BACKGROUND

This disclosure relates to the field of producing an improved valve, which can be used in veins, arteries and other body ducts.

In natural valves cells that are connected to the duct wall generally develop the flexible valve membranes. This is logical, because if there were no connection to the wall, the membrane would not receive the necessary elements, building materials and nutrition to grow and maintain its properties during lifetime. Further a valve membrane would float away with the body fluid if it were not directly connected to the wall. Consequently, in natural body valves the fluid will always flow through the aperture that opens up when the membrane takes its open position. This means that the main flow basically is centered in the body duct and that the deforming valve membrane is plied against or nearer to the wall.

Prosthetic valves can be implanted by means of surgery or by minimal invasive techniques using catheter-like devices.

In the first category there are several mechanical systems with a more rigid moving part, like a ball valve or rotating hinged plates. Examples of these devices are single and double flap designs, manufactured by companies as Abbott, Medtronic, Sulzer, Liva Nova and others. Some of the main disadvantages of these devices are a need for permanent treatment of anticoagulants, noisy operation, and a need for a large-scale operation to implant.

Deformable valve materials form another category. There is a wide range of biologically based valves made of natural valves or composed of biological materials such as percardial tissue. Well-known companies such as Edwards Lifesciences, Medtronic, Sulzer, Liva Nova and others too market these.

Polymer valves are new and several companies are in the process of developing such products. A polymer for such valves could be the well-known polyurethane.

Such prosthetic valves are generally making use of a support frame and the flexible membrane that works as the actual deforming valve. In these valves the membrane is directly connected at the annular base and struts to the supporting frame by stitching, gluing, dipping, welding etc. This also means that the flow is not directly guided along the inner surface of the supporting frame, but merely through the center of the duct. In some cases the covered inner surface of the support frame has the risk of closing the entrance of side lumens, for example a coronary artery which descends from the aorta. This means that accurate placement is very critical.

The construction with a membrane directly connected to the support frame also creates the risk of zones, where the blood flow is not smooth enough, which may cause thrombosis and/or platelet deposition. Such problems should be avoided by making an appropriate design, in which the body fluids can easily flush around all valve parts, avoiding too much turbulence or dead zones with no or not enough flow.

U.S. 20030114913 discloses a valve prosthesis, which can be delivered by means of a balloon catheter. The flexible valve membrane is located inside a balloon expandable stent ring and attached thereto by means of stitches. The valve tissue is at the same axial location as the supporting stent frame.

Examples of similar designs with the valve placed inside a self-expandable or balloon-expandable stent are disclosed in numerous patents, for example U.S. Pat. Nos. 6,503,272; 6,458,153; 6,027,525; 5,957,949 and 5,855,601.

In the case of a balloon expandable stent, the delivery balloon, mounted near the distal end of a long catheter, is essentially placed inside the stent frame and thus also inside the same area where the folded membrane is located. This causes a pile up of several materials, all adding to the insertion profile of the device. The stent and all materials inside it are crimped as much as possible on the catheter, but this is limited by the minimal required thickness of stent struts, membrane, balloon material and catheter core. Damage to the membrane must be avoided, so crimping forces should be limited as well. Also the radial pressure that is exerted to the membrane, while the balloon is inflated to expand the stent, may cause damage to the fragile membrane material. In fact the membrane is squeezed between the balloon and the inner stent wall.

In other devices, like for example the one disclosed in U.S. 20020188348 the valve is not situated inside the supporting frame. Here the support frame has elongated struts, which are covered with a series of valve leafs. The elongated struts move together with the attached valve leafs when the valve opens and closes. In this design, like in the previous ones, the blood flow always goes through the center part of the valve.

In general, if a valve opens in the center, while the flaps are moving outside, the cross section that allows blood flow is determined by the total surface area that the cross section of the support frame, inside layer covering the support structure plus valve flaps occupy. Suppose that the open valve has a circular opening and that in an open state the valve flap tips move from the center over a maximum distance of half the body lumen radius. They would than give only a circular area with half the body lumen diameter free. In such a case only 25% of the total surface area of the body lumen is then open.

However, this means that 75% of the surface area is not available for blood flow. It would therefore be better to use a valve, which does not open in the center, but instead allows the blood to flow around it. With the same movement of the valve flap tips over half the radius, but now with flaps moving from the body lumen wall inward, the effective surface area becomes 75% instead of 25%. Therefore it may be better to design valves that allow the body fluid to flow around them instead of through them.

Another disadvantage of valves with the valve membrane attached to the wall is that during lifetime new cells may grow onto the membrane surface. These cells could grow from the body lumen wall and gradually cover parts of the membrane tissue, or even the entire membrane. This contamination can hinder a proper functioning of the valve or even cause major problems over time.

If the valve membrane was not in direct contact with the body lumen wall the contamination with new growing cells on the membrane tissue is much less likely.

Not only new cells may cause contamination of the heart valve. Another problem is that platelet adhesion and collection of emboli may occur on sites where the flow is very low. This can be caused if there are “dead zones” in the flow pattern. It is therefore essential to design a valve that is automatically kept clean by the blood flow, which can reach the entire valve surface.

