Minimally invasive implantable valve prosthesis, and valve stent for connecting artificial valve leaflets

Abstract

The present invention relates to a valve stent for minimally invasive implantation in the human or animal body, at least comprising: a tubular stent framework, which can be mechanically compressed and unfolded and has an inlet opening and an outlet opening; and one or more receiving frames, integrated in the stent framework, for one or more valve leaflets, wherein the receiving frames for the valve leaflets are axially oriented in the lateral surface of the tubular stent framework, and the entire axial longitudinal extent H of the receiving frames is smaller than or equal to the section from the inlet opening to the outlet opening of the valve stent, wherein a region of more than or equal to 10% of the maximum longitudinal extent H of the receiving frame in the direction of the outlet opening is not arranged on the stent framework and is freely radially movable with respect to the stent framework. The present invention also relates to a valve prosthesis consisting of a valve stent according to the invention and one or more valve leaflets made of textile fabric.

Description

[0001] Minimally invasive implantable valve prosthesis and valve stent for connecting artificial valve leaflets

[0002] The present invention relates to a valve stent for minimally invasive implantation in the human or animal body, at least comprising a tubular, mechanically compressible and deployable stent framework with an inflow opening and an outflow opening and one or more receiving frames integrated in the stent framework for one or more valve leaflets, wherein the receiving frames for the valve leaflets are aligned axially in the lateral surface of the tubular stent framework and the total axial length H of the receiving frames is less than or equal to the distance from the inflow opening to the outflow opening of the valve stent, wherein a region of greater than or equal to 10% of the maximum length H of the receiving frame in the direction of the outflow opening is not arranged on the stent framework and is freely radially movable relative to the stent framework.Furthermore, the present invention relates to a valve prosthesis comprising a valve stent according to the invention and one or more valve leaflets made of textile fabric.

[0003] Medical advances, particularly in the last few decades, have made it possible to significantly extend the period of time available with a virtually unchanged quality of life. A significant contribution to improving quality of life has been made by artificial replacement materials and parts made from them, which are able to temporarily or permanently take over the functions of body parts that are not functioning at all or are only functioning inadequately. Examples include prostheses, which can be designed either as static supports, for example in the hip area, or as movable functional devices, for example in the form of knee prostheses or heart valves. The latter prostheses in particular are subject to high technical demands, as movable parts are exposed to a changing biomechanical load spectrum.This applies even more to heart valve prostheses, which must provide sufficient fatigue strength under mechanical stress for an estimated 200 million load cycles over a period of more than five years. Animal substitute materials in the form of porcine heart valves or porcine and bovine pericardial patches are typically used to assume these functions as valve leaflets. After decellularization, these materials consist essentially of collagen, which is naturally designed for the required long-term stability in terms of strength and elasticity. However, under in-vivo conditions in the human body, these inherently biocompatible materials tend to accumulate and deposit calcium, which inevitably contributes to the stiffening and embrittlement of the valve leaflets over time. This disadvantage generally leads to a reduced service life of the implanted prostheses.For this reason, alternative materials would be desirable that possess suitable mechanical and biological properties and can be manufactured in a standardized and reproducible manner. These materials should therefore not be made of animal materials, should not incorporate or accumulate any endogenous substances that impair function, and, ideally, should exhibit only small variations in their mechanical properties. Furthermore, it would be desirable if these prostheses could be used in minimally invasive procedures to protect the patient population. This could, for example, avoid open-heart surgery and significantly shorten recovery times.

[0004] Different technical solutions for valve prostheses are also described in the patent literature.

[0005] For example, WO 2010 124 219 A2 describes an expandable stent for use in implanting a valve prosthesis using a delivery system. The self-expandable stent comprises a tubular lattice structure defined by longitudinally aligned rods connected to V-shaped struts to form a plurality of interconnected, zigzag-shaped, six-sided polygons defining a distal end zone and a central zone of the tubular lattice structure. A flare or bend may be defined along the opposite ends of each rod to properly position the stent and valve prosthesis during deployment and placement of the stent within the lumen and to prevent inappropriate torsion.

[0006] Furthermore, WO 2010 020 660 A1 discloses an implantable valve prosthesis comprising at least one valve leaf and produced from a material structure of unidirectional reinforcing elements made of stretched ultra-high molecular weight polyolefin, running in at least two directions, wherein the reinforcing elements made of polyolefin have a modulus of elasticity of at least 60 GPa, characterized in that the material structure consists of exactly one woven or knitted mesh of the reinforcing elements made of stretched ultra-high molecular weight polyolefin.

[0007] A further embodiment is disclosed in EP 1 804726 B1. This describes a prosthetic heart valve for the functional replacement of a previously implanted prosthetic heart valve, wherein the prosthetic heart valve comprises a support structure (22); valve leaflets attached to the support structure; characterized by a device for coupling the prosthetic heart valve to a previously implanted prosthetic heart valve, wherein the coupling device is connected to the support structure.

