Patent Publication Number: US-2018028315-A1

Title: Valve apparatus, system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent Ser. No. 15/154,302, filed May 13, 2016, which is a continuation of U.S. patent application Ser. No. 12/957,039, filed Nov. 30, 2010, which is a continuation of U.S. patent application Ser. No. 11/063,681, filed Feb. 23, 2005, now U.S. Pat. No. 7,867,274 which is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to apparatus, systems, and methods for use in a lumen; and more particularly to a valve apparatus, systems, and methods for use in the vasculature system. 
     BACKGROUND OF THE INVENTION 
     The venous system of the legs uses valves and muscles as part of the body&#39;s pumping mechanism to return blood to the heart. Venous valves create one way flow to prevent blood from flowing away from the heart. When valves fail, blood can pool in the lower legs resulting in swelling and ulcers of the leg. The absence of functioning venous valves can lead to chronic venous insufficiency. 
     Techniques for both repairing and replacing the valves exist, but are tedious and require invasive surgical procedures. Direct and indirect valvuoplasty procedures are used to repair damaged valves. Transposition and transplantation are used to replace an incompetent valve. Transposition involves moving a vein with an incompetent valve to a site with a competent valve. Transplantation replaces an incompetent valve with a harvested valve from another venous site. Prosthetic valves can be transplanted into the venous system, but current devices are not successful enough to see widespread usage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1B  illustrate an embodiment of a valve. 
         FIG. 1C  illustrates a cross-sectional view of the valve illustrated in  FIG. 1A  taken along plane  1 C- 1 C. 
         FIG. 1D  illustrates a cross-sectional view of the valve illustrated in  FIG. 1B  taken along plane  1 D- 1 D. 
         FIGS. 2A-2D  illustrate segment views of embodiments of a cover. 
         FIGS. 3A-3B  illustrate a valve in an expanded and a collapsed state. 
         FIG. 4  illustrates an embodiment of a system that includes a valve. 
         FIG. 5  illustrates an embodiment of a system that includes a valve. 
         FIG. 6  illustrates an embodiment of a system that includes a valve. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention are directed to an apparatus, system, and method for valve replacement or augmentation. For example, the apparatus can include a valve that can be used to replace or augment an incompetent valve in a body lumen. Embodiments of the valve can include a frame and cover that can be implanted through minimally-invasive techniques into the body lumen. In one example, embodiments of the apparatus, system, and method for valve replacement or augmentation may help to maintain antegrade blood flow, while decreasing retrograde blood flow in a venous system of individuals having venous insufficiency, such as venous insufficiency in the legs. 
     The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 110 may reference element “10” in  FIG. 1 , and a similar element may be referenced as  210  in  FIG. 2 . As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, and/or eliminated so as to provide a number of additional embodiments of valve. In addition, discussion of features and/or attributes for an element with respect to one Fig. can also apply to the element shown in one or more additional Figs. 
       FIGS. 1A-1D and 3A-3B  provide illustrations of various embodiments of a valve of the present invention. Generally, the valve can be implanted within the fluid passageway of a body lumen, such as for replacement or augmentation of a valve structure within the body lumen (e.g., a venous valve). In one embodiment, S the valve of the present invention may be beneficial to regulate the flow of a bodily fluid through the body lumen in a single direction. 
       FIGS. 1A-1D  illustrate one embodiment of a venous valve  100 . Venous valve  100  includes a frame  102 , a first leaflet  104  and a second leaflet  106  formed from a cover  108 , where the frame  102  and the leaflets  104  and  106  can resiliently radially collapse and expand, as will be discussed herein. Among other things, the frame  102  and the leaflets  104  and  106  define a lumen  110  of the valve  100 . The lumen  110  allows for, among other things, fluid (e.g., blood) to move through the valve  100 . 
     The frame  102  also includes a first end  112  and a second end  114 . The first end  112  and the second end  114  define a length of the frame  102  and of the valve  100 . In one embodiment, the length of valve  100  can have a number of values. As will be appreciated, the length of valve  100  can be determined based upon the location into which the valve  100  is to be implanted. In other words, the length of the valve  100  can be patient specific. Examples of values for the length include 4 millimeters to 30 millimeters. 
     The frame  102  further includes an outer surface  116  and an inner surface  118  opposite the outer surface  116 . In one embodiment, the cover  108  can be located over at least a portion of the outer surface  116  of the frame  102 . For example, the cover  108  can extend around a perimeter of the frame  102  so as to cover the outer surface  116  of the frame  102 . In other words, the cover  108  can extend over the outer surface  116  of the frame  102  so as to limit, or eliminate, exposed portions of the outer surface  116  of the frame  102 . In an additional embodiment, the cover  108  can be located over at least a portion of the inner surface  118  of the frame  102 . A further embodiment includes the cover  108  located over at least a portion of the outer surface  116  and the inner surface  118 . 
     The leaflets  104  and  106  further include surfaces defining a reversibly sealable opening  120  for unidirectional flow of a liquid through the lumen  110  of the valve  100 . For example, the surfaces of the leaflets  104  and  106  can be deflectable between a closed configuration in which fluid flow through the lumen  110  can be restricted and an open configuration in which fluid flow through the lumen  110  can be permitted. 
     The cover  108  further includes a physical configuration that provides support to the shape and structure of the leaflets  104  and  106 . As used herein, physical configurations that provide “support” can include structures and/or members that are integrated into and/or a part of the material that composes the cover  108  that help to maintain a pre-implant shape and size of the leaflets of the valve. 
     The physical configuration that provides support to the leaflets  104  and  106  can be provided in a number of ways. For example, the cover  108  can include a matrix  122  reinforced with flexible support members  124  to provide a composite structure for the leaflets  104  and  106 . The flexible support members  124  can be integrated into the matrix  122  so as to help prevent deformation of the original size and shape of the leaflets  104  and  106  that may occur over time through such processes as material stretch, creep, and stress relaxation. So, for example, the integrated flexible support members  124  can be oriented to provide circumferential support to the first leaflet and the second leaflet  104  and  106 . 
