CN116725738A

CN116725738A - Valve support and artificial heart valve

Info

Publication number: CN116725738A
Application number: CN202210210198.0A
Authority: CN
Inventors: 彭峰
Original assignee: Lifetech Scientific Shenzhen Co Ltd
Current assignee: Shenzhen Jianxin Medical Technology Co ltd
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2023-09-12

Abstract

The invention provides a valve support, which comprises a support main body, wherein the support main body is tubular in a natural expansion state, the support main body comprises a wave ring, the wave ring comprises two adjacent connecting rods, the two adjacent connecting rods are in bending connection to form a node, and the node comprises a hollow structure. The valve stent provided by the invention can improve the stress concentration phenomenon at the node of the valve stent, reduce the maximum stress at the node, and simultaneously reduce the influence on the radial supporting force of the valve stent, thereby improving the durability of the valve stent and reducing the risk of stent fracture.

Description

Valve support and artificial heart valve

Technical Field

The invention relates to the technical field of interventional medical instruments, in particular to a valve support and a prosthetic heart valve.

Background

At present, heart valve disease is one of common cardiovascular diseases, and the heart valve disease refers to disease of a valve of a mitral valve, a tricuspid valve, an aortic valve, a pulmonary valve, and the like, which occurs due to rheumatic fever, mucus degeneration, degenerative change, congenital malformation, ischemic necrosis, infection or trauma, and the like, and influences normal flow of blood flow, so that abnormal heart functions are caused, and finally, single-valve or multi-valve disease of heart failure is caused. Since 2002, cribier et al have succeeded in implanting a stent with a prosthetic valve into a diseased aortic valve site in a human body, and the patient's hemodynamics after surgery has been significantly improved, and the quality of life has been improved. Along with the continuous perfection of interventional instruments and the accumulation of relevant experience, the interventional heart valve stent starts to be applied to cases of aortic valves, pulmonary valves, mitral valves, tricuspid valves and the like which are not suitable for surgical operation, the number of completed cases is rapidly increasing, a plurality of clinical tests are also being tightened, and the results of the tests provide more evidence-based medical evidence for the application of the technology.

However, there are several problems and drawbacks to existing clinically used interventional prosthetic heart valve designs. During the movement of the interventional heart valve which is carried out in vitro and is changed along with the valve annulus after being implanted in vivo, the valve stent is easy to break under the action of excessive loading force or fatigue effect, and the main reason is that the valve stent is easy to generate serious stress concentration phenomenon at the breaking point in radial deformation. Stress concentration of a certain structure on the valve support can cause a steep increase phenomenon of stress at the position relative to a nearby area, once the steep increase stress value exceeds the material limit strength of the support, the position is broken, particularly after the valve support is implanted into a human body, if the valve support breaks under the action of fatigue effect, the failure of a prosthetic heart valve is caused, a secondary valve replacement operation can be needed, and the risk is extremely high. During radial deformation of the valve stent, stress concentration phenomenon mainly occurs at a node of bending connection between adjacent connecting rods of the valve stent, the node can bend and deform around the radial direction, so that the valve stent is compressed towards the radial direction, and the common breaking direction is that the node is torn around the radial axis. The failure of the valve stent at the nodes can result in a substantial reduction in the radial support force of the annulus against the valve, resulting in a change in the size and shape of the valve stent, and thus failure of the valve She Kaige. Since the maximum stress of the node in the radial deformation of the valve stent is proportional to the rod width of the position of the stress point of the node, in the prior art, the fracture caused by stress concentration is avoided by reducing the rod width of the node position of the stent, but the method also reduces the bending-resistant section coefficient of the stent around the axial direction, so that the radial supporting force of the deformation of the valve stent is reduced, and the risks of valve displacement and paravalvular leakage after implantation are increased. Therefore, how to improve the stress concentration phenomenon of the valve stent, thereby reducing the fracture risk of the valve stent and reducing the influence on the radial supporting force of the valve stent at the same time has become a problem to be solved urgently.

Disclosure of Invention

The invention aims to solve the technical problem of providing a valve support and a prosthetic heart valve aiming at the fracture defect caused by the stress concentration phenomenon of the valve support in the prior art.

The technical scheme adopted for solving the technical problems is as follows:

an embodiment of the invention provides a valve support, which comprises a support main body, wherein the support main body is tubular in a natural expansion state, the support main body comprises a wave ring, the wave ring comprises two adjacent connecting rods, the two adjacent connecting rods are in bending connection to form a node, and the node comprises a hollowed-out structure.

In an embodiment of the present invention, the hollowed-out structure penetrates through the inner and outer surfaces of the node.

In an embodiment of the present invention, the node includes a first node formed by converging two end points of the connecting rod and a second node formed by converging at least three end points of the connecting rod.

In an embodiment of the present invention, the first node includes a middle area, and the hollow structure is located in the middle area.

In an embodiment of the present invention, the interface between the first node and the two connecting rods forming the first node forms two interfaces, respectively, and the hollowed structure includes a hollowed line extending from one of the interfaces to the other interface.

In an embodiment of the invention, the hollowed-out line includes a curve or a broken line.

In an embodiment of the present invention, the hollowed-out line includes a hollowed-out curve, and the first node includes an inner layer surface and an outer layer surface opposite to each other along a bending radian of the first node, where the hollowed-out curve is located between the inner layer surface and the outer layer surface and is the same as the bending radian of the inner layer surface and the outer layer surface.

In an embodiment of the present invention, the hollowed-out line includes hollowed-out fold lines, where the hollowed-out fold lines include a plurality of segments connected end to end, and a midpoint of each segment intersects a curved surface where a neutral layer of the first node is located.

In an embodiment of the present invention, the boundary between the second node and the two connecting rods forming the node forms two interfaces, respectively, and the hollow structure at least includes a hollow line extending from one of the interfaces to two sides far away from the interface.

In an embodiment of the present invention, the hollowed-out line on the second node is located in a central area of the interface corresponding to the width of the connecting rod.

In an embodiment of the present invention, the hollowed-out wire includes an end portion and a main body portion connected to the end portion, and a maximum dimension of the end portion in a width direction of the hollowed-out wire is greater than a maximum dimension of a portion where the end portion is connected to the main body portion in the width direction of the hollowed-out wire.

