Prosthetic venous valve, stent, and prosthetic venous valve leaflet and design method therefor

Abstract

Provided in the present disclosure are a prosthetic venous valve, a stent, and a prosthetic venous valve leaflet and a design method therefor, relating to the technical field of medical instruments. The stent involved in the present disclosure comprises a proximal segment support frame, a valve leaflet fixing assembly, a pocket-shaped support rod, and a distal segment support frame. The valve leaflet fixing assembly is connected between the proximal segment support frame and the distal segment support frame, and is configured for fixing the valve leaflet. A first end of the pocket-shaped support rod is connected to the proximal segment support frame, and a second end of the pocket-shaped support rod is connected to the distal segment support frame. When the stent is expanded, the pocket-shaped support rod can protrude along a radial direction of the stent in a direction away from the central axis of the stent, so as to form a pocket-shaped space on a proximal side of the valve leaflet fixing assembly.

Description

An artificial venous valve, a stent, artificial venous valve leaflets, and their design method.

[0001] Cross-references

[0002] This application claims priority to Chinese application 202410792851.8, filed on June 19, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This specification relates to the field of medical device technology, and in particular to an artificial venous valve and its stent. Background Technology

[0004] Veins are responsible for carrying blood from all parts of the body back to the heart. To prevent backflow, veins contain valves. When blood flows towards the heart, the valves open, allowing blood to flow in; after the blood has flowed out, the valves close. Venous valves are "one-way valves" that ensure the return of blood from veins to the heart. Damage or disease of venous valves can cause venous blood to reflux, leading to venous hypertension and subsequently chronic venous disease (CVD).

[0005] Some scientists have proposed creating artificial venous valves to replace diseased venous valves. Artificial venous valves can be implanted into target locations within veins (such as damaged or diseased native venous valves), thereby replacing the native valves and preventing blood reflux.

[0006] Some embodiments in this specification are intended to provide an artificial venous valve and its stent that are structurally more stable and better adapted to the intravascular environment of veins.

[0007] Summary of the Invention

[0008] This specification provides one or more embodiments of a stent for use in an artificial venous valve, including a proximal support frame, a leaflet fixation assembly, a pocket-shaped support rod, and a distal support frame; the leaflet fixation assembly is connected between the proximal and distal support frames and is used to fix the leaflets; a first end of the pocket-shaped support rod is connected to the proximal support frame, and a second end is connected to the distal support frame; when the stent is opened, the pocket-shaped support rod can protrude radially away from the central axis of the stent to form a pocket-shaped space on the proximal side of the leaflet fixation assembly.

[0009] According to some embodiments of the bracket described in this specification, the pocket-shaped support rod includes one or more S-shaped portions connected in sequence, wherein the opening of at least one half-arc of at least one S-shaped portion is greater than 0, and the opening of the half-arc is positively correlated with the angle between the tangents at the two endpoints of the half-arc.

[0010] According to some embodiments of the bracket described in this specification, the number of pocket-shaped support rods is two or more; the proximal end support frame includes two or more V-shaped support legs respectively connected to the two or more pocket-shaped support rods; when the bracket is opened, the V-shaped opening of the V-shaped support leg is greater than a set threshold, and the V-shaped opening is positively correlated with the included angle between the two sides forming the V-shaped structure; the first end of the pocket-shaped support rod is connected to the corresponding V-shaped support leg.

[0011] According to some embodiments of the bracket described in this specification, when the bracket is opened, the height of the point on the pocket-shaped support rod that is furthest from the central axis of the bracket along the radial direction of the bracket is related to the V-shaped opening and / or length of the V-shaped support foot.

[0012] According to some embodiments of the bracket described in this specification, when the bracket is opened, the length of the V-shaped support leg is less than the total length of the one or more S-shaped portions connected in sequence in the pocket-shaped support rod.

[0013] According to some embodiments of the bracket described in this specification, the S-shaped portion near the distal segment of the support frame in the pocket-shaped support rod is a straight rod between the second end of the pocket-shaped support rod; the total length of the one or more S-shaped portions connected in sequence in the pocket-shaped support rod is greater than the length of the straight rod.

[0014] According to some embodiments of the bracket described in this specification, in one or more S-shaped portions connected sequentially in the pocket-shaped support rod, the opening of the semi-circle near the distal segment support frame is greater than the opening of the semi-circle near the proximal segment support frame.

[0015] According to some embodiments of the stent described in this specification, the leaflet fixation assembly includes two curved rods connected in a V-shape; the connection point of the two curved rods is connected to the distal segment support frame, and the outer endpoints of the two curved rods, respectively away from the connection point, are connected to the proximal segment support frame.

[0016] According to some embodiments of the bracket described in this specification, the orthographic projection of one or more of the pocket-shaped support rods onto the bracket's axial section lies between the orthographic projections of the two curved rods in the leaflet fixing assembly onto the bracket's axial section.

[0017] According to some embodiments of the bracket described in this specification, the number of the pocket-shaped support rod and the number of the leaflet fixing components are both 2; the two leaflet fixing components are arranged opposite to each other in the circumferential direction of the bracket; the orthographic projection of the first pocket-shaped support rod on the axial section of the bracket is located in the middle of the orthographic projection of the two curved rods in the first leaflet fixing component on the axial section of the bracket, and the orthographic projection of the second pocket-shaped support rod on the axial section of the bracket is located in the middle of the orthographic projection of the two curved rods in the second leaflet fixing component on the axial section of the bracket.

[0018] According to some embodiments of the bracket described in this specification, the curved rod has two or more arcuate portions; a reference plane is determined based on the connection point of the two curved rods in the leaflet fixing assembly and the outer endpoints of the two curved rods, and the two or more arcuate portions of the curved rods of the leaflet fixing assembly are distributed on different sides of the reference plane.

[0019] According to some embodiments of the bracket described in this specification, among the two or more arcuate portions of the curved rod, the arcuate portion closer to the distal segment support frame is located on the proximal side of the corresponding reference plane.

[0020] According to some embodiments of the bracket described in this specification, the curved rod has two arc-shaped portions, the arc-shaped portion closer to the distal segment support frame located on the proximal side of the corresponding reference plane, and the arc-shaped portion farther from the distal segment support frame located on the distal side of the reference plane.

[0021] According to some embodiments of the stent described in this specification, the proximal support frame includes two or more proximal support grids; the outer ends of the two cranks in the leaflet fixing assembly are respectively connected to different proximal support grids.

[0022] According to some embodiments of the stent described in this specification, the number of the proximal support grid and the number of the leaflet fixing components are both 2; the two leaflet fixing components are arranged opposite to each other in the circumferential direction of the stent; the outer end point of one of the curved rods in the first leaflet fixing component and the outer end point of one of the curved rods in the second leaflet fixing component are both connected to the first positioning ear, and the first positioning ear is connected to the first proximal support grid; the outer end point of the other curved rod in the first leaflet fixing component and the outer end point of the other curved rod in the second leaflet fixing component are both connected to the second positioning ear, and the second positioning ear is connected to the second proximal support grid.

[0023] According to some embodiments of the bracket described in this specification, the first positioning ear and the second positioning ear are respectively provided with two positioning holes distributed along the axial direction of the bracket, and the positioning holes are used to fix the leaflets.

[0024] According to some embodiments of the stent described in this specification, the proximal support grid has a V-shaped frame, wherein the V-shaped frame includes one or more triangular sub-grids and / or one or more quadrilateral sub-grids.

[0025] According to some embodiments of the bracket described in this specification, the V-shaped opening of the V-shaped frame is less than or equal to a set threshold, and the V-shaped opening is positively correlated with the included angle between the two sides forming the V-shaped structure.

[0026] According to some embodiments of the bracket described in this specification, when the bracket is extended, the point on the pocket-shaped support rod that is furthest from the central axis of the bracket along the radial direction of the bracket is at the same height as the connection point between the outer end of the curved rod and the proximal support grid in the leaflet fixing assembly in the axial direction of the bracket; or, when the bracket is extended, the point on the pocket-shaped support rod that is furthest from the central axis of the bracket along the radial direction of the bracket is closer to the distal support frame in the axial direction of the bracket than the connection point between the outer end of the curved rod and the proximal support grid in the leaflet fixing assembly.

[0027] According to some embodiments of this specification, the distal segment support frame includes a first distal segment support grid and a second distal segment support grid; the first distal segment support grid is arranged below one of the curved rods in the first leaflet fixing assembly and one of the curved rods in the second leaflet fixing assembly; the second distal segment support grid is arranged below the other curved rod in the first leaflet fixing assembly and the other curved rod in the second leaflet fixing assembly; a barrier membrane is fixed on the first distal segment support grid and the second distal segment support grid respectively, and the material of the barrier membrane includes polymer materials and / or bio-derived materials.

[0028] According to some embodiments of the support described in this specification, the first distal segment support grid has a first W-shaped frame, and the second distal segment support grid has a second W-shaped frame; the connection point of the two curved rods in the first leaflet fixing assembly is connected to one end of the first W-shaped frame and one end of the second W-shaped frame respectively through a first positioning rod; the connection point of the two curved rods in the second leaflet fixing assembly is connected to the other end of the first W-shaped frame and the other end of the second W-shaped frame respectively through a second positioning rod; the W-shaped frame includes one or more triangular sub-grids and / or one or more quadrilateral sub-grids.

[0029] According to some embodiments of the bracket described in this specification, the proximal support frame is an inverted truncated pyramid, and the distal support frame is a normal truncated pyramid. The maximum radial dimension of the upper base of the inverted truncated pyramid is greater than the maximum radial dimension of the lower base, and the maximum radial dimension of the upper base of the normal truncated pyramid is less than the maximum radial dimension of the lower base.

[0030] According to some embodiments of the bracket described in this specification, the minimum upper bottom angle of the inverted platform is smaller than the minimum lower bottom angle of the upright platform.

[0031] According to some embodiments of the bracket described in this specification, the minimum upper bottom angle of the inverted platform is taken from the numerical range of 75° to 85°, and the minimum lower bottom angle of the upright platform is taken from the numerical range of 80° to 87°.

[0032] According to some embodiments of this specification, the number of leaflet fixing components is 1, and the support also includes a fixing accessory; the fixing accessory is connected between the proximal support frame and the distal support frame, and is disposed opposite to the leaflet fixing components in the circumferential direction of the support.

[0033] According to some embodiments of the stent described in this specification, the leaflet fixation assembly includes two curved rods connected in a V-shape; the connection point of the two curved rods is connected to the distal segment support frame, and the outer endpoints of the two curved rods, respectively away from the connection point, are connected to the proximal segment support frame; the fixing accessory has the same structure as the leaflet fixation assembly.

[0034] According to some embodiments of the bracket described in this specification, the orthographic projection of the pocket-shaped support rod on the bracket's axial section is located between the orthographic projections of the two curved rods in the leaflet fixing assembly on the bracket's axial section.

[0035] According to some embodiments of the stent described in this specification, the radial dimension of the rod constituting the leaflet fixation assembly is greater than the radial dimension of the rod constituting the remaining parts of the stent, so that when the stent is expanded in the blood vessel, the contact surface between the rod constituting the leaflet fixation assembly and the blood vessel per unit length is greater than the contact surface between the rod constituting the remaining parts and the blood vessel per unit length; the remaining parts include one or more of the following parts: the proximal support frame, the pocket-shaped support rod, and the distal support frame.

[0036] According to some embodiments of the bracket described in this specification, the radial dimension of the rod constituting the leaflet fixing assembly is n times the radial dimension of the rod constituting the remaining parts, where 1 < n ≤ 2.

[0037] According to some embodiments of the bracket described in this specification, the radial dimension of the rod constituting the leaflet fixing assembly is 0.1 mm to 0.5 mm.

[0038] One or more embodiments of this specification also provide an artificial venous valve, including an artificial venous valve leaflet and a stent as described above; the artificial venous valve leaflet is fixedly disposed on the leaflet fixing assembly.

[0039] According to some embodiments of the artificial venous valve described in this specification, the artificial venous valve leaflet has a fixed side, which is fixed to two curved rods connected in a V-shape in the leaflet fixing assembly; the artificial venous valve leaflet also has a free side, which is located between the two ends of the fixed side of the leaflet.

[0040] According to some embodiments of the artificial venous valve described in this specification, the artificial venous valve leaflet further has a first leaflet auricle, a second leaflet auricle, and a positioning part; the first leaflet auricle and the second leaflet auricle of the artificial venous valve leaflet are respectively fixed at the first positioning auricle and the second positioning auricle, and the positioning part of the artificial venous valve leaflet is fixed at the positioning rod connected to the connection point of the two curved rods in the corresponding leaflet fixing assembly.

[0041] According to some embodiments of the artificial venous valve described in this specification, the free edge of the artificial venous valve leaflet is an arcuate edge convex toward its fixed edge.

[0042] According to some embodiments of the artificial venous valve described in this specification, the fixed edge and the free edge form a boundary, within which a leaflet surface is defined; the free edge is configured to cooperate with a mating portion to achieve opening and closing; the leaflet surface is configured such that its projection on at least one axial section of the vein is a spline curve, the spline curve having at least a main body portion; a coordinate system is established with the center of the radial plane of the vein where the artificial venous valve leaflet is located as the origin, the projection direction of the projection as the y-axis direction, the axial direction of the vein as the z-axis direction, and the direction orthogonal to the y-axis and z-axis as the x-axis direction, in which the slope of the tangent at any point on the main body portion of the spline curve is a non-positive or non-negative value.

[0043] According to some embodiments of the artificial venous valve described in this specification, the spline curve further includes a starting portion and / or an ending portion connected to the main body portion, the starting portion and / or the ending portion being parallel to the z-axis direction.

[0044] According to some embodiments of the artificial venous valve described in this specification, the main body of the spline curve sequentially includes: a first segment extending along the axial direction of the vein, a second segment bending outward toward the radial direction of the vein, and a third segment bending toward the axial direction of the vein.

[0045] According to some embodiments of the artificial venous valve described in this specification, the fixed edge is a spatial curve, and the fixed edge is located on the side of a cylinder.

