microcatheter

Abstract

The present application relates to a kind of microcatheter, including catheter body, the catheter body includes tube body and the conical head end in the distal end of tube body, the tube body includes the inner layer pipe, intermediate pipe and outer layer pipe in turn from inside to outside, the inner layer pipe and outer layer pipe are made of high molecular material, the intermediate pipe is made of metal material, and the number of intermediate pipe is multiple.The microcatheter of the present application has better twist control and supporting property, effectively enhances the ability of microcatheter to deal with complex lesions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, and in particular to a microcatheter for assisting in the placement and exchange of guide wires. BACKGROUND

[0002] Percutaneous Coronary Intervention (PCI) is mainly used for the treatment of obstructive coronary artery disease, and has developed rapidly due to its minimally invasive, time-saving, safe and efficient advantages. According to statistics, the number of PCI surgeries in China in 2020 reached 1.224 million, 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 success rate and good efficacy for conditions such as left main disease, Chronic Total Occlusion (CTO) disease, and severe calcification disease.

[0003] As a microcatheter suitable for assisting in the placement and exchange of guide wires in peripheral and coronary blood vessels, as well as the injection of contrast agents, embolization or therapeutic agents, it is the first choice for various coronary artery diseases targeted by PCI. In PCI surgery, about 15% are chronic total occlusion diseases, and almost every CTO surgery requires the use of a microcatheter. The technical requirements for microcatheters in clinical practice are good support, twist control, pushability, and head-end crossing. However, the twist control of current microcatheters is relatively poor, and there are also problems of insufficient support and pushability, leading to prolonged surgery time or surgery failure. In addition, the microcatheter head has a large resistance when passing through the guide catheter or blood vessel, which may cause damage to the guide catheter or blood vessel, and the crossing is also not good. In addition, the design of the proximal end of the microcatheter is not comfortable and convenient for medical personnel to operate, affecting the efficiency of the surgery.

[0004] It should be noted that the information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a microcatheter to solve at least one technical problem existing in the current microcatheter products.

[0006] To achieve the above object, the present application provides a micro catheter, comprising a catheter body, the catheter body comprising a tube body and a tapered head end at the distal end of the tube body, the tube body comprising an inner tube, an intermediate tube and an outer tube which are sequentially sleeved from inside to outside, the inner tube and the outer tube are made of high polymer material, the intermediate tube is made of metal material, and the number of the intermediate tube is multiple.

[0007] In an embodiment, a guide wire cavity is arranged in the tapered head end and the tube body, the guide wire cavity in the tapered head end communicates with the guide wire cavity in the tube body, and the guide wire cavity in the tapered head end is arranged eccentrically with the guide wire cavity in the tube body.

[0008] In an embodiment, the outer peripheral surface of the tapered head end is coaxially arranged with the outer peripheral surface of the tube body, the guide wire cavity in the tapered head end is arranged eccentrically with the outer peripheral surface of the tapered head end, or the outer peripheral surface of the tapered head end is arranged eccentrically with the outer peripheral surface of the tube body, and the guide wire cavity in the tapered head end is concentrically arranged on the outer peripheral surface of the tapered head end.

[0009] In an embodiment, the offset distance between the guide wire cavity in the tapered head end and the guide wire cavity in the tube body is 0.04mm-0.06mm.

[0010] In an embodiment, the outer shape of the tapered head end is a non-linear taper, and / or a spiral body is arranged on the outer peripheral surface of the tapered head end, the spiral body is spirally wound on the outer peripheral surface along the axial direction of the tapered head end.

[0011] In an embodiment, a wire is spirally wound on the outer peripheral surface of the outer tube along the axial direction.

[0012] In an embodiment, the tapered head end has at least one of the following characteristics:

[0013] The edge of the tapered head end is provided with a lubricating coating;

[0014] The edge of the tapered head end is provided with a rounded corner;

[0015] The edge of the tapered head end is wrapped with a gel type protective film;

[0016] At least one of the inner surface and the outer surface of the tapered head end is provided with an endothelialization coating.

[0017] In an embodiment, the intermediate tube is a coiled spring tube and / or a braided tube.

[0018] In an embodiment, all the intermediate tubes include at least one coiled spring tube and one braided tube.

[0019] In an embodiment, the intermediate tube is made of a nickel-titanium alloy material.

[0020] In an embodiment, the microcatheter further comprises a connector matching the natural shape of the hand, and the proximal end of the tube body is connected to the connector.

[0021] In an embodiment, the connector is provided with a groove for holding the hand, and the groove is provided with an anti-skid structure.

[0022] The microcatheter provided by the application has at least the following beneficial effects:

[0023] The microcatheter of the application is provided with a plurality of intermediate tubes made of metal materials between the inner tube and the outer tube, so that the torsion control performance of the microcatheter of the application is greatly improved, and the support performance is also improved. For some complex lesion surgeries, the improvement of torsion control performance and support performance greatly enhances the ability of the microcatheter to cope with complex lesions. Therefore, the microcatheter of the application can realize effective crossing of tortuous and spastic blood vessels, shorten the operation time, reduce the operation cost, solve the pain of patients and other effects, and meet different treatment needs. BRIEF DESCRIPTION OF DRAWINGS

[0024] Those skilled in the art will understand that the provided drawings are for better understanding of the application and do not constitute any limitation on the scope of the application. In the drawings:

