WO2024077769A1

WO2024077769A1 - Valve seat structure and bioprosthetic heart valve

Info

Publication number: WO2024077769A1
Application number: PCT/CN2022/140290
Authority: WO
Inventors: 钟生平; 刘静; 靳永富
Original assignee: 金仕生物科技（常熟）有限公司
Priority date: 2022-10-13
Filing date: 2022-12-20
Publication date: 2024-04-18
Also published as: CN115553976A

Abstract

A valve seat structure and a bioprosthetic heart valve. The valve seat structure comprises a basic valve seat (10), wherein the basic valve seat (10) is of an annular structure having two free ends (101), and the basic valve seat (10) is expandable to have a larger diameter when the basic valve seat (10) is subjected to an expansion force from the inside to the outside; a flexible limiting member (20) is provided between the two free ends (101) of the basic valve seat (10), the flexible limiting member (20) is deployable when the basic valve seat (10) is expanded, and can limit continuous expansion of the basic valve seat (10) when the flexible limiting member (20) is completely deployed; and the flexible limiting member (20) has an overall cylindrical structure, and has two ends respectively fixedly arranged on the two free ends (101) of the basic valve seat (10) in a wrapping or sleeving manner. The structure arrangement of the flexible limiting member (20) allows the flexible limiting member (20) to form an integral structure with the basic valve seat (10) to the greatest extent, which reduces the influence of the arrangement of the flexible limiting member (20) on the integrity of the valve seat structure and also reduces the influence of the flexible limiting member (20) on a human body.

Description

A valve seat structure and biological valve

Technical Field

The present invention belongs to the technical field of biological valves, and in particular relates to a valve seat structure for a biological valve and a biological valve using the valve seat structure.

Background technique

Heart valve disease is a common complication of heart disease. Surgery can be used to replace or repair a diseased or damaged valve; in a traditional valve replacement procedure, the damaged leaflets are usually removed and the annulus is shaped to accept a replacement artificial valve.

An artificial heart valve usually includes a support structure arranged in the valve assembly. The support structure usually adopts a rigid structure and can be made of various biocompatible materials such as metal, plastic, ceramic, etc. The life of a biological valve is usually 10-20 years. After reaching the service life, the valve performance will decline. At this time, the patient is often too old and his body function is difficult to accept surgical operations. At present, an interventional valve is usually implanted in the original implanted biological valve. However, due to the influence of the original biological valve leaflets, the interventional valve frame, etc., the implanted interventional valve model must be at least one model smaller than the original biological valve, which will greatly reduce the overall blood flow channel area (valve orifice area) of the implanted biological valve, so that the postoperative cardiac hemodynamic condition cannot meet the patient's physical needs, resulting in poor postoperative effects.

Summary of the invention

The object of the present invention is to provide a valve seat structure and a biological valve to solve the problem that the effect of the biological valve becomes worse after the interventional valve is implanted.

The present invention is achieved through the following technical solutions:

A valve seat structure comprises a basic valve seat, wherein the basic valve seat is an annular structure with two free ends, and when the basic valve seat is subjected to an expansion force from inside to outside, the basic valve seat can expand to have a larger diameter;

A flexible restriction member is arranged between the two free ends of the basic valve seat. The flexible restriction member can be unfolded when the basic valve seat expands, and can limit the continued expansion of the basic valve seat when the flexible restriction member is fully unfolded; the flexible restriction member is an overall cylindrical structure, and its two ends are respectively fixedly covered or sleeved on the two free ends of the basic valve seat, so that the flexible restriction member can overall cover or sleeve the area between the two free ends of the basic valve seat, and when the flexible restriction member is in an unfolded state, an incompletely unfolded state and in the unfolding process, a part of the flexible restriction member is folded in a cylindrical shape on the outside of one of its fixed ends, and the folded part is always covered or sleeved on the outside of the basic valve seat.