[0046] According to some embodiments of the artificial venous valve described in this specification, the diameter of the cylinder ranges from 2 to 15 mm, and the height of the cylinder ranges from 2 to 20 mm.

[0047] According to some embodiments of the artificial venous valve described in this specification, the first straight line formed by the proximal endpoint of the spline curve moving along the projection direction has a gap with the axis of the cylinder.

[0048] According to some embodiments of the artificial venous valve described in this specification, the spacing ranges from 0 to 1 mm.

[0049] According to some embodiments of the artificial venous valve described in this specification, the value of the projected height of the arcuate edge on the axial section of the vein ranges from 0 to 10 mm, or the value of the projected height of the arcuate edge on the axial section of the vein is 0 to 2 / 3 times the value of the projected height of the artificial venous valve leaflet on the axial section of the vein.

[0050] According to some embodiments of the artificial venous valve described in this specification, the mating part is: the free edge of another artificial venous valve leaflet, or a second stent, or the inner wall of the vein.

[0051] According to some embodiments of the artificial venous valve described in this specification, the leaflet surface includes a first arc-shaped surface and a second arc-shaped surface with opposite convex directions. The first arc-shaped surface is closer to the proximal end than the second arc-shaped surface. The first arc-shaped surface convexes towards the distal end, and the second arc-shaped surface convexes towards the proximal end.

[0052] According to some embodiments of the artificial venous valve described in this specification, the leaflet surface is configured to form a pocket-shaped space between the leaflet and the venous wall on the proximal side.

[0053] One or more embodiments of this specification also provide an artificial venous valve leaflet, comprising: a free edge, a fixed edge whose two ends are respectively connected to the two ends of the free edge to form a boundary, and a leaflet surface defined within the boundary; the fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein; the free edge is configured to cooperate with a mating portion to achieve opening and closing; the leaflet surface is configured such that its projection on at least one axial section of the vein is a spline curve, the spline curve including at least a main body portion; a coordinate system is established with the center of the radial plane of the vein where the artificial venous valve leaflet is located as the origin, the projection direction of the projection as the y-axis direction, the axial direction of the vein as the z-axis direction, and the direction orthogonal to the y-axis and z-axis as the x-axis direction, in which the slope of the tangent at any point on the main body portion of the spline curve is a non-positive or non-negative value.

[0054] According to some embodiments of the artificial venous valve described in this specification, the spline curve further includes a starting portion and / or an ending portion connected to the main body portion, the starting portion and / or the ending portion being parallel to the z-axis direction.

[0055] According to some embodiments of the artificial venous valve described in this specification, the main body of the spline curve sequentially includes: a first segment extending along the axial direction of the vein, a second segment bending outward toward the radial direction of the vein, and a third segment bending toward the axial direction of the vein.

[0056] According to some embodiments of the artificial venous valve described in this specification, the fixed edge is a spatial curve, and the fixed edge is located on the side of a cylinder.

[0057] According to some embodiments of the artificial venous valve described in this specification, the diameter of the cylinder ranges from 2 to 15 mm, and the height of the cylinder ranges from 2 to 20 mm.

[0058] According to some embodiments of the artificial venous valve described in this specification, the first straight line formed by the proximal endpoint of the spline curve moving along the projection direction has a gap with the axis of the cylinder.

[0059] According to some embodiments of the artificial venous valve described in this specification, the spacing ranges from 0 to 1 mm.

[0060] According to some embodiments of the artificial venous valve described in this specification, the free edge is an arcuate edge convex toward its fixed edge.

[0061] According to some embodiments of the artificial venous valve leaflet described in this specification, the value of the projected height of the arcuate edge on the axial section of the vein ranges from 0 to 10 mm, or the value of the projected height of the arcuate edge on the axial section of the vein is 0 to 2 / 3 times the value of the projected height of the artificial venous valve leaflet on the axial section of the vein.

[0062] According to some embodiments of this specification, the mating part of the artificial venous valve leaflet is: the free edge of another artificial venous valve leaflet, or a second stent, or the inner wall of the vein.

[0063] According to some embodiments of this specification, the artificial venous valve leaflet includes a first arcuate surface and a second arcuate surface with opposite convex directions. The first arcuate surface is closer to the proximal end than the second arcuate surface. The first arcuate surface convexes towards the distal end, and the second arcuate surface convexes towards the proximal end.

[0064] According to some embodiments of the artificial venous valve described in this specification, the leaflet surface is configured to form a pocket-shaped space between the leaflet and the venous wall on the proximal side.

[0065] This specification also provides a method for designing an artificial venous valve leaflet, the artificial venous valve leaflet comprising: a free edge, a fixed edge whose two ends are respectively connected to the two ends of the free edge to form a boundary, and a leaflet surface defined within the boundary; the fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein; the free edge is configured to cooperate with a mating portion to achieve opening and closing; the design method comprising: providing a spline curve; sweeping a sweep line along the spline curve to obtain a first surface; providing a cut cylinder such that the sweep line passing through the proximal endpoint of the spline curve is coplanar with a radial plane of the cut cylinder, such that the first surface intersects the side surface of the cut cylinder; removing the portion of the first surface located outside the cut cylinder to obtain a second surface, wherein the fixed edge is formed at the cut portion of the second surface by the cut cylinder; wherein the leaflet surface is located within the second surface.

[0066] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, a trimming curve is provided, and the edges of the second surface other than the fixed edge are trimmed according to the trimming curve to form the free edge.

[0067] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, when the fixing edge is configured to be directly or indirectly fixed to the inner wall of the vein and the second curved surface bulges toward the distal end, there is an overlapping area between the second curved surface and the mating portion, and the cutting curve is determined based on the edge of the overlapping area or is located within the overlapping area.

[0068] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, the cutting curve is configured such that when the fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein and the second curved surface bulges toward the distal end, the free edge formed by the cutting curve remains in contact with the mating portion.

[0069] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, the method of providing the cutting curve includes: determining the mating portion; establishing a model such that the fixed edge of the second curved surface fits into the vein, and the edges of the second curved surface other than the fixed edge fit into the mating portion; forming a sealing line or sealing surface between the second curved surface and the mating portion; the cutting curve is the sealing line, or the cutting curve is located within the sealing surface.

[0070] According to the design method of the artificial venous valve leaflet described in some embodiments of this specification, the mating part is a second artificial venous valve leaflet identical to the artificial venous valve leaflet; the method of providing the cutting curve includes: establishing a model, arranging the artificial venous valve leaflet and the second artificial venous valve leaflet opposite to a certain axial section of the vein, such that the fixed edge of the second curved surface of the artificial venous valve leaflet and the fixed edge of the second curved surface of the second artificial venous valve leaflet respectively fit against the inner wall of the vein; forming a sealing line or sealing surface between the two second curved surfaces; the cutting curve is the sealing line, or the cutting curve is located within the sealing surface.

[0071] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, the fixed side extends outward on both sides near the free side to form a first leaflet ear and a second leaflet ear, respectively.

[0072] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, the fixed edge extends outward from the free edge to form a positioning part.

[0073] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, the spline curve has at least a main body portion; a coordinate system is established with the center of the diameter plane of the vein where the artificial venous valve leaflet is located as the origin, the direction of the sweep line passing through the proximal endpoint of the spline curve as the y-axis direction, the axial direction of the vein as the z-axis direction, and the direction orthogonal to the y-axis and z-axis as the x-axis direction. In this coordinate system, the slope of the tangent at any point on the main body portion of the spline curve is a non-positive or non-negative value.

[0074] According to the design method of artificial venous valve leaflets described in some embodiments of this specification, the spline curve further includes a starting portion and / or an ending portion connected to the main body portion, wherein the starting portion and / or ending portion is parallel to the z-axis direction.

[0075] One or more embodiments of this specification also provide an artificial venous valve leaflet, obtained by the above-described artificial venous valve leaflet design method.

[0076] One or more embodiments of this specification also provide an artificial venous valve leaflet assembly, comprising two mirror-arranged artificial venous valve leaflets, wherein the artificial venous valve leaflets are those described above; wherein the free edges of the two artificial venous valve leaflets are operably fitted together. Attached Figure Description

[0077] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. The same numbers in the drawings denote the same structures or steps.

[0078] Figure 1 is a perspective view of an artificial venous valve according to some embodiments of this specification.

[0079] Figure 2 shows a cut mesh surface of a bracket according to some embodiments of this specification.

[0080] Figure 3 is a first side view of the bracket shown according to some embodiments of this specification.

[0081] Figure 4 is a second side view of the bracket shown according to some embodiments of this specification.

[0082] Figure 5 is a structural schematic diagram of the S-shaped part according to some embodiments of this specification.

[0083] Figure 6 is a structural schematic diagram of the V-shaped support foot and the pocket-shaped support rod according to some embodiments of this specification.

[0084] Figure 7 is a side view of Figure 6.

[0085] Figure 8 is a structural schematic diagram of a leaflet fixing assembly according to some embodiments of this specification.

[0086] Figure 9 is a schematic diagram of the structure of the crank in the leaflet fixing assembly according to some embodiments of this specification.

[0087] Figure 10 is a first side view of a proximal support frame according to some embodiments of this specification.

[0088] Figure 11 is a second side view of a proximal support frame according to some embodiments of this specification.

[0089] Figure 12 is a first side view of a distal segment support frame according to some embodiments of this specification.

[0090] Figure 13 is a second side view of the distal segment support frame according to some embodiments of this specification.

[0091] Figure 14 is a second side view of the bracket according to some other embodiments of this specification.

[0092] Figure 15 is a side profile view of the bracket according to some embodiments of this specification.

[0093] Figure 16 shows a cut mesh surface of a bracket according to some other embodiments of this specification.

[0094] Figure 17 is a schematic diagram of a leaflet according to some embodiments of this specification.

[0095] Figure 18 is a first-state diagram of an artificial venous valve in a venous vessel according to some embodiments of this specification.

[0096] Figure 19 is a second-state diagram of an artificial venous valve in a venous vessel, according to some embodiments of this specification.

[0097] Figures 20 to 22 are diagrams showing different states of the leaflets according to some embodiments of this specification.

[0098] Figure 23 is a structural schematic diagram of an artificial venous valve according to some other embodiments of this specification.

[0099] Figure 24 is a diagram showing the state of the artificial venous valve in the vein as shown in Figure 23.

[0100] Figure 25 is a schematic diagram of spline curves according to some embodiments of this specification.

[0101] Figure 26 is a schematic diagram of a spline curve and a first surface according to some embodiments of this specification.

[0102] Figure 27 is a schematic diagram showing a first curved surface cut by a cylinder or a cut cylinder according to some embodiments of this specification.

[0103] Figure 28 is a schematic diagram showing the positional relationship between a first straight line and a cylinder or a cut cylinder according to some embodiments of this specification.

[0104] Figure 29 is a schematic diagram of the dimensions of a cylinder or cut cylinder according to some embodiments of this specification.

[0105] Figure 30 is a schematic diagram of a leaflet surface according to some embodiments of this specification.

[0106] Figures 31 and 32 are schematic diagrams of overlapping areas shown in some embodiments according to this specification.

[0107] Figure 33 is a schematic diagram illustrating the cutting based on a cutting curve according to some embodiments of this specification.

[0108] Figure 34 is a schematic diagram of the valve opening state according to some embodiments of this specification.

[0109] Figure 35 is a reference comparison diagram of non-monotonic spline curves according to this specification.

[0110] In the diagram, the markings are: 1. Proximal support frame; 11. V-shaped support foot; 12. Proximal support grid; 121. V-shaped frame; 122. Support rod; 2. Leaflet fixing assembly; 21, 22. Curved rods; 211, 212. Arc-shaped parts; 23, 24. External connection points; 25. Connection point; 3. Pocket-shaped support rod; 31. S-shaped part; 32. Straight rod; 33. Farthest point; 4. Telecentric support frame; 41. Telecentric support grid; 411. W-shaped frame; 412. Support rod; 5. Leaflet; 51. Fixed edge; 52. Free edge; 53. First leaflet ear; 54. Second leaflet ear; 55. Positioning part; 56. Leaflet Interval opening; 57 Leaflet fitting area; 5a Second artificial venous valve leaflet; 6 Positioning ear; 61 Positioning hole; 7 Positioning rod; 8 Barrier membrane; 9 Leaflet curved surface; 91 Spline curve; 911 First segment; 912 Second segment; 913 Third segment; o Endpoint; A First curved surface; B Second curved surface; C Overlapping area; 92 Cylinder; d3 Diameter of cylinder; h1 Height of cylinder; h2 Projected height of arc edge on the axial section of vein; h3 Projected height of leaflet on the axial section of vein; l1 First straight line; D1 Distance between the first straight line and the axis of cylinder; l s Sweep line; l c Trim curves. Detailed Implementation

[0111] To more clearly illustrate the technical solutions of the embodiments in this specification, the embodiments will be described in detail below with reference to the accompanying drawings. Obviously, the content described below are some examples or embodiments of this specification. For those skilled in the art, without creative effort, the technical solutions or means disclosed in this specification can be applied to other scenarios based on this technical content.

[0112] Unless otherwise specified, the technical terms used to describe components, elements, etc. in this specification are not singular but may include plural. Generally speaking, terms such as "comprising" or "including" only indicate that explicitly identified steps, elements, or components are included, and these steps, elements, and components do not constitute an exclusive list, as the described method or apparatus may also include other steps or components.

