Blocking calculus removal catheter and preparation method thereof

Abstract

The catheter comprises a hollow outer sheath tube, the tail end of the outer sheath tube is connected with the head end of a handle, the handle is provided with a handle through hole penetrating through the head end and the tail end of the handle, the handle through hole is communicated with the outer sheath tube, the head end of a pushing rod is located in the handle through hole, and the pushing rod freely slides in the handle through hole. The head end of the pushing rod is connected with the tail end of the core wire, the head end of the core wire is connected with the tail end of the memory alloy spring, the head end of the core wire and the memory alloy spring sequentially penetrate through a handle through hole and the outer sheath tube and are exposed out of the head end of the outer sheath tube, a check valve is arranged at the head end of the outer sheath tube and is in a disc shape, and the outer ring side of the check valve is fixed to the inner wall of the head end of the outer sheath tube. A center channel hole for the core wire and the memory alloy spring to pass through is formed in the center of the check valve, and the hole diameter of the center channel hole is matched with the wire diameter of the core wire and the wire diameter of the memory alloy spring. The invention further discloses a preparation method of the blocking calculus removal catheter. Due to the arrangement of the check valve, liquid leakage in the operation process can be effectively prevented.

Description

Technical Field

[0001] The invention belongs to the field of medical devices, and specifically relates to a blocking lithotripsy catheter, and also relates to a preparation method of the blocking lithotripsy catheter. The invention is suitable for blocking lithotripsy of stone fragments. Background Art

[0002] In urological surgery, in order to prevent stone fragments from continuing to penetrate into the human body, medical devices for blocking and removing stones are usually used to extend behind the stone to block the stone, and then remove the stone fragments after the stone is crushed. Among these instruments, the blocking stone removal catheter is the most commonly used one. There are some defects in the existing medical devices for blocking and removing stones on the market: for example, the blocking stone removal catheter produced by a company in Shanghai has a large gap between the blocking materials after folding. During use, the broken stones may move up through the gap of the blocker, causing secondary contamination of the urinary tract; the nickel-titanium alloy urinary system stone removal net (occluder) produced by a company in the United States: the product is a threaded structure that opens behind the stone. Since the opening size of the net basket is fixed, it may not be able to completely block the ureter when it is opened behind the stone. In addition, during use, due to the lack of effective blocking of the catheter head, the liquid refluxes along the catheter, resulting in contamination of cooperating instruments such as endoscopes, resulting in surgical failure. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the prior art, provide a plugging stone removal catheter, and also provide a preparation method of the plugging stone removal catheter. The above purpose of the present invention is achieved by the following technical means:

[0004] A plugging and stone removal catheter comprises a hollow outer sheath tube, the rear end of the outer sheath tube is connected to the front end of a handle, a handle through hole is provided on the handle which passes through the front and rear ends of the handle and is connected to the rear end of the outer sheath tube, the front end of a push rod is located in the handle through hole, the push rod slides freely in the handle through hole, the front end of the push rod is connected to the rear end of a core wire, the front end of the core wire is connected to the rear end of a memory alloy spring, the front end of the core wire and the memory alloy spring pass through the handle through hole and the outer sheath tube in sequence and are exposed from the front end of the outer sheath tube, a check valve is provided at the front end of the outer sheath tube, the outer ring side of the check valve is fixed to the inner wall of the front end of the outer sheath tube, a central channel hole for the core wire and the memory alloy spring to pass through is provided at the center of the check valve, and the aperture of the central channel hole is adapted to the wire diameter of the core wire and the memory alloy spring;

[0005] The check valve comprises a sealing ring and a buffer ring which are arranged concentrically, the inner side of the buffer ring is connected to the outer side of the sealing ring, the outer side of the buffer ring is fixed to the inner wall of the outer sheath tube, and the thickness of the buffer ring is smaller than that of the sealing ring;

[0006] The core wire diameter is the same as the memory alloy spring wire diameter;

[0007] After the memory alloy spring is completely extended out of the head end of the outer sheath tube, the head end diameter of the memory alloy spring is smaller than the tail end diameter;

[0008] When the push rod does not move toward the outer sheath tube in the initial state, the memory alloy spring is completely retracted in the outer sheath tube.

[0009] The core wire is provided with a hydrophilic coating, and the memory alloy spring is provided with a hydrophobic coating.

