A fibrin sheath clearing device

Abstract

This invention relates to the field of dialysis technology and provides a fibrin sheath removal device, comprising: a tubing body including a proximal hard segment, a distal cutting segment, and a cutting head at the end of the cutting segment, the cutting head having a sharp blade; a quick exchange port provided on the side wall of the tubing body; and a fixing member disposed within the tubing body, the distal end of the fixing member extending from the quick exchange port for fixing a central venous catheter located within the cutting segment, the proximal end of the fixing member extending through the proximal end of the tubing body. In use, the fibrin sheath removal device of this invention involves placing the cutting segment over the central venous catheter to be removed, with the proximal end of the central venous catheter exposed at the quick exchange port and fixed by the fixing member to prevent displacement of the central venous catheter during removal. The fibrin sheath outside the central venous catheter is then peeled off using the cutting head.

Description

Technical Field

[0001] This invention relates to the field of dialysis technology, and more specifically to a fibrin sheath removal device. Background Technology

[0002] With the rapid advancements in dialysis technology, patients are surviving longer, highlighting the increasing importance of hemodialysis access. Long-term hemodialysis access methods primarily include arteriovenous fistulas (AVFs), artificial blood vessel fistulas (AVFs), and central venous catheters (CVCs). CVCs are an important type of access; however, as the catheter remains in place for extended periods, a fibrin sheath develops around it. This fibrin sheath, averaging 1-2 mm thick, consists of an inner cellular / inflammatory layer composed of lymphocytes, plasma cells, neutrophils, macrophages, multinucleated giant cells, and spindle cells, and an outer layer of collagen and fibroblasts. Studies have found no gaps between the fibrin sheath and the catheter, making it prone to catheter failure and preventing patients from undergoing normal hemodialysis treatment. Summary of the Invention

[0003] Therefore, the present invention aims to solve the problem that fibrin sheaths appear around central venous catheters in the prior art, which can easily cause catheter failure and prevent patients from undergoing normal hemodialysis treatment, and thus provides a fibrin sheath removal device.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: This invention provides a fibrin sheath removal device, comprising: a tube body including a proximal hard segment, a distal cutting segment, and a cutting head at the end of the cutting segment, the cutting head having a sharp blade; a quick exchange port provided on the side wall of the tube body; and a fixing member disposed within the tube body, the distal end of the fixing member extending from the quick exchange port for fixing a central venous catheter located within the cutting segment, the proximal end of the fixing member extending through the proximal end of the tube body.

[0005] Furthermore, the fibrin sheath removal device also includes a handle with a rotating component on it. The proximal end of the tube is connected to the rotating component, and the tube can be rotated by rotating the rotating component. The proximal end of the fixing component is fixed to the handle.

[0006] Furthermore, the cutting head has a flat, serrated, or pointed blade shape.

[0007] Furthermore, the inner wall of the cutting head is provided with protrusions, and the distance between the blade and the central venous catheter can be controlled by changing the height of the protrusions.

[0008] Furthermore, the tube body of the cut section has a hollow structure formed by cutting.

[0009] Furthermore, the quick-swap port is located at the intersection of the hard segment and the cutting segment.

[0010] Furthermore, the fibrin sheath removal device also includes a distal protection device adapted to be positioned distal to the central venous catheter to collect the fibrin sheath removed by the cutting head.

[0011] Furthermore, the remote protection device is a radially retractable and self-expanding conical structure.

[0012] Furthermore, the remote protection device is initially confined by the sleeve in a retracted state, and automatically opens into an expanded state after being released from the sleeve.

[0013] Furthermore, the remote protection device includes a frame and a polymer membrane disposed on the frame, the polymer membrane having micropores.

