A thrombus filter that is easy to fix and safely remove

Abstract

This invention discloses a thrombus filter that is easy to fix and safely remove, relating to the field of medical device technology. The thrombus filter includes a filter screen made of metal wire and a retrieval hook at its proximal end. After the filter screen is released, both the distal and proximal ends have circumferentially evenly distributed petal-shaped mesh openings, the mesh size of which is smaller than that of the middle section mesh opening, and the mesh openings at both ends are staggered circumferentially. Multiple auxiliary positioning structures are provided at the maximum diameter of the filter screen. These structures include a positioning retaining ring and positioning spikes connected by biodegradable bioadhesive. These provide stable anchoring during initial implantation, and after the bioadhesive degrades, allow the positioning spikes and retaining ring to move relative to each other or separate, achieving minimally invasive removal. This invention balances reliable fixation during initial implantation with operational safety during removal, and also has a more significant thrombus-blocking effect.

Description

Technical Field

[0001] This invention relates to the field of interventional medical device technology, and in particular to a thrombus filter that is implanted in human blood vessels to intercept thrombi and has both excellent fixation performance and safe removal characteristics. Background Technology

[0002] After deep vein thrombosis occurs, a detached thrombus can cause a fatal pulmonary embolism. To prevent such events, a thrombus filter is often implanted in the inferior vena cava to intercept the thrombus.

[0003] Existing filters are mostly made of metal wires woven into a mesh structure, which are fixed by circumferential expansion force after implantation through interventional surgery. However, this technology has the following significant drawbacks: (1) Under the impact of blood flow and vascular pulsation, filters that rely solely on circumferential expansion force are prone to displacement, tilting and other unstable phenomena. (2) Some traditional filters use rigid barbs to enhance anchoring. When they are removed later, the barbs are very easy to tear the vascular endothelium, causing massive bleeding or secondary thrombosis, which forces many filters to be left in place permanently. (3) It is difficult to balance reliable initial fixation with safe late removal of the filter; (4) Due to the mesh structure design, the filter is not effective in blocking thrombi.

[0004] Therefore, there is an urgent need in the field for an innovative thrombus filter design that can achieve a more significant thrombus-blocking effect, provide immediate and reliable anchoring to resist displacement in the early stages of implantation, and detach smoothly from the vessel wall with minimal trauma and risk when removal is finally required. This invention is proposed based on this profound technical background and clinical need. Summary of the Invention

[0005] In view of the aforementioned defects or deficiencies in the prior art, the present invention provides a thrombus filter that is convenient to fix and safely removed. The present invention cleverly resolves the contradiction between stable fixation and safe removal by integrating a special auxiliary positioning structure and mesh structure onto the filter body, and improves the thrombus blocking effect.

[0006] One aspect of the present invention provides a thrombus filter that is easy to fix and safely removed, comprising: a filter screen made of metal wire and a retrieval hook disposed at the proximal end of the filter screen; after the filter screen is released and unfolded, both its distal and proximal ends are provided with a plurality of circumferentially evenly distributed petal-shaped mesh openings, the maximum size of the petal-shaped mesh openings being smaller than the maximum size of the mesh openings in the middle section of the filter screen, and the petal-shaped mesh openings at the distal end and the proximal end being staggered from each other in the circumferential direction; a plurality of auxiliary positioning structures are provided at the maximum diameter of the filter screen.

[0007] Furthermore, the petal-shaped mesh at the distal end of the filter screen is axially aligned with the gap region between two adjacent petal-shaped meshes at the proximal end.

[0008] Furthermore, the adjacent petal-shaped meshes at the distal or proximal ends intersect and overlap each other.