In an embodiment of the present invention, the first node includes an inner layer surface and an outer layer surface opposite to each other along a bending arc thereof, and the hollowed-out structure includes a saw tooth structure located on the outer layer surface.

In an embodiment of the present invention, when the valve stent is compressed, two adjacent connecting rods forming a first node are parallel along an axial direction, the radian of the corresponding bending of the first node is pi, the width of the connecting rod is defined as w, the single tooth width of the sawtooth structure is d, and the number of single sawtooth at the first node is n, so that n and d satisfy: nd is less than or equal to pi w.

In an embodiment of the present invention, a length of the sawtooth structure along the bending radian direction is less than or equal to two thirds of a length of an arc edge where the outer layer surface is located.

In an embodiment of the present invention, a width of the connecting rod is defined as w, and a tooth depth of the sawtooth structure is less than or equal to w/10.

In an embodiment of the present invention, the support main body sequentially includes a first section and a middle section from an inflow end to an outflow end, and the hollow structure is disposed on a node of the middle section.

In an embodiment of the invention, the support main body further includes a second section near one side of the outflow end, and the hollow structure is disposed on a node of the second section.

In an embodiment of the present invention, the hollow structure is disposed on a node of the first section, and a node distribution density of the hollow structure disposed on the middle section is greater than a node distribution density of the hollow structure disposed on the first section.

In another aspect, the present invention also provides a prosthetic heart valve, including a valve holder as described above, the valve holder including a connection portion, the prosthetic heart valve further including a leaflet and a skirt, the leaflet including a fixed edge and a free edge, the fixed edge being secured to the connection portion, the free edge being openable and closable angularly, and the free edge being located within the valve holder, the skirt being disposed around the valve holder.

According to the valve support, the hollowed-out structure is arranged at the node, so that the stress concentration phenomenon at the node of the valve support can be improved, the maximum stress at the node is reduced, the durability of the valve support is improved, the risk of support fracture is reduced, the influence on the radial supporting force of the valve support is reduced, and valve displacement, failure or paravalvular leakage after implantation is prevented.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic illustration of the structure of a prosthetic heart valve in accordance with an embodiment of the present invention;

FIG. 2 is a schematic view of the structure of a valve stent according to an embodiment of the present invention;

FIG. 3 is an enlarged view at A in FIG. 2;

FIG. 4 is a schematic view of a valve stent (with skirts and leaflets omitted) according to an embodiment of the present invention after implantation in a human body;

FIG. 5 is a schematic view of an embodiment of the present invention with an annulus acting on the intermediate section;

FIG. 6 is a schematic illustration of the structure of the tubular structure of FIG. 2 being cut open for tiling when compressed in a radial direction;

FIG. 7a is an enlarged view at B in FIG. 6;

FIG. 7b is an enlarged view of a first node without a hollowed-out structure according to the prior art;

FIG. 8 is a schematic view of the first node of FIG. 7a in a naturally expanded state;

FIG. 9 is a schematic view of an interface S according to an embodiment of the invention;

FIG. 10 is a schematic illustration of a forced bending of a simply supported beam;

FIG. 11 is a schematic diagram of a first node according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of a first node according to another embodiment of the present invention;

FIG. 13 is a schematic view of a first node according to yet another embodiment of the present invention;

FIG. 14 is a schematic view of a first node according to yet another embodiment of the present invention;

FIG. 15 is a schematic view of a first node according to other embodiments of the present invention;

Fig. 16 is an enlarged view at C in fig. 6;

FIG. 17 is a schematic diagram of a saw tooth structure when the first node is fully compressed in a radial direction according to an embodiment of the present invention;

FIG. 18 is a schematic view of the saw tooth structure of the first node of FIG. 17 in a naturally expanded state;

FIG. 19 is a schematic view of the structure of a valve stent of other embodiments of the present invention;

FIG. 20 is a schematic view of a state of the other embodiments of the present invention after implantation into a human body;

figure 21 is a schematic view of the combination of multiple leaflets in accordance with an embodiment of the present invention.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit or scope of the invention, which is therefore not limited to the specific embodiments disclosed below.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

The prosthetic heart valve of the present invention may be a mitral valve, a tricuspid valve, a pulmonary valve, or an aortic valve. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

"axial direction" is understood in the present context to mean the direction along the tubular central axis of the valve holder, "circumferential direction" in the present context means the direction around the axial direction, "radial direction" in the present context means the radial direction along the tubular cross-sectional circle and "around the radial direction" in the present context means the direction around the radial direction.

As shown in fig. 1-2 in combination with fig. 21, the present invention provides a prosthetic heart valve 100 comprising a valve holder 10, a plurality of leaflets 20, and a skirt 30. Wherein the valve support 10 has a tubular structure, a plurality of valve leaflets 20 are uniformly distributed in the tubular structure of the valve support 10, and the skirt 30 is fixed on the valve support 10 and the valve leaflets 20 through sutures.

As shown in fig. 1-3 in combination with fig. 21, the valve stent 10 includes a stent body 11 and a connecting portion 12, the connecting portion 12 being for connecting the valve corners 23 to connect with the valve leaflets 20. The stent body 11 includes a plurality of wave rings connected in the axial direction, the wave rings provided in this embodiment are annular structures formed by connecting a plurality of wave rods end to end in sequence, the valve stent 10 is tubular in a naturally expanded state, the number of wave rings of one annular structure including single waves (waves of one cycle) can be set to 6-21, and in this embodiment, the wave rings of one annular structure including 18 single waves, as shown in fig. 6. The two adjacent ring-shaped wave rings can be directly or indirectly connected with each other along the axial direction, as shown in fig. 2 and 6, the three ring-shaped wave rings can be directly connected with each other along the axial direction, and it is understood that in other embodiments, two or more ring-shaped wave rings can be directly connected with each other along the axial direction, and the whole length of the bracket main body can meet the size requirement of the human tissue to be implanted.