[0014] The technical solution of this invention has the following advantages: The fibrin sheath removal device provided by the present invention involves placing a cutting segment over the outside of the central venous catheter whose fibrin sheath is to be removed. The proximal end of the central venous catheter is exposed at the quick exchange port and fixed by a fixator to prevent the central venous catheter from moving during the removal process. Then, the cutting head is used to peel off the fibrin sheath outside the central venous catheter. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the fibrin sheath removal device in an embodiment of the present invention; Figure 2 This is a schematic diagram of the tube body in the fibrin sheath removal device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the cutting head in a fibrin sheath removal device according to one embodiment of the present invention; Figure 4 This is a schematic diagram of the cutting head in a fibrin sheath removal device in another embodiment of the present invention; Figure 5 This is a schematic diagram of the cutting head in a fibrin sheath removal device in another embodiment of the present invention; Figure 6 This is a schematic diagram of the cutting head in a fibrin sheath removal device in another embodiment of the present invention; Figure 7 This is a schematic diagram of the distal protection device in the fibrin sheath removal device in the embodiment of the present invention when it is in the retracted state; Figure 8 This is a schematic diagram of the distal protection device in the fibrin sheath removal device in the embodiment of the present invention when it is in the expanded state; Figure 9 This is a schematic diagram of the fibrin sheath removal device in use according to an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Tube body; 101. Hard section; 102. Cutting section; 1021. Hollowed-out structure; 103. Cutting head; 1031. Protrusion; 104. Quick exchange port; 2. Fasteners; 3. Handle; 4. Rotating components; 5. Remote protection device; 501. Frame; 502. Polymer membrane; 5021. Micropores; 6. Sleeve; 7. Central venous catheter. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and defined, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 like Figures 1 to 9 As shown, this embodiment provides a fibrin sheath removal device, including: a tube body 1, including a hard segment 101 located at the proximal end, a cutting segment 102 located at the distal end, and a cutting head 103 located at the end of the cutting segment 102, the cutting head 103 having a sharp blade; a quick exchange port 104 is provided on the side wall of the tube body 1; a fixing member 2 is disposed in the tube body 1, the distal end of the fixing member 2 extends out from the quick exchange port 104 for fixing a central venous catheter 7 located in the cutting segment 102, the proximal end of the fixing member 2 extending through the proximal end of the tube body 1.

[0023] In this embodiment, the fibrin sheath removal device is used by placing the cutting segment 102 around the central venous catheter 7 whose fibrin sheath is to be removed. The proximal end of the central venous catheter 7 is exposed at the quick exchange port 104 and fixed by the fixing member 2 to prevent the central venous catheter 7 from moving during the removal process. Then, the cutting head 103 is used to peel off the fibrin sheath outside the central venous catheter 7.

[0024] In this embodiment, the overall length of the tube 1 can be selected according to clinical needs, typically from 60cm to 120cm, to accommodate different patient heights and puncture sites. The length of the rigid segment 101 is typically 30cm to 50cm, made of materials with good anti-kink properties, such as medical-grade metal materials like 304 stainless steel, 316L stainless steel, and nickel-titanium alloy, or high-performance polymer materials like polyetheretherketone and polyimide. The outer diameter of the rigid segment 101 is typically 5Fr to 14Fr (1Fr≈0.33mm), and the inner diameter is 4Fr to 13Fr, to accommodate the central venous catheter 7 and pass through tortuous vascular pathways. The outer surface of the rigid segment 101 can be coated with a hydrophilic coating, such as polyvinylpyrrolidone or polyethylene glycol, to reduce frictional resistance during insertion and improve the device's passability. The proximal end of the rigid segment 101 is connected to the handle 3 or the rotating component 4, and the connection method can be adhesive bonding, heat shrink tubing fixation, threaded connection, or snap-fit ​​connection, ensuring sufficient connection strength to transmit rotational torque.

[0025] The length of the cutting segment 102 is typically 5cm to 15cm, and its outer diameter is basically the same as that of the hard segment 101. However, due to the use of a hollow structure, its radial flexibility is significantly improved. The hollow structure 1021 is formed on the tube body of the cutting segment 102 through laser cutting, electrical discharge machining, or mechanical cutting. The hollow structure 1021 can be various shapes such as spiral, rhombus, wave, or herringbone. The width of the connecting ribs between adjacent hollow units is 0.1mm to 0.5mm, and the hollowing rate (the proportion of hollow area to the total area) is 40% to 80%. This hollow structure allows the cutting segment 102 to conform to the natural curvature of the blood vessel while maintaining axial thrust, with a bending radius of 5mm to 10mm, thus enabling it to smoothly pass through tortuous parts such as the subclavian vein, brachiocephalic vein, and superior vena cava. The wall thickness of the cutting segment 102 is 0.1mm to 0.3mm to ensure sufficient cutting strength. The distal end of the cutting segment 102 is fixedly connected to the cutting head 103, and the connection method can be welding, bonding or integral molding.

[0026] The cutting head 103 is located at the distal end of the tube body 1, and its outer diameter is basically the same as or slightly larger than the outer diameter of the tube body 1 to form a smooth transition. The distal end of the cutting head 103 has a sharp blade for cutting the fibrin sheath. The blade of the cutting head 103 requires high hardness and is usually made of heat-treated stainless steel, tungsten carbide, or ceramic material with a Rockwell hardness of 45 to 60. The sharpness of the blade is required to easily cut fibrin sheath tissue with a thickness of 1-2 mm without damaging the central venous catheter 7 below. The axial length of the cutting head 103 can be 2 mm to 8 mm, and its inner diameter matches the outer diameter of the central venous catheter 7, usually being 0.2 mm to 0.8 mm larger than the outer diameter of the central venous catheter 7, so as to fit over the central venous catheter 7. The inner wall of the cutting head 103 can be coated, such as with polytetrafluoroethylene, to reduce friction with the central venous catheter 7.

