Segmented vena cava filter system

Abstract

The application provides a sectional vena cava filter system, which comprises a filter and a conveying part, wherein the filter comprises a recovery hook, a filter body and a retention hook; the recovery hook is connected with the filter body, and the retention hook is detachably connected with the filter, so that when the recovery hook is driven by external recovery force to recover the filter body, the retention hook is separated from the filter body and remains in the blood vessel; the conveying part is detachably connected with the filter, and the conveying part has a conveying channel for conveying the filter into the blood vessel. The application solves the problems of the vena cava filter in the prior art, i.e., the filter is not easy to be taken out after being implanted into the blood vessel due to endothelialization, and the blood vessel is damaged when the hook is taken out.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically, to a segmented vena cava filter system. Background Technology

[0002] Pulmonary embolism, a common acute and critical illness in clinical practice, has an increasing incidence rate year by year. It is mainly caused by deep vein thrombosis in the lower extremities detaching and obstructing the pulmonary artery, and in severe cases, it can lead to right heart failure or even sudden death. In order to effectively intercept detached thrombi and reduce the risk of pulmonary embolism and its recurrence, segmented vena cava filter systems, as a minimally invasive interventional device, are widely used in clinical practice.

[0003] In existing technologies, segmented vena cava filter systems are placed in the inferior vena cava and utilize their unique mesh structure to intercept thrombi with a diameter of 3-5 mm. This ensures normal venous blood return while also blocking the path of thrombi into the pulmonary circulation to a certain extent, essentially creating a physical "safety filter" for the cardiopulmonary system. Although segmented vena cava filter systems are highly effective in preventing pulmonary embolism, they are usually implanted long-term or permanently. With prolonged implantation, the segmented vena cava filter system, as a foreign body, continuously stimulates the endothelial cells of the inferior vena cava, leading to gradual proliferation of endothelial tissue that covers the surface of the filter, forming a phenomenon known as "endothelialization."

[0004] As endothelialization deepens, segmented vena cava filter systems, especially their fixation hooks, can adhere tightly to the vessel wall, making subsequent removal extremely difficult. This is particularly true after 3 to 6 months of implantation, when the risk of endothelialization increases significantly, and forced removal can easily cause serious complications such as vessel wall damage, tearing, or even perforation. Furthermore, displacement or tilting of the segmented vena cava filter system within the vessel can further irritate the vessel wall and accelerate the adhesion process. Long-term indwelling segmented vena cava filter systems also face multiple potential risks, including displacement, breakage, secondary thrombosis, and inferior vena cava injury. Summary of the Invention

[0005] The main objective of this invention is to provide a segmented vena cava filter system to solve the problems of existing vena cava filters being difficult to remove after implantation due to endothelialization, and causing vascular damage when removing the hooks.

[0006] To achieve the above objectives, the present invention provides a segmented vena cava filter system, comprising a filter and a delivery unit. The filter includes a retrieval hook, a filter body, and a retention hook. The retrieval hook is connected to the filter body, and the retention hook is detachably connected to the filter so that when the retrieval hook is subjected to an external retrieval force to drive the filter body for filter retrieval, the retention hook separates from the filter body and remains in the blood vessel. The delivery unit is detachably connected to the filter and has a delivery channel for delivering the filter into the blood vessel.

[0007] In one exemplary embodiment, the retention hook engages with the filter body to release the engagement when the filter body is indirectly subjected to an external retraction force; or, the connection between the retention hook and the filter body has at least one stress concentration area, which can break when the filter body is indirectly subjected to an external retraction force, thereby separating the retention hook from the filter body; or, the retention hook and the filter body are connected by a biodegradable component, which degrades and disappears after the filter is implanted in a blood vessel, thereby separating the retention hook from the filter body.

[0008] In an exemplary embodiment, the retention hook engages with the filter body. The retention hook includes an assembly and a first hook body. The assembly has two limiting holes, and the first hook body is connected to the assembly. The filter body has two limiting legs, each corresponding to one of the two limiting holes. The two limiting legs have a first preset angle A in their normal state. Both limiting legs can elastically deform so that when they pass through the two limiting holes, an external force causes both limiting legs to deform parallel to the axial direction of the two limiting holes. After the two limiting legs pass through their respective limiting holes, they return to the state of the first preset angle to prevent the retention hook from dislodging along the first direction before the filter is implanted into a blood vessel.

[0009] In an exemplary embodiment, the limiting leg includes an assembly section and a limiting section connected together. The extension direction of the assembly section is parallel to the axial direction of the limiting hole. The assembly section is used to mate with the limiting hole. The limiting section can elastically deform relative to the assembly section. There is a first preset included angle A between the two limiting sections. The filter body also includes a stop block. The stop block is connected to the end of the assembly section away from the limiting section. At least a portion of the outer contour of the stop block protrudes from the outer contour of the assembly section to form a stop surface for the retention hook to move in a second direction opposite to the first direction.

[0010] In an exemplary embodiment, the range of the first preset included angle A is: 60°≤A≤70°.

[0011] In one exemplary embodiment, the retention hook engages with the filter body, wherein the filter body has a first limiting groove and the retention hook has a first limiting protrusion, the first limiting protrusion engaging with the first limiting groove; or, the filter body has a second limiting protrusion and the retention hook has a second limiting groove, the second limiting groove engaging with the second limiting protrusion.

[0012] In an exemplary embodiment, the retrieval hook includes a connected assembly column and a second hook body. The filter body includes a support group, a disengagement group, and an anti-displacement group. The support group includes multiple support arms, which are spaced apart and wound around the end of the assembly column away from the second hook body. The multiple support arms are used to closely fit the blood vessel wall to provide radial support force. The disengagement group includes multiple disengagement arms, which are spaced apart and wound around the end of the assembly column away from the second hook body. The end of the disengagement arm away from the assembly column is detachably connected to the retention hook. The anti-displacement group includes multiple limiting arms, which are spaced apart and wound around the end of the assembly column away from the second hook body. The multiple limiting arms are used to abut against the blood vessel wall to prevent the filter from displacing and to keep the filter in a centered state within the blood vessel. The multiple support arms, multiple disengagement arms, and multiple limiting arms are sequentially staggered around the circumference of the assembly column.