[0010] The hydrophilic coating is polyvinyl pyrrolidone (PVP), and the hydrophobic coating is polytetrafluoroethylene (PTFE);

[0011] A preparation method for blocking a stone removal catheter comprises the following steps:

[0012] Step 1, using medical grade polypropylene to prepare an outer sheath tube through a compression molding process;

[0013] Step 2, using nickel-titanium alloy to make a core wire through a drawing process;

[0014] Step 3, cutting the core wire obtained in step 2 into a spring shape by laser and immediately subjecting the spring to heat treatment to obtain a memory alloy spring;

[0015] Step 4: Use the medical grade plastics to make a handle and a push rod through an injection molding process;

[0016] Step 5, making the medical grade silicone into a check valve through an injection molding process;

[0017] Step 6: Apply a hydrophilic coating on the core wire and a hydrophobic coating on the memory alloy spring;

[0018] Step 7. Weld the outer side of the check valve to the inner wall of the outer sheath tube head end, insert the tail end of the core wire from the head end of the outer sheath tube, extend it through the check valve and out from the tail end of the outer sheath tube, ensure that the memory alloy spring on the core wire is located inside the outer sheath tube, fix the tail end of the outer sheath tube to the head end of the handle, fix the tail end of the core wire to the head end of the push rod, and place the push rod into the handle through hole of the handle, and finally wrap the anti-slip tape around the handle.

[0019] The hydrophilic coating comprises the following steps:

[0020] Step 1, using ethanol or isopropanol solvent to ultrasonically clean the core wire;

[0021] Step 2, polyvinyl pyrrolidone (PVP), N,N'-methylenebisacrylamide (BIS), and anhydrous ethanol are mixed and stirred in a volume ratio of 10:60:10 to obtain a PVP solution;

[0022] Step 3, using a dipping or spraying method to evenly coat the prepared PVP solution on the surface of the cleaned core wire;

[0023] Step 4, curing the coated core wire at 40°C to 90°C for 2 to 4 hours;

[0024] Step 5: Grind and polish the cured coating.

[0025] The application of the hydrophobic coating comprises the following steps:

[0026] Step 1: Use an organic solvent to clean the surface of the memory alloy spring, and use sandpaper or a wire brush to remove the dirt and oxide layer on the surface of the memory alloy spring;

[0027] Step 2, mixing PTFE resin, solvent and titanate coupling agent in a volume ratio of 100:80:30 and stirring to obtain a PTFE solution; the solvent is a mixed solvent of N,N-dimethylformamide and N-methyl-2-pyrrolidone in a volume ratio of 1:1;

[0028] Step 3, evenly coating the PTFE solution on the cleaned memory alloy spring by spraying;

[0029] Step 4, leaving the sprayed memory alloy spring to dry at room temperature, and then heat curing it in a high temperature drying oven at 270°C for 1 hour;

[0030] Step 5: Grind and polish the cured PEFE-coated memory alloy spring.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. Through the setting of the check valve, when the memory alloy spring passes through the check valve and eccentrically squeezes the check valve, the buffer ring will deform before the sealing ring, and the memory alloy spring drives the sealing ring to move eccentrically, ensuring that the memory alloy spring always seals through the sealing ring, so that the check valve has a better sealing effect and effectively prevents leakage during surgery.

[0033] 2. The core wire and the memory alloy spring are both provided with a low-friction coating, which reduces the damage to the patient's tissue and alleviates the patient's pain. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the memory alloy spring of the present invention when it is located outside the outer sheath tube;

[0035] Figure 2 It is a schematic structural diagram of the present invention when the memory alloy spring is located inside the outer sheath tube;

[0036] Figure 3 This is a schematic diagram of the first structure of the check valve;

[0037] Figure 4 A schematic diagram of the transverse cross-sectional structure of the second structure of the check valve;

[0038] Figure 5 A schematic diagram of the longitudinal section structure of the second structure of the check valve;

[0039] Among them: 1-core wire, 2-memory alloy spring, 3-check valve, 4-outer sheath, 5-handle, 6-sealing ring, 7-push rod, 8-buffer ring. DETAILED DESCRIPTION

[0040] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the implementation examples described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0041] Embodiment 1:

