A central venous catheter

Abstract

The application discloses a central venous catheter, which comprises an inner tube, an outer tube axially movably sleeved outside the inner tube and a filter arranged at the distal end of the inner tube; the filter comprises a proximal end connecting part, a distal end connecting part and a plurality of support units; each support unit comprises a proximal end support rod, a support cross beam and a distal end support rod which are sequentially connected between the proximal end connecting part and the distal end connecting part; in a fully unfolded state of the filter, a tangent line of the proximal end support rod at the connection with the proximal end connecting part and towards the support cross beam forms an acute angle alpha with the pressure conveying direction; a tangent line of the proximal end support rod at the connection with the support cross beam and towards the proximal end connecting part forms an obtuse angle beta with the extension direction of the support cross beam towards the distal end support rod, so that the outer tube is pressed to fold the proximal end support rod towards the inner tube when moving along the pressure conveying direction, and the filter is compressed and stored in the outer tube. The application can make the outer tube axially move to press the filter to fold radially and be compressed and stored in the outer tube, and improve the smoothness and stability of filter recovery.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a central venous catheter. Background Technology

[0002] Central venous catheters are mainly used for intravenous infusion, blood collection, and central venous pressure monitoring, while vena cava filters are mainly used to intercept venous thrombi and prevent them from entering the pulmonary circulation. Currently, central venous catheters and vena cava filters are usually independent devices. For patients who need to establish central venous access but are at risk of thromboembolism, separate catheter placement and filter implantation procedures are usually required, increasing the number of interventional procedures, the risk of vascular injury, and treatment costs.

[0003] Furthermore, existing recyclable filters require conveying or retrieval equipment to retract the unfolded filter during the retrieval process. Due to the unreasonable shape and stress relationship of the filter support structure, problems such as excessive local stress, folding interference, or unsmooth retraction can easily occur during retrieval, making it difficult for the filter to enter the retrieval equipment stably. In some cases, filter deformation, retrieval jamming, and damage to the blood vessel wall may even occur, affecting the safety and success rate of the operation.

[0004] Therefore, how to ensure that the filter can be smoothly and stably retracted while having both central venous access and thrombus filtration functions is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a central venous catheter that can compress and store the filter radially within the outer tube when the outer tube moves axially, thereby improving the smoothness and stability of filter retrieval and reducing folding interference and jamming during the retrieval process.

[0006] To achieve the above objectives, this application provides a central venous catheter, including an inner tube, an outer tube axially movable and sleeved outside the inner tube, and a filter disposed at the distal end of the inner tube;

[0007] The filter includes a proximal connection fixedly disposed on the inner tube, a distal connection movable along the axial direction of the inner tube, and a plurality of support units distributed along the circumference of the inner tube; each support unit includes a proximal support rod, a support beam, and a distal support rod sequentially connected between the proximal connection and the distal connection.

[0008] With the direction from the proximal connector to the distal connector as the pressing direction, in the fully extended state of the filter, the tangent of the proximal support rod at its connection with the proximal connector towards the support beam forms an acute angle α with the pressing direction; the tangent of the proximal support rod at its connection with the support beam towards the proximal connector forms an obtuse angle β with the extension direction of the support beam towards the distal support rod. When the outer tube moves along the pressing direction, it compresses the proximal support rod towards the inner tube and drives the distal connector to move axially, thereby compressing and housing the filter inside the outer tube.

[0009] Optionally, in the fully deployed state of the filter, the proximal support rod is in an arc shape that bends toward the central axis of the inner tube, and the middle part of the proximal support rod is located on the side of the line connecting its two ends close to the central axis.

[0010] Optionally, in the fully deployed state of the filter, the tangent of the distal support rod at its connection with the distal connection portion toward the support beam forms an acute angle θ with the direction opposite to the pressing direction; the tangent of the distal support rod at its connection with the support beam toward the distal connection portion forms an obtuse angle γ with the direction of extension of the support beam toward the proximal support rod.

[0011] The acute angle α and the acute angle θ are 20°-60°, and the obtuse angle β and the obtuse angle γ are 95°-150°.

[0012] Optionally, the inner tube is a variable diameter tube comprising interconnected large-diameter and small-diameter sections, and the inner tube has a through central venous access lumen.

[0013] The proximal connection is fixed to the distal end of the large-diameter pipe section and adjacent to the small-diameter pipe section, and the distal connection is axially movable and sleeved on the small-diameter pipe section.

[0014] In the overlapping area where the outer tube is sleeved outside the small-diameter pipe section, an annular radial gap is formed between the outer wall of the small-diameter pipe section and the inner wall of the outer tube, and the filter is radially compressed and housed in the radial gap.

[0015] Optionally, both the proximal connection and the distal connection are cylindrical, and at least one of them has a recovery groove on its outer peripheral wall. The recovery groove is an annular groove that extends continuously in the circumferential direction or an arc-shaped groove that extends partially in the circumferential direction. The filter is integrally formed from shape memory alloy, and the exposed edges of the proximal connection, the distal connection, and the support unit, as well as the parts for contacting the blood vessel wall, are all smooth transition structures.