[0008] Such solutions known from the prior art may offer further potential for improvement. This particularly relates to the functional and durable connection of valve materials to stent framework structures. It is therefore the object of the present invention to at least partially overcome the disadvantages known from the prior art. It is in particular the object of the present invention to provide a valve stent which is reversibly compressible and expandable and which fixes artificial valve structures reliably and in a mechanically gentle manner over extended periods of time. Furthermore, it is the object of the present invention to provide a valve prosthesis which can be implanted minimally invasively and which, due to the gentle connection of the valve structures, can provide a longer service life of the valve leaflets under cyclic loading.

[0009] The problem is solved by the features of the independent claims, directed to the valve stent according to the invention and the valve prosthesis according to the invention. Preferred embodiments of the invention are specified in the subclaims, in the description, or in the figures. Further features described or shown in the subclaims, in the description, or in the figures may constitute a subject matter of the invention, individually or in any combination, unless the context clearly indicates otherwise.

[0010] According to the invention, a valve stent for minimally invasive implantation in the human or animal body is therefore provided. The valve stent comprises at least one tubular, mechanically compressible and deployable stent framework with an inflow opening and an outflow opening and one or more receiving frames integrated into the stent framework for one or more valve leaflets, wherein the receiving frames for the valve leaflets are axially aligned in the lateral surface of the tubular stent framework and the total axial length H of the receiving frames is less than or equal to the distance from the inflow opening to the outflow opening of the valve stent, wherein a region of greater than or equal to 10% of the maximum length H of the receiving frame in the direction of the outflow opening is not arranged on the stent framework and is freely radially movable relative to the stent framework.Surprisingly, it was discovered that using the above-mentioned design, valve stents with valve leaflets can be provided. These can be implanted minimally invasively and the valve tissue can withstand a significantly higher number of load cycles without mechanical wear. This results in long-lasting valve prostheses that can be used with the greatest possible protection for the patient and that can remain in the human or animal body for a very long time without loss of original functionality. A further advantage of this design may be that the connection of the valve tissue to the stent is so advantageous that the valve tissue remains intact without the occurrence of tears in individual tissue components and therefore offers no further storage or deposition points for the body's own tissue or calcification.The reduced tendency for deposits can also increase the longevity of the valve stent. The design of the stent for securing the valve leaflets is also compatible with conventional stent manufacturing methods, allowing for the improved connection of the valve leaflets. Furthermore, the design of the stents allows for the secure fixation of many different valve leaflets, allowing for solutions tailored to specific application situations. Overall, this is more advantageous than current solutions, which either cannot be implanted minimally invasively or which, after periods of improvement, show signs of mechanical stress and calcium deposits on the valve leaflet.

[0011] The valve stent according to the invention is a valve stent for minimally invasive implantation into the human or animal body. A valve stent within the meaning of the invention is a stent that additionally functions as a valve. The valve function involves the stent being designed to open and close the stent passage for fluids. This valve function is performed, for example, by heart or venous valves in the human body. The valves are usually designed in the form of valve leaflets, which, depending on the flow through the valve, either contact one another with their leaflet edges and close the passage or, in an open configuration, allow the flow of fluids through the valve. The valve function is therefore performed by moving parts that are subject to very frequent mechanical load changes as a function of the opening frequency.The stent itself is typically a tubular structure which, for mechanical stabilization, is inserted into the human or animal body with its outer surface in contact with the vessel wall. Stents are available in various designs and are offered, for example, in the form of coated or uncoated, laser-cut metal tubes. Stents, and in particular the valve stent usable according to the invention, can be implanted minimally invasively. This means that for insertion of the valve stent into the respective body, the stent can be mechanically compressed (compressible) and only unfolded again at the site of deployment. The compression and unfolding of the stent, including the valve tissue arranged on the stent, can therefore be accomplished reversibly. The first step in stent implantation can, for example, be performed by creating an external access to the patient.For this purpose, a cannula is inserted into a vessel located close to the skin's surface. Under X-ray control, a guide catheter is then advanced toward the site of intervention, and the stent is placed there. The valve stent can thus be mechanically reversibly reduced in size so that it can be inserted into the human or animal body through a catheter.

[0012] The valve stent comprises at least one tubular, mechanically compressible, and deployable stent framework with an inflow opening and an outflow opening. The valve stent essentially has a cylindrical geometry, and the internal volume of the stent can be reversibly reduced and enlarged. The compressibility of the stent framework is usually achieved by not making the entire surface of the stent from one material. The stent can be provided, for example, in the form of a wire mesh or a laser-cut bar framework. The stent cylinder has two round or oval openings at its end faces. Depending on the use of the stent in the fluid flow under in-vivo conditions, a fluid volume flows through one opening of the stent first. This first opening is the inflow opening.The same volume of fluid, after flowing through the stent volume, reaches the second opening and exits the stent through this second opening. This second opening is the stent's outflow opening.

