Thrombectomy apparatus

Abstract

A thrombectomy apparatus (1), comprising a retrieval frame (10), a pulling tube (20), and an inner tube (60). The retrieval frame (10) comprises a proximal support (A) and a distal support (B) connected to the far end of the proximal support (A). The retrieval frame (10) is provided with an inner cavity penetrating through the proximal support (A) and the distal support (B). The proximal support (A) comprises a first axial section (A1) and a second axial section (A2) connected to the far end of the first axial section (A1). An oblique opening part (11) in communication with the inner cavity is formed at the near end of the first axial section (A1), such that the first axial section (A1) has a tip structure pointing to the near end. The second axial section (A2) has a circumferential outer contour. The range of the axial tensile strength ratio of the first axial section (A1) to the second axial section (A2) is [0.6, 1]. The pulling tube (20) is connected to the tip structure. The inner tube (60) slidably passes through the pulling tube (20), and the far end of the inner tube (60) is connected to the far end of the distal support (B). The inner tube (60) slides to the far end relative to the pulling tube (20), so that the retrieval frame (10) can be radially contracted. The thrombectomy apparatus (1) is less irritating to blood vessels during thrombectomy and exhibits relatively good wall apposition at the open end.

Description

Thrombus extraction device TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, and in particular to a thrombus extraction device. BACKGROUND

[0002] The background section provided herein is merely for information and is not necessarily prior art.

[0003] At present, the treatment scheme for deep venous thrombosis (DVT) mainly includes mechanical thrombus extraction, drug thrombolysis and negative pressure suction. Among them, mechanical thrombus extraction generally refers to using a thrombus extraction stent to scrape and collect the thrombus on the blood vessel wall, and then take the thrombus out of the body.

[0004] During the thrombus extraction process, the inner diameter of the deep vein gradually decreases along the moving direction of the thrombus extraction stent, and the thrombus extraction stent is radially extruded by the blood vessel. In turn, the thrombus extraction stent also radially supports the blood vessel wall. Therefore, when the thrombus extraction stent moves in the blood vessel with a smaller inner diameter, the stimulation of the thrombus extraction stent to the blood vessel is greater. Thus, in order to reduce the stimulation to the blood vessel and avoid blood vessel damage, it is expected that the radial size of the thrombus extraction stent, especially the part with greater radial support performance, can be reduced before entering the small blood vessel. The stimulation to the blood vessel wall is the greatest, so the radial size of this part is reduced to a greater extent to reduce the stimulation to the blood vessel. However, when the radial size of the part with greater radial support performance is reduced, the part with smaller radial support performance is reduced to a greater extent, for example, the radial size of the proximal inclined opening portion is reduced to a greater extent, thereby causing the inclined opening portion to not conform to the shape of the blood vessel wall, thereby not being able to effectively scrape the thrombus attached to the blood vessel wall.

[0005] SUMMARY

[0006] Therefore, it is necessary to provide a thrombus extraction device with less stimulation to the blood vessel and better conformability of the opening end during the thrombus extraction process.

[0007] A thrombus extraction device comprises:

[0008] The extraction frame comprises a proximal stent and a distal stent connected to the distal end of the proximal stent, and has an inner cavity passing through the proximal stent and the distal stent. The proximal stent comprises a first axial interval segment and a second axial interval segment connected to the distal end of the first axial interval segment. The proximal end of the first axial interval segment is formed with an inclined opening portion communicating with the inner cavity, so that the first axial interval segment has a pointed end structure pointing to the proximal end. The second axial interval segment has a circumferential outer contour. The ratio of the axial tensile strength of the first axial interval segment to the second axial interval segment is in the range of [0.6, 1];

[0009] a pulling tube connected with the tip structure;

[0010] an inner tube slidably arranged in the pulling tube, and a distal end of the inner tube is connected with a distal end of the distal support, and the inner tube slides distally relative to the pulling tube to make the retrieval frame radially contract.

[0011] When the thrombus extraction device is used to extract a thrombus, the oblique opening part is first located at a distal end of the thrombus, and then a proximal pulling force is applied to the oblique opening part by the pulling tube, so as to drive the retrieval frame to move proximally in the blood vessel. In this process, the thrombus on the inner wall of the blood vessel can be scraped off by the oblique opening part and collected in the inner cavity of the retrieval frame.

[0012] In the thrombus extraction process, before the retrieval frame enters a part of the blood vessel with a smaller inner diameter from a part of the blood vessel with a larger inner diameter, the inner tube is slid distally relative to the pulling tube to make the retrieval frame radially contract, so as to avoid the retrieval frame being excessively squeezed by the blood vessel after entering the part of the blood vessel with a smaller inner diameter, which in turn stimulates the blood vessel wall, and thus is beneficial to reducing the stimulation to the blood vessel wall.

[0013] When the retrieval frame enters the part of the blood vessel with a smaller inner diameter, the pulling tube is pulled proximally to make the retrieval frame move proximally, and in the moving process, the tip structure passes through the thrombus, and the oblique opening part can scrape off the thrombus on the blood vessel wall. Since the resistance of the tip structure passing through the thrombus is relatively small, a smaller force is used to pull the pulling tube to pull the retrieval frame to move, so as to be beneficial to avoiding that the second axial interval segment with a circumferential outer contour is severely rubbed against the blood vessel wall due to the excessive force pulling the retrieval frame, and thus is further beneficial to reducing the stimulation to the blood vessel wall.

[0014] Further, since the ratio of the axial tensile strength of the first axial interval segment to the second axial interval segment ranges from [0.6, 1], when the retrieval frame is pulled by the pulling tube, the radial contraction amplitudes of the first axial interval segment and the second axial interval segment are closer, so as to be beneficial to avoiding that the first axial interval segment excessively radially contracts when the second axial interval segment radially contracts to a smaller degree of stimulation to the blood vessel wall, which leads to poor wall adhesion of the oblique opening part or no wall adhesion, and thus leads to thrombus extraction failure.

[0015] Therefore, in the thrombus extraction process, the above-mentioned thrombus extraction device has smaller stimulation to the blood vessel wall and better wall adhesion, which is beneficial to efficiently extracting the thrombus while avoiding secondary injury to the patient. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0017] wherein:

[0018] Fig. 1 is a structural schematic diagram of a thrombectomy device in an embodiment;

[0019] Fig. 2 is a top view of Fig. 1;

[0020] Fig. 3 is a state diagram of a proximal stent in the embodiment shown in Fig. 1 when unfolded in a cutting plane along a straight line connecting a distal end of the beveled opening portion and a distal end of the distal stent;

[0021] Fig. 4 is an enlarged view of X in Fig. 3;

[0022] Fig. 5A is a state diagram of a proximal stent in another embodiment when unfolded in a cutting plane along a straight line connecting a distal end of the beveled opening portion and a distal end of the distal stent;

[0023] Fig. 5B is an enlarged view of Y in Fig. 5A;

[0024] Fig. 6 is a partial structural schematic diagram of a proximal stent in another embodiment when unfolded in a cutting plane along a straight line connecting a distal end of the beveled opening portion and a distal end of the distal stent;

[0025] Fig. 7 is a state diagram of a proximal stent in another embodiment when unfolded in a cutting plane along a straight line connecting a distal end of the beveled opening portion and a distal end of the distal stent. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0027] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by terms such as “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or replaceable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0029] In the field of interventional medical devices, the end of a medical device implanted in a human or animal body closer to the operator is generally referred to as the "proximal end", and the end farther from the operator is referred to as the "distal end", and the "proximal end" and "distal end" of any component of the medical device are defined according to this principle. "Axial" generally refers to the length direction of the medical device when it is being delivered, and "radial" generally refers to the direction of the medical device that is not parallel to its "axial" direction, and the "axial" and "radial" directions of any component of the medical device are defined according to this principle. "Circumferential" refers to the circumferential direction, i.e. the direction around the axis of the lumen structure, the cylinder.