As a further improvement of the above technical solution, a notch is provided on the flexible restriction member along its axial direction from one end to the other end, so that when the flexible restriction member is wrapped or sleeved on the basic petal seat, the outer edge of one side of the basic petal seat sleeved in the flexible restriction member can be exposed outside the flexible restriction member. At this time, the flexible restriction member is symmetrically or asymmetrically wrapped on both sides of this part of the basic petal seat.

As a further improvement of the above technical solution, the notch extends and passes through the other end of the flexible restriction member, so that the fixed end of the flexible restriction member is covered and arranged on both sides of the basic petal seat, and the folded part of the flexible restriction member is located on the outside of the fixed end of the flexible restriction member.

As a further improvement to the above technical solution, both ends of the flexible limiting member are fixedly connected to the basic petal seat by binding with wires; preferably, a notch is provided on the basic petal seat at the position where the flexible limiting member is fixed.

As a further improvement to the above technical solution, the flexible limiting member is not damaged under the expansion force of 5-10 atmospheres.

As a further improvement to the above technical solution, a notch is provided on the basic petal seat at a position where the flexible limiting member is fixed.

As a further improvement of the above technical solution, a fixing piece for fixing the two free ends is arranged on the basic petal seat between the two free ends, and the fixing piece limits the free movement of the two free ends so that the basic petal seat can form a complete annular structure in the initial state, and when the basic petal seat is subjected to an expansion force of a set size, the fixing piece is destroyed and fails and releases the restraint on the two free ends; preferably, the fixing piece does not fail under the expansion force of 0-2 atmospheres, and fails under the expansion force of 2-5 atmospheres.

As a further improvement to the above technical solution, the fixing member is a valve seat bag fixedly covering the surface of the butt joint or overlapped portion at two free ends of the basic valve seat.

As a further improvement to the above technical solution, the valve seat capsule is obtained by dissolving or melting the valve seat capsule material, coating it between the butt joints of the two free ends of the basic valve seat or on the surface of the overlapping parts of the two free ends, and solidifying it.

As a further improvement to the above technical solution, the valve seat capsule is made of a plastic material with elasticity, preferably silicone or polyurethane; preferably, the valve seat capsule is made of a plastic material with elasticity, preferably silicone or polyurethane.

As a further improvement of the above technical solution, the basic petal seat is a double-layer structural member formed by integrally rolling a metal plate or strip in a circular direction. The two layers of metal plates or strips are fixedly connected, and one or two layers of metal plates or strips are cut along their axial direction to form two free ends on the basic petal seat that are matched and overlapped.

On the other hand, the present invention also provides a biological valve using the valve seat structure.

Compared with the prior art, the present invention has the following beneficial effects:

The valve seat structure in the present invention adopts a non-closed structure, which can expand to the required specification diameter under the action of external force, so as to solve the limitation on the size of the interventional valve when implanting the interventional valve. At the same time, a flexible restriction member is set at the free end of the valve seat structure to limit the unlimited expansion of the valve seat structure under the expansion force, thereby ensuring the safety of the valve seat structure during use; and by setting the structure of the flexible restriction member, the flexible restriction member can form an integral structure with the basic valve seat to the greatest extent, reducing the impact of the setting of the flexible restriction member on the integrity of the valve seat structure, and at the same time, the flexible restriction member can always maintain a good fit with the basic valve seat in the undeployed state, the incompletely deployed state or during the deployment process, thereby further reducing the impact of the introduction and use of the flexible restriction member on the human body.

In this valve seat structure, a valve seat bag structure is arranged at the two free ends of the basic valve seat, so that a closed structure is formed between the two non-closed free ends, ensuring that the valve seat structure maintains good stability and integrity before expansion, further improving the practical performance of the valve seat structure; at the same time, the overlapping structure formed by the valve seat bag and the double-layer metal structure of the basic valve seat can form a good match, so that the valve seat structure has better elastic performance and better integrity.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

FIG. 1 is a schematic structural diagram of an embodiment of a petal seat structure of the present invention.

FIG. 2 is a partial schematic diagram of point A in FIG. 1 .