[0013] In an exemplary embodiment, the first length L1 of the support arm, the second length L2 of the release arm, and the third length L3 of the limiting arm satisfy the following condition: L1 < L2 < L3.

[0014] In an exemplary embodiment, the first width K1 of the support arm is within the range of 0.25mm ≤ K1 ≤ 0.30mm; and / or, the support arm includes a first support segment, a second support segment, and a third support segment connected in sequence along the direction away from the assembly column. The first and second support segments both extend outward in a trumpet shape, and the third support segment is recessed towards the axial side of the assembly column to prevent scratching the blood vessel wall; wherein, the connection between the first support segment and the second support segment has a second preset angle B, and the value of the second preset angle B is within the range of 115° ≤ B ≤ 130°.

[0015] In an exemplary embodiment, the second width K2 of the release arm is in the range of 0.45mm ≤ K2 ≤ 0.52mm; and / or the opening angle C of the retention hook relative to the release arm is in the range of 115° ≤ C ≤ 120°.

[0016] In an exemplary embodiment, the limiting arm includes a limiting arm body and a bifurcated structure, the bifurcated structure being located at the end of the limiting arm body away from the assembly post; a first bifurcated segment of the bifurcated structure extends along the direction of the limiting arm, and a second bifurcated segment of the bifurcated structure is elastically deformable relative to the first bifurcated segment, the length of the second bifurcated segment being greater than the length of the first bifurcated segment, so that the end of the second bifurcated segment away from the assembly post protrudes beyond the end of the first bifurcated segment away from the assembly post; the second bifurcated segment is used to abut against the blood vessel wall to prevent the filter from shifting and to keep the filter in a centered state within the blood vessel.

[0017] In an exemplary embodiment, the bending radius R of the arc surface of the second hook body is within the range of 1.5mm≤R≤2mm.

[0018] In one exemplary embodiment, the recycling hook is welded to the filter body.

[0019] In one exemplary embodiment, the outer peripheral surface of the filter body has a first coating layer, which is used to reduce the degree of endothelialization after long-term implantation of the filter in blood vessels, thereby reducing the retraction force of the filter.

[0020] In one exemplary embodiment, the peripheral surface of the retained hook has a second coating layer for enabling the retained hook to be rapidly endothelialized in the blood vessel while simultaneously inhibiting excessive cell proliferation and preventing thrombosis.

[0021] In an exemplary embodiment, the delivery channel includes a first delivery channel and a second delivery channel, and the delivery unit includes a delivery sheath and an ejection mechanism, wherein the delivery sheath has a first delivery channel; the ejection mechanism is connected to the delivery sheath and has an ejection end and a second delivery channel; wherein the second delivery channel communicates with the first delivery channel, and the ejection end is slidably disposed within the second delivery channel for ejecting a filter located within the second delivery channel to the first delivery channel, and then delivering it to the blood vessel through the first delivery channel.

[0022] In one exemplary embodiment, the delivery sheath is detachably connected to the ejection mechanism.

[0023] In one exemplary embodiment, the conveying unit further includes a power source connected to the first conveying channel for providing conveying power to the filter located within the first conveying channel.

[0024] In one exemplary embodiment, the outer surface of the delivery sheath has a third coating layer, which is a hydrophilic coating.

[0025] In an exemplary embodiment, the ejection mechanism includes a pre-assembly tube and an ejection tube, wherein the pre-assembly tube has a second conveying channel; the ejection tube includes a tube body and gripping handles and limiting members located at both axial ends of the tube body, with one end of the tube body connected to the limiting member passing through the second conveying channel; wherein the limiting member includes an assembly tube and a limiting structure located on the outer circumferential surface of the assembly tube, the limiting structure having a limiting channel, and there are multiple limiting structures, which are arranged circumferentially around the assembly tube at intervals, with a limiting groove formed between two adjacent limiting structures; the number of limiting channels corresponds one-to-one with the number of release arms, and the limiting channels are used for the release arms to pass through, so as to limit the release arms to retract inward; the number of limiting grooves corresponds one-to-one with the number of limiting arms, and the limiting grooves are used for the limiting arms to engage, so as to limit the limiting arms to retract inward.

[0026] By applying the technical solution of this invention, an innovative separation mechanism for the filter during implantation and retrieval is achieved through a cooperative structure between the filter and the delivery unit. Specifically, the filter includes a retrieval hook, a filter body, and a retention hook, wherein the retention hook and the filter body are designed to be detachably connected. When the doctor applies a retrieval force through the retrieval hook to move the filter body upward, the retention hook can automatically detach from the filter body and remain inside the blood vessel, while only the filter body is retrieved. This effectively solves the problems of traditional vena cava filters, such as severe endothelialization, difficult removal, and easy damage to blood vessels due to long-term implantation. Because the retention hook is in constant contact with the blood vessel wall, it can quickly undergo endothelialization and fuse with the blood vessel, eliminating the need for forced removal and avoiding serious complications such as blood vessel wall tearing, perforation, or massive bleeding caused by violent retrieval. At the same time, the delivery unit has a delivery channel that ensures that the filter can be safely and accurately delivered to the target blood vessel location, guaranteeing the safety and success rate of the surgery. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 A schematic diagram of a segmented vena cava filter system according to an optional embodiment of the present invention is shown;

[0029] Figure 2 It shows Figure 1 A schematic diagram of the ejection mechanism of the segmented vena cava filter system;

[0030] Figure 3 It shows Figure 2 A schematic diagram of the limiting component of the ejection mechanism;

[0031] Figure 4 It shows Figure 2 A schematic diagram of the ejector tube of the ejector mechanism in the middle;

[0032] Figure 5 It shows Figure 1 A schematic diagram of the ejection mechanism of the segmented vena cava filter system, in which the filter is ejected layer by layer. The delivery sheath is omitted in the diagram.