The valve stent 10 is made of a material with shape memory, such as super-elastic nickel-titanium alloy or stainless steel material, and when the valve stent 10 is subjected to radial compressive force, the valve stent 10 can shrink inwards to deform to a compressed state, and when the radial compressive force is removed, the valve stent 10 can expand to a natural state under the action of the self elasticity of the valve stent, so that the valve stent is restored to a tubular structure. Taking an aortic valve as an example, as shown in fig. 2-5, the outer diameter of the valve support 10 is larger than the inner diameter (about 10% -20%) of the largest opening of the human valve annulus when in a natural state, and as shown in fig. 4, when the aortic valve is implanted into a human body, the position of the attached valve annulus 301 is in a slightly compressed state, and a certain radial supporting force is provided for the valve annulus 301; as the heart contracts to dilate, the valve ring compresses the aortic valve further to slightly deform the stent body when the radius of the valve ring decreases from the maximum opening; with the cyclic movement of the heart's contraction and relaxation, the stent body of the aortic valve cyclically changes between a slightly compressed state and a further compressed state (the prosthetic heart valve always provides some radial support force to ensure that the opening and closing of the leaflets is unaffected), as shown in fig. 4-5.

The valve stent 10 may be formed by laser cutting (cutting and spreading the shape memory alloy tubing (e.g., nitinol tubing) as shown in fig. 6), and then heat setting the shape memory alloy tubing.

As shown in fig. 2, the stent body 11 sequentially includes a first segment 11a, a middle segment 11b and a second segment 11c from an inflow end to an outflow end, wherein the region of the middle segment 11b is a position fitting the valve annulus, the first segment 11a is close to the inflow end side, the second segment 11c is close to the outflow end side, the arrow position in fig. 5 is a position where the aortic valve is clamped in the valve annulus, the arrow direction is a direction of pressing force of the valve annulus to press the artificial heart valve, in the aortic valve, the inflow end is an end close to the left ventricle (e.g., the lower end in fig. 4 and 5), and the outflow end is an end close to the aorta 303 (e.g., the upper end in fig. 4 and 5).

In other embodiments, the outer side of the skirt corresponding to the region of the second segment 11c further comprises a protrusion 15 to prevent the prosthetic heart valve from being displaced or slipped off towards the inflow end, further increasing the stability and tightness of the fixation of the aortic valve. Preferably, the hollow structure of the aortic valve stent is uniformly arranged along the circumferential direction, so that the aortic valve stent is uniformly compressed in the radial direction, and deflection of the aortic valve due to uneven stress is prevented.

Each wave ring comprises a plurality of connecting rods 111, and the connecting rods 111 are connected end to end in sequence, so that the single wave ring is in an annular structure. The two adjacent connecting rods 111 are in bending connection, a node 112 for bending deformation around the radial direction when the valve support 10 is compressed along the radial direction is formed at the bending position, the node 112 bends around the radial direction, so that the two adjacent connecting rods 111 are opened and closed by taking the node as a fulcrum to realize the bending of the node, and meanwhile, the whole valve support 10 can be further compressed or restored along the radial direction along with the change of an annulus after being implanted into a human body.

In one embodiment, the node located at the middle section 11b includes a hollow structure, where the hollow structure is hollow along the inside and outside of the tubular stent body 11, that is, the node penetrating the valve stent 10 is along the inside and outside of the tubular shape, the node located at the second section 11c may also be provided with a hollow structure, preferably, the node where the stent body 11 is connected with the connecting portion 12 is the second inner node 102, and the hollow structure on the node of the second section 11c may be only provided on the second inner node 102, so that there is a good transition between the stent body 11 and the connecting portion 12, so as to increase the fatigue resistance of the valve stent, reduce the fracture risk of the second inner node 102, and simultaneously maintain the radial supporting force of the second section 11c, to provide better support for the valve leaflet 20, so that the valve corner 23 of the valve leaflet 20 is better fixed on the connecting portion 12, and the valve She Shixiao is prevented.

Since the valve holder 10 has an outer diameter larger than the inner diameter of the largest opening of the human annulus when in the natural state, the intermediate section 11b of the prosthetic heart valve, which is in abutment with the annulus, is compressively deformed, irrespective of the systolic or diastolic state, so that a certain radial supporting force is provided to the annulus. The opening of the annulus becomes larger or smaller along with the contraction and expansion of the heart, and the valve support, which is used for directly compressing the area of the middle section 11b due to the fact that the annulus 301 is attached to the area of the middle section 11b, enables the middle section 11b to be compressed in the radial direction, and meanwhile extends to the first section 11a to be compressed in the radial direction, but the deformation amount of the middle section 11b caused by compression is larger than that of the first section 11a, and by arranging the hollowed-out structure on the node of the middle section 11b, the radial supporting force of the middle section 11b is smaller than that of the first section 11a, when the middle section 11b is extruded by the annulus 301, the difference between the deformation amount of the middle section 11b in the radial direction and the deformation amount of the first section 11a in the radial direction is further increased, so that the first section 11a is tilted relative to the middle section 11b, namely forms a gradient with the middle section 11b, and the first section 11a is in a miniature horn shape towards the inflow end direction, as shown in fig. 5. When blood is pumped out along the direction from the inflow end to the outflow end, the valve leaflet is impacted, and when the impact force is transmitted to the valve support or the radial supporting force for deformation of the valve support is reduced, the risk of displacement and paravalvular leakage of the artificial heart valve is caused; through setting up hollow out construction in interlude 11b department, can make the difference between the radial deflection of first section 11a and interlude 11b further grow to thereby make the relative interlude perk of first section form horn mouth formula structure, can be when reducing the risk of stress concentration, further reduce valve shift risk, thereby prevent the valve periphery and leak. Because the inflow end is located one side that the blood flows into, take the aortic valve as an example, when the first section of inflow end one side is relative the middle section perk thereby forms horn mouth formula structure, still can increase the area of left room outflow tract, do benefit to blood pump, can reduce the risk of left room outflow tract obstruction.

