the far end of the bending control section 111 is smaller and the flexibility is greater, making it easier to bend under the operation of the operator. As a result, the bending control section 111 of the pipe body 11 has better controllable bending performance.

[0037] It should be added that the pitch of the coiled spring structure in this application is equal, the coiled spring wires are evenly arranged, and the intermediate layer is the same except for the reinforcing ribs and openings as differentiating features.

[0038] In some embodiments, the density of openings 03 is related to the number of openings 03. For example... Figure 5 As shown, assuming that the width (i.e., arc length L) of each opening 03 is equal, the number of openings 03 in the first interval 121 is greater than the number of openings 03 in the second interval 122, so that the density of openings 03 in the first interval 121 is greater than the density of openings 03 in the second interval 122. Furthermore, there may also be some spring wires in the weakening zone 10 that do not have openings 03.

[0039] In some embodiments, the density of openings 03 is related to the width of openings 03, wherein the width of openings 03 is the arc length L along the circumferential direction of the tube body 11, such as... Figure 6 As shown, the number of openings 03 per unit length in the axial direction of the tube 11 is the same, but the width of the openings 03 in the first interval 121 is greater than the width of the openings 03 in the second interval 122, so that the density of openings 03 in the first interval 121 is greater than the density of openings 03 in the second interval 122. See details. Figure 6The spring coil structure in the weakening zone 10 has a uniform arrangement of openings 03 at intervals, but the width (arc length L) of the opening 03 on the side closer to the distal end of the bending control section 111 is larger, thereby differentiating the flexibility of the bending control section 111 at the proximal and distal ends and improving the performance of the catheter through tortuous blood vessels.

[0040] In some embodiments, each spring wire in the spring structure within the weakening region 10 is provided with an opening 03; such as Figure 8 As shown, multiple openings 03 extend along the axial direction of the tube body 11 to form a perforated channel 15. A balloon is provided at the distal end of the tube body 11, and the inner cavity of the balloon is connected to the perforated channel 15. Therefore, gas or liquid can be filled into the balloon 16 through this channel, and the perforated channel 15 formed by the space of the openings 03 can be reused as a cavity that needs to be additionally set in the microcatheter and is connected to the inner cavity of the balloon. This can greatly reduce the size of the tube body 11 and improve the permeability of the microcatheter.

[0041] It should be noted that the formation of the opening 03 in the weakening zone 10 in this application will cause the conventional coiled spring structure to collapse. Therefore, it is necessary to ensure that the coiled spring wires on both sides of the opening 03 are connected by the reinforcing ribs 02 to avoid collapse.

[0042] The reinforcing rib 02 in the enhanced region 09 of this application can be a single continuous metal wire or multiple metal wires. These multiple metal wires can be arranged either circumferentially or axially along the tube body 11. If the reinforcing rib 02 is set as multiple metal wires arranged axially along the tube body 11, and at least one spring wire exposed between two axially arranged wires is not provided with a reinforcing rib 02, then the weakening region 10 corresponding to the exposed spring wire cannot have an opening 03, thus preventing the collapse of the spring structure. This application, through the synergistic arrangement of the reinforcing rib 02 and the opening 03, effectively improves the flexibility and tip plasticity of the microcatheter when passing through particularly tortuous blood vessels.

[0043] In some embodiments, the tube body 11 includes a radiopaque ring 07 disposed at the distal end of the catheter. The radiopaque ring 07 mainly functions to position the radiopaque and fix the head end of the intermediate layer 01. The radiopaque ring 07 can be a structural component made of biocompatible metal materials such as platinum-iridium alloy (PtIr), gold, or tungsten (Wu), or it can be a structural component made of polymer composite radiopaque material such as PU (polyurethane) or PEEK (polyether ether ketone) with radiopaque fillers (such as barium sulfate or tungsten powder) added.

[0044] In some implementations, such as Figure 7As shown, the tube body 11 also includes a braided layer 08, which is located on the side of the intermediate layer 01 near the outer layer 05. The braided filaments of the braided layer 08 can be polymer materials or metal materials. Polymer materials include aramid, UHMWPE (ultra-high molecular weight polyethylene), LCP (liquid crystal polymer), PA (polyamide), PET (polyethylene glycol terephthalate), etc., while metal materials include stainless steel, nickel-titanium alloy, tungsten, titanium alloy, etc. By covering the intermediate layer 01 with the braided layer 08, the opening 03 of the intermediate layer 01 is less likely to loosen, thus fixing the intermediate layer 01 and improving the pushing and torsional resistance of the tube body 11.