[0030] First embodiment

[0031] Referring to FIGS. 1 and 2, the present disclosure provides a thrombus extraction device 1, which can be used to extract a thrombus in a blood vessel of a patient. The thrombus extraction device 1 comprises an extraction frame 10, a pulling tube 20 and a delivery sheath 30, wherein the distal end of the pulling tube 20 is connected to the proximal end of the extraction frame 10, and the delivery sheath 30 is slidably sleeved on the pulling tube 20. The delivery sheath 30 is a tubular structure and can slide axially along the pulling tube 20 to load and release the extraction frame 10.

[0032] The extraction frame 10 is a mesh structure having an inner cavity. The extraction frame 10 can be formed by weaving a wire and then setting, or by cutting a hollow tube and then setting. The wire can be a nickel-titanium alloy wire, a stainless steel wire or other metal wire. The hollow tube can be a nickel-titanium alloy tube, a stainless steel tube or other metal tube, or a polymer tube.

[0033] The extraction frame 10 has radial compressibility and can be compressed to a loading size under the constraint force (radial compression force on the extraction frame 10 or axial tensile force applied to both ends of the extraction frame 10) so as to be loaded in the delivery sheath 30, thereby being delivered in the blood vessel of the patient through the delivery sheath 30. When reaching the intended position, the delivery sheath 30 is moved proximally relative to the extraction frame 10 and the pulling tube 20 to expose the extraction frame 10.

[0034] The retrieval rack 10 is self-expandable, and can expand to a radially expanded state after the constraint force acting on the retrieval rack 10 is removed. For example, after the delivery sheath 30 is removed from the retrieval rack 10, the retrieval rack 10 can expand radially to a radially expanded state.

[0035] Referring to FIG. 2, the retrieval rack 10 includes a proximal support A and a distal support B connected in an axial direction. The proximal support A is located proximally to the distal support B, and the proximal support A and the distal support B are both part of a mesh structure. The proximal support A and the distal support B are connected and jointly form an inner cavity of the retrieval rack 10. The inner cavity of the retrieval rack 10 extends through the proximal support A and the distal support B. A proximal end of the proximal support A forms an oblique opening portion 11 communicating with the inner cavity. The oblique opening portion 11 is a circumferentially closed structure, and can scrape a thrombus when moving in a blood vessel under the action of an external force.

[0036] Referring to FIG. 2, the proximal support A includes a first axial interval segment A1 and a second axial interval segment A2 connected in sequence from proximal to distal. A proximal end of the first axial interval segment A1 forms the oblique opening portion 11 communicating with the inner cavity, so that the first axial interval segment A1 has a pointed end structure pointing to the proximal end. An axial length of the oblique opening portion 11 is equal to an axial length of the first axial interval segment A1. A proximal end of the second axial interval segment A2 is connected to the first axial interval segment A1, and the second axial interval segment A2 has a circumferential outer contour. A ratio of axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2 ranges from 0.6 to 1, so that when axial tensile forces are applied to both ends of the retrieval rack 10, a ratio of lengths of the first axial interval segment A1 and the second axial interval segment A2 that are axially stretched ranges from 0.6 to 1.

[0037] The ratio of the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2 can be measured by the following method: axial tensile forces are applied to both ends of the retrieval rack 10, so that the first axial interval segment A1 and the second axial interval segment A2 are both axially elongated and radially shrinkage deformed. While the forces are maintained, values of axial lengths of the first axial interval segment A1 and the second axial interval segment A2 after being axially stretched are recorded, and then a ratio of the axial lengths of the first axial interval segment A1 and the second axial interval segment A2 is calculated, which is the ratio of the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2.

[0038] Please continue to refer to FIG. 1 and FIG. 2, the oblique opening part 11 includes a distal end 111 and a proximal end 112, and the axial distance between the distal end 111 and the proximal end 112 is greater than zero. The proximal end 112 of the oblique opening part 11 is a pointed end structure. The oblique opening part 11 is a circumferentially closed structure, and when moving in the blood vessel under the action of an external force, it can scrape the thrombus in the circumferential direction. When the thrombus removal device 10 is located in the blood vessel and the constraint force acting on the thrombus removal device 10 is removed, the thrombus removal device 10 can self-expand to a radially expanded state, so that the oblique opening part 11 is in close contact with the inner wall of the blood vessel.

[0039] Please refer to FIG. 1 and FIG. 2, the thrombus removal device 1 further comprises a sleeve 41 connected to the proximal end 112 of the oblique opening part 11 through a connecting strip 51.

[0040] The pulling tube 20 is a hollow tubular structure. The distal end of the pulling tube 20 is connected to the sleeve 41, so that the pulling tube 20 can exert a force on the thrombus removal device 10 through the sleeve 41 and the connecting strip 51 and the proximal end 112 of the oblique opening part 11, so that the thrombus removal device 10 can be pushed to the distal end of the thrombus during thrombus removal, and when the thrombus removal device 10 is transported to the desired position (for example, at the distal end of the thrombus), a pulling force is exerted on the thrombus removal device 10 to move the thrombus removal device 10 in the blood vessel from the distal end to the proximal end to scrape the thrombus.

[0041] Please refer to FIG. 1 and FIG. 2, the thrombus removal device 1 further comprises an inner tube 60, which is slidably arranged in the pulling tube 20, and the distal end of the inner tube 60 is connected to the distal end of the distal support B. Sliding the inner tube 60 distally relative to the pulling tube 20 can reduce the outer profile of the thrombus removal device 10 in the radial direction.

[0042] Please refer to FIG. 3, when the thrombus removal device 10 is planarly expanded along a straight line connecting the distal end 111 of the oblique opening part 11 and the distal end 181 of the distal support B as a cutting line, the first axial interval A1 is a first mesh structure with a triangular profile. The proximal end 112 of the oblique opening part 11 is one vertex of the triangle, and the two edges 113 of the triangle extending distally from the vertex form the oblique opening part 11 when closed. The first mesh structure includes a plurality of first meshes 12, which are surrounded by the two edges 113 and a plurality of first mesh rods 121.

[0043] The pointed end structure of the first axial interval A1 points to the proximal end, and in the above-mentioned planarly expanded state, the first axial interval A1 is a first mesh structure surrounded by the two edges 113 and a plurality of first mesh rods 121, so that during thrombus removal, the first axial interval A1 can better overcome the thrombus resistance and smoothly remove the thrombus. Moreover, the first axial interval A1 of such structure has a certain structural stability, which is beneficial to avoid deformation and effectively remove the thrombus.

[0044] In one embodiment, the ratio of the axial tensile strength of the first axial section A1 to the axial tensile strength of the second axial section A2 is in the range of 0.6 to 1.