[0033] Figure 6 It shows Figure 5 A schematic diagram of the ejector mechanism continuing to eject the filter;

[0034] Figure 7 A schematic diagram of the filter according to Embodiment 1 of the present invention is shown;

[0035] Figure 8 It shows Figure 7 A magnified structural diagram at point D in the diagram;

[0036] Figure 9 It shows Figure 7 A magnified structural diagram at point E in the diagram;

[0037] Figure 10 It shows Figure 7 The diagram shows the structure of a filter with the retention hook omitted.

[0038] Figure 11 It shows Figure 10 A magnified structural diagram at point F in the diagram;

[0039] Figure 12 It shows Figure 10 A schematic diagram of the structure of the retention hook in the middle;

[0040] Figure 13 A schematic diagram of the filter according to Embodiment 2 of the present invention is shown;

[0041] Figure 14 It shows Figure 13 A magnified structural diagram at point G in the diagram;

[0042] Figure 15 It shows Figure 13 The diagram shows the structure of a filter with the retention hook omitted.

[0043] Figure 16 It shows Figure 15 A magnified structural diagram at point H in the diagram;

[0044] Figure 17 It shows Figure 15 A schematic diagram of the structure of the retention hook in the middle;

[0045] Figure 18 A schematic diagram of the filter according to Embodiment 3 of the present invention is shown;

[0046] Figure 19 It shows Figure 18 A magnified structural diagram at point J in the diagram;

[0047] Figure 20 It shows Figure 18 The diagram shows the structure of a filter with the retention hook omitted.

[0048] Figure 21 It shows Figure 20 A magnified structural diagram at point K in the diagram;

[0049] Figure 22 It shows Figure 20 A schematic diagram of the structure of the retention hook in the middle;

[0050] Figure 23 A schematic diagram of the filter according to Embodiment 4 of the present invention is shown;

[0051] Figure 24 It shows Figure 23 A magnified structural diagram at point M in the diagram;

[0052] Figure 25 It shows Figure 23 Schematic diagrams of filters from different perspectives;

[0053] Figure 26 It shows Figure 25 A magnified structural diagram at point N in the diagram;

[0054] Figure 27 A schematic diagram of the filter according to Embodiment 5 of the present invention is shown;

[0055] Figure 28 It shows Figure 27 A magnified structural diagram at point V in the diagram;

[0056] Figure 29 It shows Figure 27 The diagram shows the structure of a filter with the retention hook omitted.

[0057] Figure 30 It shows Figure 29 A magnified structural diagram at point W in the diagram;

[0058] Figure 31 It shows Figure 27 A schematic diagram of the structure of the retention hook in the middle;

[0059] Figure 32 A schematic diagram of the filter according to Embodiment Six of the present invention is shown;

[0060] Figure 33 It shows Figure 32 A magnified structural diagram at point X.

[0061] The above figures include the following reference numerals:

[0062] 10. Filter; 11. Recycling hook; 111. Assembly column; 112. Second hook body; 12. Filter body; 121. Limiting support; 1211. Assembly section; 1212. Limiting section; 122. Stop block; 123. First limiting slot; 124. Second limiting protrusion; 125. Support arm; 1251. First support section; 1252. Second support section; 1253. Third support section; 126. Release arm; 127. Limiting arm; 1271. Limiting arm body; 1272. Bifurcation structure; 1273. First bifurcation section; 1274. Second bifurcation section; 13. Retention hook; 131. Assembly; 1311. Limiting hole; 132. First hook body; 133. First limiting protrusion; 134. Second limiting slot; 14. Stress concentration area; 15. Biodegradable component;

[0063] 20. Conveying section; 21. Conveying sheath; 211. First conveying channel; 22. Ejection mechanism; 221. Second conveying channel; 222. Pre-installed tube; 223. Ejection tube; 2231. Tube body; 2232. Handle; 2233. Limiting component; 2234. Assembly tube; 2235. Limiting structure; 2236. Limiting channel; 2237. Limiting groove; 23. Power source. Detailed Implementation

[0064] 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, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0065] To address the problems of existing vena cava filters being difficult to remove after implantation due to endothelialization, and causing vascular damage during hook removal, this invention provides a segmented vena cava filter system.

[0066] Example 1

[0067] like Figures 1 to 12As shown, the segmented vena cava filter system includes a filter 10 and a delivery unit 20. The filter 10 includes a retrieval hook 11, a filter body 12, and a retention hook 13. The retrieval hook 11 is connected to the filter body 12, and the retention hook 13 is detachably connected to the filter 10. When the retrieval hook 11 is subjected to an external retrieval force to drive the filter body 12 to retrieve the filter 10, the retention hook 13 separates from the filter body 12 and remains in the blood vessel. The delivery unit 20 is detachably connected to the filter 10 and has a delivery channel for delivering the filter 10 into the blood vessel.

[0068] By applying the technical solution of this invention, an innovative separation mechanism for the filter during implantation and retrieval is achieved through the cooperative structure of the filter 10 and the delivery unit 20. Specifically, the filter 10 includes a retrieval hook 11, a filter body 12, and a retention hook 13, wherein the retention hook 13 and the filter body 12 are designed to be detachably connected. When the doctor applies a retrieval force through the retrieval hook 11 to move the filter body 12 upward, the retention hook 13 can automatically detach from the filter body 12 and remain in the blood vessel, while only the filter body 12 is retrieved. This effectively solves the problems of severe endothelialization, difficult removal, and easy damage to blood vessels caused by long-term implantation of traditional vena cava filters. Because the retention hook 13 is in long-term contact with the blood vessel wall, it can quickly endothelialize and fuse with the blood vessel, eliminating the need for forced removal and avoiding serious complications such as blood vessel wall tearing, perforation, or massive bleeding caused by violent retrieval. At the same time, the delivery channel of the delivery unit 20 ensures that the filter 10 can be safely and accurately delivered to the target blood vessel location, guaranteeing the safety and success rate of the surgery.

[0069] It should be noted that in this application, the retention hook 13 engages with the filter body 12 in a snap-fit ​​configuration, so that when the filter body 12 is indirectly subjected to an external retraction force, the snap-fit ​​between the retention hook 13 and the filter body 12 can be released. This further limits the separation method between the retention hook 13 and the filter body 12, greatly improving the adaptability and reliability of the technology. The snap-fit ​​configuration provides a flexible separation strategy: it offers a reliable mechanical locking and releasing mechanism.

