Hollow microcatheter and preparation method thereof

Abstract

The invention relates to the technical field of medical catheters, in particular to a hollow microcatheter and a preparation method thereof. The catheter comprises a catheter body, an outer layer arranged outside the catheter body and an inner layer arranged in the catheter body, the catheter body comprises a plurality of rigid pipe sections, the rigid pipe sections are tightly attached along an axis, and a movable angle is formed between every two adjacent rigid pipe sections. Each rigid pipe section can move independently, so that the rigid pipe sections can move according to the shape of the inner wall of the sacculus, the bending performance of the sacculus is adapted, the bending angle matched with the sacculus is achieved, the sacculus cannot be jacked up, and due to the fact that each rigid pipe section moves independently, the rigidity of the sacculus is improved. Therefore, each rigid pipe section adapts to the angle of the bent cavity channel where the rigid pipe section is located, and the problem that the adaptive capacity of the micro-catheter is insufficient is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical catheters, in particular to a hollow microcatheter and a preparation method thereof. BACKGROUND

[0002] The microcatheter of a hospital is an extremely precise interventional medical instrument, which plays a key role in cardiovascular, neurovascular, peripheral vascular and tumor intervention surgeries.

[0003] In the prior art, Minimally Invasive Shentong Medical Technology (Shanghai) Co., Ltd. discloses the following patents: Chinese Patent Publication No. CN212016424U discloses a medical balloon, a balloon catheter and a medical device, which solves the problem of poor compliance of the medical balloon to the blood vessel during the process of reaching the lesion site through the curved blood vessel, and specifically discloses a balloon body and a recess formed on the outer surface of the balloon body, which improves the bending performance of the medical balloon and further improves its bending ability to better adapt to the shape of the blood vessel.

[0004] It can be known from the medical balloon, balloon catheter and medical device that the linear medical balloon is sent into the blood vessel through the catheter, and the medical balloon is expanded when it reaches the lesion site.

[0005] The company also discloses a catheter and a delivery device, with publication number CN209679245U, and specifically discloses a catheter, which includes an inner layer, an intermediate layer and an outer layer in sequence from the inside to the outside along the radial direction of the catheter, and the intermediate layer includes a base layer, wherein the intermediate layer includes liquid crystal polymer filaments, although such material has high tensile strength and bending performance, but it is still insufficient compared to improving the bending performance of the medical balloon through the recess, which leads to the catheter "lifting" the balloon wall when facing a sharp turn (for example: acute angle bend) exceeding the design value, causing the balloon wall to form local "wrinkles" or "bumps", and the balloon cannot slide smoothly along the catheter, thereby directly affecting the operation performance of the instrument, causing the physician to need to exert more force to push the balloon forward.

[0006] The more core hidden danger is that it significantly increases the risk of damage to the balloon itself and the blood vessel. SUMMARY

[0007] The purpose of the present application is to provide a hollow microcatheter and a preparation method thereof, to solve the problem that the bending performance of the catheter cannot be adapted to the balloon, resulting in increased difficulty in operation.

[0008] To achieve the above-mentioned purpose, one of the purposes of the present application is to provide a hollow microcatheter, which includes a catheter body, an outer layer arranged outside the catheter body and an inner layer arranged inside the catheter body, and the catheter body at least includes: A plurality of rigid pipe segments, the plurality of rigid pipe segments are arranged closely along an axis, and an activity angle is formed between two adjacent rigid pipe segments; An elastic body arranged between two adjacent rigid pipe segments, used for limiting the size of the activity angle; A first hardness value and a second hardness value, the first hardness value is less than the second hardness value; The hardness value of the rigid pipe segment is between the first hardness value and the second hardness value.

[0009] In the above scheme, the hardness value of the rigid pipe segment is adjusted to be between the first hardness value and the second hardness value, and the first hardness value is the hardness of the inner layer of the medical catheter (<20D), and the second hardness value is the hardness of the intermediate layer of the medical catheter (40D-60D). In this way, the rigid pipe segment itself has the ability to resist flattening and kinking, and does not need to be provided with an intermediate layer (metal / non-metal wire weaving / spiral layer). When the rigid pipe segment is not constrained by the intermediate layer, it can move more flexibly, and the bending performance of the entire microcatheter will not be reduced due to the intermediate layer.

