CN110090094B - Prosthetic valve and method of manufacturing a prosthetic valve - Google Patents

Abstract

The present invention relates to prosthetic valves and methods of making prosthetic valves. The invention relates to a prosthetic valve comprising a leaflet assembly having at least one leaflet (3) connected to a support element (2), the leaflet having a free edge movable between a first position and a second position, wherein in the first position the free edge is curved away from a closing surface (700) to allow bodily fluids to flow through the valve; in a second position, the free edge abuts the closure surface to close the valve, and wherein the leaflets are capable of forming an engagement height of greater than 0.1mm along the length of the free edge in the absence of a pulsatile load on the valve. Such prosthetic valves can provide good performance over a long period of time and can be manufactured using a variety of materials suitable for the leaflets. The invention also relates to a leaflet assembly for use in a prosthetic valve, and a method of manufacturing a prosthetic valve, including manufacturing a leaflet assembly.

Description

Prosthetic valve and method of manufacturing a prosthetic valve

The present invention is a divisional application of the invention patent application "prosthetic valve and method of manufacturing prosthetic valve" filed on date 2015, 5 and 6 and filed under No. 201580023424.2 (international application No. PCT/EP 2015/059982).

Technical Field

The present invention relates to implantable medical devices, such as prosthetic valves, and more particularly to bilobed or tri-leaflet prosthetic heart valves, and methods of making the same.

Background

A typical native valve of mammals is the aortic valve, which is one of four heart valves. The aortic valve comprises three leaflets (also called cusps) connected to the aortic root, which acts as supporting elements for these leaflets. Each of the three leaflets of the aortic valve has a free edge and an edge that is connected to the aortic root in a half-moon fashion. When the valve is opened, the leaflets fall back into their sinuses without potentially occluding any of the tubular orifices. The hinge lines of adjacent leaflets meet horizontally at the sinotubular junction to form at least a portion of a commissure (comassure). The body of the leaflet is soft, expandable and thin to provide the desired flexibility despite its non-uniform thickness. The leaflets are slightly thicker towards their free edges. Its ventricular surface is the apposition area (also known as the meniscus (meniscus)) that occupies the full width along the free edge and spans about one-third of the leaflet depth. This is where the leaflets meet adjacent leaflets during valve closure. When the valve is in the closed position, the edges of the meniscus coapt or merge together, separating the blood in the left ventricular chamber of the heart from the blood in the aorta. For this type or corresponding types of valves, the highest mechanical stresses occur at the commissures during opening and closing, and mechanical stresses occur to a lesser extent at the free edges of the leaflets.

Prosthetic valves are implanted in the human or animal body and may be used, for example, as passive, one-way prosthetic valves in or near blood vessels. They may be completely preformed and implanted as such, or may be formed in situ using artificial and/or natural components necessary to form a functional prosthetic valve. Suitable prosthetic valves need to open and close easily in response to pressure differentials on either side of the valve, cause no or little non-physiologic turbulence in the blood flow, and avoid excessive regurgitation. Therefore, the loading conditions (both in magnitude and number of cycles) for cardiovascular products (e.g., heart valve prostheses) are highly demanding. Typically, heart valve leaflets can undergo over a billion cycles of loading during their life. Therefore, durability of the prosthetic valve (especially the moving leaflets) is an important requirement.

Any prosthetic valve should be able to withstand the actual mechanical loads on the commissures and leaflet free edges during valve surgery and preferably remain resistant to such cyclic loads for many years. For this reason, not only is the initial strength an important parameter, but the likelihood of (insignificant) production of a malformation when manufacturing the valve is also reduced.

Valves used in valve surgery today are typically bioprosthetic valves with leaflets made of biological tissue (often chemically treated bovine pericardium). This is an elastic material that performs quite well and is able to mimic a natural valve. Early failure is often encountered and is believed to be related to high stresses on the leaflet material after continued extension and contraction under pulsatile loading. Various synthetic materials and designs have been proposed as alternatives to the fabrication of prosthetic valve leaflets.

Valve prostheses (prosthesis) made of synthetic fibers are described, for example, in NL 1008349. Such valves comprise a support element with leaflets manufactured by winding reinforcing fibres around a mandrel in a particular direction corresponding to the stresses present in the leaflets. Since the fibers must be placed according to the maximum stress line, such valve prostheses are difficult to manufacture and use many wound layers to accommodate the stress, increasing mass and possibly compromising flexibility.

Similarly, US6726715 describes a leaflet for a heart valve comprising a flexible sheet with stress-relieving fibrous elements in line with predetermined stress lines in the leaflet during operation of the valve. The sheet material is typically PTFE or PVF, where high strength/high modulus fibers are used as reinforcing elements. Fibers such as carbon, aramid or polyethylene fibers such as

UHMWPE fibers.

WO2010/020660 describes the manufacture of a prosthetic valve from a uniform hollow braid, for example made of polyolefin fibres. The hollow braid is shaped to form a valve by placing it on a mold comprising a tubular member and a star member. By the subsequent application of heat and pressure, the hollow braid takes the shape of the mold and creates the different sections. Around the tubular part of the mould, the hollow braid forms a portion corresponding to the support element of the valve, while the star-shaped part of the mould provides a portion corresponding to the plurality of valve leaflets. Before removing the valve from the mold, the anterior and posterior sides of the valve prosthesis are trimmed. To prevent damage to the trimmed edges, the edges may be heat treated to fuse the yarns to one another, provided with stitches, or otherwise treated to mechanically stabilize the edges.

Heim et al, Materials and Manufacturing Processes,26: 1303-; it shows that woven polyester can be suitable for forming valve prostheses. The polyester yarn has stretch properties to enable the textile to mimic the natural elastic stretch of a human valve (elongation of about 15%), since its typical elongation at break is about 14-17%. To obtain good leaflet contact between leaflets in the closed position and limit stress during the operating cycle, applicants teach shaping the leaflets so that there is a substantial natural opening in the center of the valve, while under cardiac pulsatile load, creating sufficient coaptation over the entire length of the leaflet free edges to prevent or at least minimize regurgitation.

An implantable valve prosthesis is described in US2008/0200977, comprising a frame and at least one leaflet made of a synthetic biocompatible polymer. The leaflets are designed such that their movement helps prevent blood from pooling in the valve pockets, i.e., preventing thrombosis. Leaflets are typically formed by the following method: a solution of polymer, preferably a block polyurethane, is cast and then two slits are provided to define a free portion that can move unrestrictedly to an open position and a closed position in response to fluid flow.

A prosthetic heart valve is disclosed in US2003/0114924, which comprises a valve body and a plurality of leaflets, which are formed in one piece by molding silicone or polyurethane. The valve is molded to include a gap between free edges of the leaflets in a neutral (neutral) position, and the leaflets have a particular curvature along the free edges; such that under fluid flow loads the gap closes and the faces of the leaflets engage and form a junction region.

US2009/027039 describes an implantable prosthetic valve having at least one leaflet and an inhibitory member for temporarily preventing the leaflet from substantially moving from an open position to a closed position. The leaflets can be made of various materials, such as biomaterials or synthetic polymers, but are preferably thin metal membranes.

A venous valve having a tubular frame and a cover comprising a surface defining a reversibly closable opening and thus acting as a leaflet is disclosed in US 2005/0137681. The leaflets can have a variety of sizes and shapes, including arcuate edges, curved surfaces, concave structures, or include curved support structures to effectively close the valve and restrict retrograde fluid flow. The leaflets may be made of a biological or synthetic fluid impermeable material including ePTFE, PET, urethane and polyethylene.

WO2000/62714 discloses a heart valve prosthesis comprising a one-piece moulding and a plurality of leaflets made of silicone or polyurethane. In the neutral or resting position, the free edges of the leaflets converge to form an uneven gap therebetween. The free edges of the leaflets have scalloped edges (corrugations) to provide enough material at the center to seal against fluid flow upside down with minimal joining.

US4191218 discloses a fabric for use in vascular prostheses and heart valves, said fabric being woven from multifilament (polyester) yarns comprising filaments having a diameter of about 10 μm and heat-shrinking said fabric to produce 20-40 μm open pore spaces and an elongation of at least 10% in at least one direction. The fabric preferably has woven selvedges (selvedge) that form the free edges of the heart valve leaflets.

US2012/0172978 describes a prosthetic valve comprising leaflets made of a filter screen material having uniform pores of 15-60 μm and a thickness of 10-100 μm and being woven from, for example, polyester or polypropylene monofilaments. In response to the closing flow pressure, the leaflets can be pushed together to coapt at the outflow edge, producing a coaptation of 3-9 mm. The method of making such a valve comprises: the individual leaflets are formed separately from the screen material, attached together along attachment lines, and optionally attached to a sewing ring or sewing frame/stent.

US2005/177227 discloses a method of manufacturing a heart valve prosthesis, wherein a textile membrane (preferably made of polyester or PTFE) is shaped to form leaflets; this is achieved, for example, by the following method: the segments are cut and the geometry of the heart valve in the closed arterial position is replicated using a shaping member, followed by heat fixation.

Disclosure of Invention

The invention relates to a prosthetic valve (400) comprising a leaflet assembly having at least one leaflet (3) connected to a support element (2), the leaflet having a free edge (5) movable between a first position and a second position, wherein in the first position the free edge flexes away from a closing surface (700) to allow bodily fluids to flow through the valve; in the second position, the free edge abuts the closure surface to close the valve, and wherein the leaflets are capable of forming a coaptation height (coaptation height) along the length of the free edge of greater than 0.1mm in the absence of a pulsatile load on the valve.

The present invention is based, at least in part, on the recognition that: known prosthetic valves made from flexible sheet material, as in the case of natural valves, rely on substantial elongation (extension) of the sheet material from which the leaflets are made to provide adequate coaptation, which is the contact of the leaflets with the closing surface along their free edges to close the surface, and proper opening of the valve during the closing and opening cycles. Typically, the elongation must be as high as about 15% to provide adequate coaptation, especially at the center of the leaflet (which coincides with the center of the valve for an asymmetric cylindrical tri-leaflet configuration). This in turn means that the sheet material must meet stringent mechanical performance requirements to be able and durable to mimic the native leaflets. The applicant has realised that: especially in the natural environment, which is immunogenic and can cause neoplasms and other abnormal processes, it is difficult to combine large amounts of extension and durability. Based on this recognition, the applicant has designed a prosthetic valve in which the leaflets are able to abut the closing surface in the valve along their free edges over a certain minimum coaptation height, also in the neutral position, in the absence of a pulsating load on the valve. This coaptation height is in contrast to the prior art, where coaptation is typically only produced during actual pulsatile loading on the valve and thus relies on the elongation of the leaflet material and the dynamics of the process, rather than producing the valve itself that meets certain spatial constraints. In summary, this means that the material from which the leaflets are made must meet less stringent stretch requirements, and therefore the present prosthetic valve and method of making it can provide at least more freedom of use for the sheet material and provide the option of making a more durable prosthetic valve. Additional advantages include: a woven structure made of high strength, low elongation biocompatible fibers, and thus a thin flexible fabric (preferably a woven fabric) can be used to manufacture the prosthetic valve.