[0027] The quick-exchange port 104 is located on the side wall of the tube body 1, preferably at the junction of the hard segment 101 and the cutting segment 102. This location facilitates external operation by the operator. The quick-exchange port 104 can be elliptical, rectangular, or circular in shape, with its major axis parallel to the axis of the tube body 1, a length of 5 mm to 15 mm, and a width of 2 mm to 5 mm. The edges of the quick-exchange port 104 are rounded to prevent sharp edges from damaging the inner wall of the blood vessel or the cutting fixation element 2. The function of the quick-exchange port 104 is to provide an opening at the proximal end of the device, allowing the central venous catheter 7 to be withdrawn from inside the tube body 1 at this location, thereby enabling a quick exchange operation. This quick-exchange structure design allows the operator to complete the insertion and withdrawal of the device without changing the guidewire, simplifying the operation process and shortening the operation time.

[0028] The fixation element 2 is disposed inside the tube body 1, with its distal end extending from the quick exchange port 104, for securing the central venous catheter 7 located within the cutting section 102. The proximal end of the fixation element 2 extends through the proximal end of the tube body 1 and is fixedly connected to the handle 3. The fixation element 2 can be made of metal wire, nickel-titanium alloy wire, or polymer fiber, with a diameter of 0.2 mm to 0.6 mm, possessing sufficient axial stiffness to transmit the fixing force, while also having a certain degree of flexibility to conform to the bending of the tube body 1. A connector can be provided at the distal end of the fixation element 2, and the shape of the connector can be conical, spherical, or cylindrical, with its outer diameter matching the inner diameter of the central venous catheter 7. In a preferred embodiment, the distal connector of the fixation element 2 has a conical structure, with its maximum outer diameter being 0.05 mm to 0.2 mm larger than the inner diameter of the central venous catheter 7, achieving a fixed connection with the central venous catheter 7 through an interference fit. The connector can be made of medical-grade silicone, polyurethane, or thermoplastic elastomer to provide good friction and cushioning, preventing damage to the inner wall of the central venous catheter 7. In another embodiment, the distal end of the fixation member 2 is provided with a threaded structure, which can be rotated to form a threaded connection with the inner wall of the central venous catheter 7 for a more secure fixation. The middle section of the fixation member 2 is located inside the tube body 1, and its surface can be provided with a lubricating coating, such as a polytetrafluoroethylene coating or a silicone oil coating, to reduce friction with the inner wall of the tube body 1, ensuring that the fixation member 2 can slide freely inside the tube body 1, thereby accommodating central venous catheters 7 of different lengths.

[0029] The fibrin sheath removal device also includes a handle 3, on which a rotating component 4 is provided. The proximal end of the tube body 1 is connected to the rotating component 4, and rotating the rotating component 4 can drive the tube body 1 to rotate. The proximal end of the fixing component 2 is fixed to the handle 3. The handle 3 is ergonomically designed, typically cylindrical or elliptical, with a length of 8cm to 12cm and a maximum diameter of 2cm to 3cm. The surface is provided with anti-slip textures or a silicone coating to facilitate grip and operation. The handle 3 can be injection molded from medical-grade polymer materials such as polycarbonate or acrylonitrile-butadiene-styrene copolymer. The rotating component 4 is located at the distal end or side of the handle 3, and its structure can be in the form of a knob, a roller, or a rocker arm. In a preferred embodiment, the rotating component 4 is a knob coaxially located at the distal end of the handle 3. The outer diameter of the knob is 2cm to 3cm, and the surface is provided with raised and recessed textures to increase friction. The knob is fixedly connected to the proximal end of the tube body 1, and rotating the knob can drive the tube body 1 to rotate. A bearing, such as a ball bearing or a sliding bearing, is provided between the rotating component 4 and the handle 3 to ensure smooth and uninterrupted rotation. The rotation angle of the rotating component 4 is unrestricted; it can rotate continuously or be set to rotate a certain angle each time with positioning feedback. The proximal end of the fixing component 2 is fixed to the inside or surface of the handle 3 by means of adhesive, snap-fit, or screw connection, allowing the operator to control the axial position of the fixing component 2 through the handle 3, thereby controlling the position of the central venous catheter 7 within the cutting segment 102.

