Microcatheter

Abstract

The utility model provides a microcatheter which comprises a catheter body, the catheter body comprises an inner layer, a middle layer and an outer layer which are sequentially overlapped in a sleeved mode, the middle layer comprises a braid layer and a spring winding layer which are arranged from the near end to the far end in the axial direction of the catheter body, the far end of the braid layer is connected with the near end of the spring winding layer, the outer layer wraps all the braid layer, and the outer layer wraps part or all the spring winding layer. At least part of the length section of the spring winding layer is provided with a developing part. By means of the configuration, the manufacturing process of the microcatheter is simplified, the developing effect of the head end of the microcatheter is improved, and the overall outer diameter of the microcatheter is not increased.

Description

Technical Field

[0001] The utility model relates to the technical field of medical equipment, in particular to a micro-catheter. Background Art

[0002] Percutaneous coronary intervention (PCI) is mainly used to treat obstructive coronary artery disease. It has developed rapidly due to its advantages of minimal trauma, time saving, safety and high efficiency. According to statistics, the number of PCI surgeries in China reached 1.224 million in 2020, with a compound annual growth rate of 16.3%, and the market size of PCI-related interventional devices has reached 6.9 billion yuan. In addition, PCI has a high surgical success rate and good therapeutic effect for left main trunk lesions, chronic total occlusion (CTO) lesions, and severely calcified lesions.

[0003] Microcatheters are used in peripheral and coronary vessels to assist in guidewire placement and exchange, as well as to inject contrast agents, embolization or therapeutic agents. They are the first choice for various coronary artery lesions targeted by PCI. About 15% of PCI surgeries are chronic total occlusions (CTOs), and microcatheters are required for almost every CTO surgery. However, the main problems with existing microcatheters are as follows:

[0004] (1) In order to ensure the torsion control and support of the microcatheter, a multi-layer composite structure is designed, and the number of intermediate layers is 2 or 3. This type of structure is not only complex in process, but also increases the outer diameter of the microcatheter, and has poor passability in some narrow and tortuous blood vessels;

[0005] (2) The imaging performance of the microcatheter is achieved by adding a developing ring to the tip, which not only has a poor imaging effect but also increases the outer diameter of the distal end of the microcatheter.

[0006] Therefore, for those skilled in the art, how to design a micro-catheter that can simplify the process, increase the development effect, and not increase the outer diameter is a technical problem that urgently needs to be solved.

[0007] It should be noted that the information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Utility Model Content

[0008] The utility model aims to provide a micro-catheter, aiming to simplify the manufacturing process of the micro-catheter, increase the head end development effect thereof, and do not increase the overall outer diameter of the catheter.

[0009] To achieve the above-mentioned purpose, the utility model provides a microcatheter, including a tube body, wherein the tube body includes an inner layer, an intermediate layer and an outer layer stacked in sequence, the intermediate layer includes a braided layer and a spring layer arranged along the axial direction of the tube body from the proximal end to the distal end, the distal end of the braided layer is connected to the proximal end of the spring layer, the outer layer covers the entire braided layer, the outer layer covers part or all of the spring layer, and at least a partial length section of the spring layer is provided with a developing portion.

[0010] Optionally, a portion of the length of the coiled spring layer is provided with the drug portion, and the remaining portion or the entire length of the coiled spring layer is provided with the developing portion.

[0011] Optionally, the length segment provided with the drug portion is located at the distal end of the spring layer and exposed outside the distal end of the outer layer, and the length segment provided with the developing portion is located at the proximal end of the spring layer.

[0012] Optionally, the length section provided with the developing section is a surface-modified structure, or the length section other than the length section provided with the drug section and the developing section is a surface-modified structure.

[0013] Optionally, the microcatheter further includes a tapered head end, which is disposed at the distal end of the tube body, and the length segment provided with the drug portion is disposed at the proximal end of the tapered head end without covering the tapered head end, or the length segment provided with the drug portion covers the tapered head end.

[0014] Optionally, the length of the spring layer is 10% to 30% of the total length of the microcatheter.

[0015] Optionally, at least a partial length section of the spring winding layer is a surface modified structure, and the length section provided with the developing portion is the same as or different from the length section provided with the surface modified structure.

[0016] Optionally, the length segment provided with the developing portion is located at the distal end of the spring winding layer, and the length segment provided with the surface modification structure is located at the proximal end of the spring winding layer.