[0042] like Figures 1 to 5 As shown, a blocking and stone removal catheter comprises a hollow outer sheath tube 4, the tail end of the outer sheath tube 4 is connected to the head end of a handle 5, the handle 5 is provided with a handle through hole penetrating the head end and the tail end of the handle 5, and the handle through hole is connected to the tail end of the outer sheath tube 4, the head end of a push rod 7 is located in the handle through hole, the push rod 7 slides freely in the handle through hole, the head end of the push rod 7 is connected to the tail end of a core wire 1, the head end of the core wire 1 is connected to the tail end of a memory alloy spring 2, and the head end of the core wire 1 together with the memory alloy spring 2 can pass through the The handle through hole and the outer sheath tube 4 are exposed from the head end of the outer sheath tube 4. The head end of the outer sheath tube 4 is provided with a check valve 3, which is disc-shaped. The outer ring side of the check valve 3 is fixed to the inner wall of the head end of the outer sheath tube 4. The center of the check valve 3 is provided with a central channel hole for the core wire 1 and the memory alloy spring 2 to pass through. The aperture of the central channel hole is adapted to the wire diameter of the core wire 1 and the memory alloy spring 2. The material of the core wire 1 is nickel-titanium alloy, and the memory alloy spring 2 is obtained by laser cutting and heat treatment of nickel-titanium alloy. In this embodiment, the diameter of the core wire 1 is the same as the wire diameter of the memory alloy spring 2.

[0043] The material of the check valve 3 is medical grade silicone. The setting of the check valve 3 can effectively prevent the accumulated fluid from flowing into the outer sheath 4 during surgery, thereby avoiding leakage.

[0044] When the push rod 7 moves relative to the handle 5, the core wire 1 can be driven to move. In this embodiment, when the push rod 7 does not move toward the outer sheath tube 4 in the initial state, the memory alloy spring 2 is completely retracted in the outer sheath tube 4. When the memory alloy spring 2 is completely extended out of the head end of the outer sheath tube 4, the memory alloy spring 2 returns to a spring shape, and the memory alloy spring 2 constitutes a blocking body.

[0045] In some embodiments, after the memory alloy spring 2 is completely extended out of the head end of the outer sheath tube 4, the memory alloy spring 2 returns to a spring shape, and the head end diameter of the memory alloy spring 2 is smaller than the tail end diameter.

[0046] As a preferred solution, the check valve 3 includes a concentrically arranged sealing ring 6 and a buffer ring 8, the inner ring of the buffer ring 8 is connected to the outer ring of the sealing ring 6, the inner ring diameter of the sealing ring 6 is adapted to the core wire 1 diameter and the wire diameter of the memory alloy spring 2 (or the inner ring diameter of the sealing ring 6 is smaller than the core wire 1 diameter and the wire diameter of the memory alloy spring 2), the outer ring of the buffer ring 8 is fixed to the inner wall of the head end of the outer sheath 4, and the thickness of the buffer ring 8 is smaller than the thickness of the sealing ring 6. The existing check valve 3 only has a perforation on the disc-shaped valve body. When the memory alloy spring 2 passes through the check valve 3, the memory alloy spring 2 is bent, and the memory alloy spring 2 will squeeze the check valve 3. When the squeezing force is too large, the perforation is deformed, and a gap is generated between the memory alloy spring 2 and the check valve 3, affecting the sealing effect of the check valve 3.

[0047] In some embodiments, the thickness of the buffer ring 8 is less than that of the sealing ring 6. The buffer ring 8 is more likely to deform when subjected to force than the sealing ring 6. When the memory alloy spring 2 passes through the check valve 3 and eccentrically squeezes the check valve 3, the buffer ring 8 will deform before the sealing ring 6. The memory alloy spring 2 drives the sealing ring 6 to move eccentrically, ensuring that the memory alloy spring 2 always seals through the sealing ring 6, so that the check valve 3 has a better sealing effect.

[0048] The handle 5 is provided with an anti-skid belt to improve the stability and comfort of operation. In some embodiments, the anti-skid belt is made of silicone material.

[0049] In some embodiments, the core wire 1 is provided with a low-friction coating, which reduces the friction resistance of the core wire 1 when it moves in a human blood vessel or cavity, thereby improving its pushability and maneuverability. The low-friction coating is usually provided on the outer surface of the core wire 1 to reduce the friction when it moves in a human blood vessel or cavity.