[0009] Furthermore, the auxiliary positioning structure includes a positioning retaining ring and a positioning spike, which are fixedly connected by biodegradable bio-adhesive. The longitudinal section of the positioning retaining ring is T-shaped, with a cylindrical base and a flange perpendicular to the axis of the base. The positioning retaining ring is axially fixed to the metal wire of the filter screen through the cylindrical base. The positioning spike has a pointed portion and an abutting portion. The pointed portion extends obliquely along the blood flow direction, and the abutting portion is an annular elastic element with a notch. The notch is smaller than the diameter of the cylindrical base. The end of the pointed portion is fixed at the middle position of the abutting portion, and the abutting portion elastically hugs the cylindrical base and abuts against the flange. The auxiliary positioning structure is configured such that when the bio-adhesive is completely degraded, circumferential relative movement can occur between the positioning spike and the positioning retaining ring. When the thrombus filter is removed, the positioning spike and the positioning retaining ring can be separated.

[0010] Furthermore, the cylindrical base of the positioning retaining ring is fixed to the metal wire of the filter screen by a non-degradable biocompatible adhesive.

[0011] Furthermore, the plurality of the auxiliary positioning structures are arranged at equal intervals along the circumference of the maximum unfolding diameter of the filter screen.

[0012] Furthermore, the auxiliary positioning structure includes an integrally formed spike portion and a spiral winding portion. The spike portion extends obliquely outward from the surface of the filter screen, and the spiral winding portion is fixed on the metal wire of the filter screen.

[0013] Furthermore, the auxiliary positioning structure includes a spike and a biodegradable fixing part. The spike is fixed to the metal wire of the filter screen by the biodegradable fixing part and extends obliquely outward from the surface of the filter screen. The auxiliary positioning structure is configured to allow the spike to separate from the filter screen when the thrombus filter is removed, and to allow the spike to remain in the blood vessel.

[0014] Furthermore, the angle between the spike and the blood flow direction is 30-60 degrees.

[0015] Furthermore, a development mark is provided on the recycling hook near the filter screen.

[0016] The thrombus filter provided by this invention, which is convenient to fix and safely remove, has the following beneficial effects: (1) Through the auxiliary positioning structure, the thrombus filter can provide immediate and reliable radial support and axial anti-displacement capability in the early stage of implantation, and can also achieve safe separation of the anchoring component from the filter screen through bio-adhesive degradation and structural separation when it is removed, which greatly reduces the risk of damage to the blood vessel wall when the thrombus filter is removed.

[0017] (2) By setting special structured valve-shaped meshes at the distal and proximal ends of the filter, the efficiency and reliability of thrombus interception can be greatly improved. Attached Figure Description

[0018] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of a thrombus filter in a blood vessel, which is convenient to fix and safely removed according to an embodiment of this application; Figure 2 This is a schematic diagram of a filter structure provided in another embodiment of this application. Figure 1 ; Figure 3 This is a schematic diagram of a filter structure provided in another embodiment of this application. Figure 2 ; Figure 4 This is a schematic diagram of a filter structure provided in another embodiment of this application. Figure 3 ; Figure 5 This is a schematic diagram of a filter structure provided in another embodiment of this application. Figure 4 ; Figure 6 This is a schematic diagram of a filter structure provided in another embodiment of this application. Figure 5 .

[0019] Figure 7 This is a schematic diagram of an auxiliary positioning structure provided in another embodiment of this application. Figure 1 ; Figure 8 This is a schematic diagram of an auxiliary positioning structure provided in another embodiment of this application. Figure 2 ; Figure 9 This is a schematic diagram of an auxiliary positioning structure provided in another embodiment of this application. Figure 3 . Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0021] See Figure 1 This embodiment illustrates a basic form of a thrombus filter that is easy to remove. The filter may consist of a generally conical filter mesh 110 woven from biocompatible metal wires (such as nickel-titanium alloy). A retrieval hook 120 is provided at the proximal end (i.e., in the direction of the cone apex, typically cephalic side) of the filter mesh 110 for retrieval by interventional instruments when needed; the retrieval hook 120 is typically provided with a contrast marker. Multiple auxiliary positioning structures 130 are circumferentially arranged at the maximum diameter of the filter mesh 110, which are used to anchor the filter mesh 110 to the vessel wall 140.

[0022] To improve the filter's ability to block blood clots, the present invention improves the mesh structure of the filter screen 110, which will be more clearly explained through the following embodiments.

