A micro guide wire for complex coronary artery lesions and a preparation method and application thereof

Abstract

The application discloses a micro guide wire for complex coronary artery diseases and a preparation method and application thereof. The micro guide wire prepared by the application comprises, from inside to outside, a composite core wire, a polymer buffer coating layer, a platinum-nickel alloy winding layer, an anti-skid transition primer coating layer and a super-smooth hydrophilic surface layer. The composite core wire is laser welded from stainless steel and molybdenum modified nickel-titanium alloy, and cooperates with a gradually changing taper structure to effectively improve the anti-kinking, shaping retention and fatigue resistance of the guide wire. The hydrophilic surface layer adopts a two-component compound, and lubricity and coating stability are taken into account; the winding layer adopts a segmented variable pitch design, and has full-range developing capacity and gradient mechanical properties. The application solves the problems of traditional guide wires, such as mismatching of rigidity and flexibility, easy peeling of the coating layer and poor passability of complex diseases, and is suitable for interventional surgery of complex coronary artery diseases.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a microguidewire for complex coronary artery lesions, its preparation method, and its application. Background Technology

[0002] Chronic total coronary artery occlusion (CTO) is the most severe and challenging type of coronary artery disease, characterized by severe vascular tortuosity, high degree of calcification, dense fibrous cap of occlusion, and significant variations in vascular course. Percutaneous transluminal coronary intervention (PTCA) is the preferred minimally invasive approach for opening CTO lesions in clinical practice. The PTCA microwire, as the core access device in interventional surgery, plays a crucial role in vascular exploration, lesion puncture, track establishment, and delivery and support of microcatheters and balloon stents. Its flexibility, support, torque transmission, tracking ability, imaging capability, and surface lubrication directly determine the success rate and complication rate of complex coronary CTO procedures.

[0003] Currently, most traditional monofilament PTCA guidewires in China adopt a single alloy integral structure, which cannot simultaneously achieve strong proximal support and extreme distal flexibility. This easily leads to vascular dissection or puncture weakness, significant rebound after tip shaping, large torque transmission loss, poor tracking performance, and prominent navigation deviation issues. Conventional CTO-specific guidewires only use a simple core-wire docking structure without a gradual transition design, resulting in abrupt changes in mechanical properties, large torque synchronization deviation, and insufficient active bending accuracy and response speed to meet the needs of complex lesion operations. Moreover, most are incompatible with long-specification applications in neurovascular procedures.

[0004] Existing guidewires mostly use localized imaging marking at the tip, which cannot achieve full-process visualization, making it difficult to accurately determine the intravascular path under digital subtraction angiography (DSA). At the same time, the products lack sufficient anti-kink and anti-breakage mechanical properties, resulting in high pushing resistance. Conventional hydrophilic coatings have a high coefficient of friction and weak adhesion, making them prone to detachment and damage with repeated pushing, increasing vascular injury and surgical risks. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a microguidewire for complex coronary CTO lesions, its fabrication method, and its applications. This invention presents a novel microguidewire structure and fabrication process that balances dual mechanical properties, precise torque transmission, high-definition imaging throughout the procedure, and high lubrication and durability, making it compatible with multiple interventional scenarios.

[0006] This invention provides a microguidewire for complex coronary artery lesions. The microguidewire comprises, from the inside out, a composite core wire, a polymer buffer coating layer, a platinum-nickel alloy winding layer, an anti-slip transition base layer, and a super-slippery hydrophilic surface layer.

[0007] The composite core wire includes a near-end stainless steel support section and a far-end nickel-titanium alloy compliant section; a continuous and smooth tapered transition structure is formed from the near end to the far end, and the outer surface of the composite core wire is provided with nanoscale concave-convex texture, with an average feature size of 100-500nm.

[0008] The proximal stainless steel support section provides excellent axial pushing force and torsional strength, ensuring that the guidewire does not bend or twist during the pushing process, providing stable support for the device to pass through complex blood vessels; the distal nickel-titanium alloy compliant section utilizes its superelasticity and shape memory properties to conform to the tortuous course of the blood vessel, reducing the risk of damage to the blood vessel wall.

[0009] The continuous and smooth tapered transition effectively disperses the stress on the guidewire during pushing, twisting, and bending, avoiding stress abrupt changes and breakage risks caused by the stepped structure. At the same time, the tapered structure makes the torque transmission from the proximal end to the distal end more uniform, reduces torsional hysteresis, and improves the responsiveness and accuracy of guidewire control.