In other embodiments, a hollowed structure may be further disposed at a portion of the nodes of the first segment 11a, and the node distribution density of the hollow structure disposed on the middle segment 11b is greater than the node distribution density of the hollow structure disposed on the first segment, so that the radial supporting force between the middle segment 11b and the first segment 11a forms a difference value (i.e., the radial supporting force of the middle segment is smaller than the radial supporting force of the first segment, the radial supporting force can respectively perform a simulation test on each segment of the valve support in vitro to obtain the radial supporting force of each segment, and the test can be performed by using a technology known in the art, specifically, when each segment of the support main body is respectively subjected to a force along the radial direction, each segment of the support main body is deformed, so that each segment is changed in the radial direction, the radial supporting force of each support body can be represented by the difference of the radial force required when the sections of the support body have the same variation in the radial direction, in other words, when the middle section and the first section are subjected to the same radial extrusion force, the radial deformation of the middle section is larger than that of the first section), so that the difference between the radial deformation of the middle section 11b and the radial deformation of the first section 11a is further increased, and the first section 11a is tilted relative to the middle section 11b, namely, forms a gradient with the middle section 11b, so that the first section 11a is in a miniature horn mouth shape towards the inflow end direction, and the risk of shifting the artificial heart valve can be further reduced while stress concentration is reduced, thereby preventing perivalvular leakage.

As shown in fig. 2-7 a in conjunction with fig. 8, the node 112 includes a first node 1121 (outer node) and a second node 1122 (inner node), and a node formed by converging two connecting rod end points is defined as the first node 1121, and the node is only connected with two adjacent connecting rods 111 on the same wave ring; the node formed by converging the end points of at least three connecting rods is defined as a second node 1122, that is, the node is directly connected with the node of the adjacent wave ring (as shown in fig. 2) or indirectly connected with a certain node of the adjacent wave ring through an independent rod in addition to the connection of two adjacent connecting rods 111 on the same wave ring. In the present embodiment, the first node 1121 is located in the area of the first segment 11a and the second segment 11c, the second node 1122 is located in the area of the intermediate segment 11b, and the second node further includes a second inner node 102 formed between the second segment and the connection portion, which can be understood that the hollow structure provided in the first node may conform to the shape of the node and be provided in the intermediate area of the second node, which is not limited herein.

In the prior art, the first node 1121 is not provided with a hollow structure, as shown in fig. 7b, and at this time, the first node 1121 includes a neutral layer a, and for a structure with uniform distribution of the same material in thickness, the neutral layer is generally an intermediate layer.

In the present embodiment, the interface between the first node 1121 and the two adjacent links 111 forming the first node 1121 includes two interfaces S (S1 and S2), respectively, which are perpendicular to the length direction of the links 111, as shown in fig. 2-3 in conjunction with fig. 6-7 a.

The hollow structure 113 includes hollow lines, which are hollow curves or hollow folding lines penetrating along the inside and outside of the tubular stent body 11, as shown in fig. 2-7a in combination with fig. 11-14. The hollowed out line can improve the stress concentration phenomenon when the node is bent, and reduce the maximum stress on the node, so that the durability of the valve stent is improved, the risk of node fracture of the valve stent is reduced, the influence on the radial supporting force of the valve stent is reduced, and the valve is prevented from shifting, failing or paravalvular leakage after implantation.

In this embodiment, as shown in fig. 7a and fig. 8, the hollowed line is a hollowed curve, the hollowed structure 113 of the first node 1121 includes a hollowed curve that is disposed along the neutral layer a, that is, the hollowed curve is disposed along the middle layer, and the hollowed curve is parallel to the inner and outer layers of the first node 1121 and has the same bending radian, so as to halve the first node. In other embodiments, the hollowed-out structure may also be disposed along a middle area M of the rod, where the middle area M refers to: the first node is trisected in the width direction of the rod to form two side areas and a middle area M, in which a hollowed-out structure may be provided to prevent the width of one of the split first or second outer nodes from approaching the original width when not hollowed out, and thus the effect of reducing stress concentration cannot be achieved, and the middle area is generally located on the middle line of the middle area as shown in fig. 7 b.

The first node 1121 is curved and has an arcuate body comprising an inner arcuate surface 11213 and an outer arcuate surface 11214, with the inner and outer surfaces 11213, 11214 being disposed opposite each other along the arc of the first node 1121, as shown in fig. 7 a. The width of the hollowed-out curve in the middle area is defined as Deltaw, and the length of the hollowed-out curve is defined as the curve length from the interface S1 on one side of the first node 1121 to the interface S2 on the other side. As shown in fig. 7a in combination with fig. 8, a hollowed-out curve is set on the first node 1121, and the hollowed-out curve divides the first node 1121 into a first outer node 11211 (with a width of w 1) located at the inner side of the hollowed-out curve and a second outer node 11212 (with a width of w 2) located at the outer side of the hollowed-out curve, where the first outer node 11211 and the second outer node 11212 each include their corresponding neutral layers (as shown by dashed lines a1 and a2 in fig. 8), and the distances between the stress concentration points on the first outer node and the second outer node and their corresponding neutral layers are obviously reduced, as shown in fig. 8.

When the hollowed-out structure provided by the invention is a hollowed-out line, the stress concentration phenomenon at the node of the valve support is improved, the maximum stress at the node is reduced, and the influence on the radial supporting force of the valve support is reduced, so that the durability of the valve support can be improved, the fracture risk of the valve support is reduced, and the principle of reducing the stress concentration phenomenon while reducing the influence on the radial supporting force of the valve support (retaining most of the bending rigidity of the axial section) can be achieved as follows:

Taking an example of setting a hollowed-out curve on a certain first node provided in this embodiment, as shown in fig. 2-7a in combination with fig. 8-10, the hollowed-out structure 113 includes a hollowed-out curve with a uniform width Δw set at a position of a neutral layer a of a first node 1121 of the valve stent 10 (the neutral layer is located on a middle line of a middle area), where Δw is defined as a minimum width that can be cut, the length of the hollowed-out curve is a curve length from an interface S1 on one side of the first node 1121 to an interface S2 on the other side, where the curve length coincides with the neutral layer a, and the hollowed-out structure equally divides the first node, as shown in fig. 7 a. In other embodiments, the hollow structure may be disposed in the middle area M of the first node, and it may be understood that the hollow structure of the second node may also be disposed in the corresponding middle area.