     In one embodiment, the cover  108  can have a multi-layer configuration in which at least one layer of the integrated flexible support members  124  can be integrated and/or laminated between at least one layer of the matrix  122  material. For example, as illustrated in  FIGS. 1A-1D , the cover  108  includes one or more layers of the flexible support members  124  and one or more layers of the matrix  122  that contribute to enhanced mechanical and handling properties of the cover  108 . As discussed herein, the layers of the flexible support members  124  can be positioned to lie in a number of different relationships to each other. For example, the layers of the flexible support members  124  can lie in coplanar relations to one another, where the layers can have a number of angular relations to one another (e.g., orthogonal relation to each other). Other configurations are also possible. 
     As illustrated, the leaflets  104  and  106  can also have an integrated configuration in which the flexible support members  124  are positioned within the matrix  122  material of the leaflets  104  and  106 . Although the cover  108  is illustrated as having the flexible support members  124  disposed substantially in the center of a cross section of the matrix  122 , it is understood that the flexible support members  124  can be disposed at a number of locations within the cover  108 . 
     In addition, different combinations of materials (discussed herein) can be used for one or more of the flexible support members  124  and/or the matrix  122  material. For example, the flexible support members  124  of the same structure and chemistry or different. structures and chemistries can be overlaid on top of one another to and combined with the matrix  122  material to fabricate a cover  108  having the desired mechanical strength and physical properties. In an additional embodiment, the cover  108  forming the leaflets  104  and  106  can have a configuration in which the matrix  122  can be formed of a first material and the flexible support members  124  can be formed of a second material different than the first material. For example, the leaflets  104  and  106  can include a top layer of the matrix  122  of the first material and a bottom layer of the matrix  122  of first material coupled to the top layer of the first material. The flexible support members  124  of the leaflets  104  and  106  can then be positioned to lie between the top and bottom layers of the first material. The matrix  122  can be integrated with the flexible support members  124  in such a way that the material of the matrix  122  penetrates through openings between the flexible support members  124  to interlock the matrix  122  and the flexible support members  124 . Surfaces of adjacent layers of the matrix  122  material can also interlock with one another, regardless of whether the layers of the matrix  122  are separated by a layer of the flexible support members  124  or whether they are made from the same or different materials. 
     In an additional embodiment, the flexible support members  124  can include a number of forms that contribute to both the mechanical and handling properties of the cover  108 . Examples of such forms for the flexible support members  124  include, but are not limited to, those selected from the group consisting of weaves, braids, meshes, knits, warped knitted (i.e., lace-like), matted, coils (continuous helically wound coils or individually positioned coils), rings, ribbons (individual or continuous), and non-woven structures including electrostatically spun fibers or fiber compositions of polymers, polymers and other materials such as various copolymers. 
     In addition, mechanical properties of the cover  108  can be altered by changing the density, form, and/or texture of the flexible support members  124  in one or more locations of the cover  108 . Examples of suitable structures used to create the flexible support members  124  can include, for example, monofilaments, yarns, threads, braids, or bundles of fibers. 
     Regardless of its configuration, the composite structure of the cover  108  should possess a burst strength adequate to withstand pressures imposed by blood moving in the circulation system. In addition, the cover  108  can be sufficiently thin and pliable so as to permit radially-collapsing of the leaflets  104  and  106  portion of the valve  100  to allow the valve  100  to provide the reversibly sealable opening  120  and for delivery by catheter to a location within a body lumen. As discussed herein, different portions of the matrix  122  and/or the flexible support members  124  may be made from different materials. Adequate strength and physical properties are developed in the cover  108  through the selection of materials used to form the matrix  122  and the flexible support members  124 , and the manufacturing process used to join them. 
     By way of example, both the matrix  122  and the flexible support members  124  can be formed of a number of materials. For example, the matrix  122  and/or the flexible support members  124  can be formed of, by way of illustration and not by limitation, thermoplastic and thenno-set polymers. Examples of these polymers include polyolefins such as polyethylene and polypropylene, polyesters such as Dacron, polyethylene terephthalate and polybutylene terephthalate, vinyl halide polymers such as polyvinyl chloride (PVC), polyvinylacetate such as ethyl vinyl acetate (EVA), polyurethanes, polytnethylmethacrylate, pellethane, polyamides such as nylon 4, nylon 6, nylon 66, nylon 610, nylon 11, nylon 12 and polycaprolactam, polyaramids (e.g., KEVLAR), polystyrene-polyisobutylene-polystyrene (SIBS), segmented poly(carbonate-urethane), Rayon, fluoropolymers such as polytetrafluoroethylene (PTFE or TFE) or expanded polytetrafluoroethylene (ePTFE), ethylene-chlorofluoroethylene (ECTFE), fluorinated ethylene propylene (FEP), polychlorotrifluoroethylene (PCTFE), polyvinylfluoride (PVF), or poly vinylidenefluoride (PVDF), natural biopolymers such as cellulose, chitin, keratin, silk, and collagen, explanted veins, decellularized basement membrane materials, submucosa materials such as small intestine submucosa (SIS) or umbilical vein, or other naturally occurring extracellular matrix (ECM), and other autologous or allogeneic biological materials either treated by crosslinking or not, and mixtures and copolymers thereof. SIS and ECM materials can be autologous, allogeneic or xenograft material derived from mammals, including source, such as human, cattle, sheep, and porcine. As will be appreciated, blends or mixtures of two or more of the materials provided herein are possible. For example, SIBS can be blended with one or more basement membrane materials. 
     Each of the polymers noted herein may be used in conjunction with radioopaque filler materials such as barium sulfate, bismuth trioxide, bismuth carbonate, powdered tungsten, powdered tantalum, or the like so that the location of the matrix  122  and/or the flexible support members  124  may be radiographically visualized within the human body. 
     In another embodiment of the present invention, the polymers and blends that are used to form the composite can be used as a drug delivery matrix. To form this matrix, the polymer can be mixed with a therapeutic agent or the agent can be applied to the surface or otherwise delivered from the material. The variety of different therapeutic agents that can be used in conjunction with the polymers of the present invention is vast. In general, therapeutic agents which may be administered via the pharmaceutical compositions of the invention include, without limitation: antiinfectives such as antibiotics and antiviral agents; analgesics and analgesic combinations; anti-inflammatory agents; hormones such as steroids; and naturally derived or genetically engineered proteins, polysaccharides, glycoproteins, or lipoproteins, anti-thrombotic agents, anti Pt agents, anti-immunogenic agents, anti-mitotic agents, anti proliferative agents, and angiogenic agents. Matrix formulations may be formulated by mixing one or more therapeutic agents with the polymer. The therapeutic agent may be present as a liquid, a finely divided solid, or any other appropriate physical form. Typically, but optionally, the matrix will include one or more additives, such as diluents, carriers, excipients, stabilizers or the like. Additionally, radioopaque markers may be added to the composite to allow imaging of the composite after implantation. 