[0017] Optionally, the spring pitch at the proximal end of the spring winding layer is smaller than the spring pitch at the distal end of the spring winding layer, and the length segment at the proximal end of the spring winding layer is a surface modified structure, and the length segment at the distal end of the spring winding layer is provided with the developing portion.

[0018] Optionally, the braided layers have the same braiding density or different braiding densities.

[0019] Optionally, the developing part is a coating structure and covers the surface of the spring wire for preparing the spring winding layer.

[0020] Optionally, the spring winding layer is formed by winding at least one of a metal spring wire and a polymer spring wire.

[0021] As described above, the microcatheter provided by the utility model includes: a tube body, the tube body includes an inner layer, an intermediate layer and an outer layer stacked in sequence, the intermediate layer includes a braided layer and a spring layer arranged along the axial direction of the tube body from the proximal end to the distal end, the distal end of the braided layer is connected to the proximal end of the spring layer, the outer layer covers all of the braided layer, the outer layer covers part or all of the spring layer, and at least part of the length of the spring layer is provided with a developing portion. With such a configuration, the tube body of the microcatheter of the utility model only uses a single-layer intermediate layer instead of a non-multi-layer composite structure, which simplifies the manufacturing process of the microcatheter and does not increase the overall outer diameter of the microcatheter. The utility model does not add a developing ring at the distal end of the outer layer, but sets a developing portion at least part of the length of the spring layer, thereby adjusting the developing position and increasing the developing area, so that the developing effect of the distal end of the catheter is better, improving the overall developing performance of the microcatheter, and avoiding increasing the outer diameter of the distal end of the catheter due to development. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Those skilled in the art will appreciate that the drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0023] Figure 1 1 is a schematic diagram of the structure of a microcatheter provided by the present invention according to an embodiment, in which the outer layer is not shown and only the inner layer structure of the conical head end is shown;

[0024] Figure 2 This is a schematic diagram of the structure of a hollow coil spring provided by the utility model according to an embodiment;

[0025] Figure 3 It is a partial structural schematic diagram of a microcatheter provided by the utility model according to an embodiment, wherein the outer layer is shown as a cutaway figure;

[0026] Figure 4 1 is a schematic diagram of a partial structure of a microcatheter provided according to another embodiment of the present invention, wherein the entire coil spring layer is covered by an outer layer, and the conical head end is exposed outside the distal end of the coil spring;

[0027] Figure 5 It is a partial structural schematic diagram of a microcatheter provided according to another embodiment of the present invention, wherein the conical tip is coated with a polymer spring.

[0028] In the attached figure:

[0029] 10-inner layer; 20-middle layer; 21-braided layer; 22-spring layer; 2201-first length segment; 2202-second length segment; 30-outer layer; 40-conical head; 220-hollow spring; 221-support ring; 50-developing part; 60-drug part. DETAILED DESCRIPTION

[0030] In order to make the purpose, advantages and features of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0031] As used in the present invention, the singular forms "one", "an", "one" and "the" include plural objects, the term "or" is usually used to include the meaning of "and / or", the term "several" is usually used to include the meaning of "at least one", and the term "at least two" is usually used to include the meaning of "two or more". In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" as well as "proximal end" and "distal end" generally refer to two corresponding parts, which include not only endpoints. In addition, as used in the present invention, "installed", "connected", "connected", and one element "set" on another element should be understood in a broad sense, usually only indicating that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements can be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element can be in any orientation such as inside, outside, above, below or one side of another element, unless the content clearly indicates otherwise. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances. In addition, directional terms such as above, below, up, down, upward, downward, left, right, etc. are used relative to the exemplary embodiments as shown in the figures, with the upward or upper direction toward the top of the corresponding figure, and the downward or lower direction toward the bottom of the corresponding figure.

[0032] The "proximal end" mentioned in this application document refers to the end that is closer to the operator when in use, and the "distal end" refers to the end that is farther from the operator when in use; the "axial" mentioned generally refers to the direction of the microcatheter along its own axis, the "radial" generally refers to the direction of the microcatheter perpendicular to its axial direction, and the "circumferential" generally refers to the direction around the axial direction of the microcatheter. In addition, the "length segment" mentioned should be understood as the size and shape of the outer contour defined by the winding of the spring wire.

[0033] The purpose of this application is to provide a microcatheter to solve the problems of complex process, large outer diameter and poor imaging effect of existing microcatheters. It should be noted that this application does not include improvements to the method itself, and the surface modification methods involved are all known methods.