[0025] Figure 1 is a schematic view of the overall structure of the microcatheter in the embodiment of the application;

[0026] Figure 2 is an axial cross-sectional view of the tube body of the microcatheter in the embodiment of the application;

[0027] Figure 3 is a schematic view of the structure of the linear taper of the tapered head end in the embodiment of the application;

[0028] Figure 4 is a schematic view of the structure of the non-linear taper of the tapered head end in the embodiment of the application;

[0029] Figure 5 is a schematic view of the structure of the spiral body wound on the outer peripheral surface of the tapered head end in the embodiment of the application;

[0030] Figure 6 is a schematic view of the structure of the wire wound in a spiral on the outer peripheral surface of the outer tube of the tube body in the embodiment of the application;

[0031] Figure 7is a structure schematic view of eccentric arrangement of the tapered head end and the tube body in the embodiment of the present application, wherein the outer circumferential surface of the tapered head end is coaxial with the outer circumferential surface of the tube body, and the guide wire cavity in the tapered head end is coaxial with the outer circumferential surface of the tapered head end;

[0032] Figure 8 is a structure schematic view of eccentric arrangement of the tapered head end and the tube body in the embodiment of the present application, wherein the outer circumferential surface of the tapered head end is coaxial with the outer circumferential surface of the tube body, and the guide wire cavity in the tapered head end is coaxial with the outer circumferential surface of the tapered head end;

[0033] Figure 9 is an application scenario graph of the guide wire passing through and being placed in one of the branch blood vessels when the tapered head end and the tube body are eccentrically arranged in the embodiment of the present application;

[0034] Figure 10 is an application scenario graph of the guide wire passing through and being placed in another branch blood vessel after the eccentrically arranged tapered head end of the rotating microcatheter is rotated in the embodiment of the present application;

[0035] Figure 11 is a transverse sectional view of the tube body in the embodiment of the present application, wherein the coil tube is wound by a plurality of wire materials;

[0036] Figure 12 is a side view of the connecting piece in the embodiment of the present application;

[0037] Figure 13 is a front view of the connecting piece in the embodiment of the present application;

[0038] Figure 14 is a test result graph of the microcatheter overall pushing force value in the embodiment of the present application, and the vertical coordinate is the pushing force value (unit: gf);

[0039] Figure 15 is a test result graph of the microcatheter distal end rotation angle in the embodiment of the present application, and the vertical coordinate is the distal end rotation angle (unit: °);

[0040] Figure 16 is a test result graph of the support force value reached by the tapered head end in the embodiment of the present application, and the vertical coordinate is the support force value (unit: N), and the horizontal coordinate is the measurement position (unit: mm) from the distal end surface of the tapered head end;

[0041] Figure 17 is a test result graph of the crossing property reached by the tapered head end in the embodiment of the present application, and the vertical coordinate is the lesion length (unit: mm).

[0042] Among them, the reference signs are:

[0043] 1-catheter body; 11-head end; 111-helix; 112-guide wire lumen; 12-shaft; 121-inner tube; 122-intermediate tube; 122a-coiled spring tube; 122b-braided tube; 123-outer tube; 124-coiled wire; 2-connector; 21-groove; 22-anti-skid structure; 20-guide wire; 30-branch vessel. DETAILED DESCRIPTION

[0044] The present application will be further described with reference to the drawings and specific embodiments. The advantages and features of the present application will become apparent to those skilled in the art upon examination of the following detailed description. It is to be understood that the drawings are designed solely for purposes of illustration to facilitate the understanding of the present application. Therefore, specific dimensions, directions, and other physical characteristics relating to the drawings are not to be considered limiting. It is to be understood that the application disclosed herein is susceptible to broad field of utility and application. Consequently, functions and / or arrangements of the parts according to the principles of the present application, can be employed as within the true scope of the application and their equivalents. Accordingly, any measures intended for limiting the scope of the application are not to be understood as limiting. It is to be understood that the application disclosed herein is susceptible to broad field of utility and application. Consequently, functions and / or arrangements of the parts according to the principles of the present application, can be employed as within the true scope of the application and their equivalents. Accordingly, any measures intended for limiting the scope of the application are not to be understood as limiting.

[0045] It is to be understood that the terms such as first and second, etc., are used herein solely to distinguish one from another without necessarily implying the existence of a relationship or order between them. Also, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more limitations, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0046] Moreover, in the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. The illustrative expressions of the above terms in the present specification do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction. In addition, in the following description, "axial" and "circumferential" are used for ease of description; "axial" refers to the direction along the central axis of the microcatheter, that is, the longitudinal direction; "circumferential" refers to the direction around the central axis of the microcatheter.

[0047] The core idea of the present application is to provide a microcatheter that can be used to assist the placement and exchange of guide wires in peripheral and coronary blood vessels, and also can be used for microcatheters for injecting contrast agents, embolization or therapeutic agents. Preferably, the microcatheter of the present application is suitable for percutaneous coronary intervention.

[0048] The microcatheter of the present application has better pushability, supportability, twist control and crossing ability compared to existing microcatheter products, effectively enhancing the ability of the microcatheter to deal with complex lesions. In the intervention of vascular treatment, the microcatheter of the present application can be sent into the target lumen through the guide catheter, and by virtue of its good performance, it can realize the operation of guide wire placement and exchange, etc., and provide a foundation for subsequent operation.