[0023] Example 1 See Figure 2 This embodiment features a staggered arrangement of petal-shaped mesh openings at both ends. In this embodiment, when the filter 110 is released and unfolded, both its distal and proximal ends are provided with multiple circumferentially evenly distributed petal-shaped mesh openings 1101 in equal or unequal numbers. The petal-shaped mesh openings 1101 are in various petal shapes, preferably a shape with two or more arcs connected end to end. The maximum size of the petal-shaped mesh openings 1101 is smaller than the maximum size of the mesh openings in the middle section of the filter 110, with the maximum size of the petal-shaped mesh openings controlled between 1.0 mm and 3.0 mm. The maximum size of the mesh openings in the main body of the middle section of the filter is between 3.0 mm and 5.0 mm, to enhance local interception capability.

[0024] More preferably, the distal and proximal valve-shaped meshes 1101 are staggered in the circumferential direction, meaning that from the axial view of the filter 110, the gaps between the distal valve-shaped meshes 1101 and the two adjacent proximal valve-shaped meshes 1101 are directly opposite each other. This circumferentially staggered layout creates an interlaced multi-layered filtration surface in the axial direction, significantly increasing the effective filtration area and thrombus interception path within a limited implantation length, thereby improving filtration efficiency and reliability.

[0025] More preferably, the adjacent petal-shaped meshes 1101 at the distal or proximal end overlap each other, which greatly increases the interception area of ​​the petal-shaped meshes 1101 at the distal or proximal end and prevents the micro-emboli from leaking out from the gaps between the adjacent petal-shaped meshes 1101.

[0026] This embodiment is a preferred implementation of the present invention. By using a layout design in which the distal and proximal petal-shaped mesh openings are circumferentially staggered and allow for cross-overlap, an interlaced multi-layered filtration network is constructed within a limited axial space. This not only significantly increases the effective interception area and thrombus capture path, but also achieves graded interception of thrombi of different sizes, greatly improving the reliability and safety of filtration.

[0027] Example 2 See Figure 3-4 In this embodiment, the filter screen 110 has a distal petal-shaped mesh and a proximal straight spoke guide structure. In this embodiment, after the filter screen 110 is released and unfolded, its distal end (i.e., the end furthest from the retrieval hook or the operator) is formed into a plurality of circumferentially uniformly distributed petal-shaped meshes 1101. Figure 3 It is a lobed cross, Figure 4 (For independent valve-shaped meshes). These valve-shaped meshes 1101 are woven from metal wires, with the maximum size of the valve-shaped meshes controlled between 1.0 mm and 3.0 mm. The maximum mesh size in the main body of the middle section of the filter is 3.0 mm to 5.0 mm. This design makes the distal meshes finer, effectively intercepting smaller thrombus particles and improving filtration safety. Meanwhile, the proximal end of the filter 110 (i.e., the end near the retrieval hook or the operator) does not have valve-shaped meshes, but instead consists of a radial straight spoke structure made of several metal wires. These metal wires extend radially outward from near the base of the retrieval hook 120, without intersecting each other, forming an open umbrella-shaped guide. This structure allows for smooth, interference-free convergence towards the central axis during retrieval, significantly reducing retrieval resistance and operational risks.

[0028] Example 3 See Figure 5 This embodiment features a circumferentially aligned structure with petal-shaped mesh openings at both ends. In this embodiment, the filter screen 110 has multiple circumferentially evenly distributed petal-shaped mesh openings 1101 at both its distal and proximal ends. Figure 5To ensure the petal-shaped mesh openings do not cross (the case of overlapping petal-shaped mesh openings is not shown), and the size of the petal-shaped mesh openings 1101 is smaller than the size of the mesh openings in the middle section of the filter screen 110, the maximum size of the petal-shaped mesh openings 1101 is controlled between 1.0 mm and 3.0 mm, and the maximum size of the mesh openings in the main body of the middle section of the filter screen is 3.0 mm to 5.0 mm to enhance local interception capability. In this embodiment, the distal petal-shaped mesh openings 1101 and the proximal petal-shaped mesh openings 1101 are designed to overlap circumferentially, that is, from the axial perspective of the filter screen 110, the proximal petal-shaped mesh openings exactly overlap with the distal petal-shaped mesh openings. This symmetrical layout with circumferential overlap allows the filter screen 110 to provide uniform and symmetrical circumferential support after release, which is beneficial for rapid and stable adhesion to the wall, and the structure is regular with good manufacturing process consistency, while also enhancing the thrombus interception effect.