[0010] Further, each rigid pipe segment can move independently, and the rigid pipe segment can move according to the shape of the inner wall of the balloon, so as to adapt to the bending performance of the balloon, reach a bending angle that matches the balloon, and will not lift the balloon. Moreover, since each rigid pipe segment moves independently, it will not affect other rigid pipe segments, so that each rigid pipe segment adapts to the angle of the bending cavity where it is located.

[0011] In addition, under the wrapping of the outer layer, the catheter body composed of a plurality of rigid pipe segments has high overall strength, and the thrust efficiency is not greatly affected. Furthermore, under the connection of the elastic body, the activity resistance between the rigid pipe segments can be increased, so that the rigid pipe segments cannot move at will, so as to ensure that the catheter body has sufficient thrust efficiency, and the difficulty of movement of the rigid pipe segments of different catheter bodies can be adjusted according to actual needs.

[0012] The rigid pipe segment includes an intermediate rigid pipe segment and an end rigid pipe segment, and the end rigid pipe segment is arranged at both ends of the catheter body; The cross section of the intermediate rigid pipe segment is isosceles trapezoidal, and two oblique sides of the isosceles trapezoidal form two inclined surfaces of the intermediate rigid pipe segment; The cross section of the end rigid pipe segment is right trapezoidal, and the oblique side of the right trapezoidal forms an inclined surface of the end rigid pipe segment; Wherein, two adjacent inclined surfaces are connected to form a recess of the catheter body; The elastic body is in a ring structure or is surrounded by at least two independent elastic parts to form a hollow chamber outside the recess.

[0013] On one hand, the recess can increase the activity space and freedom between the rigid pipe segments, so as to adapt to smaller bending angles. On the other hand, the hollow chamber is formed under the closure of the elastic body, and when the catheter body is stressed due to the balloon or the bending of the blood vessel, the relative angular displacement occurs between the rigid pipe segments. At this time, the closed hollow chamber can serve as a buffer space. The air in the chamber can provide a soft cushioning effect, absorb part of the impact force, and more evenly transfer the concentrated stress to the surrounding elastic body and adjacent rigid pipe segments, effectively preventing the wear or plastic creep (permanent deformation) caused by excessive stress concentration at the contact point of the rigid pipe segments.

[0014] The first improvement way is that the rigid pipe segments are provided in a split manner, a head of one end of the intermediate rigid pipe segment is provided with a recess, and a head of the other end is provided with a protrusion; and the end rigid pipe segment is adaptively selected to be provided with a recess or a protrusion according to the head of the intermediate rigid pipe segment on the side where the end rigid pipe segment is located. The protrusion is engaged with the recess. The elastic body includes a bent arm and a horn part provided at two ends of the bent arm, and a connecting head is provided at an end of the horn part, and the connecting head is in a hook structure. An upper base of a cross section of the end rigid pipe segment forms a horizontal plane of the end rigid pipe segment, and two annular hook grooves are formed on the horizontal plane of the intermediate rigid pipe segment and face each other and dovetails of the inclined surface of the intermediate rigid pipe segment. An annular hook groove is formed on the horizontal plane of the end rigid pipe segment and faces a dovetail of the inclined surface of the end rigid pipe segment. The hook structure is connected with the hook groove.

[0015] Preferably, the hardness value of the rigid pipe segment is 30D-45D.

[0016] The second improvement way is that the rigid pipe segments are integrally formed. An annular straight insertion groove is formed on the inclined surface. The elastic body includes a bent arm and a horn part provided at two ends of the bent arm, and a connecting head is provided at an end of the horn part, and the connecting head is in a raindrop structure, and the raindrop structure is connected with the straight insertion groove.

[0017] Preferably, the hardness value of the rigid pipe segment is 30D-40D.

[0018] By setting the hardness value of the integrally formed rigid pipe segment to 30D-40D (30D-45D in the first improvement way), a geometric weak area is formed at the connection of the inclined surface by pre-setting a deep recess, the elastic deformation potential of the low-hardness material is utilized, the deepest point is allowed to be bent at a large angle, and finally the integrally formed rigid pipe segment is flexibly movable at the deepest recess without additional mechanical joints.