[0034] The following description is given in conjunction with the accompanying drawings.

[0035] See also Figure 1 to Figure 5 The present application provides a microcatheter, which includes a tube body, wherein the tube body includes an inner layer 10, an intermediate layer 20 and an outer layer 30 which are stacked in sequence, that is, the intermediate layer 20 is sleeved on the inner layer 10, and the outer layer 30 is sleeved on the intermediate layer 20. The tube body is used to ensure the overall support, twist control and pushing performance of the microcatheter.

[0036] The inner layer 10 and the outer layer 30 are both made of polymer materials, which can be various existing polymer materials, and polymer materials with good biocompatibility and good lubricity are preferably selected. The inner layer 10 is the inner tube, and the outer layer 30 is the outer tube. The inner layer 10 needs to pass through the guide wire, and its inner surface must ensure good lubrication performance to reduce the friction when it contacts the guide wire, so as to increase the passability of the guide wire and reduce the resistance when the guide wire passes. In some embodiments, the inner layer 10 is made of materials such as but not limited to PTFE (polytetrafluoroethylene), PVC (polyvinyl chloride), Pebax (block polyether amide), HDPE (high-density polyethylene) and Nylon (nylon) and their combinations. The outer layer 30 can improve the pushability of the microcatheter in the guide catheter or blood vessel, reduce the push resistance of the microcatheter, and avoid the metal material of the middle layer 20 directly exposed to damage the blood vessel. Since the outer layer 30 directly contacts the blood vessel or the guide catheter, the outer layer 30 should have a higher compressive strength. In some embodiments, the outer layer 30 is made of a material such as, but not limited to, Pebax (block polyetheramide), TPU (thermoplastic polyurethane elastomer), and the like, and combinations thereof.

[0037] The middle layer 20 is used to improve the torsion control performance and support performance of the entire microcatheter. In the present application, the middle layer 20 is a single-layer structure (i.e., a single layer), replacing the existing structure of multiple middle layers. For more details, see Figure 1As shown, the middle layer 20 includes a braided layer 21 and a spring layer 22 arranged along the axial direction of the tube body from the proximal end to the distal end, and the distal end of the braided layer 21 is connected to the proximal end of the spring layer 22. The braided layer 21 and the spring layer 22 are both coated on the inner layer 10, the outer layer 30 covers the entire braided layer 21, and the outer layer 30 covers part or all of the spring layer 22. It should be understood that if part of the structure of the spring layer 22 is not covered by the outer layer 30, the exposed structure of the spring layer 22 should be a polymer material instead of a metal material. Based on this, the braided layer 21 and the spring layer 22 are both single-layer structures, which not only simplifies the manufacturing process of the microcatheter, but also does not increase the outer diameter of the microcatheter, and has better passability for some narrow and tortuous blood vessels.

[0038] Preferably, the length of the coiled spring layer 22 is 10% to 30% of the total length of the microcatheter; designing the coiled spring layer 22 according to this length can provide better torsion control for the distal end of the catheter.

[0039] The braided layer 21 can provide strong support for the microcatheter and improve the passability and pushability of the microcatheter. The braided layer 21 is cross-woven by multiple metal braided wires. The braided wires are preferably selected from shape memory alloys and metal materials with good elasticity, including but not limited to stainless steel, nickel-titanium alloys, etc. and combinations thereof. The braided wires can have various shapes, such as round or flat or other shapes, which are not limited to this. During preparation, the braided layer 21 can be formed by weaving on the inner tube (i.e., the inner layer 10) of the nested liner core through a braiding machine. The braided layer 21 has the same braiding density as a whole, or the braiding density of the braided layer 21 is different. The larger the braiding density, the tighter the braiding; the smaller the braiding density, the sparser the braiding, and the better the support performance. Preferably, the braiding density of the distal end of the braided layer 21 is greater than the braiding density of the proximal end of the braided layer 21, so that the proximal end of the braided layer 21 has stronger support performance than the distal end.