FIG3 is a schematic structural diagram of an implementation scheme of a basic petal seat in the petal seat structure of the present invention.

FIG. 4 is a partial schematic diagram of point B in FIG. 2 .

FIG. 5 is a schematic structural diagram of another embodiment of the basic petal seat in the petal seat structure of the present invention.

FIG. 6 is a schematic diagram of the connection structure between the flexible limiting member and the basic petal seat in the petal seat structure of the present invention.

FIG. 7 is a schematic diagram of the valve seat capsule structure in the valve seat structure of the present invention.

Wherein: 10, basic petal seat, 101, free end, 102, notch;

20. flexible limiting member, 201. fixed end, 202. notch, 203. folded portion;

30. Petal seat capsule.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

As a component of a biological valve, the valve seat structure meets the conventional functional properties and performance requirements of biological valves. However, when a conventional biological valve needs to be implanted into an interventional valve, the valve seat structure is deformed due to the difference in the valve seat structure, resulting in the implanted interventional valve being one size smaller than the previously implanted biological valve, thereby reducing the blood flow channel area after the interventional valve is implanted. To address this issue, the valve seat structure is set as an expandable structure, so that when the interventional valve is implanted, a balloon can be used to expand the valve seat structure in the original biological valve to increase the inner diameter of the valve seat structure, and the size of the re-implanted interventional valve can be increased.

However, in actual operation, the force exerted by the balloon when expanding the surgical valve seat is often large. When the valve seat structure is expanded, if the size of the valve seat structure is not effectively restricted, it may cause serious damage to the native valve ring of the human body and even lead to life-threatening danger. Therefore, while designing the valve seat structure as an expandable structure, it is necessary and a problem that needs to be solved to limit the size of the valve seat expansion diameter and avoid unlimited expansion.

At the same time, it should be taken into account that the valve seat structure, as a component of the biological valve, does not need to be expanded during the initial use stage after being implanted in the human body. During this stage, the valve seat structure, as a stable structural component, needs to provide stable support for the biological valve and needs to be able to maintain a stable shape and withstand the normal diastolic pressure of the human heart during operation without deformation. Therefore, high requirements are also placed on the stability of its structure before expansion. How to balance the contradiction between the stability and extensibility of the valve seat structure is also a problem that needs to be considered.

Moreover, as a device implanted in the human body, its structure also has some unusual requirements. For example, what kind of structure should be used in the valve seat structure to limit the expanding valve seat structure, and how to reduce the additional impact of the introduction and use of this restriction structure on human tissue during the expansion process. It is necessary to consider the coordination or fit relationship or performance between this restriction structure and the valve seat structure in the initial state and during the expansion process. These are also very important in the design of the valve seat structure.

Based on the above problems and actual needs, with reference to FIGS. 1 to 4 , the valve seat structure in this embodiment includes a basic valve seat 10, which is an annular structure with two free ends 101. Of course, the annular structure here is only limited to the angle that can form a closed loop structure in its overall structural form. In terms of specific structure, it can be a circular ring or a spiral in the circumferential direction, etc., which are conventional structures of other existing valve seats, see FIGS. 3 and 5 . When such a basic valve seat is subjected to an expansion force from the inside to the outside, such as the force provided by the balloon expansion, the basic valve seat can expand to have a larger diameter.