[0070] like Figures 7 to 8 , Figures 10 to 12As shown, the retention hook 13 engages with the filter body 12. The retention hook 13 includes an assembly 131 and a first hook body 132. The assembly 131 has two limiting holes 1311, and the first hook body 132 is connected to the assembly 131. The filter body 12 has two limiting legs 121, each corresponding to one of the two limiting holes 1311. The two limiting legs 121 have a first preset included angle A when in their normal state. Both limiting legs 121 can undergo elastic deformation. When the two limiting legs 121 pass through the two limiting holes 1311 respectively, the external force causes both limiting legs 121 to deform parallel to the axial direction of the two limiting holes 1311. After the two limiting legs 121 pass through their respective limiting holes 1311, the two limiting legs 121 return to the state of the first preset included angle to prevent the retention hook 13 from dislodging along the first direction before the filter 10 is implanted into the blood vessel. In this way, the retention hook 13 is accurately positioned and locked during installation and use. The limiting legs 121 have the first preset included angle A in normal state. During assembly, they deform through the limiting holes 1311 by external force and then return to their original shape, forming a firm mechanical interlock, which effectively prevents the retention hook 13 from accidentally falling off before the filter 10 is implanted into the blood vessel. This elastic deformation recovery mechanism utilizes the properties of shape memory materials such as nickel-titanium alloys to ensure the stability of the connection and the feasibility of repeated operations. At the same time, it simplifies the assembly process, reduces the production defect rate, and lays a reliable foundation for subsequent safe separation.

[0071] like Figure 11As shown, the limiting leg 121 includes an assembly section 1211 and a limiting section 1212 connected to each other. The extending direction of the assembly section 1211 is parallel to the axial direction of the limiting hole 1311. The assembly section 1211 is used to cooperate with the limiting hole 1311. The limiting section 1212 can elastically deform relative to the assembly section 1211. The two limiting sections 1212 have a first preset included angle A. The filter body 12 also includes a stop block 122. The stop block 122 is connected to the end of the assembly section 1211 away from the limiting section 1212, and at least a portion of the outer contour of the stop block 122 protrudes from the outer contour of the assembly section 1211 to form a stop surface for the retention hook 13 to move in a second direction opposite to the first direction. In this way, by introducing the structural cooperation between the stop block 122 and the limiting section 1212, the retention hook 13 is effectively restricted in bidirectional movement. The stop surface formed by the stop block 122 can restrict the movement of the retention hook 13 in the second direction, i.e., towards the interior of the filter body or away from the blood vessel wall, preventing it from retracting or misaligning during delivery or release; while the limiting segment 1212 restricts its movement in the first direction to prevent dislodgement. This bidirectional limiting design ensures that the retention hook 13 is stable before implantation. Only when the filter body 12 is subjected to a specific upward retraction force will the limiting leg 121 deform and dislodge, thereby achieving controllability and determinism of the separation action and avoiding filter failure or blood vessel damage caused by misoperation.

[0072] It should be noted that in this application, the first preset included angle A is within the range of 60°≤A≤70°. This ensures that the limiting support leg 121 has sufficient elasticity and insertion space during assembly, while also ensuring sufficient clamping force to fix the retention hook 13 under normal conditions, preventing it from loosening. Simultaneously, this angle range optimizes the force distribution during separation, allowing the limiting support leg 121 to bend and disengage smoothly under the action of the recovery force, without the fit being too loose due to an excessively large angle or the disengagement being difficult due to an excessively small angle. This improves the smoothness and success rate of the separation process, extending the filter's service life and safety.

[0073] like Figure 7 and Figure 10As shown, the retrieval hook 11 includes a connected assembly column 111 and a second hook body 112. The filter body 12 includes a support group, a disengagement group, and an anti-displacement group. The support group includes multiple support arms 125, which are spaced apart and wound around the end of the assembly column 111 away from the second hook body 112. The multiple support arms 125 are used to tightly conform to the blood vessel wall to provide radial support force. The disengagement group includes multiple disengagement arms 126, which are spaced apart and wound around the end of the assembly column 111 away from the second hook body 112. One end of the release arm 126, away from the assembly column 111, is detachably connected to the retention hook 13; the anti-displacement group includes multiple limiting arms 127, which are spaced around the end of the assembly column 111 away from the second hook body 112. The multiple limiting arms 127 are used to abut against the blood vessel wall to prevent the filter 10 from displacing and to keep the filter 10 in a centered position within the blood vessel; wherein, the multiple support arms 125, multiple release arms 126, and multiple limiting arms 127 are sequentially staggered around the circumference of the assembly column 111. Thus, by defining the three-layer structure of the filter body 12—a support group including a support arm 125, a disengagement group including a disengagement arm 126, and an anti-displacement group including a limiting arm 127—and clarifying their spatial layout of being sequentially staggered around the assembly column 111, the support arm 125 provides radial support to conform to the vessel wall; the disengagement arm 126 connects to the retention hook 13 and is responsible for the separation function; and the limiting arm 127 prevents the filter from shifting as a whole and maintains its centered position by abutting against the vessel wall. This layered and staggered design ensures that the functions of each part do not interfere with each other. The support arm 125 ensures the stability of the filter, the disengagement group enables safe retrieval, and the anti-displacement group ensures accurate positioning. The three work together to significantly improve the stability and reliability of the filter in complex vascular environments and reduce the risk of complications caused by filter displacement.

[0074] like Figure 7 and Figure 10 As shown, the first length L1 of the support arm 125, the second length L2 of the release arm 126, and the third length L3 of the limiting arm 127 satisfy the following relationship: L1 < L2 < L3. This stepped length design creates a support gradient from the inside out within the blood vessel: the proximal support arm 125 is shorter, providing basic support; the middle release arm 126 is longer, facilitating cooperation with the retention hook 13 and adapting to the vessel depth; the distal limiting arm 127 is the longest, capable of penetrating deep into the vessel wall or abutting at a more distant point, providing the strongest anti-displacement capability. This length gradient optimizes the adaptability of the filter 10 in conical or variable-diameter vessels, ensuring that the filter 10 remains stably centered under different vessel diameters, preventing filter tilting or slippage due to improper length.