[0049] The technical solutions of the present application are further described below in combination with the drawings and preferred embodiments, and the embodiments described below and the features in the embodiments can be supplemented or combined with each other without conflict.

[0050] Please refer to Figure 1 , which schematically shows the overall structure of the microcatheter provided by an embodiment of the present application. As Figure 1 shown, the microcatheter described in the present embodiment has a guide wire lumen through the axial direction of the microcatheter, and the guide wire lumen is used to pass the guide wire.

[0051] The microcatheter described in the embodiment comprises a catheter body 1. The catheter body 1 comprises a tapered head end 11 and a tube body 12. The tapered head end 11 is arranged at the distal end of the tube body 12 and is fixedly connected with the tube body 12. The tapered head end 11 and the tube body 12 can be integrally formed or separately formed. Preferably, the tapered head end 11 and the tube body 12 are integrally formed to ensure the connection strength of the two. The tube body 12 serves to ensure the supportability, twist controllability and pushability of the microcatheter as a whole. The tapered head end 11 serves to ensure the crossing ability of the distal end of the microcatheter and the selectivity of the vascular positioning. The tapered head end 11 and the tube body 12 jointly ensure the use performance of the microcatheter as a whole.

[0052] As shown in Figure 2 In order to take into account the supportability, twist controllability and pushability of the tube body 12, the tube body 12 is configured to comprise an inner layer tube 121, an intermediate tube 122 and an outer layer tube 123 which are sequentially sleeved from inside to outside. The number of the intermediate tube 122 is multiple, such as 2 or more than 2, preferably 2-3. All the intermediate tubes 122 are also sequentially sleeved. The structures of all the intermediate tubes 122 can be the same or different, and the same structure is understood as the same or different in structure and / or material.

[0053] The inner layer tube 121 and the outer layer tube 123 are both made of a high molecular material, which can be various high molecular materials, and is particularly preferably made of a high molecular material with good biocompatibility and lubricity. Considering that the outer layer tube 123 directly contacts with the blood vessel or the guide catheter, the outer layer tube 123 needs to have a certain strength to ensure its compression resistance. The high molecular material used to prepare the outer layer tube 123 is selected from high molecular materials with high strength, including but not limited to Pebax (block polyether amide), TPU (thermoplastic polyurethane elastomer) and the like, and the outer layer tube 123 can be prepared by using one or more combinations of high molecular materials. Since the inner wall of the inner layer tube 121 (i.e. the cavity wall of the guide wire cavity) directly contacts with the guide wire, the inner wall of the inner layer tube 121 needs to have good lubricity to reduce the friction when it contacts with the guide wire. The high molecular material used to prepare the inner layer tube 121 is selected from high molecular materials with good lubricity, including but not limited to PTFE (polytetrafluoroethylene), PVC (polyvinyl chloride), Pebax (block polyether amide), HDPE (high density polyethylene) and Nylon (nylon) and the like, and the inner layer tube 121 can be prepared by using one or more combinations of high molecular materials.

[0054] Each intermediate tube 122 is made of a metal material, which can be various medical metal materials, and preferably made of a metal elastic material. The metal material for making the intermediate tube 122 includes but is not limited to stainless steel and nickel-titanium alloy. In the embodiment, a metal material with good strength and elasticity such as stainless steel and nickel-titanium alloy can be selected to ensure the flexibility of the microcatheter as a whole, and one or more metal materials can be combined to make each intermediate tube 122. The arrangement of multiple intermediate tubes 122 can greatly improve the torque control performance and support performance of the microcatheter as a whole. At the same time, the inner tube 121 can improve the passability of the guide wire and reduce the resistance when the guide wire passes through. In combination with the outer tube 123, the pushability of the microcatheter in the guide catheter or blood vessel is improved, and the push resistance of the microcatheter is reduced. The intermediate tube 122 can be a coiled tube or a braided tube, or a combination of a coiled tube and a braided tube.

[0055] All intermediate tubes 122 can be coiled tubes. All intermediate tubes 122 can also be braided tubes. Alternatively, at least one of the intermediate tubes 122 is a coiled tube, and at least one of the intermediate tubes 122 is a braided tube. Preferably, at least one braided tube and one coiled tube are included in all intermediate tubes 122, at which time the support, pushability and torque control of the tube body 12 are better. Compared with the coiled tube, the braided tube has better support, pushability and torque control. The combination of the coiled tube and the braided tube can effectively improve the torque control, support and pushability of the microcatheter. It can be understood that the coiled tube is spirally wound by a primary wire material. The braided tube is braided by a primary wire material. The primary wire material can be a round wire or a flat wire or any suitable wire structure.

[0056] After such arrangement, the torque control performance of the microcatheter of the application as a whole is greatly improved, and its support performance is also improved. For some complex lesion surgeries it faces, the improvement of torque control and support greatly enhances the ability of the microcatheter to cope with complex lesions. The microcatheter of the application can effectively cross the tortuous and spastic blood vessels, shorten the operation time, reduce the operation cost, solve the pain of patients and achieve many effects, and meet different treatment needs.

[0057] It should be understood that the axial length of the tapered head end 11 can be changed according to needs.