[0019] Further, the design of the outward-opening elbow arm and the inward-opening horn part releases sufficient deformation space for the concave area, and the low-hardness material is flexibly bent under the support of the arch arm; at the same time, the inward layout of the horn part converts the pulling force into bending stress directed to the root of the connecting head, so that the elastomer is easy to bend but not easy to break.

[0020] The second object of the present application is to provide a method for manufacturing the hollow microcatheter, and the steps include: The rigid pipe segment is sleeved on the central body; The central body sleeved with the rigid pipe segment is connected in the axial direction, and the connection mode adopts a tapered plug-in cooperation UV glue curing; The TPU or silicone rubber is coated on the rigid pipe segment outside by using a coaxial extruder to form an outer layer.

[0021] Compared with the prior art, the present application has the following beneficial effects: 1. In the hollow microcatheter and the preparation method thereof, the hardness value of the rigid pipe segment is between the hardness of the inner layer of the medical catheter and the hardness of the intermediate layer of the medical catheter, so that the rigid pipe segment itself has the ability to resist flattening and twisting, so that the microcatheter does not need to be provided with a metal / non-metal wire weaving / spiral layer, thereby solving the problem of reduced bending performance of the entire microcatheter caused by the intermediate layer.

[0022] 2. In the hollow microcatheter and the preparation method thereof, each rigid pipe segment can independently move, so that the rigid pipe segment can move according to the shape of the inner wall of the balloon, thereby adapting to the bending performance of the balloon, reaching the bending angle suitable for the balloon, and the balloon will not be lifted, and each rigid pipe segment is independently movable, so it will not affect other rigid pipe segments, so each rigid pipe segment adapts to the angle of the bending cavity where it is located, thereby solving the problem of insufficient adaptability of the microcatheter.

[0023] 3. In the hollow microcatheter and the preparation method thereof, the elastomer not only increases the movement resistance between the rigid pipe segments, so that the rigid pipe segments cannot move at will, to ensure that the catheter body has sufficient thrust efficiency, but also seals the outside of the concave part to form a hollow chamber, thereby serving as a buffer space to solve the problem of excessive concentration of the contact points of the rigid pipe segments and plastic creep. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a schematic diagram of the catheter body structure of the present application; Figure 2 It is an exploded view of the structure of part of the catheter body of the present application; Figure 3 It is an exploded view of the structure of the rigid pipe segment and the elastomer of the first embodiment of the present application; Figure 4 Structure diagram of intermediate rigid pipe segment of the first embodiment of the present application; Figure 5 Structure diagram of two connected intermediate rigid pipe segments of the first embodiment of the present application; Figure 6 Structure diagram of end rigid pipe segment of the first embodiment of the present application; Figure 7 Structure diagram of end rigid pipe segment and intermediate rigid pipe segment connection of the first embodiment of the present application; Figure 8 Structure diagram of independent elastic part of the fourth embodiment of the present application; Figure 9 Structure diagram of elastic body with hook-shaped end of the first embodiment of the present application; Figure 10 Structure diagram of elastic body with raindrop-shaped end of the second embodiment of the present application; Figure 11 Structure diagram of one of the application scenarios of the present application; Figure 12 Structure diagram of another of the application scenarios of the present application; Figure 13 Structure diagram of another of the application scenarios of the present application; Figure 14 Structure diagram of inner layer of the third embodiment of the present application; Figure 15 Exploded view of part of the microcatheter of the present application.

[0025] Meaning of each number in the figure is as follows: 1, outer layer; 2, elastic body; 21, bent arm; 22, connecting head; 23, horn part; 24, independent elastic part; 3, inner layer; 4, rigid pipe segment; 41, inclined surface; 42, horizontal surface; 43, connecting groove; 44, inner surface; 45, recess; 5, center body. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] When entering some twisted bifurcated lesions, side vessels or dealing with acute angle paths that may be faced when treating chronic total occlusion lesions, the catheter is affected by the intermediate layer (metal wire), resulting in that the bending performance of the catheter cannot be adapted to the balloon.