[0029] Example 4 See Figure 6 In this embodiment, the guide structure has straight spokes at both ends. Alternatively, a radial straight spoke structure composed of several metal wires can be used at both the distal and proximal ends of the filter 110, instead of a petal-shaped mesh. The metal wires at both ends extend radially outward from near the base of the retrieval hook 120 or the distal base, without intersecting, forming an open umbrella-shaped guide opening. This structure allows for smoother and more interference-free convergence towards the central axis during release and retrieval, significantly reducing retrieval resistance and operational risks. Simultaneously, the radial straight spoke structure composed of densely arranged multiple metal wires at the distal and proximal ends can effectively block thrombi.

[0030] The filter screen 110 can be woven from highly elastic metal wires such as nickel-titanium alloy. The petal-shaped mesh 1101 can be achieved by locally adjusting the weaving pattern during the weaving process, or through post-processing shaping (such as expansion shaping after laser cutting of the pipe). The petal-shaped mesh 1101 is an approximate petal shape formed by two or more arcs joined end-to-end. This invention does not impose specific limitations on the petal shape, as long as it achieves the purpose of blocking blood clots. Differences in mesh size can be achieved by using finer metal wires locally, or by adjusting the weaving density.

[0031] Those skilled in the art will understand that the filter structure of the above embodiments can be selected or combined according to different clinical scenarios, such as blood vessel diameter, thrombus burden, and expected implantation time. Its core lies in improving the interception performance of detached thrombi by locally refining the mesh, and through the special design of the proximal structure, such as straight spokes, staggered valve shapes, or overlapping valve shapes, to synergistically optimize filtration efficiency, structural stability, and ease of recycling, thereby better achieving the core objective of the present invention as a whole.

[0032] In order to enable the thrombus filter to provide immediate and reliable radial support and axial anti-displacement capability in the early stage of implantation, and to be easily removed without damaging the blood vessel wall, this application has designed several auxiliary positioning structures for the thrombus filter. These auxiliary positioning structures are different from the barbs or barbs fixed to the filter screen in the prior art, and can achieve reversible anchoring of the filter.

[0033] Example 5 See Figure 7In this embodiment, the auxiliary positioning structure 130 is a detachable retaining ring-anchoring spike structure. The auxiliary positioning structure 130 includes a positioning retaining ring 131 and a positioning spike 132. The longitudinal cross-section of the positioning retaining ring 131 is T-shaped, with a cylindrical base 131a and a disc-shaped flange 131b perpendicular to the axis of the base 131a. The positioning retaining ring 131 is fitted and fixed (e.g., by laser welding or bonding) to a metal wire of the filter screen 110 through its base 131a. The flange 131b serves to support and limit movement. The positioning spike 132 has a spike portion 132a and an abutment portion 132b. The spike portion 132a extends obliquely outward from the surface of the filter screen 110 (the direction of extension is consistent with the direction of blood flow), and its end is designed as a sharp point to facilitate penetration into the blood vessel wall. The abutment portion 132b is an annular elastic element (or C-shaped elastic element) with a notch, and the notch is smaller than the diameter of the cylindrical base 131a. The end of the spike 132a is fixed in the middle position of the abutment portion 132b. The positioning spike 132 is elastically engaged with the cylindrical base 131a of the positioning retaining ring 131 by the abutment portion 132b, and the end face of the abutment portion 132b abuts against the flange 131b of the positioning retaining ring 131. This connection method allows the positioning spike 132 to be restricted radially, but allows for a certain degree of movement in the circumferential direction. The gap between the base 131a of the positioning retaining ring 131 and the abutment portion 132b of the positioning spike 132, or around both, is filled with biodegradable bio-adhesive. The biodegradable bioadhesive is initially cured upon implantation, firmly bonding the positioning needle 132 to the positioning retainer ring 131, ensuring that the anchoring force is effectively transferred from the stent body to the positioning needle 132, thereby penetrating the vessel wall to provide strong initial anchoring. After several weeks to months, the biodegradable bioadhesive has largely degraded in the blood environment. At this point, the adhesive force between the positioning needle 132 and the positioning retainer ring 131 disappears, and it is only suspended from the base 131a by the abutment portion 132b, forming a semi-movable connection. When the stent needs to be removed at the end of treatment, the physician pulls the thrombus filter using the retrieval hook 120. The axial tension on the positioning needle 132 causes its abutment portion 132b to slide or rotate relative to the base 131a of the retainer ring, thereby tilting the needle portion 132a from its original insertion direction and removing it from the vessel wall tissue in a slipping manner rather than a forced pull. This greatly reduces the risk of tissue tearing and bleeding. In extreme cases, if a positioning needle 132 is slightly tightly wrapped by tissue, the movable connection allows the positioning needle 132 to completely separate from the retaining ring 131 when the filter is removed, thus safely leaving the positioning needle 132 in the blood vessel. Since the positioning needle 132 is typically made of thin, biocompatible metal wire (such as nickel-titanium alloy wire), it ultimately integrates with the blood vessel wall cells and other biological tissues (similar to the principle of permanent stent placement), further ensuring the safety of stent removal procedures.