[0058] As Figure 3As shown in some embodiments, the outer profile of the tapered tip 11 is linearly tapered, i.e. the generatrix of the tapered tip 11 is a straight line. In this case, the tapered tip 11 has a constant taper. When the outer profile of the tapered tip 11 is linearly tapered, the axial length of the tapered tip 11 can be 0.5mm-10.0mm, and the taper can be 0.175-0.195. The taper is determined according to the axial length and the outer diameter of the tapered tip 11. The taper here refers to the ratio of half the difference between the diameters of the distal end face and the proximal end face of the tapered tip 11 to the axial length of the tapered tip 11.

[0059] As shown in some embodiments, the outer profile of the tapered tip 11 is linearly tapered, i.e. the generatrix of the tapered tip 11 is a straight line. In this case, the tapered tip 11 has a constant taper. When the outer profile of the tapered tip 11 is linearly tapered, the axial length of the tapered tip 11 can be 0.5mm-10.0mm, and the taper can be 0.175-0.195. The taper is determined according to the axial length and the outer diameter of the tapered tip 11. The taper here refers to the ratio of half the difference between the diameters of the distal end face and the proximal end face of the tapered tip 11 to the axial length of the tapered tip 11. Figure 4 As shown in some embodiments, the outer profile of the tapered tip 11 is linearly tapered, i.e. the generatrix of the tapered tip 11 is a straight line. In this case, the tapered tip 11 has a constant taper. When the outer profile of the tapered tip 11 is linearly tapered, the axial length of the tapered tip 11 can be 0.5mm-10.0mm, and the taper can be 0.175-0.195. The taper is determined according to the axial length and the outer diameter of the tapered tip 11. The taper here refers to the ratio of half the difference between the diameters of the distal end face and the proximal end face of the tapered tip 11 to the axial length of the tapered tip 11.

[0060] The dimensions (taper, outer diameter, axial length) of the tapered tip 11 should be set according to the size of the guide catheter and the vessel to be intervened, to ensure that the tapered tip 11 can achieve the most suitable guiding performance. The overall length of the tapered tip 11 can also be adjusted according to the taper, to achieve improved guiding performance while ensuring the continuity and integrity of the tapered tip 11 and the tube body 12. For example, the maximum outer diameter of the tapered tip 11 (i.e. the proximal end outer diameter) can be 0.4mm-0.6mm, more preferably 0.4mm-0.5mm, which can effectively improve the push-through performance. Compared with the prior art, the outer diameter of the tapered tip 11 of the present application can be set smaller, with better guiding performance, allowing the microcatheter to pass through narrow blood vessels smoothly.

[0061] As shown in some embodiments, the outer profile of the tapered tip 11 is linearly tapered, i.e. the generatrix of the tapered tip 11 is a straight line. In this case, the tapered tip 11 has a constant taper. When the outer profile of the tapered tip 11 is linearly tapered, the axial length of the tapered tip 11 can be 0.5mm-10.0mm, and the taper can be 0.175-0.195. The taper is determined according to the axial length and the outer diameter of the tapered tip 11. The taper here refers to the ratio of half the difference between the diameters of the distal end face and the proximal end face of the tapered tip 11 to the axial length of the tapered tip 11. Figure 5As shown, in an embodiment, the outer circumferential surface of the tapered head end 11 is provided with a helix 111, which is helically wound along the axial direction of the tapered head end 11 on the outer circumferential surface of the tapered head end 11. At this time, the tapered head end 11 is integrally or integrally formed, that is, when the tapered head end 11 is processed and manufactured, the helix 111 is processed on the outer circumferential surface. The tapered head end 11 can also be formed in parts, that is, the helix 111 is helically wound on the tapered head end 11 which has been processed. If the tapered head end 11 and the helix 111 are formed in parts, the helix 111 needs to be additionally wound around the tapered head end 11 and fixed. If the tapered head end 11 and the helix 111 are integrally or integrally formed, no additional assembly is required, simplifying the manufacturing process. The pitch of the helix 111 can be 5.0mm-9.0mm. The outer diameter of the helix 111 is slightly larger than the outer diameter of the tube body 12, for example, the outer diameter of the helix 111 is 0.05mm-0.2mm larger than the outer diameter of the tube body 12. Alternatively, the outer diameter of the helix 111 is the same as the outer diameter of the tube body 12. The tapered head end 11 with the helix 111 not only increases the penetration and pushing performance, but also helps the microcatheter adjust the advancing mode in the guide catheter or blood vessel to change the pushing mode to the twisting mode. This advancing mode is relatively more gentle and can better adapt to the characteristics of the tortuous coronary blood vessels, which is beneficial to adapt to the advancing of blood vessels of different shapes and tortuous directions. Not only is the pushing performance good, but it is also easier to pass through the tortuous blood vessels. In addition, compared with the assembly of the helix 111 and the tapered head end 11 formed in parts, the probability of the helix 111 and the tapered head end 11 falling off due to insecure fixation in the blood vessel is reduced.

[0062] As shown, Figure 6 In an embodiment, the outer circumferential surface of the outer layer tube 123 is helically wound with a wire 124 along the axial direction, and the wire 124 is wound on the outer circumferential surface of the outer layer tube 123 to form a helical structure. The wire diameter of the wire 124 can be 0.05mm-0.2mm, and the pitch is 2-8 times the wire diameter. The advantage of such arrangement is that the axial pushing of the microcatheter can be twisted and pushed, increasing the adhesion of the microcatheter to blood vessels of different tortuosity and reducing the damage of the microcatheter to the blood vessels. The material of the wire 124 can be a high-strength polymer material or a metal material. The outer circumferential surface of the entire length or part of the length of the outer layer tube 123 is wound with the wire 124. Therefore, the arrangement of the wire 124 increases the performance of the microcatheter in the operation of twist control and twist pushing. The polymer material for preparing the wire 124 can be at least one of polyester, polyamide, polyvinyl chloride and nylon elastomer. The metal material for preparing the wire 124 can be stainless steel, nickel-titanium alloy or other metal alloy material, and one or more metal materials can be combined to prepare the wire 124.