[0113] Artificial venous valves (hereinafter referred to as artificial valves) generally consist of a stent and leaflets, with the leaflets fixed to the stent. The stent needs to provide good support to ensure that the leaflets are effectively fixed in the blood vessel. Its materials can include metals, polymers, and biomaterials, with metals including tantalum, medical-grade stainless steel, and nickel-titanium alloys. The stent can have a folded-up state and an expanded state. Before implantation into a vein, the stent is in the folded-up state to compress into the sheath of the catheter. The artificial venous valve is then inserted into the vein through the catheter. When it reaches the target implantation location, the stent expands, and thereafter the artificial venous valve supports the blood vessel at the target implantation location and functions in place of the native venous valve. In some embodiments, when the stent expands, the proximal side of the leaflet (i.e., the side of the leaflet facing the heart after implantation into the vein) can form a pocket-shaped space (or, in other words, the stent bulges radially away from the center of the blood vessel). This allows blood flow to bypass the pocket-shaped space, preventing venous blood from stagnating and forming thrombi in the angled area between the leaflet and the vessel wall. To facilitate proper expansion of the stent within the blood vessel, the stent material needs to possess a certain degree of elasticity or flexibility. Therefore, how to enable the stent to simultaneously possess good support and flexibility is a problem worthy of research.

[0114] Therefore, some embodiments of this specification propose a support that, through structural improvements, effectively meets both the requirements for support and deformation.

[0115] It should be noted that, unless otherwise specified, the structural features of the bracket described in some embodiments of this specification are applicable to both the supported state and the retracted state.

[0116] Figure 1 is a perspective view of an artificial venous valve according to some embodiments of this specification, showing the structural morphology of the artificial venous valve when the stent is expanded. As shown in Figure 1, the artificial venous valve stent and leaflet 5 provided in some embodiments of this specification, wherein the stent further includes a proximal support frame 1, a leaflet fixing component 2, a pocket-shaped support rod 3, and a distal support frame 4. The proximal segment refers to the section of the stent closest to the heart after the artificial valve is implanted into a vein, while the distal segment is the section furthest from the heart. The leaflet fixing component 2 is connected between the proximal support frame 1 and the distal support frame 4 to fix the leaflet. The pocket-shaped support rod 3 is arranged along the axial direction of the stent, with its first end connected to the proximal support frame 1 and its second end connected to the distal support frame 4. To facilitate differentiation of the different components of the stent from the figure, dashed lines are used in Figure 1 to indicate the connection points between the proximal support frame 1 and the leaflet fixing component 2 and the pocket-shaped support rod 3, and double-dotted lines are used to indicate some connections between the distal support frame 1 and the leaflet fixing component 2 and the pocket-shaped support rod 3. The artificial venous valve shown in Figure 1 has a double-leaf symmetrical design for its leaflet 5. When the artificial venous valve is inserted into the blood vessel, the stent is wrapped around the blood vessel wall in the circumferential direction, and the two leaflets 5 form a one-way valve in the axial direction of the blood vessel, which opens and closes periodically with the blood flow.

[0117] In some embodiments, the stent can be formed by laser cutting of tubing made of a suitable material. As an example, a structural "pattern" of the stent can be designed on a computer device, and then cut onto the tubing using laser printing technology to obtain a stent in a folded state. Figure 2 shows a cut grid of the stent according to some embodiments of this specification. The cut tubing can be longitudinally cut and flattened to obtain the state shown in Figure 2. Similar to Figure 1, Figure 2 uses dashed lines to illustrate the connection between the proximal support frame 1 and the leaflet fixing assembly 2 and the pocket-shaped support rod 3, and uses double-dotted lines to illustrate the connection between the distal support frame 1 and the leaflet fixing assembly 2 and the pocket-shaped support rod 3. By arranging the cut grid shown in Figure 2 into a column shape with the vertical axis as the central axis, the aforementioned folded stent can be obtained.

[0118] Comparing Figures 1 and 2, it can be seen that when the stent is deployed, the pocket-shaped support rod 3 protrudes radially away from the central axis of the stent, forming a pocket-shaped space on the proximal side of the leaflet fixing assembly 2 (or leaflet 5). After the artificial venous valve is implanted into the blood vessel, on the one hand, blood flow can form a bypass flow in the pocket-shaped space, preventing venous blood from stagnating and forming thrombi in the angle area between the leaflet and the blood vessel wall; however, on the other hand, the stent will be subjected to axial force due to the impact of blood flow, and at the same time, due to the radial pressure from the blood vessel wall, the pocket-shaped support rod may become unstable, and then bulge radially towards the central axis of the stent (such as folding inward), ultimately leading to the failure of the artificial valve.

[0119] Figure 3 is a first side view of a stent according to some embodiments of this specification. In some embodiments, the pocket-shaped support rod 3 may include one or more S-shaped portions 31 and straight rods 32 connected in sequence. The S-shaped portion 31 has a larger lateral width than the straight rod 32, which can improve the instability stress threshold to a certain extent and reduce the probability of instability of the pocket-shaped support rod. As an example, the diameter of the straight rod 32 in the pocket-shaped support rod 3 can be 0.3 to 0.5 mm, and the lateral width of the formed S-shaped portion 31 (width D as shown in Figure 6) can reach 1 to 2 mm. It can be seen that the lateral dimension of the pocket-shaped support rod 3 can be effectively increased by the S-shaped portion 31. The S-shaped portion 31 can also increase the contact area between the stent and the blood vessel, preventing the artificial valve from shifting under blood pressure.

[0120] In some embodiments, the opening of at least one half-arc of at least one S-shaped portion is greater than 0. As shown in FIG. 5, the half-arc can be the upper or lower half of the S-shape. A half-arc can be considered as a shape composed of two straight lines and the arc between them. The opening of the half-arc is positively correlated with the angle between the tangents at the two endpoints of the half-arc. For example, the opening of the half-arc can be related to the size of the angle θ in FIG. 5. An opening of the half-arc greater than 0 means that its two straight lines are not parallel. The larger the opening of the half-arc, the greater the rigidity of the S-shaped portion, and the smaller the probability of the pocket support rod 3 becoming unstable. Therefore, the local stiffness of the pocket support rod can be adjusted by changing the opening of the half-arc of the S-shaped portion. In some embodiments, the opening of the half-arc can be taken from the numerical range [15°, 20°]. In some embodiments, all half-arcs in one or more S-shaped portions 31 connected in sequence have equal openings, as shown on the left side of FIG. 5. In other embodiments, different semi-circles in one or more S-shaped sections 31 connected in sequence can have different openings, as shown on the right side of FIG5. The opening of the upper semi-circle in one or more S-shaped sections 31 can be characterized by angle θ1, and the opening of the lower semi-circle can be characterized by angle θ2, wherein angle θ1 is smaller than angle θ2. Specifically, the opening of the semi-circle near the distal segment support 4 in the stent is greater than the opening of the semi-circle near the proximal segment support 1. In this way, when the stent is opened, the part of the pocket-shaped support rod 3 near the distal segment support 4 has greater strength. Even if the part near the proximal end support 1 experiences a certain degree of instability and inward folding, the stent can still form a larger pocket-shaped space in the area near the proximal side of the leaflet 5, ensuring that blood can form turbulence, thereby reliably reducing the probability of thrombus formation.

[0121] In some embodiments, one or more S-shaped portions 31 connected in sequence may include an even number of semi-circles, such as 2, 4, etc. In other embodiments, one or more S-shaped portions 31 connected in sequence may also include an odd number of semi-circles, such as 3, 5, etc.

[0122] Figure 10 is a first side view of the proximal support frame according to some embodiments of this specification. Referring to Figures 3 and 10, in some embodiments, the proximal support frame 1 includes V-shaped support legs 11 connected to corresponding pocket-shaped support rods 3. Specifically, the V-shaped support legs 11 can correspond one-to-one with the pocket-shaped support rods 3. Referring to Figure 2, in the cut mesh surface, the V-shaped support legs 11 converge to form two approximately parallel sides. When the support frame is opened, the V-shaped support legs 11 are opened in a V-shape. By adjusting the dimensions of each part of the proximal support frame 1, the V-shaped opening of the V-shaped support legs 11 when the support frame is opened can be adjusted, wherein the V-shaped opening is positively correlated with the included angle between the two sides forming the V-shaped structure. As shown in Figures 2 and 3, the first end (specifically the proximal end) of the pocket-shaped support rod 3 is connected to the corresponding V-shaped support leg 11 of the proximal support frame 1.

[0123] It is understandable that the larger the V-shaped opening of the V-shaped support leg, the larger its lateral dimension, and the greater its rigidity or mechanical strength. Therefore, when the bracket is extended, the V-shaped support leg 11 can further increase the rigidity of the pocket-shaped support rod 3, preventing inward bending. In some embodiments, the V-shaped opening of the V-shaped support leg is greater than a set threshold. For example, the aforementioned set threshold can be between 30° and 60°, specifically 35°, 40°, 45°, 50°, 55°, etc.

[0124] Figure 4 is a second side view of the stent according to some embodiments of this specification. Figure 6 is a structural schematic diagram of the V-shaped support leg and the pocket-shaped support rod according to some embodiments of this specification. Referring to Figures 4 and 6, when the stent is opened, the V-shaped support leg 11 and the pocket-shaped support rod 3 protrude away from the central axis of the stent, making the side profile of the support appear as a drum-shaped structure. The V-shaped support leg 11 can provide good drum-shaped support force, preventing the pocket-shaped support rod 3 from bending inward after being compressed by the blood vessel. It can be understood that the height of the connection point between the V-shaped support leg 11 and the pocket-shaped support rod 3 in the axial direction of the stent is related to the V-shaped opening of the V-shaped support leg 11. The larger the V-shaped opening, the lower the height of the connection point in the axial direction, thereby shortening the length of the pocket-shaped support rod 3 and increasing the support stiffness. Therefore, by adjusting the height position of the aforementioned connection point in the axial direction of the stent, the support stiffness of the pocket-shaped space can be changed, allowing the stent to more effectively open the blood vessel while reducing the support force, thereby reducing damage to the blood vessel. As mentioned earlier, the S-shaped structural design can also increase support stiffness and prevent inward bending. In some embodiments, the distance between the upper endpoints of the two sides of the V-shaped support leg and the connection point of the two sides can be used as the length of the V-shaped support leg, as shown in Figure 6 as length h1. When the support is extended, the length of the V-shaped support leg 11 is less than the total length h2 of the one or more S-shaped portions 31 connected in sequence in the pocket-shaped support rod 3. Referring to Figures 2, 3, and 6, in some embodiments, the one or more S-shaped portions 31 connected in sequence in the pocket-shaped support rod 3 are connected to the distal segment support frame 4 by a straight rod 32, that is, the S-shaped portion of the pocket-shaped support rod 3 and the second end of the pocket-shaped support rod 3 are connected by a straight rod 32. The S-shaped portion can be structurally better transitioned by the straight rod to connect with the distal segment support frame. In some embodiments, the total length h2 of the one or more S-shaped portions 31 connected in sequence is greater than the length h3 of the straight rod 32. Experiments have shown that setting the length relationship of the V-shaped support leg, the S-shaped portion, and the straight rod in this way can make the pocket-shaped support rod easy to extend, and at the same time have good support rigidity after extension.

[0125] Figure 7 is a side view of Figure 6. When the bracket is extended, the pocket-shaped support rod resembles an arch, with the point furthest from the central axis of the bracket (as shown by the dotted line in Figure 7). Let's call this point the furthest point 33 in Figure 7, and the distance from the furthest point 33 to the central axis of the bracket is r1. As mentioned earlier, the height of the connection point between the V-shaped support leg 11 and the pocket-shaped support rod 3 in the axial direction of the bracket is related to the V-shaped opening of the V-shaped support leg 11. The larger the V-shaped opening, the lower the height of the connection point in the axial direction. Therefore, it can be understood that the V-shaped opening of the V-shaped support leg 11 is related to the height of the furthest point 33 in the axial direction of the bracket. At the same time, the V-shaped opening of the V-shaped support leg 11 also affects the length of the V-shaped support leg 11. Therefore, in some embodiments, the height of the furthest point 33 in the axial direction of the bracket is also related to the length of the V-shaped support leg 11. Thus, when designing the cut mesh surface of the support, by adjusting the length of the two sides of the V-shaped support leg 11, the V-shaped opening and / or length of the V-shaped support leg 11 when the support is opened can be adjusted, thereby adjusting the height of the farthest point 33 in the axial direction of the support.

[0126] In some embodiments, when the stent is deployed, the height of the farthest point 33 along the stent axial direction is equal to the height of the connection point between the leaflet fixation assembly 2 and the proximal support frame 1 along the stent axial direction. In other embodiments, when the stent is deployed, the farthest point 33 is closer to the distal support frame 4 along the stent axial direction relative to the connection point between the leaflet fixation assembly 2 and the proximal support frame 1. The offset of the point on the pocket-shaped support rod farthest from the central axis of the stent along the stent axial direction relative to the distal support frame further ensures the formation of a larger pocket-shaped space in the region near the proximal side of the leaflet 5, allowing blood to turbulently flow.

[0127] Figure 8 is a schematic diagram of the leaflet fixation assembly according to some embodiments of this specification. Referring to Figures 1, 3, and 8, in some embodiments, the leaflet fixation assembly 2 may include two curved rods 21 and 22 connected in a V-shape. The connection point 25 of the two curved rods is connected to the distal segment support frame 4. The outer end point 23 of the curved rod 21, away from the aforementioned connection point, is connected to the proximal segment support frame 1. The outer end point 24 of the curved rod 22, away from the aforementioned connection point, is also connected to the proximal segment support frame 1. The curved rod in the leaflet fixation assembly 2 is the junction of the leaflet and the support frame; for example, the leaflet can be sutured to the curved rod using sutures. The two curved rods are symmetrically designed, presenting a V-shaped structure in space. When the artificial valve expands in the vein, the curved rod in the leaflet fixation assembly can conform to the blood vessel, and combined with the leaflet, it can provide an axial seal, preventing blood leakage at the fixed edge of the leaflet.

[0128] In some embodiments, the curved rod may have two or more arcuate portions, specifically, two, three, or more arcuate portions. In some embodiments, a reference plane may be defined, in which the connection point 25, the external endpoint 23, and the external endpoint 24 of the leaflet fixing assembly are located; that is, the reference plane can be determined by these three points. Different arcuate portions in the curved rod may be distributed on different sides of the reference plane. Figure 9 is a schematic diagram of the structure of the curved rod in the leaflet fixing assembly according to some embodiments of this specification. Referring to Figures 1, 4, and 9, the curved rod 21 is exemplified. The curved rod 21 has an arcuate portion 211 and an arcuate portion 212. The dashed lines in Figure 9 represent the projection lines of the reference plane. The arcuate portion 211 is located on the lower side of the reference plane, and the arcuate portion 212 is located on the upper side of the reference plane.