In the material mechanics, for an elastically homogeneous material, the cross-section bending stiffness of the beam is EI, where E is the elastic modulus of the elastic material, I is the moment of inertia of the cross-section, which is a geometric quantity, commonly used to describe the cross-section resistanceBending resistance properties. In the present embodiment, as shown in fig. 3 and 9, when the link 111 is a long rod having a rectangular cross section, the moment of inertia I of the axial cross section of the valve holder is known from the moment of inertia equation of the rectangular cross section _z ＝wt ³ Moment of inertia I of radial section/12 _R ＝w ³ t/12。

Defining the axial section bending stiffness of the first node 1121 of the valve holder 10 before being hollowed out as B _z Then:

defining the radial section bending stiffness of the first node 1121 of the valve stent 10 before being hollowed out as B _R Then:

where E is the Young's modulus of the valve stent material, w is the width of the connecting rod 111, and t is the thickness of the valve stent 10, as shown in FIGS. 2-3 in combination with FIGS. 6-9;

1) The change before and after the axial section bending stiffness is engraved is analyzed as follows:

when the first node 1121 of the valve stent 10 is provided with a hollowed-out curve as shown in fig. 3, the bending rigidity of the axial section at the corresponding position is B' _z Then:

because the hollowed-out curve is a line, the width Deltaw is less than w, and the width Deltaw is less than w:

B′ _z ≈B _z

the change of the bending stiffness of the axial section before and after the hollowed-out operation can be reduced by controlling the ratio of the cutting width to the whole rod width, namely, when the delta w is smaller than the w, the radial supporting force provided by the first node 1121 is changed slightly, namely, the hollowed-out structure can improve the stress concentration phenomenon of the valve stent, so that the fracture risk of the valve stent is reduced, and meanwhile, compared with the situation that the stress concentration phenomenon is reduced by directly reducing the rod width, the influence on the radial supporting force of the valve can be reduced. Preferably, the dimension of the hollowed-out structure in the width direction of the connecting rod is less than or equal to 1/10 of the width of the connecting rod.

2) The change after the radial section bending stiffness is hollowed out is analyzed as follows:

when the first node 1121 of the valve support is provided with a hollowed-out curve as shown in fig. 3, the hollowed-out curve divides the first node 1121 into a first outer node 11211 and a second outer node 11212, and as shown in fig. 8, the width of the first outer node 11211 is w1, and the width of the second outer node 11212 is w2, the structure of the hollowed-out first node 1121 can be approximately regarded as a laminated beam structure of the first outer node 11211 and the second outer node 11212, and the radial section bending stiffness of the hollowed-out first outer node 11211 is defined as B' _R1 The radial section bending stiffness of the second outer node 11212 is B' _R2 The overall radial section bending stiffness is: b'. _R

B′ _R ＝B′ _R1 +B′ _R2

Since w=w1+w2+Δw, then w > w1+w2, and since Δw occupies a relatively small amount of w, then w≡w1+w2

Thus, it can be seen that:

w ³ ＞w ₁ ³ +w ₂ ³

in this embodiment, if the hollowed-out curve is arranged along the neutral layer, w1=w2≡w/2, at this time,

it can be seen that the bending stiffness of the hollowed radial section is greatly reduced, the first node 1121 becomes softer when bending around the radial direction, and the bending stiffness of the hollowed radial section is only one fourth of that before the hollowed radial section, so that the phenomenon of stress concentration at the first node 1121 is not easy to occur due to the reduction of the bending stiffness of the radial section.

3) The variation of the maximum stress applied before and after the first node 1121 is hollowed out is analyzed as follows:

as shown in fig. 7b in combination with fig. 9-10, during radial compressive deformation of the valve stent, the first node 1121 of the valve stent may be approximately seen as a simply supported beam with hinged ends, as shown in fig. 10.

Defining the maximum stress on the first node 1121 as delta when the valve stent 10 is not hollowed out _max Maximum stress:

wherein M is the bending moment of the simply supported beam; since the neutral layer a is a transition layer which is neither in tension nor in compression, the stress is almost equal to zero, the farther from the neutral layer, the greater the line strain, the greater the degree of bending, i.e., y _max As shown in fig. 9 (y corresponding to the maximum stress point when not hollowed out) _max ) The method comprises the steps of carrying out a first treatment on the surface of the I is the moment of inertia. It can be understood that the valve stent with the hollow structure can also obtain the above formula, which is different in that y corresponds to each _max Different.

According to the characteristics of the simply supported beams, in radial deformation of the valve stent 10, the angle change amount of the first node 1121 of the valve stent 10 in the deformation bending radian is defined as θ, as shown in fig. 8, then:

the method can obtain:

substituting M of equation (2) into equation (1) yields the maximum stress δ:

where θ is the angular variation of the first node 1121 in the deformation curvature, l is the distance between the two ends of the first node 1121, E is the young's modulus of the valve stent material, and w is the width of the connecting rod 111.

As can be seen from equation (3), the maximum stress on the first node 1121 is proportional to the width w of the link 111.

In this embodiment, after the first node 1121 is divided into the first external node 11211 and the second external node 11212 along the hollow curve of the neutral layer, when the hollow curve is set along the neutral layer, w1=w2≡w/2, and the maximum stress δ' of the first node with the hollow curve is defined, then:

δ′＝δ/2

i.e. the maximum stress at the first node is reduced by half after the hollowed-out curve is provided in the central layer, but the change in bending stiffness of the axial section (providing radial support force) is smaller. Similarly, the hollow curve is arranged in the middle area, and the reduction of the maximum stress on the first node is far greater than the reduction of the bending rigidity of the axial section.

Namely, the hollow structure 113 is arranged at the first node 1121, so that the influence on the radial supporting force of the valve support can be reduced when the hollow structure 113 is arranged at the first node 1121 so as to reduce stress concentration, compared with the method that the width of the first node 1121 is directly reduced. Since the reduction of the radial support force (provided by the bending stiffness of the axial section) of the deformation of the valve stent 10 increases the risk of valve displacement and paravalvular leakage after implantation, the hollowed-out structure 113 is arranged at the node, so that the stress concentration phenomenon of the valve stent 10 is improved, the cracking risk of the valve stent is reduced, the influence on the radial support force of the valve stent is reduced, and the valve displacement, failure or paravalvular leakage after implantation is prevented.