[0063] In some embodiments, the tapered tip 11 is configured to be a catheter and vessel friendly structure, which is the first to enter the catheter or vessel, and therefore, the tapered tip 11 needs to have good guidance, low friction coefficient and moderate hardness when entering the catheter or vessel.

[0064] In an embodiment, the edges (including mainly the proximal edge and / or the distal edge) of the tapered tip 11 are provided with a lubricating coating. The lubricating coating can be coated with PVP (polyvinylpyrrolidone), PTFE (polytetrafluoroethylene), paclitaxel, etc., so as to coat the edges of the tapered tip 11 with the lubricating coating. The lubricating coating can reduce the friction between the tapered tip 11 and the vessel or catheter, reduce the sharpness of the edges of the tapered tip 11, reduce the damage of the device to the vessel wall, and improve the safety and success probability of the operation.

[0065] In an embodiment, the edges of the tapered tip 11 are configured in a smooth structure rather than a sharp structure, and the smooth structure is usually a rounded corner. For example, the proximal edge (the junction with the tube body 12) of the tapered tip 11 is rounded, and the distal edge of the tapered tip 11 is also rounded.

[0066] In an embodiment, the edges of the tapered tip 11 are wrapped with a gel type protective film to increase the introduction of the microcatheter. The protective film can be made of a biological grade gel plastic material, which is a smooth wrapping shape to wrap the sharp edges of the tapered tip 11.

[0067] The guide wire lumen is provided in the tapered tip 11 and the tube body 12, and the guide wire lumen 112 in the tapered tip 11 communicates with the guide wire lumen in the tube body 12. Preferably, the guide wire lumen 112 in the tapered tip 11 is eccentrically arranged with the guide wire lumen in the tube body 12, i.e. the central axis of the guide wire lumen 112 in the tapered tip 11 does not coincide with the central axis of the guide wire lumen in the tube body 12, which can be seen in detail from Figures 7 to 9 . In this way, the torsion of the tapered tip 11 and the selectivity and positioning of the blood vessel direction are improved, so that the microcatheter can be more accurately and quickly aligned with the target lumen (such as a branch blood vessel or a main blood vessel) during the operation, reducing the difficulty of the operation, reducing the risk coefficient of the operation, and improving the safety of the operation. It can be understood that the eccentric arrangement can improve the torsion of the tapered tip 11, and the selectivity of the blood vessel direction can also be achieved by designing different eccentric degrees, which is important for the positioning of the diseased blood vessel.

[0068] The offset distance between the guide wire lumen 112 in the tapered head 11 and the guide wire lumen in the tube body 12 is preferably 0.04mm-0.06mm. With this arrangement, the guide wire lumen 112 in the tapered head 11 is reduced, and the guide wire still has a small offset to meet the 0.014" guide wire crossing requirement. Due to the limitation of the outer diameter of the guide wire to be crossed, too large offset distance will result in a small inner diameter of the tapered head 11 (the inner diameter of the guide wire lumen 112), which makes the guide wire unable to pass through, and too small offset distance will result in insufficient guide wire offset and offset angle to meet the requirement of entering different angle bifurcated blood vessels.

[0069] As shown in Figure 7 , in an embodiment, the outer peripheral surface of the tapered head 11 is coaxially arranged with the outer peripheral surface of the tube body 12, and the guide wire lumen 112 in the tapered head 11 is eccentrically arranged with the outer peripheral surface of the tapered head 11. At this time, the outer peripheral surface of the tapered head 11 is coaxial with the outer peripheral surface of the tube body 12, and the guide wire lumen 112 in the tapered head 11 is eccentric with the outer peripheral surface of the tapered head 11.

[0070] As shown in Figure 8 , in another embodiment, the outer peripheral surface of the tapered head 11 is eccentrically arranged with the outer peripheral surface of the tube body 12, and the guide wire lumen 112 in the tapered head 11 is concentrically arranged with the outer peripheral surface of the tapered head 11. In this scheme, the outer peripheral surface of the tapered head 11 is non-coaxial with the outer peripheral surface of the tube body 12, and the guide wire lumen 112 in the tapered head 11 is coaxial with the outer peripheral surface of the tapered head 11.

[0071] Figure 7 Compared with Figure 8 , Figure 7 , the outer profile of the tapered head 11 is more vascular friendly, and the probability of damage to it is smaller, and Figure 8 , the tapered head 11 has better guide wire guiding performance.

[0072] The embodiment is shown in Figure 7 . As shown in Figure 9 and Figure 10 , for bifurcated blood vessels, the guide wire 20 is placed in the guide wire lumen of the microcatheter, and the distal end of the guide wire 20 extends from the distal end of the guide wire lumen 112 of the tapered head 11. As shown in Figure 9 , first, the distal end of the guide wire 20 is placed in one of the branch blood vessels 30, and further, the microcatheter can be rotated at the proximal end, which can change the orientation of the outlet of the guide wire lumen 112 of the tapered head 11, that is, the guide wire 20 can be controlled to enter another branch blood vessel 30. This structure can change the advancing direction of the distal end of the guide wire 20, and accurately position the diseased blood vessel.

