Patent Publication Number: US-2012035719-A1

Title: Prosthetic Heart Valves, Support Structures and Systems and Methods for Implanting the Same

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 11/469,771, filed Sep. 1, 2006, now abandoned, which is a continuation of U.S. application Ser. No. 11/425,361, filed Jun. 20, 2006, now abandoned, which is a continuation-in-part of U.S. application Ser. No. 11/066,126, filed Feb. 25, 2005, now pending, which is related to U.S. Application Ser. No. 60/548,731, filed Feb. 27, 2004, all of which are fully incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to medical devices and methods. More particularly, the present invention relates to prosthetic heart valves, structures for providing scaffolding of body lumens, and devices and methods for delivering and deploying these valves and structures. 
     BACKGROUND INFORMATION 
     Diseases and other disorders of the heart valve affect the proper flow of blood from the heart. Two categories of heart valve disease are stenosis and incompetence. Stenosis refers to a failure of the valve to open fully, due to stiffened valve tissue. Incompetence refers to valves that cause inefficient blood circulation by permitting backflow of blood in the heart. 
     Medication may be used to treat some heart valve disorders, but many cases require replacement of the native valve with a prosthetic heart valve. Prosthetic heart valves can be used to replace any of the native heart valves (aortic, mitral, tricuspid or pulmonary), although repair or replacement of the aortic or mitral valves is most common because they reside in the left side of the heart where pressures are the greatest. Two primary types of prosthetic heart valves are commonly used, mechanical heart valves and prosthetic tissue heart valves. 
     The caged ball design is one of the early mechanical heart valves. The caged ball design uses a small ball that is held in place by a welded metal cage. In the mid-1960s, another prosthetic valve was designed that used a tilting disc to better mimic the natural patterns of blood flow. The tilting-disc valves had a polymer disc held in place by two welded struts. The bileaflet valve was introduced in the late 1970s. It included two semicircular leaflets that pivot on hinges. The leaflets swing open completely, parallel to the direction of the blood flow. They do not close completely, which allows some backflow. 
     The main advantages of mechanical valves are their high durability. Mechanical heart valves are placed in young patients because they typically last for the lifetime of the patient. The main problem with all mechanical valves is the increased risk of blood clotting. 
     Prosthetic tissue valves include human tissue valves and animal tissue valves. Both types are often referred to as bioprosthetic valves. The design of bioprosthetic valves are closer to the design of the natural valve. Bioprosthetic valves do not require long-term anticoagulants, have better hemodynamics, do not cause damage to blood cells, and do not suffer from many of the structural problems experienced by the mechanical heart valves. 
     Human tissue valves include homografts, which are valves that are transplanted from another human being, and autografts, which are valves that are transplanted from one position to another within the same person. 
     Animal tissue valves are most often heart tissues recovered from animals. The recovered tissues are typically stiffened by a tanning solution, most often glutaraldehyde. The most commonly used animal tissues are porcine, bovine, and equine pericardial tissue. 
     The animal tissue valves are typically stented valves. Stentless valves are made by removing the entire aortic root and adjacent aorta as a block, usually from a pig. The coronary arteries are tied off, and the entire section is trimmed and then implanted into the patient. 
     A conventional heart valve replacement surgery involves accessing the heart in the patent&#39;s thoracic cavity through a longitudinal incision in the chest. For example, a median sternotomy requires cutting through the sternum and forcing the two opposing halves of the rib cage to be spread apart, allowing access to the thoracic cavity and heart within. The patient is then placed on cardiopulmonary bypass which involves stopping the heart to permit access to the internal chambers. Such open heart surgery is particularly invasive and involves a lengthy and difficult recovery period. 
     A less invasive approach to valve replacement is desired. The percutaneous implantation of a prosthetic valve is a preferred procedure because the operation is performed under local anesthesia, does not require cardiopulmonary bypass, and is less traumatic. Current attempts to provide such a device generally involve stent-like structures, which are very similar to those used in vascular stent procedures with the exception of being larger diameter as required for the aortic anatomy, as well as having leaflets attached to provide one way blood flow. These stent structures are radially contracted for delivery to the intended site, and then expanded/deployed to achieve a tubular structure in the annulus. The stent structure needs to provide two primary functions. First, the structure needs to provide adequate radial stiffness when in the expanded state. Radial stiffness is required to maintain the cylindrical shape of the structure, which assures the leaflets coapt properly. Proper leaflet coaption assures the edges of the leaflets mate properly, which is necessary for proper sealing without leaks. Radial stiffness also assures that there will be no paravalvular leakage, which is leaking between the valve and aorta interface, rather than through the leaflets. An additional need for radial stiffness is to provide sufficient interaction between the valve and native aortic wall that there will be no valve migration as the valve closes and holds full body blood pressure. This is a requirement that other vascular devices are not subjected to. The second primary function of the stent structure is the ability to be crimped to a reduced size for implantation. 