[0013] The valve framework contains one or more integrated receiving frames for one or more valve leaflets. To design a stent in the sense of a valve stent, the stent must contain additional devices that enable the connection of one or more valve leaflets. For this purpose, the valve stent according to the invention has one or more receiving frames in the valve framework, which interact with the material of the valve leaflets and fix them to the stent framework. The valve leaflet extends from the inside to the outside of the valve stent through the stent framework at the receiving frames. Essentially, flat structures made of various materials can be used as valve leaflets. For example, the use of natural materials such as collagen from the pericardium of pigs or cattle is known. However, synthetic materials, for example made of plastic, can also be used.In addition, it is also possible to use woven, knitted, or crocheted materials in the form of textile leaflets as valves. Textile ribbon fabrics can preferably be used for the valve stent according to the invention. The receiving frames for the valve leaflet(s) are integrated into the stent framework in that they are firmly connected to the framework of the stent. This can be achieved by firmly anchoring the receiving frames to the stent framework or, particularly preferably, by designing a part of the stent framework in such a way that it can serve as a receiving frame for the valve leaflets. In addition to fixing the valve leaflets in the receiving frames, the valve leaflets can of course also be arranged further along the stent framework, for example by sutures. The valve leaflets have a surface area that is mechanically fixed to the stent framework.Another part of the valve leaflets, however, is not fixed to the stent framework and is freely movable, so that this part can perform the function of opening and closing the valve. The stent framework can preferably have at least two, further preferably in particular three receiving frames for valve attachment. This higher number of receiving frames can be particularly advantageous in cases in which the valve is formed from several, for example three, individual valve parts, which are each individually fixed to one another and to the stent framework. A receiving frame can, for example, be in the shape of a narrow rectangle. The elongated connection points can then receive the valve leaflets, which are present in the form of more or less thin layers, for fixation to or in the stent framework.For this purpose, the valve leaflets are guided through the receiving frames from the inside and fixed to each other and to the stent frame outside the stent frame. This connection can be advantageous if several independent valve leaflet sections are fixed to each other and to the stent frame.

[0014] The receiving frames for the valve leaflets are aligned axially in the outer surface of the tubular stent framework. The cylindrical design of the tubular stent framework results in a stent outer surface that corresponds to a cylindrical surface. The receiving frames for the valves are located in this outer or cylindrical surface. This means in particular that the receiving frames do not protrude significantly inwards or outwards from the outer surface of the stent framework when mechanically unloaded. For example, it is possible for the receiving frames to extend cyclically by a maximum of 5 mm, preferably a maximum of 2.5 mm, and more preferably a maximum of 1 mm into the interior of the stent when the valve is closing and outwards, towards the vessel wall, when the valve is opening. The receiving frames extend parallel to the symmetry axis of the stent framework, i.e., they are essentially aligned along the stent framework from the inflow to the outflow opening.

[0015] The total axial length H of the support frame is less than or equal to the distance from the inflow opening to the outflow opening of the valve stent. The axial length H of the support frame is the maximum extension of the support frame from the inflow opening to the outflow opening. Thus, according to the invention, the support frame does not cover the entire distance from the inflow opening to the outflow opening of the valve stent.

[0016] An area greater than or equal to 10% of the maximum longitudinal extent H of the receiving frame in the direction of the outflow opening is not arranged on the stent framework and is freely radially movable relative to the stent framework. Although the receiving frame is part of the stent framework and is arranged in the tubular outer surface of the stent framework, it is not mechanically connected to the stent framework by struts evenly across its axial extent. While part of the receiving frame is firmly connected to the stent framework, part of the receiving frame is not connected to the stent framework. This area not connected to the stent framework is located in the direction of the outflow opening of the stent and this part is freely radially movable relative to the stent framework. According to the invention, at least a quarter of the maximum longitudinal extent H of the receiving frame is therefore not connected to the stent framework.In this case, the connection to the stent framework is established via the remaining maximum 90% of the receiving frame, which can be connected to the stent framework at specific points in the direction of the inflow opening or by transverse struts. The part not connected to the stent framework can therefore be almost freely movable relative to the stent framework. This free mobility arises in particular during cyclic tensile loading of the valve leaflet ends enclosed in the receiving frame during valve closure. The receiving frame can then be freely deflected radially inward relative to the stent framework, in the direction of the main axis of the forces occurring. In particular, a radial deflection of this part of the receiving frame can occur towards the interior of the stent and partly also towards the vessel wall. This part can therefore flexibly absorb forces from the moving valve leaflets and pass them on to the stent framework at the attachment points.This arrangement allows, in particular, the cyclic load peaks acting on the valve leaflets during valve closure to be mechanically compensated and the valve leaflet material in the area of ​​the connection to the receiving frames and the stent framework to be protected. By flexibly cushioning the mechanical forces occurring at the valve receptacles, the overall load can be reduced and, in particular, the peak load on the valve leaflets can be lowered. This protects the connection point and significantly increases the fatigue strength, i.e., a higher number of loading cycles, of the valve leaflets can be achieved. Preferably, an area of ​​greater than or equal to 20%, more preferably greater than or equal to 25% of the maximum linear extension H of the receiving frame in the direction of the outflow opening can be arranged not on the stent framework and can move freely radially relative to the stent framework.