[0050] The material of the low friction coating can be a hydrophilic coating or a hydrophobic coating. The hydrophilic coating material usually includes polyvinyl pyrrolidone (PVP) and the like, and the hydrophobic coating material usually includes polytetrafluoroethylene (PTFE) which can also reduce friction. Usually, one or two or more coating materials are used to apply different coatings to different parts of the plugging and stone removal catheter. In this embodiment, a hydrophilic coating - polyvinyl pyrrolidone (PVP) is used on the core wire 1.

[0051] The memory alloy spring 2 is conventionally not coated with a low friction coating. However, in order to improve the recovery and resilience of the memory alloy spring 2, in this embodiment, a polytetrafluoroethylene (PTFE) coating is coated on the surface of the memory alloy spring 2 to reduce friction, and at the same time, the memory alloy spring 2 also has good biocompatibility.

[0052] Embodiment 2:

[0053] The present invention also provides a method for preparing the stone removal catheter of the above-mentioned embodiment 1, comprising the following steps:

[0054] Step 1: Preparation of the outer sheath tube 4 . Medical grade polypropylene is selected and the outer sheath tube 4 is prepared by a compression molding process to ensure that its inner diameter is suitable for the movement of the core wire 1 .

[0055] Material: Medical grade polypropylene (brand: PP-RCT) is selected.

[0056] Equipment: Injection molding machine (model: ENGELVictory).

[0057] Process parameters:

[0058] Barrel temperature: 220-250℃.

[0059] Mould temperature: 50-80℃.

[0060] Injection pressure: 80-140MPa.

[0061] Holding pressure: 30-60MPa.

[0062] Injection speed: medium, about 1.1m / s.

[0063] Cooldown time: 20-30 seconds.

[0064] The dimensions of the prepared outer sheath tube are: outer diameter (2-3) mm, inner diameter (1.6-2.4) mm, and length (260-340) mm.

[0065] Step 2: Preparation of the core wire 1 . A suitable metal material, such as copper-zinc alloy, nickel-titanium alloy or iron-platinum alloy, is selected and made into the core wire 1 by a drawing process, the outer diameter of which is smaller than the inner diameter of the outer sheath tube 4 .

[0066] Material: This embodiment selects a typical representative: nickel-titanium alloy (brand: Nitinol).

[0067] Equipment: Drawing machine.

[0068] Process parameters:

[0069] Drawing temperature: 600-800℃.

[0070] Drawing speed: 10-20m / min.

[0071] Annealing temperature: 450-500℃.

[0072] Annealing time: 30-60 minutes.

[0073] The specifications of the prepared core wire are: outer diameter (0.8-1.2) mm, length (290-370) mm (slightly longer than the outer sheath).

[0074] Step 3: Preparation of the memory alloy spring 2. The core wire 1 obtained in step 2 is selected and made into the memory alloy spring 2 through laser cutting and heat treatment processes to ensure that it has shape memory properties at human body temperature. Laser cutting can ensure the shape and size of the memory alloy spring 2. Heat treatment is performed immediately after laser cutting to reduce the adverse effects of the heat-affected zone and optimize the shape memory properties of the memory alloy spring 2.

[0075] Material: Nickel-titanium alloy (grade: Nitinol).

[0076] Equipment: Laser cutting machine (model: TRUMPF).

[0077] Process parameters:

[0078] Laser power: 100W.

[0079] Cutting speed: 5mm / s.

[0080] Heat treatment temperature: 500℃.

[0081] Heat treatment time: 60 minutes.

[0082] Specifications of memory alloy spring 2: outer diameter (0.8~1.2) mm, length (45~55) mm.

[0083] Step 4: Preparation of handle 5 and push rod 7. Medical grade plastic material is selected and the handle 5 and push rod 7 are made by injection molding process to ensure that the structure is stable and easy to operate.

[0084] Material: Medical grade plastic, namely polyetheretherketone (grade: PEEK).

[0085] Equipment: Injection molding machine (model: ENGEL Victory).

[0086] Process parameters:

[0087] Barrel temperature: 220-250℃.

[0088] Mould temperature: 50-80℃.

[0089] Injection pressure: 80-140MPa.