     In an additional embodiment, the flexible support members  124  can be formed of ceramics, and/or metals. Suitable ceramics for the flexible support members  124  include those formed from basalt (solidified volcanic lava), and sold under the trade identifier “Sudaglass.” In one embodiment, the basalt can be mechanically crushed to provide the basalt in a fibrous form having a predetermined size of 9 to 17 microns in length. The basalt in the fibrous form can be blended with one or more of the polymers noted herein (e.g., SIBS, or polyolefins) so as to distribute the basalt in the fibrous form through the polymer matrix. In one embodiment, the basalt polymer composite can include 0.1 percent (wt.) basalt in the fibrous form. As will be appreciated, other weight percentage of basalt in the fibrous form relative polymer are possible. 
     The flexible support members  124  can also be formed of other nanostructures, such as carbon nanotubules. For example, carbon nano-tubules can be blended with one or more of the polymers noted herein (e.g., SIBS) so as to distribute the carbon nano-tubules through the polymer matrix. In one embodiment, the carbon nano-tubule polymer composite can include from 0.1 percent to 20 percent (wt.) carbon nano-tubules. As will be appreciated, other weight percentage of carbon nano-tubules relative polymer are possible. 
     The flexible support members  124  can also be formed of metals and/or metal alloys. For example, suitable metals and/or metal alloys for the flexible support members  124  include, but are not limited to, medical grade stainless steels (304, 306, 308, 316L, 318, etc.), gold, platinum, platinum alloys, palladium, rhodium, tungsten, tungsten alloys, cobalt chrome, titanium and titanium alloys, and other metal alloys such as those composed of titanium/nickel and sold under the trade identifier “Nitinol.” 
     Heat treatment of the Nitinol alloy may also be desirable. An example of such a heat treatment includes, but is not limited to, placing the Nitinol in its desired shape onto a mandrel. The Nitinol is then heated to a temperature of 650.degree.-750.degree. F. for a predetermined time (e.g., two (2) to five (5) minutes), possibly (but not necessarily) annealing the constituent Nitinol. After heat treatment, the flexible support members  124  retain their shape and the Nitinol alloy retains its super-elastic properties. 
     The support members  124  can also include a variety of cross-sectional configurations. For example, the support members  124  can have one or more of a round (e.g., circular, oval, and/or elliptical), “ribbon” configuration with rectangular geometries with an aspect ratio of at least 0.5 (thickness/width) having perpendicular sides, one or more convex sides, or one or more concave sides; semi-circular; triangular; tubular; I-shaped; T-shaped; and trapezoidal. Theses embodiment, however, are not limited to the present examples as other cross-sectional geometries are also possible. With respect to “braid,” the term can include tubular constructions in which the flexible support members  124  making up the construction are woven radially in an in-and-out fashion as they cross to form a tubular member defining a single lumen. The braid can also be constructed of flexible support members  124  of different widths. Changes in the braid can allow for pocket formation and the shape of the leaflets  104  and  106 , as discussed herein. Such pocket formation can allow the valve leaflet, in one embodiment, to not assume an absolutely planar or cylindrical shape but instead form a pocket or cupped depression that is more efficient at forming a seal between the two leaflets. This rounded shape adjacent the sinus region of the valve cusp can help allow the valve cusp to be rinsed by blood as the leaflet closes. 
       FIGS. 2A-2D  illustrate embodiments for a variety of configurations for the cover  208 . The embodiments illustrated in  FIGS. 2A-2D  are segment views (i.e., partial views) used to provide a non-limiting illustration of different configurations of the matrix  222  and the flexible support members  224  used in the cover  208 . For example,  FIG. 2A  illustrates an embodiment in which the matrix  122  includes a first layer  201  and a second layer  203  of material positioned around the flexible support members  224 . As illustrated in  FIG. 2A , the flexible support members  224  have a knit configuration. 
     In an additional embodiment,  FIG. 2B  illustrates an embodiment in which the matrix  222  includes the first layer  201  and the second layer  203  of material positioned around a first course  205  of the flexible support members  224 . The embodiment illustrated in  FIG. 2B  further includes a second course  207  of the flexible support members  224  positioned between the second layer  203  and a third layer  209  of the matrix  222 . As illustrated, the first course  205  and the second course  207  of the flexible support members  224  in  FIG. 2 b    have a woven configuration. As will be appreciated, different configurations of the flexible support members  224  (e.g., one flexible support member course having a knit configuration and one flexible support member course having a coil configuration) could be combined in the cover  204 . 
       FIG. 2C  illustrates another embodiment of the cover  208  that includes the matrix  222  surrounding the flexible support members  224  in a continuous helically wound coil configuration. As will be appreciated, the layers of the matrix  122  material can have all, some or none of the layers of the same or chemical composition. Similarly, the flexible support members  224  can have same or different configuration and/or chemical composition. In addition, mechanical properties of the cover  208  can be altered by changing the density, form, and/or texture of the flexible support members  224 . 
       FIG. 2D  illustrates another embodiment of the cover  208  that includes the matrix  222  that includes a distribution of the flexible support members  224 . In one embodiment, the distribution of the flexible support members  224  can include a distribution of the nanostructures (e.g., basalt, and/or carbon nanotubules), as discussed herein. As will be appreciated, the layers of the matrix  122  material can have all, some or none of the layers of the same or chemical composition. Similarly, the flexible support members  224  can have same or different configuration and/or chemical composition. In addition, mechanical properties of the cover  208  can be altered by changing the density, form, and/or texture of the flexible support members  224 . 