[0075] It should be noted that in this application, the first width K1 of the support arm 125 is within the range of 0.25mm ≤ K1 ≤ 0.30mm; and / or, the support arm 125 includes, in sequence, a first support segment 1251, a second support segment 1252, and a third support segment 1253 connected together along the direction away from the mounting column 111. The first support segment 1251 and the second support segment 1252 both extend outward in a trumpet shape, while the third support segment 1253 is recessed towards the axial side of the mounting column 111 to prevent scratching the blood vessel wall; wherein, the connection between the first support segment 1251 and the second support segment 1252 has a second preset angle B, and the value of the second preset angle B is within the range of 115° ≤ B ≤ 130°. In this way, the width of the support arm 125 is controlled between 0.25-0.30mm, which ensures sufficient strength to support the blood vessel while reducing the impact on blood flow. The trumpet-shaped extended first support segment 1251 and second support segment 1252 increase the contact area with the blood vessel wall and improve stability; the inward-pointing third support segment 1253 avoids mechanical damage to the blood vessel wall from sharp edges. The second preset included angle B, between 115° and 130°, optimizes the bending stress distribution of the support arm 125, giving it better fatigue life during expansion and retraction, reducing the risk of breakage, and ensuring the fit to the blood vessel wall.

[0076] It should be noted that in this application, the second width K2 of the release arm 126 is within the range of 0.45mm ≤ K2 ≤ 0.52mm; and / or, the opening angle C of the retention hook 13 relative to the release arm 126 is within the range of 115° ≤ C ≤ 120°. Thus, the wider design of the release arm 126 provides sufficient structural strength to withstand the tensile force during retrieval without plastic deformation; the opening angle of the retention hook 13 is optimized to effectively pierce the vessel wall after implantation, providing strong anchoring force and preventing displacement of the filter after intercepting a large amount of thrombus. Simultaneously, this angle also ensures that the retention hook 13 can smoothly withdraw from the vessel wall or separate from the main body during retrieval, reducing retrieval resistance and ensuring a balance between connection and release of the filter 10, thereby improving the safety and effectiveness of clinical use.

[0077] like Figure 8 and Figure 9As shown, the limiting arm 127 includes a limiting arm body 1271 and a bifurcated structure 1272. The bifurcated structure 1272 is located at the end of the limiting arm body 1271 away from the mounting post 111. The first bifurcated segment 1273 of the bifurcated structure 1272 extends along the direction of the limiting arm 127. The second bifurcated segment 1274 of the bifurcated structure 1272 can elastically deform relative to the first bifurcated segment 1273. The length of the second bifurcated segment 1274 is greater than the length of the first bifurcated segment 1273, so that the end of the second bifurcated segment 1274 away from the mounting post 111 protrudes beyond the end of the first bifurcated segment 1273 away from the mounting post 111. The second bifurcated segment 1274 is used to abut against the blood vessel wall to prevent the filter 10 from shifting and to keep the filter 10 in a centered state within the blood vessel. Thus, the bifurcation structure 1272 of the limiting arm 127, especially the second bifurcation segment 1274 which is longer than the first bifurcation segment 1273 and protrudes, significantly enhances the filter 10's centering ability and anti-displacement performance within the blood vessel. The second bifurcation segment 1274 can fit more tightly against the vessel wall, providing bidirectional clamping force and preventing the filter from axially sliding or rotating under the impact of blood flow. This bifurcation design also disperses local stress, reducing local pressure damage to the vessel wall and improving biocompatibility. By precisely controlling the length and elastic deformation capacity of the bifurcation segments, the filter is ensured to remain centered throughout long-term implantation, reducing the risk of thrombosis or vascular damage due to positional displacement.

[0078] It should be noted that in this application, the bending radius R of the arc surface of the second hook body 112 is within the range of 1.5mm ≤ R ≤ 2mm. This facilitates compatibility with mainstream filter retrievers on the market. The standard bending radius ensures that the retrieval hook 11 can be firmly grasped by the retrieval instrument, avoiding grasping failure or slippage, and improving the convenience and success rate of surgical operations. At the same time, this arc radius also optimizes the streamlined appearance of the hook, reduces the risk of scratching the blood vessel wall during delivery, improves the safety and smoothness of the delivery system, and provides patients with a more comfortable and safe treatment experience.

[0079] It should be noted that in this application, the recovery hook 11 is welded to the filter body 12. This provides strong connection between the recovery hook 11 and the filter body 12, and the weld point can withstand the enormous tensile force generated during recovery, ensuring that the filter body 12 can be reliably driven without loosening or breaking between the recovery hook 11 and the filter body 12. Compared to threaded connections or interference fits, the welding process is simpler, the connection surface is smoother, stress concentration points are reduced, and the overall structural integrity and durability are improved, ensuring the long-term stability and recovery safety of the filter under complex physiological environments.

[0080] It should be noted that in this application, the outer peripheral surface of the filter body 12 has a first coating layer. This first coating layer is used to reduce the degree of endothelialization after long-term implantation of the filter 10 into the blood vessel, thereby reducing the retrieval force of the filter 10. Thus, the design of the first coating layer, such as a rapamycin or paclitaxel coating, can inhibit the excessive proliferation of vascular smooth muscle cells and endothelial cells, delaying the adhesion process between the filter body and the blood vessel wall. This ensures that even after long-term implantation, the filter body maintains a relatively smooth surface, significantly reducing friction and adhesion during retrieval, making the retrieval operation easier and safer, greatly reducing serious complications such as blood vessel wall tearing and bleeding caused by strong traction, and extending the retrieval window period of the filter.

[0081] Optionally, the first coating layer includes, but is not limited to, rapamycin or paclitaxel.