[0129] Referring to Figures 1 and 4, it is easy to see that the upper side of the reference plane is also the proximal side, and the lower side is also the distal side. In some embodiments, among the two or more arcuate portions of the curved rod, the arcuate portion closer to the distal segment support frame (such as arcuate portion 242) is located on the upper side of the reference plane, i.e., the proximal side. This design allows for a certain creep margin for the leaflets in the stent structure, extending the service life of the artificial valve. For more information on the effects of creep, please refer to the subsequent description of the leaflets. As an example, the arcuate portion 212 shown in Figure 9 is closer to the distal segment support frame and is located on the proximal side of the reference plane, while the arcuate portion 211 farther from the distal segment support frame is located on the distal side of the reference plane.

[0130] As shown in Figures 1 and 4, in some embodiments, the number of leaflet fixation components 2 is two, and they are arranged opposite each other in the circumferential direction of the stent. The leaflets on the two leaflet fixation components can form a one-way valve structure in the axial direction of the blood vessel. In some embodiments, the pocket-shaped support rods can correspond one-to-one with the leaflet fixation components. Referring to Figure 3, the orthographic projection of the pocket-shaped support rod on the stent axial section is located between the orthographic projections of the two curved rods in the corresponding leaflet fixation component on the stent axial section. Thus, when the stent is deployed, a pocket-shaped space can be formed above the proximal side of each leaflet fixation component. In other embodiments, the number of pocket-shaped support rods can be greater, such as one leaflet fixation component corresponding to more than two pocket-shaped support rods. More pocket-shaped support rods can better support the pocket-shaped space of the leaflet fixation component to a certain extent. Continuing to refer to Figures 1 and 4, for any of the two sets of pocket-shaped support rods and leaflet fixation components, the orthographic projection of the pocket-shaped support rod on the stent axial section is located between the orthographic projections of the two curved rods in the leaflet fixation component on the stent axial section. The pocket-shaped space supported by the pocket-shaped support rods for the leaflet fixation component is more symmetrical and uniform.

[0131] In addition to the V-shaped support legs for connecting the pocket-shaped support rods, the proximal support frame also includes a proximal support grid for connecting the leaflet fixation assembly. Figure 11 is a second side view of the proximal support frame according to some embodiments of this specification. The proximal support grid 12 may have a V-shaped frame 121, in which a plurality of support rods 122 are fixedly connected to form one or more quadrilateral subgrids within the V-shaped frame 121. In other embodiments, a greater number of support rods 122 may be arranged in the V-shaped frame 121 to form a plurality of triangular subgrids. It is easy to understand that in yet another embodiment, the arrangement of the support rods 122 can be flexibly set to form at least one quadrilateral subgrid and at least one triangular subgrid within the V-shaped frame 121. The presence of the subgrids can increase the support stiffness of the V-shaped frame 121, allowing the proximal support grid 12 to support the blood vessel on the one hand, and to withstand the pressure of blood flow on the leaflets when the leaflets are closed on the other hand. In some embodiments, the density of the subgrid is positively correlated with the support stiffness, and the number of subgrids in the V-frame 121 can be adjusted according to factors such as the weight of the valve fixation assembly.

[0132] In some embodiments, the V-shaped opening of the V-frame 121 can be less than or equal to a set threshold, which can be between 30° and 60°, specifically 35°, 40°, 45°, 50°, 55°, etc. In some embodiments, the V-shaped frame 121 and the V-shaped support leg 11 can have the same set threshold, that is, in some embodiments, the V-shaped opening of the V-frame 121 can be no greater than the V-shaped opening of the V-shaped support leg 11. As mentioned above, the support stiffness of the V-shaped structure can be positively correlated with the V-shaped opening. In order to cooperate with the pocket-shaped support rod to form a larger pocket space, the V-shaped support leg 11 needs to have a larger support stiffness and deformation space. Therefore, its V-shaped opening can be appropriately increased to improve the support stiffness. At the same time, the simple frame structure of the V-shaped support leg 11 allows it to have a larger deformation space. Due to the limitations of the overall structure or size of the bracket, the V-shaped frame 121 can have a smaller V-shaped opening, while its support stiffness can be improved by several sub-grids in the V-shaped frame 121. Of course, in the actual implementation process, sub-grids can also be set in the V-shaped support feet according to the actual situation, and the size, shape and density of the sub-grids can also be changed.

[0133] The proximal support grid can be connected to the outer end of the curved rod. Specifically, the same proximal support grid can be connected to the outer end of the curved rod in different leaflet fixing assemblies. In other words, the outer end of two curved rods in the same leaflet fixing assembly are connected to different proximal support grids respectively. In this way, the V-shaped support feet and the proximal support grid can be alternately distributed along the axial direction of the support in the proximal support frame, providing support to the leaflet fixing assembly and the pocket-shaped support rod respectively.

[0134] Continuing with the example of a double-leaflet artificial valve, there are two leaflet fixation components, positioned opposite each other in the circumferential direction of the stent. Correspondingly, there are also two proximal support grids. The outer endpoints of one curved rod in the first leaflet fixation component and one curved rod in the second leaflet fixation component are both connected to the first proximal support grid. The outer endpoints of the other curved rod in the first leaflet fixation component and the other curved rod in the second leaflet fixation component are both connected to the second proximal support grid.

[0135] Referring to Figure 4, in some embodiments, a positioning ear 6 is also connected between the outer end of the curved rod of the leaflet fixation assembly and the proximal support grid 12. As shown in Figure 9, in some embodiments, the positioning ear 6 may be provided with one or more positioning holes 61. The positioning holes 61 are used to fix the leaflets, such as the corresponding parts of the leaflets (e.g., the leaflet auricles) can be fixed in the positioning holes with sutures. In some embodiments, the positioning ear can also be regarded as part of the leaflet fixation assembly. Taking a double-leaflet artificial valve as an example, the outer end of one curved rod in the first leaflet fixation assembly and the outer end of one curved rod in the second leaflet fixation assembly are both connected to the first positioning ear, and the first positioning ear is connected to the first proximal support grid; the outer end of the other curved rod in the first leaflet fixation assembly and the outer end of the other curved rod in the second leaflet fixation assembly are both connected to the second positioning ear, and the second positioning ear is connected to the second proximal support grid. As shown in Figure 4, two positioning holes can be provided on the positioning ear 6 along the axial direction of the stent, thus achieving double fixation of the corresponding parts of the leaflets and preventing the leaflets from shifting to the distal segment due to blood flow pressure.

[0136] The distal support grid is used to support the distal blood vessel. In some embodiments, the distal segment support frame may have a grid structure. Figures 12 and 13 illustrate the structure of the distal segment support frame from a first lateral view and a second lateral view, respectively. The distal segment support frame may include a distal segment support grid, which may be arranged below the curved rod of the leaflet fixation assembly to support the leaflet fixation assembly.

[0137] Referring to Figures 1, 4, and 13, taking a double-leaf artificial valve as an example, in some embodiments, a first distal segment support grid is provided below one of the curved rods in the first leaflet fixing assembly and one of the curved rods in the second leaflet fixing assembly, which are connected together by external endpoints; a second distal segment support grid is provided below the other curved rod in the first leaflet fixing assembly and the other curved rod in the second leaflet fixing assembly.

[0138] Figure 12 shows a side view of the first and second distal segment support grids from a first lateral perspective. The two distal segment support grids are distinguished by a dashed line; that is, the sides of the dashed line represent the side views of different distal segment support grids 41. Referring to Figure 13, in some embodiments, the distal segment support grid 41 has a W-shaped frame 411 containing several supports 412 to form one or more triangular sub-grids and / or one or more quadrilateral sub-grids. Further description of the supports forming sub-grids can be found in the foregoing description of the proximal segment support grid, and will not be repeated here.

[0139] Figure 14 is a second side view of the stent according to some other embodiments of this specification. As shown in Figures 13 and 14, in some embodiments, a barrier membrane 8 may be fixed on the distal support mesh 41. In some embodiments, the material of the barrier membrane may include a polymeric material or a bio-derived material, wherein the polymeric material may further be polysiloxane, polytetrafluoroethylene, polyurethane, or styrene polymer, etc., and the bio-derived material may further be porcine pericardium, porcine heart valve, bovine pericardium, or bovine heart valve, etc. After the artificial valve has been in the blood vessel for a period of time, biological tissues from an organism (such as the human body) may proliferate and gradually cover the artificial valve. Compared to a metal stent, biological tissues are more likely to adhere to the leaflets, which have similar material properties. When biological tissues proliferate and cover the leaflets, the thickness of the leaflets increases, thereby affecting the opening and closing sensitivity. The barrier membrane has a material similar to or the same as the leaflets and can "drain" at least part of the proliferating biological tissues, thereby hindering or reducing the proliferation of biological tissues on the leaflets and extending the service life of the artificial valve. Simultaneously, when biological tissues proliferate and coat the barrier membrane, they can increase the adhesion between the stent and the blood vessel, thereby preventing stent displacement within the vessel and increasing the circumferential seal of the artificial valve. The mesh structure of the distal segment support grid is even more conducive to fixing the barrier membrane.

[0140] Referring to Figure 3, in some embodiments, the connection point of the two curved rods in the leaflet fixing assembly can be connected to one end of the W-shaped frame via a positioning rod 7. The positioning rod can be used to fix the corresponding part of the leaflet (such as the positioning part of the leaflet), and in some embodiments, the positioning rod can be regarded as part of the leaflet fixing assembly. Referring to Figures 1, 4, and 13, taking a double-leaflet artificial valve as an example, in some embodiments, the connection point of the two curved rods in the first leaflet fixing assembly can be connected to one end of the first W-shaped frame and one end of the second W-shaped frame via a first positioning rod; the connection point of the two curved rods in the second leaflet fixing assembly can be connected to the other end of the first W-shaped frame and the other end of the second W-shaped frame via a second positioning rod. One end of some of the support rods 412 in the W-shaped frame 411 can be connected to the curved rod of the corresponding leaflet fixing assembly to increase stability.

[0141] Figure 15 is a side view of the stent according to some embodiments of this specification. As shown in Figure 15, in some embodiments, when the stent is deployed, its proximal support frame has an inverted truncated pyramidal structure, with the cubital support rod and leaflet fixing assembly bulging radially away from the central axis to form a cubital or drum-shaped structure, while the distal support frame has a regular truncated pyramidal structure. As shown in Figure 15, when the artificial valve leaflets are closed (or simply referred to as artificial valve closure), blood can flow around the drum-shaped area, preventing blood stasis and thrombus formation.

[0142] Generally, a frustum can be defined as the portion between the base and the cross-section obtained by cutting the cone with a plane parallel to its base. The frustum can be considered to have two bases, an upper and a lower one. The cross-section of the frustum or cone can be of any shape, such as a triangle, polygon, circle, ellipse, etc. The maximum radial dimension of the upper base of an inverted frustum is greater than that of the lower base, while the maximum radial dimension of the upper base of a normal frustum is smaller than that of the lower base. Taking a frustum with a circular cross-section as an example, the diameter of the upper base of an inverted frustum is greater than that of the lower base, while the diameter of the upper base of a normal frustum is smaller than that of the lower base. Taking a frustum with an elliptical cross-section as another example, the major axis of the upper base of an inverted frustum is greater than that of the lower base, while the major axis of the upper base of a normal frustum is smaller than that of the lower base. It should be noted that in some embodiments of this specification, unless otherwise specified, "upper" corresponds to the proximal end or proximal side, and "lower" corresponds to the distal end or distal side.

[0143] In some embodiments, when the stent expands, the pocket-shaped support rod bulges further away from the stent's central axis relative to the leaflet fixation assembly. Correspondingly, the proximal support frame supporting both can be an inverted truncated pyramid with an elliptical or nearly elliptical cross-section, while the distal support frame can be a regular truncated pyramid with an elliptical or nearly elliptical cross-section. When the stent expands, its proximal support frame has an inverted truncated pyramid structure, meaning the upper end of the proximal support frame is radially or open, allowing it to expand the blood vessel radially to a certain extent while remaining more closely attached to the vessel wall. This design effectively prevents blood pressure from causing the stent to shift axially towards the distal side when the artificial valve closes, thus reliably fixing the stent in the implantation position. Conversely, the distal support frame has a regular truncated pyramid structure, meaning the lower end of the distal support frame is radially or open, allowing it to expand the blood vessel radially to a certain extent while remaining more closely attached to the vessel wall. This design effectively prevents blood impact from causing the stent to shift axially towards the proximal side when the artificial valve opens. Of course, overall, the larger radial dimensions of the openings at both ends of the stent can better fix the stent in the blood vessel and prevent the stent from shifting along the axial direction of the blood vessel.

[0144] The base angle can be understood as the angle between a straight line passing through the center of the base surface and the corresponding generatrix on the base surface of the platform. The upper base angle is the angle between a straight line passing through the center of the base surface and the corresponding generatrix on the upper base surface of the platform, and the lower base angle is the angle between a straight line passing through the center of the base surface and the corresponding generatrix on the lower base surface of the platform. In some embodiments, the minimum upper base angle of the inverted truncated pyramid formed by the proximal support frame is smaller than the minimum lower base angle of the upright truncated pyramid formed by the distal support frame. This means that the upper opening size of the proximal support frame can be larger than the lower opening size of the distal support frame in a certain radial direction. When the artificial valve is closed, the pressure exerted by the blood on the artificial valve towards the distal end is greater than the pressure exerted by the blood impact on the artificial valve towards the proximal end when the artificial valve is open. Therefore, a larger upper opening of the stent can better counteract the greater pressure exerted by the blood on the artificial valve towards the distal end. In some embodiments, the angle of the minimum upper base angle of the inverted truncated pyramid corresponding to the proximal support frame is taken from the numerical range of 75° to 85°, and the angle of the minimum lower base angle of the truncated pyramid is taken from the numerical range of 80° to 87°. Taking an elliptical cross-section of the outer contour of the support frame as an example, the angle formed by the major axis of the upper base of the inverted truncated pyramid of the proximal support frame and the generatrix is ​​the minimum upper base angle, as shown by α1 in Figure 15; the angle formed by the major axis of the lower base of the upright truncated pyramid of the distal support frame and the generatrix is ​​the minimum lower base angle, as shown by α2 in Figure 15, where α1 < α2. As an example, α1 can be 82° and α2 can be 85°.