[0016] Optionally, the outer tube has a flared opening at its distal end, with both its inner and outer surfaces having rounded transitions. The angle φ between the generatrix of the inner surface of the flared opening and the central axis of the outer tube is 30°-75°. The inner tube has a pointed tip at its distal end. When the filter is retracted into place, the pointed tip abuts against the opposite end face of the flared opening, and the maximum outer diameter of the distal end of the flared opening is the same as the maximum outer diameter of the pointed tip.

[0017] Optionally, the outer tube includes a flexible tube body, the wall of which is embedded with a spring support layer, the spring support layer being spirally wound along the axial direction of the outer tube, and the outer wall of the flexible tube body is provided with an anti-condensation coating.

[0018] Optionally, the supporting beam is provided with a plurality of dispersion holes penetrating the supporting beam, and the axis of the dispersion holes extends radially along the inner tube; the dispersion holes are round holes or elongated holes, and when the dispersion holes are elongated holes, their long axis direction or length direction is consistent with the extension direction of the supporting beam.

[0019] Optionally, the outer surface of the tip is rounded and has no sharp edges, and a developing ring is embedded therein. The outer diameter of the developing ring is smaller than the outer diameter of the tip. When the tip abuts against the flared opening, the developing ring is accommodated inside the outer tube.

[0020] Optionally, in the fully extended state of the filter, the length of each of the supporting beams is 1mm-20mm, and the maximum outer diameter of the filter is 20mm-32mm.

[0021] The beneficial effects of this application are that by placing the filter at the distal end of the inner tube of a central venous catheter and using an outer tube sleeved over the inner tube to compress and store the filter, the central venous access function and thrombus filtration function are integrated into a single device. This reduces the interventional procedures required for separate placement of the central venous catheter and the vena cava filter, improving the ease of use of the device. Simultaneously, the proximal connector of the filter is fixed to the inner tube, while the distal connector can move axially along the inner tube. When the outer tube moves along the delivery direction, the acute and obtuse angles at both ends of the proximal support rod create a pressure on the proximal support rod towards the inner tube, causing the support units to retract radially and simultaneously driving the distal connector to move axially. This allows the filter to gradually transition from an unfolded state to a compressed state and be stored within the outer tube. This structure reduces folding interference and jamming during filter retraction, making the filter compression path more stable and improving the smoothness of filter retrieval and operational safety. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the central venous catheter provided in the embodiment of this application with the filter fully deployed.

[0024] Figure 2 This is a schematic diagram of the fully deployed state of the filter provided in the embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the central venous catheter provided in the embodiment of this application in the filter compression state;

[0026] Figure 4 This is a schematic diagram of the structure in which the tip of the end abuts against the flared opening, as provided in an embodiment of this application.

[0027] In the diagram: 1-Inner tube; 2-Filter; 3-Outer tube; 4-End tip; 5-Developing ring;

[0028] 11 - Small-diameter pipe section; 12 - Large-diameter pipe section;

[0029] 21-Proximal support rod; 22-Distal support rod; 23-Support beam; 24-Dispersion hole; 25-Proximal connection part; 26-Distal connection part; 27-Recovery trough;

[0030] 31-Flare mouth; 32-Spring support layer; 33-Anti-condensation coating. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "upper," "lower," "front," and "rear" is based on the orientation or positional relationship shown in the accompanying drawings. It is used only for the convenience of describing this application and for simplifying the description, and does 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, it should not be construed as a limitation of this application. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] like Figures 1 to 4 As shown, in this embodiment, a central venous catheter is provided, including an inner tube 1, a filter 2, and an outer tube 3. The outer tube 3 is sleeved outside the inner tube 1 and can reciprocate along the axial direction of the inner tube 1. The filter 2 is located in the distal region of the inner tube 1 and can switch between a fully extended state and a radially compressed state. In this embodiment, the distal end refers to the end closer to the lesion site, and the proximal end refers to the end closer to the operator or physician.

[0035] The inner tube 1 has a central venous access lumen running through it along its axis. This central venous access lumen can be a single lumen or it can form a multi-lumen structure with other lumens located proximal to the inner tube 1, for use in infusion, blood collection, or central venous pressure monitoring. The proximal end of the inner tube 1 can be connected to an infusion connector, a blood collection connector, or a pressure monitoring connector, and the specific connector type can be determined according to the usage requirements of the central venous catheter.

[0036] The filter 2 includes a proximal connection portion 25, a distal connection portion 26, and multiple support units spaced apart circumferentially along the inner tube 1. The proximal connection portion 25 is fixedly mounted on the inner tube 1 and cannot move axially relative to the inner tube 1. The proximal connection portion 25 and the inner tube 1 can be connected by heat fusion, adhesive bonding, wrapping fixation, crimping, or other connection structures that can restrict relative movement between the two.

[0037] The distal connection part 26 is sleeved on the inner tube 1 and can move along the axial direction of the inner tube 1. A sliding gap is maintained between the distal connection part 26 and the inner tube 1 so that the distal connection part 26 can move along the inner tube 1 when the filter 2 is unfolded or compressed, while avoiding significant radial shaking of the distal connection part 26.

[0038] Each support unit is distributed sequentially along the circumference of the inner tube. Each support unit includes a proximal support rod 21, a support beam 23, and a distal support rod 22 connected in sequence. Please refer to [reference needed]. Figure 2One end of the proximal support rod 21 is connected to the proximal connecting part 25, and the other end is connected to the support beam 23; one end of the distal support rod 22 is connected to the support beam 23, and the other end is connected to the distal connecting part 26.