[0045] During the thrombectomy using the thrombectomy device 1, the beveled opening portion 11 of the retrieval rack 10 is first positioned at the distal end of the thrombus, and then the restraining force acting on the retrieval rack 10 is removed, and the retrieval rack 10 is self-expanded so that the beveled opening portion 11 is attached to the blood vessel wall. Since the beveled opening portion 11 is a circumferentially closed structure, the beveled opening portion 11 can be attached to the blood vessel wall in the circumferential 360° direction. A pulling force is applied to the pulling tube 20 to drive the retrieval rack 10 to move proximally, thereby cutting the thrombus on the blood vessel wall. The thrombus cut off by the beveled opening portion 11 enters the inner cavity of the retrieval rack 10 through the beveled opening portion 11 and is captured, thereby being taken out of the body by the retrieval rack 10.

[0046] During the thrombectomy, before the retrieval rack 10 enters the part with a smaller inner diameter from the part with a larger inner diameter, a distally directed pushing force is applied to the inner tube 60 to make the inner tube 60 slide distally relative to the pulling tube 20 to make the retrieval rack 10 radially contract, so as to avoid the retrieval rack 10 being excessively squeezed by the blood vessel after entering the part with a smaller inner diameter of the blood vessel with a larger radial profile, thereby facilitating to reduce the stimulation to the blood vessel.

[0047] When the retrieval rack 10 is subjected to a proximally directed pulling force for thrombectomy in the blood vessel with a smaller inner diameter, since the resistance of the pointed end structure passing through the thrombus is relatively small, it is beneficial to avoid excessive force pulling the retrieval rack 10 to cause the second axial section A2 with a circumferential outer profile to be severely rubbed against the blood vessel wall, thereby further facilitating to reduce the stimulation to the blood vessel wall.

[0048] Further, when the retrieval rack 10 is subjected to an axial pulling force, since the ratio of the axial tensile strength of the first axial section A1 to the axial tensile strength of the second axial section A2 is in the range of [0.6, 1], the difference between the axial tensile strengths of the first axial section A1 and the second axial section A2 is small, so that the radial contraction amplitudes of the first axial section A1 and the second axial section A2 are closer, thereby facilitating to avoid that when the second axial section A2 is radially contracted to a degree that the stimulation to the blood vessel wall is small, the first axial section A1 is excessively radially contracted to cause the beveled opening portion 11 to have poor or no wall-attaching property, thereby leading to thrombectomy failure.

[0049] Please refer to Fig. 2, the second axial section segment A2 is cylindrical, having a cylindrical inner cavity with two open ends. The distal end of the second axial section segment A2 is connected with the proximal end of the distal end support B. The end of the second axial section segment A2 away from the distal end support B is connected with the first axial section segment A1. The second axial section segment A2 is cylindrical, having a circumferential outer contour, so that the second axial section segment A2 can better keep in contact with the blood vessel wall during the thrombectomy, which is conducive to avoiding thrombus escape, thereby improving the thrombectomy efficiency.

[0050] Please continue to refer to Fig. 2, the distal end support B is conical, the smaller diameter end of the distal end support B is located at the distal end, and the larger diameter end is located at the proximal end. The distal end support B is connected with the distal end of the second axial section segment A2. The diameter of the distal end support B except the part connected with the proximal end support A is smaller than the diameter of the proximal end support A, so that the distal end support B has smaller stimulation to the blood vessel during the thrombectomy. The distal end support B has a conical inner cavity, and the larger diameter end of the distal end support B is an open end, and the smaller diameter end is a closed end. The closed end is the closed end of the extraction frame 10.

[0051] Please refer to Fig. 3, when the extraction frame 10 is planarly unfolded along the straight line connecting the distal end of the inclined opening part 11 and the distal end 181 of the distal end support B as the cutting line, the second axial section segment A2 is a second mesh structure surrounded by two opposite wave lines S, the proximal ends of the two wave lines S are connected with the distal ends of the two edges 113 respectively, and the maximum radial distance between the two opposite wave lines S is equal to the radial distance of the distal ends of the two edges 113. The second mesh structure includes a plurality of second meshes 13 surrounded by a plurality of second net rods 131.

[0052] The ratio of the sum of the volumes of the two edges 113 and the plurality of first net rods 121 of the first axial section segment A1 to the sum of the volumes of the plurality of second net rods 131 of the second axial section segment A2 is 0.6-1, so that the ratio of the axial tensile strength of the first axial section segment A1 to the second axial section segment A2 is 0.6-1, and then when the two ends of the extraction frame 10 are subjected to tension, the radial contraction amplitudes of the first axial section segment A1 and the second axial section segment A2 are closer, so as to facilitate the extraction frame 10 to reduce the stimulation of the second axial section segment A2 to the blood vessel inner wall when the extraction frame 10 is used for thrombectomy at the part with smaller blood vessel inner diameter, and the inclined opening part 11 can keep in contact with the blood vessel inner wall.

[0053] Referring to FIG. 3, in an embodiment, the first mesh structure is provided with a reinforcing structure 14 to increase the axial tensile strength of the first axial section A1. In an embodiment, the ratio of the sum of the volumes of the two edges 113, the plurality of first mesh rods 121 and the reinforcing structure 14 in the first axial section A1 to the sum of the volumes of the plurality of second mesh rods in the second axial section A2 is 0.65-1, so that the ratio of the axial tensile strength of the first axial section A1 to the second axial section A2 is 0.65-1, and when the two ends of the frame 10 are subjected to axial tension and shrink in the radial direction, the amplitude of the radial shrinkage of the first axial section A1 and the second axial section A2 is closer, thereby facilitating the avoidance of excessive radial shrinkage of the first axial section A1 when the second axial section A2 is radially shrunk to a degree at which the stimulation to the blood vessel wall is small, which leads to poor or no wall adhesion of the beveled opening portion 11 and thus thrombectomy failure.

[0054] Referring to FIG. 3, the plurality of first meshes 12 includes a proximal-most mesh, which is marked as 12’ for distinction from other first meshes 12. Referring to FIG. 4, in an embodiment, the proximal-most mesh 12’ is a quadrilateral mesh formed by a part of the two edges 113 and two first mesh rods 121, and the proximal vertex of the proximal-most mesh 12’ is the proximal vertex of the first mesh structure. For ease of description, the part of each edge 113 used to form the proximal-most mesh 12’ is named as a proximal mesh rod, and the first mesh rod used to form the proximal-most mesh 12’ is named as a distal mesh rod. To distinguish the proximal mesh rod and the distal mesh rod from other parts of the edge 113 and other first mesh rods 121, the proximal mesh rod and the distal mesh rod are specially marked, and the proximal mesh rod is marked as 113’, and the distal mesh rod is marked as 121’.

[0055] Referring to FIGS. 3 and 4, the reinforcing structure 14 includes reinforcing rods 141 arranged in the proximal-most mesh 12’. The reinforcing rods 141 are rod-shaped structures with a certain rigidity. In the embodiment shown in FIGS. 3 and 4, the number of reinforcing rods 141 is two. The two ends of each reinforcing rod 141 are fixedly connected to two edges 113 and two first mesh rods 121, respectively. In this embodiment, the two ends of each reinforcing rod 141 are fixedly connected to one proximal mesh rod 113’ and one distal mesh rod 121’, respectively, and the two reinforcing rods 141 cross each other and are fixedly connected at the crossing.

[0056] When the extraction rack 10 is planarly unfolded with the straight line connecting the distal end 111 of the oblique opening part 11 and the distal end 181 of the distal end support B as the shearing line, each reinforcing rod 141 forms an angle a with the straight line L passing through the proximal end 112 of the oblique opening part 11 and the distal end 181 of the distal end support B, and the angle a ranges from [0°, 90°]. In an embodiment, the proximal-most grid 12' has an axial diagonal line coinciding with the straight line L.