[0030] like Figure 3 As shown, in another embodiment, the cutting head 103 has a flat-headed blade. A flat-headed blade is characterized by a smooth cutting surface, suitable for axial cutting of fibrous sheaths, and capable of uniformly stripping away the fibrous sheath tissue. The cutting edge angle of a flat-headed blade is typically 15° to 30°, and the cutting edge width is 0.1 mm to 0.3 mm. The flat-headed blade can be manufactured using methods such as grinding, electrochemical polishing, or laser cutting to ensure the sharpness and uniformity of the cutting edge.

[0031] like Figure 4 As shown, in another embodiment, the cutting head 103 has a serrated blade. The serrated blade is characterized by high cutting efficiency; the tooth height is 0.2 mm to 0.8 mm, the tooth pitch is 0.5 mm to 1.5 mm, and the shape of each tooth can be triangular, trapezoidal, or arc-shaped. During rotary cutting, the serrated blade generates intermittent cutting force, effectively reducing cutting resistance and facilitating the separation and removal of fibrin sheath tissue. The serrated blade is particularly suitable for fibrin sheaths with greater thickness (>2 mm) or more severe calcification.

[0032] like Figure 5 As shown, in another embodiment, the cutting head 103 has a pointed blade. The pointed blade is characterized by good guidance, enabling precise positioning of the cutting initiation point, and is suitable for establishing a cutting plane between the fibrin sheath and the vessel wall. The tip angle of the pointed blade is 20° to 45°, and the tip radius is less than 0.05 mm. The pointed blade can be coaxial with the axis of the tube body 1, or it can be configured as an eccentric structure to facilitate precise cutting in a specific direction.

[0033] like Figure 6 As shown, in another embodiment, the inner wall of the cutting head 103 is provided with a protrusion 1031. Changing the height of the protrusion 1031 controls the distance between the blade and the central venous catheter 7. The number of protrusions 1031 can be one or more. When multiple protrusions 1031 are provided, they can be evenly distributed circumferentially or spaced apart axially. The height of the protrusion 1031 is 0.05 mm to 0.5 mm, and the width is 0.1 mm to 1.0 mm. The protrusion 1031 contacts the outer surface of the central venous catheter 7, serving as a guide and limiting element to prevent the blade from cutting into the wall of the central venous catheter 7 and causing damage. By selecting protrusions 1031 of different heights, central venous catheters 7 with different outer diameters can be adapted, improving the versatility of the device. The protrusion 1031 can be an integrally formed structure with the cutting head 103, or it can be a separate component fixed by welding or bonding. The surface of the protrusion 1031 can be coated with a low-friction coating, such as polytetrafluoroethylene or diamond-like carbon coating, to reduce friction with the central venous catheter 7.

[0034] The tube body 1 of the cutting segment 102 is cut with a perforated structure 1021. The perforated structure 1021 not only improves the flexibility of the cutting segment 102, but also has the following functions: First, the perforated structure 1021 makes the cutting segment 102 have good radiolucency, and the position and shape of the cutting segment 102 can be clearly displayed under X-ray fluoroscopy, which is convenient for the operator to accurately position it; Second, the perforated structure 1021 provides a channel for the discharge of fibrin sheath fragments. The fibrin sheath fragments stripped by the cutting head 103 can enter the interior of the tube body 1 or be discharged to the exterior of the tube body 1 through the perforated structure 1021, preventing the accumulation of fragments from affecting the cutting effect; Third, the perforated structure 1021 gives the cutting segment 102 a certain radial expansion capacity, which can adapt to central venous catheters 7 with different outer diameters. The pattern of the 1021 hollow structure can be selected as needed. For example, the spiral hollow structure has good flexibility and anti-kink performance, making it suitable for curved paths; the diamond hollow structure has good axial thrust and torque transmission performance, making it suitable for scenarios requiring precise positioning; the herringbone hollow structure has bidirectional flexibility and can adapt to bending in both directions.

[0035] The quick-change port 104 is located at the intersection of the hard segment 101 and the cutting segment 102. This location offers several advantages: First, the intersection of the hard segment 101 and the cutting segment 102 is a transitional area in the device's structural performance, and placing the quick-change port 104 here will not significantly affect the device's mechanical properties. Second, this location is a certain distance from the cutting head 103, ensuring that the distal end of the fixation member 2 can extend from the quick-change port 104 and fix the proximal end of the central venous catheter 7, while the distal end of the central venous catheter 7 is located inside the cutting segment 102, facilitating the cutting operation. Third, this location is close to the handle 3, making it convenient for the operator to perform the operation externally. The edge of the quick-change port 104 can be marked with radiopaque markers, such as a platinum-iridium alloy ring or a gold ring, to accurately locate the quick-change port 104 under X-ray fluoroscopy.