[0039] When the filter 2 is fully deployed, multiple support units form a circumferential frame structure around the inner tube 1. The support beam 23 is located radially outside the filter 2, used to be close to the blood vessel wall and maintain the deployed outer diameter of the filter 2. The proximal support rod 21 and the distal support rod 22 are respectively connected to the two ends of the support beam 23 to form a support structure that can be radially opened and axially extended between the proximal connection 25, the distal connection 26 and the support beam 23.

[0040] Furthermore, in the fully deployed state of the filter 2, the proximal support rod 21 has a tangent towards the support beam 23 at its connection with the proximal connection portion 25, and this tangent forms an acute angle α with the pressing direction. The proximal support rod 21 also has a tangent towards the proximal connection portion 25 at its connection with the support beam 23, and this tangent forms an obtuse angle β with the extending direction of the support beam 23 towards the distal support rod 22.

[0041] When the outer tube 3 moves along the pressing direction, the far end of the outer tube 3 first contacts the proximal support rod 21. Since the tangent of the proximal support rod 21 at the proximal connection 25 forms an acute angle α with the pressing direction, the axial thrust applied by the outer tube 3 can generate a radial component force on the proximal support rod 21 toward the inner tube 1, causing the proximal support rod 21 to gradually retract toward the inner tube 1.

[0042] As the proximal support rod 21 radially retracts, the support beam 23 moves closer to the inner tube 1. The obtuse angle β between the proximal support rod 21 and the support beam 23 provides folding space, preventing them from abutting each other during the retraction process. The movement of the support beam 23 further drives the distal support rod 22 to retract and pushes the distal connecting part 26 to move distally along the inner tube 1. This results in a morphological change in the filter 2, with a decrease in radial dimension and an increase in axial length, until the filter 2 retracts into the outer tube 3.

[0043] When filter 2 is released, the position of inner tube 1 is fixed, and outer tube 3 moves in the opposite direction of the pressing direction. Outer tube 3 gradually releases the radial restriction on the support unit, and filter 2 returns to the preset fully extended state by its own elasticity. At the same time, distal connection 26 moves along inner tube 1 toward the proximal end.

[0044] In this embodiment, when the filter 2 is fully extended, the proximal support rod 21 is curved toward the central axis of the inner tube 1. Specifically, the straight line between the connection point of the proximal support rod 21 and the proximal connecting part 25 and the connection point of the proximal support rod 21 and the support beam 23 is taken as the line connecting the two ends, and the middle part of the proximal support rod 21 is located on the side of the line connecting the two ends closer to the central axis of the inner tube 1.

[0045] When the outer tube 3 moves along the pressing direction and contacts the proximal support rod 21, the distal end of the outer tube 3 slides along the arc-shaped structure of the proximal support rod 21 toward the support beam 23. After being pressed by the outer tube 3, the middle part of the arc-shaped support rod 21 continues to move closer to the inner tube 1, causing the proximal support rod 21 to bend in a predetermined direction without folding outward.

[0046] The arc shape of the proximal support rod 21 can be a single circular arc or formed by the continuous connection of multiple arc segments with different curvatures. The connection points of each arc segment are continuous curved surfaces without any bends. The part of the proximal support rod 21 near the proximal connection 25 can be set as an introductory section with a larger curvature, and the part near the support beam 23 can be set as a transition section with a smaller curvature, so that the axial thrust of the outer tube 3 is gradually converted into radial compressive force.

[0047] In a preferred embodiment, each proximal support rod 21 has the same arcuate profile and is evenly distributed around the inner tube 1, so that each proximal support rod 21 retracts substantially synchronously when the outer tube 3 is pressed. Depending on the wall-mounting requirements of the filter 2 at the bend of the blood vessel, the proximal support rods 21 at different circumferential positions may also have different curvatures, but each proximal support rod 21 maintains an arcuate shape that bends toward the central axis of the inner tube 1.

[0048] Furthermore, the distal support rod 22 is connected between the support beam 23 and the distal connection portion 26. When the filter 2 is fully deployed, the distal support rod 22 has a tangent towards the support beam 23 at its connection with the distal connection portion 26, and this tangent forms an acute angle θ with the direction opposite to the pressing direction. The distal support rod 22 also has a tangent towards the distal connection portion 26 at its connection with the support beam 23, and this tangent forms an obtuse angle γ with the extension direction of the support beam 23 towards the proximal support rod 21.

[0049] The acute angles α and θ are between 20° and 60°. When the acute angle is less than 20°, the support rod extends more axially along the inner tube 1, resulting in a smaller radial support force after the filter 2 is deployed. When the acute angle is greater than 60°, the bending deformation of the support rod during radial compression increases, and the thrust required for the outer tube 3 to pressurize increases accordingly. Therefore, setting the acute angles α and θ within the range of 20° to 60° allows the support rod to provide radial support during deployment and to gradually fold along the pressing direction of the outer tube 3 during retraction.

[0050] In a preferred embodiment, the acute angle α is 40° to 55°, and the acute angle θ is 30° to 45°. The proximal support rod 21 and the distal support rod 22 adopt different starting angles, so that the filter 2 forms different support directions on both sides of the axial direction. When there is a bend in the blood vessel, the proximal support rod 21 and the distal support rod 22 respectively restrict the position of the support beam 23 from both sides of the filter 2, reducing the overall tilt of the filter 2 to one side.