[0010] Nanoscale textured patterns are created on the outer surface of the composite core wire to form a mechanical interlocking effect through the microstructure, thereby strengthening the interlayer bonding ability and preventing the guide wire from peeling off when it undergoes repeated deformation in complex blood vessels. At the same time, the texture is controlled at the nanoscale to retain the original anti-kink, anti-fatigue and torque transmission properties of the core wire.

[0011] The distal nickel-titanium alloy compliant section is a molybdenum-modified nickel-titanium alloy, with a molybdenum content of 1.0%-2.0% by mass, and the balance being nickel and titanium. Introducing molybdenum into the nickel-titanium alloy refines the alloy grains, optimizes the microstructure, and significantly improves the alloy's anti-kink properties, fatigue resistance, and ductile stability. When the molybdenum content is less than 1.0%, the modification effect is insufficient and cannot significantly improve the anti-kink and fatigue properties of the nickel-titanium alloy. The distal end of the guidewire is prone to kinking and creases during repeated bending, affecting control stability. When the molybdenum content is greater than 2.0%, it leads to a significant increase in the brittleness of the nickel-titanium alloy and a decrease in toughness. The distal end of the guidewire is prone to brittle fracture during severe bending and torsion, reducing safety in use.

[0012] The thickness of the coating layer is 5-10 μm. If it is less than 5 μm, the buffer layer is too thin, and the functions of stress buffering and isolating the metal winding wire from the core wire are ineffective. If it is greater than 10 μm, the overall outer diameter is too large and does not meet the conventional outer diameter specifications of coronary CTO microguidewires.

[0013] The super-lubricating hydrophilic surface layer is composed of two components: a hydrophilic lubricating component and a biofilm-forming component. The hydrophilic lubricating component can quickly adsorb water molecules to form a hydrated layer, significantly reducing the friction coefficient of the guidewire surface and reducing pushing resistance; the biofilm-forming component plays a role in film formation, cross-linking, and enhancing interfacial bonding in the coating, thereby improving the density and mechanical strength of the coating.

[0014] The hydrophilic lubricating component is polyvinylpyrrolidone, and the biofilm-forming component is hyaluronic acid.

[0015] Furthermore, the molybdenum content in the molybdenum-modified nickel-titanium alloy is 1.2%-1.8% by mass.

[0016] Furthermore, the molybdenum-modified nickel-titanium alloy also includes 0.1%-0.3% by mass of niobium (Nb) and / or zirconium (Zr).

[0017] Niobium refines grains and pins grain boundaries, stabilizing the phase transformation of nickel-titanium alloys and improving the material's resistance to kinking and bending fatigue. It also improves the structure of dissimilar metal welding zones and reduces torque transmission deviation. Zirconium refines alloy grains and forms a stable passivation film on the surface, enhancing corrosion resistance in blood environments, inhibiting nickel ion precipitation, and improving biocompatibility and anti-calcification capabilities.

[0018] Furthermore, the polymeric buffer coating layer is a medical-grade flexible thermoplastic polymer material, including one or more of polyether block amide, thermoplastic polyurethane, medical nylon, medical polyethylene, and medical polypropylene.

[0019] Furthermore, the distal winding pitch of the platinum-nickel alloy winding layer is smaller than that of the proximal winding pitch. The larger pitch at the proximal end can ensure the overall support strength and torsional stiffness of the guidewire, while the smaller pitch at the distal end can significantly improve the flexibility, tracking ability and imaging clarity of the guidewire tip. At the same time, the gradient change achieves a soft-hard transition, reducing the risk of vascular wall damage and making it more suitable for precise superselection and passage of complex tortuous lesions.

[0020] Furthermore, the diameter of the platinum-nickel alloy winding wire is gradually changed in segments along the axial direction, and the diameter of the winding wire in the proximal segment is larger than that in the distal segment. By gradually changing the diameter of the winding wire in segments along the axial direction, a differentiated mechanical match is achieved, with strong support at the proximal end and high flexibility at the distal end, while optimizing the uniformity of development throughout the entire process.