[0040] The spring layer 22 is spiral. The spring layer 22 can increase the torsion control performance of the microcatheter during operation, and has better torsion control performance than the microcatheter with a completely braided structure. The spring layer 22 is wound by at least one of a metal spring wire and a polymer spring wire. That is, the spring layer 22 can be made by winding a single metal spring wire as a whole or in sections, or the spring layer 22 is made by winding a single polymer spring wire as a whole or in sections, or the spring layer 22 is composed of a combination of metal springs and polymer springs. Generally, the metal spring is arranged at the proximal end to provide a strong support force, and the polymer spring is arranged at the distal end to ensure the torsion control performance. The material of the polymer spring wire includes but is not limited to materials such as polyester, polyamide, polyvinyl chloride and nylon elastomer or a combination thereof. The material of the metal spring wire includes but is not limited to materials such as stainless steel (such as SUS304), nickel-titanium alloy, cobalt-chromium alloy or a combination thereof. Any kind of spring wire can include various shape designs, such as round wire, flat wire or other shapes, and this application is not limited to this.

[0041] The preparation process of the coiled spring layer 22 is relatively simple. For example, a coiled spring is directly wound on the inner tube to form the coiled spring layer 22, or a hollow spring 220 is first made and then the hollow spring 220 is inserted into the inner tube. Figure 2 Preferably, the spring wire is first compressed into a hollow spring 220 by a compression spring machine, and then the hollow spring 220 is sleeved on the inner tube with the liner core inserted, and is fitted side by side with the braided layer 21. Further, all the braided wires at one end (i.e., the distal end) of the braided layer 21 are fixed to one end (i.e., the proximal end) of the winding spring layer 220 by welding or bonding, so that the braided layer 21 and the winding spring layer 22 are connected to form a complete whole. The welding method here is not limited. In some embodiments, laser welding is used, but it is not limited to this. It should be understood that the connection between metal materials can be fixed by welding, and the connection between polymer materials and metal materials should be fixed by bonding. After the braided layer 21 and the winding spring layer 22 are connected into a whole, an outer tube is at least sleeved on the outside of the braided layer 21, and then, the inner layer 10, the middle layer 20 and the outer layer 30 are tightly fitted by at least one of heating and pressurizing.

[0042] Continue to see Figure 2 Preferably, the two ends of the spring layer 22 (i.e., the hollow spring 220) are tightly wound support rings 221. The support ring 221 has almost flat ends, which is convenient for welding or bonding the braided wire, and is also convenient for welding or bonding with the conical head end 40, reducing the difficulty of welding or bonding. The spring pitch of the support ring 221 is small, which is basically one time the diameter of the spring wire. The support ring 221 can provide a fixed position for fixing the two ends, and can also play a role in stabilizing the spring layer 22 and improving the supporting performance of the spring layer 22.

[0043] It should be further explained that the material for preparing the tube body is not the focus of this application. Although some materials are listed in the embodiments of this application, technicians in this field can also find other known materials to realize the functions recorded in the tube body of this application or achieve the corresponding effects, not just the materials recorded in this specification.

[0044] In addition, the present application does not install a developing ring at the distal end of the outer layer, but instead sets a developing portion 50 at least in part of the length of the spring layer 22, thereby adjusting the developing position and increasing the developing area, so that the developing effect of the distal end of the catheter is better, improving the overall developing performance of the microcatheter, and avoiding increasing the outer diameter of the distal end of the catheter due to development.

[0045] The developing part 50 is made of a radiopaque developing material, and preferably gold, platinum-iridium alloy, or other material with good developing performance. The developing part 50 can be provided on at least a portion of the length of the spring layer 22 in one or more known ways. That is, the method of providing the developing part 50 can be understood by referring to the prior art, and will not be described in detail in this application.

[0046] For example, the spring wire itself is a developable wire, such as a DFT composite wire, a spring wire containing a developable coating, etc., and the spring wire layer 22 can be developed as a whole by direct winding; or, the developing portion 50 is a coating structure and covers the surface of the spring wire. The present application particularly considers the coating structure to achieve development, which is more flexible and convenient. In more detail, if it is a metal spring, a developable coating structure can be formed on the surface of the spring wire through surface modification methods such as ion plating, chemical plating, vacuum sputtering, plasma immersion ion implantation and deposition, physical vapor deposition, and chemical vapor deposition; if it is a polymer spring, a developable coating structure can be formed on the surface of the spring wire through surface coating processes such as dipping, spraying, and brushing.