[0051] The obtuse angles β and γ are 95° to 150°, preferably 100° to 140°. This range of obtuse angles ensures that there are no acute-angle nodes protruding into the filter 2 between the support rod and the support beam 23. When the filter 2 is compressed, the proximal support rod 21 and the distal support rod 22 can move closer to the inner tube 1 respectively, and the support beam 23 can remain between them, reducing the possibility of the support rod and the support beam 23 crossing or abutting each other.

[0052] Acute angles α, θ, β, and γ are all measured with the filter 2 unconstrained by the outer tube 3 and fully extended. For support rods with arc-shaped profiles, the tangent in the specified direction at the corresponding connection is used as the angle measurement reference.

[0053] The inner pipe 1 is a reducing pipe, comprising interconnected small-diameter pipe section 11 and large-diameter pipe section 12. Please refer to... Figure 1 The small-diameter tube segment 11 is located at the distal end of the inner tube 1, and the large-diameter tube segment 12 is located at the proximal end of the small-diameter tube segment 11. The central venous access lumens inside the small-diameter tube segment 11 and the large-diameter tube segment 12 are interconnected.

[0054] The outer diameter of the small-diameter pipe section 11 is smaller than that of the large-diameter pipe section 12. The junction between the small-diameter pipe section 11 and the large-diameter pipe section 12 can be a stepped transition, or a conical or arc-shaped transition. To reduce the resistance generated when the fluid passes through the inner pipe 1, the inner walls of the small-diameter pipe section 11 and the large-diameter pipe section 12 preferably adopt a continuous transition structure.

[0055] The proximal connector 25 is fixed to the distal end of the large-diameter pipe section 12 and adjacent to the small-diameter pipe section 11. The proximal connector 25 can be sleeved on the outside of the large-diameter pipe section 12. After the proximal connector 25 is fixed to the inner pipe 1, its axial position does not change with the unfolding or compression of the filter 2.

[0056] The distal connection portion 26 is axially movable and sleeved on the small-diameter pipe section 11. The inner diameter of the distal connection portion 26 is slightly larger than the outer diameter of the small-diameter pipe section 11, so that the distal connection portion 26 can slide along the small-diameter pipe section 11.

[0057] When the outer pipe 3 moves along the pressing direction to the overlapping area outside the small diameter pipe section 11, an annular radial gap is formed between the outer wall of the small diameter pipe section 11 and the inner wall of the outer pipe 3. This radial gap is continuously distributed along the circumference of the small diameter pipe section 11 and extends along the axial direction of the small diameter pipe section 11.

[0058] After the filter 2 is radially compressed, the proximal support rod 21, the support beam 23, and the distal support rod 22 approach the outer wall of the small-diameter tube segment 11 and are housed in the aforementioned radial gap. The inner wall of the outer tube 3 restricts each support unit from the outside of the filter 2, preventing the filter 2 from unfolding on its own. The small-diameter tube segment 11 continues to maintain the continuity of the central venous access lumen, and the filter 2, housed outside the small-diameter tube segment 11, does not occupy the central venous access lumen.

[0059] The radial thickness of the filter 2 after compression is less than or equal to the radial dimension of the radial gap, allowing the filter 2 to be inserted into the blood vessel as a whole along with the inner tube 1 and the outer tube 3. The axial length of the small-diameter tube segment 11 is not less than the axial length of the filter 2 after full compression, so as to accommodate the compressed proximal support rod 21, support beam 23, distal support rod 22, and distal connection 26 after axial movement.

[0060] Both the proximal connector 25 and the distal connector 26 are cylindrical. The central hole of the proximal connector 25 is used to accommodate the inner tube 1 and is fixedly connected to the large-diameter pipe section 12. The central hole of the distal connector 26 is used to accommodate the small-diameter pipe section 11 and allows the distal connector 26 to slide along the small-diameter pipe section 11.

[0061] At least one of the proximal connecting portion 25 and the distal connecting portion 26 has a retrieval groove 27 on its outer peripheral wall. The retrieval groove 27 can be an annular groove that extends continuously along the entire circumference of the corresponding connecting portion, or it can be an arc-shaped groove that extends partially along the circumference of the connecting portion. When an annular groove is used, the retrieval device can enter the retrieval groove 27 from different circumferential positions; when an arc-shaped groove is used, a gripping position can be formed while maintaining the local wall thickness of the connecting portion.

[0062] In one bidirectional retrieval embodiment, retrieval grooves 27 are provided on the outer peripheral walls of both the proximal connecting portion 25 and the distal connecting portion 26. The retrieval groove 27 provided on the proximal connecting portion 25 is used for grasping retrieval instruments fed in from the proximal side of the filter 2, and the retrieval groove 27 provided on the distal connecting portion 26 is used for grasping retrieval instruments fed in from the distal side of the filter 2, thereby allowing the appropriate retrieval direction to be selected according to the location of the vascular access.

[0063] The bottom and opening of the retrieval tank 27 are both rounded, without forming sharp edges facing the vessel wall. When auxiliary retrieval devices are required, snares, catchers, or other retrieval components can enter the retrieval tank 27 and apply axial tension to the proximal connector 25 or the distal connector 26.