     Referring again to  FIGS. 1A-1D , the fibers used in the flexible support members  124  may be made using a variety of processes that provide fibers with the desired properties (such as modulus, tensile strength, elongation etc.). Those skilled in the art of fiber processing are well versed in the art of extrusion, paste extrusion and stretching, solution spinning, electrostatic spinning, along with other fiber processing techniques, which may be used to provide polymer based fibers. These fibers may be oriented or drawn using conventional process to provide the desired degree of modulus, strength, and elongation. Generally, a fiber orientation process is used to improve the properties of the reinforcing fibers. The fibers can be oriented using a variety of drawing technologies such as single, multiple or continuous drawing steps with or without heating zones and/or relaxation. Additionally, these fibers may be post treated with various annealing, scouring, coating or surface treatment steps. 
     As will be appreciated, the cover  108  can be formed in any number of ways. For example, the embodiments of the cover  108  can be made by injecting, pouring, casting, or otherwise placing the matrix  122  material (e.g., a polymer solution) into a mold set-up comprised of a mold and the flexible support members  124 . Alternatively, the embodiments of the cover  108  can be made by blending, or mixing, the matrix  122  material (e.g., a polymer) with flexible support members  124  (e.g., the carbon nano-tubules, or fibrous Basalt) before or during the injecting, pouring, or casting process into the mold. 
     The general processing steps include the selection of the materials from which the matrix  122  and the flexible support members  124  are made. In one embodiment, the cover  108  can generally be formed by use of compression molding in the mold set-up under a dry inert environment (for example, under nitrogen and/or argon) or under vacuum, at high enough temperatures, pressures, and long enough residence times (with proper cooling) to consolidate the composite. Alternately, the cover  108  composite can be formed by use of an autoclave, under a dry inert environment or under vacuum, at high enough temperatures and long enough residence times to consolidate the composite. Proper consolidation condition should provide a composite with no voids therein. 
     The flexible support members  124  are generally ceramic and/or polymeric (e.g., semi-crystalline polymers) while the matrix  122  materials are generally either amorphous or semi-crystalline polymers. In conventional composites, such as glass or carbon reinforced composites, the flexible support members  124  are not affected by consolidation temperature of the matrix  122 . In addition, some or all of the fibers of the flexible support members  124  can be restrained during the consolidation process. The flexible support members  124  can be restrained during the heat treatment or the consolidation in a variety of ways, including, but not limited to, mechanical clamps or rack systems. This allows a reduction or a minimization in relaxation of fiber orientation. Additionally restraining the flexible support members  124  will control or avoid shrinkage of the flexible support members  124  during heat treatment and/or consolidation. 
     In an alternative embodiment, the matrix  122  material can be extruded or formed into a tubing of appropriate size and thickness. The material of the matrix  122  can then be cross-linked to raise the melt temperature of the resulting tube. The tube can then inflated and stretched to give the included polymer a specific molecular orientation. The tube of the matrix  122  material can then be placed over the combination of an inner layer of the matrix  122  material and the flexible support members  124  and the material of the matrix  122  heat-shrunk around the flexible support members  124 . Alternatively, the flexible support members  124  can be dipped into molten material of the matrix  122  to form the cover  108 . In yet another embodiment, suitable adhesive for the selected materials can be used to bond the matrix  122  material to additional layers of the matrix  122  material and to layers of the flexible support members  124 . In an additional embodiment, the matrix  122  can be co-processed with the flexible support members  124  (e.g., nanostructures or fibrous basalt) so as to distribute the flexible support members  124  through the matrix  122 . 
     In addition to the cover  108 , the frame  102  too can be formed from a wide variety of materials and in a wide variety of configurations. Generally, frame  102  can have a unitary structure with an open frame configuration. For example, the open frame configuration can include frame members  126  that define openings  128  across the frame  102  through which valve leaflets  104  and  106  formed by the cover  108  can radially-collapse and radially-expand, as will be described herein. 
     In addition, the first end  112  and the second end  114  each include a plurality of end portions  130  that lay on a common plane. The plurality of end portions  130 , however, need not all lay on the common plane. In other words, it is possible that one or more of the end portions  130  of the frame  102  lay above and/or below the common plane. 
     While the frames illustrated herein, for example frame  102 , are shown as having a circular configuration, other configurations are also possible. For example, the frame  102  could have an elliptical configuration. As such, the present invention should not be limited to the illustration of the frames, such as frame  102 , provided herein. 
     As illustrated in  FIGS. 1A-1D , the frame  102  can further include a first leaflet connection region  132  and a second leaflet connection region  134  adjacent the second end  114  of the frame  102 . In the present example, the cover  108  can be coupled, as described more fully herein, to at least the first leaflet connection region  132  and the second leaflet connection region  134 . The cover  108  so coupled can then move (e.g., pivot) relative the first leaflet connection region  132  and the second leaflet connection region  134  between an open valve configuration (illustrated in  FIGS. 1A . and  1 C) and a closed valve configuration (illustrated in  FIGS. 1B and 1D ). As illustrated in the closed valve configuration ( FIGS. 1B and 1D ), the open frame configuration of frame  102  allows cover  108  to move through the openings  128  in creating the reversible sealable opening  120  of the valve  100 . 
     As illustrated in  FIGS. 1A-1D , the first leaflet connection region  132  and the second leaflet connection region  134  can be positioned opposite each other along a common axis. In addition, the first leaflet connection region  132  and the second leaflet connection region  134  can be radially symmetric around a longitudinal central axis  138  of the frame  102 . As illustrated, the first leaflet connection region  132  and the second leaflet connection region  134  can be positioned approximately one hundred eighty (180) degrees relative each other around the longitudinal central axis  138  of the frame  102 . As will be appreciated, the first leaflet connection region  132  and the second leaflet connection region  134  need not necessarily display an equally spaced symmetrical relationship as described above in order to practice the embodiments of the present invention. For example, the radial relationship can have the first leaflet connection region  132  and the second leaflet connection region  134  positioned at values greater than one hundred eighty (180) degrees and less than one hundred eighty (180) degrees relative each other around the longitudinal central axis  138  of the frame  102 . 