[0057] When the value of the angle a is in [0°, 12°), the length of the reinforcing rod 141 is greater than or equal to 1 / 2 of the axial length of the proximal-most grid 12'.

[0058] When the value of the angle a is in [12°, 74°], the minimum distance from the connection point of each reinforcing rod 141 to two of the first grid rods 121 and two of the edges 113 to the end of the two of the first grid rods 121 and the two of the edges 113 is greater than or equal to 1 / 5 of the length of the first grid rod 121 or the edge 113 where it is located. It should be noted that the "minimum distance from the connection point of each reinforcing rod 141 to two of the first grid rods 121 and two of the edges 113 to the end of the two of the first grid rods 121 and the two of the edges 113" refers to the minimum distance from the connection point of each reinforcing rod 141 to two of the distal grid rods 121' and two of the proximal grid rods 113' to the end of the two of the distal grid rods 121' and the two of the proximal grid rods 113'; and "greater than or equal to 1 / 5 of the length of the first grid rod 121 or the edge 113 where it is located" refers to greater than or equal to 1 / 5 of the length of the distal grid rod 121' or the proximal grid rod 113' where it is located.

[0059] When the value of the angle a is in (74°, 90°], the minimum distance from the connection point of each reinforcing rod 141 to two of the first grid rods 121 and two of the edges 113 to the end of the two of the first grid rods 121 and the two of the edges 113 is greater than or equal to 1 / 5 of the length of the first grid rod 121 or the edge 113 where it is located, and the length of the reinforcing rod 141 is greater than or equal to 1 / 2 of the width of the proximal-most grid 12'. That is, the minimum distance from the connection point of each reinforcing rod 141 to two of the distal grid rods 121' and two of the proximal grid rods 113' to the end of the two of the distal grid rods 121' and the two of the proximal grid rods 113' is greater than or equal to 1 / 5 of the length of the distal grid rod 121' or the proximal grid rod 113' where it is located, and the length of the reinforcing rod 141 is greater than or equal to 1 / 2 of the width of the proximal-most grid 12'.

[0060] The ratio of the sum of the volumes of the two edges 113 (including the proximal mesh rod 113'), the plurality of first mesh rods 121 (including the distal mesh rod 121'), and the reinforcing rod 141 in the first axial interval segment A1 to the sum of the volumes of the plurality of second mesh rods 131 in the second axial interval segment A2 is 0.65-1, so that the ratio of the axial tensile strength of the first axial interval segment A1 to the second axial interval segment A2 is 0.65-1, thereby further reducing the difference in axial tensile strength between the first axial interval segment A1 and the second axial interval segment A2. Before entering a part of the blood vessel with a smaller inner diameter, the two ends of the retrieval rack 10 are subjected to axial tension by pulling the tube 20 and the inner tube 60 to reduce the radial size of the retrieval rack 10. The difference in axial tensile strength between the first axial interval segment A1 and the second axial interval segment A2 is small, which can make the radial shrinkage of the first axial interval segment A1 and the second axial interval segment A2 more close, thereby facilitating to avoid that when the second axial interval segment A2 is radially contracted to a degree that the stimulation to the blood vessel wall is small, the first axial interval segment A1 is excessively radially contracted, resulting in poor or no wall adhesion of the oblique opening part 11, thereby leading to thrombectomy failure.

[0061] The axial length of the proximal-most mesh 12' refers to the maximum length of the proximal-most mesh 12' along the axial direction of the retrieval rack 10. The width of the proximal-most mesh 12' refers to the maximum dimension of the proximal-most mesh 12' in the direction perpendicular to the axial direction when the retrieval rack 10 is flatly expanded.

[0062] In other embodiments, the number of reinforcing rods 141 described above can be one or more. When the number of reinforcing rods 141 in the proximal-most mesh 12' is multiple, the reinforcing rods 141 can be parallel to each other or intersect with each other. When two reinforcing rods 141 intersect with each other, the two reinforcing rods 141 intersecting with each other are fixedly connected at the intersection. And when the number of reinforcing rods 141 in the proximal-most mesh 12' is multiple, the angles a formed by different reinforcing rods 141 and the straight line L can be in the same range or different ranges of the above three angle ranges (i.e. [0°, 12°), [12°, 74°] and (74°, 90°]).

[0063] In the process of applying a pulling force to the pull tube 20 of the present embodiment to drive the retrieval rack 10 to move proximally, when the first mesh 12 of the proximal support A is stretched to be longer or has a tendency to be longer, since the reinforcing rods 141 have a certain rigidity, the reinforcing rods 141 are located in the first axial interval section A1, and the two ends of each reinforcing rod 141 are respectively fixedly connected with two mesh rods (specifically, any two of the two proximal mesh rods 113' and the two distal mesh rods 121') of the nearest end mesh 12' in the first axial interval section A1, so that the reinforcing rod 141 can provide a binding force to the nearest end mesh 12', and therefore the arrangement of the reinforcing rod 141 in the nearest end mesh 12' can reduce the degree of axial elongation of the nearest end mesh 12' or avoid axial elongation. Moreover, since the nearest end mesh 12' is a direct force receiving part, the arrangement of the reinforcing rod 141 resists a part of the stretching force, thereby weakening the stretching force transmitted to the other first meshes 12 in the first axial interval section A1, slowing down or avoiding the axial elongation of the other meshes 12 in the first axial interval section A1, that is, the arrangement of the reinforcing rod 141 increases the axial anti-stretching strength of the first axial interval section A1. Therefore, the reinforcing rod 141 can reduce the degree of axial elongation of the first axial interval section A1 during the driving of the retrieval rack 10 in the blood vessel, that is, reduce the degree of axial elongation of the beveled opening portion 11, and further reduce the degree of radial inward contraction of the beveled opening portion 11 due to the axial elongation, thereby playing a role in improving the wall adhesion of the beveled opening portion 11. Moreover, since the arrangement of the reinforcing rod 141 increases the axial anti-stretching strength of the first axial interval section A1, the axial anti-stretching strengths of the first axial interval section A1 and the second axial interval section A2 are closer, and before the retrieval rack 10 enters a part of the blood vessel with a smaller diameter, when the retrieval rack 10 is radially contracted by the pull tube 20 and the inner tube 60 applying an axial stretching force to the retrieval rack 10 to drive the retrieval rack 10 to move proximally, the degrees of radial contraction of the first axial interval section A1 and the second axial interval section A2 are closer, thereby being able to reduce the stimulation of the second axial interval section A2 to the blood vessel, and also being able to keep the beveled opening portion 11 in close contact with the inner wall of the blood vessel.