[0145] As mentioned earlier, when the artificial valve expands in the blood vessel, the leaflet fixation assembly can conform to the blood vessel, and the leaflets together can provide an axial seal for the blood vessel, preventing blood leakage around the stent. In some embodiments, to further improve the sealing performance of the leaflet fixation assembly, the rods constituting the leaflet fixation assembly can have a larger radial dimension, thereby increasing the contact area between the leaflet fixation assembly and the blood vessel wall, resulting in a better sealing effect. In some embodiments, the rod can be a basic structural unit constituting the stent, and the radial dimension of the rod can specifically be the radial dimension in one or more directions on the cross-section of the rod, such as the width, thickness, diameter, major axis, minor axis, etc. For the leaflet fixation assembly 2, the rod can include curved rods 21 and 22. In some embodiments, the rods in the leaflet fixation assembly have a larger dimension on their cross-section in the direction parallel to the contact surface between the rod and the blood vessel wall, in order to increase the contact area between the rods in the leaflet fixation assembly and the blood vessel wall.

[0146] Figure 16 shows a cut surface of the support according to some other embodiments of this specification. Similar to Figure 2, Figure 16 uses dashed lines to illustrate the connection between the proximal support frame 1 and the leaflet fixation assembly 2 and the pocket-shaped support rod 3, and uses double-dotted lines to illustrate the connection between the distal support frame 1 and the leaflet fixation assembly 2 and the pocket-shaped support rod 3. In some embodiments, the radial dimension of the rod constituting the leaflet fixation assembly can be 0.1 mm to 0.5 mm. Taking Figure 16 as an example, the width d1 of the rod constituting the leaflet fixation assembly 1 can be 0.2 mm, 0.3 mm, 0.4 mm, etc.

[0147] In some embodiments, the radial dimension of the rods constituting the leaflet fixing assembly is larger than the radial dimension of the rods constituting the rest of the support. The rest of the support may include one or more of the following: a proximal support frame, a pocket-shaped support rod, and a distal support frame. In some embodiments, for the proximal support frame 1, the rods may include rods constituting the V-shaped support foot 11, rods constituting the V-shaped frame 121, and a plurality of support rods 122. For the pocket-shaped support rod 3, the rods may include bent rods constituting the S-shaped portion 31 and straight rods 32. For the distal support frame 4, the rods may include rods constituting the W-shaped frame 411 and support rods 412.

[0148] Referring again to Figure 16, in some embodiments, the width d1 of the rods constituting the leaflet fixation assembly is greater than the width of the rods constituting the rest of the stent, and greater than the width d2 of the rods in the proximal support frame 1. This design ensures that when the stent expands in the blood vessel, the contact area per unit length between the rods constituting the leaflet fixation assembly 1 and the blood vessel is greater than the contact area per unit length between the rods constituting the rest of the stent and the blood vessel. The unit length is introduced for ease of comparison; it can be flexibly set according to the specific length of the stent or stent portion. For example, the unit length can be 1 mm, 2 mm, 1 cm, etc. In some embodiments, the radial dimension of the rods constituting the leaflet fixation assembly can be n times the radial dimension of the rods constituting the rest of the stent, where 1 < n ≤ 2. For example, n can be 1.2, 1.5, 1.8, etc.

[0149] In some other embodiments, a sealing membrane is provided around the stent to increase sealing performance, for example, a sealing membrane is wrapped around the distal segment support of the stent. In contrast, some embodiments of this specification achieve improved sealing performance by increasing the radial dimension of the rods that make up the leaflet fixation assembly, which can eliminate the need for a sealing membrane and make the structure of the artificial valve more streamlined.

[0150] For artificial valves, leaflets are also fixed to the leaflet fixation assembly of the stent. The leaflets can be made of bio-derived materials such as porcine pericardium, porcine heart valves, bovine pericardium, and bovine heart valves, or various polymer materials. Figure 17 is a schematic diagram of the leaflets according to some embodiments of this specification. As shown in Figure 17, the leaflets are in a flat state, and leaflet 5 has a fixed edge 51. The fixed edge 51 can be used to fix it to the leaflet fixation assembly. Specifically, the fixed edge 51 of leaflet 5 is fixed to two curved rods connected in a V-shape in the leaflet fixation assembly, so the fixed edge 51 can have an arc-shaped edge adapted to the curved rods. Leaflet 5 also has a free edge 52, which is located between the two ends of the fixed edge 51 of leaflet. The free edge 52 is not fixed to the leaflet fixation assembly and is in an open, free state. In artificial valves, the free edge 52 of leaflet will form an opening for blood flow.

[0151] To further reinforce the leaflets, the leaflet 5 shown in Figure 17 may further include a first leaflet ear 53, a second leaflet ear 54, and a positioning part 55. The first leaflet ear 53 and the second leaflet ear 54 are respectively fixed to the first and second positioning ears of the corresponding leaflet fixing components in the bracket, and the positioning part 55 is fixed to the positioning rod connected to the connection point of the two curved rods in the corresponding leaflet fixing components. The leaflet ear and the positioning part also help to improve the suturing efficiency of the leaflets. Specifically, in the artificial valve manufacturing process, the leaflet ears on both sides of the leaflet can be fixed to the positioning ears of the leaflet fixing components using sutures, and the positioning part at the bottom of the leaflet can be fixed to the positioning rod using sutures. Then, the leaflet is sutured to the curved rod along the fixed edge.

[0152] In some embodiments, the corresponding portion of the leaflet can be fixed to the leaflet fixation component by suturing. There are various implementation methods for suturing the leaflets. For example, the leaflet suture can cover the corresponding portion of the leaflet fixation component (such as the crank, positioning lug, or positioning rod) (referred to as a full-coverage suture), or the leaflet suture can only adhere to the inner surface of the corresponding portion of the leaflet fixation component (referred to as a partial-coverage suture). The full-coverage suture allows the blood vessel to contact the flexible leaflet, which is more conducive to sealing. The partial-coverage suture keeps the leaflet away from the blood vessel, preventing the adhesion of biological tissue and avoiding leaflet thickening that could lead to leaflet dysfunction.

[0153] The stent and leaflets constitute a complete artificial valve. In some embodiments, depending on the number of leaflets in the artificial valve, it can be referred to as a single-leaflet valve, a bicuspid valve, or a tricuspid valve. The foregoing embodiments are mainly described using a bicuspid valve as an example. In a bicuspid valve, there are two leaflet fixing components, which are arranged opposite each other in the circumferential direction of the stent. After the leaflets are sutured to the leaflet fixing components, the free edges of the two leaflets cooperate to form a one-way valve in the artificial valve that allows blood flow. Figures 18 and 19 respectively show the first and second states of a bicuspid artificial venous valve in a vein according to some embodiments of this specification. In Figure 18, the pressure at the proximal end (upper end) is higher than that at the distal end (lower end), at which point the free edges of the two leaflets in the artificial valve are adhered together, and the artificial valve is closed. In Figure 19, the pressure at the distal end (lower end) is higher than that at the proximal end (upper end), at which point the free edges of the two leaflets in the artificial valve are separated by blood flow, and the artificial valve is open. In this way, artificial valves can replace the native valves in veins and prevent blood from flowing backward.

[0154] Referring again to Figure 17, in some embodiments, the free edge 52 of the leaflet 5 is an arcuate edge convex towards its fixed edge 51. This design effectively prevents the upper edges of the free edges 52 of the two leaflets from bending away and separating due to excessive contact area after they are joined together, thus preventing incomplete valve closure. This will be explained below with reference to Figures 20-22.

[0155] As shown on the left side of Figure 20, the pressure at the distal end of the valve is greater than the pressure at the proximal end, causing the valve leaflets to open due to blood flow, forming an interleaflet opening 56, allowing venous blood to flow back to the heart. As the pressure at the distal end of the valve increases further, the interleaflet opening will further enlarge, as shown on the right side of Figure 20. As shown in Figure 21, the pressure at the proximal end of the valve begins to increase and gradually exceeds the pressure at the distal end, at which point the valve leaflets begin to adhere. As shown in Figure 22, as the pressure at the proximal end of the valve increases further, the area of ​​adhesion between the two valve leaflets will shift towards the distal end under the blood pressure from the proximal end. If the free edge 52 of the leaflet is a straight edge, a contact area is easily formed when the two leaflets are attached. This contact area can be located in the leaflet contact area 57, which is above the free edge of the leaflet and enclosed by the dotted line, as shown in Figures 21 and 22. As the pressure near the heart of the valve increases further, the area of ​​the contact area will increase further, which may eventually cause the upper edge of the straight free edge of the two leaflets to bend backward and separate, resulting in incomplete valve closure, as shown on the right side of Figure 22 from the side of the two leaflets. The two arc-shaped dotted lines represent the lateral contours of the two leaflets, respectively. At this time, blood near the heart of the valve is prone to backflow, leading to valve failure. If the free edge 52 of the leaflet is designed as an arc-shaped edge convex to its fixed edge 52, the area of ​​the leaflet contact area can be effectively reduced, avoiding the backward bending of the free edge and improving the reliability of the artificial valve. Experimental data show that when the blood pressure in the vein is between 3 mmHg and 300 mmHg, the leaflets provided in some embodiments of this specification will not bend backwards in the artificial valve.

[0156] Some embodiments of this specification also provide a single-leaflet artificial valve. Referring to Figure 23, the stent of the single-leaflet artificial valve includes a proximal support frame, a leaflet fixation assembly, a fixation accessory, a pocket-shaped support rod, and a distal support frame. The leaflet fixation assembly is connected between the proximal and distal support frames and is used to fix the leaflet. The fixation accessory is connected between the proximal and distal support frames and is disposed opposite to the leaflet fixation assembly in the circumferential direction of the stent. The pocket-shaped support rod is arranged along the axial direction of the stent, with its first end connected to the proximal support frame and its second end connected to the distal support frame. When the stent is opened, the pocket-shaped support rod can protrude radially away from the central axis of the stent to form a pocket-shaped space on the proximal side of the leaflet fixation assembly.

[0157] Comparing Figures 1 and 4, it is easy to see that the single-leaflet artificial valve stents provided in some embodiments of this specification are simplified compared to the double-leaflet artificial valve stents. Specifically, the single-leaflet artificial valve stent contains only a single leaflet fixing component. To ensure the support effect of the stent, one of the leaflet fixing components in the double-leaflet artificial valve stent can be used as a fixing accessory, with the same structure as the leaflet fixing component, except that no leaflet is fixed thereon. Correspondingly, in the single-leaflet artificial valve stent, the pocket-shaped support rod is only arranged at the leaflet fixing component. Specifically, the position of the pocket-shaped support rod is such that its orthographic projection on the axial section of the stent lies between the orthographic projections of the two curved rods in the leaflet fixing component on the axial section of the stent. For the specific structure or construction of the proximal support frame, leaflet fixing component, fixing accessory, pocket-shaped support rod, and distal support frame in the single-leaflet artificial valve stent, please refer to the description of the foregoing embodiments, which will not be repeated here.

[0158] Figure 24 is a diagram showing the state of the artificial venous valve shown in Figure 23 within a vein. A single leaflet forms a one-way valve with the opposite vessel wall. When the pressure at the proximal end of the valve is less than the pressure at the distal end, leaflet 5 separates from the opposite vessel wall, and blood in the vein flows back to the heart. When the pressure at the proximal end of the valve is greater than the pressure at the distal end, the pocket-shaped space on the proximal side of leaflet 5 fills with blood. Under the pressure of the blood, leaflet 5 expands and fills towards the distal end. At this point, the free edge of leaflet 5 adheres to the vessel wall, and the artificial valve closes.

[0159] It should be understood that although the embodiments in this specification mainly describe two-leaflet and single-leaflet artificial valves, those skilled in the art can apply the relevant features to three-leaflet or other artificial valves based on the principles and structures described in the embodiments in this specification. Therefore, the modified embodiments obtained by applying the features of the embodiments in this specification are still within the scope of this specification.

[0160] This specification provides an artificial venous valve leaflet (or leaflet) in some embodiments, wherein the leaflet 5 includes: a free edge 52, a fixed edge 51 with both ends connected to the two ends of the free edge 52 to form a boundary, and a leaflet curved surface 9 defined within the boundary. The fixed edge 51 is configured to be directly or indirectly fixed to the inner wall of the vein, and the free edge 52 is configured to cooperate with a mating portion to achieve opening and closing, thereby realizing a one-way valve function. It should be noted that the artificial venous valve leaflet is installed at a first position in the vein, and the artificial venous valve leaflet, through the aforementioned opening and closing, allows blood to pass through the first position of the vein or prevents blood from passing through the first position of the vein.

[0161] Referring to Figures 25 to 27, Figure 25 shows the spline curve 91, Figure 26 shows the first surface A on which the leaflet surface 9 is located, and Figure 27 shows the leaflet surface 9 and the first surface A on which the leaflet surface 9 is located. In some embodiments, the leaflet surface 9 is configured such that its projection on at least one axial section of the vein is a spline curve 91 (or is considered to be on a certain spline curve).

[0162] Spline curve 91 is a smooth curve that is continuous and has a uniform curvature. For ease of explanation, spline curve 91 can be understood as a curve with one endpoint (i.e., endpoint o in Figure 25) that extends from that endpoint toward the distal end.