[0045] Furthermore, the method for manufacturing the perforated channel 15 is as follows: First, the intermediate layer 01 connected to the reinforcing rib 02 is fitted onto the inner layer 04 of the tube body 11, and the two are heat-fused together (or glued). Then, a laser is used to break the coiled wire on the opposite side of the reinforcing rib 02 back and forth twice along the axis of the tube body 11, forming a channel. Next, a metal wire narrower than the channel width is selected, and while the surface of the metal wire is coated with medical-grade silicone oil and pressed into the channel, it is braided and fixed. Then, a radiopaque ring 07 is fitted onto the end to hold and fix the braided layer 08 and the intermediate layer 01. Finally, the outer layer 05 of the tube body 11 is fitted and heat-fused. After heat fusion, the metal wire is pulled out, resulting in the tube body 11 with the perforated channel 15. This design of the perforated channel 15 helps to reduce the outer contour wall thickness of the tube body 11 and improves its throughput. Covering the intermediate layer 01 with the braided layer 08 improves the bonding between the opening 03 of the coiled spring and the tube body 11, thus improving the torsion control performance of the tube body 11.

[0046] In the embodiments provided in this application, both the inner layer 04 and the outer layer 05 of the tube body 11 can be made of a soft and highly biocompatible polymer material.

[0047] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A microcatheter, characterized in that, The tube includes an inner layer, an intermediate layer, and an outer layer. The intermediate layer includes a reinforcing region, a body region, and a weakening region arranged sequentially along the circumferential direction of the tube, wherein the bending stiffness of the reinforcing region, the body region, and the weakening region decreases sequentially.

2. The microcatheter according to claim 1, characterized in that, The intermediate layer includes a main body section near the proximal end and a bending control section near the distal end, wherein, The reinforcement zone extends from the main body section to the bending control section and covers the bending control section; The weakening zone covers the bending control section.

3. The microcatheter according to claim 2, characterized in that, The intermediate layer includes a spring structure, which includes spring wires; a reinforcing rib is provided on the spring structure in the reinforcement area, the reinforcing rib extending along the axial direction of the tube and fixed on the spring wires; An opening is provided in the spring wire of the spring structure in the weakening region, and a plurality of the openings extend along the axial direction of the tube body.

4. The microcatheter according to claim 3, characterized in that, The reinforcing rib extends from the main body section to the bending control section and covers the bending control section. Along the direction from the main body section to the bending control section, at least a portion of the reinforcing ribs gradually decrease in size in the circumferential direction of the tube body.

5. The microcatheter according to claim 3, characterized in that, In the circumferential direction of the tube, the included angle θ between the reinforcing rib and the opening satisfies: 90° ≤ θ ≤ 180°.

6. The microcatheter according to claim 3, characterized in that, The arc length L of the opening along the circumferential direction of the tube and the radius R of the intermediate layer satisfy: 0 < L ≤ πR; and / or, The width d of the reinforcing rib and the diameter D of the coiled wire satisfy: 1 / 2D≤d≤2D.

7. The microcatheter according to claim 3, characterized in that, The weakening zone includes a first interval near the distal end of the tube and a second interval near the proximal end of the tube, wherein the density of the openings in the first interval is greater than the density of the openings in the second interval.

8. The microcatheter according to claim 7, characterized in that, The plurality of openings includes a first opening disposed in the first interval and a second opening disposed in the second interval; wherein, The width of the first opening is greater than the width of the second opening; and / or, The number of the first openings is greater than the number of the second openings.

9. The microcatheter according to claim 3, characterized in that, Each spring wire in the spring structure in the weakening region is provided with an opening, and the plurality of openings extend along the axial direction of the tube body to form a hole channel; A balloon is provided at the distal end of the tube, and the inner cavity of the balloon is connected to the orifice.

10. The microcatheter according to any one of claims 1-9, characterized in that, The tube body further includes a braided layer, which is located on the side of the intermediate layer near the outer layer; and / or, The bending stiffnesses of the enhanced region, the body region, and the weakened region are A3, A2, and A1, respectively, satisfying: 0.7A2≤A1<A2, A2<A3≤1.3A2.

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