[0034] This embodiment is a preferred implementation of the present invention, which adopts a detachable retaining ring-anchoring spur structure. In the initial stage of filter implantation, the anchoring spur is rigidly bonded to the retaining ring using biodegradable bio-adhesive, ensuring reliable transmission of anchoring force and providing excellent anti-displacement stability. After the bio-adhesive degrades in vivo according to a predetermined cycle, the anchoring spur transforms into a semi-mobile state that is attached to the retaining ring by an elastic element. At this time, under the action of removal force, the anchoring spur can be gently withdrawn from the blood vessel wall by slippage or active separation, avoiding the risk of tissue tearing and bleeding. This achieves a safe transition from rigid fixation to flexible removal, significantly improving the clinical safety and operability of the product.

[0035] Example 6 See Figure 8 In this embodiment, the auxiliary positioning structure 130 is a spiral winding fixing structure. The auxiliary positioning structure 130 is integrally molded and includes a spike portion 133 and a spiral winding portion 134. The spike portion 133 extends obliquely outward from the surface of the filter screen 110 (extending in the direction of blood flow). The spiral winding portion 134 is tightly wound around the metal wire of the filter screen 110 like a spring, thereby achieving fixation. More preferably, the spiral winding portion 134 is movably connected to the metal wire of the filter screen 110. When the thrombus filter undergoes slight shape changes due to blood flow, the movably connected spiral winding portion 134 allows the spike portion 133, which is integral with it, to slide or rotate slightly relative to the metal wire of the filter screen 110. This avoids rigidly transmitting the stress generated by local deformation to the spike portion 133 that has pierced the blood vessel wall, thereby preventing the spike portion 133 from fatigue fracture due to repeated bending and reducing the risk of continuous prying or cutting damage to the blood vessel wall tissue caused by the spike portion 133. When the filter is removed, the helical winding portion 134 of the movable connection can slide or rotate relative to the axial traction force applied by the physician. This allows the spike portion 133 to more easily transition from an insertion position to a smooth withdrawal position, significantly reducing the likelihood of hooking and tearing the blood vessel wall tissue. Compared to fixation methods that require precision welding or bonding, this winding and movable connection method is simpler to manufacture, lower in cost, and reduces reliance on heat-affected zones or adhesive biocompatibility, thereby improving the overall reliability and consistency of the product.