[0028] Figure 1 The catheter body capable of adapting to the balloon bending performance is shown, Figure 2 Part of the catheter body is shown by explosion, the catheter body is composed of multiple rigid pipe segments 4, the adjacent two rigid pipe segments 4 are movable, and there is a certain movable angle, which not only ensures the rigidity of the catheter body, but also improves the bending performance of the catheter body. Moreover, the adjacent two rigid pipe segments 4 are connected by setting the elastic body 2 to limit the maximum angle at which the rigid pipe segment 4 can move, the greater the limiting ability, the smaller the movable angle, the lower the bending performance of the catheter body, and the higher the thrust efficiency, so that the thrust is transmitted more smoothly between the two rigid pipe segments 4.

[0029] Further, the outer layer 1 is arranged outside the catheter body, and medical TPU or silicone rubber with high limit elasticity and fatigue resistance can be selected as the outer layer 1 wrapping the catheter body. The arrangement of the outer layer 1 forms a continuous circular arc surface on the outer surface of the catheter body and seals the outside of the catheter body, reducing friction. Moreover, under the wrapping of the outer layer 1, the overall integrity of the catheter body composed of multiple rigid pipe segments 4 is stronger, and the thrust efficiency is higher.

[0030] Further, the inner surface 44 of the rigid pipe segment 4 Figure 4 is shown in the figure) constitutes an inner layer 3, and the inner layer 3 is smooth, facilitating the smooth passage of a guide wire or other instruments through the inner cavity of the rigid pipe segment 4.

[0031] The first embodiment is shown in FIG. Figures 3-5 The rigid pipe segment 4 in the embodiment is arranged in a split manner, and the adjacent two rigid pipe segments 4 are connected by the elastic body 2. Figure 4 One of the rigid pipe segments 4 is shown, which is horizontally placed, forming a horizontal plane 42 on the outer side of the rigid pipe segment 4, and a slope 41 or two slopes 41.

[0032] Specifically, the rigid pipe segment 4 is divided into a middle rigid pipe segment and an end rigid pipe segment.

[0033] Figure 4 The middle rigid pipe segment shown has two slopes 41, and the cross section A of the middle rigid pipe segment is isosceles trapezoidal, with the upper base corresponding to the horizontal plane 42, the lower base corresponding to the inner surface 44, and the two slopes corresponding to the two slopes 41 of the middle rigid pipe segment. The middle rigid pipe segment mainly increases the length of the catheter body by itself, Figure 5 Two connected middle rigid pipe segments are shown, and after the two middle rigid pipe segments are connected, a recess 45 of the catheter body is formed between the two connecting slopes 41, making the two middle rigid pipe segments more easily movable. Moreover, one middle rigid pipe segment can be connected to one side or both sides of the two middle rigid pipe segments, and so on until the desired length is reached.

[0034] Figure 6 The end rigid pipe section shown has a slope 41, and the cross section A of the end rigid pipe section is a right trapezoid, with the upper base corresponding to the horizontal surface 42, the lower base corresponding to the inner surface 44, and a slope corresponding to the slope 41 of the end rigid pipe section. The end rigid pipe section is arranged at the two ends of the pipe body to avoid the existence of the extra slope 41 at the two ends of the pipe body. Figure 7 The end rigid pipe section is shown connected with the intermediate rigid pipe section. After the end rigid pipe section and the intermediate rigid pipe section are connected, the only slope 41 of the end rigid pipe section is connected with one of the slopes 41 of the intermediate rigid pipe section to form a recess 45 of the pipe body. The existence of the recess 45 makes the intermediate rigid pipe section and the end rigid pipe section more easily movable. Generally, the intermediate rigid pipe section has been connected with a sufficient number of intermediate rigid pipe sections on one side of the head end or tail end, and only the end rigid pipe section is connected on the other side of the head end or tail end intermediate rigid pipe section, so that each slope 41 on the pipe body can have a slope 41 adjacent thereto to form the recess 45, and there is no slope 41 that does not form the recess 45.