[0036] The fibrin sheath removal device also includes a distal protection device 5, adapted to be placed distal to the central venous catheter 7, to collect the fibrin sheath removed by the cutting head 103 and prevent the fibrin sheath from migrating downstream of the blood vessel and causing secondary damage. The distal protection device 5 is a relatively independent component from the catheter body 1, and is inserted into the blood vessel before the catheter body 1 during use, located distal to the central venous catheter 7. The design of the distal protection device 5 fully considers the vascular anatomy and hemodynamic characteristics, enabling effective collection of fibrin sheath fragments while minimizing the impact on blood flow.

[0037] The distal protection device 5 is a radially contractible and self-expanding conical structure. This design allows the distal protection device 5 to be constricted to a smaller diameter (e.g., 2Fr to 5Fr) by the cannula 6 during delivery, facilitating passage through the blood vessel path. Upon reaching the predetermined position, the cannula 6 is removed, and the distal protection device 5 automatically expands to a larger diameter (e.g., 10Fr to 20Fr) due to its own elastic recovery force, forming a good fit with the blood vessel wall and thus creating a filtering barrier within the blood vessel lumen. The self-expanding characteristic of the distal protection device 5 can be achieved using superelastic materials such as nickel-titanium alloys. The austenitic transformation temperature of nickel-titanium alloys is 25°C to 37°C, allowing them to completely recover their preset shape under body temperature conditions. The conical structure design allows fibrin sheath fragments to be collected inside the cone, while blood can continue to flow through the micropores 5021 on the cone, preventing vascular occlusion.

[0038] like Figure 7 , Figure 8 As shown, the remote protection device 5 is initially confined in a retracted state by the sleeve 6. When the remote protection device 5 is released from the sleeve 6, it automatically opens into an expanded state. The sleeve 6 is a thin-walled tubular structure, with an inner diameter slightly larger than the outer diameter of the remote protection device 5 in its retracted state, typically 2.5Fr to 5.5Fr, and a wall thickness of 0.05mm to 0.15mm. The sleeve 6 can be made of low-friction polymer materials such as polytetrafluoroethylene, high-density polyethylene, or polyetheretherketone to facilitate the pushing and releasing of the remote protection device 5. The proximal end of the sleeve 6 is connected to a push rod or handle; the release or retrieval of the remote protection device 5 is achieved by axially moving the sleeve 6.

[0039] like Figure 8As shown, the distal protection device 5 includes a skeleton 501 and a polymer membrane 502 disposed on the skeleton 501, the polymer membrane 502 having micropores 5021. The skeleton 501 is woven or cut from nickel-titanium alloy wire to form a conical mesh structure. The wire diameter of the skeleton 501 is 0.05 mm to 0.2 mm, and the mesh size is 0.5 mm to 3 mm, maintaining sufficient support while having good flexibility. The distal end of the skeleton 501 can be provided with a blunt tip to prevent damage to the blood vessel wall. The polymer membrane 502 covers the outer or inner surface of the skeleton 501, and its material can be medical-grade polymer materials such as polyurethane, silicone rubber, or polytetrafluoroethylene, with a thickness of 0.01 mm to 0.05 mm. The micropores 5021 on the polymer membrane 502 have a pore size of 50 μm to 300 μm. This size allows red blood cells (approximately 7 μm in diameter) and platelets (approximately 2-4 μm in diameter) to pass through, while effectively intercepting fibrin sheath debris (typically larger than 0.5 mm in diameter), thus achieving selective filtration. The distribution of micropores 5021 can be uniform or designed as a gradually varying distribution based on hemodynamic analysis results to improve filtration efficiency and reduce transmembrane pressure gradient. Micropores 5021 can be formed using methods such as laser drilling, electrical discharge machining, or template methods.

[0040] In another alternative embodiment, the distal protection device 5 can adopt an umbrella-shaped structure, consisting of multiple support ribs and a filter membrane covering the support ribs. The number of support ribs is 4 to 12, made of nickel-titanium alloy or medical-grade stainless steel, and the material and microporous structure of the filter membrane are similar to the aforementioned polymer membrane 502. The umbrella-shaped distal protection device 5 is cylindrical in its folded state and umbrella-shaped when expanded, resulting in a smaller contact area with the blood vessel wall and less irritation to the vascular endothelium.