     Prior devices have utilized traditional stenting designs which are produced from tubing or wire wound structures. Although this type of design can provide for crimpability, it provides little radial stiffness. These devices are subject to “radial recoil” in that when the device is deployed, typically with balloon expansion, the final deployed diameter is smaller than the diameter the balloon and stent structure were expanded to. The recoil is due in part because of the stiffness mismatches between the device and the anatomical environment in which it is placed. These devices also commonly cause crushing, tearing, or other deformation to the valve leaflets during the contraction and expansion procedures. Other stenting designs have included spirally wound metallic sheets. This type of design provides high radial stiffness, yet crimping results in large material strains that can cause stress fractures and extremely large amounts of stored energy in the constrained state. Replacement heart valves are expected to survive for many years when implanted. A heart valve sees approximately 500,000,000 cycles over the course of 15 years. High stress states during crimping can reduce the fatigue life of the device. Still other devices have included tubing, wire wound structures, or spirally wound sheets formed of nitinol or other superelastic or shape memory material. These devices suffer from some of the same deficiencies as those described above. The scaffolding structures and prosthetic valves described herein address both attributes of high radial stiffness along with crimpability, and maximizing fatigue life. 
     SUMMARY 
     The present invention provides apparatus and methods for deploying support structures in body lumens. The methods and apparatus are particularly adapted for use in percutaneous aortic valve replacement. The methods and apparatus may also find use in the peripheral vasculature, the abdominal vasculature, and in other ducts such as the biliary duct, the fallopian tubes, and similar lumen structures within the body of a patient. Although particularly adapted for use in lumens found in the human body, the apparatus and methods may also find application in the treatment of animals. 
     In one aspect of the invention, a prosthetic valve is provided. The prosthetic valve includes a support member and a valvular body attached to the support member. The prosthetic valve has an expanded state in which the support member has a cross-sectional shape that is generally cylindrical or generally oval and which has a first cross-sectional dimension (e.g., diameter), and a contracted state in which the support member has a second cross-sectional dimension (e.g., diameter) smaller than the first. The prosthetic valve is in its contracted state during delivery of the prosthetic valve to a treatment location, and in its expanded state after deployment at the treatment location. Preferably, the cross-sectional dimension of the support member in its expanded state is sufficiently large, and the support member possesses sufficient radial strength, to cause the support member to positively physically engage the internal surface of the body lumen, such as the aortic valve annulus or another biologically acceptable aortic position (e.g., a location in the ascending or descending aorta), thereby providing a strong friction fit. 
     Specifically, in several preferred embodiments, the support member has a cross-sectional dimension that is slightly larger than the dimension of the treatment location, such as a body lumen. For example, if the treatment location is the root annulus of the aortic valve, the support member may be provided with a cross-sectional dimension that is from about 0 to about 25% larger than the cross-sectional dimension of the valve annulus. Cross-sectional dimensions even larger than 25% greater than that of the body lumen may also be used, depending upon the nature of the treatment location. As described in more detail below, once deployed, the support member extends to its full cross-sectional dimension—i.e., it does not compress radially due to the radial force imparted by the lumen or other tissue. Rather, the support member will expand the cross-sectional dimension of the lumen or other tissue at the treatment location. In this way, the support member reduces the possibility of fluid leakage around the periphery of the device. In addition, due to the strength of the interference fit that results from the construction of the device, the support member will have proper apposition to the lumen or tissue to reduce the likelihood of migration of the device once deployed. 
     In several embodiments, the support member is a structure having at least two peripheral segments, at least two of which segments are connected to each other by a foldable junction. As used herein, the term “segment” refers to a constituent part into which the support member is divided by foldable junctions or other junctions connecting adjacent segments. In several embodiments, each segment comprises a panel, with two or more connected panels making up the support member. Alternatively, and without intending to otherwise limit the descriptions provided, segments may comprise beams, braces, struts, or other structural members extending between the foldable junctions provided on the support member. Any of these (or any other) alternative structures, or any combinations thereof, may be provided as one or more segments of the support member. 