[0035] Referring to Figure 4 and Figure 6 The horizontal surface 42 of the intermediate rigid pipe section and the end rigid pipe section is provided with a connecting groove 43. The connecting groove 43 in the embodiment is a hook groove, which is dovetail-shaped, and the direction thereof is described by the dovetail. Specifically, referring to Figure 4 The horizontal surface 42 of the intermediate rigid pipe section is provided with two annular hook grooves around the surface thereof, which are opposite to each other and have dovetails opposite to the slope 41. Figure 6 The horizontal surface 42 of the end rigid pipe section is provided with one annular hook groove around the surface thereof, which has a dovetail opposite to the slope 41. The hook groove is connected with Figure 9 The elastic body 2 shown has two hook-shaped ends, and is annular. Therefore, when the annular elastic body 2 is connected with the hook groove, the outside of the recess 45 is closed to form a hollow chamber, thereby providing a movable space for the intermediate rigid pipe section or the end rigid pipe section. The elastic body 2 includes a bent arm 21, and the two ends of the bent arm 21 are provided with horn portions 23. The connecting head 22 is connected with the end of the horn portion 23. The connecting head 22 in the embodiment is hook-shaped, and is connected with the hook groove. After the connection, the bent arm 21 generates a pulling force to connect two intermediate rigid pipe sections or one intermediate rigid pipe section and one end rigid pipe section.

[0036] Due to the connection characteristics of the hook groove and the hook-shaped structure, the bent arm 21 needs to be unfolded to a certain angle in advance (i.e., the opening angle of the bent arm 21 is increased) to enable the hook-shaped structure to enter the hook groove and be engaged with the hook groove. After the engagement, the bent arm 21 restores the initial elastic force to a pulling force, so that the heads of two intermediate rigid pipe sections or one intermediate rigid pipe section and one end rigid pipe section are butted.

[0037] As preferred, the head of one end of the intermediate rigid pipe section is provided with a groove, and the head of the other end is provided with a protrusion, and the intermediate rigid pipe section is connected by the engagement of the protrusion and the groove. The end rigid pipe section is adaptively selected to be provided with a groove or a protrusion according to the head of the intermediate rigid pipe section on the side where the end rigid pipe section is located. Assuming that the head of the intermediate rigid pipe section to be connected is a groove, the end rigid pipe section provided with a protrusion is selected to be connected with the intermediate rigid pipe section. In other words, assuming that the head of the intermediate rigid pipe section to be connected is a protrusion, the end rigid pipe section provided with a groove is selected to be connected with the intermediate rigid pipe section.

[0038] The head connection mode of the two intermediate rigid pipe sections or the intermediate rigid pipe section and the end rigid pipe section is not limited to the engagement of the protrusion and the groove, and can also be the plug-in cooperation of the plate and the groove.

[0039] Further, although the catheter body is composed of the rigid pipe sections 4, the rigid pipe sections 4 are soft, not as hard as the steel structure or the iron structure, and can be deformed by hand, that is, the deformation can be observed or felt by eyes. Specifically, the hardness of the rigid pipe sections 4 is between the hardness of the inner layer of the medical catheter (the first hardness value) and the hardness of the intermediate layer (the second hardness value), and is closer to the hardness of the intermediate layer (the composite wire made of metal wire or non-metal wire). The hardness value (Shore D hardness) of the rigid pipe sections 4 is preferably in the range of 30D to 45D.

[0040] Comparison of the hardness of the medical catheter: The inner layer of the catheter (smooth lumen layer): usually very soft to ensure flexibility, and the hardness is <20D.

[0041] The intermediate layer (metal / non-metal wire weaving / spiral layer): provides core anti-flattening / anti-kinking strength, and the hardness depends on the base material; the hardness of the bearing wire alone is high (>50D), but the comprehensive hardness of the composite layer base (such as TPU coated with nylon / polyester fiber) is usually between 40D-60D.

[0042] In the embodiment, the hardness of the rigid pipe sections 4 is obviously higher than that of the inner layer of the medical catheter, so that the rigid pipe sections 4 are not easily deformed by flattening; and the hardness of the rigid pipe sections 4 is close to or slightly lower than that of the intermediate layer of the catheter with medium hardness, so that the rigid pipe sections 4 serve as the joint sections of the catheter body and move flexibly. The hardness of the rigid pipe sections 4 is selected to be in the range of 30D-45D, so that the rigid pipe sections 4 have sufficient rigidity to prevent flattening and can move flexibly when serving as the joint sections.