It should be noted that the invention does not exclude: after joining at some point along the free edge, there may be a small channel or other opening for a while, for example due to the dynamics of the pulsating process. The formation of wrinkles or other temporary defects in the sheet material does not interfere with the proper functioning of the valve, so long as the leaflets have a geometry that inherently allows the valve to close along the free edge length in the absence of pulsatile loading, i.e., leaflet extension is not required. In other words, one or more leaflets have a geometry that: in the absence of pulsating loads, a certain minimum coaptation area is possible, such area defined by the leaflet's free edge length and coaptation height abutting the closure surface, thereby preventing substantial regurgitation in the valve during actual use. This geometry also results in sufficient coaptation and effective valve closure under pulsatile loading during use, even if the free edge itself does not partially fully abut the closure surface locally.

The present invention also relates to leaflet assemblies for use in prosthetic valves, as further described herein. The invention also relates to methods of manufacturing prosthetic valves, including methods of manufacturing leaflet assemblies. More particularly, the present invention relates to a method of manufacturing a prosthetic valve comprising at least one leaflet attached to a support member, the leaflet having a free edge movable between a first position and a second position, wherein in the first position the free edge flexes away from a closing surface of the valve to allow bodily fluid to flow through the valve; in the second position, the free edge abuts the closure surface to close the valve, the method comprising:

-providing a sheet, and

-forming a leaflet assembly from the sheet, the leaflet assembly comprising at least one leaflet and a support element,

wherein forming the leaflet assembly comprises: shaping the leaflets to impart a geometry wherein the leaflets are capable of forming a coaptation height along the length of the free edge of greater than 0.1mm in the absence of a pulsatile load on the valve.

It should be noted that "forming the leaflet assembly from the sheet" may include the steps of: for example, folding the leaflets, cutting, shaping in a mold, assembling multiple pieces of sheet material, attaching by stitching, gluing, etc. … ….

Definition of

A prosthetic valve is a construction having at least one leaflet and a support member to which the leaflet is connected such that the leaflet can bend or twist to provide an open position and a closed position for the valve, and may optionally include a rigid or semi-rigid support (also referred to as a frame or stent).

The leaflet assembly is a combination of at least one leaflet and a corresponding support member in a generally tubular configuration, which may be made from multiple pieces of material joined together or from a single textile structure (e.g., a woven fabric). The leaflets are movable parts and are connected to a support element (also known as a graft or skirt) that collectively define a pocket that can be filled with fluid to close the valve.

A joint is generally a line or point along which two things are connected; in the anatomy of a native heart valve, the commissures are distinct areas of connection between two adjacent valve leaflets and their supporting vessel walls. In this application, commissures refer to the lines or areas of connection between the leaflets and the support element (in the case of a stentless valve), and between the leaflets and the stent and optionally the support element (for a stented valve) on the outflow side. In addition to the connections forming the commissures, there may be additional connections between the leaflets, support members and/or stent, for example to further define the shape of the leaflets.

The edge of the leaflet is a kind of edge.

Coaptation means that a leaflet abuts, contacts, or merges with a closing surface (e.g., another leaflet) to close the valve; the coaptation height refers to the height or length of coaptation measured from the free edge (i.e., toward the base of the leaflet) in the longitudinal direction of the valve.

The centerline of the leaflet is the hypothetical line from the free edge of the center of the valve to the lowest point of the bottom of the leaflet (i.e., by connecting with the support member to define the lowest point of the leaflet). In the case of an asymmetric valve having, for example, three leaflets, the centerline of the leaflet is the line from the contact or commissure points of the three free edges to the lowest point.

The bending height characterizes the bending of the valve leaflet as: the maximum orthogonal distance between the centerline and a line connecting the nadir and the free edge of the center of the valve.

The radius of curvature of the leaflet is the radius of the circle that best conforms to an orthogonal cross-section of the curved surface of the leaflet in the closed valve position.

An elastic material is a material that is capable of returning to its original shape after being deformed.

Applying (improse) a geometric representation on the object: the geometry of the object is established by the object generation, as opposed to the geometry that can be generated by an external force applied to the object after it has been generated.

The inflow side or bottom of the valve represents: the side of the valve where fluid enters when the valve is in the open position, the opposite side is referred to as the outflow or top side of the valve.

Running or extending something parallel to another thing means: both things extend mainly in the same direction.

The elongation at break of the sample is: the elongation of the sample recorded at the time of sample rupture, expressed as a percentage of the original length of the sample, under the applied load. For sheet materials, elongation at break is also commonly referred to as elongation at break or elongation at break.

A yarn is an elongate body of length much greater than its cross-sectional width, typically comprising a plurality of continuous and/or discontinuous filaments, which are preferably arranged substantially parallel to one another.

Adjacent representations are positionally closest or contiguous.

Selvedges are edges of woven structures, wherein threads running in a direction perpendicular to the edges of the structure do not extend out of the structure as free ends, but continue at the edges by returning into the structure. Selvedges are typically formed from fill yarns (also known as weft yarns) during the weaving process, but may be made using other techniques or from warp yarns.

Drawings

Fig. 1 schematically shows the various steps of forming a valve prosthesis by means of a method according to the invention.

Figure 2 schematically shows various views of a textile structure suitable for manufacturing a valve prosthesis according to the invention.

Figure 3 schematically shows the geometry applied according to the invention compared to the prior art.

Figure 4 schematically shows various steps in a variant of the method described in connection with figure 3.

Figure 5 shows schematically how the selvedge is woven on the edge perpendicular to the warp direction.

Fig. 6 schematically shows the various steps in another embodiment of the method according to the invention.

Detailed Description

In a first embodiment, at least one leaflet of the prosthetic valve is formed with a geometry so imposed: in the absence of pulsating loads, engagements with engagement heights of 1-15mm are possible. It has been found that such a height creates a suitable land area that is effective in preventing backflow of reverse fluid flow while allowing for a quick, sufficient opening of the fluid path. Preferably, the geometry of the leaflets is made such that the engagement height is at least 2mm, 3mm, 4mm or 5mm and at most 15mm, 13mm, 11mm, 10mm, 9mm, 8mm or 7mm, for example between 3-10mm, preferably 5-7 mm.

In another embodiment, the geometry applied to the leaflet comprises a convex surface (relative to fluid entering at the base of the valve) having a radius of curvature at the centerline of the leaflet of between 1-20mm, such as 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, or 20mm, preferably about 12 mm. The inventors believe that the applied convex geometry with this particular small radius (as opposed to the typical radius of known prosthetic valves of 50mm or more) results in less stress and distortion in the leaflet material and possibly less tension at the commissures. This geometry also results in a relatively large volume of the pocket defined by the leaflets and the support member, which pocket will be filled with fluid during closure. This may facilitate efficient re-emptying after opening, prevent e.g. blood from remaining in the bag and reduce the risk of thrombosis.

In another embodiment, the geometry of the applied leaflet comprises a curved convex surface, wherein the curved height of such curved surface at the leaflet centerline is greater than 1mm, preferably greater than 2mm, 3mm or 4mm, most preferably about 5 mm. The maximum value is inherently dependent on the outer dimensions of the valve itself, but is typically about 10-15mm, for example 10mm, 11mm, 12mm, 13mm, 14mm or 15 mm. The inventors believe that the applied convex geometry with this particular shape (as opposed to the typical height of the prior art valve of 0-1 mm) results in less stress in the leaflet material and possibly less tension at the commissures. It should be noted that the curvature of the leaflet surfaces may depend on the diameter of the valve, i.e., larger diameter valves may have correspondingly greater curvature.

In another embodiment, the leaflets are formed such that the free edges of the leaflets have a length that is in addition to the theoretical length required to close the valve (e.g., in the case of a generally cylindrical valve having at least two leaflets, the distance between the two ends of the free edges relative to the commissure through the center of the valve). To create a preferred engagement height of at least 1mm or at least 3mm along the leaflet free edge length, applicants have found that it is advantageous to create additional free edge length (as opposed to conventional designs of pericardial material such as Carpentier-Edwards PERIMOUNT or textile designs such as Frederic Heim's design described above). This extra length can be generated in different ways. For example, in the case of a generally cylindrical valve of radius R and having three equally sized leaflets connected to the support element and evenly distributed between the commissures, the theoretical free edge length required is 2R. By providing the leaflet with a leaflet of at least the same size as the support member, its free edge length will be at least 2 π R/3; thereby producing an oversize (oversize) factor of at least about 1.05. A greater oversize can be obtained by designing the leaflets and optional support elements to be larger than the actual size of the valve or its holder during use. This can be accomplished, for example, by reducing the diameter of a prosthetic valve that includes a leaflet assembly and a stent having matching diameters by compressing the stent. The inventors note that US2005/177227 describes a cylindrical valve with 3 leaflets and indicates that the leaflet free edge length is equivalent to 2 times the length of the radius R and is therefore smaller than the corresponding part of the 2 rr/3 periphery, thus ensuring closure of the valve during diastole. In general, the inventors have found it advantageous to manufacture a valve in which the leaflet free edges have a total excess or extra length factor of at least 1.07, preferably at least 1.09, 1.11, 1.13 or 1.15, and preferably at most about 1.4, more preferably at most 1.3, relative to the theoretical length required to close the valve (e.g., relative to the minimum length required to bridge the distance between the commissures via the valve center). In other words, the free edge preferably has an extra length of at least 7%, more preferably at least 10% or 15%, and at most 40% or 30%.

In another embodiment, the additional length of the leaflet is generated by one or more method steps selected from the group consisting of: the sheet is pre-formed into a particular shape, for example by forming a trapezoid-like sheet (i.e. a form in which the portions corresponding to the leaflets form the wider lower half of the trapezoid and the portions corresponding to the support elements form the smaller upper half of the sheet), or a tapered or conical tubular material; such as by using claspers or compression stented valves to reduce the outer perimeter of the valve and alter the leaflet surfaces, and then finally securing the leaflets in the valve.

In another embodiment, a valve is manufactured that: wherein the leaflets are connected to the support element along commissures extending at least a length parallel to the flow of bodily fluids (i.e. parallel to the longitudinal axis of the valve) starting from the free edges. In this way, the stress on the joint is not concentrated at a point on the top edge as in conventional designs, but is distributed throughout the length, which may increase durability. If the valve comprises a rigid support or stent, the stent preferably has posts attached to the leaflet assembly as part of forming the commissures, thereby creating a stable and durable commissure. The commissures may extend throughout the height of the leaflet assembly or stent, but preferably have a length of 1-9mm or 1-6mm from the outflow side. It is clear that the length of the commissures can be proportional to the size (height) of the valve.