[0064] In this embodiment, the filter 2 is integrally formed from a shape memory alloy, preferably a medical-grade nickel-titanium alloy. During processing, the nickel-titanium alloy tube can be laser-cut to form a proximal connection 25, a proximal support rod 21, a support beam 23, a distal support rod 22, and a distal connection 26. Then, heat setting is used to restore the filter 2 to its fully extended state after the outer tube 3 is released.

[0065] No welded joints are provided between the proximal connecting part 25, the distal connecting part 26 and each support unit to reduce the possibility of detachment or fatigue fracture at the connection point.

[0066] The proximal connector 25, the distal connector 26, and the exposed edges of the support unit all feature smooth transitions. The outer surfaces of the proximal support rod 21, the support beam 23, and the distal support rod 22 that come into contact with the vessel wall have no sharp corners. The edges of the retrieval groove 27, the openings of the dispersion holes 24, and the joints of each rod are also rounded to reduce scratching of the vessel intima during device release, placement, and retrieval.

[0067] The outer tube 3 has a flared opening 31 at its distal end. The flared opening 31 is formed by the outward expansion of the distal part of the outer tube 3, and both its inner and outer surfaces are rounded. The diameter of the distal opening of the flared opening 31 is larger than the inner diameter of the main body of the outer tube 3, so that the proximal support rod 21 can gradually close along the flared opening 31 before entering the outer tube 3.

[0068] Furthermore, the angle φ between the generatrix of the inner surface of the flared opening 31 and the central axis of the outer tube 3 is 30° to 75°, preferably 45° to 60°. If the angle φ is too small, the axial length of the flared opening 31 increases, and the space occupied by the distal end of the outer tube 3 increases; if the angle φ is too large, the local pressure exerted by the inner surface of the flared opening 31 on the proximal support rod 21 increases. The above-mentioned angle range allows the flared opening 31 to gradually compress the proximal support rod 21 within a limited axial length.

[0069] Specifically, let φ be the angle between the generatrix of the inner surface of the bell mouth 31 and the central axis of the outer pipe 3, and let the outer diameter of the small-diameter pipe section 11 be φ. The inner diameter of outer tube 3 is The maximum outer diameter of filter 2 after complete compression is c, the maximum outer diameter of the tip 4 is k, and the maximum outer diameter of the distal end of the bell mouth 31 is [missing information]. The parameters satisfy:

[0070] .

[0071] Preferably, .

[0072] Wherein, the projection of c in the direction perpendicular to the central axis of inner tube 1 is The flared opening 31 provides inlet space for the compressed filter 2 on both sides of the inner tube 1. Therefore, the maximum outer diameter at the distal end of the flared opening 31 is... The outer diameter of the small-diameter pipe section 11 The sum of the radial projections of the two sides into the space is used to determine the result.

[0073] The inner surface of the flare 31 is preferably polished, and the surface roughness is no greater than Ra0.8μm. The distal edge of the flare 31 is rounded to avoid scratching the blood vessel wall during implantation, release or retrieval.

[0074] The distal end of the inner tube 1 is provided with a terminal tip 4, which is fixedly connected to the small-diameter tube segment 11. Its interior can communicate with the central venous access lumen of the inner tube 1, or it can be set as a closed end depending on the purpose of the catheter. The outer surface of the terminal tip 4 gradually expands from the distal end to the proximal end, with a rounded transition and no sharp edges, and is connected to the small-diameter tube segment 11 through the rounded surface, forming a smooth and non-invasive contour.

[0075] After the filter 2 is fully compressed and housed in the outer tube 3, the tip 4 of the filter abuts against the opposite end face of the flared mouth 31. The maximum outer diameter of the distal end of the flared mouth 31 is the same as the maximum outer diameter of the tip 4 of the filter, so that the outer contours are basically continuous when the two abut against each other, reducing the steps formed when the combined structure passes through the blood vessel.

[0076] The distal tip 4 and the flared opening 31 are positioned by end-face contact. When the operator pushes the outer tube 3, and the end face of the flared opening 31 contacts the opposite end face of the distal tip 4, it indicates that the outer tube 3 has moved to the storage position of the filter 2. This contact position also restricts the outer tube 3 from moving further distally, reducing excessive compression of the filter 2.

[0077] The outer tube 3 includes a flexible tube body, which can be made of TPU (thermoplastic polyurethane elastomer) or Pebax (polyetheramide elastomer). The material hardness can be selected according to the diameter of the outer tube 3 and the placement location. In one embodiment, the Shore hardness of the TPU material is 80A to 100A, allowing the outer tube 3 to bend with the blood vessel while maintaining the shape of the lumen.

[0078] A spring support layer 32 is embedded in the wall of the flexible tube. The spring support layer 32 is spirally wound along the axial direction of the outer tube 3 and is located between the inner and outer surfaces of the flexible tube. The spring support layer 32 can be made of stainless steel wire or nickel-titanium wire, and the wire diameter can be from 0.025 mm to 0.10 mm.

[0079] The adjacent spring coils of the spring support layer 32 can be spaced apart or placed close together. The spring coil spacing can be reduced near the flared end 31 to withstand the axial thrust generated when the filter 2 is retracted; the spring coil spacing can be increased in the middle of the outer tube 3 to maintain the bending performance of the outer tube 3.