[0064] When the proximal stent A is unfolded in a planar state, the reinforcing rod 141 and the straight line L form an included angle a, and the included angle a is in the range of [0°, 90°]. When the value of the included angle a is in the range of [0°, 12°), the length of the reinforcing rod 141 is greater than or equal to 1 / 2 of the axial length of the proximal mesh 12', so that the reinforcing rod 141 has sufficient length and thus has sufficient supporting performance, thereby increasing the axial tensile strength of the first axial interval segment A1. Moreover, when the value of the included angle a is in the range of [0°, 12°) and the length of the reinforcing rod 141 is greater than or equal to 1 / 2 of the axial length of the proximal mesh 12', the reinforcing rod 141 can provide a binding force to a larger area of the proximal mesh 12' to increase the axial tensile strength of the proximal mesh 12', so as to avoid the decrease in the wall adhesion of the oblique opening portion 11 due to the large elongation during the thrombectomy. Moreover, the reinforcing rod 141 can provide a binding force to a larger area of the proximal mesh 12' to increase the axial tensile strength of the proximal mesh 12', thereby increasing the axial tensile strength of the first axial interval segment A1, reducing the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2, and making the radial contraction amplitudes of the first axial interval segment A1 and the second axial interval segment A2 more consistent when the radial size of the extraction frame 10 is reduced. During the thrombectomy in a blood vessel with a small inner diameter, the first axial interval segment A1 is prevented from being excessively radially contracted to cause poor wall adhesion or no wall adhesion of the oblique opening portion 11 and thus cause the thrombectomy failure when the second axial interval segment A2 is radially contracted to a small degree of stimulation to the blood vessel wall. Unlike this, when the value of the included angle a is in the range, but the length of the reinforcing rod 141 is small (for example, less than 1 / 2 of the axial length of the proximal mesh 12'), for example, a = 0°, and the length of the reinforcing rod 141 is equal to 1 / 4 of the axial length of the proximal mesh 12', the length of the reinforcing rod 141 is small, so that the reinforcing rod 141 has a small supporting effect on the proximal mesh 12', and the reinforcing rod 141 can only provide a binding force to a small area of the proximal mesh 12', i.e., has a small effect on reducing the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2. When the oblique opening portion 11 is subjected to a tensile force during the thrombectomy, the effect of slowing down the large elongation of the oblique opening portion 11 to slow down the degree of separation from the inner wall of the blood vessel is small, and the effect of reducing the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2 is small.

[0065] Similarly, when the value of the included angle a is in the range of [12°, 74°], the minimum distance between the connection point of each reinforcing rod 141 to the mesh rod (for example, the proximal mesh rod 113' or the distal mesh rod 121') to the end of the mesh rod is greater than or equal to 1 / 5 of the length of the mesh rod, so that the length of the reinforcing rod is longer, and the reinforcing rod can provide a binding force to a larger area of the proximal mesh 12' to avoid a decrease in the adhesion of the diagonal opening portion 11 due to a larger elongation during the stentriever procedure. Moreover, the reinforcing rod 141 can provide a binding force to a larger area of the proximal mesh 12' to also reduce the difference in the axial tensile strength of the first axial interval section A1 and the second axial interval section A2, so that the stentriever 10 can make the reduction in the radial size of the stentriever 10, and the reduction in the first axial interval section A1 and the second axial interval section A2 is closer, and the stentriever 10 can reduce the stimulation of the blood vessel while also maintaining the adhesion of the diagonal opening portion 11 to the inner wall of the blood vessel. Similarly, when the value of the included angle a is in the range of (74°, 90°], the minimum distance between the connection point of each reinforcing rod 141 to the mesh rod to the end of the mesh rod is greater than or equal to 1 / 5 of the length of the mesh rod, and the length of the reinforcing rod 141 is greater than or equal to 1 / 2 of the width of the proximal mesh 12', so that the reinforcing rod 141 can provide a binding force to a larger area of the proximal mesh 12' to avoid a decrease in the adhesion of the diagonal opening portion 11 due to a larger elongation during the stentriever procedure. Moreover, the stentriever 10 can reduce the radial size of the stentriever 10 to facilitate the stentriever procedure in a part of the blood vessel with a smaller inner diameter, and the reinforcing rod 141 of the stentriever 10 can provide a binding force to a larger area of the proximal mesh 12' to increase the axial tensile strength of the first axial interval section A1 to reduce the difference in the axial tensile strength between the first axial interval section A1 and the second axial interval section A2, so that the first axial interval section A1 and the second axial interval section A2 are closer in the radial reduction, and the stentriever 10 can reduce the stimulation of the blood vessel while also maintaining the adhesion of the diagonal opening portion 11 to the inner wall of the blood vessel.

[0066] In the embodiments shown in FIG. 3 and FIG. 4, the proximal-most grid 12' is a quadrilateral grid, two reinforcing rods 141 are arranged in the proximal-most grid 12', two ends of each reinforcing rod 141 are connected to two non-directly connected rods (i.e. one proximal rod 113' and one distal rod 121') of the quadrilateral grid respectively, and the angle a formed by each reinforcing rod 141 and the straight line L is in the range of [12°, 74°], the minimum distance between the connection point of each reinforcing rod 141 and the rod (proximal rod 113' or distal rod 121') and the end of the rod is greater than or equal to 1 / 5 of the length of the rod, so that the two reinforcing rods 141 can exert a binding force on a larger area of the proximal-most grid 12', and the structural stability of the proximal-most grid 12' is higher under the binding action of the two reinforcing rods 141, which is more conducive to improving the axial tensile strength of the first axial interval section A1 and reducing the difference between the axial tensile strengths of the first axial interval section A1 and the second axial interval section A2. Moreover, the two reinforcing rods 141 intersect and are connected at the intersection, which can further increase the structural stability of the proximal-most grid 12' and is conducive to increasing the tensile strength of the proximal-most grid 12' and reducing the difference between the axial tensile strengths of the first axial interval section A1 and the second axial interval section A2.

[0067] Please refer to FIG. 2, the pulling tube 20 is connected to the proximal end 112 of the oblique opening portion 11 through the collar 41 and the connecting strip 51, so when the pulling tube 20 exerts a pulling force on the extraction frame 10, the action point of the pulling force is the proximal end 112 of the oblique opening portion 11, so under the same pulling force, the deformation of the first grid 12 closer to the proximal end 112 in the circumferential and axial directions is greater, so under the same conditions, the deformation of the proximal-most grid 12' is relatively larger than that of the other first grids 12 intersected by the straight line L, and the reinforcing rod 141 is arranged in all the first grids 12 intersected by the straight line L (including the proximal-most grid 12'), which is more conducive to increasing the axial tensile strength of the first axial interval section A1 and reducing the difference between the axial tensile strengths of the first axial interval section A1 and the second axial interval section A2.

[0068] In the embodiment shown in FIG. 3, the reinforcing rod 141 is arranged in the most proximal mesh 12' in the first axial section A1. With other conditions being the same (such as the material of the reinforcing rod 141, the rod width of the reinforcing rod 141, the thickness of the reinforcing rod 141, the angle size of the included angle a formed by the reinforcing rod 141 and the straight line L, etc.), arranging the reinforcing rod 141 in the most proximal mesh 12' in the first axial section A1 is more advantageous for improving the overall axial tensile strength of the first axial section A1, and is more advantageous for reducing the extent of axial elongation of the oblique opening portion 11 during dragging of the tube 20 to move the frame 10 in the blood vessel, thereby being advantageous for improving the wall-adhesion of the oblique opening portion 11. Moreover, when an axial tensile force is applied to both ends of the frame 10 to reduce the radial dimension of the frame 10, the greater the axial tensile strength of the first axial section A1, the more advantageous for reducing the difference between the axial tensile strengths of the first axial section A1 and the second axial section A2, the more similar the extent of reduction of the radial dimensions of the first axial section A1 and the second axial section A2 by the frame 10, the blood vessel stimulation by the second axial section A2 can be reduced, and the oblique opening portion 11 can be kept adhered to the inner wall of the blood vessel.