[0017] In a preferred embodiment of the valve stent, an area greater than or equal to 50% of the length H of the receiving frame in the direction of the outflow opening can be located off the stent framework. For a particularly flexible and valve-protecting connection of the valve leaflets, free mobility of the upper 50% of the receiving frame has proven particularly suitable. In this area, the receiving frame lies in the outer surface of the stent framework, but is not connected to the stent framework by outflow-oriented longitudinal struts or tangential or oblique struts. The forces occurring when the valve leaflets open and close can be safely diverted to a large extent into the stent framework without causing excessive force to act on the upper part of the connection of the valve leaflets to the receiving frames and thus also on the stent framework.A significant portion of the support frame can swing freely radially, thus helping to reduce the mechanical forces on the valve leaflets.

[0018] In a further preferred embodiment of the valve stent, the receiving frame can be at least partially coated with a plastic or textile. Furthermore, it has proven particularly advantageous that the contact point between the valve leaflet and the stent is not designed as a metal contact. In particular, the connection of different valve leaflet materials to metal framework components of the receiving frame or stent can contribute to the valve leaflet materials being subjected to significant mechanical stress over time and yielding. By flexibly connecting the valve leaflets to the stent framework in combination with a textile or polymer buffer layer, a synergistic effect and thus longer service life of the valve stent under load can be achieved.

[0019] In a further preferred aspect of the valve stent, the receiving frame can be arranged at only one height position on the stent framework, at the height of the stent framework center. For the most flexible connection of the valve leaflets to the stent framework, a design in which the receiving frame is fixed to the stent framework at only one point has proven effective. In this design, the upper part can swing freely against the stent framework in the direction of the outflow opening. The lower part of the valve leaflet ends can be fixed to the stent framework by sutures. The latter can particularly contribute to the cells comprising the stent framework opening evenly upon expansion, thus extending the longevity of the stent-valve combination.

[0020] According to a preferred characteristic of the valve stent, the receiving frame can be arranged at two height positions on the stent framework, with the first height position being at the level of the inflow opening and the second height position being at the level of the stent framework center. To ensure safe and stable load absorption of the forces exerted on the valve leaflets, it has proven particularly advantageous for the receiving frame to be connected to the stent framework at two points. One of the points is located approximately towards or near the inflow opening, and the other connection point is approximately in the center of the stent framework. In this context, the stent framework center refers to the circumferential position on the cylinder, which is located on the circumference midway between the inflow and outflow openings. A positional deviation of approximately 10% in both directions based on the total stent height is still practical.Any additional connections between the receiving frame and the stent framework can, for example, be located between the two height positions described.

[0021] In a further preferred embodiment of the valve stent, the receiving frame can have a reversible maximum vibration amplitude of greater than or equal to 0.01 and less than or equal to 0.2 relative to the inner diameter of the stent frame relative to the stent frame. For a mechanically secure yet material-friendly connection of the valve material to the stent frame, the above-specified range of possible vibration amplitudes of the outflow edge of the receiving frame has proven particularly suitable. The maximum amplitudes of this edge are not too small, so that a relevant dissipation of the forces from the valve leaflets to the stent frame is ensured. However, the amplitudes are not too large, so that reliable and reproducible mobility (opening and closing) of the valve leaflets is ensured.The maximum amplitude results from the maximum deflection of the uppermost tip of the support frame, located on the flow side, relative to the tubular surface of the stent framework. For a valve to function for a good five years, the support frame must be able to withstand 200 million movements at this amplitude without breaking. The deflection of the support frame tip can be, for example, 0.5 mm / s.

[0022] In a preferred aspect of the valve stent, the shape of the receiving frame can, at least in sections, accommodate the symmetry of the stent framework at the same height position of the stent. For particularly favorable dissipation of the forces acting on the stent through the valve, it has proven particularly advantageous for the valve frame to not only have a symmetry suitable for connecting the valve leaflets. For purely receiving the usually flat valve leaflet materials, a rectangular frame or a slot in the stent framework is generally suitable. However, this symmetry of receiving and fixing the valve leaflets can advantageously be modified such that a non-slot-shaped symmetry is formed in certain areas of the receiving frame. For example, the lower part of the receiving frame towards the inflow opening can preferably have a diamond or honeycomb symmetry.This is particularly advantageous in cases where the stent also exhibits diamond or honeycomb symmetry in these areas within the stent framework. In conjunction with additional sutures made of non-absorbable suture material, preferably connecting two adjacent cells (honeycombs) of the stent framework to the valve leaflet ends, this design can both securely hold the valve leaflets and ensure a particularly symmetrical force introduction into the rest of the stent framework for compression and redeployment during implantation. Examples of this embodiment are given further down in the figures.