[0163] The leaflet surface 9 is a curved surface. Although the leaflet 5 actually has a certain thickness, for ease of understanding and calculation, in some embodiments, the center surface of the leaflet 5 in the projection direction can be approximated as the leaflet surface 9; in other embodiments, the surface of one side of the leaflet 5 can also be approximated as the leaflet surface 9.

[0164] In some embodiments, the spline curve 91 includes a main body portion. In other embodiments, the spline curve 91 includes a start portion, a main body portion, and an end portion connected sequentially from the proximal end to the distal end. Of course, in other embodiments, the spline curve 91 may also include a start portion and a main body portion, or a main body portion and an end portion.

[0165] A coordinate system is established with the center of the diametrical plane of the vein where leaflet 5 is located as the origin, the projection direction of the projection as the y-axis, the axial direction of the vein as the z-axis, and the direction orthogonal to the y-axis and z-axis as the x-axis. In this coordinate system, the slope of the tangent at any point on the main body of spline curve 91 is either non-positive or non-negative.

[0166] In other words, in some embodiments, the tangent at any point on the main body of the spline curve 91 is negative or zero in this coordinate system; in other embodiments, the tangent at any point on the main body of the spline curve 91 is positive or zero in this coordinate system.

[0167] In other words, in some embodiments, the main body of spline curve 91 monotonically increases or monotonically decreases within this coordinate system.

[0168] In some embodiments, the starting and ending portions of the spline curve 91 may not have a slope. In other words, the starting and ending portions of the spline curve 91 are parallel to the z-axis.

[0169] In some embodiments, the starting and ending portions of the spline curve 91 may be line segments. Furthermore, the starting portion of the spline curve 91 may also be an endpoint.

[0170] The design of the spline curve 91, which is monotonically increasing or decreasing, avoids the formation of multiple segmented regions. Referring to Figure 35, the non-monotonic decreasing spline curve produces relatively closed U-shaped regions e and f. Simultaneously, it forms two regions on the proximal side: the U-shaped region e and the near-triangular region g. It also forms two regions on the distal side: the U-shaped region f and the near-triangular region h. Because each side's region is divided into two parts, blood flow is impaired, easily leading to blood stasis and thrombosis.

[0171] The monotonic spline curve 91 in some embodiments described herein avoids the formation of multiple segmented regions on the proximal and distal sides, and its region on the proximal side is arranged in a single pocket shape, which helps to guide blood flow around the periphery.

[0172] Referring again to Figure 25, the main body of spline curve 91 includes, in sequence: a first segment 911 extending along the axial direction of the vein, a second segment 912 extending outward toward the radial direction of the vein, and a third segment 913 extending toward the axial direction of the vein.

[0173] In some embodiments, the absolute value of the slope of the second segment 912 of the spline curve 91 can be less than the absolute value of the slopes of the first segment 911 and the third segment 913, so as to form a relatively gentle plateau between the first segment 911 and the third segment 913. The plateau formed by the second segment 912 makes the leaflet surface 9 have a contact surface with blood. Compared with other parts of the leaflet surface 9, the angle between this contact surface and the blood flow direction is larger. In some embodiments, this angle is orthogonal or nearly orthogonal, so that there is a large force-bearing surface between the leaflet 5 and the blood in the venous vessel. The component force of blood distribution / acting on this force-bearing surface is larger. When blood acts on the plateau, it can respond quickly and stably according to the blood flow, and further drive the first segment 911 and the third segment 913 to deform until the leaflet 5 is fully opened or closed. The design of the spline curve 91 as monotonically increasing or decreasing further improves the response speed of the plateau. Referring to Figure 35, the deformation of a non-monotonic spline curve is significantly more difficult than that of a monotonically decreasing spline curve 91 shown in Figure 25. Specifically, to close or open blood vessels, the deformation of the first and third segments of a non-monotonic spline curve is greater than that of the first and third segments of a monotonic spline curve. Furthermore, it requires a greater pressure component from the blood flow at the plateau. Therefore, valve leaflets designed based on non-monotonic splines exhibit a slower and more unstable response to blood flow.

[0174] The first segment 911, and in some embodiments the starting portion connected to the first segment 911, provides the leaflet 5 with a portion that cooperates with the mating portion to form a seal.

[0175] The third segment 913 and, in some embodiments, the ending portion connected to the third segment 913, provide a portion for fixing the leaflet 5 to the leaflet fixing assembly, for example, providing a portion for stitching the leaflet 5 to two curved rods connected in a V-shape in the leaflet fixing assembly.

[0176] In addition, the third segment provides a portion for the leaflet 5 to cooperate with the pocket-shaped support rod 3 and the blood vessel wall supported by the pocket-shaped support rod 3 to form a pocket-shaped space.

[0177] Generally speaking, in one or more embodiments of this specification, the spline curve 91 specifically includes, from the proximal end to the distal end, the following in sequence: a starting portion parallel to the z-axis or with a tangent parallel to the z-axis; a first segment 911 extending from the starting portion along the axis of the vein toward the distal direction and slightly offset outward in the radial direction of the vein; a second segment 912 mainly curving and extending outward in the radial direction of the vein; a third segment 913 extending from the second segment 912 along the axis of the vein toward the distal direction and further slightly offset outward in the radial direction of the vein; and an ending portion parallel to the z-axis or with a tangent parallel to the z-axis.

[0178] During muscle contraction / relaxation and respiration, blood mainly acts on the distal side of the surface where the second segment 912 is located, causing deformation of the surface at the second segment 912 and the surface at the first segment 911. This changes the absolute value of the slope of the surface at the second segment 912, increasing the absolute value of the slope and causing it to extend from approximately along the radial direction of the vein to approximately along the axial direction of the vein. This, in turn, drives the surface at the first segment 911 and further opens the free edge 52.

[0179] During muscle contraction / relaxation and respiration, the proximal side of the curved surface where the second segment 912 is located is subjected to blood pressure, which causes deformation of the curved surface at the second segment 912 and the curved surface at the first segment 911. This causes the curved surface at the second segment 912 to return to a state that extends roughly in the radial direction of the vein, thereby driving the curved surface at the first segment 911 to further close the free edge 52.

[0180] For example, in a resting state, venous blood flows back to the heart with respiration; when a muscle contracts, the valves on the proximal end of the muscle open, allowing venous blood to flow back to the heart; when a muscle relaxes, the valves on the proximal end of the muscle close to prevent backflow of blood, while the valves on the distal end of the muscle or the valves on the communicating veins open to allow blood to flow back.

[0181] In one or more embodiments of this specification, the fixed edge 51 is a spatial curve, and the fixed edge 51 is located on the side surface of a cylinder 92. It should be noted that the side surface of the cylinder 92 refers to the cylindrical surface of the cylinder, that is, an annular arc surface with a uniform diameter. Referring to Figure 29, in some embodiments, the diameter d3 of the cylinder 92 ranges from 2 to 15 mm, and the height h1 of the cylinder 92 ranges from 2 to 20 mm. For example, the diameter d3 of the cylinder 92 can range from 2 mm, 2.5 mm, 3 mm, 5 mm, 6.8 mm, 7.5 mm, 8 mm, 9 mm, 11 mm, 11.2 mm, 11.5 mm, 13 mm, 14 mm, to 15 mm. For example, the height h1 of cylinder 92 ranges from 5 to 15 mm. Exemplarily, the height h1 of cylinder 92 can be 2 mm, 2.1 mm, 3 mm, 4 mm, 5 mm, 8 mm, 12 mm, 13.5 mm, 14 mm, 15 mm, 15.5 mm, 15.8 mm, 17 mm, 18 mm, 18.8 mm, or 20 mm. Given that the fixed edge 51 is located on the side of cylinder 92, it has good adaptability to the shape of the inner wall of the vein.

[0182] Referring to Figure 28, the first straight line l1 formed by the proximal endpoint o of the spline curve 91 moving along the projection direction has a distance D1 between it and the axis of the cylinder 92. In some embodiments, the distance D1 ranges from 0 to 1 mm. For example, the distance D1 can be 0.05 mm, 0.1 mm, 0.2 mm, 0.35 mm, 0.5 mm, 0.68 mm, 0.8 mm, or 1 mm. The distance D1 provides a reserved space for the thickness of the leaflet 5. After the leaflet 5 is cut, this reserved space allows the leaflet 5 and the mating part to have suitable mechanical properties, that is, the side of the leaflet 5 just fits against the mating part and retains a certain fitting force, without making the force exerted by the leaflet 5 on the mating part too large or too small, thereby avoiding stress deformation, fatigue, and damage to the leaflet 5 and the mating part.

[0183] Referring to Figure 33, in some embodiments, the free edge 52 is an arc-shaped edge convex to its fixed edge, and the value of the projected height h2 of the arc-shaped edge on the axial section of the vein ranges from 0 to 10 mm. For example, the value of the projected height h2 of the arc-shaped edge on the axial section of the vein ranges from 2 to 8 mm. Exemplarily, the value of the projected height h2 of the arc-shaped edge on the axial section of the vein is 0.1 mm, 1 mm, 2 mm, 5 mm, 7.5 mm, 9 mm, or 10 mm. In some embodiments, the value of the projected height h2 of the arc-shaped edge on the axial section of the vein is 0 to 2 / 3 times the value of the projected height h3 of the leaflet 5 on the axial section of the vein. Exemplarily, the value of the projected height h3 of the arc-shaped edge on the axial section of the vein is 1 / 5, 1 / 4, 1 / 3, or 1 / 2 times the value of the projected height h3 of the leaflet 5 on the axial section of the vein.

[0184] In some embodiments, the mating portion is: the free edge of another artificial venous valve leaflet, or a second stent, or the inner wall of the vein. Specifically, in a bicuspid valve embodiment, the mating portion is the free edge of another artificial venous valve leaflet. In a tricuspid valve embodiment, the mating portion is the free edge of two other artificial venous valve leaflets. In a unicuspid valve, the mating portion can be part of a second stent disposed on the inner wall of the vein, or it can be the inner wall of the vein itself. For example, specifically referring to Figure 24, the leaflet 5 is disposed on the second stent. In Figure 24, the mating portion is the inner wall of the vein, and the free edge 52 of the leaflet 5 is attached to the inner wall of the vein. In some further embodiments, the second stent may have a second support rod (not shown in the figure) attached to the inner wall of the vein, and the free edge 52 of the leaflet 5 is attached to the second support rod. Of course, in other possible applications, this type of artificial venous valve leaflet can also be applied to other possible forms of valves besides unicuspid, bicuspid, and tricuspid valves, and the mating portion is selected according to the corresponding structure and actual needs.

[0185] The leaflet surface 9 includes a first arcuate surface and a second arcuate surface with opposite convex directions. The first arcuate surface is closer to the proximal end than the second arcuate surface, and the first arcuate surface convexes towards the distal end, while the second arcuate surface convexes towards the proximal end. The projection of the first arcuate surface forms the first segment 911 of the spline curve, and the projection of the second arcuate surface forms the third segment 913 of the spline curve.

[0186] The leaflet surface 9 is configured to form a pocket-shaped space between it and the vein wall on the proximal side.

[0187] Some embodiments of this specification also provide a method for designing an artificial venous valve leaflet for forming an artificial venous valve leaflet, the artificial venous valve leaflet comprising: a free edge 52, a fixed edge 51 with both ends connected to the two ends of the free edge 52 to form a boundary, and a leaflet surface 9 confined within the boundary; the fixed edge 51 is configured to be directly or indirectly fixed to the inner wall of the vein; the free edge 52 is configured to cooperate with a mating portion to close or open the vein to achieve a one-way valve function.

[0188] The design method for artificial venous valve leaflets includes: providing a single curve 91; making a scan line l s (For example, sweeping a straight line or sweeping curve) sweep along spline curve 91 starting from its proximal endpoint to obtain the first surface A; provide a trimmed cylinder (i.e., cylinder 92) such that the sweep line l passing through the proximal endpoint of spline curve 91 s The first curved surface A is coplanar with the plane of the cut cylinder, so that the first curved surface A intersects with the side surface of the cut cylinder; the part of the first curved surface A located outside the cut cylinder is removed to obtain the second curved surface B, and the cut part of the second curved surface B by the cut cylinder forms a fixed edge 51; wherein, the leaf curved surface 9 is located inside the second curved surface B.

[0189] See Figure 26 for details. The dashed line in Figure 26 shows the spline curve 91. The sweep line l is also defined in Figure 26. s In some embodiments, the sweep line l s The line is a straight line. In other embodiments, the sweep line l is... s For curves. Sweep line l s Translation along the direction of spline curve 91 yields a surface with the bending characteristics of spline curve 91, which is the first surface A. Referring to Figure 27, which shows a trimmed cylinder (i.e., cylinder 92), cylinder 92 has an upper end face and a lower end face, and the sweep line l passing through the proximal endpoint of spline curve 91... s Arranged within the upper surface of cylinder 92, the first curved surface intersects with the side surface of cylinder 92. The side surface of cylinder 92 divides the first curved surface A into a dark area and a white area, where the dark area is the second curved surface B. The dividing line of cylinder 92 that divides the first curved surface A, i.e., the position where the second curved surface is cut by cylinder 92, forms a fixed edge 51.

[0190] In some embodiments, the second surface B can be directly used as the leaf surface 9. Referring to Figure 33, in other embodiments, a trimming curve 1 can be further provided. c According to the cutting curve l c The edges on the second surface B, excluding the fixed edge 51, are trimmed to form a free edge 52. The shaded area on the left side of Figure 33 shows the trimmed area.

[0191] Referring to Figures 31 to 33, in some embodiments, when the fixing edge 51 is configured to be directly or indirectly fixed to the inner wall of the vein and the second curved surface B bulges towards the distal end, the second curved surface B and the mating portion have an overlapping area C, and the trimming curve l c The edge of the overlapping region is used to determine whether the curve is located within the overlapping region C. Specifically, the trimming curve l c It is the edge of the overlapping region C, or part of the edge of the overlapping region C, or falls within the plane containing the overlapping region C. Select the clipping curve l from within the overlapping region C. c This helps ensure the sealing of leaflet 5 during operation.