In summary, since the maximum stress of a node in radial deformation of a valve stent is proportional to the width of the stem at which it is located, stress concentration can be avoided by reducing the distance between the stress concentration point and its corresponding neutral layer. Although the fracture of the stent can be avoided by reducing the rod width at the node position of the valve stent, when the stress concentration reducing effect achieved by reducing the rod width at the node position of the valve stent is the same as that achieved by arranging the hollow structure, the bending-resistant section coefficient of the stent around the axial direction can be greatly reduced, so that the radial supporting force of the deformation of the valve stent is reduced, and the risks of valve displacement, failure and paravalvular leakage after implantation are increased. When the hollowed-out structure 113 is a hollowed-out line, the stress concentration phenomenon can be improved on the basis of keeping most of bending rigidity (providing radial supporting force) of the axial section, and the maximum stress on the first node 1121 is reduced, so that the durability of the valve stent is improved, and the risk of stent fracture is reduced.

In other embodiments, two hollowed-out curves may be further provided, the width of the valve support 10 is 0.2 mm-0.5 mm (Δw is as small as about 0.02mm, the ratio of Δw to w is 1/25-1/10), the two hollowed-out curves may trisect the radius direction of the bending radian of the first node 1121 to form three outer nodes, and meanwhile, the three outer nodes have respective corresponding neutral layers, so that the distance from the stress concentration point to the respective corresponding neutral layer is further reduced, the first node 1121 is softer than the non-hollowed-out node structure in the radial direction, the stress concentration phenomenon is further improved, and the maximum stress on the first node 1121 is reduced, as shown in fig. 11. It can be understood that the two hollowed-out curves can be arranged in the middle area at intervals, and the two hollowed-out curves are not overlapped and communicated when in actual hollowed-out.

In practical application, the ratio of Δw to w is 1/25-1/10, so that the hollowed-out structure is only compared with the condition of directly reducing the width of the rod, the stress concentration phenomenon of the valve support can be improved, so that the fracture risk of the valve support can be reduced, the influence on the radial supporting force of the valve support can be reduced, but the actual radial supporting force is still reduced, if the radial supporting force in the axial direction of the valve support is reduced as a whole, the risks of valve displacement and perivalvular leakage can be possibly increased, and the difference between the deformation amounts of the first section 11a and the middle section 11b in the radial direction is further increased by arranging the hollowed-out structure at the middle section 11b, so that the first section is tilted relative to the middle section to form a horn-shaped structure, the risk of stress concentration can be reduced, and the risk of valve displacement can be further reduced, so that perivalvular leakage is prevented; or the distribution density of the hollow structures arranged on the middle section 11b is larger than that of the hollow structures arranged on the first section, so that when the artificial heart valve is implanted in the annulus, the deformation difference between the middle section 11b and the first section 11a is increased, and the effects can be achieved.

In another embodiment, as shown in fig. 12, the hollowed-out line includes an end portion 1132 and a main body portion 1131, the end portion 1132 is located at two ends of the hollowed-out line, the main body portion 1131 is connected with the end portion 1132, and a maximum dimension of the end portion 1132 along the width direction of the hollowed-out line is greater than a maximum dimension of a portion (G portion shown in fig. 12) where the end portion 1132 is connected with the main body portion 1131 along the width direction of the hollowed-out line. The end 1132 may be a round hole or an arc hole with smooth transition. Since the first node 1121 is divided into two parts of the first outer node 11211 and the second outer node 11212 by the hollow structure 113 in the thickness direction of the connecting rod 111, at the same time, the cut hollow curve is easy to generate micro cracks at the edges left at the start and end of the hollow curve, and in the process of natural expansion and radial compression of the valve stent, the deformation of the first outer node 11211 and the second outer node 11212 may not be consistent, so that a peeling trend is generated at the two ends of the hollow curve, and the peeling force corresponding to the peeling trend easily causes the micro cracks to extend, further worsen, and even cause the breakage of the valve stent 10. The end portions 1132 are arranged at the two ends of the hollowed-out curve, so that cracks or fissures formed at the two ends of the main body portion by cutting can be removed, and no cracks exist between the two ends of the main body portion 1131 of the hollowed-out structure 113 and the first node, so that fracture risks caused by crack stripping possibly caused in the process that the valve support is bent at the node due to compression deformation are prevented.

In other embodiments, the hollowed-out curve may be set to be a hollowed-out curve in which the edges of the whole line of the hollowed-out curve are smoothly transited, as shown in fig. 13, the hollowed-out curve is a thick line with a narrow middle part and a wide two ends, that is, the curve part outside the end 1132 is not a curve with equal width, the width in the middle of the curve and the width at the two ends of the curve are transited gradually from narrow to wide, and the first node 1121 provided with the hollowed-out curve can reduce the influence on the radial supporting force of the valve stent, and can improve the stress concentration phenomenon and reduce the maximum stress on the first node 1121, thereby improving the durability of the stent and reducing the risk of stent fracture.

In still another embodiment, when the hollowed-out line is a hollowed-out broken line, the hollowed-out broken line includes a plurality of segments connected end to end, each segment intersects with the curved surface where the neutral layer a is located, as shown in fig. 14, preferably, the middle point of each segment intersects with the curved surface where the neutral layer a is located, and according to the theory of the hollowed-out curve, the hollowed-out broken line can also achieve the effect achieved by the hollowed-out curve. That is, the provision of the hollowed out line improves the stress concentration phenomenon and reduces the maximum stress on the first node 1121 on the basis of retaining the original bending stiffness (providing radial supporting force) of the axial section, thereby improving the durability of the valve stent and reducing the risk of stent fracture. As shown in fig. 14, the two ends of the hollowed-out broken line are also provided with end portions 1132 to remove the cracks or fissures formed by cutting the two edges of the main body portion, so that the connection between the two ends of the main body portion 1131 of the hollowed-out broken line and the first node 1121 is free from cracks, thereby preventing the fracture risk caused by the crack peeling possibly caused in the process of bending the node by the compression deformation of the valve support 10. It can be understood that the hollowed-out broken line can also be arranged in the middle area of the first node, and the hollowed-out line matched with the shape of the second node can also be arranged on the second node and is arranged in the middle area of the second node.