In another embodiment, wherein the sheet is an elastic material, the sheet has an elongation at break of 10% or less. One advantage of the method of the present invention is that low elongation sheets (i.e., materials with greatly reduced extensibility and much lower elongation to break) can also be used to form the leaflets of a valve prosthesis, which is a complete departure from the teachings of the prior art, which teach the use of materials that allow for elastic elongation of about 15% or more (which mimic the elongation properties of the native leaflet material). Less extension during use is believed to provide more durable leaflets and valves after implantation, not only from a mechanical perspective, but also because the extension of the object can cause collagen to spread over the object. Thus, the low elongation characteristic of the leaflets of the invention can reduce or minimize the kinetics of potential collagen or connective tissue overgrowth that would otherwise result in thickening and loss of mobility of the leaflets and may cause focal thrombosis or other neoplasms. In general, tissue overgrowth or fibrosis can lead to leaflet compression, which can lead to valve insufficiency. Preferably, in a surface made according to the present invention, the sheet has an elongation during use of less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or even 1%. Similarly, such sheets have an elongation at break of less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or even 1% when present at higher loads than during use as leaflets. Without wishing to be bound by any theory, the inventors believe that the application of a geometry to the leaflets that is able to provide a certain minimum coaptation height in the absence of load, obviously allows the use of sheets with low extensibility or high mechanical tensile resistance; i.e. a sheet having a high tensile modulus (also called young's modulus).

Albeit for example porcine intestinal submucosa (Cormatrix)^TM) Is a natural elastic sheet that can be used to create leaflets in a valve prosthesis (see, e.g., Zaidi et al, doi:10.1016/j.jtcvs.2014.02.081), but in one embodiment, the sheet is a woven structure comprising one or more elastic yarns having an elongation at break of 10% or less. As shown in some of the above-referenced patent publications, textile structures may also be suitable for use in the manufacture of leaflets. Textile materials are readily produced industrially on large and controllable scales. The low stretch advantage described above can be readily achieved by using yarns having an elongation at break of less than 10%, preferably less than 9%, 8%, 7%, 6% or 5%, preferably between 1-5%. Textile structures or fabrics can be made using techniques such as knitting, braiding, or weaving.

In another embodiment, the textile structure is a woven fabric made from one or more yarns or threads. The advantages of woven structures compared to, for example, knitted or braided structures are: by applying various weaving techniques, and by using various yarns as warp and fill yarns (or weft), the desired (non-or low-stretch) stretch properties and shape or form can be readily incorporated. The weave pattern has not been found to be particularly critical and those skilled in the art will be able to select a pattern to achieve the desired properties using some experimentation in conjunction with the selected yarns. Typically, woven fabrics having a common pattern (such as a plain, twill or basket weave pattern or a combination of different patterns) have been found to provide good performance.

One or more textile structures can be used as a sheet material to form the leaflets and leaflet assemblies. Suitable methods include: forming each leaflet and support element from a separate sheet-like sheet or woven structure, and then joining the individual sheets together; forming a plurality of leaflets from a woven structure and a plurality of support elements from individual woven structures, and then joining the two parts together; and forming a plurality of leaflets from a woven structure and a support member into a leaflet assembly. For example, a leaflet assembly having three leaflets and a support member can thus be made of 6, 4, 2, or 1 piece of textile (preferably woven fabric). Suitable methods of forming a leaflet assembly from a woven fabric include: a double weaving technique is applied which produces a multi-layer woven fabric, such as a so-called double-width fabric, which is open on one side, or a flattened tubular fabric, as described further below.

In another embodiment, the free edges of the leaflets are woven to selvedges. A woven or simple selvedge is a self-trimming edge of a woven textile structure. Selvedges avoid unraveling or fraying of the textile structure, but in direct contrast to other types of stabilized or trimmed edges, selvedges are the result of the actual weaving process, not of additional process steps (such as cutting, melting, sewing, or other processes for providing a stabilized edge). In woven textile structures, the selvage extends generally (but not necessarily) parallel to the warp threads and is formed by a fill yarn that loops back into the fabric around the last warp thread after exit. Selvedges are inherently created if the filler yarns are continuously supplied as in a weaving process, but can also be created in a non-weaving operation by tucking in the border (woven) ends of the filler yarns after each interweaving and cutting. The other method is as follows: additional yarns are introduced using a so-called leno-selvedge design which locks the outermost yarn ends at the edges of the fabric. By weaving the free edge as a selvedge, such a free edge is provided as an inherently mechanically stable edge without the use of additional process steps (e.g. melting or sewing). Additional process steps can complicate the valve manufacturing process as a whole and can also produce side effects such as changes in the mechanical properties of the yarn (e.g., increased stiffness, reduced abrasion resistance or reduced strength) after fusing loose yarn ends, or local thickening after edge stitching and reduced fabric flexibility. Nevertheless, such additional edge finishing may still be suitably used for edge stabilization of the woven fabric used to make the prosthetic valve; this is the case, for example, in the manufacture of continuous or endless woven fabrics that will later be cut to the desired length to form, for example, leaflets. Suitable examples of manufacturing the stabilized or trimmed edge are thermally cut woven fabrics, for example with a laser or with an electronic thermal cutter (also known as a hot knife, which allows for simultaneous cutting and melting of thermoplastic fiber fabrics in a controlled single step). Alternatively, yarns having a leno design may be included where the fabric is to be cut during weaving of the fabric.

In particular, it has been found to be advantageous to weave the textile structure as a multilayer structure comprising stacked layers, the layers preferably being interconnected by crossing over warp or filling yarns at desired locations, or by sewing or stitching after weaving. The applicant has realised that by applying a weaving process in which a woven textile structure comprising a plurality of superposed layers is produced (such a process is commonly referred to as a "double weaving" process and is commonly used to manufacture decorative fabrics), the support elements and the leaflets can be formed in the same textile structure in one weaving process, i.e. as different layers (or as segments in different layers) of such a textile structure. At the same time, the leaflets and support elements can achieve a common configuration in the structure or subsequent leaflet assembly that corresponds to the common configuration of the leaflets and support elements that are desired to be present in the final valve, and the commissures can also be obtained (at least in part) as a direct result of the weaving process. In such multilayer weaving, the longitudinal sides of the layers may be made in the form of open edges (usually with selvedges), or may be made as closed edges by joining the two layers at their edges. The width of the textile structure used to make the leaflet assembly will be on the order of centimeters, taking into account the size of the valve used in the bodily conduit (e.g., blood vessel or artery). For (industrial) woven fabric production, such dimensions may appear relatively small, but weaving methods, weaving patterns and machines suitable for such purpose are known in the art; such as those commonly referred to as narrow fabric weaves (systems) commonly used in the manufacture of tapes and belts. In such weaving equipment, the movement of each warp yarn is typically individually controllable to produce multiple layers, and various connections between the layers. Other information about this weaving method is available on the internet, for example, other information about double weaving is available in the files available via http:// www.cs.arizona.edu/patterns/weaving/webdocs/oprrgdw.

In one embodiment, a leaflet assembly is made from a flat piece of woven fabric by: the flat woven fabric is folded upon itself to form a tubular configuration by attaching the ends and creating additional connections between the two layers to define the leaflets and the support members.

In another embodiment, a single woven textile structure is produced by a double weaving process, resulting in a double woven fabric, for example a so-called double-width fabric, having two selvedges on the open side and a continuous folding line on the opposite closed side. In such a structure, one layer will form the support element and the other side will form the leaflets. The width of a layer is determined by the number of warp threads and the size of the warp threads, and two layers can be made to have the same or different widths or sizes by varying the respective number of warp threads in each layer. In such weaving processes, additional connections between layers may be made by crossing warp and/or fill yarns from one layer to another; this way the leaflets are at least partially defined, for example by connecting lines (which may be commissures). The spatial arrangement of the connecting wires will define the shape and size of the leaflets and their free edges, and the shape and size of the respective support elements. The leaflets can be made with larger dimensions than the corresponding support elements to create extra length of the free edge in the final valve by (locally) increasing the number of filling threads in the leaflet (the layer forming the leaflet) relative to the support elements of the leaflet.

Woven fabrics, including double fabrics as described above, may be produced in the form of unique length fabrics in a discontinuous process, such as on a conventional loom using warp threads attached to a beam (beam), or in the form of unique length fabrics in a continuous weaving operation by continuously feeding warp threads to the beam (beam). In the latter case, a continuous (or endless) web is produced, which can be cut to a desired length. In both cases, the resulting fabric piece can be made into a tubular structure by joining the fabric edges together with the warp (or cut) ends. The double woven fabric then results in a tubular structure in which the support elements will form the exterior and the leaflets are on the interior of the structure. In these embodiments, the warp threads run/extend parallel to the free edge, which is the selvedge of the fabric (similar to the upper edge of the support element).

In another embodiment, the woven textile structure is produced by a double weaving process that produces a seamless tubular fabric (also known as a flattened tubular fabric, a flat woven tubular fabric, or a hollow elongate fabric); because the woven textile structure is produced from continuous fill yarns that cross at each side edge from one set of warp yarns forming a first layer to another set of yarns forming another layer after each interweaving. It should be noted that in this case, a non-uniform total number of warp threads is used to exclude weaving errors, which is commonly referred to in the art as "error corrected tubular weaving".

In an alternative embodiment, endless beams (e.g., circular or triangular beams) are used to make the tubular woven fabric. Furthermore, in addition to single tube structures or single channel structures, multiple sets of warp and warp beams, specially designed endless warp beams (i.e., warp beams having connected ends, such as circular rings), and/or specific cross-pattern of yarns between layers or tubular structures may be used to make multi-channel or multi-layer tubular woven fabrics.

As also described above, the tubular fabric may be manufactured in a continuous weaving process or in a discontinuous manufacturing operation. In one embodiment of the invention, a method comprises: continuously woven, and the resulting endless (poly) tubular woven fabric is subsequently cut to the desired length. One cut end of the tube will form the free edge of the leaflet, but since the warp threads running/extending longitudinally in the tube will extend beyond the edge of the fabric after cutting, a finishing step is applied to stabilize the cut end. For both ends of the tubular structure, various finishing methods may be employed, preferably applying a heat treatment to a woven fabric made of thermoplastic polymer fibers. More preferably, the cutting and trimming are combined by using a hot knife or other hot cutting method. After trimming the cutting edge, the tube may be partially inverted, i.e., a portion of the tube will form a tube within the tube; by creating a connection between the tubes, the outer part will form the support element and the inner part will form one or more valve leaflets.

In another embodiment, the tubular woven fabric is made piece by a discontinuous weaving process. This has the following advantages: selvedges may be woven in the warp threads by not attaching the warp threads directly to the beam but by additional threads and/or bends, for example using the Pueblo-Navajo or warp selvedge system known in the art.

In one exemplary embodiment, a generally cylindrical tube is fabricated, optionally end-stabilized, and then partially inverted to produce a tube within the tube. In this case, the free edges of the leaflets will have substantially the same length as the respective support elements; this method has an extra length of about 5%. In a further embodiment, the tapered tube is manufactured, preferably by using a weaving process comprising gradually changing the number of threads in the woven fabric as described in US5800514 or US 2014/0135906. A length of tubular fabric is provided, having a first diameter at one end that is greater than, preferably at least 2% or 5% greater than, a second diameter at the opposite end, and which has a gradual transition from the first diameter to the second diameter, optionally stabilizing the ends. Then partially inverting the tube so that the inner tube is larger than the inner diameter of the outer tube; this means that the free edge of the leaflet will have more than 5% extra length. The multilayer tubular structure, described further below using the figures, can be processed in a similar manner to form a leaflet assembly for use in the methods of the invention.