[0090] Holding pressure: 30-60MPa.

[0091] Injection speed: medium speed.

[0092] Cooldown time: 20-30 seconds.

[0093] Specifications of the handle 5 and the push rod 7: handle length (80-120) mm, push rod diameter (1.3-1.7) mm, length (110-130) mm.

[0094] Step 5: Preparation of the check valve 3. Choose medical grade silicone as the material, which has excellent biocompatibility and flexibility. Choose LSR (liquid silicone) series.

[0095] Equipment: A high-precision injection molding machine is used to perform silicone injection molding to obtain the check valve 3. The injection molding machine model is the WITTMANN Group series.

[0096] Processing parameters: Injection molding temperature: generally 150-200℃.

[0097] The sizes of the check valve 3 and the outer sheath 4 are compatible, the check valve 3 is nested inside the outer sheath 4, the outer diameter of the check valve 3 is adapted to the inner diameter of the outer sheath 4, and the diameter of the central channel hole of the check valve 3 is adapted to the diameter of the core wire. The outer diameter of the check valve is connected and fixed to the head end of the outer sheath.

[0098] Step 6: The core wire 1 and the memory alloy spring 2 are coated with a low friction coating;

[0099] The coating process of polytetrafluoroethylene PTFE is as follows:

[0100] 1. Pretreatment: Use organic solvents such as acetone or ethanol to clean the substrate (memory alloy spring), and then use sandpaper or wire brush to remove the dirt and oxide layer on the surface to ensure the adhesion between the coating and the substrate.

[0101] 2. Preparation of coating solution: According to the specific application requirements and coating performance requirements, polytetrafluoroethylene PTFE (3M TM Dyneon TM PTFE TF 5070GZ) is mixed with a solvent (a mixed solvent of N,N-dimethylformamide and N-methyl-2-pyrrolidone, with a volume ratio of 1:1) and an auxiliary agent (titanate coupling agent NDZ-311W) in a ratio of 100:80:30 by volume to obtain a PTFE coating solution.

[0102] 3. Coating: The PTFE coating solution is evenly coated on the pretreated substrate surface by spraying.

[0103] 4. Drying and curing: Leave the sprayed substrate to dry at room temperature first, then heat cure it in a high-temperature drying oven at 270°C for 1 hour.

[0104] 5. Post-processing: The cured coated substrate undergoes some post-processing steps, such as grinding, polishing, spraying primer, etc., to further improve the appearance and performance of the coating.

[0105] The coating process of polyvinyl pyrrolidone (PVP) is as follows:

[0106] 1. Surface pretreatment: Clean the surface of the substrate (core wire) to remove grease and impurities. You can use ethanol, isopropanol and other solvents for ultrasonic cleaning.

[0107] 2. Preparation of coating solution:

[0108] Selection of polyvinyl pyrrolidone (PVP): PVP K30 (molecular weight about 400,000) is usually used

[0109] Solvent: Commonly used solvents include ethanol, isopropanol, etc. Selecting the appropriate concentration can better control the adhesion and smoothness of the prepared coating.

[0110] Crosslinking agent: N,N'-methylenebisacrylamide (BIS)

[0111] Formula: Polyvinylpyrrolidone (PVP), cross-linking agent, and anhydrous ethanol are mixed in a volume ratio of 10:60:10 to form a uniform solution at room temperature. The specific formula ratio may need to be adjusted according to actual application and performance requirements to obtain a PVP solution.

[0112] 3. Coating: The prepared PVP solution is evenly coated on the pre-treated substrate surface. The coating is carried out by dipping, spraying and other methods.

[0113] 4. Curing: Curing the coated substrate at 40°C to 90°C for 2 to 4 hours to form a stable coating.

[0114] 5. Post-treatment: The substrate with the cured coating is post-treated, such as grinding and polishing, to improve the surface quality and performance of the coating.

[0115] Step 7: Assembly of components.

[0116] 1. The check valve 3 is welded and installed; the outer ring of the check valve 3 is connected to the inner wall of the first end of the outer sheath tube 4 by a fusion welding process.

[0117] The fusion welding equipment uses a high frequency welding machine or an ultrasonic welding machine.

[0118] Melting welding temperature: usually slightly higher than the melting point of silicone material, about 180 ~ 220 ℃.