[0073] The tapered tip 11 can be a double-layer or multi-layer composite structure, so that the tapered tip 11 as a whole has a suitable hardness, ensuring the support and softness of the tapered tip 11. The double-layer or multi-layer composite structure described herein refers to that the tapered tip 11 itself is composed of double-layer or multi-layer tubes.

[0074] As the first foreign part to contact the blood, the tapered tip 11 should have better biocompatibility, and preferably has an endothelialization coating on the inner and outer surfaces of the tapered tip 11 to facilitate endothelialization and prevent blood clotting on the surface. The material of the endothelialization coating can be, for example, heparin, clopidogrel bisulfate, aspirin, or a combination of one or more materials, to prevent platelet aggregation and blood clotting.

[0075] The tube body 12 should have a large proximal stiffness and a small distal stiffness to ensure the pushability and softness of the microcatheter as a whole. To this end, the intermediate tube 122 can be designed to have a large proximal stiffness and a small distal stiffness, for example, the stiffness decreases from the proximal end to the distal end of the intermediate tube 122, and the way of decreasing the stiffness is not limited. In specific implementation, for example, the pitch of the coiled tube is adjusted to change the stiffness of the intermediate tube 122, the sparser the coiled tube is, the smaller the stiffness is, and the tighter the coiled tube is, the greater the stiffness is. Further, different pitches can be set for different sections of the tube body 12 in the axial direction. For another example, the braid density of the braided tube is adjusted to change the stiffness of the intermediate tube 122, the greater the braid density is, the smaller the stiffness is, and the smaller the braid density is, the greater the stiffness is. Different braid densities can also be set for different sections of the tube body 12 in the axial direction. The braid density is the number of crossings per inch, abbreviated as PPI. In addition, increasing the number of wire materials of the coiled tube can also improve the support force of the microcatheter, that is, a coiled tube formed by coiling multiple wire materials is used as the intermediate tube 122. And / or, increasing the number of wire materials of the braided tube can also improve the support force of the microcatheter, that is, a braided tube formed by twisting multiple wire materials together is used as the intermediate tube 122.

[0076] Generally, the pitch of the coiled tube is not more than 2 times the wire diameter of the wire material. If the pitch of the coiled tube is more than 2 times the wire diameter, the supportability of the microcatheter as a whole will be greatly affected, and the supportability will be reduced. The number of wire materials in the coiled tube can be 1 to 11. Within this range, the coiled tube can provide better torque control force, and the hardness of the microcatheter as a whole can be controlled within a suitable range. If it exceeds, the hardness may be too high, resulting in a loss of overall flexibility.

[0077] In an embodiment, the braided density of the braided tube can be 100 PPI to 250 PPI. If the braided density exceeds 250 PPI, the overall stiffness of the microcatheter will be reduced, which is not conducive to pushing and braiding stability in the process. If the braided density is less than 100 PPI, the overall stiffness of the microcatheter will be increased, which is easy to cause damage to the guide catheter or blood vessel, and at the same time, the tracking performance of the catheter to the guide wire will be reduced.

[0078] As shown in Figure 2 and Figure 11 , in a specific embodiment, the tube body 12 includes an outer tube 123, two intermediate tubes 122 and an inner tube 121; the wall thickness of the inner tube 121 is 0.015mm to 0.03mm, and preferably the inner tube 121 is a PTFE tube material; if the wall thickness of the inner tube 121 is too small, less than 0.015mm to 0.03mm, when the guide wire is used or exchanged multiple times, the inner tube 121 is too thin and easy to wear, which can cause the guide wire to be exposed, causing the microcatheter lumen to be blocked, which not only damages the overall performance of the microcatheter, but also affects the passing and use of the guide wire inside the microcatheter. If the wall thickness of the inner tube 121 is too large, under the condition that the overall outer diameter of the microcatheter is required, the thickness of the metal layer (i.e. the intermediate tube 122) will be compressed, which will result in insufficient support and torque control of the microcatheter, and at the same time, the thickness of the outer tube 123 will be compressed, which will cause the outer tube 123 to have the risk of exposing the outer wall of the guide wire, and cause greater damage to the blood vessel wall.

[0079] As an example, the wall thickness of the outer tube 123 is 0.1mm to 0.25mm; the total wall thickness of the two intermediate tubes 122 is 0.03mm to 0.09mm; one of the intermediate tubes 122 is a braided tube, and the other is a coiled spring tube. Further, as shown in Figure 11 , one of the two intermediate tubes 122 is a coiled spring tube 122a, and the other is a braided tube 122b, and the coiled spring tube 122a is made of two wires. At this time, increasing the number of wires of the coiled spring tube 122a can not only ensure the stability of the overall pitch of the coiled spring tube 122a, but also make the torque control and support of the microcatheter better. It should be noted that when facing complex lesions, better catheter support and manipulation torque control are the key conditions for a successful operation, therefore, the microcatheter of the present application has good torque control and support, which can make the operation more accurate and reliable, and improve the success rate of the operation.