Preferably, a textile structure comprising one or more elastic yarns having an elongation at break of 10% or less is used as a sheet for manufacturing the leaflet assembly. In further embodiments, the linear density of the elastic yarn is less than 120dtex, preferably the linear density of the elastic yarn is less than 100dtex, 80dtex, 60dtex, 50dtex, 40dtex, 30dtex, 20dtex or even 15dtex, preferably the linear density of the elastic yarn is at least 5dtex, 7dtex or 10 dtex; for example, the linear density of the elastic yarn is between 5dtex and 30dtex or between 7dtex and 15 dtex. The applicant has found that the use of a textile structure made of a thin yarn for the manufacture of a prosthetic valve can have an important advantage (note: although dtex is not a parameter representing the actual size or space length, it is in fact equivalent to the yarn diameter, since the density of most synthetic and natural materials used for the manufacture of yarns is about 1kg/dm³). In particular, the applicant has found that the use of such a thin yarn in a textile structure results in a very flexible fabric, enabling the leaflets to respond quickly under pulsating loads. The flexible leaflets can also be easily aligned with the support elements, creating a large effective aperture; and also causes less load at the joint. Moreover, applicants have found that the use of such a dilute yarn tends to have a woven structure with relatively low pore size and low permeability, particularly in the case of woven structures. This, together with the above mentioned reduced risk of thrombus formation, may contribute to good biocompatibility, efficacy and durability of the valve.

Similarly, the applicant has found that the following is advantageous for optimal performance: the thickness of the single-layer textile structure, preferably the woven fabric, is preferably at most 200 μm, 150 μm, 120 μm or 100 μm and at least 20 μm, 30 μm, 40 μm or 50 μm, for example a thickness of 40-150 μm, preferably 50-100 μm. In the case of woven fabrics, this layer thickness usually corresponds to a plain, basket or twill weave of (UHMWPE) filaments having a linear density in the warp and filling directions of 5-50 dtex.

In another embodiment, the textile structure comprises high performance polymer filaments, preferably having a high tensile strength or tenacity of at least 1Gpa and a high tensile modulus of at least 30 Gpa. Examples include carbon fibers, aramid fibers, aromatic polyester fibers, and ultrahigh molecular weight polyolefin fibers. Preferably, the textile structure comprises Ultra High Molecular Weight Polyethylene (UHMWPE) fibers, more preferably the textile structure comprises at least 80 mass% UHMWPE filaments having a tenacity of at least 2GPa, more preferably the warp and/or filling yarns essentially consist of UHMWPE filaments. Such multifilament yarns have been found to be ideally suited for use in woven fabrics for making leaflets and support elements of valve prostheses. UHMWPE yarns are durable, can be made to have desirable mechanical properties, and are commercially available in medical grades that are nearly non-immunogenic. In particular, it is preferred to use UHMWPE yarns having an Intrinsic Viscosity (IV) of at least 5dl/g, preferably at least 10dl/g, more preferably at least 15 dl/g. Preferably, the IV is at most 40dl/g, more preferably at most 30dl/g, even more preferably at most 25dl/g or 20 dl/g. IV is measured according to method PTC-179(Hercules Inc. Rev.1982, 4.29) in decalin at 135 ℃ with a dissolution time of 16 hours using DBPC as antioxidant in an amount of 2g/l solution, wherein the viscosities measured at different concentrations are extrapolated to zero concentration. Particularly preferred are gel spun UHMWPE yarns, typically having a young's modulus of 30GPa or 50 GPa. Preferably, the tenacity of the UHMWPE yarns is at least 1.2 GPa. Preferably, the yarn used according to the invention comprises at least 90 wt% UHMWPE yarns; most preferably, the yarns used according to the invention consist of UHMWPE yarns and have a young's modulus of at least 50 GPa. One preferred example of UHMWPE yarns is Dyneema, available from DSM in the netherlands

A yarn. This type of UHMWPE yarn is particularly preferred, being a low dtex version of the available medical grade yarn, which typically has an elongation at break of about 2-4%. The tensile strength (or strength) and tensile modulus (or modulus) of UHMWPE yarns were defined and determined at room temperature (i.e. about 20 ℃) on multifilament yarns specified in astm D885M using a fiber with a nominal gauge length of 500mm, a crosshead speed of 50%/minute and an Instron 2714 clamp type "Fibre Grip D56 5618C". Based on the measured stress-strain curve, the modulus was determined as a gradient between 0.3-1% strain. For the calculation of modulus and strength, the measured tension was divided by the titer (the titer was determined by weighing 10 meters of yarn); assuming a density of 0.97g/cm³The value in GPa is calculated. The ultra-high molecular weight polyethylene may be linear or branched, but preferably linear polyethylene is used, since very high tenacity and modulus can be obtained by drawing during the manufacture of the yarn. Linear polyethylene is herein understood to mean: polyethylene having less than 1 side chain per 100 carbon atoms, preferably less than 1 side chain per 300 carbon atoms; the side chain or branch typically contains at least 10 carbon atoms. The number of side chains in the UHMWPE sample was determined by FTlR on a compression molded film 2mm thick, where the absorption at 1375cm was quantified using a calibration curve based on NMR measurements (as in e.g. EP 0269151).

In another embodiment, typically where the sheet is formed from a semi-crystalline thermoplastic polymer, forming the leaflet assembly may further comprise: the shape of the leaflet is shaped by contacting the leaflet with a mould of the desired shape, optionally heating the mould to a temperature 3-60 ℃ (preferably 5-40 ℃) below the melting point of the sheet (i.e. the melting point of the polymer from which the sheet is made; polymer melting point determination please see ISO11357-3), optionally creep forming the sheet (i.e. changing its dimensions), and subjecting it to controlled relaxation and/or plastic stretching to conform to at least part of the mould. Such a thermoforming process is described, for example, in WO 2010/020660. With such an embodiment, the leaflet geometry can be further fine-tuned, for example to create a certain curvature or to meet certain clinical requirements.

In another embodiment, also typically where the sheet is formed substantially of a semi-crystalline polymer, the method further comprises the steps of: the permeability of the sheet is reduced by applying a coating or optionally arranging the sheet (preferably a woven structure) in a mould, heated to a temperature of 3-15 ℃ below the melting point of the polymer, and held at a temperature of 3-15 ℃ below the melting point of the polymer for 10 seconds-2 hours to impart local connections between adjacent filaments and/or yarns in the textile. Depending on the cross-section of the yarn and its arrangement in the textile structure (e.g. the type of weave), it may be advantageous to reduce the permeability of the textile structure. In such embodiments, the thermo-mechanical properties of the polymer from which the yarn is made can be used to improve the permeability of the textile structure.

In another embodiment, the prosthetic valve further comprises a stent (also referred to as a rigid load-bearing structure or frame) and the method further comprises: at least one leaflet and a support member are coupled to the stent. The attachment may be performed by using one or more attachment means, preferably by applying a suture. Suitable sutures have strength properties that enable a durable connection under load during use as a prosthetic valve. Preferably, the suture is made by using a suture material and yarns of similar strength to the yarns in the leaflets and the support member, more preferably by using yarns or sutures of a suitable size or linear density that contain at least 80% by mass of yarns of the same type as the yarns in the leaflets and the support member or that are made substantially of yarns of that type.

With respect to the use of rigid load bearing structures or braces, such braces typically comprise rigid members and are conventionally annular or cylindrical in shape. Suitable materials for fabricating the stent include rigid polymers, fiber reinforced polymers, metals and metal alloys, ceramics, and combinations thereof. Suitable rigid polymers include polyacetals, dextraplasts, polyurethanes, polyethylenes, polysulfones, polyethersulfones, polyarylsulfones, polyetheretherketones, and polyetherimides. Suitable metals include biocompatible metals, e.g. stainless steel, titanium, cobalt alloys, e.g. cobalt

(cobalt-chromium-nickel alloy) and MP35N (nickel-cobalt-chromium-molybdenum alloy), and

(nickel-titanium alloy). Furthermore, the scaffold may be produced from ceramic materials such as pyrolytic carbon, silicon carbide or metal carbides, hydroxyapatite and alumina. Suitable scaffolds may also be produced from carbon, such as graphite. Preferably, the stent is made at least in part of a superelastic or shape memory alloy, such as

(nickel-titanium alloy) which is useful as both a superelastic material and a shape memory alloy. Such a stent allows easy insertion of the valvular prosthesis into the desired location in the body. Prior to insertion, the self-expandable stent is brought to a first (relatively low) temperature at which it has a compact configuration. This compact configuration allows the stent (and the valve attached thereto) to be easily inserted into the body using minimally invasive surgery. After placement of the stent, the shape memory alloy will heat up and change phase due to body temperature, thereby changing its shape. For example, to

A phase transformation will occur between the austenite phase and the martensite phase. Thus, the stent will expand and thereby create a clamping force on the surrounding tissue. In another configuration, the first and second members may be,

is a superelastic material and can elastically deform until the material strains about 10%, so it is possible for the valve to deform towards a compact shape, still allowing elastic deployment to a final shape after placement.

The prosthetic valve made by the method of the present invention may be stentless or may comprise a stent attached to a leaflet assembly. Stentless valves or leaflet assemblies can also be used as valved, grafted or grafted valves; this means that its layer of support elements can be attached to the vessel wall or artery wall and act as grafts to (partially) replace or reinforce the delicate or aneurysmal vessels. In such embodiments, the outer portion of the leaflet assembly (the support member layer) may be further treated to reduce permeability, such as by providing a coating or another layer of material. Prosthetic valves with stents offer some other advantages, such as being implantable by minimally invasive techniques using a catheter system. In one embodiment, the method therefore further comprises: the leaflet assembly is attached to a stent.

In another embodiment, the prosthetic valve comprises two leaflets as defined above, wherein the second leaflet acts as the closing surface of the first leaflet and vice versa. The prosthetic valve may also comprise three leaflets, in which case each leaflet acts as a closing surface for the other two leaflets.

The prosthetic valves described herein may be used to replace mammalian valves (e.g., human venous valves or heart valves), by surgical treatment, by conventional procedures, or by minimally invasive and percutaneous techniques, depending on the type of stent optionally used in the prosthetic valve.

In addition to the embodiments described above, the prosthetic valve and the method of making such a valve will now be further explained using some schematic drawings, which are not necessarily to scale and which may not show all features or components for the sake of clarity. Like reference numbers in different figures refer to like features.