[0082] It should be noted that in this application, the peripheral surface of the retained hook 13 has a second coating layer. This second coating layer is used to facilitate rapid endothelialization of the retained hook 13 within the blood vessel, while simultaneously inhibiting excessive cell proliferation and preventing thrombus formation. Thus, by coating with an RGD peptide or VEGF heparin composite coating, the retained hook 13 can be rapidly covered by the newly formed intima, fusing with the vessel wall and permanently fixed within the vessel without removal. Simultaneously, this coating also possesses anticoagulant and antiproliferative properties, preventing thrombus formation or excessive proliferation beneath the coating, ensuring the long-term biocompatibility and safety of the retained hook 13 in vivo. This dual action of "promoting endothelialization" and "antithrombotic effect" resolves the contradiction of traditional hooks being prone to thrombosis or difficult to endothelialize, improving the safety of long-term patient placement.

[0083] Optionally, the second coating layer includes, but is not limited to, an arginine-glycine-aspartic acid (RGD) peptide coating or a VEGF heparin composite coating, which can accelerate cell adhesion, enable the hooks to be rapidly endothelialized, and inhibit excessive cell proliferation to prevent thrombosis.

[0084] Optionally, the filter body 12 is made by integrally cutting a nickel-titanium tube and then heat-treating it to shape; the recycling hook 11 is a solid nickel-titanium rod that is machined and cut and welded to the filter body 12; and the retention hook 13 is made by cutting a nickel-titanium rod or a stainless steel rod.

[0085] like Figures 1 to 6As shown, the delivery channel includes a first delivery channel 211 and a second delivery channel 221. The delivery unit 20 includes a delivery sheath 21 and an ejection mechanism 22. The delivery sheath 21 has the first delivery channel 211. The ejection mechanism 22 is connected to the delivery sheath 21 and has an ejection end and a second delivery channel 221. The second delivery channel 221 communicates with the first delivery channel 211. The ejection end is slidably disposed within the second delivery channel 221 to eject the filter 10 located in the second delivery channel 221 to the first delivery channel 211, from where it is delivered into the blood vessel. This achieves the layer-by-layer release function of the filter 10. The ejection mechanism 22 can eject the filter 10 from the second delivery channel 221 to the first delivery channel 211, thereby allowing it to enter the blood vessel. This structure allows doctors to precisely control the release sequence and position of the filter under X-ray fluoroscopy, first releasing the proximal support layer, then the distal anti-displacement layer, and finally the hook layer, ensuring that the filter is stably centered in the blood vessel. This avoids the possibility of filter tilting, displacement, or vascular damage that may occur during overall release, thus improving the accuracy and success rate of implantation.

[0086] It should be noted that in this application, the delivery sheath 21 is detachably connected to the ejection mechanism 22. This improves the flexibility and convenience of surgical procedures. Surgeons can select different sizes of delivery sheath 21 based on the specific condition of the patient's blood vessels and quickly assemble or replace them with the ejection mechanism 22. Furthermore, the detachable structure facilitates cleaning, disinfection, and reuse, reducing the cost of reusable instruments or disposable consumables. It also facilitates the inspection and maintenance of the instrument during delivery, improving the overall reliability and economy of the surgical system.

[0087] like Figure 1 As shown, the delivery unit 20 also includes a power source 23, which is connected to the first delivery channel 211 to provide delivery power for the filter 10 located within the first delivery channel 211. This achieves automated or semi-automated delivery of the filter 10. The power source 23 can provide stable and controllable thrust, avoiding uneven force, vibration, or overload problems that may occur with manual push rods. Especially during long-distance or tortuous blood vessel delivery, the power source 23 ensures that the filter 10 passes smoothly and at a uniform speed through the delivery channel, reducing mechanical stimulation and damage to the blood vessel wall, improving the safety and stability of the delivery process, and reducing surgical difficulty and operational risks.

[0088] It should be noted that in this application, the outer surface of the delivery sheath 21 has a third coating layer, which is a hydrophilic coating. This hydrophilic coating significantly reduces the coefficient of friction between the delivery sheath 21 and the blood vessel wall, making the sheath smoother during insertion into the blood vessel and reducing insertion resistance. This not only improves the comfort of the physician's operation but also reduces complications such as vasospasm, intimal damage, or sheath knotting caused by difficulty in insertion. The advantages of the hydrophilic coating are particularly evident when passing through narrow or tortuous areas such as the iliac artery, ensuring smooth passage and safe implantation of the delivery system.

[0089] like Figures 1 to 4 As shown, the ejection mechanism 22 includes a pre-assembly tube 222 and an ejection tube 223. The pre-assembly tube 222 has a second conveying channel 221. The ejection tube 223 includes a tube body 2231 and gripping handles 2232 and limiting members 2233 located at both axial ends of the tube body 2231. One end of the tube body 2231 connected to the limiting member 2233 passes through the second conveying channel 221. The limiting member 2233 includes an assembly tube 2234 and a limiting structure 2235 located on the outer circumferential surface of the assembly tube 2234. The limiting structure 2235 has a limiting channel 2235. 236. Multiple limiting structures 2235 are arranged circumferentially around the assembly tube 2234, with a limiting groove 2237 formed between two adjacent limiting structures 2235. The number of limiting channels 2236 corresponds one-to-one with the number of release arms 126. The limiting channels 2236 are used for the release arms 126 to pass through, limiting their retraction. The number of limiting grooves 2237 corresponds one-to-one with the number of limiting arms 127. The limiting grooves 2237 are used for the limiting arms 127 to engage, limiting their retraction. In this way, the independent retraction and stable loading of each part of the filter 10 are achieved. During the conveying process, the limiting components 2233 effectively prevent the release arms 126 and limiting arms 127 from entanglement, especially preventing the sharp retention hooks 13 from piercing or excessively rubbing against the wall of the conveying sheath 21, thus avoiding particle generation or sheath damage. This sophisticated layered limiting mechanism ensures the structural integrity and safety of the filter throughout the loading, transporting, and releasing process, and is a key technical feature that guarantees the smooth implantation of the filter.

[0090] Example 2

[0091] It should be noted that the difference between this embodiment and Embodiment 1 is that, as Figures 13 to 17 As shown, the retention hook 13 engages with the filter body 12. The filter body 12 has a second limiting protrusion 124, and the retention hook 13 has a second limiting groove 134, which engages with the second limiting protrusion 124. This engagement of the second limiting groove 134 and the second limiting protrusion 124 simplifies mold design, reduces production costs, and maintains the locking and releasing function of the retention hook 13.