[0021] Furthermore, the anti-slip transition undercoat is a medical-grade fluorine-containing low-friction polymer material, preferably polytetrafluoroethylene. On the one hand, the extremely low coefficient of friction of the anti-slip transition undercoat itself can reduce the interfacial friction between the guide wire and the winding layer, reduce internal wear and jamming, and improve torque transmission efficiency. On the other hand, its surface energy properties can serve as an intermediate transition layer, significantly enhancing the bonding force between the subsequent hydrophilic coating and the metal / alloy substrate, preventing the coating from peeling and falling off during repeated friction, while providing basic lubrication and biocompatibility, providing a stable adhesion interface for the outer super-slippery hydrophilic coating.

[0022] The anti-slip transition undercoat features a gradient thickness design along the axial direction, with the proximal end being thinner than the distal end. This thickness gradient matches the gradient trend of the outer super-slip hydrophilic surface layer, forming a dual-layer gradient synergistic structure. This structure significantly enhances the interfacial adhesion of the coating and is specifically adapted to the complex mechanical and frictional conditions at different locations in coronary arteries, representing a synergistic innovation in the coating system.

[0023] Furthermore, the mass ratio of polyvinylpyrrolidone to hyaluronic acid is (65-75):(25-35).

[0024] This invention provides a method for preparing the microguidewire, comprising the following steps:

[0025] S1: Laser coaxial welding is performed on the near end stainless steel wire and molybdenum modified nickel-titanium alloy wire. The welding area and the adjacent heat-affected zone are mirror polished, low temperature stress relief tempering treatment at 180℃-220℃ is performed, and then the whole continuous multi-stage gradual taper grinding is performed. Finally, the nickel-titanium alloy section is subjected to constant temperature shaping heat treatment to obtain composite core wire. S2: A polymer buffer coating layer is wrapped around the outside of the composite core wire; S3: A platinum-nickel alloy wire layer is wound on the outside of the buffer coating layer, and the winding is done in a segmented variable pitch manner; S4: Apply an anti-slip transition base coating to the surface of the platinum-nickel alloy wire winding layer and cure it; S5: A gradient super-slippery hydrophilic surface layer with a thickness greater at the distal end than at the proximal end is formed by dip coating with a polyvinylpyrrolidone and hyaluronic acid compound solution. S6: Fixed-length cutting, appearance and size inspection, cleaning, aseptic packaging, and sterilization with ethylene oxide to obtain the finished product.

[0026] Furthermore, the heat treatment temperature of the nickel-titanium alloy segment is 480-530℃. Heat treatment of nickel-titanium alloy at 480-530℃ can refine the grains, stabilize the phase transformation temperature, and endow the alloy with suitable superelasticity and shape recovery ability, thereby improving its resistance to bending and fatigue. If the temperature is too low, the heat treatment is insufficient and the mechanical properties are poor; if the temperature is too high, the grains are coarse and the material becomes brittle, affecting the flexibility and service life of the guide wire.

[0027] The present invention also provides an application of the aforementioned microguidewire for complex coronary artery lesions in complex coronary interventional procedures.

[0028] In summary, compared with the prior art, the present invention achieves the following technical effects: (1) The present invention uses a composite core wire of stainless steel and molybdenum modified nickel-titanium alloy laser welding, combined with a continuous tapered structure, so that the proximal end of the guidewire has good support and pushing performance, and the distal end has excellent flexibility. It can effectively adapt to complex coronary CTO lesions such as tortuous, calcified, and occluded, and solves the defect that traditional guidewires cannot balance support and flexibility, and greatly improves the interventional passage capability of complex vascular access.

[0029] (2) This invention optimizes the microstructure of nickel-titanium alloy by modifying it with molybdenum, which effectively improves the guidewire’s resistance to kinking, bending fatigue and head shaping, making it less prone to intraoperative rebound and kinking failure. The integrated core wire structure without stress break points can achieve efficient synchronous torque transmission, with small torsional hysteresis and good control and follow-up, significantly improving the operation accuracy and stability of interventional surgery.