FIG. 1 includes sub-figures 1A-1I, which schematically illustrate various steps of one embodiment of a method of forming a prosthetic valve. In fig. 1A loom 100 is depicted having 4 warp beams (or pirn picks) 101, 102, 103 and 104. Warp yarn 10 is connected between the top two warp beams 101 and 103 and the bottom two warp beams 102 and 104. In this way, a woven structure having two plies can be formed in a weaving process using a weaving machine arrangement. For reasons of clarity, not shown are the usual other parts of the loom, such as heald frames (or harness), in which the heddles are spaced from a predetermined pattern of warp yarns in one layer (or in both layers) to form open spaces (or warp openings) capable of passing through a filling yarn (also called weft) (shuttle or pick carrying filling yarn); and optionally a bar (bat) (or reed) for pushing the stuffer yarn toward the fell. The warp yarns may be attached to a warp beam (typically used in discontinuous processes) or may be continuously supplied using warp beams 101 and 102 as guide members, and in this case 103 and 104 represent a single fabric beam for receiving the finished double-layer fabric. The stuffer yarns 11 shown in figure 1A are woven in the upper layer 3 of the textile structure 1 by interweaving the stuffer yarns with the warp yarns above (e.g., forming a plain weave) and are carried back towards the fold line 12 on the border 5 of the layer 3, where they are woven in the lower layer 2 until they reach the border 4 of the lower layer and are carried back towards the fold line 12. Note that for the sake of clarity, the fold lines are made to appear larger in the figures than in practice. In this way, edges 5 and 4 form selvedges. The weaving process continues until the woven structure has the desired dimensions. The result is a double woven textile structure comprising a first distinct layer 2 having a selvedge 4 and a second distinct layer 3 having a selvedge 5. Layer 2 is connected to layer 3 along fold line 12 by passing the stuffer yarns from one layer to the other. These layers 2 and 3 will form the support elements and leaflets, respectively, of the final valve, and the fold line 12 may form part of the connection between the support elements and the leaflets. An alternative embodiment further comprises: the layers 2 and 3 are interwoven by crossing the yarns between the layers, rather than at the fold lines, to create additional connections and form, for example, more segments (sections) in the layers.

After weaving the textile structure 1 on the loom 100, the textile structure 1 is released from the loom as shown in fig. 1B. It is now clear that the textile structure is woven as a double layer weave (or double width) cloth having distinct layers 2 and 3, each having selvedges 4 and 5, respectively. The warp threads 10 extend at the non-woven edge over a small length beyond the actual textile structure. These edges may optionally be stabilized at this stage or later.

In the next step, as shown in fig. 1C, stitches 22 are further added (next to fold line 12) to join layers 3 and 2. By adding two sutures 22 to this structure, the layer 3 is divided into three separate segments, which correspond to the individual leaflets of the valve.

In the next step, as shown in fig. 1D and 1E, the two non-woven edges are brought together (i.e., the proximal and distal ends of the structure are arranged on top of each other) so that the woven structure forms a tubular structure. As can be seen in fig. 1D and 1E, the leaflets of layer 3 are located inside the structure, while the support elements of layer 2 are located outside the structure. At the closure 9 of the loop, the warp yarns 10 of the two edges of the textile structure meet. The ring closure 9 is then machined to ensure that it can withstand the mechanical forces exerted on the prosthetic valve when in use. First, the loose warp ends may be cut and then, as shown in fig. 1E, the closure 9 is folded towards the surface of the layer 2, after which the closure 9 is reinforced with stitches 30. Alternatively, the folded end is first rolled and then folded towards the layer 2. In this way, any loose warp ends are no longer freely exposed, but the disadvantages are: the rolled closure 9 is slightly thicker than the non-rolled closure. Further alternatives are: the edges are stabilized and then stitched to layer 2.

In another step, as shown in fig. 1F, additional sutures 31 are added, for example along U-shaped lines, which further join segments of layer 3 and corresponding segments in layer 2 to better define leaflets or to make a 3D-like shape. In fig. 1F, a section of a tubular structure is shown, which shows a combination of support elements and leaflets. It can be seen that the free edge of the leaflet is formed by selvedge 5. Starting from the free edge, the resulting connection comprises the suture 22 and the suture 31. The sutures 22 and 31 may also be continuous, i.e., the suture 22 may not extend the entire height of the valve, but may be deflected and continue to form a U-shaped curve of the suture, designated 31. In this manner, the leaflets and support member cooperate to form a pocket. By occupying a position adjacent to the support element, the leaflets can open the final valve; by occupying a position extending away from the support member, the leaflets can close the final valve.

Referring now to fig. 1G, to even better shape the leaflets and pockets, a mold 37 can be used. Prior to suturing the connecting thread 31, the mold 37 may transform the shape of the leaflets, optionally by pulling the leaflets upwards at the rim 5. In this way, additional length is created along the leaflets between the center and nadir of the valve. Another way to create this extra length is to: by using more warp yarns in layer 3 than in layer 2, a larger layer 3 (segments in) than in layer 2 has been woven. The steps illustrated in fig. 1F and 1G may also be performed during or after attachment to the stent.

Referring now to fig. 1H and 1I, the resulting textile structure or leaflet assembly is attached to a circular wire stent 40 to make a valve 400. The leaflet assembly is placed within the stent and may be sutured to the stent at its bottom using sutures 33 and to the support element 2 at the top using sutures 32. Such sutures 32 preferably continue to attach the leaflets and support elements to the tri-stent strut 41 (see fig. 1I), which also forms the final commissure. Also depicted in fig. 1H are the free edges 5 of the three leaflets. In this form, the valve 400 is closed by coaptation of the leaflets in the neutral position. If the free edge 5 is adjacent to the support element 2 (i.e. adjacent to the wall of the stent 40), the valve 400 will open. Some more details of the support structure and its pillars 41 are depicted in fig. 1I. After circumferentially joining the fabric, a knot 36 is created at the seam 32 as a point of attachment for the seam. In an alternative approach, the suture 33 may be created at this stage; the temporary connection 35 can then be used to hold the structure in place during stitching to the post 41, after which it can be removed. Fig. 1I shows an alternative embodiment in which the leaflet assembly protrudes beyond the bottom of the stent and this portion can be folded over and attached to the stent in a further step. Its advantages can be: following implantation, more readily conforms to the vessel or artery.

In an alternative embodiment, rather than using stitches 22 early in the forming process (as shown in fig. 1C), the double woven textile structure itself (as shown in fig. 1B) is tightly wrapped around a stent 40 (at this stage, the stent is covered by a protective plastic sheet) or another forming member (such as a short bar) and the four layers of the enclosure 9 are sewn together. Thereafter, the stent is carefully removed and the tubular structure is placed within the stent. Then, stitches (sutures) corresponding to the stitches 31, 32, and 33 are provided to form the leaflet cusps and to fix the textile structure to the stent.

Fig. 2, which consists of sub-figures 2A, 2B and 2C, schematically shows various views of a textile structure for making a prosthetic valve according to the present invention. In the embodiment of fig. 2A, a cross-section parallel to the stuffer yarns of the textile construction 1 in the S-direction as shown in fig. 1A is given. It can be seen that the packing yarns 11 are interwoven with the warp yarns 10 in layers 2 and 3, thereby forming a plain weave. By using the double weaving process described in figure 1, layers 2 and 3 have longitudinal (i.e., parallel to the warp yarns) selvedges 4 and 5, respectively. The packing yarn at the fold line 12 is transferred from layer 2 to layer 3 and vice versa, forming part of the final connection between the leaflet and the support element. In fig. 2B, a side view of such a textile structure in the V-direction as shown in fig. 2A is given. In this view, selvedges 4 and 5 are only schematically depicted.

In an alternative embodiment, as depicted in fig. 2C and representing a similar viewing angle as in fig. 2B, the stuffer yarns are interwoven with the warp yarns such that crossovers 220 are formed in the textile structure. The textile structure 1 now comprises a total of 6 segments in both layers, namely segments 2 ', 2 "and 2'" in the top layer and segments 3 ', 3 "and 3'" in the bottom layer. At the left cross line 220, the four segments 2 ', 2 ", 3' and 3" conform to a line which will correspond to (a part of) the commissures of the final valve. For this purpose, the warp yarns are transferred from section 2 'to section 3 "and the warp yarns are transferred from section 3' to section 2", which is controlled by the movement pattern of the heddles and warp yarns during weaving. In this way, not only is a common (muscular) configuration obtained, in which each segment corresponds to a support element or a leaflet, but as a direct result of the weaving process, a leaflet-support element connection is formed, with a strength similar to that of the fabric itself. This also means that: fewer sutures need to be added (or even no sutures need to be added) to form the final joint, including attachment to the stent. The corresponding weaving process occurs at the right hand crosshatch 220. By connecting the ends of the structure obtained as depicted in fig. 2C, a tubular three-leaflet structure is obtained.

Fig. 3, which is composed of sub-figures 3A, 3B and 3C, schematically shows the geometry applied according to the invention, and the geometry according to the prior art. In each schematic drawing, a cross-section is depicted through the centre line of a valve having two opposed leaflets 3 and 3 ', which are in a closed but neutral position when unloaded, and which are connected to their respective support elements 2 and 2 ' at respective lowest points 120 and 120 ' in the depicted cross-section. Note that for a valve with three leaflets, a plane through the centerline of one leaflet may be at an angle of 60 degrees to the central plane of the opposing leaflet.

Fig. 3A shows the geometry applied to the two leaflets when there is no pulsating load, such as when manufactured according to the method of Heim (see references Materials and Manufacturing Processes mentioned above). In the center of the valve, there is a large gap G in neutral position when there is no load. Under pulsatile load, the gap will close and open further by expanding the leaflet material (about 15%, partly due to the elongation of the polyester yarns, partly due to the rearrangement of the yarns in the textile), thereby mimicking the dynamics of a natural valve. In the absence of pulsating load, the leaflet had a radius of curvature of about 50 mm.

Fig. 3B shows a cross-section of a leaflet assembly in a prosthetic valve according to the present invention. In neutral position with no arterial load, the opposing leaflets 3 and 3' have an imposed geometry that causes them to abut each other along the free edge length, and thus also at the center of the valve, forming a commissure 700 of commissure height H across this cross-section. In this embodiment, the junction height H is 6mm in the center and extends at least 0.1mm across the free edge length of each leaflet (the base of which is indicated by reference numeral 300), wherein it may also be even larger towards the junction depending on the length of the junction. The geometry of each leaflet also includes a convex surface extending between the top of the closure surface H and the respective connection to the support element, with nadirs 120 and 120' shown in the cross-section of the valve in fig. 3B. Each convex surface is convex away from the respective support element 2 and 2'.

Shown in fig. 3C: by the slight hydrostatic pressure (which results from filling the bag with water 600 as shown), the applied geometry and engagement height (including the formation of a closed "band" with self-contained edge length) can be more easily checked and its dimensions estimated. It should be noted that due to the extra length of the free edge (more woven length than is actually needed to span the distance between the support elements and fasten), there may be wrinkles or small openings (channels) in the closing surface at some point when the valve is closed by filling it with water. But such an opening is not permanent and will in actual use be closed by pulsation. The curvature of the leaflet can also be characterized by a bending height h, defined as the maximum orthogonal distance between a straight line connecting the nadir and the free edge of the center of the valve and the centerline.