[0047] In order to better balance the supporting performance, preferably, at least a portion of the length of the coiled spring layer 22 is a surface modified structure for enhancing the mechanical properties, including strength, stiffness and hardness, so as to improve the supporting performance of the single-layer intermediate layer 20, so that the microcatheter as a whole has good torsion control, support and development properties. The present application obtains the surface modified structure by treating at least a portion of the length of the coiled spring layer 22 using a surface modification method known to those skilled in the art. It should be understood that the length of the coiled spring layer 22 provided with the development portion 50 may be the same as or different from the length of the coiled spring layer 22 being the surface modified structure.

[0048] In one embodiment, the length section of the spring layer 22 having the developing portion 50 is located at the distal end of the spring layer 22 to achieve development at the distal end of the spring layer 22, while the length section of the spring layer 22 having the surface modified structure is located at the proximal end of the spring layer 22, so that the proximal end of the spring layer 22 has stronger supporting performance.

[0049] The spring pitches of the spring layer 22 may be the same or different as a whole. Preferably, the spring pitch of the proximal end of the spring layer 22 is smaller than the spring pitch of the distal end of the spring layer 22; in this way, the support performance of the proximal end of the spring layer 22 can be further improved. Preferably, the spring pitch of the length section of the spring layer 22 that is a surface modified structure is smaller than the spring pitch of the length section of the spring layer 22 that is provided with the developing portion 50. More preferably, the length section of the proximal end of the spring layer 22 is a surface modified structure and has better support performance, while the length section of the distal end of the spring layer 22 is provided with the developing portion 50 to enhance the developing property.

[0050] In an alternative embodiment, the entire length of the spring layer 22 is provided with a developing portion 50, and the entire length is a surface-modified structure. In this case, the developing area is larger and the overall strength is better.

[0051] In order to expand the function of the microcatheter, preferably, a portion of the length of the coiled spring layer 22 is provided with a drug portion 60, and the remaining portion or the entire length of the coiled spring layer 22 is provided with a developing portion 50. In this way, the coiled spring layer 22 can play a developing role and also has a drug delivery function. The length of the coiled spring layer 22 provided with the drug portion 60 is usually exposed to the outside and is not covered by the outer layer 30, so as to facilitate the direct release of the drug into the blood vessel. However, the release of the drug can also be achieved by other means. The present application is not limited to exposing the length of the drug portion 60 to the outside of the outer layer 30, and does not limit the specific function of the drug portion 60, such as including but not limited to anticoagulation, antithrombosis, thrombolysis, etc. or a combination thereof. The drug portion 60 is preferably covered on the surface of the spring wire in the form of a coating.

[0052] Preferably, the length section of the winding spring layer 22 provided with the drug portion 60 is located at the distal end of the winding spring layer 22 and exposed outside the distal end of the outer layer 30, and the length section of the winding spring layer 22 provided with the developing portion 50 is located at the proximal end of the winding spring layer 22. Optionally, the length section of the winding spring layer 22 provided with the developing portion 50 is a surface modified structure, or the length section of the winding spring layer 22 other than the drug portion 60 and the developing portion 50 is a surface modified structure. In this case, the winding spring layer 22 has been subjected to surface modification treatment, and has both drug delivery and developing functions. Preferably, the length section provided with the developing portion 50 corresponds to the length section of the surface modification to avoid increasing the length of the winding spring layer 22.

[0053] Alternatively, the length section of the winding spring layer 22 provided with the drug portion 60 is located at the distal end of the winding spring layer 22, the length section of the winding spring layer 22 provided with the developer portion 50 is located in the middle part of the winding spring layer 22, and the proximal end of the winding spring layer 22 is a surface modification structure. This structural design separates the surface modification and the developer in different length sections, which is conducive to reducing the process difficulty.

[0054] It should also be recognized that the spring layer 22 can be treated by various known surface modification treatment methods, and this application is not limited to this. The surface modification described in this application refers to improving the mechanical properties of the spring layer 22 while maintaining the original properties of the spring layer 22. The mechanical properties include strength, hardness and stiffness. There are many methods for surface modification, such as surface shot peening, surface alloying, surface quenching, ion implantation and ion beam assisted deposition, laser surface treatment, electron beam surface treatment, electric spark surface treatment, etc. Surface modification can be physical method, chemical method, mechanical force surface modification. Specifically, those skilled in the art can refer to the prior art for understanding. In practice, one or more surface modification methods can be used to treat the spring layer 22. It should be understood that the surface modification treatment is mainly for metal springs, and polymer springs are relatively not suitable for enhancing mechanical properties through surface modification. Surface modification methods for metal materials include but are not limited to surface shot peening, surface alloying, etc. or their composite modification. Composite modification refers to the comprehensive use of multiple methods to change the surface properties of metal materials to improve their mechanical properties.