[0119] Pressure: 150MPa~190MPa, ensure sufficient pressure to make the check valve and the outer sheath tube tightly connected.

[0120] 2. Assembling the outer sheath tube 4 and the core wire 1;

[0121] Insert the tail end of the core wire 1 from the head end of the outer sheath tube 4 , extend it into the check valve 3 and pass through the tail end of the outer sheath tube 4 , and ensure that the memory alloy spring 2 is inside the outer sheath tube 4 .

[0122] 3. Installation of handle 5 and push rod 7;

[0123] The tail end of the outer sheath tube 4 is fixed to the head end of the handle 5 by gluing; then the tail end of the core wire 1 is fixedly connected to the head end of the push rod 7, and the push rod 7 is placed into the handle through hole of the handle 5.

[0124] 4. Installation of anti-slip belt:

[0125] An anti-slip tape is wound around the handle 5 to improve the stability and comfort of operation.

[0126] During the operation, the doctor first inserts the outer sheath tube 4 into the patient's body, controls the movement of the core wire 1 through the push rod 7, and makes the memory alloy spring 2 extend out of the head end of the outer sheath tube 4 and form an occlusion body at the target position. After the stone is crushed, the doctor controls the handle 5 and the push rod 7 at the same time to remove the stone.

[0127] To illustrate the effectiveness of the present invention, the present invention and the traditional catheter were selected as research comparison objects in the clinical trial. The following are some key clinical trial results and comparison data: The target number of the experiment is 20 people.

[0128] 1. Operation time

[0129] The present invention: The average operation time was (35.2±9.5) minutes.

[0130] Traditional catheter: The average operation time was (54.7±14.4) minutes.

[0131] 2. One-time stone clearance rate

[0132] The present invention: the one-time stone removal rate is 95.4%.

[0133] Traditional catheter: One-time stone-free rate was 79.6%.

[0134] 3. Postoperative bleeding

[0135] The present invention: The average blood loss after surgery was (23±6.7) ml.

[0136] Traditional catheter: The average postoperative blood loss was (25±7.1) ml.

[0137] 4. Postoperative fever

[0138] The present invention: The incidence of postoperative fever was 4 cases.

[0139] Traditional catheter: Postoperative fever occurred in 6 cases.

[0140] 5. Length of hospital stay

[0141] The present invention: The average hospital stay is 4.5 days.

[0142] Traditional catheters: Average length of stay was 8.6 days.

[0143] 6. Surgical success rate

[0144] The present invention: The operation success rate is 97.3%.

[0145] Traditional catheter: The procedural success rate was 68.5%.

[0146] Based on the above data, the present invention has shown significant superiority in clinical trials. Compared with traditional catheters, the new catheter can significantly improve surgical efficiency, reduce patient pain, and has higher clinical application value and promotion prospects.

[0147] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.

[0148] It should be noted that the embodiments described in the present invention are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the described embodiments or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

Claims

1. A plugging and stone removal catheter, comprising a hollow outer sheath tube (4), characterized in that: The rear end of the outer sheath tube (4) is connected to the front end of the handle (5), the handle (5) is provided with a handle through hole penetrating the front and rear ends of the handle (5), and the handle through hole is connected to the rear end of the outer sheath tube (4), the front end of the push rod (7) is located in the handle through hole, the push rod (7) slides freely in the handle through hole, the front end of the push rod (7) is connected to the rear end of the core wire (1), the front end of the core wire (1) is connected to the rear end of the memory alloy spring (2), and the front end of the core wire (1) is connected to the rear end of the memory alloy spring (2). The memory alloy spring (2) passes through the handle through hole and the outer sheath tube (4) in sequence and emerges from the head end of the outer sheath tube (4). The head end of the outer sheath tube (4) is provided with a check valve (3). The outer ring side of the check valve (3) is fixed to the inner wall of the head end of the outer sheath tube (4). The center of the check valve (3) is provided with a central channel hole for the core wire (1) and the memory alloy spring (2) to pass through. The aperture of the central channel hole is adapted to the wire diameter of the core wire (1) and the memory alloy spring (2).