     The frame  102  can have similar and/or different cross-sectional geometries along its length. The similarity and/or the differences in the cross-sectional geometries can be based on one or more desired functions to be elicited from each portion of the frame  102 . For example, the frame  102  can have a similar cross-sectional geometry along its length. Examples of cross-sectional geometries include, but are not limited to, round (e.g., circular, oval, and/or elliptical), rectangular geometries having perpendicular sides, one or more convex sides, or one or more concave sides; semi-circular; triangular; tubular; I-shaped; T-shaped; and trapezoidal. These embodiments, however, are not limited to the present examples as other cross-sectional geometries are also possible. As such, the present invention should not be limited to the frames provided in the illustration herein. 
     The valve  100  can further include a radial support member  140 . The radial support member  140  can include a number of different configurations, as will be described herein. For example, in the embodiment illustrated in  FIGS. 1A-1D , the radial support member  140  couples the first leaflet connection region  132  and the second leaflet connection region  134 . In addition to coupling the connection regions  132  and  134 , the radial support member  140  can also serve to stabilize the relative positions of the connection regions  132  and  134  (e.g., limit relative fluctuations of the connection regions  132  and  134 ). 
     In the present embodiment, the radial support member  140  can be in the form of a tubular ring  142  that joins to the first leaflet connection region  132  and the second leaflet connection region  134 . The valve  100  can further include a second tubular ring  144  located at the first end  112  of the frame  102 . The tubular rings  142  and  144  can also move radially as the valve  100  radially collapses and expands. As will be appreciated, the valve  100  could further include additional tubular rings located at one or more positions along the frame  102 . In an alternative embodiment, the radial support member can be provided to the frame  102  of the valve  100  due in part to dimensional relationships imparted to the frame  102  that are more fully described in co-pending U.S. patent application Ser. No. 11/150,331 to Hill et al. entitled “Venous Valve Frame, System, and Method” (BSCI Docket #04-0081US), which is hereby incorporated by reference in its entirety. 
     As illustrated, the cover  108  can be positioned over one or both of the radial support member  140  and the second tubular ring  144 . As will be appreciated, the cover  108  need not extend to cover one or both of the radial support member  140  and the second tubular ring  144 . 
     The compressible nature of the valve  100  can accommodate changes in body lumen size (e.g., diameter of the body lumen) by flexing to expand and/or contract to change the diameter of the frame  102 . In one embodiment, the corner portions of the tubular rings  142  and  144 , and the first leaflet connection region  132  and the second leaflet connection region  134  can act as springs to allow the valve  100  to resiliently radially collapse and expand. The frame  102  can also provide sufficient contact and expansion force with the surface of a body lumen wall to encourage fixation of the valve  100  and to prevent retrograde flow within the body lumen around the edges of the frame  102  and the surface of a lumen when combined with a closed state of the valve leaflets (described in more detail below) attached thereto. Anchoring elements (e.g., barbs) can also be included with valve  100 , as will be discussed herein. 
       FIGS. 3A and 3B  provide an example of the valve  300  in a collapsed state ( FIG. 3A ) and in an expanded state ( FIG. 3B ). As shown in  FIGS. 3A and 3B , the valve  300  can travel between the collapsed and the expanded state along a radial travel path  346  (as shown in  FIG. 3B ), where there can be a change in a cross sectional area  348  of lumen  310 . For example, the frame  302  can travel along the radial travel path  346  so as to change a width  350  of lumen  310 . This can allow the valve  300  to react appropriately to the distension and contraction of a body lumen in which the valve  300  is placed.  FIGS. 3A and 3B  also provide an illustration of the valve  300  having a different configuration for the radial support members. 
     The embodiments of the frame discussed herein can also be constructed of one or more of a number of materials and in a variety of configurations. Generally, the frame embodiments can have a unitary structure with an open frame configuration. The frame can also be self-expanding. Examples of self-expanding frames include those formed from temperature-sensitive memory alloy (e.g., Nitinol) which changes shape at a designated temperature or temperature range. Alternatively, the self-expanding frames can include those having a spring-bias. In addition, the frame  102  can have a configuration that allows the frame embodiments be radially expandable through the use of a balloon catheter. 
     The embodiments of the frame, such as frame  102  in  FIG. 1 , can also be formed from one or more contiguous frame members. For example, the frame member of frame embodiments can be a single contiguous member. The single contiguous member can be bent around an elongate tubular mandrel to form the frame. The free ends of the single contiguous member can then be welded, fused, crimped, or otherwise joined together to form the frame. In an additional embodiment, the frame member of frame can be derived (e.g., laser cut, water cut) from a single tubular segment. In an alternative embodiment, methods of joining the frame member to create the elastic region include, but are not limited to, welding, gluing, and fusing the frame member. The frame can be heat set by a method as is typically known for the material which forms the frame. 
     The frame embodiments can be formed from a number of materials. For example, the frame can be formed from a biocompatible metal, metal alloy, polymeric material, or combination thereof. As discussed herein, the frame can be self-expanding or balloon expandable. In addition, the frame can be configured so as to have the ability to move radially between the collapsed state and the expanded state. To accomplish this, the material used to form the frame should exhibit a low elastic modulus and a high yield stress for large elastic strains that can recover from elastic deformations. Examples of suitable materials include, but are not limited to, medical grade stainless steel (e.g., 316L), titanium, tantalum, platinum alloys, niobium alloys, cobalt alloys, alginate, or combinations thereof. Additional frame embodiments may be formed from a shape-memory material, such as shape memory plastics, polymers, and thermoplastic materials which are inert in the body. Shaped memory alloys having superelastic properties generally made from ratios of nickel and titanium, commonly known as Nitinol, are also possible materials. Other materials are also possible. 
     The lumen  110  can include a number of sizes. For example, the size of the lumen can be determined based upon the type of body lumen and the body lumen size in which the valve is to be placed. In an additional example, there can also be a minimum value for the width for the frame that ensures that the frame will have an appropriate expansion force against the inner wall of the body lumen in which the valve is being placed. For example, the diameter can range from 4 mm to 20 mm. Other diameter values are also possible. 
     In one embodiment, the frame can further include one or more anchoring elements. For example, the one or more anchoring elements can include, but are not limited to, one or more barbs  152  projecting from the frame  102 . The valve can further include one or more radiopaque markers (e.g., tabs, sleeves, welds). For example, one or more portions of the frame can be formed from a radiopaque material. Radiopaque markers can be attached to and/or coated onto one or more locations along the frame. Examples of radiopaque material include, but are not limited to, gold, tantalum, and platinum. The position of the one or more radiopaque markers can be selected so as to provide information on the position, location and orientation of the valve during its implantation. 