As shown in fig. 15, the hollowed-out structure may further include a discontinuous point set, where the point set is discontinuously disposed in the middle area, and with respect to the hollowed-out line, the effect on the radial supporting force may be further reduced, and the stress concentration phenomenon may be improved. It can be understood that a discontinuous point set can be set on the node of the first section, and a continuous hollow structure is set on the node of the middle section, so that when the artificial heart valve is subjected to radial extrusion force on the middle section (clamped into the annulus), the deformation difference between the first section and the middle section is increased, and the first section is tilted relative to the middle section, namely, forms a gradient with the middle section, so that the first section is in a miniature bell mouth shape towards the direction of the inflow end, and the hollow structures are all arranged in the middle area of the corresponding node.

As shown in fig. 16, the second node 1122 forms two interfaces (S3, S4) with the two connecting rods 111 on the same race forming the node, and the hollowed structure further includes hollowed lines L2 extending from one of the interfaces S3 to both sides away from the interface S3. In other embodiments, a hollowed line extending away from the interface S4 on both sides of the interface S4 is also provided at the other interface S4. Since the second node 1122 is a node connected to other nodes, the second node 1122 is directly connected to a node of an adjacent hoop or indirectly connected to a node of an adjacent hoop through an independent rod in addition to the two adjacent links 111 on the same hoop, and at this time, the second node 1122 further includes at least one interface S5 in addition to the interfaces S3 and S4, and a hollowed line may be provided at the interface.

In the present embodiment, the hollowed line of the second node 1122 is located on the center line of the width of the connecting rod 111 corresponding to each interface, or is located in the middle area of the second node, as shown in fig. 16.

In other embodiments, the first node 1121 comprises an inner layer face 11213 and an outer layer face 11214 opposing each other along a curvature thereof, and the hollowed out structure 113 comprises a saw tooth structure 1133 on the outer layer face 11214. Wherein the saw teeth are one or more of triangular, trapezoidal, rectangular or circular arc. When the valve stent 10 is fully compressed in the radial direction, two adjacent connecting rods 111 forming a first node 1121 are axially parallel, the radian of the corresponding bending of the first node 1121 is pi, the width of the connecting rod 111 is w, the single tooth width of the sawtooth structure 1133 is d, and the number of single sawteeth at the first node 1121 is n, so that n and d satisfy the following conditions: nd is less than or equal to pi w. While the tooth width of the sawtooth structures 1133 may be set to the minimum width of the cutting path during cutting, the tooth depth h of the sawtooth structures 1133 may be set to be less than or equal to w/10, as shown in fig. 17.

In one embodiment, when the length of the sawtooth structure 1133 along the whole bending radian direction is equal to two thirds of the length of the arc edge where the outer layer surface 11214 is located, the sawtooth structure 1133 is symmetrically arranged at two sides of the first node 1121 along the axial direction, the length of the sawtooth structure 1133 hollowed out at one side is one third of the length of the arc edge of the outer layer surface 11214, as shown in fig. 17, the hollowed sawtooth structure 1133 is arranged from the interface towards the direction of the first node 1121, and is the state of the connecting rod 111 after the valve support is radially compressed. When the valve stent 10 is in the natural expanded state, the valve stent naturally expands to a maximally expandable position (natural expanded state), as the gaps between the individual teeth of the tooth structure 1133 squeeze out until they become absent, the gaps are closed by contact between the teeth, as shown in fig. 18. During the delivery of the valve stent from the natural expanded state to the radially compressed and deformed state (as shown in fig. 18 to fig. 17) and implanted into the human body, the outer surface 11214 of the first node 1121 of the valve stent will open up the saw tooth notch, as shown in fig. 17, and the saw tooth structure 1133 can also improve the stress concentration phenomenon and reduce the maximum stress on the first node 1121, thereby improving the durability of the stent and reducing the risk of stent fracture. In other embodiments, the outer layer surface 11214 of the first node 1121 may be provided at another position, so that a preferable effect is obtained and the arrangement may be made symmetrical in the axial direction.

In other embodiments, the valve stent 10 comprises a stent body 11, a connecting portion 12 and an auxiliary fixing portion 13, wherein the stent body 11 is used for interference fit with human tissue, and the stent body 11 sequentially comprises a first section 11a, a middle section 11b and a second section 11c from an inflow end to an outflow end, wherein the area of the middle section 11b is a position for fitting an annulus, as shown in fig. 19-20. The node that support main part and 11 are connected with connecting portion 12 is second interior node 102, and hollow out construction on the second section 11c node sets up on second interior node 102 for there is good transition between support main part 11 and the connecting portion 12, with the fatigue resistance that increases the valve support, reduces the fracture risk of second interior node 102, makes the better fixing in connecting portion 12 of the lamella angle 23 of lamella 20, prevents lamella She Shixiao. Taking the aortic valve as an example, the auxiliary fixing portion may serve to auxiliary fix the aortic valve, such as the auxiliary fixing portion 13 in fig. 20 is located at the aortic inlet, and the connecting portion 12 corresponds to the sinus position.

As shown in fig. 1-2 in combination with fig. 21, the prosthetic heart valve 100 provided in this embodiment is provided with three leaflets 20 of identical shape and structure, the leaflets 20 comprising a fixed edge 21, a free edge 22 and a corner 23. The fixed edges 21 of the leaflets 20 are secured by sutures to the skirt 30 or the stent mesh at the inflow end of the valve stent 10, the free edges 22 are not secured by sutures, and the ends of adjacent free edges 22 near the inner side of the valve stent 10 are joined together and bent to form the valve corners 23. The valve leaflets 20 are fixed on the connecting part 12 of the valve support 10 through the valve corners 23, and the free edges 22 are connected with each other to equally divide the tubular inner cavity of the valve support 10 along the circumferential direction, so that the valve leaflets 20 are formed into a whole which can be opened and closed in an angle. When the leaflets 20 are opened, blood is allowed to flow from the inflow end to the outflow end of the prosthetic heart valve 100 (downward-upward direction shown in fig. 1), and when the leaflets 20 are closed, blood is prevented from flowing back from the outflow end to the inflow end of the prosthetic heart valve 100, thereby functioning as a one-way valve. The leaflet 20 can be selected from tissue materials that are biocompatible, such as: pig pericardium, cattle pericardium, horse pericardium, sheep pericardium, pig heart valve, etc., and polymer materials and tissue engineering materials can be used.