[0041] In another alternative implementation, the distal protection device 5 can be a balloon-expandable structure, whereby the distal protection device 5 is positioned outside the balloon, and is deployed and attached to the vessel wall by balloon expansion. The advantage of this structure is that the degree of expansion can be precisely controlled according to the vessel diameter, making it suitable for patients with significant variations in vessel diameter.

[0042] like Figure 9 As shown, the method of using the fibrin sheath removal device in this embodiment is as follows: First, vascular access is established using vascular puncture techniques, typically selecting the femoral vein, internal jugular vein, or subclavian vein as the puncture site. Under X-ray fluoroscopy guidance, a guidewire is inserted into the blood vessel along the puncture site, passing through the distal end of the central venous catheter 7, to reach the appropriate location in the superior or inferior vena cava.

[0043] Next, the distal protection device 5 is advanced along the guidewire to the distal end of the central venous catheter 7, specifically 2 to 5 cm downstream of the distal end of the central venous catheter 7. After confirming the accurate positioning of the distal protection device 5 using X-ray fluoroscopy, the cannula 6 is removed. The distal protection device 5 automatically opens due to its own elastic restoring force, and the dilated distal protection device 5 adheres to the vessel wall. At this point, the guidewire can be withdrawn.

[0044] Next, the fibrin sheath removal device of this embodiment is inserted into the body along the external segment of the central venous catheter 7. Specifically, the cutting segment 102 of the fibrin sheath removal device tube 1 is fitted over the outside of the central venous catheter 7 and pushed along the central venous catheter 7 until the cutting head 103 reaches the distal end of the fibrin sheath. During the pushing process, the proximal end of the central venous catheter 7 is exposed from the quick exchange port 104. The operator uses the distal end of the fixation member 2 to fix the proximal end of the central venous catheter 7. For example, the tapered connector at the distal end of the fixation member 2 is inserted into the lumen of the central venous catheter 7 and pressed tightly to fix the central venous catheter 7 to the fixation member 2.

[0045] Then, the operator holds the handle 3 with one hand for stability, and rotates the rotating part 4 on the handle 3 with the other hand, causing the tube body 1 to rotate, which in turn causes the cutting head 103 of the tube body 1 to rotate. During rotation, the sharp blade of the cutting head 103 contacts the fibrin sheath on the outer surface of the central venous catheter 7, peeling it off layer by layer. The operator can slowly move the handle 3 axially while rotating, allowing the cutting head 103 to move along the central venous catheter 7 from distal to proximal, achieving continuous peeling of the fibrin sheath. During the cutting process, some of the peeled fibrin sheath fragments are discharged through the perforated structure 1021 on the cutting section 102, while the other part moves downstream with the blood flow and is captured and collected by the distal protection device 5, which is pre-placed at the distal end. The micropores 5021 on the distal protection device 5 allow blood to pass through normally while intercepting the fibrin sheath fragments inside the conical structure.

[0046] After the fibrin sheath on the outer surface of the central venous catheter 7 has been completely removed, the operator removes the fixation device 2 from the central venous catheter 7 and removes it from the body. If a new central venous catheter needs to be replaced, it can be inserted via a guidewire or directly. Finally, the entire fibrin sheath removal device, along with the distal protection device 5, is withdrawn from the body. When withdrawing the distal protection device 5, the retrieval cannula (similar in structure to cannula 6) can be first advanced along the push rod to the proximal end of the distal protection device 5. Then, the retrieval cannula is pushed forward to retract the distal protection device 5 into the retrieval cannula, making it retracted. Finally, the retrieval cannula and the distal protection device 5 are withdrawn from the body.

[0047] During the procedure, the operator should monitor the position and status of the device in real time using X-ray fluoroscopy to ensure that the cutting head 103 remains on the outer surface of the central venous catheter 7, thus avoiding damage to the vessel wall. Simultaneously, the filtration status of the distal protection device 5 should be carefully observed. If a large amount of fibrin sheath fragments collected by the distal protection device 5 is found to be affecting blood flow, it should be promptly retrieved or replaced with a new distal protection device 5.

[0048] Example 2 The difference between this embodiment and Embodiment 1 is that the distal end of the fixation member 2 is provided with an expandable anchoring structure, such as a balloon or an expandable cage structure. When fixing the central venous catheter 7, the anchoring structure is expanded by injecting fluid or mechanical expansion, forming a tight contact with the inner wall of the central venous catheter 7, thereby achieving more reliable fixation. This anchoring structure is particularly suitable for situations where the inner wall of the central venous catheter 7 is smooth and has low friction. The expansion medium can be a mixture of physiological saline or contrast agent, and the position and degree of expansion of the anchoring structure can be clearly shown under X-ray fluoroscopy. After the cutting operation is completed, the expansion medium is withdrawn, the anchoring structure returns to its contracted state, and the fixation member 2 can be removed from the central venous catheter 7.