As a limit to the expansion size of the basic valve seat, a flexible limiter 20 is provided between the two free ends of the basic valve seat 10. The flexible limiter is an expandable structure when the basic valve seat expands, and when the flexible limiter is fully expanded, it can resist the expansion force brought by the balloon to limit the continued expansion of the basic valve seat. Here, in order to improve the integrity and fit between the flexible limiter and the basic valve seat in any state as mentioned above, the structure of the flexible limiter is designed. Specifically, referring to Figures 1, 2 and 6, the flexible restriction member 20 is designed as a cylindrical structure as a whole, which can be a closed cylinder or a partially open cylindrical structure. The two ends of the flexible restriction member 20 are respectively fixedly covered or sleeved on the two free ends 101 of the basic valve seat, so that the flexible restriction member forms a fitting structure with the basic valve seat at the two fixed ends 201. At this time, the flexible restriction member can cover or sleeve the area between the two free ends of the basic valve seat as a whole, and form a good covering fit with the basic valve seat; at the same time, the flexible restriction member 20 is a deformable structure, which deforms with the basic valve seat during the expansion of the basic valve seat. In order to control the degree of fit between it and the basic valve seat during the deformation process, the flexible restriction member is in the unexpanded state, the incompletely expanded state and the expansion process. A part of the flexible restriction member is kept in the form of a cylindrical folded structure on the outside of one of its fixed ends, so that the folded part 203 is always covered or sleeved on the outside of the basic valve seat. It can be known that the structure of the folded part 203 is a state of a flexible material when it is not expanded, based on existing technology or common sense. The outer side of a fixed end 201 mentioned here is relative to the other fixed end of the flexible limiting part and the basic petal seat. The outer side of the fixed end refers to the direction away from the other fixed end. Such a setting can facilitate the storage of the flexible limiting part in the initial state, so as to minimize the impact on the specifications and dimensions of the basic petal seat, and facilitate the flexible limiting part to be better unfolded, the stability of the unfolding process, and the shape after unfolding. Of course, the possibility of setting this folding structure in other directions, such as setting it in the direction of the other fixed end, is not ruled out. These are easily thought of based on the structure of this embodiment.

As a preferred embodiment, as shown in FIG. 2 , a notch 202 is provided on the flexible restricting member 20 along its axial direction from one end to the other end, so that when the flexible restricting member is covered or sleeved on the basic petal seat, the outer edge of one side of the basic petal seat 10 sleeved in the flexible restricting member can be exposed outside the flexible restricting member, and at this time, the flexible restricting member 20 is symmetrically or asymmetrically covered on both sides of the part of the basic petal seat relative to the basic petal seat 10. The purpose of adopting this structural form is to facilitate the installation of the flexible restricting member on the basic petal seat and ensure that the flexible restricting member can maintain a good folding shape after installation.

As a preferred embodiment, the notch 202 extends and passes through the other end of the flexible limiting member 20, so that the fixed end of the flexible limiting member 20 is wrapped around both sides of the base petal seat 10. At this time, the folded part of the flexible limiting member is located on the outside of the fixed end of the flexible limiting member, so as to further facilitate the installation and setting of the flexible limiting member.

Specifically, as a foldable component, the flexible limiting member 20 should be made of foldable flexible materials, such as fabrics, filaments, films and other inelastic or low-elastic materials. These materials are conventionally selected based on the existing technology.

The two ends of the flexible restriction member 20 are respectively tied and fixedly connected to the two free ends 101 of the basic valve seat by binding wires. A notch 102 is provided on the basic valve seat 10 at the position where the flexible restriction member is fixed. When the flexible restriction member is fixed, the flexible restriction member is tied and fixed at the notch position to reliably connect the flexible restriction member to the basic valve seat. Of course, other structures such as fixing holes can be provided on the basic valve seat as auxiliary structures for fixing the flexible restriction member.

The arc distance between the two fixed ends of the flexible restriction member 20 is the preset circumference of the expanded basic valve seat. The flexible restriction member itself and the connection force between the flexible restriction member and the basic valve seat should be able to withstand the expansion pressure of 5-10atm of the balloon without being damaged.

As a preferred embodiment, in order to enable the non-closed valve seat structure to maintain a stable structure before expansion, referring to FIG. 7 , in this embodiment, a fixed part for fixing and connecting the two free ends is provided between the two free ends 101 of the basic valve seat 10. The fixed part is used to limit the free movement of the two free ends, so that the basic valve seat can form a complete annular structure in the initial state, and has the characteristic that when the basic valve seat is subjected to an expansion force of a set size, the fixed part can be destroyed and fail, thereby releasing the restraint on the two free ends. It can be imagined that the fixed part here is a structural part with the above-mentioned function, and it can be used to connect the two free ends in an existing conventional structural form such as bundling and bonding. Generally, the fixed part should be able to withstand the expansion pressure of 0-2 atmospheres of the balloon without being destroyed, so that the basic valve seat can maintain good integrity and stability before expansion; it should be able to be destroyed and fail when subjected to an expansion force of 2-5 atmospheres, so as to achieve its role in the basic valve seat of the structure.