     In the above embodiments of the support member, the foldable junction may comprise any structural member that allows two adjacent segments to partially or completely fold one upon another. In several preferred embodiments, the foldable junction comprises a hinge. Suitable hinges include mechanical hinges, membrane hinges, living hinges, or combinations of such hinges. 
     In addition to the foldable junctions, two adjacent panels may be connectable by a selectively locking junction, such as pairs of opposed tabs and slots. In embodiments that include three or more segments, a combination of foldable junctions and locking junctions may be used. 
     The support structure may be provided with one or more anchoring members that are adapted to engage the internal wall of the body lumen. Each anchoring member may comprise a barb, a tooth, a hook, or any other member that protrudes from the external surface of the support structure to physically engage the internal wall of the body lumen. Alternatively, the anchoring member may comprise an aperture formed in the support structure that allows tissue to invaginate therethrough, i.e., the outward radial force of the support member against the vessel wall causes the frame portion of the support member to slightly embed into the vessel wall, thereby causing some of the tissue to penetrate through the aperture into the interior of the support member. The tissue invagination acts to anchor the support structure in place. An anchoring member may be selectively engageable, such as by an actuator, or it may be oriented so as to be permanently engaged. Alternatively, the anchoring member may be self-actuating, or it may be deployed automatically during deployment of the support member. 
     The anchoring member advantageously may perform functions in addition to engaging the internal wall of the body lumen. For example, the anchoring member may ensure proper positioning of the support structure within the body lumen. It may also prevent migration or other movement of the support structure, and it may provide additional or enhanced sealing of the support structure to the body lumen, such as by creating better tissue adherence. 
     The support structure may also be provided with an optional sealing member, such as a gasket. The sealing member preferably is fixed to the external surface of the support structure around all or a portion of the circumference of the support structure, and serves to decrease or eliminate the flow of fluids between the vessel wall and the support member. The sealing member may comprise a relatively soft biocompatible material, such as a polyurethane or other polymer. Preferably, the sealing member is porous or is otherwise capable of expanding or swelling when exposed to fluids, thereby enhancing the sealing ability of the sealing member. The sealing member may include a functional composition such as an adhesive, a fixative, or therapeutic agents such as drugs or other materials. 
     As an additional option, a coating may be applied to or created on any of the surfaces of the support member. Coatings may be applied or created to provide any desired function. For example, a coating may be applied to carry an adhesive, a fixative, or therapeutic agents such as drugs or other materials. Coatings may be created on the external surface of the support member to facilitate tissue penetration (e.g., ingrowth) into the support structure. Coatings may also be provided to promote sealing between the support member and the native tissue, or to reduce the possibility that the support member may migrate from its intended location. Other coating functions will be recognized by those skilled in the art. 
     The valvular body may be of a single or multi-piece construction, and includes a plurality of leaflets. The valvular body may be attached either to the internal or external surface of the support structure. In the case of a single-piece construction, the valvular body includes a base portion that is attachable to the support structure, and a plurality of (and preferably three) leaflets extending from the base portion. In the case of a multi-piece construction, the valvular body includes a plurality of (preferably three) members, each including a base portion that is attachable to the support structure and a leaflet portion. In either case, the base portion(s) of the valvular body are attached to a portion of the internal or external surface of the support structure, and the leaflets extend away from the base portion and generally inwardly toward each other to form the valve. 
     The valvular body, either single-piece or multi-piece, may comprise a homogeneous material, for example, a polymer such as polyurethane or other suitable elastomeric material. Alternatively, the valvular body may comprise a coated substrate, wherein the substrate comprises a polymer (e.g., polyester) or metallic (e.g., stainless steel) mesh, and the coating comprises a polymer such as polyurethane or other suitable elastomeric material. Other suitable constructions are also possible. 
     Alternatively, the valvular body may comprise human (including homograft or autograft) or animal (e.g., porcine, bovine, equine, or other) tissue. 
     The valvular body may be attached to the support structure by any suitable mechanism. For example, an attachment lip formed of a polymer, fabric, or other flexible material may be molded or adhered to the surface of the support member, and the valvular body sewn, adhered, or molded onto the attachment lip. Alternatively, an edge portion of the valvular body may be sandwiched between a pair of elastomeric strips that are attached to the surface of the support member. Other and further attachment mechanisms may also be used. 