[0023] Furthermore, the invention relates to a valve prosthesis comprising a valve stent according to the invention and at least one valve leaflet, wherein the valve leaflet comprises a ligamentous fabric. The advantages of the valve prosthesis according to the invention arise in particular from the inventive interaction and the connection of the valve leaflets to the stent framework to form a valve prosthesis. In this context, reference is made to the advantages of the valve stent in conjunction with the insertable valve leaflets. These advantages can be particularly significant in cases where the valve leaflets are not made from a single piece. The valve can consist of several valve leaflets, which can be fixed to one another on several receiving frames and, if necessary, also on the stent framework.By fixing the valve components to one another, which occurs primarily at the receiving frames, a mechanically stable construct can be created that can withstand high forces and, in particular, frequent oscillation cycles much better. The inventive structure, consisting of a valve stent and valve leaflet made of ligamentous fabric, has proven particularly advantageous. Due to their mechanical structure, ligamentous fabrics are particularly suitable for connection to the stent framework using partially freely swinging receiving frames. This allows for a high degree of freedom in the physical properties of the ligamentous fabric, which would otherwise not be possible due to the mechanical stress at the stent connection points. This opens up the possibility of developing other ligamentous fabric types, and for existing ligamentous fabric types, the fatigue strength under cyclic oscillation can be significantly extended.In a preferred embodiment, the valve leaflet can consist of warp threads and at least one weft thread, wherein the warp threads are aligned radially and the weft thread(s) are aligned axially with respect to the lateral surface of the tubular stent framework, wherein the alignment of the warp threads directly on the receiving frame assumes an angle of greater than or equal to 60° and less than or equal to 90° with respect to the axial axis of symmetry of the receiving frame. It has proven particularly advantageous if, when using ribbon fabrics, these have a specific alignment with the receiving frame. This alignment arises in cases in which the warp thread(s) run essentially radially, i.e. essentially parallel to the circular surface of the stent, and enter the receiving frame in this alignment. Under load, the warp threads can move in the direction of the inflow or outflow opening, but this movement only minimally affects the angular alignment directly on the receiving frame.The weft thread(s) of the ribbon fabric run axially, i.e. approximately parallel to the central axis of the stent. The weft threads are arranged at an angle of 90° + / - 10° relative to the warp threads in the ribbon fabric. The specified angle range indicates possible angular deviations of the warp threads from the preferred geometry. An angle of less than 90° indicates that the warp threads may not be vertical, but rather inclined slightly towards the inflow opening. This orientation results from the arrangement in the stent, particularly in relation to the receiving frame, with the warp threads in the ribbon fabric running into the receiving frame in an approximately vertical orientation relative to the axial orientation of the receiving frame. The weft threads then extend accordingly approximately parallel to the stent central axis or, in the upper downstream area, inclined by up to 30° in the direction of the stent central axis relative to the axial axis of symmetry of the receiving frame.

[0024] In a further preferred embodiment, the valve leaflet can consist of warp threads and at least one weft thread, wherein the warp threads are aligned radially, particularly in their upper attachment region, to the receiving frame of the stent, for example at a height of 10-40% H, preferably 25% H, and the weft threads are aligned axially with respect to the lateral surface of the tubular stent framework, wherein the alignment of the warp threads at the connection point to the axially arranged receiving frame assumes an angular range of greater than or equal to 60° and less than or equal to 90°, wherein the range less than 90° describes an angulation in the direction of the inflow opening of the valve prosthesis. The attachment of the valve leaflets made of warp threads and weft threads to the receiving frame in the described orientation can, however, also comprise up to 100% H.

[0025] The decisive factor for fatigue strength and thus for the feasibility of a heart valve with synthetic leaflets is the permanent attachment of the leaflet attachments to the upper commissures of the valve ring. The critical cycle phase with the highest tensile stresses is diastole (= phase of valve closure), since a blood column with a pressure of approximately 100 mm Hg presses on the leaflets. The inventive solution results from the force introduction of the critical tensile stresses from the leaflet surface into the upper commissure region of the valve ring, i.e. into the receiving frame, via a number of parallel warp threads of the woven fabric used, which consists entirely of warp and weft threads. The solution results synergistically from a specific orientation of the warp threads in the receiving frame and its elastic, freely oscillating property.Both features enable better bonding of the ligament tissue to the stent structure, optimal load-bearing capacity, and thus improved durability even under high mechanical stress. This enables medically acceptable and commercially attractive fatigue strength. The weft threads ensure uniform spacing of the warp threads, and the warp threads absorb the majority of the tensile stress when the valve leaflet is closed, particularly the peak tensile stress during the valve weft phase.