     As discussed herein, valve  100  further includes cover  108  having surfaces defining the reversibly sealable opening  120  for unidirectional flow of a liquid through the lumen  110 . For the embodiment illustrated in  FIGS. 1A-1D , the cover  108  extends over at least a portion of the frame  102  to the first leaflet connection region  132  and the second leaflet connection region  134 . The cover  108  extends between the first leaflet connection region  132  and the second leaflet connection region  134  to provide the first valve leaflet  104  and the second valve leaflet  106  of the valve leaflets. The first valve leaflet  104  and the second valve leaflet  106  include surfaces defining the reversibly sealable opening  120  extending between the first leaflet connection region  132  and the second leaflet connection region  134  for unidirectional flow of a liquid through the valve  100 . 
     As illustrated, the valve leaflets  104  and  106  include a region  154  of the cover  108  that can move relative the frame  102 . The region  154  of the cover  108  can be unbound (i.e., unsupported) by the frame  102  and extends between the first leaflet connection region  132  and the second leaflet connection region  134  of the valve  100 . This configuration permits the reversibly sealable opening  120  to open and close in response to the fluid pressure differential across the valve leaflets  104  and  106 . 
     For example, under antegrade fluid flow (i.e., positive fluid pressure) from the first end  112  towards the second end  114  of the valve  100 , the valve leaflets  104  and  106  can expand toward the inner surface  118  of the frame  102  to create an opening through which fluid is permitted to move. In one example, the valve leaflets  104  and  106  each expand to define a semi-tubular structure when fluid opens the reversibly sealable opening  120 . An example of the open configuration for the valve is shown in  FIGS. 1A and 1C . 
     Under a retrograde fluid flow from the second end  114  towards the first end  112 , the valve leaflets can move relative the inner surface  118  as the valve leaflets begin to close. In one example, a pocket exists between the frame  102  and each of the valve leaflets. The pocket allows fluid from the retrograde flow to develop a lower pressure on a first major face  155  of the valve leaflets than on the second major face  157  of the valve leaflets causing the valve leaflets to begin to close. As fluid pressure develops on the pocket regions formed on the second major face  157 , the valve leaflets collapse, closing the reversibly sealable opening  120 , thereby restricting retrograde fluid flow through the valve  100 . In the closed configuration, the valve leaflets can each have a concave structure when fluid closes the reversibly sealable opening  120 . In one embodiment, the concave structure can be imparted to the valve leaflets due to the configuration of the flexible support members  124  and/or the matrix  122 . An example of the closed configuration for the valve is shown in  FIGS. 1B and 1D . 
     Valve  100  provides an embodiment in which the surfaces defining the reversibly sealable opening  120  provide a bi-leaflet configuration (i.e., a bicuspid valve) for valve  100 . Although the embodiments in  FIGS. 1A-1D  illustrate and describe a bi-leaflet configuration for the valve of the present invention, designs employing a different number of valve leaflets (e.g., trileaflet valve) are possible. For example, additional connection points (e.g., three or more) could be used to provide additional valve leaflets (e.g., a tri-leaflet valve). 
     The valve leaflets can have a variety of sizes and shapes. For example, each of the valve leaflets can have a similar size and shape. Alternatively, each of the valve leaflets need not have a similar size and shape (i.e., the valve leaflets can have a different size and shape with respect to each other). In addition, each of the valve leaflets include sufficient excess material spanning frame  102  such that fluid pressure (e.g., antegrade flow) acting on the region  154  of the valve leaflets forces the valve  100  into an open configuration ( FIGS. 1A and 1C ). The valve leaflets further include arcuate edges  156  that are positioned adjacent each other along a substantially catenary curve between the leaflet connection regions  132  and  134  in the closed configuration ( FIGS. 1B and 1D ) of valve  100 . Similarly, arcuate edges  156  can define opening  120  when the valve  100  is in the open configuration ( FIGS. 1A and 1C ). 
     In an additional embodiment, in the open configuration the portion of the cover  108  forming the valve leaflets  104  and  106  provides sufficient excess material spanning between the leaflet connection regions  132  and  134  to allow the leaflets to take on a semi-tubular structure, as shown in  FIG. 1A , when fluid pressure opens the valve  100 . In an additional embodiment, arcuate edges  156  of valve  100  can open to approximately the full inner diameter of a body lumen. Alternatively, the arcuate edges  156  of valve  100  can open to approximately a diameter that is less than the full inner of a body lumen.  FIGS. 1A and 1C  provide an illustration of this latter embodiment, where a space  163  can be present between the second major face  157  of the valve leaflets and the inner surface  118  of the frame  102 . 
     Each of the regions  154  of the valve leaflets can further include a concave structure that allows the valve leaflets to better collect retrograde fluid flow to urge the valve leaflets towards the closed configuration. For example, as retrograde flow begins, the valve leaflets respond by moving towards the center of valve  100 . As the valve leaflets approach the center of the leaflets make sufficient contact to effectively close valve  100  and restrict retrograde fluid flow. 
     As discussed herein, the cover  108  can be located over at least the outer surface  116  and the inner surface  118  of the frame  102  to form the valve leaflets  104  and  106  as described herein. Alternatively, the cover  108  can be located over the inner surface  118  of the frame  102 , or the cover  108  can be located over the outer surface  116  of the frame  102  to form the valve leaflets  104  and  106  as described herein. Numerous techniques may be employed to laminate or bond cover  108  on the outer surface  116  and/or the inner surface  118  of the frame  102 , including heat setting, adhesive welding, application of uniform force and other bonding techniques. Additionally, the cover  108  may be folded over the first end  112  of the frame  102  to provide the cover  108  on both the outer surface  116  and the inner surface  118 . Cover  108  can also be joined to itself and/or the members  126  according to the methods described in U.S. Patent Application Publication US 2002/0178570 to Sogard et al., which is hereby incorporated by reference in its entirety. 