[0192] Furthermore, in some embodiments, the trimming curve l c It is configured such that when the fixed edge 51 is configured to be directly or indirectly fixed to the inner wall of the vein and the second curved surface bulges toward the distal end, the free edge 52 formed by the cut curve 51 remains in contact with the mating part.

[0193] In one or more embodiments of this specification, the design of the trimming curve l is also provided. c The method includes: determining the mating part; establishing a model such that the fixed edge 51 of the second curved surface B fits against the vein, and the edges of the second curved surface B other than the fixed edge 51 fit against the mating part; forming a sealing line or sealing surface between the second curved surface B and the mating part (for example, forming a sealing line or sealing surface between the second curved surface B and the mating part under normal conditions, or forming a sealing line or sealing surface when the second curved surface B bulges towards the distal end); and trimming curve l. c For sealing lines, or for cutting curves l c Located inside the sealing surface.

[0194] According to the aforementioned method, as shown in Figure 34, the second curved surface B is trimmed to reduce the obstruction of the pocket space by the venous artificial valve leaflets. When the valve is open (i.e., when the second curved surface B bulges towards the proximal end), as blood passes through the valve leaflets, a portion of the blood can enter the pocket space through the free edge 52 formed by the trimming. This allows vortices to form inside the pocket space even when the valve is open, further reducing the probability of thrombus formation, while not affecting the sealing performance when the valve is closed (i.e., when the second curved surface B bulges towards the distal end).

[0195] In one possible embodiment, as shown in Figures 30 to 33, in a related embodiment of the bicuspid valve, the mating portion is a second artificial venous valve leaflet identical to the artificial venous valve leaflet.

[0196] Referring to Figure 30, the bicuspid valve includes a leaflet 5 and a second artificial vein leaflet 5a. The leaflet 5 and the second artificial vein leaflet 5a are obtained using the aforementioned design method for artificial vein leaflets. The fixed edge 51 of the leaflet 5 and the second artificial vein leaflet 5a is cut from the same cutting cylinder (i.e., cylinder 92). The sweep line l passing through the proximal endpoint of the spline curve 91 of the leaflet 5 and the artificial vein leaflet 5a... s (For example, a swept straight line or swept curve) is coplanar with the same radial plane of the same cut cylinder (i.e., cylinder 92), such as the upper end face of cylinder 92 on the left in Figure 30.

[0197] Specifically, in one or more embodiments of this specification, a cutting curve for designing a bicuspid valve is also provided. c The method includes: establishing a model, as shown in Figures 31 to 33, arranging the artificial venous valve leaflet (i.e., leaflet 5) and the second artificial venous valve leaflet 5a opposite each other on a certain axial section of the vein, wherein leaflet 5 and the second artificial venous valve leaflet 5a are identical, and the fixed edge 51 of the second curved surface B of leaflet 5 and the fixed edge 51 of the second curved surface B of the second artificial venous valve leaflet 5a are respectively attached to the inner wall of the vein; forming a sealing line or sealing surface between the two second curved surfaces B (for example, forming a sealing line or sealing surface between leaflet 5 and the second artificial venous valve leaflet 5a under normal conditions, or forming a sealing line or sealing surface when both leaflet 5 and the second artificial venous valve leaflet 5a bulge towards the distal end); trimming curve l c For sealing lines, or for cutting curves l c Located inside the sealing surface.

[0198] In designing the cutting curve for a bicuspid valve c In this method, since the sealing line or sealing surface is formed jointly by the artificial venous valve leaflet and the second artificial venous valve leaflet 5a, the second artificial venous valve leaflet 5a also has a cutting curve l. c According to the cutting curve l of the second artificial venous valve leaflet 5a c Cutting is performed to form the free edge 52 of the second artificial venous valve leaflet 5a, thereby obtaining two matching artificial venous valve leaflets that can seal each other, the second artificial venous valve leaflet 5a.

[0199] It should be recognized that those skilled in the art can understand the methods for obtaining the first surface A, the second surface B, and the trimming curve l. c The method of obtaining the above-mentioned features, as well as the other features described above, are applied to three-leaflet or other artificial valves. Therefore, the modified embodiments obtained by using the features of the embodiments in this specification are still within the scope of this specification.

[0200] In some embodiments, based on obtaining the leaflet 5 (or a pair of leaflets 5 and a second artificial venous leaflet 5a) according to the above method, the fixed edge 51 can be extended outward on both sides near the free edge 52 to form a first leaflet ear 53 and a second leaflet ear 54.

[0201] Furthermore, based on obtaining the leaflet 5 (or a pair of leaflets 5 and a second artificial venous leaflet 5a) according to the above method, the fixed edge 51 is extended outward away from the free edge 52 to form a positioning part 55.

[0202] The beneficial effects that the embodiments of this specification may bring include, but are not limited to: (1) the pocket-shaped support rod allows the stent to form a pocket-shaped space at the proximal end of the leaflet when it is opened, and the blood can effectively flow around in the pocket-shaped space to prevent blood stasis and thrombosis; (2) the pocket-shaped support rod has both deformation flexibility and good support, which prevents the stent from becoming unstable and folding inward when it is opened in the blood vessel; (3) the platform structure of the proximal support frame and the distal support frame in the stent can further strengthen the support of the artificial valve in the blood vessel and prevent the artificial valve from shifting under blood pressure; (4) the curved rod design in the leaflet fixing assembly can compensate for the deformation of the leaflet due to long-term use and effectively extend the service life of the valve; (5) the free edge of the leaflet The arc-shaped edge structure can prevent the formation of a large contact area with other leaflets under high pressure in the proximal segment, which could lead to separation between leaflets at the free edge and cause valve failure; (6) The sub-grid design in the proximal or distal support frame helps to increase the support force on the leaflet fixing components; (7) The V-shaped support foot design in the proximal support frame can be adjusted by adjusting the V-shaped opening of the V-shaped support foot to conveniently adjust the height of the point farthest from the central axis of the stent on the axial direction of the stent; (8) The point farthest from the central axis of the stent on the axial direction of the stent is offset or moved closer to the distal support frame, thereby ensuring that a large pocket space is reliably formed in the area near the proximal side of the leaflet, so that blood can flow freely. (9) The fixed edge obtained by cutting the cylinder has a shape that is compatible with the vein, which can anastomose the blood vessel and provide stable sealing performance after being fixed to the stent or the inner wall of the vein; (10) By selecting the cutting curve in the overlapping part and implementing the cutting to obtain the free edge, the working state of the leaflet can be judged in advance, and the obtained free edge can provide stable sealing performance in the working state; (11) The first segment of the three-segment design of the spline curve of the leaflet projection provides a large contact surface space between the leaflet and the mating part. The sealing surface and sealing line selected according to the contact surface space can provide sealing performance in the three-dimensional space; (12) The three segments of the spline curve of the leaflet projection The platform formed by the second segment in the design provides a large force-bearing surface between the leaflet and the blood, enabling a stable and rapid response based on blood pressure; (13) The third segment of the three-segment design of the spline curve of the leaflet projection can cooperate with the pocket-shaped support rod to form a pocket-shaped space; (14) The monotonic design of the spline curve of the leaflet projection avoids the formation of multiple partition areas on both sides of the valve, thus preventing blood stagnation; (15) The monotonic design of the spline curve of the leaflet projection is more prone to deformation and more likely to respond to blood pressure than a non-monotonic valve; (16) The spacing between the first straight line and the axis of the cylinder is designed to provide reserved space for the thickness of the leaflet, so that the leaflet and the mating part have a suitable fitting force.

[0203] It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects may be any one or a combination of the above, or any other possible beneficial effects. The above only lists the beneficial effects of some embodiments of this specification. More beneficial effects of the technical features of the embodiments of this specification can be found in the relevant descriptions of the corresponding embodiments, and will not be listed here one by one.

[0204] The basic concepts have been described above. It is obvious that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this specification by those skilled in the art. Such modifications, improvements, and corrections are taught in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

Claims

1. A stent for use in an artificial venous valve, characterized in that, The support frame comprises a proximal segment support frame, a leaflet fixing assembly, a bag-shaped support rod and a distal segment support frame; The leaflet fixing assembly is connected between the proximal segment support frame and the distal segment support frame, and is used for fixing a leaflet; The first end of the bag-shaped support rod is connected with the proximal segment support frame, and the second end is connected with the distal segment support frame; when the stent is expanded, the bag-shaped support rod can be convex in the radial direction of the stent to form a bag-shaped space on the proximal side of the leaflet fixing assembly.

2. The stent of claim 1, wherein The bag-shaped support rod comprises one or more than one S-shaped part connected in sequence, wherein the opening degree of at least one half-arc of at least one S-shaped part is greater than 0, and the opening degree of the half-arc is positively correlated with the included angle of the tangent of the two end points of the half-arc.

3. The stent defined in claims 1 or 2, wherein, The number of the bag-shaped support rods is two or more; the proximal end support frame comprises two or more V-shaped support feet corresponding to the two or more bag-shaped support rods; when the stent is expanded, the V-shaped opening degree of the V-shaped support feet is greater than a set threshold, and the V-shaped opening degree is positively correlated with the included angle of the two edges forming the V-shaped structure; The first end of the bag-shaped support rod is connected with the corresponding V-shaped support foot.

4. The stent of claim 3, wherein, When the stent is expanded, the length of the V-shaped support foot is less than the total length of the one or more than one S-shaped part connected in sequence in the bag-shaped support rod.

5. The stent defined in Claim 2, wherein, The S-shaped part of the bag-shaped support rod close to the second end of the bag-shaped support rod and the distal segment support frame is a straight rod; The total length of the one or more than one S-shaped part connected in sequence in the bag-shaped support rod is greater than the length of the straight rod.

6. The stent defined in claims 2 or 5, wherein, In the one or more than one S-shaped part connected in sequence in the bag-shaped support rod, the opening degree of the half-arc close to the distal segment support frame is greater than the opening degree of the half-arc close to the proximal segment support frame.

7. The stent defined in Claim 3, wherein, When the stent is expanded, the point on the bag-shaped support rod farthest from the center axis of the stent in the radial direction of the stent is at the same height as the V-shaped opening degree and / or length of the V-shaped support foot in the axial direction of the stent.

8. The stent defined in claims 1 or 7, wherein, When the stent is expanded, the point on the bag-shaped support rod farthest from the center axis of the stent in the radial direction of the stent is at the same height as the connection point of the leaflet fixing assembly and the proximal segment support frame in the axial direction of the stent. Alternatively, when the stent is expanded, the point on the bag-shaped support rod farthest from the center axis of the stent in the radial direction of the stent is closer to the distal segment support frame than the connection point of the leaflet fixing assembly and the proximal segment support frame in the axial direction of the stent.

9. The stent defined in Claim 1, wherein, The leaflet fixing assembly comprises two curved rods connected in a V-shaped structure; the connection point of the two curved rods is connected with the distal segment support frame, and the outer end points of the two curved rods respectively far away from the connection point are connected with the proximal segment support frame.

10. The stent of claim 9, wherein, The orthographic projection of the one or more than one bag-shaped support rod on the stent axial section is between the orthographic projection of the two curved rods on the stent axial section in the leaflet fixing assembly.

11. The stent defined in Claim 10, wherein, The number of the pocket-shaped support rods and the number of the leaflet fixing assemblies are respectively 2; two leaflet fixing assemblies are oppositely arranged in the circumferential direction of the stent; the orthographic projection of the first pocket-shaped support rod on the stent axial section is located in the middle of the orthographic projection of two curved rods in the first leaflet fixing assembly on the stent axial section, and the orthographic projection of the second pocket-shaped support rod on the stent axial section is located in the middle of the orthographic projection of two curved rods in the second leaflet fixing assembly on the stent axial section.

12. The stent defined in Claim 9, wherein, The curved rod has two or more arc-shaped sections. A reference plane is determined based on the connection points of two curved rods in a leaflet fixing assembly and the circumscribed endpoints of the two curved rods, and two or more arc-shaped sections of the curved rod in the leaflet fixing assembly are distributed on different sides of the reference plane.

13. The stent defined in Claim 12, wherein, Among the two or more arc-shaped sections of the curved rod, the arc-shaped section close to the distal segment support frame is located on the proximal side of the corresponding reference plane.

14. The stent defined in Claim 13, wherein, The curved rod has two arc-shaped sections, the arc-shaped section close to the distal segment support frame is located on the proximal side of the corresponding reference plane, and the arc-shaped section away from the distal segment support frame is located on the distal side of the reference plane.

15. The stent defined in Claim 9, wherein, The proximal segment support frame includes two or more proximal segment support grids. The circumscribed endpoints of the two curved rods in the leaflet fixing assembly are respectively connected with different proximal segment support grids.

16. The stent defined in Claim 15, wherein, The number of the proximal segment support grids and the number of the leaflet fixing assemblies are respectively 2; two leaflet fixing assemblies are oppositely arranged in the circumferential direction of the stent. The circumscribed endpoints of one curved rod in the first leaflet fixing assembly and the circumscribed endpoints of one curved rod in the second leaflet fixing assembly are both connected with the first positioning lug, and the first positioning lug is connected with the first proximal segment support grid; the circumscribed endpoints of the other curved rod in the first leaflet fixing assembly and the circumscribed endpoints of the other curved rod in the second leaflet fixing assembly are both connected with the second positioning lug, and the second positioning lug is connected with the second proximal segment support grid.

17. The stent defined in Claim 16, wherein, Two positioning holes distributed along the stent axial direction are respectively arranged on the first positioning lug and the second positioning lug, and the positioning holes are used for fixing the leaflet.

18. The stent defined in Claim 15, wherein, The proximal segment support grid has a V-shaped frame, and the V-shaped frame includes one or more triangular sub-grids and / or one or more quadrilateral sub-grids.

19. The stent defined in Claim 18, wherein, The V-shaped opening of the V-shaped frame is less than or equal to a set threshold value, and the V-shaped opening is positively correlated with the size of the included angle of the two edges forming the V-shaped structure.