[0069] Thus, in an embodiment, the reinforcing rod 141 is arranged in the most proximal mesh 12' and the other first meshes 12 that are crossed by the straight line L, and the thickness of the reinforcing rod 141 in the most proximal mesh 12' is greater than the thickness of the reinforcing rod 141 in the other first meshes 12, so that the ratio of the axial tensile strengths of the first axial section A1 and the second axial section A2 is set to [0.7, 1], so that the difference between the axial tensile strengths of the first axial section A1 and the second axial section A2 is further reduced, and thereby the extent of reduction of the radial dimensions of the first axial section A1 and the second axial section A2 by the frame 10 when the radial dimension of the frame 10 is reduced is more similar, the blood vessel stimulation by the second axial section A2 at the part with smaller inner diameter of the blood vessel can be reduced, and the oblique opening portion 11 can be kept adhered to the inner wall of the blood vessel.

[0070] Second embodiment

[0071] Please refer to FIG. 5A and FIG. 5B, in an embodiment, at least one first mesh 12 in the axial section segment where the oblique opening part 11 is located is provided with a reinforcing rod 141, at least one first mesh 12 is provided with at least one reinforcing rod 141, the angle b between each reinforcing rod 141 and the straight line L is in the range of [12°, 74°], and the minimum distance between the connecting point of each reinforcing rod 141 and the end of the first mesh rod 121 is greater than or equal to 1 / 5 of the length of the first mesh rod 121, so that the reinforcing rod 141 has a longer length and can provide restraint force to a larger area of the mesh 12 connected thereto, so as to increase the axial tensile strength of the first axial section segment A1 and reduce the difference between the axial tensile strengths of the first axial section segment A1 and the second axial section segment A2, so that the radial size of the first axial section segment A1 and the radial size of the second axial section segment A2 are reduced more closely when the radial size of the retrieval frame 10 is reduced, which can reduce the stimulation of the retrieval frame 10 to the part with smaller inner diameter of the blood vessel, and also can make the oblique opening part keep close contact with the inner wall of the blood vessel. At the same time, the angle b between each reinforcing rod 141 and the straight line L is in the range of [12°, 74°], and the minimum distance between the connecting point of each reinforcing rod 141 and the end of the first mesh rod 121 is greater than or equal to 1 / 5 of the length of the first mesh rod 121, so that the first mesh 12 connected with the reinforcing rod 141 can be compressed in the circumferential direction, so as to facilitate the loading of the retrieval frame 10 into the delivery sheath 30 with smaller diameter, thereby facilitating the delivery in the body cavity of the patient.

[0072] The area covered by the proximal-most mesh 12' has a pointed structure pointing to the proximal end, i.e., the area covered by the proximal-most mesh 12' is smaller. Even when a = 0°, the reinforcing rod 141 is parallel to the straight line L, and after the two ends of the reinforcing rod 141 are fixedly connected to the proximal mesh rod 113' and the distal mesh rod 121', the axial distance between the connecting points of the first mesh 12 fixedly connected to the two ends of the reinforcing rod 141 is basically locked. In this case, the part of the first mesh 12 connected with the reinforcing rod 141 cannot be axially elongated or can be elongated only in a small range under the action of tension, thereby causing the first mesh 12 fixedly connected with the reinforcing rod 141 to be unable to be radially compressed or can be radially compressed only in a small range, but the size of the area covered by the proximal-most mesh 12' in the radial direction is still smaller, and the retrieval frame 10 can be loaded into the delivery sheath 30 with smaller diameter, thereby facilitating the delivery in the body cavity of the patient.

[0073] Even when a = 90°, the width between the two connection points of the proximal-most mesh 12' and the reinforcing rod 141 is substantially locked, in this case, and thus the portion of the proximal-most mesh 12' connected to the reinforcing rod 141 cannot be reduced in width under tension or can only be reduced in width to a small extent, and thus the proximal-most mesh 12' connected to the reinforcing rod 141 cannot be radially compressed or can only be radially compressed to a small extent, but the size of the area covered by the proximal-most mesh 12' in the radial direction is still small, and the retrieval device 10 can be loaded into a delivery sheath 30 with a small diameter to facilitate delivery into the body cavity of a patient.

[0074] However, the area covered by all the first meshes 12 in the first axial interval segment A1 except the proximal-most mesh 12' is larger than the area covered by the proximal-most mesh 12', and the area covered by all the first meshes 12 except the proximal-most mesh 12' should be radially compressed as much as possible to reduce the sheath size.

[0075] Therefore, in order to balance the tensile resistance and the sheath size reduction, when the reinforcing rod 141 is provided in the meshes 12 in the first axial interval segment A1 except the proximal-most mesh 12', the angle b between the reinforcing rod 141 and the straight line L is not equal to 0° or 90°.

[0076] In this embodiment, the value of the included angle b is in the range of [12°, 74°], so that after the reinforcing rods 141 are arranged in the first meshes 12 in the first axial interval section A1 except the proximal-most mesh 12', the first meshes 12 in the first axial interval section A1 can still be compressed radially to a large extent to facilitate the entry of the delivery sheath 30, and thus even if the reinforcing rods 141 are arranged in at least one of the first meshes 12 in the first axial interval section A1 except the proximal-most mesh 12', the sheath entry size of the retrieval rack 10 will not be greatly increased. In this embodiment, the minimum distance between the connection point of each reinforcing rod 141 and the end of the first mesh rod 121 is greater than or equal to 1 / 5 of the length of the first mesh rod 121, so that the reinforcing rod 141 has a relatively long length, which is conducive to improving the axial tensile resistance of the first axial interval section A1 to reduce the difference between the axial tensile resistance of the first axial interval section A1 and the second axial interval section A2, so that the retrieval rack 10 can still avoid the decrease in wall adhesion caused by the large elongation of the oblique opening portion 11 of the retrieval rack 10 during the retrieval process, while having a smaller sheath entry size. In addition, when the retrieval rack 10 enters a blood vessel with a small inner diameter, since the difference between the axial tensile resistance of the first axial interval section A1 and the second axial interval section A2 is small, the first axial interval section A1 and the second axial interval section A2 are axially stretched, and the radial size of the first axial interval section A1 and the second axial interval section A2 is reduced to a similar extent, so that the second axial interval section A2 can reduce the stimulation to the blood vessel, and the oblique opening portion 11 can also be kept in close contact with the inner wall of the blood vessel.

[0077] It should be noted that when a part of the first mesh 12 in which the reinforcing rod 141 is located is located in the first axial interval section A1 and another part is located in the second axial interval section A2, it also belongs to the case defined in the above "the reinforcing rod 141 is arranged in the first mesh 12 in the first axial interval section A1". In this embodiment, at least a part of the first axial interval section A1 (i.e., the first mesh fixedly connected with the reinforcing rod 141) can be constrained by the reinforcing rod 141. During the process of applying tension by the pull tube 20 to drive the retrieval rack 10 to move proximally, the reinforcing rod 141 can reduce the elongation of the first axial interval section A1 in the axial direction, thereby improving the wall adhesion of the oblique opening portion 11, and when the pull tube 20 and the inner tube 60 jointly apply axial tensile force to both ends of the retrieval rack 10, the first axial interval section A1 and the second axial interval section A2 are more similar in the radial contraction range, so as to reduce the stimulation of the retrieval rack 10 to the blood vessel with a small inner diameter and keep the oblique opening portion 11 in close contact with the inner wall of the blood vessel.