[0092] Example 3

[0093] It should be noted that the difference between this embodiment and Embodiment 1 is that, as Figures 18 to 22 As shown, the retention hook 13 engages with the filter body 12. The filter body 12 has a first limiting groove 123, and the retention hook 13 has a first limiting protrusion 133. The first limiting protrusion 133 engages with the first limiting groove 123. In this way, the engagement of the first limiting protrusion 133 and the first limiting groove 123 simplifies mold design, reduces production costs, and maintains the locking and releasing function of the retention hook 13.

[0094] Example 4

[0095] It should be noted that the difference between this embodiment and Embodiment 1 is that, as Figures 23 to 26 As shown, the connection between the retention hook 13 and the filter body 12 has at least one stress concentration area 14. This stress concentration area 14 can break when the filter body 12 is indirectly subjected to an external recovery force, thus separating the retention hook 13 from the filter body 12. This further defines the separation method between the retention hook 13 and the filter body 12, greatly improving the adaptability and reliability of the technology. By setting the stress concentration area 14, a flexible separation strategy is provided: the design of the stress concentration area 14 allows the filter body 12 to break precisely when subjected to a specific recovery force, achieving rapid separation.

[0096] Example 5

[0097] It should be noted that the difference between this embodiment and Embodiment Two is that, as shown in the following... Figures 27 to 31 As shown, the second limiting protrusion 124 is located on the side of the release arm 126 of the filter body 12, and the retention hook 13 has a second limiting groove 134, which engages with the second limiting protrusion 124. This engagement of the second limiting groove 134 and the second limiting protrusion 124 simplifies mold design, reduces production costs, and maintains the locking and releasing function of the retention hook 13.

[0098] Example 6

[0099] It should be noted that the difference between this embodiment and Embodiment 1 is that, as Figure 32 and 33As shown, the retention hook 13 is connected to the filter body 12 via a biodegradable component 15. After the filter 10 is implanted into the blood vessel, the biodegradable component 15 degrades and disappears, allowing the retention hook 13 to separate from the filter body 12. This further defines the separation method of the retention hook 13 from the filter body 12, greatly improving the adaptability and reliability of the technology. By setting the biodegradable component 15, a flexible separation strategy is provided: the biodegradable component 15 allows the retention hook 13 to naturally degrade and disappear over time after implantation, fundamentally eliminating the risk of foreign body retention.

[0100] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0101] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0102] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0103] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0104] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A segmented vena cava filter system, characterized in that, include: The filter (10) includes a recovery hook (11), a filter body (12), and a retention hook (13). The retrieval hook (11) is connected to the filter body (12), and the retention hook (13) is detachably connected to the filter (10). When the retrieval hook (11) is subjected to an external retrieval force and drives the filter body (12) to retrieve the filter (10), the retention hook (13) separates from the filter body (12) and remains in the blood vessel. The delivery unit (20) is detachably connected to the filter (10) and has a delivery channel for delivering the filter (10) into the blood vessel.

2. The segmented vena cava filter system according to claim 1, characterized in that, The retention hook (13) engages with the filter body (12) to release the engagement when the filter body (12) is indirectly subjected to external retraction force; or, The connection between the retention hook (13) and the filter body (12) has at least one stress concentration area (14), which can break when the filter body (12) is indirectly subjected to an external recovery force, so as to separate the retention hook (13) from the filter body (12); or, The retention hook (13) is connected to the filter body (12) by a biodegradable component (15) so that after the filter (10) is implanted into the blood vessel, the biodegradable component (15) degrades and disappears, thereby separating the retention hook (13) from the filter body (12).

3. The segmented vena cava filter system according to claim 2, characterized in that, The retention hook (13) engages with the filter body (12), wherein, The retention hook (13) includes an assembly (131) and a first hook body (132). The assembly (131) has two limiting holes (1311), and the first hook body (132) is connected to the assembly (131). The filter body (12) has two limiting legs (121), the two limiting legs (121) correspond one-to-one with the two limiting holes (1311), and the two limiting legs (121) have a first preset included angle A when in normal state; Both of the limiting legs (121) can generate elastic deformation, so that when the two limiting legs (121) pass through the two limiting holes (1311) respectively, the two limiting legs (121) will deform under the action of external force and be parallel to the axial direction of the two limiting holes (1311). After the two limiting legs (121) pass through the corresponding limiting holes (1311), the two limiting legs (121) return to the state of the first preset included angle to prevent the retention hook (13) from dislodging in the first direction before the filter (10) is implanted into the blood vessel.

4. The segmented vena cava filter system according to claim 3, characterized in that, The limiting leg (121) includes a connected assembly section (1211) and a limiting section (1212). The extension direction of the assembly section (1211) is parallel to the axial direction of the limiting hole (1311). The assembly section (1211) is used to cooperate with the limiting hole (1311). The limiting section (1212) can elastically deform relative to the assembly section (1211). The two limiting sections (1212) have a first preset included angle A between them. The filter body (12) further includes a stop block (122), which is connected to one end of the assembly section (1211) away from the limiting section (1212), and at least a portion of the outer contour of the stop block (122) protrudes from the outer contour of the assembly section (1211) to form a stop surface for the retention hook (13) to move in a second direction opposite to the first direction.

5. The segmented vena cava filter system according to claim 3, characterized in that, The range of the first preset included angle A is: 60°≤A≤70°.

6. The segmented vena cava filter system according to claim 2, characterized in that, The retention hook (13) engages with the filter body (12), wherein, The filter body (12) has a first limiting groove (123), and the retention hook (13) has a first limiting protrusion (133), the first limiting protrusion (133) engaging with the first limiting groove (123); or, The filter body (12) has a second limiting protrusion (124), and the retention hook (13) has a second limiting slot (134), which engages with the second limiting protrusion (124).