SUMMARY

The present disclosure provides a series of new concepts in the field of aortic valves and other human valves. Such valves are suitable for conventional placement by surgery, but especially optimized for the more favorable percutaneous implantation.

It is an object of the disclosure that a stented prosthetic valve comprises a flexible membrane, held in a body duct by means of a support frame, whereby the membrane can collapse in order to allow a flow around it, passing through the openings between the membrane surface and the inner wall of the duct.

Another object of the disclosure is that the valve membrane closes the valve by expanding towards the wall of the duct, instead of valves that open by expansion towards the wall.

Still another object of the disclosure is that the valve membrane movements are caused by a combination of pressure, elasticity of the membrane itself and elasticity of additional elements connected thereto.

It is also an object of the disclosure that the support frame may be placed by surgery or by minimal invasive techniques, comprising the use of a balloon catheter with a balloon expandable frame or by delivery of a self-expanding frame from a sheath, followed by post-dilatation.

Another object of the disclosure is that by a proper dimensioning of the valve membrane a flushing of the membrane surface will automatically keep it clean on all sides.

Still another object of the disclosure is the use of an additional one-way valve in the tip of the device to flush the blood from the membrane surface to prevent contamination and cell adhesion.

It is also an object of the disclosure that the surfaces of the stented prosthetic valve can be treated with one or both of a coating and additional drugs to improve the characteristics or to lower the chance on problems during use.

It is further another object of the disclosure that by variation of the type of stent, the placement can be done by balloon expansion, self-expansion, balloon triggerable self-expansion, balloon expandable light curing stent surfaces and combinations thereof.

It is another object of the disclosure that the flexible membrane of the valve is reinforced with fibers with high tensile strength and high flexibility, and/or that the membrane is given shape control by embedding or connection of elastic fibers or struts.

Another object of the disclosure is that the membrane edges may be bulged or have protuberant edges to improve the sealing characteristics of the membrane when it is pressed against the lumen wall or any layer covering the inside wall of the stent.

It is also an object of the disclosure that the valve is placed either downstream from, upstream from or inside the supporting stent and that more than one valve may be placed.

It is further another object of the disclosure that the flexible membrane may be made of any polymer, metal, organic tissue, fabric or combinations thereof.

Another object of the disclosure is that the stent and the support frame for the flexible membrane are made of metal, polymer, and combinations thereof.

Another object of the disclosure is that the shape and number of struts, supporting and connecting the frame is variable, depending of the use of the valve.

It is also another object of the disclosure that the stent may be provided with hooks to hold it secured in the body lumen.

It is another object of the disclosure that the valve needs less valve movement to reach a certain surface area available to let blood pass.

Another object of the disclosure is that less valve movement at the leaflet folding area will lead to less structural fatigue and failure of the valve membrane material.

Still another object of the disclosure is that the valve holder frame may have flared ends in order to enable a secure fixation in the annulus of the native aortic valve.

Another object of the disclosure is that the moving leaflets of the valve membrane close against a separate polymer skirt or skin that is mounted on the valve holder frame to act as a sealing edge.

It is also an object of the disclosure that the valve edge closes against a separate skirt at a diameter that is smaller than the maximum diameter of the support frame.

It is further another object of the disclosure that the valve leaflets need less movement for creating the same opening surface, compared with valves that open in the center.

It is also an object of the disclosure that the valve construction leads to less structural fatigue and failure of the leaflets, compared with valves that open in the center.

Another object of the disclosure is that one or more valves and their support frames are mounted on a catheter carrying an intra-aortic balloon pump with at least one repeatedly inflatable and deflatable balloon.

Another object of the disclosure is that the two or more one way valves and at least one balloon are combined in any configuration in order to reach effects comprising optimizing the blood flow, limiting whipping by the balloon, keeping the balloon in the center of the aorta, maintaining the axial position of the catheter, limiting energy losses, enabling the use of smaller balloons for the same flow.

It is also an object of the disclosure that an assembly with a first conical valve membrane with a first top angle and a second conical membrane with a second top angle are mounted to the same frame, wherein both membranes are attached to each other at the cone base, thus acting together as an one way valve and wherein the intermediate space enclosed by both membranes is in direct contact with the lumen of the catheter that carries the device, so that raising the pressure in the intermediate space causes closure of the valve independent of the actual pressure difference over the valve caused by the heart beating.

Still another object of the disclosure is that a prosthetic aortic valve is assembled from an inner expandable valve holder frame with valve holder struts and a conical valve membrane connected thereto, an outer annulus holder frame and an adaptive sealing skirt that prevents paravalvular leakage between both frames.

It is also an object of the disclosure that the outer annulus holder frame has a flared end at the upstream side.

It is further another object of the disclosure that the outer annulus holder frame has a flared end at the downstream side.

Another object of the disclosure is that the flared end at the downstream side of the annulus holder frame has a three-lobed shape to accommodate to the anatomy of the aortic sinuses.

Still another object of the disclosure is that the double frame construction with a second surrounding support frame and a valve holder frame is used in other locations in the human body.

Another object of the disclosure is that the amount of cells in tangential and axial directions in the support frames may be varied, dependent on the place of use.