[0049] Example 3 The difference between this embodiment and Embodiment 1 is that the hollow structure 1021 of the cutting segment 102 is variable, meaning the shape of the hollow structure 1021 can be changed through mechanical control. For example, a control wire is installed inside the tube body 1, with its distal end connected to the distal end of the cutting segment 102. By pulling the control wire, the degree of bending and radial stiffness of the hollow structure 1021 can be changed, thereby increasing the rigidity of the cutting segment 102 to facilitate cutting when needed, or increasing its flexibility to facilitate passage through tortuous blood vessels when needed. This adjustable hollow structure allows the device to adapt to different vascular anatomy conditions and surgical requirements.

[0050] Example 4 The difference between this embodiment and Embodiment 1 is that the cutting head 103 has a detachable or replaceable blade to accommodate fibrin sheaths of varying thicknesses and hardnesses. For example, a flat-edged blade with a smaller cutting angle can be selected for thinner, softer fibrin sheaths; a serrated blade can be selected for thicker, harder fibrin sheaths; and a ceramic blade with higher hardness can be selected for severely calcified fibrin sheaths. The cutting head 103 is connected to the tube body 1 by a threaded or snap-fit ​​connection for easy and quick replacement. This modular design improves the adaptability and economy of the device.

[0051] Example 5 The difference between this embodiment and Embodiment 1 is that a flushing channel is provided inside the tube body 1 for delivering physiological saline or heparinized saline to the cutting area. The flushing channel can be an independent cavity within the wall of the tube body 1, with its proximal end connected to the flushing interface and its distal end opening near the cutting head 103. During the cutting process, the continuous or intermittent delivery of flushing fluid through the flushing channel serves the following purposes: First, the flushing fluid lubricates the cutting interface, reducing cutting resistance; second, the flushing fluid washes away the cut fibrin sheath fragments, preventing their accumulation at the cutting head 103 and affecting the cutting effect; third, the anticoagulant components such as heparin in the flushing fluid inhibit thrombus formation, reducing the risk of complications. The flow rate of the flushing fluid is typically 1 ml / min to 5 ml / min and can be adjusted in real time according to the cutting status.

[0052] Example 6 The difference between this embodiment and Embodiment 1 is that the surfaces of the cutting segment 102 and the cutting head 103 are coated with a bioactive coating, such as a heparin coating, an anti-proliferative drug coating (such as rapamycin, paclitaxel, etc.), or an endothelial cell trapping coating (such as an anti-CD34 antibody coating). The heparin coating can inhibit thrombus formation and reduce the incidence of catheter-related thrombosis; the anti-proliferative drug coating can inhibit fibrin sheath reformation and prolong the patency time of newly inserted catheters; the endothelial cell trapping coating can promote vascular endothelial repair and restore normal vascular physiological function. The drug loading capacity of the bioactive coating can be designed as needed to achieve sustained drug release.

[0053] Example 7 The difference between this embodiment and Embodiment 1 is that the skeleton 501 and the polymer membrane 502 of the remote protection device 5 are an integrated structure. That is, the polymer membrane 502 is directly coated onto the surface of the skeleton 501, forming a non-porous integral structure, but micropores 5021 are still retained on the polymer membrane 502. The advantages of this integrated structure are its simplicity, low manufacturing cost, and high bonding strength between the polymer membrane 502 and the skeleton 501, making it less prone to detachment. The polymer membrane 502 can be coated using methods such as dip coating, spray coating, or electrospinning, and its thickness can be precisely controlled.

[0054] Example 8 The difference between this embodiment and Embodiment 1 is that the remote protection device 5 is provided with imaging markers, such as platinum-iridium alloy rings, gold rings, or tantalum wires, to accurately locate the position of the remote protection device 5 under X-ray fluoroscopy. The imaging markers can be set at the proximal, distal, or intermediate position of the frame 501, and multiple imaging markers can be set simultaneously to indicate the direction and orientation of the remote protection device 5. The imaging markers are 0.2 mm to 1.0 mm in size and can be fixed to the frame 501 by welding, pressing, or bonding.