     The cover  108  can also be coupled to the connection regions so as to form the valve leaflets, as discussed herein. In one embodiment, the cover  108  can be in the form of a sheet or a sleeve of material, as discussed herein, which can be connected to the frame  102 . Other forms, including intermediate forms, of the cover  108  are also possible. 
     The cover  108  can be coupled to the frame  102 , including the connection regions  132  and  134 , in a variety of ways so as to provide the various embodiments of the valve of the present invention. For example, a variety of fasteners can be used to couple the cover  108  to the frame  102  so as to form the valve  100 . Suitable fasteners can include, but are not limited to, biocompatible staples, glues, sutures or combinations thereof. In an additional embodiment, the cover  108  can be coupled to the frame  102  through the use of heat sealing, solvent bonding, adhesive bonding, or welding cover  108  to either a portion of the cover  108  (i.e., itself) and/or the frame  102 . 
     The cover  108 , including the valve leaflets  104  and  106 , may also be treated and/or coated with any number of surface or material treatments. For example, suitable bioactive agents which may be incorporated with or utilized together with embodiments of the present invention may include silver antimicrobial agents, metallic antimicrobial materials, growth factors, cellular migration agents, cellular proliferation agents, anti-coagulant substances, stenosis inhibitors, thrombo-resistant agents, antibiotic agents, anti-tumor agents, anti-proliferative agents, growth hormones, antiviral agents, anti-angiogenic agents, angiogenic agents, cholesterol-lowering agents, vasodilating agents, agents that interfere with endogenous vasoactive mechanisms, hormones, their homologs, derivatives, fragments, pharmaceutical salts and combinations thereof. 
     In the various embodiments of the present invention, the most useful bioactive agents can include those that modulate thrombosis, those that encourage cellular ingrowth, throughgrowth, and endothelialization, those that resist infection, and those that reduce calcification. For example, the cover  108  can be treated with one or more biologically active compounds and/or materials that may promote and/or inhibit endothelial, smooth muscle, fibroblast, and/or other cellular growth onto or into the cover  108 , including the valve leaflets. Similarly, the cover  108  may be seeded and covered with cultured tissue cells (e.g., endothelial cells) derived from a either a donor or the host patient which are attached to the valve leaflets. The cultured tissue cells may be initially positioned to extend either partially or fully over the valve leaflets. 
     Cover  108 , in addition to forming valve leaflets  104  and  106 , can also be capable of inhibiting thrombus formation, as discussed herein. Additionally, cover  108  may either prevent or facilitate tissue ingrowth therethrough, as the particular application for the valve  100  may dictate. For example, cover  108  on the outer surface  116  may be formed from a porous material to facilitate tissue ingrowth therethrough, while cover  108  on the inner surface  118  may be formed from a material or a treated material which inhibits tissue ingrowth. 
     Cells can be associated with the present invention. For example, cells that have been genetically engineered to deliver bioactive proteins, such as the above mentioned growth factors or antibodies, to the implant site can be associated with the present invention. Cells can be of human origin (autologous or allogenic) or from an animal source (xenogenic). Cells can be pre-treated with medication or pre-processed such as by sorting or encapsulation. The delivery media can be formulated as needed to maintain cell function and viability. 
     Thrombo-resistant agents associated with the present invention can include, but are not limited to, the following: heparin, heparin sulfate, hirudin, hyaluronic acid, chondroitin sulfate, dermatin sulfate, keratin sulfate, PPack (detropyenylalanine praline arginine chloromethylketone), lytic agents, including urokinase and streptokinase, their homologs, analogs, fragments, derivatives and pharmaceutical salts thereof. 
     Anti-coagulants can include, but are not limited to, the following: D-Phe-Pro-Arg chloromethyl ketone, an ROD peptide-containing compound, heparain, antithrombin compounds, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, aspirin, prostaglandin inhibitors, platelet inhibitors, tick antiplatelet peptides and combinations thereof. 
     Antibiotic agents can include, but are not limited to, the following agents: penicillins, cephalosportins, vancomycins, aminoglycosides, quinolonges, polymyxins, erythromycins, tetracyclines, chloraphenieols, clindamycins, lincomycins, sulfonamides, their homologs, analogs, derivatives, pharmaceutical salts and combinations thereof. 
     Anti-proliferative agents for use in the present invention can include, but are not limited to, the following: paclitaxel, sirolimus, everolimus, or monoclonal antibodies capable of blocking smooth muscle cell proliferation, related compounds, derivatives, and combinations thereof. 
     Vascular cell growth inhibitors can include, but are not limited to, the following: growth factor inhibitors, growth factor receptor antagonists, transcriptional repressors, translational repressors, replication inhibitors, inhibitory antibodies, antibodies directed against growth factors, bifunctional molecules consisting of a growth factor and a cytotoxin, bifunctional molecules consisting of a an antibody and a cytotoxin. 
     Vascular cell growth promoters can include, but are not limited to, transcriptional activators and transcriptional promoters. And, anti-inflammatory agents can include, but are not limited to, the following: dexametbasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazinemesalamne, and combinations thereof. 
       FIG. 4  illustrates one embodiment of a system  470 . System  470  includes valve  400 , as described herein, reversibly joined to catheter  472 . The catheter  472  includes an elongate body  474  having a proximal end  476  and a distal end  478 , where valve  400  can be located between the proximal end  476  and distal end  478 . The catheter  472  can further include a lumen  480  longitudinally extending to the distal end  478 . In one embodiment, lumen  480  extends between proximal end  476  and distal end  478  of catheter  472 . The catheter  472  can further include a guidewire lumen  482  that extends within the elongate body  474 , where the guidewire lumen  482  can receive a guidewire for positioning the catheter  472  and the valve  400  within a body lumen (e.g., a vein of a patient). 
     The system  470  can further include a deployment shaft  484  positioned within lumen  480 , and a sheath  486  positioned adjacent the distal end  478 . In one embodiment, the valve  400  can be positioned at least partially within the sheath  486  and adjacent the deployment shaft  484 . The deployment shaft  484  can be moved within the lumen  478  to deploy valve  400 . For example, deployment shaft  484  can be used to push valve  400  from sheath  486  in deploying valve  400 . 