As a specific practicable structure, the solid part here can be a valve seat capsule 30 fixedly covered on the surface of the butt joint or overlapped part of the two free ends 101 of the basic valve seat 10, refer to Figure 7. The valve seat capsule 30 structure can be formed by dissolving or melting the raw material used for the valve seat capsule, and then coating it on the butt joint between the two free ends of the basic valve seat or the overlapped surface of the two free ends, and the valve seat capsule can be formed after solidification and molding; at this time, the valve seat capsule in a sleeve-shaped covering sleeve between the two free ends forms a fixed connection to the two free ends, and when the basic valve seat is subjected to the expansion force, the valve seat capsule is destroyed under the action of shear force, and the fixation and restriction of the two free ends can be released. The valve seat capsule 30 can be made of elastic plastic material, such as silicone, polyurethane, etc. The thickness of the valve seat capsule is controlled within the range of 0.02-0.18mm. Here, the valve seat capsule uses elastic material to stably connect the basic valve seat, so that it can have good fatigue resistance under the action of continuous diastolic force, thereby improving the performance and service life of the valve seat capsule.

As a preferred embodiment, referring to Figs. 3, 4 and 5, the basic petal seat 10 is a double-layer structure formed by rolling metal sheets or metal strips in an annular direction. The two layers of metal sheets or metal strips are fixedly connected by welding to form an overall annular structure to increase the overall elastic performance of the basic petal seat. One layer of metal sheet or strip is cut off, or two layers of metal sheets or strips are cut off at intervals to form two free ends 101 in a matching overlapping arrangement on the basic petal seat, so that the rolled double-layer structure can form a good match in the overall structure while forming an overlapping structure. The basic petal seat structure shown in Figs. 2 and 3 is a double-layer structure formed by rolling metal sheets. The two ends of the metal sheets are respectively located at the inner and outer sides of the annular structure and are arranged oppositely. At this time, the inner metal sheet is cut off at a certain distance from the end of the metal sheet to obtain a non-closed loop basic petal seat, and at this time, the two free ends of the basic petal seat form an overlapping matching structure of inner and outer single-layer metal sheets.

This embodiment is a biological valve, which adopts the valve seat structure in the above embodiment and can have the functions of the corresponding valve seat structure.

That is to say, as a more preferred embodiment, the biological valve can adopt a multi-layer valve seat structure with a circumferential spiral shape. The valve seat structure includes a basic valve seat, a flexible limiting member and a valve seat bag. The biological valve adopting this valve seat structure can achieve two working states A and B.

In working state A, it is the initial use state of the biological valve. In this use state, the valve seat bag fixes the two free ends of the basic valve seat, which meets the size and use requirements of the biological valve in the initial use state, and can withstand the normal diastolic force of the heart valve ring. In this use state, the basic valve seat can always maintain good integrity and stability; at this time, the flexible restriction piece is folded, curled and wrapped on the basic valve seat in this working state.

In the B working state, the valve seat structure in the biological valve is expanded and used. In this state, an interventional valve needs to be implanted in the biological valve. At this time, the biological valve can be expanded by a balloon. Under the expansion force of the balloon, the valve seat capsule is torn and damaged, and the restraint on the free end of the basic valve seat is released, so that the two free ends of the basic valve seat are relatively separated. In this process, the curled flexible restriction piece is gradually pulled apart, and the diameter size of the basic valve seat becomes larger until the flexible restriction piece is tensioned. The diameter size of the basic valve seat is restricted again by the flexible restriction piece to meet the implantation size requirements of the interventional valve; after the interventional valve is implanted, the interventional valve supports the basic valve seat in the expanded state, so that the flexible restriction piece is always in an open and tight state. Usually, according to the size requirements of the implanted interventional valve, the diameter of the basic valve seat in the B working state should be 1-4mm larger than the diameter in the A working state.