[0030] (3) The present invention uses a two-component compound gradient hydrophilic coating of polyvinylpyrrolidone and hyaluronic acid. Compared with the traditional single hydrophilic coating, it has better lubrication performance and significantly improves the film-forming property and interface adhesion of the coating. It can withstand repeated pushing and friction during the operation, effectively avoid coating peeling and failure, and ensure a smooth and safe operation throughout the procedure. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art, and can be purchased from commercially available products. Some raw material information is as follows: 304LVM Medical Grade Stainless Steel Wire: 304LVM, Baosteel Special Steel Medical Division; Platinum-nickel alloy wire: PtNi20, Kunming Mingcheng Platinum Precision Alloy Co., Ltd.; Developed and wound wire: PtW10, Taicang Muxing Biomaterials Co., Ltd.; Medical grade polyether block amide: Pebax 3533 SA 01 MED, Arkema, France; Medical grade PA12 (Nylon 12 cushioning layer): UBESTA 3030JI46, manufactured by Ube Industries, Japan; Medical-grade TPU (thermoplastic polyurethane cushioning layer): Estane 58887, Lubrizol Corporation, USA; PTFE dispersion; Teflon PTFE 30, DuPont, USA; Polyvinylpyrrolidone (PVP): PVP K90, Boai New Open Source Medical Technology Group Co., Ltd.; Sodium hyaluronate: Hyatrue® Medical-grade, Bloomage Biotechnology Co., Ltd.

[0033] Example 1 A material for a microguidewire designed for complex coronary CTO includes the following components: Composite core wire: The proximal end uses 304LVM medical-grade stainless steel, and the distal end uses molybdenum-modified nickel-titanium alloy wire: the mass fraction of molybdenum is 1.5%, and the remaining components are nickel and titanium; Polymer buffer coating: Made of medical-grade polyether block amide (Pebax) material, with a coating wall thickness of 8μm; Platinum-nickel alloy winding layer: Medical-grade platinum-nickel alloy wire is used, and a segmented variable pitch winding structure is adopted, with the distal winding pitch being smaller than the proximal winding pitch. Anti-slip transition base coating: Medical-grade polytetrafluoroethylene emulsion is used as the coating material; Super-slippery hydrophilic layer: made of polyvinylpyrrolidone (PVP) and hyaluronic acid (HA) in a mass ratio of 70:30.

[0034] Its preparation method includes the following steps: S1: 304 stainless steel wire and molybdenum-modified nickel-titanium alloy wire with a molybdenum content of 1.5% are laser coaxially welded into an integrated form. The welding area and the adjacent heat-affected zone are mirror polished and subjected to low-temperature stress-relieving tempering at 200℃. The entire wire is subjected to continuous multi-stage gradual taper grinding to form a smooth taper transition structure. The molybdenum-modified nickel-titanium alloy section is subjected to constant temperature shaping heat treatment at 500℃ to obtain a composite core wire. The outer surface of the composite core wire is processed with 100nm-500nm nanoscale concave-convex texture. S2: A polyether block amide polymer buffer coating layer is uniformly coated on the outside of the composite core wire using a micro-extrusion process; the thickness of the coating layer is 8μm. S3: Platinum-nickel alloy wire is used to be wound in segments with variable pitch on the outside of the buffer coating layer, with dense winding at the far end and sparse winding at the near end, and the end of the guide wire is melt-sealed. S4: Clean and level the surface of the platinum-nickel alloy wire winding layer, apply an anti-slip transition base coating, and cure it in stages with gradient temperature increase; S5: Prepare a PVP and hyaluronic acid compound solution according to a mass ratio of 70:30, and use a controllable dip-coating process to prepare a gradient super-slippery hydrophilic surface layer that is thicker at the distal end and thinner at the proximal end. S6: The finished blank is cut to length, its appearance and size are inspected, and it is ultrasonically cleaned with pure water. After aseptic packaging, it is sterilized with ethylene oxide to obtain the finished microguidewire.

[0035] Example 2 A microguidewire for complex coronary artery CTO differs from Example 1 in that it contains 1.0 wt% Mo, while the other structures, proportions, and processes are the same as in Example 1.

[0036] Example 3 A microguidewire for complex coronary artery CTO differs from Example 1 in that it contains 1.2 wt% Mo, while the other structures, proportions, and processes are the same as in Example 1.

[0037] Example 4 A microguidewire for complex coronary artery CTO differs from Example 1 in that it contains 1.8 wt% Mo, while the other structures, proportions, and processes are the same as in Example 1.

[0038] Example 5 A microguidewire for complex coronary artery CTO differs from Example 1 in that it contains 2.0 wt% Mo, while the rest of the structure, proportions, and process are the same as in Example 1.

[0039] Example 6 A microguidewire for complex coronary artery CTO differs from Example 1 in that the mass ratio of PVP to hyaluronic acid is 65:35, while the rest of the structure, ratio and process are the same as in Example 1.

[0040] Example 7 A microguidewire for complex coronary artery CTO differs from Example 1 in that the mass ratio of PVP to hyaluronic acid is 75:25, while the rest of the structure, ratio and process are the same as in Example 1.