[0026] The force introduction of the valve leaflet's tensile stress into the supporting stent occurs via the approximately perpendicular connection (or by bending it by up to 60° in the direction of the inflow opening) of parallel warp threads of the valve leaflet fabric with the support frames. As an additional feature, a self-supporting, resiliently deflectable design of the support frames reduces cyclical tensile load peaks during valve closure. This force introduction into resilient support frames can be particularly effective in cases where the warp threads consist of or comprise a high-tensile polymer material, such as UHMWPE. Furthermore, the tape fabric can be particularly suitable if it includes a free leaflet edge, which can be achieved by reversing the weft threads.

[0027] In a further preferred embodiment of the valve prosthesis, the valve leaflets can be formed from at least two ligamentous fabrics arranged relative to one another, and the valve stent can have at least two receiving frames, with two ligamentous fabric ends each being enclosed by a receiving frame and arranged relative to one another. Embodiments with several ligamentous fabrics arranged relative to one another can have particularly favorable mechanical properties in conjunction with partially freely swinging receiving frames. The individual ligamentous fabrics can be securely fixed relative to one another on the receiving frames, and the loads are transferred particularly effectively from the individual ligamentous fabrics in the valve region to the stent framework. Both can significantly improve the longevity of the prostheses under in vivo conditions.

[0028] In a further preferred aspect of the valve prosthesis, the ligamentous tissues can be sewn together. In addition to a possible mechanical fixation against the stent framework, it has proven particularly advantageous for the ligamentous tissues to be sewn against or to one another at their ends in the region of the receiving frames. Due to the mutual mechanical fixation, the individual ligamentous tissues can move at least partially independently of one another and maintain mechanical cohesion only in the region of the receiving frames. Sewing has proven advantageous in this context, as it is flexible and secure enough to absorb the occurring mechanical forces. According to a preferred characteristic of the valve prosthesis, the ligamentous tissues can be glued to one another.In addition to possible mechanical fixation to the stent framework, it has proven particularly advantageous for the ligamentous tissues to be bonded to or against each other at the respective ends of the ligamentous tissue in the area of ​​the receiving frames. This mutual chemical fixation allows the individual ligamentous tissues to move at least partially independently of each other, maintaining their cohesion only in the area of ​​the receiving frames. Adhesive bonding has proven advantageous in this context, as it is flexible and secure enough to absorb the resulting mechanical forces.

[0029] In a preferred aspect of the valve prosthesis, one or more axially extending plastic or metal reinforcements can be attached in or at the contact point of the ligamentous tissue outside the stent's internal volume. For flexible adaptation of the stiffness of the contact surfaces of the individual valve leaflet components in the area of ​​the receiving frames, it has proven advantageous to insert reinforcements in the form of rods or tubes adjacent to the outer surface of the stent framework. The rods or tubes can be attached before the valve leaflets are fixed to one another, between or at the fixation or direct contact point of different valve components. The reinforcements can have a homogeneous stiffness across the entire reinforcement.In principle, however, it is also possible for the reinforcements to exhibit inhomogeneous stiffness, with, for example, the upper part of the reinforcement toward the outlet opening being more elastic than the lower part. This allows for particularly precise adjustment of force absorption and force transmission, regardless of the valve leaflet material used.

[0030] Further advantages and advantageous embodiments of the inventive objects are illustrated by the figures and explained in the following examples. It should be noted that the figures are for descriptive purposes only and are not intended to limit the invention in any way.

[0031] The

[0032] Fig. 1 shows a stent framework for a valve stent according to the state of the art;

[0033] Fig. 2 shows schematically an embodiment of a valve stent according to the invention in the unfolded state in a section;

[0034] Fig. 3 shows schematically an embodiment of a valve stent according to the invention in the compressed state in a section;

[0035] Fig. 4 shows schematically an embodiment of a valve stent according to the invention in the unfolded state in a section;

[0036] Fig. 5 schematically shows an embodiment of a valve stent according to the invention in the compressed state in a section,

[0037] Fig. 6 shows schematically an inventive connection of a band fabric to a receiving frame of a stent according to the invention;

[0038] Fig. 7 schematically shows the angular relationship of the warp threads of a ribbon fabric on a receiving frame of a stent according to the invention;

[0039] Fig. 8 schematically shows a combination of a stent according to the invention and a ligamentous fabric connection thereto according to the invention;

[0040] Fig. 9 schematically shows a combination of a stent according to the invention and the connection of a band fabric to it according to the invention.

[0041] Figure 1 shows a stent framework 2 for a valve stent according to the prior art, as disclosed in US 2020 / 0146815. The stent framework 2 is shaped like a tube. The inflow opening 4 is located on the lower side of the stent framework 2, and the outflow opening 5 is located on the other, upper side. The stent framework 2 has a receiving frame 3 to which the valve leaflets (not shown) can be attached. The receiving frame 3 is connected to the stent framework 2 both in the direction of the inflow opening 4 and in the direction of the outflow opening 5.