7. The segmented vena cava filter system according to claim 1, characterized in that, The recycling hook (11) includes a connected assembly column (111) and a second hook body (112), and the filter body (12) includes: The support assembly includes a plurality of support arms (125) spaced apart around one end of the assembly post (111) away from the second hook body (112), and the plurality of support arms (125) are used to fit tightly against the blood vessel wall to provide radial support force; The disengagement assembly includes a plurality of disengagement arms (126), which are spaced apart and wound around the end of the assembly post (111) away from the second hook body (112). The end of the disengagement arm (126) away from the assembly post (111) is detachably connected to the retention hook (13). The anti-displacement group includes multiple limiting arms (127), which are spaced around the end of the assembly column (111) away from the second hook body (112). The multiple limiting arms (127) are used to abut against the blood vessel wall to prevent the filter (10) from displacing and to keep the filter (10) in a centered position in the blood vessel. Among them, multiple support arms (125), multiple release arms (126), and multiple limiting arms (127) are sequentially staggered around the assembly column (111) in the circumferential direction.

8. The segmented vena cava filter system according to claim 7, characterized in that, The first length L1 of the support arm (125), the second length L2 of the release arm (126), and the third length L3 of the limiting arm (127) satisfy the following condition: L1 < L2 < L3.

9. The segmented vena cava filter system according to claim 7, characterized in that, The first width K1 of the support arm (125) is within the range of: 0.25mm ≤ K1 ≤ 0.30mm; and / or, The support arm (125) includes, in sequence, a first support section (1251), a second support section (1252), and a third support section (1253) connected in a direction away from the assembly column (111). The first support section (1251) and the second support section (1252) both extend outward in a trumpet shape, and the third support section (1253) is recessed inward toward the axial side of the assembly column (111) to prevent scratching the blood vessel wall. Wherein, the connection between the first support segment (1251) and the second support segment (1252) has a second preset included angle B, and the value range of the second preset included angle B is: 115°≤B≤130°.

10. The segmented vena cava filter system according to claim 7, characterized in that, The second width K2 of the detachment arm (126) has the following range: 0.45mm ≤ K2 ≤ 0.52mm; and / or, The opening angle C of the retention hook (13) relative to the release arm (126) is within the range of: 115°≤C≤120°.

11. The segmented vena cava filter system according to claim 7, characterized in that, The limiting arm (127) includes a limiting arm body (1271) and a forked structure (1272), wherein the forked structure (1272) is located at the end of the limiting arm body (1271) away from the assembly column (111); The first branch segment (1273) of the bifurcation structure (1272) extends along the direction of the limiting arm (127), and the second branch segment (1274) of the bifurcation structure (1272) can elastically deform relative to the first branch segment (1273). The length of the second branch segment (1274) is greater than the length of the first branch segment (1273), so that the end of the second branch segment (1274) away from the assembly post (111) protrudes from the end of the first branch segment (1273) away from the assembly post (111). The second bifurcation segment (1274) is used to abut against the blood vessel wall to prevent the filter (10) from shifting and to keep the filter (10) centered in the blood vessel.

12. The segmented vena cava filter system according to claim 7, characterized in that, The range of the bending radius R of the arc surface of the second hook body (112) is: 1.5mm≤R≤2mm.

13. The segmented vena cava filter system according to any one of claims 1 to 12, characterized in that, The recycling hook (11) is welded to the filter body (12).

14. The segmented vena cava filter system according to any one of claims 1 to 12, characterized in that, The outer peripheral surface of the filter body (12) has a first coating layer, which is used to reduce the degree of endothelialization after the filter (10) is implanted in the blood vessel for a long time, so as to reduce the recyclability of the filter (10).

15. The segmented vena cava filter system according to any one of claims 1 to 12, characterized in that, The outer peripheral surface of the retention hook (13) has a second coating layer, which is used to enable the retention hook (13) to be rapidly endothelialized in the blood vessel and at the same time inhibit excessive cell proliferation and prevent thrombosis.

16. The segmented vena cava filter system according to claim 7, characterized in that, The conveying channel includes a first conveying channel (211) and a second conveying channel (221), and the conveying unit (20) includes: Delivery sheath (21), the delivery sheath (21) having a first delivery channel (211); The ejection mechanism (22) is connected to the delivery sheath (21) and has an ejection end and a second delivery channel (221). The second delivery channel (221) is connected to the first delivery channel (211), and the ejector end is slidably disposed in the second delivery channel (221) to eject the filter (10) located in the second delivery channel (221) to the first delivery channel (211) and be delivered to the blood vessel by the first delivery channel (211).

17. The segmented vena cava filter system according to claim 16, characterized in that, The delivery sheath (21) is detachably connected to the ejection mechanism (22).

18. The segmented vena cava filter system according to claim 16, characterized in that, The conveying unit (20) also includes: A power source (23) is connected to the first conveying channel (211) to provide conveying power to the filter (10) located in the first conveying channel (211).

19. The segmented vena cava filter system according to claim 16, characterized in that, The outer surface of the delivery sheath (21) has a third coating layer, which is a hydrophilic coating.

20. The segmented vena cava filter system according to claim 16, characterized in that, The ejection mechanism (22) includes: A pre-loaded tube (222) having the second conveying channel (221); The ejector tube (223) includes a tube body (2231) and a grip handle (2232) and a limiting member (2233) located at both axial ends of the tube body (2231). One end of the tube body (2231) connected to the limiting member (2233) passes through the second conveying channel (221). The limiting member (2233) includes an assembly tube (2234) and a limiting structure (2235) located on the outer circumferential surface of the assembly tube (2234). The limiting structure (2235) has a limiting channel (2236). There are multiple limiting structures (2235), and the multiple limiting structures (2235) are arranged circumferentially around the assembly tube (2234). A limiting groove (2237) is formed between two adjacent limiting structures (2235). The number of the limiting channels (2236) corresponds one-to-one with the number of the release arms (126). The limiting channels (2236) are used for the release arms (126) to pass through, so as to limit the release arms (126) to retract inward. The number of the limiting grooves (2237) corresponds one-to-one with the number of the limiting arms (127). The limiting grooves (2237) are used for the limiting arms (127) to be inserted to limit the inward retraction of the limiting arms (127).

Images