[0080] The spring support layer 32 preferably terminates at the proximal end of the flared end 31 to prevent the end of the spring wire from being exposed from the flared end 31. The distal end of the spring support layer 32 may be covered with a flexible material to form a closed end.

[0081] When the outer tube 3 bends, the spring-supported layer 32 restricts the cross-section of the flexible tube from flattening. When the outer tube 3 pushes the filter 2 along the pressing direction, the spring-supported layer 32 transmits axial thrust, reducing the occurrence of local collapse or buckling of the outer tube 3 within the curved blood vessel.

[0082] The outer wall of the flexible tube is provided with an anticoagulant coating 33, which may be heparin, polyethylene glycol, choline phosphate, or a composite coating containing the above materials. The thickness of the anticoagulant coating 33 may be 0.5 μm to 5 μm, and it may be bonded to the outer wall of the flexible tube by chemical bonding, grafting after plasma treatment, or as a base coating.

[0083] An anticoagulant coating 33 covers the outer surface of the outer tube 3 that needs to remain inside the blood vessel to reduce the adhesion of blood components to the surface of the outer tube 3. An anticoagulant coating 33 may also be provided on the outer surface of the flared end 31, but the end face of the flared end 31 that directly contacts the terminal tip 4 may not be coated to avoid the coating from falling off due to contact friction.

[0084] Each support beam 23 is connected to the corresponding proximal support rod 21 and distal support rod 22. When the filter 2 is fully deployed, multiple support beams 23 are distributed circumferentially along the inner tube 1 and are in contact with or adjacent to the inner wall of the blood vessel.

[0085] Multiple dispersion holes 24 are provided on the supporting crossbeam 23, each dispersion hole 24 penetrating the supporting crossbeam 23, and the axis of the dispersion hole 24 extends radially along the inner tube 1. Thus, the inner opening of the dispersion hole 24 faces the central axis of the inner tube 1, and the outer opening faces away from the central axis of the inner tube 1.

[0086] The dispersion holes 24 can be distributed at intervals along the length of the support beam 23, and a continuous metal connection section is maintained between adjacent dispersion holes 24. A solid area sufficient to withstand the support load is maintained between the dispersion holes 24 and the edge of the support beam 23.

[0087] The dispersion hole 24 can be a round hole, an oblong hole, or an oblong elliptical hole. When the dispersion hole 24 is an oblong hole, the long axis or length direction of the oblong hole is consistent with the extension direction of the support beam 23. The two ends of the oblong hole are preferably semi-circular or arc-shaped to avoid forming sharp corners at the hole ends.

[0088] The dispersion holes 24 reduce the local cross-sectional area of ​​the support beam 23, enabling the support beam 23 to produce controlled bending during the compression and expansion of the filter 2. Multiple dispersion holes 24 are distributed along the extension direction of the support beam 23, which can reduce abrupt changes in stiffness in the connection area of ​​the proximal support rod 21, the support beam 23, and the distal support rod 22, reducing the continuous pressure and stimulation of the venous intima by the beam edge, and lowering the probability of intimal hyperplasia, vascular perforation, and intimal tearing.

[0089] The dispersion hole 24 also reduces the metal contact area between the support beam 23 and the vascular intima, reduces foreign body stimulation, and inhibits inferior vena cava stenosis caused by excessive intimal proliferation in the long term. When the support beam 23 is close to the vascular wall, blood can flow through the dispersion hole 24, reducing the possibility of forming a closed stagnant area on the beam surface.

[0090] During X-ray or ultrasound observation, the dispersion holes 24 form an alternating outline on the support beam 23, which can improve the imaging effect of the filter 2, identify the position and unfolded shape of the support beam 23, and improve the service life and clinical safety of the device. The number and size of the dispersion holes 24 can be determined according to the length and width of the support beam 23 and the unfolded outer diameter of the filter 2.

[0091] Furthermore, a developing ring 5 is provided on the tip 4 at the end. The developing ring 5 can be made of platinum-iridium alloy, tantalum, gold or other materials that can form a clear image under X-rays.

[0092] An annular mounting groove can be provided on the outer wall of the tip 4, and the developing ring 5 is embedded in the annular mounting groove. The outer diameter of the developing ring 5 is smaller than the maximum outer diameter of the tip 4, so that the developing ring 5 does not protrude beyond the maximum outer contour of the tip 4.

[0093] The imaging ring 5 is located on the side of the tip 4 near the flared opening 31. When the tip 4 abuts against the flared opening 31, the imaging ring 5 is located inside the outer tube 3. The operator observes the position of the imaging ring 5 under the imaging device. When the imaging ring 5 enters the distal end of the outer tube 3 and is located inside the flared opening 31, it can be determined that the filter 2 has entered the outer tube 3.

[0094] In one embodiment, a contrast marker may be provided at the flared opening 31 or the inner wall of the outer tube 3. When the filter 2 is in place, the contrast ring 5 and the contrast marker form a predetermined positional relationship in the axial direction. The surgeon can determine whether the tip 4 has abutted against the flared opening 31 by observing whether the two contrast markers have reached this positional relationship.