[0055] Example 9 The difference between this embodiment and Embodiment 1 is that the distal protection device 5 has a retrieval function. That is, after completing the collection of the fibrin sheath, the distal protection device 5 can be completely retrieved into the retrieval sleeve and withdrawn from the body along with the tube body 1. The inner diameter of the retrieval sleeve is slightly larger than the expanded outer diameter of the distal protection device 5, and the wall thickness is 0.1 mm to 0.2 mm. A locking mechanism is provided between the retrieval sleeve and the push rod to ensure that the distal protection device 5 will not accidentally dislodge during retrieval. A radiopaque marker can be provided at the distal end of the retrieval sleeve for easy positioning.

[0056] Example 10 The difference between this embodiment and Embodiment 1 is that the handle 3 is also equipped with a torque sensor and an angle sensor, which are used to monitor the torque and rotation angle of the rotating component 4 in real time and transmit the data to an external display device. The operator can determine the contact state between the cutting head 103 and the fibrin sheath based on the displayed torque value. If the torque is too high, it indicates that the cutting resistance may be too great, requiring adjustment of the cutting speed or direction; if the torque suddenly drops, it indicates that the fibrin sheath has been completely cut. The angle sensor can record the cumulative number of rotations of the rotating component 4, used to estimate the cutting length and cutting efficiency. This intelligent design improves the controllability and safety of the operation.

[0057] In summary, current treatments for catheter dysfunction caused by fibrin sheaths often involve catheter replacement. However, even with in-situ catheter replacement, catheter dysfunction can still occur because the catheter may become trapped within the fibrin sheath. While balloon dilation of the fibrin sheath before catheter replacement may improve function in the short term, long-term patency remains low, and there is a risk of pulmonary embolism due to sheath tearing and detachment during balloon dilation. Changing the catheter insertion site can reduce vascular resources, and residual fibrin sheath can easily adhere to blood vessels, leading to central venous occlusion. To address these drawbacks, the fibrin sheath removal device described in this application effectively removes the fibrin sheath during catheter replacement for central venous catheter dysfunction caused by fibrin sheath, prolonging the patency of the newly inserted catheter. Furthermore, the distal protection device 5 prevents the fibrin sheath from detaching into the pulmonary artery and causing pulmonary embolism.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to cover all possible implementations. Those skilled in the art will recognize that various variations and modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations and modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A fibrin sheath removal device, characterized in that, include: The tube body (1) includes a hard segment (101) located at the proximal end, a cutting segment (102) located at the distal end, and a cutting head (103) located at the end of the cutting segment (102), the cutting head (103) having a sharp blade; a quick exchange port (104) is provided on the side wall of the tube body (1). A fixation element (2) is disposed inside the tube body (1), the distal end of the fixation element (2) extends from the quick exchange port (104) for fixing the central venous catheter (7) located in the cut section (102), and the proximal end of the fixation element (2) extends through the proximal end of the tube body (1).

2. The fibrin sheath removal device according to claim 1, characterized in that, It also includes a handle (3), on which a rotating part (4) is provided. The proximal end of the tube body (1) is connected to the rotating part (4). By rotating the rotating part (4), the tube body (1) can be rotated. The proximal end of the fastener (2) is fixed to the handle (3).

3. The fibrin sheath removal device according to claim 1, characterized in that, The cutting head (103) has a flat, serrated, or pointed blade shape.

4. The fibrin sheath removal device according to claim 1, characterized in that, The inner wall of the cutting head (103) is provided with a protrusion (1031), and the distance between the blade and the central venous catheter (7) can be controlled by changing the height of the protrusion (1031).

5. The fibrin sheath removal device according to claim 1, characterized in that, The cut section (102) has a hollow structure (1021) cut into the tube body (1).

6. The fibrin sheath removal device according to claim 1, characterized in that, The fast exchange port (104) is located at the intersection of the hard segment (101) and the cutting segment (102).

7. The fibrin sheath removal device according to any one of claims 1-6, characterized in that, It also includes a distal protection device (5) adapted to be placed at the distal end of the central venous catheter (7) to collect the fibrin sheath cleared by the cutting head (103).

8. The fibrin sheath removal device according to claim 7, characterized in that, The remote protection device (5) is a conical structure that can be radially contracted and self-expanding.

9. The fibrin sheath removal device according to claim 8, characterized in that, The remote protection device (5) is initially bound by the sleeve (6) in a retracted state, and automatically opens into an expanded state after being released from the sleeve (6).

10. The fibrin sheath removal device according to claim 7, characterized in that, The remote protection device (5) includes a frame (501) and a polymer membrane (502) disposed on the frame (501), wherein the polymer membrane (502) is provided with micropores (5021).

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