The prosthetic heart valve provided by the present embodiments can be placed in the body with a dedicated delivery device and can also be delivered to the patient's heart aortic annulus in a variety of ways to work in place of the native valve, such as surgical open chest surgery, small incision surgery, and percutaneous or transcatheter delivery through the patient's peripheral blood vessel.

In the present embodiment, as shown in fig. 1-2 in combination with fig. 21, a skirt 30 is provided around the stent body 11 of the valve stent 10, and the skirt 30 is fixed to the valve stent 10 and the leaflets 20 by sutures, the skirt 30 serving to fix the leaflets 20 on the one hand and to prevent blood from passing through an area other than a channel formed between the leaflets 20 on the other hand. The skirt 30 includes an inner skirt and an outer skirt, the inner skirt is disposed along the inner surface of the valve stent 10, the inner skirt may be made of a cylindrical cloth having the same shape and size as those of the inner surface of the inflow end of the valve stent 10 in the natural expansion state, the shape of the outflow end of the inner skirt may be trimmed according to the shape of the fixing edge of the leaflet 20, the shape of the inflow end of the inner skirt may be trimmed according to the shape of the inflow end of the valve stent 10 or may be directly disposed in a flat opening, the inflow end edge and the outflow end edge of the inner skirt are both fixed with the fixing edges 21 of the valve stent 10 and the leaflet 20 by sutures, the non-edge region is not fixed, the outer skirt is disposed along the outer surface of the valve stent 10 and is fixed on the valve stent 10 by sewing, and the inner skirt and the outer skirt are connected to the inflow end of the valve stent 10 by sutures. In other embodiments, the inner and outer skirts are joined and integrally formed at the inflow end of the valve stent 10.

The sewing of the skirt 30 is performed in the natural expanded state of the valve stent 10, and the skirt 30 keeps the surface tight without affecting the morphology of the valve stent 10 or without compressing the valve stent 10.

The inner skirt and the outer skirt may be made of the same or different materials, and the skirt 30 may be made of a polymer material, such as PET (polyethylene terephthalate), PTFE (polytetrafluoroethylene), PU (polyurethane), or a biological tissue material or a tissue engineering material.

Wherein, the suture is used for connecting and fixing the valve bracket 10, the valve leaflet 20 and the skirt 30, and the material of the suture can be selected from high polymer materials such as PET, PTFE, PU and the like. The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. The valve support is characterized by comprising a support main body, wherein the support main body is tubular in a natural expansion state, the support main body comprises a wave ring, the wave ring comprises two adjacent connecting rods, the two adjacent connecting rods are in bending connection to form a node, and the node comprises a hollow structure.

2. The valve stent of claim 1, wherein the hollowed-out structure extends through inner and outer surfaces of the node.

3. The valve stent of claim 1, wherein the nodes comprise a first node formed by the convergence of two link ends and a second node formed by the convergence of at least three link ends.

4. The valve stent of claim 3, wherein the first node comprises a middle region, and the hollowed-out structure is located in the middle region.

5. The valve stent of claim 4, wherein the interface between the first node and the two links forming the first node each form two interfaces, the hollowed out structure comprising a hollowed out line along one of the interfaces to the other of the interfaces.

6. The valve stent of claim 5, wherein the hollowed out line comprises a curve or a fold line.

7. The valve stent of claim 6, wherein the hollowed out wire comprises a hollowed out curve, the first node comprises an inner layer surface and an outer layer surface opposite each other along a curvature thereof, and the hollowed out curve is located intermediate the inner layer surface and the outer layer surface and has the same curvature as the inner and outer layer surfaces.

8. The valve stent of claim 6, wherein the hollowed out line comprises a hollowed out fold line comprising a plurality of segments connected end to end, a midpoint of each segment intersecting a curved surface where a neutral layer of the first node is located.

9. The valve stent of claim 3, wherein the interface between the second node and the two links forming the node each form two interfaces, and the hollowed structure comprises at least a hollowed line extending away from one of the interfaces on both sides of the interface.

10. The valve stent of claim 9, wherein the hollowed out line on the second node is located in a central region of the interface corresponding to the width of the connecting rod.

11. The valve stent of claim 5, wherein the hollowed out wire comprises an end portion and a body portion connected to the end portion, and wherein a largest dimension of the end portion along a width direction of the hollowed out wire is greater than a largest dimension of a portion of the end portion connected to the body portion along the width direction of the hollowed out wire.

12. The valve stent of claim 3, wherein the first node comprises inner and outer opposed surfaces along a curve thereof, and the hollowed out structure comprises a saw tooth structure on the outer surface.

13. The valve stent of claim 12, wherein when the valve stent is compressed, two adjacent links forming a first node are axially parallel, the first node is curved in an arc pi, the width of the links is defined as w, the single tooth width of the saw tooth structure is d, the number of single saw teeth at the first node is n, and then n and d satisfy: nd is less than or equal to pi w.

14. The valve stent of claim 12, wherein the length of the sawtooth structures along the direction of curvature is less than or equal to two-thirds of the length of the arcuate edge on which the outer surface is located.

15. The valve stent of claim 12, wherein the width of the link is defined as w and the tooth depth of the saw tooth structure is less than or equal to w/10.

16. The valve stent of claim 1, wherein the stent body comprises a first section and a middle section in sequence from an inflow end to an outflow end, and the hollow structure is arranged on a node of the middle section.

17. The valve stent of claim 16, wherein the stent body further comprises a second section adjacent to the outflow end, the hollowed-out structure being disposed on a node of the second section.

18. The valve stent of claim 16, wherein the hollowed-out structure is disposed on nodes of the first segment, and the hollowed-out structure disposed on the intermediate segment has a node distribution density greater than that of the nodes of the first segment on which the hollowed-out structure is disposed.

19. A prosthetic heart valve comprising the valve holder of any one of claims 1-18, the valve holder comprising a connecting portion, the prosthetic heart valve further comprising leaflets and a skirt, the leaflets comprising fixed edges and free edges, the fixed edges being secured to the connecting portion, the free edges being angularly openable and closable, and the free edges being located within the valve holder, the skirt being disposed about the valve holder.