[0095] The developing ring 5 and the dispersing hole 24 together form the front positioning mark and the filter 2 shape mark. The developing ring 5 is used to show the position of the far end of the inner tube 1 and the end tip 4, and the dispersing hole 24 is used to show the position of the supporting beam 23, so that the unfolding and retracting state of the filter 2 relative to the end tip 4 can be observed.

[0096] In some embodiments, when the filter 2 is fully extended, the length D of each supporting beam 23 is 1mm-20mm, and the maximum outer diameter B of the filter 2 is 20mm-32mm. Please refer to... Figure 2 The length D of the support beam 23 refers to the length measured along the extension direction of the support beam 23, from the connection point between the support beam 23 and the proximal support rod 21 to the connection point between the support beam 23 and the distal support rod 22. The maximum outer diameter B of the filter 2 refers to the maximum radial dimension of the filter 2, measured perpendicular to the central axis of the inner tube 1, in its fully deployed state without being constrained by the outer tube 3 and the blood vessel wall.

[0097] For filter 2 with a maximum outer diameter adapted to blood vessels with an inner diameter of 20 mm to 25 mm, the ratio of the length of the support beam 23 to the maximum outer diameter of filter 2 is preferably 0.1 to 0.6. This ratio gives the support beam 23 a larger axial length, which, together with the dispersion hole 24, reduces the local stiffness of the beam and reduces the local pressure on small-diameter blood vessels.

[0098] For filter 2 whose maximum outward diameter is adapted to a blood vessel with an inner diameter greater than 25 mm and not greater than 32 mm, the above ratio is preferably 0.1 to 0.5. This ratio improves the ability of the circumferential frame of filter 2 to resist radial compression by shortening the support beam 23.

[0099] Different specifications of filters 2 can adopt different lengths of support beams 23, unfolded outer diameters, support rod widths, and the number of dispersion holes 24.

[0100] During assembly, filter 2 is first placed in the distal region of inner tube 1. Proximal connection 25 is fixed to the distal end of large-diameter tube section 12, and distal connection 26 is sleeved on small-diameter tube section 11 and can slide axially. End tip 4 is fixed to the distal end of small-diameter tube section 11, and developing ring 5 is embedded in end tip 4.

[0101] Then, the outer tube 3 is inserted into the proximal end of the inner tube 1, so that the outer tube 3 covers the large-diameter pipe section 12; the outer tube 3 is pushed to move along the pressing direction, and the flared mouth 31 first contacts the proximal support rod 21. The flared mouth 31 slides along the outer surface of the proximal support rod 21 and presses the proximal support rod 21 toward the inner tube 1.

[0102] After the proximal support rod 21 retracts, the support beam 23 moves toward the inner tube 1, and the distal support rod 22 retracts accordingly. The distal connection part 26 moves toward the distal end along the small diameter pipe section 11, and the filter 2 gradually enters the radial gap between the small diameter pipe section 11 and the outer tube 3.

[0103] Continue pushing the outer tube 3 until the opposite end face of the flared end 31 abuts against the tip 4. At this point, the filter 2 is completely housed inside the outer tube 3, the imaging ring 5 is located inside the outer tube 3, and the central venous catheter is in the delivery state.

[0104] In use, the central venous catheter can be inserted into the target blood vessel via the femoral vein or jugular vein. The spring-supported layer 32 prevents the outer tube 3 from collapsing at bends, and the smooth outer contour of the distal tip 4 guides the catheter through the blood vessel. The operator uses the contrast ring 5 to determine the position of the distal tip 4.

[0105] After reaching the predetermined release position of filter 2, keep inner tube 1 stationary and retract outer tube 3 in the opposite direction of the pressing direction. The flared mouth 31 gradually moves away from the proximal support rod 21, and filter 2 unfolds under the action of the shape memory alloy restoring force. The distal connection part 26 moves towards the proximal end along the small diameter pipe section 11, and the proximal support rod 21, support beam 23 and distal support rod 22 open outwards until filter 2 reaches the fully unfolded state.

[0106] After the filter 2 is deployed, multiple supporting beams 23 are distributed around the inner tube 1 and close to the inner wall of the blood vessel. The proximal support rod 21 and the distal support rod 22 support the beams 23 from both sides of the axis. The filter 2 is used to intercept thrombi that flow with the blood. The lumen of the central venous access of the inner tube 1 remains open, and infusion, blood collection or pressure monitoring can continue.

[0107] When filter 2 needs to be recovered, keep the inner tube 1 in position and push the outer tube 3 along the pressing direction. After the flared mouth 31 contacts the proximal support rod 21, press the proximal support rod 21 towards the inner tube 1. The obtuse angle β between the proximal support rod 21 and the support beam 23, and the obtuse angle γ between the distal support rod 22 and the support beam 23 provide folding space for each support unit.

[0108] The outer tube 3 continues to move, and the supporting beam 23 and the distal support rod 22 enter the outer tube 3. The distal connection 26 moves distally along the small-diameter pipe section 11. The dispersion hole 24 causes the supporting beam 23 to bend continuously during compression, reducing load concentration at the beam connection point.

[0109] When the tip 4 of the filter 2 comes into contact with the opposite end face of the flared end 31, the filter 2 is completely retracted into the outer tube 3. At this time, the imaging ring 5 is located inside the outer tube 3. The operator can determine that the filter 2 has been retracted by observing the position of the imaging ring 5 through imaging. Then the inner tube 1, filter 2 and outer tube 3 can be withdrawn from the blood vessel as a whole.