[0055] In addition, both the metal coil spring and the polymer coil spring are suitable for setting the developing part 50 and the drug part 60. It is particularly considered that the developing part 50 is set on the metal coil spring, and the developing effect is better. It is also particularly considered that the drug part 60 is set on the polymer coil spring so that it is directly exposed outside the outer layer 30 for release. The developing part 50 and the drug part 60 can be set on the coil spring by surface coating. Moreover, the surface of the coil spring layer 22 needs to be cleaned after modification and coating to remove impurities caused by these processes. It should be further explained that the braided layer 21 does not need surface treatment.

[0056] Furthermore, the microcatheter of the embodiment of the present application generally further includes a tapered head end 40, which is disposed at the distal end of the tube body and fixedly connected to the tube body. The function of the tapered head end 40 is to ensure the penetrability of the distal end of the microcatheter and the selectivity of blood vessel positioning. The tapered head end 40 and the tube body work together to ensure the overall performance of the microcatheter. The proximal end of the tapered head end 40 is connected to the distal ends of the outer layer 30 and the inner layer 10, and the major diameter of the tapered head end 40 matches the outer diameter of the outer layer 30. The tapered head end 40 may be covered by the spring layer 22 or not. This is described in more detail below.

[0057] See also Figure 3 and Figure 4 In one embodiment, the conical head end 40 is exposed outside the distal end of the spring layer 22 , that is, the distal end of the spring layer 22 does not extend to the conical head 40 .

[0058] Continue to see Figure 3In one example, the spring layer 22 includes a first length segment 2201 and a second length segment 2202 which are connected in sequence along the axial direction from the proximal end to the distal end, and the distal end of the first length segment 2201 is welded and fixed to the proximal end of the second length segment 2202; the first length segment 2201 is the proximal length segment of the spring layer 22, and the second length segment 2202 is the distal length segment of the spring layer 22; the outer layer 30 covers the entire spring layer 22, and the conical head end 40 is exposed outside the distal end of the spring layer 22; the first length segment 2201 and the second length segment 2202 are both wound by metal spring wire; wherein the first length segment 2201 is subjected to surface modification treatments such as surface shot peening and alloying to improve mechanical properties, and the second length segment 2202 is subjected to surface electroplating, vacuum coating, vapor deposition and other common methods to form a developable coating structure (i.e., the developing part 50); in addition, the major diameter of the conical head end 40 matches the outer diameter of the outer layer 3010. Such a configuration enables the proximal end of the coiled spring layer 22 to have a stronger support performance, and the distal end of the coiled spring layer 22 can provide better imaging performance. Preferably, the coiled spring pitch of the first length segment 2201 is smaller than the coiled spring pitch of the second length segment 2202, that is, the first length segment 2201 uses a smaller coiled spring pitch, so that the proximal end of the coiled spring layer 22 has stronger support. Based on this, the microcatheter can not only maintain a high support performance and torque control performance, but also has a stronger head end imaging performance, and the overall outer diameter is smaller, and the passability is better.

[0059] Continue to see Figure 4 In one example, the coil spring layer 22 is composed of a single polymer coil spring or a single metal coil spring, the entire coil spring layer 22 is covered by the outer layer 30, and the tapered tip 40 is exposed outside the distal end of the coil spring layer 22; the entire or partial length of the polymer coil spring or the metal coil spring can be coated on the surface to form a developable coating structure (i.e., the developing portion 50) to improve the overall developing performance of the microcatheter tip.

[0060] See also Figure 5 In another embodiment, the conical head end 40 is wrapped by the coil spring layer 22, that is, the distal end of the coil spring layer 22 further extends to the conical head end 40, which is conducive to setting the drug portion 60 that can be directly exposed to the outside at the distal end of the coil spring layer 22. Figure 5 and Figure 3The difference is that the first length segment 2201 is wound by metal spring wire, and the second length segment 2202 is wound by polymer spring wire, and the distal end of the first length segment 2201 is bonded and fixed to the proximal end of the second length segment 2202; the outer layer 30 covers the entire first length segment 2201, and the second length segment 2202 is completely exposed outside the distal end of the outer layer 30, and the second length segment 2202 covers the conical head end 40, and the shape of the second length segment 2202 is adapted to the taper of the conical head end 40; after the second length segment 2202 is nested in the conical head end 40, it needs to be glued and fixed to the conical head end 40; in addition, the first length segment 2201 is surface-modified to increase its strength, and a developable coating structure is formed by ion plating, vacuum coating, etc., while the surface of the second length segment 2202 forms a drug coating (i.e., the drug portion 60). Therefore, the second length section 2202 is directly exposed to the outside and in contact with the blood vessel, so that the drug on the second length section 2202 can be directly released into the blood vessel during the pushing process of the microcatheter. Preferably, the drug is a thrombolytic drug, which can improve the passability of the microcatheter in the narrowed section of the blood vessel.