Fig. 4, which is composed of sub-fig. 4A and 4B, schematically shows a continuous structure produced according to another embodiment consistent with the method described in connection with fig. 2C. In this embodiment, the textile structure 1 is woven with two types of stuffer yarns (one for each layer) such that the top layer 2 and the bottom layer 3 have selvedges on both sides (4, 4 ', 5, and 5'). In the width direction, layer 2 is larger than layer 3, which is achieved by using more warp yarns; note that for both layers, only the warp yarns 10 are depicted at the edges. In the resulting leaflet assembly, the support member will therefore be longer and extend away from the leaflet; and thus may be used, for example, to fold around a stent. Selvedges 5 or 5' may be formed at the free edges of the leaflets in the resulting valve. In an alternative embodiment, a layer of extended support elements may be used to attach the leaflet assembly to the vessel wall or artery wall, acting as a graft to (partially) replace or reinforce a delicate or aneurysmal vessel. Such leaflet assemblies (again without a stent) may thus function as valves and grafts, and may be referred to as valved-grafts or grafted-valves. In such embodiments, the outer portion of the leaflet assembly (the support member layer) may be further treated to reduce permeability, such as by providing a coating or another layer of material.

The bottom layer is expanded with additional filling yarns to increase the size of (the free edges of) the leaflets. When the desired extra length of the leaflet is reached, the layer 3 is pulled back with the retaining bar 105 so that the fill line of the top layer coincides with the fill line of the bottom layer, as shown in fig. 4A. Then crossing the bottom warp yarn and the warp yarn of the corresponding portion of the top layer to form a cross 220; this is also shown in fig. 4B. These cross-wires provide a commissure extending parallel to the longitudinal axis in the final valve formed by the structure 1, at least over the length formed by the cross-wires 220, starting from the free edge (corresponding to the method outlined in fig. 1). After weaving, the product may be cut to a desired length and then joined to form a tubular structure, and optionally to a stent.

Alternatively, the leaflets can be made larger than the support member. In a further alternative method, a fold line is formed at one edge by crossing the stuffer yarns with another set of warp yarns.

Figure 5 shows schematically how the selvedge is woven, even at the edges perpendicular to the warp direction WA. In this case, connected to the beam 101 is a stay (stay) comprising a plurality of curved portions 62. The warp yarns 10 each form a loop and each of these loops is connected to the beam with a bend of a stay, which thus extends between the beam 101 and the loop. The packing yarn 11 is interwoven with the warp yarn 10 in a packing direction WE. In this particular embodiment, a cord 60 is used to secure the loop to the curved portion 62. To this end, the cord 60 extends along the edge 13 through each loop of warp yarns and is connected to the warp beam with the stay shown above. In this case the cord 60 is a section of the warp yarn and continues further as a filling yarn 11, so that no loose end is adjacent to the border 13.

By using this method, the warp yarns at the edge 13 form a loop and are thus continuous at the edge, which thus forms a selvedge. In this case, the selvedge extends in a filling direction WE perpendicular to the warp direction WA. The resulting flat fabric thus has selvedges at least at its three edges. This method of forming selvedges in warp threads can also suitably be used to form non-flat structures but e.g. tubular textile structures, where the edge or edges correspond to the free edges of the leaflets of the final valve. Examples of such tubular textile structures are schematically depicted in the following figures.

In another embodiment, the curved portion connects the warp beam directly to the warp loops. In order to prevent the free ends of the stuffer yarns, it is preferable to wind the stuffer yarns in a manner to wrap around one of the warp yarns (if the fabric is a flat fabric, the yarn near one side of the fabric is advantageous), and then weave using both ends of the stuffer yarns as separate stuffer yarns.

The inventors have found that the use of UHMWPE yarns as the packing yarns is particularly advantageous when producing woven fabrics having selvedges parallel to the packing yarns, because such yarns tend to be transversely aligned to fill the loops of the warp yarns when removing the dwells or knuckles. It can be inferred theoretically (without intending to be limited thereto): this unexpected finding with respect to yarns having very high strength and modulus is related to the combination of the low coefficient of friction of UHMWPE and the bending flexibility of UHMWPE yarns.

Fig. 6, which is comprised of sub-figures 6A-6F, schematically illustrates various steps in another embodiment, in which a tubular (looped) woven textile structure is used to make a leaflet assembly for a valve.

Fig. 6A (warp direction denoted "WA" and filling direction denoted "WE") shows a woven tubular textile structure 1, which consists of a tubular inner layer 2 (corresponding to the support element of the final valve described in fig. 6E) and an outer layer 3 with three segments (which would correspond to leaflets with extra length at the free edges). The outer and inner layers are connected along three lines 220. In this embodiment, the tubular inner layer 2 has a selvedge 4 and the layer 3 has a selvedge 5, which is a textile structure produced by a method such as that described in figure 5 using a specially designed warp beam. Alternatively, such structures are manufactured in a continuous weaving process, which is subsequently cut to the desired length and produce a stabilized edge. The leaflet segments in layer 3 are connected to the support elements in layer 2 by cross-hairs 220 (corresponding to cross-hairs 220 depicted in fig. 2C, but in this case the filler yarns cross, whereas in fig. 2C the warp yarns cross).

Fig. 6B shows a top view (or cross-sectional view) (in the warp direction) of the textile structure of fig. 6A. Fig. 6C gives the same view, but with the textile structure from its original flattened form now configured such that layer 2 forms an annular tube. The leaflet segments of layer 3 extend over the surface of such a tube and meet at a line of intersection 220. In the next process step, the textile structure of fig. 6C is turned inside out, which results in a structure as depicted in fig. 6D. At this stage, the textile structure is processed so that the support elements 2 are external and the leaflets 3 are internal, forming a leaflet assembly or valve 400 (in a closed valve configuration) shown in isometric view in fig. 6E.

An alternative embodiment of a woven structure using a method similar to that described above is schematically depicted in fig. 6F, in which layer 2 (different from the structure shown in fig. 6A) extends a longer distance than layer 3. In such an embodiment, the edges 5 of the leaflet segments in layer 3 form a selvedge (e.g., using a looped warp beam and using the method depicted in fig. 5), and the edges of layer 2 are woven into a regular border where the warp yarns are discontinuous (e.g., discontinuous as they are cut to release the structure from the loom). For simplicity, only some ends of warp yarn 10 are depicted, similar to fig. 6A. This textile structure can be formed into a valve in the same way as the structure of fig. 6A (i.e., by inversion). The advantages of the resulting leaflet assembly are: the support member is longer, extending away from the actual leaflets, and thus can be used, for example, to attach to the exterior of a stent used in the manufacture of a prosthetic valve or to attach the leaflet assembly to an artery as a valved graft. Similarly, layer 2 may extend at the opposite end of the structure, or layer 3 may be made larger.

The invention will be further illustrated by the following exemplary experiments.

Example 1

This example describes the manufacture of a prosthetic valve according to the invention and experiments in which such a valve was tested in vitro and used as a lung valve prosthesis by implantation in sheep. In this embodiment, each valve is manufactured using the method described below, which is substantially identical to the method described in connection with fig. 1 and 3B.

From Dyneema

The woven fabric shown in figure 1B was made with TG 10dtex UHMWPE multifilament yarns (available from DSM, the netherlands) at a density of 458 ends per inch and 223 fill yarns per inch. The folded double layer structure had a length of 90mm, a width of 21.5mm and a layer thickness of 0.00314 inches (80 μm) and was woven as a 2 x2 twill weave with longitudinal selvedges. The cylindrical holder used has the design shown in fig. 1I and is made of electromagnetic polished stainless steel 304. Its outer diameter is 25mm, its inner diameter is 23mm and its height is 17 mm. For sutures, two sutures were used: maxwoven PE 3-0 blue suture (suture blue) with tapered needle (available from BIOMET MERCK LTD as MPC 900252), referred to hereinafter as suture A; and Maxwoven PE 4-0 blue suture with tapered needles (available from the same supplier as MPC 900244), referred to hereinafter as suture B. Both sutures contain UHMWPE yarns.

A lung valve was manufactured as follows. To produce a coaptation height of 6mm over the leaflet free edge length, a large number of free edge lengths are produced. The free edge length is made too large by the following steps:

1. the leaflet free edge length in the woven textile structure will be inherently equal to the support element length, with both layers having the same length. The distance between the edges of the support elements forming the cylinder and the middle of the valve is the radius R of the valve, the total length required for 3 leaflets to bridge this distance is 6R, while the length of the support elements is 2 rr. This creates an inherent extra length factor of 2 pi R/6R-1.05 for the leaflet.

2. The double woven fabric was first wrapped around (i.e., wrapped outside) the 25mm stent and then the ends perpendicular to the free edges of the leaflets were sewn together. Subsequently, the cylindrical textile structure was placed inside a stent with an inner diameter of 23mm and fixed to the stent with UHMWPE sutures. This creates an extra length factor of 25/23 ═ 1.09.

3. In this example, the final prosthetic heart valve size for implantation is 23mm, since this 25mm diameter stent is radially compressed to 23 mm. In this way, the inner diameter of the stent to which the support elements and leaflets are secured is reduced from 23mm to 21 mm. This creates an extra length factor of 23/21 ═ 1.10.

The total extra length factor of the leaflet free edge created in this way is pi x25/3x 21-1.25. The extra length thus created is about 25%.

As indicated above, the woven fabric was tightly wrapped around the stent (originally used as a mold), and then four layers at the closure (corresponding to 9 in fig. 1D) were sewn together using suture a, starting from the outflow side of the fabric/stent combination, by the following method: knots 36 are created leaving about 2cm loose ends and long ends for creating sutures toward the entry side of the fabric/valve combination. The stent/mold is carefully removed and the tubular textile structure is then placed within the stent. The direction of the warp threads of the leaflets and support elements is perpendicular to the longitudinal central axis of the stent and engages the stent struts, so that the filler yarns are parallel to the central axis and engage the stent struts. The suture a is then guided through the rim and stent post hole from the entry side toward the exit side (as shown in fig. 1I), securing the stent post 41 to the support element and leaflet in a length of about 9 mm. At the top (outflow side) of the post, the edge of the support element is fixed to the stent using a suture a in a continuous manner through a locked bite (padded bit) occupying the curved end of the stent (the well-known "Blalock method" using festooning suture). At the loose end of knot 36, the end of suture a is tied to its starting point. Temporarily fixing the textile structure to the remaining splice bracket post 41 at 120 degrees, thereby dividing it into three sections having approximately the same free edge length to hold the structure in place during the next step; the temporary fixation can then be removed.