2. The stone removal catheter blocking device according to claim 1, characterized in that: The check valve (3) comprises a sealing ring (6) and a buffer ring (8) which are arranged concentrically, the inner side of the buffer ring (8) is connected to the outer side of the sealing ring (6), the outer side of the buffer ring (8) is fixed to the inner wall of the outer sheath tube (4), and the thickness of the buffer ring (8) is smaller than the thickness of the sealing ring (6).

3. The stone removal catheter blocking device according to claim 1, characterized in that: The diameter of the core wire (1) is the same as the wire diameter of the memory alloy spring (2).

4. The stone removal catheter blocking device according to claim 1, characterized in that: After the memory alloy spring (2) is completely extended out of the head end of the outer sheath tube (4), the head end diameter of the memory alloy spring (2) is smaller than the tail end diameter.

5. The stone removal catheter blocking device according to claim 4, characterized in that: When the pushing rod (7) does not move toward the outer sheath tube (4) in the initial state, the memory alloy spring (2) is completely retracted into the outer sheath tube (4).

6. The stone removal catheter blocking device according to claim 5, characterized in that: The core wire (1) is provided with a hydrophilic coating, and the memory alloy spring (2) is provided with a hydrophobic coating.

7. The stone removal catheter blocking device according to claim 6, characterized in that: The hydrophilic coating is polyvinyl pyrrolidone (PVP), and the hydrophobic coating is polytetrafluoroethylene (PTFE).

8. A method for preparing a stone removal catheter for blocking according to claim 7, characterized in that: The following steps are involved: Step 1, selecting medical grade polypropylene to prepare an outer sheath tube (4) through a compression molding process; Step 2, selecting a nickel-titanium alloy and forming a core wire (1) through a drawing process; Step 3, cutting the core wire (1) obtained in step 2 into a spring shape by laser and immediately heat treating the spring to obtain a memory alloy spring (2); Step 4: Using medical grade plastics through injection molding to form a handle (5) and a push rod (7); Step 5, forming a check valve (3) by injection molding the medical grade silicone; Step 6: applying a hydrophilic coating on the core wire (1) and applying a hydrophobic coating on the memory alloy spring (2); Step 7, weld the outer side of the check valve (3) to the inner wall of the head end of the outer sheath tube (4), insert the tail end of the core wire (1) from the head end of the outer sheath tube (4), extend it through the check valve (3) and pass it out from the tail end of the outer sheath tube (4), ensure that the memory alloy spring (2) on the core wire (1) is located inside the outer sheath tube (4), fix the tail end of the outer sheath tube (4) to the head end of the handle (5), fix the tail end of the core wire (1) to the head end of the push rod (7), and put the push rod (7) into the handle through hole of the handle (5), and finally wrap the anti-slip tape around the handle (5).

9. The method for preparing a stone removal catheter for blocking according to claim 8, characterized in that: The hydrophilic coating comprises the following steps: Step 1, using ethanol or isopropanol solvent to ultrasonically clean the core wire (1); Step 2, polyvinyl pyrrolidone (PVP), N,N'-methylenebisacrylamide (BIS), and anhydrous ethanol are mixed and stirred in a volume ratio of 10:60:10 to obtain a uniform solution, thereby obtaining a PVP solution; Step 3, using a dipping or spraying method to evenly coat the prepared PVP solution on the surface of the cleaned core wire (1); Step 4, curing the coated core wire (1) at a temperature between 40° C. and 90° C. for 2 to 4 hours; Step 5: grinding and polishing the cured coated core wire (1).

10. The method for preparing a stone removal catheter for blocking according to claim 8, characterized in that: The application of the hydrophobic coating comprises the following steps: Step 1: Clean the surface of the memory alloy spring (2) with an organic solvent, and remove dirt and an oxide layer on the surface of the memory alloy spring (2) with sandpaper or a wire brush; Step 2, mixing PTFE resin, solvent and titanate coupling agent in a volume ratio of 100:80:30 and stirring to obtain a PTFE solution; the solvent is a mixed solvent of N,N-dimethylformamide and N-methyl-2-pyrrolidone in a volume ratio of 1:1; Step 3, evenly coating the PTFE solution on the cleaned memory alloy spring (2) by spraying; Step 4, leaving the sprayed memory alloy spring (2) to dry at room temperature, and then heat curing it in a high temperature drying oven at 270° C. for 1 hour; Step 5: Grinding and polishing the memory alloy spring (2) with the cured PEFE coating.

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