[0061] In summary, the microcatheter provided in the embodiment of the present application can provide functions such as auxiliary guidewire placement and exchange in CTO surgery. Combined with the performance required of the microcatheter in the clinical use of CTO surgery, the microcatheter of the present application takes into account the pushing performance, support performance, twist control performance, development performance and penetration performance. Moreover, compared with the prior art, the microcatheter of the present application takes into account the twist control performance, support performance and development performance through a single-layer intermediate layer, which not only simplifies the structure of the microcatheter, optimizes the types of raw materials, reduces the cost of raw materials, but also reduces the overall outer diameter of the microcatheter. In particular, the microcatheter of the present application has better development performance, which helps to provide surgical positioning accuracy.

[0062] It should be noted that the above embodiments can be combined with each other. The above description is only a description of the preferred embodiments of the utility model, and does not limit the scope of the utility model. Any changes and modifications made by ordinary technicians in the field of the utility model based on the above disclosure are within the protection scope of the utility model.

Claims

1. A microcatheter, It is characterized in that The invention comprises a tube body, wherein the tube body comprises an inner layer, an intermediate layer and an outer layer which are stacked in sequence, wherein the intermediate layer comprises a woven layer and a spring layer which are arranged along the axial direction of the tube body from the proximal end to the distal end, wherein the distal end of the woven layer is connected to the proximal end of the spring layer, the outer layer covers the entire woven layer, the outer layer covers part or all of the spring layer, and at least a partial length section of the spring layer is provided with a developing portion.

2. The microcatheter according to claim 1, It is characterized in that A portion of the length of the coiled spring layer is provided with the drug portion, and the remaining portion or the entire length of the coiled spring layer is provided with the developing portion.

3. The microcatheter according to claim 2, It is characterized in that The length section provided with the medicine part is located at the distal end of the coiled spring layer and exposed outside the distal end of the outer layer, and the length section provided with the developing part is located at the proximal end of the coiled spring layer.

4. The microcatheter according to claim 3, It is characterized in that The length section where the developing section is provided is a surface-modified structure, or the length section other than the section where the drug section and the developing section are provided is a surface-modified structure.

5. The microcatheter according to claim 3, It is characterized in that The microcatheter also includes a tapered head end, which is arranged at the distal end of the tube body, and the length section with the drug portion is arranged at the proximal end of the tapered head end without covering the tapered head end, or the length section with the drug portion covers the tapered head end.

6. The microcatheter according to claim 1 or 2, It is characterized in that The length of the coiled spring layer is 10% to 30% of the total length of the micro-catheter.

7. The microcatheter according to claim 1 or 2, It is characterized in that At least a partial length section of the spring layer is a surface modification structure, and the length section provided with the developing portion is the same as or different from the length section provided with the surface modification structure.

8. The microcatheter according to claim 7, It is characterized in that The length section provided with the developing portion is located at the distal end of the spring winding layer, and the length section provided with the surface modification structure is located at the proximal end of the spring winding layer.

9. The microcatheter according to claim 1 or 2, It is characterized in that The spring pitch at the proximal end of the spring winding layer is smaller than the spring pitch at the distal end of the spring winding layer, and the length section at the proximal end of the spring winding layer is a surface modified structure, and the length section at the distal end of the spring winding layer is provided with the developing portion.

10. The microcatheter according to claim 1 or 2, It is characterized in that The braided layers have the same braiding density or different braiding densities.

11. The microcatheter according to claim 1 or 2, It is characterized in that The developing part is a coating structure and covers the surface of the spring wire used to prepare the spring winding layer.

12. The microcatheter according to claim 1 or 2, It is characterized in that The spring winding layer is formed by winding at least one of a metal spring wire and a polymer spring wire.

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