[0078] In the embodiment shown in FIGS. 5A and 5B, each first mesh 12 in which the reinforcing rod 141 is located (including the most proximal mesh 12') is crossed by the straight line L, and since the force applied to the pulling tube 20 is an axial tensile force, i.e., the force acting on the proximal end 112 is an axial tensile force, and the straight line L extends in the axial direction, the reinforcing rod 141 is arranged in the first mesh 12 crossed by the straight line L, which can better resist the axial tensile force to increase the axial tensile strength of the first axial interval segment A1 and reduce the difference in the axial tensile strength between the first axial interval segment A1 and the second axial interval segment A2.

[0079] In other embodiments, even if only a part of the first mesh 12 in which the reinforcing rod 141 is located is crossed by the straight line L, the axial tensile strength of the first axial interval segment A1 can be improved as a whole and the difference in the axial tensile strength between the first axial interval segment A1 and the second axial interval segment A2 can be reduced.

[0080] Third Embodiment

[0081] Referring to FIG. 6, the third embodiment differs from the first embodiment in that the most proximal mesh 12' is a quadrilateral mesh, and two reinforcing rods 141 are arranged in the most proximal mesh 12', one end of one of the reinforcing rods 141 is connected to two vertices of the quadrilateral mesh, and the other end of the reinforcing rod 141 is connected to the other two vertices of the quadrilateral mesh. Furthermore, the angle a between one of the reinforcing rods 141 and the straight line L is 0°, and the angle a between the other reinforcing rod 141 and the straight line L is 90°, the two reinforcing rods 141 intersect, and the two reinforcing rods 141 are connected at the intersection. Thus, during the stent retrieval process, when the retrieval device 10 moves under the action of the tensile force, the most proximal mesh 12' cannot be stretched in the axial direction or can only be stretched to a small extent, and cannot be compressed in the circumferential direction or can only be compressed to a small extent, so that the structural stability of the most proximal mesh 12' is greatly improved under the joint action of the two reinforcing rods 141, and the deformation amount of the most proximal mesh 12' under the action of the tensile force in the axial direction and the radial direction is very small or the most proximal mesh 12' is not deformed, so that the axial tensile strength of the first axial interval segment A1 is greatly improved and the difference between the first axial interval segment A1 and the second axial interval segment A2 is greatly reduced, thereby reducing or avoiding the decrease in the wall adhesion of the oblique opening portion 11 during the stent retrieval process due to the action of the tensile force, and at the same time, when the outer diameter of the retrieval device 10 is reduced to reduce the stimulation of the retrieval device 10 to the blood vessel with a small inner diameter, the oblique opening portion 11 can be in close contact with the inner wall of the blood vessel. In addition, since the two reinforcing rods 141 are connected at the intersection, the structural stability of the most proximal mesh 12' bound by the two reinforcing rods 141 can be further improved, and the axial tensile strength of the first axial interval segment A1 can be further improved.

[0082] Fourth Embodiment

[0083] Please refer to FIG. 7, in the embodiment, the rod width of the net rods of the nearest end grid 12' (including two nearest end net rods 113' and two farthest end net rods 121') is greater than the rod width of the second net rods 131 of the second grid 13 in at least a part of the second axial interval segment A2, so that the ratio of the sum of the volumes of the two edges 113 and the plurality of first net rods 121 of the first axial interval segment A1 to the sum of the volumes of the plurality of second net rods 131 of the second axial interval segment A2 is 0.65-1, so as to increase the axial tensile strength of the first axial interval segment A1 and reduce the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2, and the ratio of the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2 is 0.65-1, which can reduce or avoid the decrease of the adhesion to the wall of the beveled opening portion 11 caused by the tensile force during the stentriever process, and when the stentriever 10 is used to remove the thrombus in a part of the blood vessel with a small inner diameter, the stimulation of the second axial interval segment A2 to the inner wall of the blood vessel can be reduced, and the beveled opening portion 11 can be kept adhered to the inner wall of the blood vessel.

[0084] In an embodiment, the rod width of the beveled opening portion 11 is greater than the rod width of the net rods 131 of the second grid 13 in at least a part of the second axial interval segment A2, so as to increase the axial tensile strength of the first axial interval segment A1 and reduce the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2.

[0085] Fifth embodiment

[0086] The difference between the embodiment and the fourth embodiment is that the rod width of the first net rods 121 of some of the first grids 12 in the plurality of first grids 12 in the first axial interval segment A1 except the nearest end grid 12' is greater than the rod width of the second net rods 131 of the second grid 13 in at least a part of the second axial interval segment A2, so as to increase the axial tensile strength of the first axial interval segment A1 and reduce the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2. The some of the first grids 12 in the first axial interval segment A1 are arranged on the same axis as the nearest end grid 12', and the some of the first grids 12 in the first axial interval segment A1 are crossed by the straight line L, which is more conducive to increasing the axial tensile strength of the first axial interval segment A1 and reducing the difference between the axial tensile strengths of the first axial interval segment A1 and the second axial interval segment A2.

[0087] The technical features of the above embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not contradict each other, they shall be considered as falling within the scope of the present disclosure.

[0088] The above merely provides the preferred embodiment of the application, and cannot allude the protection scope of the application, therefore any equivalent changes made according to the claims of the application shall be within the scope of the application.

Claims

1. A thrombectomy device, comprising: The application relates to a retrieval device, comprising: a retrieval frame, the retrieval frame comprising a proximal frame and a distal frame connected to a distal end of the proximal frame, the retrieval frame having an inner cavity extending through the proximal frame and the distal frame, the proximal frame comprising a first axial section and a second axial section connected to a distal end of the first axial section, a proximal end of the first axial section being formed with an oblique opening part communicating with the inner cavity, so that the first axial section has a pointed end structure pointing to the proximal end, the second axial section having a circular circumferential contour, a ratio of axial tensile strengths of the first axial section and the second axial section being in the range of [0.6, 1]; a pull tube connected to the pointed end structure; an inner tube slidably arranged in the pull tube, a distal end of the inner tube being connected to a distal end of the distal frame, and the inner tube being capable of sliding to the distal end relative to the pull tube to make the retrieval frame radially contract.

2. The thrombectomy device of claim 1, wherein, The oblique opening part has a proximal end and a distal end, when the retrieval frame is unfolded in a plane with a straight line connecting the distal end of the oblique opening part and the distal end of the distal frame as a shear line: the first axial section is a first mesh structure with a triangular outer contour, the proximal end being one vertex of the triangle, two edges of the triangle extending from the vertex to the distal end and forming the oblique opening part when closed; the first mesh structure comprises a plurality of first meshes surrounded by the two edges and a plurality of first mesh rods.

3. The thrombectomy device of claim 2, wherein, When the retrieval frame is unfolded in a plane with a straight line connecting the distal end of the oblique opening part and the distal end of the distal frame as a shear line: the second axial section is a second mesh structure surrounded by two radially opposite wavy lines, proximal ends of the two wavy lines being connected to distal ends of the two edges respectively, and a maximum radial distance between the two wavy lines being equal to a radial distance between the distal ends of the two edges, the second mesh structure comprising a plurality of second meshes surrounded by a plurality of second mesh rods; and the first mesh structure is provided with a reinforcing structure, a ratio of a sum of volumes of the two edges, the plurality of first mesh rods and the reinforcing structure in the first axial section to a sum of volumes of the plurality of second mesh rods in the second axial section being 0.65-1.