[0043] Different from the first embodiment, in the second embodiment, all the rigid pipe sections 4 are integrally formed.

[0044] In addition, the adjacent two rigid pipe sections 4 are connected by the elastic body 2.

[0045] Specifically, the rigid pipe segment 4 is divided into a middle rigid pipe segment and an end rigid pipe segment, the middle rigid pipe segment has two inclined surfaces 41, the cross section A of the middle rigid pipe segment is isosceles trapezoidal, the upper bottom corresponds to the horizontal surface 42, the lower bottom corresponds to the inner surface 44, and the two inclined sides correspond to the two inclined surfaces 41 of the middle rigid pipe segment. The end rigid pipe segment has one inclined surface 41, the cross section A of the end rigid pipe segment is right trapezoidal, the upper bottom corresponds to the horizontal surface 42, the lower bottom corresponds to the inner surface 44, and the one inclined side corresponds to the one inclined surface 41 of the end rigid pipe segment. The end rigid pipe segment is arranged at the two ends of the catheter body.

[0046] Among them, the two adjacent inclined surfaces 41 form the recess 45 of the catheter body.

[0047] Figure 10 The elastic body 2 with the end in the shape of a raindrop is shown, which includes a bent arm 21, a horn 23 is arranged at both ends of the bent arm 21, and a connecting head 22 is connected to the end of the horn 23. The connecting head 22 of the embodiment is in the shape of a raindrop. Referring to Figure 10 The inclined surface 41 of the middle rigid pipe segment and the end rigid pipe segment is provided with a ring-shaped connecting groove 43 around the surface thereof. The connecting groove 43 in the embodiment is a straight insertion groove, and the opening of the straight insertion groove is inclined upward to adapt to the insertion angle of the raindrop-shaped structure. The raindrop-shaped structure is connected with the straight insertion groove, and after the connection, the bent arm 21 generates a pushing force to support the two adjacent inclined surfaces 41.

[0048] In the embodiment, the elastic body 2 is annular, and therefore, the annular elastic body 2 can close the outside of the recess 45 to form a hollow chamber, thereby providing a moving space for the middle rigid pipe segment or the end rigid pipe segment.

[0049] The connection principle of the raindrop-shaped structure and the straight insertion groove is that the bent arm 21 is compressed by a certain angle (i.e. the opening angle of the bent arm 21 is reduced) in advance, so that the raindrop-shaped structure can enter the straight insertion groove and be connected with the straight insertion groove. After the connection, the bent arm 21 restores the initial elastic force and changes into a pushing force to support the two adjacent inclined surfaces 41.

[0050] It is further explained that the hardness value (Shore D hardness) of the rigid pipe segment 4 in the embodiment is preferably in the range of 30D to 40D, thereby ensuring that the rigid pipe segment 4 has sufficient rigidity to prevent crushing when serving as a joint segment, and also maintains necessary moderate softness to realize flexible and controllable bending movement. Specifically, the two adjacent rigid pipe segments 4 in the embodiment move through the connection part thereof, because the connection part is located at the deepest position of the recess 45, and therefore, the position is relatively weak, and in addition to the soft characteristics of the rigid pipe segment 4, the two adjacent rigid pipe segments 4 can realize flexible movement.

[0051] Figure 11An application scenario of the above two embodiments is shown, and the specific principle is as follows: when the catheter body enters the blood vessel, each rigid tube segment 4 is moved by itself to adapt to the bending angle of the blood vessel; then, the balloon is pushed into the blood vessel along the catheter body; at this time, because of the arrangement of the outer layer 1, the outer surfaces between the rigid tube segments 4 that adapt to the bending of the blood vessel can still maintain smooth transition, so that the balloon can be smoothly pushed into the lesion position in the blood vessel along the catheter body; then, the balloon is expanded, and at this time, the rigid tube segment 4 can still flexibly move according to the shape of the inner wall of the balloon, so as to adapt to the bending performance of the balloon, and reach the bending angle that is adapted to the balloon, and the balloon will not be lifted.