     As described above, each of the foregoing embodiments of the prosthetic valve preferably has a fully expanded state for deployment within a body lumen, and a contracted state for delivery to the lumen in a minimally invasive interventional procedure through the patient&#39;s vasculature. In the fully expanded state, each of the segments of the support member is oriented peripherally and adjacent to one another, attached to each adjacent segment by a foldable junction or an locking junction. In the contracted state, the segments are folded together at the foldable junctions and, preferably, then formed into a smaller diameter tubular structure. The contracted state may be achieved in different combinations and manners of folding and rolling the segments and junctions, depending on the particular structure of the prosthetic valve. 
     For example, in one embodiment, the prosthetic valve comprises a generally cylindrical support member made up of three panels, with each panel connected to its adjacent panel by a hinge. The hinges may be mechanical hinges, membrane hinges, living hinges, or a combination of such hinges. In its fully expanded state, each panel of the prosthetic valve is an arcuate member that occupies approximately 120°, or one third, of the circular cross-section of the cylindrical support member. Alternatively, one or more of the panels may span a smaller portion of the cylindrical support member, while the other panel(s) are relatively larger. For example, a relatively shorter panel may be provided on a side of the valve corresponding to the non-coronary native valve leaflet, which is generally smaller than the other native valve leaflets. A valvular body is attached to the internal surface of each of the three panels. The contracted state is obtained by first inverting each of the panels at its centerline, i.e., changing each panel from a convex shape to a concave shape by bringing the centerline of each panel toward the longitudinal axis running through the center of the generally cylindrical support member. This action causes the foldable junctions to fold, creating a vertex at each foldable junction. For the foregoing three panel support member, a three vertex star-shaped structure results. In the case of a four panel support member, a four vertex star-shaped structure would result. The valvular body, which is formed of generally flexible, resilient materials, generally follows the manipulations of the support member without any substantial crimping, tearing, or permanent deformation. 
     Inversion of the panels results in a structure having a relatively smaller maximum transverse dimension than that of the fully expanded structure. To further reduce the transverse dimension, each vertex is curled back toward the central axis to create a plurality of lobes equi-spaced about the central axis, i.e., in the three-panel structure, three lobes are formed. The resulting multi-lobe structure has an even further reduced maximum transverse dimension, and represents one embodiment of the contracted state of the prosthetic valve. 
     In another embodiment, the prosthetic valve comprises a generally cylindrical support member made up of three panels defining three junctions, two of which comprise hinges, and one of which comprises a set of locking tabs and slots. The hinges may be mechanical hinges, membrane hinges, living hinges, other hinge types, or a combination of such hinges. As with the prior embodiment, in its fully expanded state, each panel of the prosthetic valve is an arcuate member that occupies approximately 120°, or one third, of the circular cross-section of the cylindrical support member. A valvular body is attached to the internal surface of each of the three panels, with at least one separation in the valvular body corresponding with the location of the locking junction on the support member. The contracted state in this alternative embodiment is obtained by first disengaging the locking tabs and slots at the non-hinge junction between a first two of the panels. Alternatively, the locking tabs and slots may be simply unlocked to permit relative motion while remaining slidably engaged. The third panel, opposite the non-hinge junction, is then inverted, i.e., changed from convex to concave by bringing the centerline of the panel toward the longitudinal axis running through the center of the generally cylindrical support member. The other two panels are then nested behind the third panel, each retaining its concave shape, by rotating the hinges connecting each panel to the third panel. The resulting structure is a curved-panel shaped member. The valvular body, which is formed of generally flexible, resilient materials, generally follows the manipulations of the support member without any substantial crimping, tearing, or permanent deformation. The structure is then curled into a tubular structure having a relatively small diameter in relation to that of the fully expanded prosthetic valve, and which represents an alternative embodiment of the contracted state of the prosthetic valve. 