[0041] Example 8 A microguidewire for complex coronary artery CTO differs from Example 1 in that the molybdenum-modified nickel-titanium alloy wire also contains 0.2% Nb.

[0042] Comparative Example 1 A microguidewire for complex coronary artery CTO differs from Example 1 in that the distal core wire in the composite core wire is composed of pure nickel-titanium alloy without molybdenum doping, while the rest of the structure, proportions and processes are the same as in Example 1.

[0043] Comparative Example 2 A microguidewire for complex coronary artery CTO differs from Example 1 in that the hydrophilic coating contains only a single PVP component, while the remaining structure, formulation, and process are the same as in Example 1.

[0044] Comparative Example 3 A microguidewire for complex coronary artery CTO differs from Example 1 in that the core wire has a normal constant diameter and no gradual taper, while the rest of the structure, proportions and processes are the same as in Example 1.

[0045] Test method: (1) Torque transmission deviation test method Test the torque of the intervention guidewire according to YY / T 0450.1 The guidewire is horizontally fixed to a special torque testing fixture, and the proximal end is clamped to keep the guidewire straight and unbiased. The proximal end is rotated 360° at a constant speed, and a high-precision angle sensor collects the actual rotation angle of the distal end. The rotation angle deviation is calculated as |theoretical rotation angle - actual rotation angle|.

[0046] (2) Test method for anti-kink performance Medical guidewire bending resistance tested according to ASTM F2394 Set the bending radius to 3mm, bend the guidewire back and forth along the arc path 100 times, and observe the guidewire visually or under a microscope to see if there are any kinks, creases or breaks.

[0047] (3) Pushing resistance test method A silicone tubing simulating the tortuous shape of human blood vessels (multiple bends, simulating the tortuous shape of coronary arteries) is used. An electronic tension sensor pushes the guidewire at a constant speed, recording the maximum pushing resistance throughout the process, in units of N.

[0048] (4) Test method for axial fracture strength Axial fracture strength of medical catheters tested according to GB / T19614 The universal testing machine holds the two ends of the guide wire in the upper and lower clamps respectively, and stretches it axially at a uniform speed of 50 mm / min. Record the maximum fracture load in N.

[0049] (5) Test method for dynamic friction coefficient of hydrophilic coating According to YY / T1536, the tribological properties of hydrophilic coatings on medical devices are tested. In the wetted state, the dynamic friction coefficient between the coating and the simulated blood vessel silicone contact surface was measured using a flat plate friction coefficient tester.

[0050] (6) Test methods for coating adhesion and push resistance The guidewire was repeatedly inserted and pushed 20 times within the simulated blood vessel silicone channel. The coating surface was then observed using a stereomicroscope to assess whether peeling, flaking, or damage occurred.

[0051] The microguidewires prepared in the above embodiments and comparative examples have a diameter of 0.014 inches (approximately 0.35 mm) and a length of 200 cm. The test results are shown in Table 1.

[0052] Table 1. Test results of the examples and comparative examples

[0053] The performance comparison results of the embodiments and comparative examples of the present invention show that the microguide wire scheme using molybdenum-modified nickel-titanium alloy composite core wire, continuous gradient taper structure, and gradient hydrophilic coating of PVP and hyaluronic acid exhibits significant advantages in torque transmission, anti-kink performance, pushing resistance, structural strength, and coating durability. Comparative Example 1, without molybdenum modification, had a torque transmission deviation of 6.8°, and after 100 bends at a 3mm radius, significant kinking occurred, with an axial fracture strength of only 9.6N. Comparative Example 3, without gradient taper, had a torque transmission deviation as high as 8.2°, and was prone to jamming due to stress concentration during bending. Comparative Example 2, using a single PVP hydrophilic coating, had a pushing resistance as high as 6.7N, a friction coefficient of 0.063, and after 20 reciprocating pushes, the coating showed localized peeling and damage. In comparison, the torque transmission deviation of the various embodiments of the present invention (especially embodiments 1, 3, 4, and 6 with a molybdenum content of 1.2-1.8% and optimized ratio of PVP to hyaluronic acid) is controlled between 3.2° and 3.7°, exhibiting excellent anti-kinking performance, with no kinking or creases after bending, and a stable axial fracture strength of 12.2-12.6N; the pushing resistance is as low as 4.6-5.0N, the coefficient of friction is only 0.036-0.039, and the coating remains intact without peeling after 20 reciprocating pushes, and the performance is further improved after the addition of Nb.