[0042] Figure 2 schematically shows a section of an embodiment of a valve stent 1 according to the invention in the deployed state. For example, the stent framework can be deployed in a vessel. A portion of the stent framework 2 is shown. The stent framework 2 can, for example, be laser-cut from a metal tube, resulting in a framework 2 made of metal struts. Due to its structure, the stent framework 2 is reversibly compressible and deployable and can be implanted minimally invasively into the human or animal body using a catheter. The stent framework 2 has an inflow opening 4 and an outflow opening 5. The definition of the inflow and outflow results from the flow direction of the fluid flowing through the stent.For attaching a valve leaflet 6, for example in the form of one or more valve leaflets 6 (here in the form of, for example, two valve leaflet ends arranged next to one another) made of a fabric, the stent framework 2 has a receiving frame 3 (shown in dashed lines) to which parts of the valve leaflet 6 or the valve leaflets 6 can be attached. The stent framework 2 can have one, two, preferably three or more receiving frames 3. A part of the valve leaflet material can be guided to each of these receiving frames 3 from the inside of the stent through the receiving frame 3 to the outside of the stent and fixed from the outside to the stent framework 2. If the valve is formed from several valve leaflets 6, the individual valve leaflet ends can be attached to the receiving frame 3 against one another and / or to the stent framework 2. The attachment can be achieved, for example, by sewing 7 or by gluing.The receiving frame 3 is aligned axially in the lateral surface of the stent framework 2 and does not extend over the entire length from the inflow opening 4 to the outflow opening 5. In the axial alignment, the receiving frame 3 assumes a maximum longitudinal extent H. Figure 2 shows that the receiving frame 3 is not arranged evenly on the stent framework 2. The receiving frame 3 is only arranged on the stent framework 2 in the lower area towards the inflow opening 4 and in the middle area. The upper quarter of the receiving frame 3 towards the outflow opening 5, however, is not arranged on the stent framework 2 and is more freely movable than the fixed part. Due to the fact that the valve leaflet 6 is exposed to mechanical forces during opening and closing, if the valve leaflet 6 is rigidly connected to the stent framework 2, the valve leaflet material can tear if subjected to excessive stress.The freely swinging connection of the valve leaflets 6 to the stent framework 2 by the upper support frame 3 partially compensates for the mechanical forces that occur, preventing mechanical failure of the valve leaflets 6 in the area of ​​the connection to the stent framework 2. This can extend the fatigue strength of the valve stent 1 under load. Preferably, the valve material 6 can be made of several, for example, three separate, woven bands, the ends of which are fixed to each other in pairs on three support frames 3 and to the stent framework 2.

[0043] Figure 3 schematically shows a section of an embodiment of a valve stent according to the invention in the compressed state. This figure shows a valve stent 1 with the same structure as Figure 2. As in Figure 2, this figure shows the stent framework 2, the inflow opening 4, the outflow opening 5, the receiving frame 3, and the valve leaflet 6. The valve stent 1 can be placed in this compressed form into a catheter and introduced into the body through this catheter in a minimally invasive manner. This figure also shows that the valve leaflet 6 is sutured to the stent framework 2 at two additional suture positions 7.

[0044] Figure 4 schematically shows a further embodiment of a valve stent 1 according to the invention in a deployed state in a section. In this figure, as in Figure 2, the stent framework 2, the inflow opening 4, the outflow opening 5, the receiving frame 3, and the valve leaflets 6 are shown. The receiving frame 3 extends axially in the lateral surface of the stent framework 2 and is only connected to the stent framework 2 at two positions. The receiving frame 3 does not extend to the inflow opening 4 of the stent framework 2. Just as in Figure 2, the receiving frame 3 is firmly connected to the stent framework 2 at two points.

[0045] Figure 5 schematically shows a section of an embodiment of a valve stent according to the invention in the compressed state. As in Figure 4, this figure shows the stent framework 2, the inflow opening 4, the outflow opening 5, the receiving frame 3, and the valve leaflets 6.

[0046] Figure 6 schematically shows an inventive connection of a woven band 7 to a receiving frame 3 of a stent 1 according to the invention. In this figure, it can be seen that the warp threads 8 are arranged approximately vertically, i.e. at approximately 90°, relative to the axial alignment of the receiving frame 3. The receiving frame 3 is not arranged on the stent framework 2 in the upper region, so that this region can swing freely when the valve leaflet closes. In particular, the 90° alignment of the warp threads 8 means that the mechanical stresses that occur when the valve closes can be absorbed particularly well. The combination of leaflet connection and stent structure results in the prosthesis having a significantly longer service life. This advantage is particularly evident in comparison to commonly used materials, such as collagen but also other synthetic materials.The weft thread(s) 9, however, run approximately axially to the stent structure and also in relation to the receiving frame 3. The weft thread(s) 9 ensure mechanical fixation and uniform spacing of the warp threads 8.