[0110] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0111] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A central venous catheter, characterized in that, It includes an inner tube (1), an outer tube (3) that is axially movable and sleeved outside the inner tube (1), and a filter (2) disposed at the far end of the inner tube (1). The filter (2) includes a proximal connection part (25) fixedly disposed in the inner tube (1), a distal connection part (26) movable along the axial direction of the inner tube (1), and a plurality of support units distributed circumferentially along the inner tube (1); each support unit includes a proximal support rod (21), a support beam (23), and a distal support rod (22) sequentially connected between the proximal connection part (25) and the distal connection part (26). With the direction from the proximal connector (25) to the distal connector (26) as the pressing direction, when the filter (2) is fully extended, the tangent of the proximal support rod (21) at its connection with the proximal connector (25) toward the support beam (23) forms an acute angle α with the pressing direction; the tangent of the proximal support rod (21) at its connection with the support beam (23) toward the proximal connector (25) forms an obtuse angle β with the extension direction of the support beam (23) toward the distal support rod (22), so that when the outer tube (3) moves along the pressing direction, it presses the proximal support rod (21) toward the inner tube (1) and drives the distal connector (26) to move axially, so as to compress and house the filter (2) inside the outer tube (3).

2. The central venous catheter according to claim 1, characterized in that, When the filter (2) is fully extended, the proximal support rod (21) is curved toward the central axis of the inner tube (1), and the middle part of the proximal support rod (21) is located on the side of the line connecting its two ends close to the central axis.

3. The central venous catheter according to claim 1, characterized in that, When the filter (2) is fully extended, the tangent of the distal support rod (22) at its connection with the distal connection (26) toward the support beam (23) forms an acute angle θ with the direction opposite to the pressing direction; the tangent of the distal support rod (22) at its connection with the support beam (23) toward the distal connection (26) forms an obtuse angle γ with the extension direction of the support beam (23) toward the proximal support rod (21). The acute angle α and the acute angle θ are 20°-60°, and the obtuse angle β and the obtuse angle γ are 95°-150°.

4. The central venous catheter according to claim 1, characterized in that, The inner tube (1) is a variable diameter tube comprising a large-diameter tube segment (12) and a small-diameter tube segment (11) connected to each other, and the inner tube (1) has a through central venous access lumen. The proximal connection (25) is fixed to the distal end of the large-diameter pipe section (12) and adjacent to the small-diameter pipe section (11), and the distal connection (26) is axially movable and sleeved on the small-diameter pipe section (11). In the overlapping area where the outer tube (3) is sleeved outside the small diameter pipe section (11), an annular radial gap is formed between the outer wall of the small diameter pipe section (11) and the inner wall of the outer tube (3), and the filter (2) is radially compressed and housed in the radial gap.

5. The central venous catheter according to claim 1, characterized in that, Both the proximal connection (25) and the distal connection (26) are cylindrical, and at least one of them has a recycling groove (27) on its outer peripheral wall. The recycling groove (27) is an annular groove that extends continuously in the circumferential direction or an arc-shaped groove that extends partially in the circumferential direction. The filter (2) is integrally formed from shape memory alloy. The exposed edges of the proximal connection (25), the distal connection (26), and the parts for contacting the blood vessel wall of the support unit are all smooth transition structures.

6. The central venous catheter according to claim 1, characterized in that, The outer tube (3) has a flared mouth (31) with both inner and outer surfaces having a rounded transition at its far end. The angle φ between the generatrix of the inner surface of the flared mouth (31) and the central axis of the outer tube (3) is 30°-75°. The inner tube (1) has a tip (4) at its far end. When the filter (2) is stored in place, the tip (4) abuts against the opposite end face of the flared mouth (31), and the maximum outer diameter of the far end of the flared mouth (31) is the same as the maximum outer diameter of the tip (4).

7. The central venous catheter according to claim 1, characterized in that, The outer tube (3) includes a flexible tube body, and a spring support layer (32) is embedded in the tube wall of the flexible tube body. The spring support layer (32) is spirally wound along the axial direction of the outer tube (3), and an anti-condensation coating (33) is provided on the outer wall of the flexible tube body.

8. The central venous catheter according to claim 1, characterized in that, The supporting beam (23) is provided with a plurality of dispersion holes (24) penetrating the supporting beam (23), and the axis of the dispersion holes (24) extends radially along the inner tube (1); the dispersion holes (24) are round holes or elongated holes, and when the dispersion holes (24) are elongated holes, their long axis direction or length direction is consistent with the extension direction of the supporting beam (23).

9. The central venous catheter according to claim 6, characterized in that, The outer surface of the tip (4) is rounded and without sharp edges, and a developing ring (5) is embedded therein. The outer diameter of the developing ring (5) is smaller than the maximum outer diameter of the tip (4). When the tip (4) abuts against the flared mouth (31), the developing ring (5) is contained in the outer tube (3).

10. The central venous catheter according to claim 1, characterized in that, When the filter (2) is fully extended, the length of each of the supporting beams (23) is 1mm-20mm, and the maximum outer diameter of the filter (2) is 20mm-32mm.

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