[0052] Figure 12 And Figure 13 Another application scenario of the above two embodiments is shown, and the specific principle is as follows: when facing an acute bending angle of 65°, the catheter body is moved by the plurality of rigid tube segments 4, and each rigid tube segment 4 only needs to be rotated by 1° in the bending direction on the basis of the previous rigid tube segment 4.

[0053] In fact, under the same bending distance and bending angle, the more the number of rigid tube segments 4, the smaller the angle of each rigid tube segment 4 in the bending direction on the basis of the previous rigid tube segment 4, and the smaller the length of each rigid tube segment 4, and the higher the machining precision.

[0054] On the basis of the above embodiments, the third embodiment adjusts the inner layer 3, and the catheter body is horizontally placed, the inner surface 44 of each rigid tube segment 4 is a complete circular arc surface, in this state, as shown in Figure 14 , the embodiment sets a coating layer on the inner surface 44 of the rigid tube segment 4 to form the inner layer 3, the coating layer adopts a hydrophilic polymer coating, including polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), etc., which expands to form a hydrogel layer after encountering water, so that the friction coefficient of the inner wall of the catheter is reduced from 0.3+ when dry to below 0.05, and the pushing resistance when the guide wire passes through is significantly reduced.

[0055] On the basis of the above embodiments, the fourth embodiment adjusts the elastic body 2, as shown in Figure 8 , the elastic body 2 of the embodiment is surrounded by at least two independent elastic parts 24 in a ring structure, and the embodiment preferably adopts twenty independent elastic parts 24 to surround the elastic body 2, so that the connecting head 22 of a single independent elastic part 24 is more easily connected with the hook slot or the straight insertion slot.

[0056] A preparation method is provided, and the purpose of the method is to manufacture the microcatheter in the first embodiment, as shown in Figure 15 , and the specific steps are as follows: Select a central body 5 with a target length, and the target length is 135cm-150cm; The end rigid pipe segment is sleeved into the head end of the center body 5 and is attached to the head end limiting sheet; The middle rigid pipe segment is sequentially sleeved into the center body 5; The other end rigid pipe segment is sleeved into the tail end of the center body 5, and the tail end limiting sheet is sleeved into the center body 5 to limit the middle rigid pipe segment and the end rigid pipe segment between the head end limiting sheet and the tail end limiting sheet; The elastic body 2 is sequentially installed in the connecting groove 43; The above steps prepare the center body 5 with the middle rigid pipe segment, the end rigid pipe segment and the elastic body 2 installed; The center body 5 with the middle rigid pipe segment, the end rigid pipe segment and the elastic body 2 installed is connected in the axial direction, and the connection mode is a tapered plug-in connection with medical-grade UV glue curing. Specifically, the head and tail of adjacent center bodies 5 are processed into tapered butt surfaces (length 0.5-1 mm), low-viscosity UV glue is applied, and curing is waited. Among them, the coaxial deviation is required to be ≤0.05 mm to prevent subsequent core deviation.

[0057] Continuous extrusion coating molding is adopted to coat the corresponding material outside the rigid pipe segment 4 to form the outer layer 1. The specific parameters are shown in the following table: Parameter TPU Silicone rubber Extrusion temperature 180~200℃ 120~140℃ Die diameter Outer diameter of catheter x 1.3 times Outer diameter of catheter x 1.5 times Pulling speed 0.8-1.2 m / min 0.5-0.8 m / min Vacuum sizing negative pressure -0.06 MPa -0.04 MPa The LaserScan sensor is used to detect the outer diameter of the assembly in real time, and then the extruder die position is adjusted (accuracy ±0.01 mm) to ensure that the elastic body 2 is filled outside without air bubbles; Finally, the microcatheter is cut according to the position of the butt joint of the center body 5.

[0058] In addition, a hydrophilic polymer coating can also be provided on the surface of the outer layer 1.

[0059] For the microcatheter in the second embodiment, the above steps can also be used, but only the integrally connected rigid pipe segment 4 needs to be directly sleeved outside the center body 5.