In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. used to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship commonly placed when the product of the invention is used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In addition, if the terms "horizontal" or "vertical" appear in the description of the present invention, it does not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

A valve seat structure, characterized in that it comprises a basic valve seat, wherein the basic valve seat is an annular structure with two free ends, and when the basic valve seat is subjected to an expansion force from inside to outside, the basic valve seat can expand to have a larger diameter;

A flexible restriction member is arranged between the two free ends of the basic valve seat. The flexible restriction member can be unfolded when the basic valve seat expands, and can limit the continued expansion of the basic valve seat when the flexible restriction member is fully unfolded; the flexible restriction member is an overall cylindrical structure, and its two ends are respectively fixedly covered or sleeved on the two free ends of the basic valve seat, so that the flexible restriction member can overall cover or sleeve the area between the two free ends of the basic valve seat, and when the flexible restriction member is in an unfolded state, an incompletely unfolded state and in the unfolding process, a part of the flexible restriction member is folded in a cylindrical shape on the outside of one of its fixed ends, and the folded part is always covered or sleeved on the outside of the basic valve seat.
The flap seat structure according to claim 1 is characterized in that a notch is provided on the flexible restriction member along its axial direction from one end to the other end, so that when the flexible restriction member is wrapped or sleeved on the basic flap seat, the outer edge of one side of the basic flap seat sleeved in the flexible restriction member can be exposed outside the flexible restriction member. At this time, the flexible restriction member is symmetrically or asymmetrically wrapped on both sides of this part of the basic flap seat.
The flap seat structure according to claim 2 is characterized in that the notch extends and passes through the other end of the flexible limiting member, so that the fixed end of the flexible limiting member is covered and arranged on both sides of the basic flap seat, and the folded part of the flexible limiting member is located on the outside of the fixed end of the flexible limiting member.
The valve seat structure according to claim 1 is characterized in that both ends of the flexible limiting member are fixedly connected to the basic valve seat by binding with wires; preferably, a notch is provided on the basic valve seat at the position where the flexible limiting member is fixed.
The valve seat structure according to any one of claims 1-4 is characterized in that the flexible limiting member is not damaged under the expansion force of 5-10 atmospheres.
The flap seat structure according to claim 1 is characterized in that a fixing piece for fixing the two free ends is provided on the basic flap seat between the two free ends thereof, the fixing piece limits the free movement of the two free ends so that the basic flap seat can form a complete annular structure in the initial state, and when the basic flap seat is subjected to an expansion force of a set magnitude, the fixing piece is destroyed and fails and releases the restraint on the two free ends; preferably, the fixing piece does not destroy under the expansion force of 0-2 atmospheres, and destroys and fails under the expansion force of 2-5 atmospheres.
The valve seat structure according to claim 6 is characterized in that the fixing part is a valve seat bag fixedly covering the surface of the docking part or the overlapping part of the two free ends of the basic valve seat.
The valve seat structure according to claim 7 is characterized in that the valve seat capsule is obtained by dissolving or melting the valve seat capsule material, coating it on the surface of the butt joint between the two free ends of the basic valve seat or the overlapping parts of the two free ends, and solidifying it; preferably, the valve seat capsule is made of elastic plastic material, preferably silicone or polyurethane.
The petal seat structure according to claim 1 or 6 is characterized in that the basic petal seat is a double-layer structural member formed by integrally rolling a metal plate or strip in a circular direction, the two layers of the metal plates or strips are fixedly connected, and one or two layers of the metal plates or strips are cut along their axial direction to form two free ends on the basic petal seat that are matched and overlapped.
A biological valve using the valve seat structure described in any one of claims 1 to 9.