The joining of the textile structures and the creation of the actual leaflet assembly within the stent is accomplished by the following procedure using the second suture B: the two remaining stent posts 41 are sutured to approximately 9mm in length, and the leaflet layer is sutured to the support element layer and stent to create the valve cusp. The free edges of all 3 individual leaflets are pulled up 3mm in the middle of the free edges before sewing, at the expense of the length of the inflow side support element, creating an arcuate weave between the commissure posts that rises throughout the plane of the outflow side of the stent. This, together with the extra length mentioned above, produces a coaptation height of about 6mm in the center of the heart valve, and most likely even higher towards the commissures: is about 9 mm. A mold (negative form taken from a human aortic valve) was used to further shape and size the convex portion (belly) of the leaflet shown in fig. 1G. The leaflet assembly is temporarily sutured (35) in the middle between the posts on the inflow side to maintain this configuration during the next step. From this point, stitching is started according to fig. 1I. At the top of the post, the leaflets and support elements are doubly fixed with two encircling occlusions. The leaflet sheet is pulled back a little bit over the top of the stent and secured by sutures. The course of the (U-shaped) leaflet sutures is also controlled by the shape of the stent and the mold. The suture ends are tied to the remaining loose ends at the knot at the beginning of suture B. The resulting leaflet had a convex surface at its centerline with a radius of curvature of about 12mm in the absence of pulsatile loading. This is expected to represent a distance h along the centerline height h of about 5mm as shown in fig. 3C. The textile structure extends a few millimeters from the stent at the inflow location (also shown in fig. 1I), which can be used to attach the valve to the vessel or artery wall after implantation. The leaflet assembly is further attached to the lower portion of the stent with sutures and the temporary sutures 35 are removed.

After the leaflet assembly is thus fixed, the stent 40 of the valve is compressed from a diameter of 25mm to a diameter of 23mm, and then sterilized by sterilization using ethylene oxide.

Valves made as described above were tested in vitro and in vivo for performance. Mechanical and functional testing of the prosthetic heart valve is performed in a simplified simulated cycle. BVS 5000 circulatory assistance (Abiomed, Danvers, MA, usa) is contained in a closed loop circuit with a reservoir and return line. The heart Pump Balloon was driven by an Intra oral Balloon Pump (Maquet, Rastatt, germany) with a frequency of 80 beats/minute and an output of 3600 cc/minute, while the afterload on the outflow side of the heart Pump was set to 80mmHg using the water column. In an initial experiment, the standard valve of the outflow-side heart pump was replaced by a valve constructed with three separate leaflets made of 55dtex UHMWPE yarn mounted in transparent plastic tubing to investigate its opening and closing properties. The guide valve was competent and maintained without degradation of the woven leaflets for >4 weeks (3571200 cycles). Based on this experience, the valves constructed as above (based on leaflets made of woven fabric of 10dtex UHMWPE yarns) were tested under equivalent physiological load conditions of human circulation, accumulating for more than 120 days (13824000 cycles). The valve opens sufficiently for an optimally effective orifice, where the oscillating leaflets parallel to the flow have a known vertical position, and close while visually no closure defects (other than a tiny central orifice of about 0.5 mm) are observed along the coaptation line of the free edges of the converging leaflets. Visual inspection after testing showed intact valve geometry; the leaflets do not show free edge wear or any other damage or defect. All sutures and knots as described above are intact.

Pulmonary prosthetic valves were also implanted into the beating heart of a model adult sheep (broken "swift", body mass 55-70 kg) while using an extracorporeal circulation machine. Access to the pulmonary artery was achieved by left thoracotomy, 3-4i.c.s. The pulmonary artery is cut longitudinally and then the native leaflets are excised. Using 3 roots of 5-0

The positioning sutures tautly engage the native posts. Using 5-0

The valve was sutured to the pulmonary artery at the level of the supraannular (supranuclear) valve (planar top of the native commissures). The pulmonary artery is occluded in a linear fashion.

Echocardiography showed normal leaflet function with no valvular or paravalvular regurgitation, except for some occasional minimal regurgitation in the center of the valve. The wound was closed and the sheep were taken back to the barn for recovery.

Sheep remained stable without any adverse clinical symptoms until the 6 month observation period. After this period, leaflet function was again assessed. Echocardiography showed adequate leaflet function with little to moderate valvular regurgitation but no paravalvular regurgitation and no change in effective orifice from the date of implantation. Thereafter, the valve was removed from the sheep for examination. The leaflets and support elements overgrow with the tissue, but this shows a very thin layer of fibroblasts and endothelial cells, without histological and radiological signs of tissue calcification, and with a maximum thickness (including the leaflets) of 250 μm at the free edges, and the amount of streamlined repair tissue increases towards the lowest point. The structure of the valve appeared unchanged, all the sutures were in place without breaking and the free edges of the leaflets appeared intact as originally manufactured. Signs of wear or other anomalies are not detected. To the best of the inventors' knowledge, there was no other study using a prosthetic valve with leaflets made of fabric woven from synthetic fibers with the characteristics that the animal with this implanted valve survived for 6 months without complications.

Example 2

An artificial aortic valve to be implanted in the systemic circulation was made similar to example 1 but with some variability. The support element was prepared as follows: three half-moon shaped fabrics (facing the fossa veronii in the aorta of a human or animal) were removed to allow blood supply to flow into the coronary ostia. The remaining edge of the support element is fixed to the leaflet according to the corresponding suture of the U-shaped cusp suture (facing the antrum of the fossa flaccid). The joining of the textile structures and the creation of the actual leaflet assembly within the stent is accomplished by the following procedure using a second suture: suture to the stent post 41 at a length of about 9mm and suture the leaflet layer to the support element layer and stent to create the valve cusp.

The valve is then constructed in a manner similar to that described above with respect to the pulmonary valve. When complete, make use of MaxBraid^TM3-0UHMWPE (available from Teleflex, Li)merick, ireland), an additional sewn cuff (sewing cuff) of braided UHMWPE yarns is sewn in a Blalock stitch configuration in a flip-over (everted) manner.

The valves were implanted on the arrested heart in an adult sheep model (break "swifter", body mass 65kg) with the support of extracorporeal circulation. Access to the aortic root was achieved by left thoracotomy, 3-4i.c.s. The pulmonary artery is cut and pulled aside to allow transection of the aorta. Using continuous suture

5-0 conventional implantation is performed in the event of cardiac arrest. The aorta is closed with a pericardial patch, after which the heart is defibrillated. The heart-lung machine was turned off. Echocardiography showed normal leaflet function, with no valvular or paravalvular regurgitation.

Example 3

A chemically prepared flat sheet of porcine intestinal submucosa (

Roswell, usa) constructed valved catheters or valved grafts. In a series of sheep and lambs, valves of 25mm and 18mm in diameter, respectively, were implanted as insertion grafts between the outflow tract of the right ventricle and the distal main pulmonary artery. The surgical procedure was the same as described in example 1 and was performed using an extracorporeal circulation support. The pulmonary artery is transected above the pulmonary valve, which is then removed. For a catheter/valve of 25mm diameter, a trapezoidal sheet is prepared having a width (a) of about 12cm and a width (B) of about 14 cm and having two sides (C and D) of length greater than 10 cm. For flat sheets, the free-hypotenuses C and D are combined with the decorations 4-0 by turning over

The sutures are sewn together to construct the conical tube. The extra material is cut off and the tube is then folded and inverted so that the tubular member with the larger circumferential edge B is inside the tube with the circumferential edge a (outflow side) and leaving a folded edge on the inflow side. Will form small leavesThe annular border B of the free edge is divided into three portions of equal length, which are then fixed to the outer tube at 120 ° each by means of a stitch (Prolene 4-0) with cotton wool. Thus, 3 commissures of 3-4mm in the longitudinal direction of the valve are created, and in the absence of load, the free edges of which have an extra length of 3 individual leaflet commissures, the commissure height being at least 7 mm. At the outflow side of a, a cuff remains, which is used to connect the valve during implantation into the transected pulmonary artery. The inflow side of the tube with the folded edge is connected to the pulmonary artery stump. After implantation, echocardiography showed normal leaflet function, with no valvular insufficiency except for some occasional minimal regurgitation in the center of the valve.

Any of the embodiments, aspects and preferred features or ranges disclosed in this application with respect to a method of manufacturing a prosthetic valve or a valve obtained using said method may be combined in any combination, unless otherwise stated or would be technically unfeasible to a person skilled in the art. The invention is further summarized in the following set of embodiments.

A prosthetic valve (400) comprising a leaflet assembly having at least one leaflet (3) connected to a support element (2), the leaflet having a free edge (5) movable between a first position and a second position, wherein in the first position the free edge flexes away from a closure surface (700) to allow bodily fluids to flow through the valve; in the second position, the free edge abuts the closure surface to close the valve, and wherein the leaflets are capable of forming a coaptation height along the length of the free edge of greater than 0.1mm in the absence of a pulsatile load on the valve.

The prosthetic valve according to the previous embodiment, wherein the coaptation height is 1-15mm, preferably 3-10mm, more preferably 5-7 mm.

The prosthetic valve according to the previous embodiment, wherein the geometry of the leaflet comprises a convex surface having a radius of curvature at the leaflet centerline of 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, or 20 mm.

The prosthetic valve according to the previous embodiment, wherein the radius of curvature is 1-20mm, preferably about 12 mm.

A prosthetic valve according to any of the preceding embodiments, wherein the leaflet geometry comprises a convex surface having a curved height of greater than 1mm, preferably greater than 2mm, 3mm or 4mm and up to 15mm, 14mm, 13mm, 12mm, 11mm or 10mm, most preferably about 5mm, the curved height being the maximum orthogonal distance between the centre line and a straight line connecting the nadir and the free edge of the valve centre.

A prosthetic valve according to any of the preceding embodiments, wherein the free edges of the leaflets have an extra length relative to the theoretical length required to close the valve, preferably the extra length is at least 7%, preferably 10-40%, or 15-30%.

A prosthetic valve according to any of the preceding embodiments, wherein the leaflets are connected to the support element along commissures extending from the free edges parallel to the longitudinal axis of the valve, preferably the commissures have a length of at least 1mm and at most 9mm, preferably 1-6 mm.

A prosthetic valve according to any of the preceding embodiments, wherein the leaflets comprise an elastic sheet having an elongation at break of 10% or less, preferably less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or even 1%.

A prosthetic valve according to any of the preceding embodiments, wherein the leaflet comprises a woven structure comprising one or more elastic yarns having an elongation at break of 10% or less, preferably less than 9%, 8%, 7%, 6% or 5%, more preferably 1-5%.

The prosthetic valve according to the previous embodiment, wherein the woven structure is a woven fabric made of one or more elastic yarns, and preferably the woven fabric comprises a plain, twill or basket weave pattern.

The prosthetic valve according to the previous embodiment, wherein the textile structure is a piece of woven fabric, preferably a piece of woven fabric comprising a plurality of laminations.

The prosthetic valve according to the previous embodiment, wherein the free edge of the leaflet is a selvedge of the woven fabric.

The prosthetic valve according to the previous embodiment, wherein the textile structure is a multi-layer woven fabric comprising a stack of layers, the layers being interconnected at desired locations, preferably by intersecting warp or fill yarns, to define the leaflets and the support elements.

The prosthetic valve according to the previous embodiment, wherein the woven fabric is a double-layer fabric comprising two selvedges at the open side and continuous folding lines at the opposite closed side.

A prosthetic valve according to the previous embodiments, wherein the woven textile structure is a seamless tubular fabric, optionally a multi-channel or multi-layer tubular fabric.

A prosthetic valve according to the previous embodiment, made by the method of: the textile structure is continuously woven, the resulting structure is subsequently cut to a desired length, and the cut edges are optionally stabilized.