[0060] It should be noted that, as shown in Figure 14 Since the elastic body 2 in the second embodiment is accommodated in the recess 45, the microcatheter obtained by the second embodiment has a smaller radius than the microcatheter of the first embodiment under the condition that the rigid pipe segment 4 remains the same.

[0061] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A hollow microcatheter comprising a catheter body, an outer layer (1) disposed outside the catheter body, and an inner layer (3) disposed inside the catheter body, characterized in that: The catheter body at least comprises: Multiple rigid pipe sections (4), wherein the multiple rigid pipe sections (4) are closely arranged along an axis, and a movable angle is provided between two adjacent rigid pipe sections (4); An elastic body (2) disposed between two adjacent rigid pipe sections (4) is used to limit the size of the movable angle; a first hardness value and a second hardness value, the first hardness value being less than the second hardness value; The hardness value of the rigid pipe section (4) is between the first hardness value and the second hardness value.

2. The hollow microcatheter according to claim 1, characterized in that The first hardness value is less than 20D.

3. The hollow microcatheter according to claim 1, characterized in that The second hardness value is greater than 50D or 40D-60D.

4. The hollow microcatheter according to any one of claims 1 to 3, characterized in that: The rigid pipe section (4) is provided in a split manner or is integrally formed.

5. The hollow microcatheter according to any one of claims 1 to 3, characterized in that: The rigid pipe section (4) comprises a middle rigid pipe section and end rigid pipe sections, and the end rigid pipe sections are arranged at both ends of the catheter body; The cross section of the middle rigid pipe section is an isosceles trapezoid, and the two oblique sides of the isosceles trapezoid form two inclined surfaces (41) of the middle rigid pipe section; The cross section of the end rigid pipe section is a right-angled trapezoid, and the hypotenuse of the right-angled trapezoid forms the inclined surface (41) of the end rigid pipe section; Wherein, two adjacent inclined surfaces (41) are connected to form a concave (45) of the catheter body; The elastic body (2) is an annular structure or is formed by at least two independent elastic parts (24) to form an annular structure, so as to seal the outside of the recess (45) to form a hollow chamber.

6. The hollow microcatheter according to claim 5, characterized in that The rigid pipe section (4) is provided in a split manner, the head of one end of the middle rigid pipe section is provided with a groove, and the head of the other end is provided with a convex head; the end rigid pipe section is provided with a groove or a convex head according to the adaptability of the head of the middle rigid pipe section on its side; wherein the protrusion engages with the groove; The elastic body (2) comprises a curved arm (21) and horns (23) arranged at both ends of the curved arm (21); a connecting head (22) is provided at the end of the horn (23); and the connecting head (22) is a hook-shaped structure; The upper bottom of the cross section of the end rigid pipe section forms a horizontal surface (42) of the end rigid pipe section, and the horizontal surface (42) of the middle rigid pipe section is provided with two annular hook grooves facing in opposite directions and with their tails facing the inclined surface (41) of the middle rigid pipe section. A dovetail annular hook groove is provided on the horizontal surface (42) of the end rigid pipe section around the surface thereof, with the dovetail facing the inclined surface (41) of the end rigid pipe section; Wherein, the hook structure is connected to the hook groove.

7. The hollow microcatheter according to claim 6, characterized in that The hardness value of the rigid pipe section (4) is 30D-45D.

8. The hollow microcatheter according to claim 5, characterized in that The rigid pipe section (4) is integrally formed; The inclined surface (41) is provided with an annular straight slot around its surface; The elastic body (2) comprises a curved arm (21) and horns (23) arranged at both ends of the curved arm (21); a connector (22) is provided at the end of the horn (23); the connector (22) is a raindrop-shaped structure, and the raindrop-shaped structure is connected to the straight slot.

9. The hollow microcatheter according to claim 8, characterized in that The hardness value of the rigid pipe section (4) is 30D-40D.

10. A preparation method, characterized in that: The method for making the hollow microcatheter according to claim 1 comprises the following steps: Inserting the rigid pipe section (4) outside the central body (5); The central body (5) covered with the rigid pipe section (4) is connected axially, and the connection method adopts a conical plug-in method with UV glue curing; A coaxial extruder is used to coat TPU or silicone rubber on the outside of the rigid tube section (4) to form an outer layer (1).

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