[0080] As shown in Figure 1 , the microcatheter involved in the present embodiment also includes an ergonomic connector 2, i.e. the outer shape of the connector 2 is designed to match the natural shape of the hand. The proximal end of the tube body 12 is connected to the connector 2. The connector 2 can be used by the operator to hold and operate the microcatheter. Since the connector 2 is designed in an ergonomic manner, the comfort and convenience of the medical staff when operating the microcatheter can be improved.

[0081] As shown in Figure 12 and Figure 13 According to the shape of the finger and the holding posture, the recess 21 can be arranged on the connecting piece 2, the recess 21 can be arranged continuously along the circumference of the connecting piece 2, or can be arranged symmetrically and spaced along the circumference of the connecting piece 2. Preferably, the groove surface of the recess 21 is provided with anti-skid structure 22 to increase the friction, and the anti-skid structure 22 can be one or a combination of structures such as: convex points, depressions, anti-skid coating, etc. The anti-skid structure 22 increases the friction when the finger contacts the connecting piece 2, prevents the microcatheter from slipping out of the operator's hand, and reduces the safety risk in the operation. The connecting piece 2 can also be arranged to have a certain mechanical linkage with the tube body 12, such as rotating the connecting piece 2, which can rotate the microcatheter to change the orientation of the tapered head end 11 of the guide wire lumen 112, thereby controlling the advancing direction of the microcatheter or the extension direction of the guide wire.

[0082] Further, the microcatheter in the embodiment and the comparative example product are compared and analyzed in terms of pushability, twist control, flexibility and crossing ability. Specifically, the microcatheter sample with a double-layer intermediate tube of braiding and spring winding is compared with the microcatheter sample with only one layer of braiding intermediate tube and the microcatheter sample with only one layer of tightly wound spring intermediate tube, to illustrate the advantages of the microcatheter product provided by the embodiment in crossing ability, twist control, head end support and head end crossing ability.

[0083] pushing and withdrawing performance test method, the microcatheter is pushed through the vascular model plate in a 37℃ water bath with the help of the guide catheter in the pushing device, and the experiment is performed at the same and constant pushing speed and pushing distance. The number of samples in each of the three groups of samples is 10, each sample is tested once, and the maximum pushing force value in the pushing and withdrawing process is compared. The greater the pushing force value, the greater the pushing resistance and the poorer the pushability. In addition, the torque control property is tested by the "catheter torque control rotation performance test method". The distal end of the microcatheter is fixed to an angle disc scale card containing a sensor, and the proximal end of the microcatheter is fixed to a rotary motor. The proximal end is set to rotate at the same and constant rotational speed for the same number of revolutions, and the rotational angle of the distal end is recorded after the microcatheter is rotated. The number of samples in each of the three groups of samples is 10, each sample is tested once, and the closer the rotational angle of the distal end of the microcatheter to the rotational angle of the proximal end, the better the torque control property. In addition, the support property of the tapered head end is tested by the "three-point bending" test method. A universal testing machine is used to press the center point of the catheter segment with a fixed span length at the same and constant pressing speed for the same distance, and the maximum bending force value in the process is recorded. The greater the bending force value, the better the support property. Similarly, the number of samples in each of the three groups of samples is 10, and each sample is tested at every 5cm from the top end of the tapered head end. Furthermore, the crossing performance of the tapered head end is also tested. The head end crossing performance is tested in a simulated vascular occlusive lesion model. The proximal end is rotated at the same speed, the number of revolutions is constant at 3, the pushing distance is 5mm, and the advancing distance of the tapered head end 11 in the occlusive lesion is measured and recorded. The closer the distance to the proximal end pushing distance, the better the head end crossing performance. The number of samples in each of the two groups of samples is 10, and each sample is tested once.

[0084] As shown in Figures 14 to 17 , A1 represents the product of the present application, which adopts a double-layer intermediate tube of a braided tube and a coiled spring tube, A2 represents comparative product one, which adopts a single intermediate tube of a braided tube, A3 represents comparative product two, which adopts a single metal tube of a coiled spring tube, A4 represents a smooth tapered head end, and A5 represents a tapered head end with a spiral body.

[0085] As shown in Figure 14 , in terms of pushability, the pushing force value of comparative product two A3 is 24.6gf, the pushing force value of comparative product one A2 is 3.83gf, and the pushing force value of the product of the present application A1 is 2gf. The experimental results prove that the pushing performance of the product of the present application is more excellent, which is reduced by about 91.9% compared with the pushing force value of comparative product two, and is reduced by about 47.8% compared with the pushing force value of comparative product one, so the improvement of the pushing performance is more significant. Then, from Figure 14The provided test data comparison chart shows that the average push force value of the microcatheter sample with the woven spring double-layer structure is significantly lower than that of the other two structures, significantly improving the push performance of the microcatheter.

[0086] As shown in Figure 15 , in terms of twist control, when the proximal end of the microcatheter is rotated by 720°, the rotation angle of the distal end of the microcatheter is recorded as the value of the ordinate. Among them, the distal end twist angle of comparative product two A3 is 648.5°, the distal end twist angle of comparative product one A2 is 707°, and the distal end twist angle of the product of the present application A1 is 710°. The experimental results prove that the twist control performance of the product of the present application is more excellent, compared with the twist angle of comparative product two, which increases by about 9.4%, and compared with the twist angle of comparative product one, which increases by about 0.4%. Therefore, from Figure 15 the provided test data comparison chart shows that the distal end rotation angle of the microcatheter sample with the woven spring double structure is closer to the proximal end rotation angle than the other two structures, indicating that the twist control performance has been significantly improved.