       FIG. 5  illustrates an additional embodiment of the system  570 . The catheter  572  includes elongate body  574 , lumen  580 , a retraction system  588  and a retractable sheath  590 . The retractable sheath  590  can be positioned over at least a portion of the elongate body  574 , where the retractable sheath  590  can move longitudinally along the elongate body  574 . The valve  500  can be positioned at least partially within the retractable sheath  590 , where the retractable sheath  590  moves along the elongate body  574  to deploy the valve  500 . In one embodiment, retraction system  588  includes one or more wires  592  coupled to the retractable sheath  590 , where the wires are positioned at least partially within and extend through lumen  580  in the elongate body  574 . Wires of the retraction system  588  can then be used to retract the retractable sheath  590  in deploying valve  500 . 
       FIG. 6  illustrates an additional embodiment of the system  670 . The catheter  672  includes elongate body  674 , an inflatable balloon  694  positioned adjacent the distal end  678 , and a lumen  680  longitudinally extending in the elongate body  674  of the catheter  672  from the inflatable balloon  694  to the proximal end  676 . In the present example, the inflatable balloon  694  can be at least partially positioned within the lumen  606  of the valve  600 . The inflatable balloon  694  can be inflated through the lumen  680  to deploy the valve  600 . 
     The embodiments of the present invention further include methods for forming the valve of the present invention, as discussed herein. For example, the method of forming the valve can include forming the frame having the leaflet connection regions, as described. The method can include providing the radial support member, or members, on the frame for the leaflet connection regions. As discussed herein, the radial support member can include the tubular rings adjacent the leaflet connection regions. The method also includes providing the cover on the frame, where connecting the cover to the leaflet connection regions provides at least the first leaflet and the second leaflet of the valve having surfaces defining the reversibly sealable opening for unidirectional flow of a liquid through the valve. 
     In an additional example, the valve can be reversibly joined to the catheter, which can include a process of altering the shape of the valve from a first shape, for example an expanded state, to the compressed state, as described herein. For example, the valve can be reversibly joined with the catheter by positioning valve in the compressed state at least partially within the sheath of the catheter. In one embodiment, positioning the valve at least partially within the sheath of the catheter includes positioning the valve in the compressed state adjacent the deployment shaft of the catheter. In an another embodiment, the sheath of the catheter functions as a retractable sheath, where the valve in the compressed state can be reversibly joined with the catheter by positioning the valve at least partially within the reversible sheath of the catheter. In a further embodiment, the catheter can include an inflatable balloon, where the balloon can be positioned at least partially within the lumen of the valve, for example, in its compressed state. 
     The embodiments of the valve described herein may be used to replace, supplement, or augment valve structures within one or more lumens of the body. For example, embodiments of the present invention may be used to replace an incompetent venous valve and help to decrease backflow of blood in the venous system of the legs. 
     In one embodiment, the method of replacing, supplementing, and/or augmenting a valve structure can include positioning at least part of the catheter including the valve at a predetermined location within the lumen of a body. For example, the predetermined location can include a position within a body lumen of a venous system of a patient, such as a vein of a leg. 
     In one embodiment, positioning the catheter that includes the valve within the body lumen of a venous system includes introducing the catheter into the venous system of the patient using minimally invasive percutaneous, transluminal catheter based delivery system, as is known in the art. For example, a guidewire can be positioned within a body lumen of a patient that includes the predetermined location. The catheter, including valve, as described herein, can be positioned over the guidewire and the catheter advanced so as to position the valve at or adjacent the predetermined location. In one embodiment, radiopaque markers on the catheter and/or the valve, as described herein, can be used to help locate and position the valve. 
     The valve can be deployed from the catheter at the predetermined location in a number of ways, as described herein. In one embodiment, valve of the present invention can be deployed and placed in a number of vascular locations. For example, valve can be deployed and placed within a major vein of a patient&#39;s leg. In one embodiment, major veins include, but are not limited to, those of the peripheral venous system. Examples of veins in the peripheral venous system include, but are not limited to, the superficial veins such as the short saphenous vein and the greater saphenous vein, and the veins of the deep venous system, such as the popliteal vein and the femoral vein. 
     As discussed herein, the valve can be deployed from the catheter in a number of ways. For example, the catheter can include the retractable sheath in which valve can be at least partially housed, as discussed herein. Valve can be deployed by retracting the retractable sheath of the catheter, where the valve self-expands to be positioned at the predetermined location. In an additional example, the catheter can include a deployment shaft and sheath in which valve can be at least partially housed adjacent the deployment shaft, as discussed herein. Valve can be deployed by moving the deployment shaft through the catheter to deploy valve from the sheath, where the valve self-expands to be positioned at the predetermined location. In an additional embodiment, the valve can be deployed through the use of an inflatable balloon. 
     Once implanted, the valve can provide sufficient contact and expansion force against the body lumen wall to prevent retrograde flow between the valve and the body lumen wall. For example, the valve can be selected to have a larger expansion diameter than the diameter of the inner wall of the body lumen. This can then allow valve to exert a force on the body lumen wall and accommodate changes in the body lumen diameter, while maintaining the proper placement of valve. As described herein, the valve can engage the lumen so as to reduce the volume of retrograde flow through and around valve. It is, however, understood that some leaking or fluid flow may occur between the valve and the body lumen and/or through valve leaflets. 
     In addition, the use of both the radial support member and/or the support frame region of the valve can provide a self centering aspect to valve within a body lumen. In one embodiment, the self centering aspect resulting from the radial support member and/or the support frame region may allow valve to maintain a substantially coaxial alignment with the body lumen (e.g., such as a vein) as valve leaflets deflect between the open and closed configurations so as to better seal the reversible opening when valve is closed. 
     While the present invention has been shown and described in detail above, it will be clear to the person skilled in the art that changes and modifications may be made without departing from the scope of the invention. As such, that which is set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined by the following claims, along with the full range of equivalents to which such claims are entitled. 
     In addition, one of ordinary skill in the art will appreciate upon reading and understanding this disclosure that other variations for the invention described herein can be included within the scope of the present invention. For example, the frame  102  and/or the cover  108  can be coated with a non-thrombogenic biocompatible material, as are known or will be known. 
     In the foregoing Detailed Description, various features are grouped together in several embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.