[0054] The microguidewire prepared by this invention has biocompatibility that strictly complies with the GB / T 16886 series of standards for "Biological Evaluation of Medical Devices". It is non-cytotoxic, non-sensitizing, and non-mucosal irritant, with a hemolysis rate of ≤3%. It passes both acute systemic toxicity and cytotoxicity tests. After sterilization with ethylene oxide, it is stable in a sterile state. The product has a shelf life of ≥2 years after sterilization.

[0055] In summary, this invention effectively solves the problems of traditional guidewires, such as difficulty in balancing support and flexibility, sluggish control, easy kinking, and easy coating peeling, by optimizing the mechanical properties of the core wire through molybdenum modification, improving control response through gradual taper, and improving lubrication and durability through a two-component compound hydrophilic coating. The overall performance is significantly better than that of each pair of proportions, and can better meet the clinical needs of interventional surgery for complex coronary artery lesions.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microguidewire for complex coronary artery lesions, characterized in that, The microguidewire comprises, from the inside out, a composite core wire, a polymer buffer coating layer, a platinum-nickel alloy winding layer, an anti-slip transition base coating, and a super-slip hydrophilic surface layer; The composite core wire includes a near-end stainless steel support section and a far-end nickel-titanium alloy compliant section; a continuous and smooth tapered transition structure is formed from the near end to the far end; the outer surface of the composite core wire is provided with nanoscale concave-convex texture. The distal nickel-titanium alloy compliant section is a molybdenum-modified nickel-titanium alloy, with a molybdenum content of 1.0%-2.0% by mass fraction, and the balance being nickel and titanium; The super-slippery hydrophilic surface is composed of two components: a hydrophilic lubricating component and a biofilm-forming component. The hydrophilic lubricating component is polyvinylpyrrolidone, and the biofilm-forming component is hyaluronic acid.

2. The microguidewire according to claim 1, characterized in that, The molybdenum mass fraction in the molybdenum-modified nickel-titanium alloy is 1.2%-1.8%.

3. The microguidewire according to claim 1, characterized in that, The molybdenum-modified nickel-titanium alloy also includes 0.1%-0.3% niobium and / or zirconium by mass.

4. The microguidewire according to claim 1, characterized in that, The polymer buffer coating layer is a medical-grade flexible thermoplastic polymer material, including one or more of polyether block amide, thermoplastic polyurethane, medical nylon, medical polyethylene, and medical polypropylene.

5. The microguidewire according to claim 1, characterized in that, The pitch of the far end of the platinum-nickel alloy winding layer is smaller than that of the near end.

6. The microguidewire according to claim 1, characterized in that, The anti-slip transition base coating is a medical-grade fluorine-containing low-friction polymer material, preferably polytetrafluoroethylene.

7. The microguidewire according to claim 1, characterized in that, The mass ratio of polyvinylpyrrolidone to hyaluronic acid is (65-75):(25-35).

8. A method for preparing the microguidewire according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Laser coaxial welding of near-end stainless steel wire and molybdenum modified nickel-titanium alloy wire is performed. The welding area and adjacent heat-affected zone are mirror-polished, subjected to low-temperature stress-relieving tempering at 180℃-220℃, and then subjected to continuous multi-stage tapered grinding. Subsequently, the nickel-titanium alloy section is subjected to constant temperature shaping heat treatment to obtain composite core wire. S2: A polymer buffer coating layer is wrapped around the outside of the composite core wire; S3: A platinum-nickel alloy wire layer is wound on the outside of the buffer coating layer, and the winding is done in a segmented variable pitch manner; S4: Apply an anti-slip transition base coating to the surface of the platinum-nickel alloy wire winding layer and cure it; S5: A gradient super-slippery hydrophilic surface layer with a thickness greater at the distal end than at the proximal end is formed by dip coating with a polyvinylpyrrolidone and hyaluronic acid compound solution. S6: Fixed-length cutting, appearance and size inspection, cleaning, aseptic packaging, and sterilization with ethylene oxide to obtain the finished product.

9. The method for preparing the microguidewire according to claim 8, characterized in that, The heat treatment temperature of the nickel-titanium alloy section is 480-530℃.

10. The application of the microguidewire for complex coronary lesions as described in any one of claims 1-7 in complex coronary interventional procedures.

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