The prosthetic valve according to the previous embodiment, wherein the linear density of the elastic yarns is less than 120dtex, preferably the linear density of the elastic yarns is less than 60dtex, preferably between 5 and 30dtex, more preferably between 7 and 15 dtex.

The prosthetic valve according to the previous embodiment, wherein the thickness of one layer of the textile structure (preferably woven fabric) is 20-200 μm, preferably 40-150 μm or 50-100 μm.

The prosthetic valve according to the previous embodiment, wherein the textile structure comprises polymer filaments, preferably UHMWPE filaments, more preferably the textile structure comprises at least 80 mass% UHMWPE filaments having a tenacity of at least 20cN/dtex, more preferably the warp and filling yarns essentially consist of UHMWPE filaments.

The prosthetic valve according to any of the preceding embodiments, further comprising a stent (40) connected to the leaflet assembly.

The prosthetic valve according to the previous embodiment, wherein the stent is connected by sutures, preferably by sutures made with sutures having similar strength to the yarns in the leaflet assembly, more preferably by sutures made with or from the same type of yarns.

A prosthetic valve according to any of the preceding embodiments, wherein the valve comprises two leaflets and the second leaflet acts as a closing surface for the first leaflet and vice versa.

A prosthetic valve according to the previous embodiment, wherein the valve comprises three leaflets, each leaflet serving as a closing surface for two other leaflets.

The prosthetic valve according to any of the preceding embodiments, which is an implantable prosthetic heart valve.

A leaflet assembly for use in the prosthetic valve of any of the preceding embodiments.

A method of manufacturing a prosthetic valve (400) comprising at least one leaflet (3) connected to a support element (2), the leaflet having a free edge (5) movable between a first position and a second position, wherein in the first position the free edge is curved away from a closure surface (700) to allow bodily fluid to flow through the valve; in the second position, the free edge abuts the closure surface to close the valve, the method comprising:

-providing a sheet of material,

-forming a leaflet assembly from the sheet, the leaflet assembly comprising at least one leaflet and a support member, and

-thereby forming a valve,

wherein forming the leaflet assembly comprises: shaping the leaflets to impart a geometry wherein the leaflets are capable of forming a coaptation height along the length of the free edge of greater than 0.1mm in the absence of a pulsatile load on the valve.

The method according to the preceding embodiment, wherein the engagement height is at least 2mm, 3mm, 4mm or 5mm and at most 15mm, 13mm, 11mm, 10mm, 9mm, 8mm or 7 mm.

The method according to the previous embodiment, wherein the engagement height is 1-15mm, preferably 3-10mm, more preferably 5-7 mm.

The method according to any one of the preceding embodiments, wherein the geometry comprises a convex surface having a radius of curvature at a leaflet centerline of 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, or 20 mm.

The method according to the previous embodiment, wherein the radius of curvature is between 1 and 20mm, preferably about 12 mm.

The method according to any one of the preceding embodiments, wherein the geometry comprises a convex surface having a height of curvature of more than 1mm, preferably more than 2mm, 3mm or 4mm and at most 15mm, 14mm, 13mm, 12mm, 11mm or 10mm, most preferably about 5 mm.

The method according to any of the preceding embodiments, wherein the leaflets are formed such that the free edges of the leaflets have an extra length relative to the theoretical length required to close the valve, preferably the extra length is at least 7%, preferably 10-40%, or 15-30%.

The method according to the previous embodiment, wherein said extra length is generated by one or more method steps selected from the group of: preforming the sheet into a particular shape, for example by forming a trapezoidal-like sheet or a tapered or conical tubular material, reducing the outer perimeter of the valve, and altering the leaflet surfaces, then securing the leaflets in the valve.

The method according to any of the preceding embodiments, wherein the leaflets are connected to the support element along commissures extending parallel to the longitudinal axis of the valve from the free edges, preferably the commissures have a length of at least 1mm and at most 9mm, preferably 1-6 mm.

The method according to any one of the preceding embodiments, wherein the sheet is an elastic material having an elongation at break of 10% or less, preferably less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or even 1%.

The method according to any one of the preceding embodiments, wherein the sheet is a textile structure comprising one or more elastic yarns having an elongation at break of 10% or less, preferably less than 9%, 8%, 7%, 6% or 5%, more preferably 1-5%.

The method according to the previous embodiment, wherein said textile structure is a structure woven from one or more elastic yarns, and preferably said woven fabric comprises a plain, twill or basket weave pattern.

The method according to the previous embodiment, characterized in that: wherein the textile structure is a woven structure, preferably a woven structure comprising a plurality of stacked layers.

The method according to the previous embodiment, wherein the free edge of the leaflet is woven into a selvedge.

The method according to the previous embodiment, wherein the textile structure is woven as a multi-layer structure comprising superposed layers, said layers being interconnected at desired locations, preferably by crossing warp or fill yarns, to define the leaflets and the support elements.

The method according to the previous embodiment, wherein the textile structure is manufactured by a double weaving process, resulting in a double layer fabric with two selvedges at the open side and a continuous folding line at the opposite closed side.

The method according to the previous embodiment, wherein the textile structure is manufactured by a double weaving process, resulting in a seamless tubular fabric, optionally a multi-channel or multi-layer tubular fabric.

The method according to the previous embodiment, comprising: the textile structure is continuously woven, the resulting structure is subsequently cut to a desired length, and the cut edges are optionally stabilized.

Method according to the previous embodiment, wherein the linear density of the elastic yarn is less than 120dtex, preferably the linear density of the elastic yarn is less than 60dtex, preferably between 5 and 30dtex, more preferably between 7 and 15 dtex.

The method according to the previous embodiment, wherein the thickness of one layer of said textile structure (preferably a woven fabric) is 20-200 μm, preferably 40-150 μm or 50-100 μm.

The method according to the previous embodiment, wherein the textile structure comprises polymer filaments, preferably UHMWPE filaments, more preferably the textile structure comprises at least 80 mass% UHMWPE filaments having a tenacity of at least 20cN/dtex, more preferably the warp and/or filling yarns consist of UHMWPE filaments.

The method according to any one of the preceding embodiments, further comprising: the leaflet assembly is attached to a support (40).

The method according to the previous embodiment, wherein the connection is made by applying a suture, preferably by using a suture having similar strength to the yarns in the leaflet assembly, more preferably by using the same type of yarns or sutures made thereof.

The method according to any of the preceding embodiments, wherein the valve comprises two leaflets and the second leaflet acts as a closing surface for the first leaflet and vice versa.

The method according to any of the preceding embodiments, wherein the valve comprises three leaflets, each leaflet serving as a closing surface for two other leaflets.

A method of manufacturing a leaflet assembly for use in a prosthetic valve as described in any of the preceding embodiments.

A leaflet assembly or prosthetic valve obtainable by the method according to any of the preceding embodiments.

Claims (26)

1. A prosthetic valve comprising a leaflet assembly having three leaflets connected to a support member, each leaflet serving as a closing surface for two other leaflets, the leaflets having free edges movable between a first position and a second position, wherein in the first position the free edges flex away from the closing surfaces to allow bodily fluids to flow through the valve; in the second position, the free edges abut the closure surface to close the valve, wherein the free edges of the leaflets have an extra length of at least 10% relative to a theoretical length required to close the valve, the theoretical length required to close the valve being a minimum length required to bridge the distance between the commissures via the center of the valve, and wherein the leaflets are capable of forming a coaptation height of 1-15mm along the length of the free edges in the absence of a pulsatile load on the valve.

2. The prosthetic valve of claim 1, wherein the coaptation height is 3-10 mm.

3. The prosthetic valve of claim 1, wherein the coaptation height is 5-7 mm.

4. The prosthetic valve of any of claims 1-3, wherein the free edges of the leaflets have an extra length of 15-30%.

5. The prosthetic valve according to any one of claims 1-3, wherein the leaflet is connected to the support element along a commissure extending from the free edge parallel to a longitudinal axis of the valve, and the commissure has a length of at least 1 mm.

6. The prosthetic valve of claim 5, wherein the commissure has a length of 1-6 mm.

7. The prosthetic valve of any of claims 1-3, wherein the leaflet comprises an elastic sheet having an elongation at break of 10% or less.

8. The prosthetic valve of claim 7, wherein the elastic sheet has an elongation at break of less than 5%.

9. The prosthetic valve of any of claims 1-3, wherein the leaflet comprises a textile structure comprising one or more elastic yarns having an elongation at break of 10% or less.

10. The prosthetic valve of claim 9, wherein the elastic yarn has an elongation at break of 1-5%.

11. The prosthetic valve of claim 9, wherein the textile structure is a woven fabric made of one or more elastic yarns.

12. The prosthetic valve of claim 9, wherein the textile structure is a piece of fabric.

13. The prosthetic valve of claim 11, wherein the free edge of the leaflet is a selvedge of a woven fabric.

14. The prosthetic valve according to any one of claims 9, wherein the textile structure is a multi-layer woven structure comprising laminations, the layers being interconnected at desired locations to define leaflets and support elements.

15. The prosthetic valve of claim 11, wherein the woven fabric is a double-layer fabric comprising two selvedges at an open side and continuous fold lines at an opposite closed side.

16. The prosthetic valve of claim 9, wherein the textile structure is a seamless tubular fabric.

17. The prosthetic valve of claim 9, wherein the elastic yarn has a linear density of less than 120 dtex.

18. The prosthetic valve of claim 17, wherein the linear density is between 5dtex and 30 dtex.

19. The prosthetic valve according to claim 9, wherein a thickness of one layer of the textile structure is 40-150 μ ι η.

20. The prosthetic valve of claim 9, wherein the woven structure comprises UHMWPE filaments.

21. The prosthetic valve according to claim 20, wherein the textile structure comprises at least 80 mass% UHMWPE filaments having a tenacity of at least 20 cN/dtex.

22. The prosthetic valve of any of claims 1-3, further comprising a stent coupled to the leaflet assembly.

23. The prosthetic valve according to any one of claims 1-3, which is an implantable prosthetic heart valve.

24. A leaflet assembly for use in the prosthetic valve of any one of claims 1-23.

25. A method of manufacturing a prosthetic valve, the valve comprising a leaflet assembly having three leaflets connected to a support member, each leaflet serving as a closing surface for two other leaflets, the leaflets having free edges movable between a first position and a second position, wherein in the first position the free edges are curved away from the closing surfaces to allow bodily fluids to flow through the valve; in the second position, the free edge abuts the closure surface to close the valve, the method comprising:

-providing a sheet of material,

-forming a leaflet assembly from the sheet, the leaflet assembly comprising at least three leaflets and a support member,

-thereby forming the valve,

wherein forming the leaflet assembly comprises: shaping the leaflets to impart a geometry wherein the free edges of the leaflets have at least 10% extra length relative to a theoretical length required to close the valve, the theoretical length required to close the valve being a minimum length required to bridge the distance between the commissures via the center of the valve, wherein the leaflets are capable of forming a coaptation height along the length of the free edges of greater than 1-15mm in the absence of a pulsatile load on the valve.

26. A leaflet assembly or prosthetic valve obtainable by the method of claim 25.

Images