[0047] Figure 7 schematically shows the angular relationship of the warp threads 8 of a woven band 7 on a receiving frame 3 of a stent 1 according to the invention. The warp threads 8 can form an angle of approximately 60° to 90° with respect to the receiving frame 3. Preferably, the angle can be greater than or equal to 70°, and more preferably greater than or equal to 80°. In these orientations, the woven band 7 can absorb the forces occurring particularly well in combination with a freely oscillating receiving frame 3 and can lead to extended service life even under high mechanical loads.

[0048] Figure 8 schematically shows a combination of the stent 1 according to the invention and the inventive connection of a woven band 7. The receiving frame 3 of the stent 1 is a resilient receiving frame, wherein the receiving frame 3 is not arranged on the stent framework for approximately 10-100% of its total height H and oscillates freely. In combination with the inventive arrangement of the woven band 7 on the stent 1, peak tensile loads are dampened during valve closure.

[0049] Figure 9 schematically shows a combination of the stent 1 according to the invention and the inventive connection of a band fabric 7 to it. In this embodiment, it can be seen that only the upper portion of the warp threads 8 runs radially into the receiving frame 3. In this area, the angular orientation of the warp threads 8 to the axial axis of symmetry of the receiving frame 3 is approximately 90°. The lower portion of the warp threads 8 can, for example, be attached tangentially to the stent 1. The receiving frame 3 of the stent 1 is a resilient receiving frame, wherein the receiving frame 3 is not arranged on the stent framework for approximately 10 - 100% of its total height H and oscillates freely. In combination with the inventive arrangement of the band fabric 7 on the stent 1, tensile load peaks during valve closure are dampened. The warp threads 8 that pass by are not directly attached to the receiving frame 3 and can therefore have a different angular orientation.

Claims

Patent claims 1. Valve stent (1) for minimally invasive implantation in the human or animal body, at least comprising a tubular, mechanically compressible and deployable stent framework (2) with an inflow opening (4) and an outflow opening (5) and one or more receiving frames (3) integrated in the stent framework (2) for one or more valve leaflets, characterized in that the receiving frames (3) for the valve leaflets (6) are aligned axially in the lateral surface of the tubular stent framework (2) and the total axial length H of the receiving frames (3) is less than or equal to the distance from the inflow opening (4) to the outflow opening (5) of the valve stent (1), wherein an area of ​​greater than or equal to 10% of the maximum length H of the receiving frame (3) in the direction of the outflow opening (5) is not arranged on the stent framework (2) and is free with respect to the Stent frame (2) is radially movable.

2. Valve stent according to claim 1, wherein a region of greater than or equal to 50% of the length H of the receiving frame (3) in the direction of the outflow opening (5) is not arranged on the stent framework (2).

3. Valve stent according to one of the preceding claims, wherein the receiving frame (3) is at least partially coated with a plastic or a textile.

4. Valve stent according to claim 2, wherein the receiving frame (3) is arranged in only one height position at the height of the stent frame center on the stent frame (2).

5. Valve stent according to claim 2, wherein the receiving frame (3) is arranged in two height positions on the stent framework (2), the first height position being at the height of the inflow opening (4) and the second height position being at the height of the stent framework center.

6. Valve stent according to one of the preceding claims, wherein the receiving frame (3) has a reversible maximum vibration amplitude of greater than or equal to 0.01 and less than or equal to 0.2 relative to the inner diameter of the stent frame (2) relative to the stent frame (2).

7. Valve stent according to one of the preceding claims, wherein the shape of the receiving frame (3) at least partially accommodates the symmetry of the stent framework (2) in the same height position of the valve stent (1).

8. Valve prosthesis comprising a valve stent (1) according to one of claims 1 to 7 and at least one valve leaflet (6), wherein the valve leaflet (6) comprises a ligamentous fabric (7).

9. Valve prosthesis according to claim 8, wherein the valve leaflet (6) consists of warp threads (8) and at least one weft thread (9), wherein the warp threads (8) are aligned radially and the weft thread(s) (9) are aligned axially with respect to the lateral surface of the tubular stent framework (2), wherein the alignment of the warp threads (8) directly on the receiving frame (3) forms an angle of greater than or equal to 60° and less than or equal to 90° with respect to the axial axis of symmetry of the receiving frame (3).

10. Valve prosthesis according to claim 9, wherein the valve leaflets (6) are formed from at least two band fabrics (7) arranged relative to one another and the valve stent (1) has at least two receiving frames (3), wherein two band fabric ends are each enclosed on a receiving frame (3) and arranged relative to one another.

11. Valve prosthesis according to claim 10, wherein the ligamentous tissues (7) are sewn together.

12. Valve prosthesis according to claim 10, wherein the ligamentous tissues (7) are glued together.

13. Valve prosthesis according to one of claims 10-12, wherein one or more axially extending plastic or metal reinforcements are mounted in or at the contact point of the ligamentous fabrics (7) outside the stent internal volume.

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