20. The stent of claim 15, wherein, The distal segment support frame includes a first distal segment support grid and a second distal segment support grid. The first distal segment support grid is arranged below one curved rod in the first leaflet fixing assembly and one curved rod in the second leaflet fixing assembly. The second distal segment support grid is arranged below the other curved rod in the first leaflet fixing assembly and the other curved rod in the second leaflet fixing assembly. The first distal segment support grid and the second distal segment support grid are respectively fixed with a neointima, and the material of the neointima includes a high polymer material and / or a biological material.

21. The stent defined in Claim 20, wherein, The first distal segment support grid has a first W-shaped frame, and the second distal segment support grid has a second W-shaped frame. The connecting points of the two curved rods in the first leaflet fixing assembly are connected with one end of the first W-shaped frame and one end of the second W-shaped frame through a first positioning rod respectively; the connecting points of the two curved rods in the second leaflet fixing assembly are connected with the other end of the first W-shaped frame and the other end of the second W-shaped frame through a second positioning rod respectively. The W-shaped frame comprises one or more than one triangular sub-grid and / or one or more than one quadrilateral sub-grid.

22. The stent of claim 1, wherein, The proximal segment support frame is an inverted table body, and the distal segment support frame is a normal table body; the maximum radial dimension of the upper base of the inverted table body is greater than that of the lower base, and the maximum radial dimension of the upper base of the normal table body is less than that of the lower base.

23. The stent defined in Claim 22, wherein, The minimum upper base angle of the inverted table body is less than the minimum lower base angle of the normal table body.

24. The stent defined in claims 22 or 23, wherein, The minimum upper base angle of the inverted table body is taken from the value range of 75° to 85°, and the minimum lower base angle of the normal table body is taken from the value range of 80° to 87°.

25. The stent defined in claims 1 or 2, wherein, The number of the leaflet fixing assemblies is one, and the stent further comprises a fixing accessory; The fixing accessory is connected between the proximal segment support frame and the distal segment support frame, and is arranged opposite to the leaflet fixing assembly in the circumferential direction of the stent.

26. The stent defined in Claim 25, wherein, The leaflet fixing assembly comprises two curved rods connected in a V-shaped structure; the connecting points of the two curved rods are connected with the distal segment support frame, and the outer connecting end points of the two curved rods away from the connecting points are connected with the proximal segment support frame respectively; The fixing accessory has the same structure as the leaflet fixing assembly.

27. The stent defined in Claim 26, wherein, The normal projection of the pocket-shaped support rod in the stent axial section is located between the normal projections of the two curved rods in the leaflet fixing assembly in the stent axial section.

28. The stent of claim 1, wherein, The radial dimension of the rods constituting the leaflet fixing assembly is greater than the radial dimension of the rods constituting the remaining parts of the stent, so that the contact area per unit length of the rods constituting the leaflet fixing assembly with the blood vessel is greater than the contact area per unit length of the rods constituting the remaining parts with the blood vessel when the stent is expanded in the blood vessel; The remaining parts include one or more of the following parts: the proximal segment support frame, the pocket-shaped support rod, and the distal segment support frame.

29. The stent defined in Claim 28, wherein, The radial dimension of the rods constituting the leaflet fixing assembly is n times of the radial dimension of the rods constituting the remaining parts, where 1 < n ≤ 2.

30. The stent defined in Claim 28, wherein, The radial dimension of the rods constituting the leaflet fixing assembly is 0.1 mm to 0.5 mm.

31. An artificial venous valve, comprising: The artificial venous valve leaflet and the stent according to any one of claims 1 to 30 are included. The artificial venous valve leaflet is fixed on the leaflet fixing assembly.

32. The artificial venous valve of claim 31, wherein, The artificial venous valve leaflet has a fixed edge fixed on the two curved rods connected in a V-shaped structure in the leaflet fixing assembly, and a free edge located between the two ends of the fixed edge.

33. The artificial venous valve of claim 32, wherein, The artificial venous valve leaflet further has a first leaflet ear, a second leaflet ear, and a positioning part. The first leaflet ear and the second leaflet ear of the artificial venous valve leaflet are fixed at the first positioning ear and the second positioning ear respectively, and the positioning part of the artificial venous valve leaflet is fixed at the positioning rod connected by the connecting point of the two curved rods in the corresponding leaflet fixing assembly.

34. The artificial venous valve of claim 32, wherein, The free edge of the artificial venous valve leaflet is an arc-shaped edge protruding towards the fixed edge.

35. The artificial venous valve of claim 32, wherein, The fixed edge and the free edge form a boundary, and a leaflet curved surface is defined within the boundary; The free edge is configured to cooperate with a cooperating part to achieve opening and closing; The leaflet curved surface is configured such that its projection on at least one axial cross section of the vein is a spline curve, and the spline curve at least has a main body part; A coordinate system is established with the center of the radial plane of the vein where the artificial venous valve leaflet is located as the origin, the projection direction of the projection as the y-axis direction, the axial direction of the vein as the z-axis direction, and the direction orthogonal to the y-axis and the z-axis as the x-axis direction. In this coordinate system, the slope of the tangent line of any point on the main body part of the spline curve is a non-positive value or a non-negative value.

36. The artificial venous valve of claim 35, wherein, The spline curve further includes a starting part and / or an ending part connected to the main body part, and the starting part and / or the ending part is parallel to the z-axis direction.

37. The artificial venous valve of claim 35, wherein, The main body part of the spline curve sequentially includes a first segment extending along the axial direction of the vein, a second segment bending towards the outside of the radial direction of the vein, and a third segment bending towards the axial direction of the vein.

38. The artificial venous valve of claim 35, wherein, The fixed edge is a spatial curve, and the fixed edge is located on the side surface of a cylinder.

39. The artificial venous valve of claim 38, wherein, The diameter of the cylinder ranges from 2 mm to 15 mm, and the height of the cylinder ranges from 2 mm to 20 mm.

40. The artificial venous valve of claim 38, wherein, The first straight line formed by the movement of the end point of the proximal end of the spline curve along the projection direction has a spacing from the axis of the cylinder.

41. The artificial venous valve of claim 40, wherein, The spacing ranges from 0 mm to 1 mm.

42. The artificial venous valve of claim 34, wherein, The projection height of the arc-shaped edge on the axial cross section of the vein ranges from 0 mm to 10 mm, or the projection height of the arc-shaped edge on the axial cross section of the vein is 0-2 / 3 times the projection height of the artificial venous valve leaflet on the axial cross section of the vein.

43. The artificial venous valve of claim 35, wherein, The cooperating part is the free edge of another artificial venous valve leaflet, a second stent, or the inner wall of the vein.

44. The artificial venous valve of claim 35, wherein, The leaflet curved surface includes a first arc-shaped surface and a second arc-shaped surface with opposite protruding directions, the first arc-shaped surface is closer to the proximal end than the second arc-shaped surface, the first arc-shaped surface protrudes towards the distal end direction, and the second arc-shaped surface protrudes towards the proximal end direction.

45. The artificial venous valve of claim 44, wherein, The leaflet curved surface is configured to form a pocket-shaped space with the vein wall on the proximal side.

46. An artificial venous valve leaflet, comprising: It includes: a free edge, a fixed edge connected to both ends of the free edge to form a boundary, and a leaflet curved surface defined within the boundary; The fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein; The free edge is configured to cooperate with a cooperating part to achieve opening and closing; The leaflet curved surface is configured such that its projection on at least one axial cross section of the vein is a spline curve, and the spline curve at least includes a main body part; A coordinate system is established with the center of the radial plane of the vein where the artificial venous valve leaflet is located as the origin, the projection direction of the projection as the y-axis direction, the axial direction of the vein as the z-axis direction, and the direction orthogonal to the y-axis and z-axis as the x-axis direction. In the coordinate system, the slope of the tangent line of any point on the main body portion of the spline curve is a non-positive value or a non-negative value.

47. The artificial venous valve leaflet of claim 46, wherein, The spline curve further includes a starting portion and / or an ending portion connected to the main body portion, and the starting portion and / or the ending portion is parallel to the z-axis direction.

48. The artificial venous valve leaflet of claim 46, wherein, The main body portion of the spline curve sequentially includes a first segment extending along the axial direction of the vein, a second segment curved toward the outside of the radial direction of the vein, and a third segment curved toward the axial direction of the vein.

49. The artificial venous valve leaflet of claim 46, wherein, The fixed edge is a spatial curve, and the fixed edge is located on the side surface of a cylinder.

50. The artificial venous valve leaflet of claim 49, wherein, The diameter of the cylinder ranges from 2 mm to 15 mm, and the height of the cylinder ranges from 2 mm to 20 mm.

51. The artificial venous valve leaflet of claim 49, wherein, The first straight line formed by the movement of the end point of the proximal end of the spline curve along the projection direction has a spacing from the axis of the cylinder.

52. The artificial venous valve leaflet of claim 51, wherein, The spacing ranges from 0 mm to 1 mm.

53. The artificial venous valve leaflet of claim 46, wherein, The free edge is an arc-shaped edge protruding toward the fixed edge.

54. The artificial venous valve leaflet of claim 53, wherein, The projection height of the arc-shaped edge on the axial cross section of the vein ranges from 0 mm to 10 mm, or the projection height of the arc-shaped edge on the axial cross section of the vein is 0-2 / 3 times the projection height of the artificial venous valve leaflet on the axial cross section of the vein.

55. The artificial venous valve leaflet of claim 53, wherein, The matching portion is the free edge of another artificial venous valve leaflet, a second stent, or the inner wall of the vein.

56. The artificial venous valve leaflet of claim 46, wherein, The leaflet surface includes first and second arc-shaped surfaces with opposite protruding directions, the first arc-shaped surface is closer to the proximal end than the second arc-shaped surface, the first arc-shaped surface protrudes toward the distal end, and the second arc-shaped surface protrudes toward the proximal end.

57. The artificial venous valve leaflet of claim 56, wherein, The leaflet surface is configured to form a pocket-shaped space with the vein wall on the proximal side.

58. A method of designing an artificial venous valve leaflet, comprising: The artificial venous valve leaflet includes a free edge, a fixed edge connected to both ends of the free edge to form a boundary, and a leaflet surface defined in the boundary. The fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein. The free edge is configured to cooperate with a matching portion to achieve opening and closing. The design method includes: providing a spline curve; sweeping a sweep line along the spline curve to obtain a first surface; providing a cutting cylinder, making the sweep line passing through the proximal end point of the spline curve coplanar with a radial plane of the cutting cylinder, and making the first surface intersect with the side surface of the cutting cylinder; removing the part of the first surface located outside the cutting cylinder to obtain a second surface, and the cutting edge of the second surface by the cutting cylinder forms the fixed edge; wherein the leaflet surface is located in the second surface.

59. The method of designing a prosthetic venous valve leaflet according to claim 58, wherein, providing a cutting curve, and cutting the edge of the second surface except the fixed edge according to the cutting curve to form the free edge.

60. The method of designing a prosthetic venous valve leaflet according to claim 59, wherein, The second curve has a coincident area with the mating portion when the fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein and the second curve is bulged towards the distal end direction, and the cutting curve is determined based on the edge of the coincident area or located in the coincident area.

61. The method of designing a prosthetic venous valve leaflet according to claim 59, wherein, The cutting curve is configured to keep the free edge formed by the cutting curve adhered to the mating portion when the fixed edge is configured to be directly or indirectly fixed to the inner wall of the vein and the second curve is bulged towards the distal end direction.

62. The method of designing a prosthetic venous valve leaflet according to claim 59, wherein, The method for providing the cutting curve comprises: determining the mating portion; establishing a model to make the fixed edge of the second curve adhere to the vein and make the edge of the second curve other than the fixed edge adhere to the mating portion, and form a sealing line or a sealing surface between the second curve and the mating portion; the cutting curve is the sealing line or the cutting curve is located in the sealing surface.

63. The method of designing a prosthetic venous valve leaflet according to claim 59, wherein, the mating portion is a second artificial venous valve leaflet which is the same as the artificial venous valve leaflet; The method for providing the cutting curve comprises: establishing a model to make the artificial venous valve leaflet and the second artificial venous valve leaflet oppositely arranged relative to the axial cross section of the vein, and make the fixed edge of the second curve of the artificial venous valve leaflet and the fixed edge of the second curve of the second artificial venous valve leaflet respectively adhere to the inner wall of the vein, and form a sealing line or a sealing surface between the two second curves; the cutting curve is the sealing line or the cutting curve is located in the sealing surface.

64. The method of designing a prosthetic venous valve leaflet according to claim 59, wherein, The fixed edge extends outward on both sides near the free edge to form a first valve leaflet ear and a second valve leaflet ear.

65. The method of designing a prosthetic venous valve leaflet according to claim 59, wherein, The fixed edge extends outward away from the free edge to form a positioning portion.

66. The method of designing a prosthetic venous valve leaflet of claim 58, wherein, The spline curve has at least a main part; A coordinate system is established with the center of the radial plane of the vein where the artificial venous valve leaflet is located as the origin, the direction of the scan line passing through the proximal end endpoint of the spline curve as the y-axis direction, the axial direction of the vein as the z-axis direction, and the direction orthogonal to the y-axis and the z-axis as the x-axis direction. In the coordinate system, the slope of the tangent line of any point on the main part of the spline curve is a non-positive value or a non-negative value.

67. The artificial venous valve of claim 58, wherein, The spline curve further comprises a starting part and / or an ending part connected to the main part, and the starting part and / or the ending part is parallel to the z-axis direction.

68. An artificial venous valve leaflet, comprising: Obtained by the design method of the artificial venous valve leaflet according to any one of claims 58 to 67.

69. An artificial venous valve leaflet set, comprising: The artificial venous valve leaflet comprises two mirror image arranged artificial venous valve leaflets according to any one of claims 46-57 or 68; wherein the free edges of the two artificial venous valve leaflets are operatively adhered to each other.

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