[0036] Example 7 See Figure 9In this embodiment, the auxiliary positioning structure 130 is a biodegradable adhesive fixation structure. The auxiliary positioning structure 130 includes a spike portion 135a and a biodegradable fixation portion 135. The root of the spike portion 135a is bonded and fixed to the metal wire of the filter screen 110 via the biodegradable fixation portion 135. The material of the biodegradable fixation portion 135 is preferably polylactic acid, polycaprolactone, etc. In the initial stage of thrombus filter implantation, the solidified biodegradable fixation portion 135 firmly fixes the spike portion 135a to the filter screen 110, providing anchoring force to the blood vessel wall. When removal is required, the biodegradable fixation portion 135 has completely or partially degraded, and the connection strength between the spike portion 135a and the filter screen 110 is greatly weakened or disappears. The spike portion 135a easily separates from the filter screen 110 and remains in the blood vessel. The spike portion 135a remaining in the body is gradually encapsulated by fibrous tissue, becoming a harmless foreign body.

[0037] The technical solutions of embodiments 5-7 above can be combined with the technical solutions of embodiments 1-4 to form new technical solutions. The new technical solutions can simultaneously achieve significant thrombus blocking effects, as well as low trauma risk during initial implantation and removal.

[0038] The above description is merely a preferred embodiment of the present invention. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to the specific combination of the above-described technical features, but should also cover other technical solutions formed by any combination of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A thrombus filter that is easy to fix and safe to retrieve, characterized in that, include: A filter screen made of metal wire and a collection hook disposed near the proximal end of the filter screen; After the filter is released and unfolded, it has multiple circumferentially evenly distributed petal-shaped mesh holes at both its distal and proximal ends. The maximum size of the petal-shaped mesh holes is smaller than the maximum size of the mesh holes in the middle section of the filter. The petal-shaped mesh holes at the distal and proximal ends are staggered in the circumferential direction. Multiple auxiliary positioning structures are provided at the maximum diameter of the filter.

2. The filter of claim 1, wherein, The petal-shaped mesh at the far end of the filter screen is axially aligned with the gap region between two adjacent petal-shaped meshes at the near end.

3. The filter of claim 1, wherein, The adjacent petal-shaped meshes at the distal or proximal ends intersect and overlap with each other.

4. A thrombus filter that is easy to fix and safely removed according to claim 1, characterized in that: The auxiliary positioning structure includes a positioning retaining ring and a positioning spike, which are fixedly connected by biodegradable bio-adhesive. The positioning retaining ring has a T-shaped longitudinal section and a cylindrical base and a flange perpendicular to the axis of the base; the positioning retaining ring is axially fixed to the metal wire of the filter screen through the cylindrical base; The positioning needle has a pointed part and a supporting part. The pointed part extends obliquely along the blood flow direction. The supporting part is an annular elastic element with a notch. The notch is smaller than the diameter of the cylindrical base. The end of the pointed part is fixed at the middle position of the supporting part. The supporting part elastically hugs the cylindrical base and abuts against the flange. The auxiliary positioning structure is configured such that when the bio-adhesive is completely degraded, circumferential relative movement can occur between the positioning spike and the positioning retaining ring; when the thrombus filter is removed, the positioning spike and the positioning retaining ring can be separated.

5. The filter of claim 4, wherein, The cylindrical base of the positioning retaining ring is fixed to the metal wire of the filter screen by a non-degradable biocompatible adhesive.

6. The filter of claim 4, wherein: The auxiliary positioning structures are arranged at equal intervals along the circumference of the maximum unfolding diameter of the filter screen.

7. A thrombus filter that is easy to fix and safely removed according to claim 1, characterized in that: The auxiliary positioning structure includes an integrally formed spike and a spiral winding portion. The spike extends obliquely outward from the surface of the filter screen, and the spiral winding portion is fixed on the metal wire of the filter screen.

8. A thrombus filter that is easy to fix and safely removed according to claim 1, characterized in that: The auxiliary positioning structure includes a spike and a biodegradable fixing part. The spike is fixed to the metal wire of the filter screen by the biodegradable fixing part and extends obliquely outward from the surface of the filter screen. The auxiliary positioning structure is configured to allow the spike to separate from the filter screen when the thrombus filter is removed, and to allow the spike to remain in the blood vessel.

9. The filter of any of claims 4-8, wherein the filter is configured to be deployed in a manner that allows the filter to be easily removed from the patient's body. The angle between the spike and the direction of blood flow is 30-60 degrees.

10. The filter of claim 1, wherein, The filter screen has a recovery hook near the end with a development mark.

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