4. The thrombectomy device of claim 3, wherein, The plurality of first grids comprises a most proximal grid, the most proximal grid being surrounded by a portion of the two edges and two first grid bars, and a proximal vertex of the most proximal grid being the vertex of the triangle, the reinforcing structure comprising at least one reinforcing bar arranged in the most proximal grid, two ends of each of the reinforcing bars being fixedly connected to two first grid bars and two edges of the most proximal grid, respectively, when the shelf plane is unfolded with a straight line connecting the distal end of the oblique opening portion and the distal end of the distal support as a shearing line: the at least one reinforcing bar forms an included angle a with a straight line passing through the proximal end of the oblique opening portion and the distal end of the distal support, the included angle a being in the range of [0°, 90°], when the value of the included angle a is in the range of [0°, 12°), the length of the reinforcing bar is greater than or equal to 1 / 2 of the axial length of the most proximal grid; when the value of the included angle a is in the range of [12°, 74°], the minimum distance from the connection point of each of the reinforcing bars to the two first grid bars and two edges to the end of the two first grid bars and two edges is greater than or equal to 1 / 5 of the length of the first grid bar; when the value of the included angle a is in the range of (74°, 90°], the minimum distance from the connection point of each of the reinforcing bars to the two first grid bars and two edges to the end of the two first grid bars and two edges is greater than or equal to 1 / 5 of the length of the first grid bar or the edge, and the length of the reinforcing bar is greater than or equal to 1 / 2 of the width of the most proximal grid.

5. The device of claim 4, wherein the distal end of the elongate member is configured to be inserted into the lumen of the vessel. The reinforcing structure further comprises reinforcing bars arranged in at least one first grid other than the most proximal grid in the first axial interval segment, at least one reinforcing bar being arranged in each of the at least one first grid other than the most proximal grid, each of the reinforcing bars other than the most proximal grid being connected to two first grid bars of the first grid, when the shelf plane is unfolded with a straight line connecting the distal end of the oblique opening portion and the distal end of the distal support as a shearing line: each of the reinforcing bars other than the most proximal grid forms an included angle b with a straight line passing through the proximal end of the oblique opening portion and the distal end of the shelf, the included angle b being in the range of [12°, 74°], and the minimum distance between the connection point of each of the reinforcing bars other than the most proximal grid to the first grid bar and the end of the first grid bar is greater than or equal to 1 / 5 of the length of the first grid bar.

6. The thrombectomy device of claim 5, wherein, Part of the first grids other than the most proximal grid in the first axial interval segment are provided with the reinforcing bars, the part of the first grids being arranged on the same axis as the most proximal grid, and the part of the first grids being crossed by the straight line.

7. The device of claim 4, wherein the distal end of the elongated member is configured to be inserted into the patient's vasculature. The closest end grid is a quadrilateral grid, and two of the reinforcing rods are arranged in the closest end grid, two ends of each of the reinforcing rods are connected with the first net rod and the edge respectively, and the angle a formed by each of the reinforcing rods and the straight line is [12°, 74°], the minimum distance between the connecting point of each of the reinforcing rods and two of the two first net rods and two edges and the end of the two first net rods and two edges is greater than or equal to 1 / 5 of the length of the first net rod or the edge; the two reinforcing rods intersect, and the two reinforcing rods are connected at the intersection; or, The closest end grid is a quadrilateral grid, and two of the reinforcing rods are arranged in the closest end grid, one end of one of the reinforcing rods is connected with two vertices of the quadrilateral grid, and the other end of the reinforcing rod is connected with the other two vertices of the quadrilateral grid; and the angle a formed by one of the reinforcing rods and the straight line is 0°, and the angle a formed by the other reinforcing rod and the straight line is 90°, the two reinforcing rods intersect, and the two reinforcing rods are connected at the intersection.

8. The thrombectomy device of claim 2, wherein, When the distal end of the distal support and the distal end of the distal end of the inclined opening are connected by a straight line as a shear line, the second axial interval section is a second grid structure surrounded by two radially opposite wavy lines, the proximal ends of the two wavy lines are connected with the distal ends of the two edges respectively, and the maximum radial distance between the two wavy lines is equal to the radial distance between the distal ends of the two edges, and the second grid structure includes a plurality of second grids surrounded by a plurality of second net rods; The plurality of first grids includes a closest end grid surrounded by a part of the two edges and two first net rods, and the proximal vertex of the closest end grid is the vertex of the triangle, the rod width of the first net rod of the closest end grid is greater than the rod width of the second net rod of at least a part of the second grid in the second axial interval section, and the rod width of the part of the edge used to form the closest end grid is greater than the rod width of the second net rod of at least a part of the second grid in the second axial interval section. The ratio of the sum of the volumes of the two edges and the plurality of first net rods in the first axial interval section to the sum of the volumes of the plurality of second net rods in the second axial interval section is 0.65-1.

9. The device of claim 8, wherein the distal end of the elongated member is configured to be inserted into the lumen of the blood clot. The rod width of the first net rod of a part of the first grid in the first axial interval section is greater than the rod width of the second net rod of at least a part of the second grid in the second axial interval section, the part of the first grid is arranged on the same axis as the closest end grid, and the part of the first grid in the first axial interval section is crossed by a straight line passing through the proximal end of the inclined opening and the distal end of the distal support.

10. The device according to claim 8 or 9, characterized in that The first grid structure is provided with a reinforcing structure, the reinforcing structure includes at least one reinforcing rod arranged in the nearest end grid, two ends of each of the reinforcing rods are fixedly connected with two of the two first grid rods and two edges of the nearest end grid, when the plane of the retrieval rack is unfolded along a straight line connecting the distal end of the oblique opening part and the distal end of the distal end support as a shear line: the at least one reinforcing rod forms an included angle a with a straight line passing through the proximal end of the oblique opening part and the distal end of the distal end support, the included angle a ranges from [0°, 90°], when the value of the included angle a is in the range of [0°, 12°), the length of the reinforcing rod is greater than or equal to 1 / 2 of the axial length of the nearest end grid; when the value of the included angle a is in the range of [12°, 74°], the minimum distance from the connection point of each of the reinforcing rods to the two of the two first grid rods and two edges to the end of the two of the two first grid rods and two edges is greater than or equal to 1 / 5 of the length of the first grid rod or the edge; when the value of the included angle a is in the range of (74°, 90°], the minimum distance from the connection point of each of the reinforcing rods to the two of the two first grid rods and two edges to the end of the two of the two first grid rods and two edges is greater than or equal to 1 / 5 of the length of the first grid rod, and the length of the reinforcing rod is greater than or equal to 1 / 2 of the width of the nearest end grid.

11. The device of claim 10, wherein the distal end of the elongated member is configured to be inserted into the lumen of the blood clot. The reinforcing structure further includes reinforcing rods in at least one first grid other than the nearest end grid within the first axial interval segment, at least one reinforcing rod is arranged in each of the at least one first grid other than the nearest end grid, each of the reinforcing rods located outside the nearest end grid is connected with two first grid rods of the first grid, when the plane of the retrieval rack is unfolded along a straight line connecting the distal end of the oblique opening part and the distal end of the distal end support as a shear line: each of the reinforcing rods located outside the nearest end grid forms an included angle b with a straight line passing through the proximal end of the oblique opening part and the distal end of the retrieval rack, the included angle b ranges from [12°, 74°], and the minimum distance between the connection point of each of the reinforcing rods located outside the nearest end grid to the end of the first grid rod is greater than or equal to 1 / 5 of the length of the first grid rod.

12. The thrombectomy device of claim 8, wherein, The rod width of the edge is greater than the rod width of the second grid rod of at least a part of the second grid within the second axial interval segment.

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