[0087] As shown in Figure 16 , in terms of head end support, the conical head end 11 is set to 30mm long, and the positions of 15mm, 20mm, 25mm and 30mm from the distal end face of the conical head end 11 are measured respectively, and it is found that the support force value that can be borne by comparative product two A3 is significantly lower than comparative product one A2 and the product of the present application A1, and the head end support force value of the product of the present application A1 is greater than that of comparative product one A2. The greater the support force value, the better the bending resistance performance. Therefore, from Figure 16 the provided test data comparison chart shows that at the positions of 15-30cm from the distal end face of the conical head end 11, the microcatheter sample with the woven spring double structure has higher head end support than the other two structures, and can better cross the lesion.

[0088] As shown in Figure 17 , in terms of head end crossing lesion, a 10mm long lesion area is simulated, A4 represents a smooth conical head end, and A5 represents a conical head end with a spiral structure. The experimental results prove that the crossing performance of the conical head end with a spiral A5 is better than that of the smooth conical head end A4, the crossing distance of the smooth conical head end A4 is 2mm, and the crossing distance of the conical head end with a spiral A5 is 5mm, the crossing performance is improved by 150%. From Figure 17 the provided test data chart shows that the conical head end 11 with a spiral or a spiral structure can better cross the occlusive lesion by drilling, so the head end crossing performance is better.

[0089] To sum up, the intermediate pipes 122 made of metal material are arranged between the inner pipe 121 and the outer pipe 123, so that the torsion control performance of the micro catheter is greatly improved, and the support performance is also improved. For some complex lesion surgeries, the improvement of the torsion control performance and the support performance greatly enhances the ability of the micro catheter to cope with the complex lesion. The micro catheter can realize effective crossing of tortuous and spastic blood vessels, shorten the operation time, reduce the operation cost, solve the pain of patients and other effects, and meet different treatment requirements.

[0090] It should be noted that, for those skilled in the art, some improvements and supplements can be made without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application. For those skilled in the art, some slight changes, modifications and equivalent changes made by using the disclosed technical content without departing from the spirit and scope of the present application are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above-mentioned embodiments according to the essential technology of the present application are still within the scope of the technical solutions of the present application.

Claims

1. A microcatheter, comprising: The catheter body comprises a tube body and a tapered head end at the distal end of the tube body, the tube body comprises an inner tube, an intermediate tube and an outer tube which are sequentially sleeved from inside to outside, the inner tube and the outer tube are made of high polymer material, the intermediate tube is made of metal material, the number of the intermediate tube is multiple, the guide wire cavity is arranged in the tapered head end and the tube body, the guide wire cavity in the tapered head end is in communication with the guide wire cavity in the tube body, and the guide wire cavities in the tapered head end and the tube body are eccentrically arranged; The outer peripheral surface of the tapered head end is coaxially arranged with the outer peripheral surface of the tube body, the guide wire cavity in the tapered head end is eccentrically arranged with the outer peripheral surface of the tapered head end, or the outer peripheral surface of the tapered head end is eccentrically arranged with the outer peripheral surface of the tube body, and the guide wire cavity in the tapered head end is concentrically arranged with the outer peripheral surface of the tapered head end; The diameter of the guide wire cavity of the tapered head end decreases along the guide wire outlet direction; the guide wire cavity of the tapered head end has a cross section at the guide wire outlet; the axis formed by passing the center of the cross section along the extension direction of the tube body is parallel to and does not overlap with the axis of the guide wire cavity of the tube body; the axis passing through the guide wire cavity of the tapered head end is formed inside the guide wire cavity of the tapered head end.

2. The microcatheter of claim 1, wherein, The offset distance between the guide wire cavity in the tapered head end and the guide wire cavity in the tube body is 0.04mm-0.06mm.

3. The microcatheter of claim 1, wherein, The outer shape of the tapered head end is a nonlinear taper, and / or a spiral body is arranged on the outer peripheral surface of the tapered head end, which is spirally wound on the outer peripheral surface along the axial direction of the tapered head end.

4. The microcatheter of claim 1, wherein, The outer peripheral surface of the outer tube is spirally wound with a wire along the axial direction.

5. The microcatheter of claim 1, wherein, The tapered head end has at least one of the following characteristics: The edge of the tapered head end is provided with a lubricating coating; The edge of the tapered head end is provided with a rounded corner; The edge of the tapered head end is wrapped with a gel type protective film; At least one of the inner surface and the outer surface of the tapered head end is provided with an endothelialization coating.

6. The microcatheter of claim 1, wherein, The intermediate tube is a coiled spring tube and / or a braided tube.

7. The microcatheter of claim 6, wherein, At least one of the coiled spring tube and the braided tube is included in all the intermediate tubes.

8. The microcatheter of claim 6, wherein, The intermediate tube is made of nickel-titanium alloy material.

9. The microcatheter of claim 1, wherein, A connecting piece matching the natural shape of the hand is further included, and the proximal end of the tube body is connected with the connecting piece.

10. The microcatheter of claim 9, wherein, The connecting piece is provided with a groove for holding the hand, and the groove is provided with an anti-slip structure.

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