     In still another embodiment, the prosthetic valve comprises a generally oval-shaped support member made up of two panels, with a hinge provided at the two attachment edges between the panels. The hinges may be mechanical hinges, membrane hinges, living hinges, or a combination of such hinges. A valvular body is attached to the internal surface of each of the two panels. The contracted state is obtained by first inverting one of the two panels at its centerline, i.e., changing the panel from a convex shape to a concave shape by bringing the centerline of the panel toward the longitudinal axis running through the center of the generally oval support member. This action causes the foldable junctions to fold, creating a vertex at each foldable junction, and causes the two panels to come to a nested position. The valvular body, which is formed of generally flexible, resilient materials, generally follows the manipulations of the support member without any substantial crimping, tearing, or permanent deformation. The structure is then curled into a tubular structure having a relatively small diameter in relation to that of the fully expanded prosthetic valve, and which represents another alternative embodiment of the contracted state of the prosthetic valve. 
     Several alternative support members are also provided. In one such alternative embodiment, the support structure is a generally tubular member constructed such that it is capable of transforming from a contracted state having a relatively small diameter and large length, to an expanded state having a relatively large diameter and small length. The transformation from the contracted state to the expanded state entails causing the tubular member to foreshorten in length while expanding radially. The forced foreshortening transformation may be achieved using any of a wide range of structural components and/or methods. In a particularly preferred form, the support structure comprises an axially activated support member. The axially activated support member includes a generally tubular body member formed of a matrix of flexible struts. In one embodiment, struts are arranged in crossing pairs forming an “X” pattern, with the ends of a first crossing pair of struts being connected to the ends of a second crossing pair of struts by a band connector, thereby forming a generally cylindrical member. Additional generally cylindrical members may be incorporated into the structure by interweaving the struts contained in the additional cylindrical member with one or more of the struts included in the first cylindrical member. An axial member is connected to at least two opposed band connectors located on opposite ends of the structure. When the axial member is decreased in length, the support member is expanded to a large diameter state, accompanied by a degree of foreshortening of the support member. When the axial member is increased in length, the support member is contracted to a smaller diameter state, accompanied by a degree of lengthening of the support member. The expanded state may be used when the support member is deployed in a body lumen, and the contracted state may be used for delivery of the device. A valvular body, as described above, may be attached to the internal or external surface of the support member. 
     In the foregoing embodiment, the axial member may be replaced by a circumferential member, a spirally wound member, or any other structure adapted to cause the tubular member to foreshorten and thereby to transform to the expanded state. The axial or other member may be attached to opposed connectors, to connectors that are not opposed, or connectors may not be used at all. Alternatively, the support member may be formed of a plurality of braided wires or a single wire formed into a tubular shape by wrapping around a mandrel. In either case, the structure is caused to radially expand by inducing foreshortening. 
     As a further alternative, the support structure (or portions thereof) may be self-expanding, such as by being formed of a resilient or shape memory material that is adapted to transition from a relatively long tubular member having a relatively small cross-sectional dimension to a relatively shorter tubular member having a relatively larger cross-sectional dimension. In yet further alternatives, the support structure may partially self-expand by foreshortening, after which an expansion device may be used to cause further radial expansion and longitudinal foreshortening. 
     In another alternative embodiment, the support member comprises a multiple panel hinged ring structure. The multiple panel hinged ring structure includes a plurality of (preferably three) circumferential rings interconnected by one or more (preferably three) longitudinal posts. Each ring structure, in turn, is composed of a plurality of segments, such as curved panels, each connected to its adjacent panels by a junction member, such as a polymeric membrane hinge. The hinges are rotated to transform the structure from an expanded state for deployment, to a contracted state for delivery. A valvular body, as described elsewhere herein, is attached to the internal or external surface of the support member. 
     In still another alternative embodiment, the support member comprises a collapsing hinged structure. The collapsing hinged structure includes a plurality of (preferably about twenty-four) panels arranged peripherally around the generally tubular structure, each panel having a tab on its edge that overlaps and engages a mating tab on the opposed edge of the adjacent panel, interlocking the adjacent panels. An elastic membrane is attached to an external surface of adjacent panels and provides a force biasing the adjacent panels together to assist the tabs in interlocking each adjacent pair of panels. Preferably, the elastic membrane is attached to the main body of each panel, but not at the opposed edges. Thus, the tabs may be disengaged and the panels rotated to form a vertex at each shared edge, thereby defining a multi-vertex “star” shape that corresponds with the contracted state of the support member. The support member is transformed to its expanded state by applying an outward radial force that stretches the elastic membrane and allows the tabs to re-engage. A valvular body, as described elsewhere herein, is attached to the internal or external surface of the support member. 
     The various support members may be incorporated in a prosthetic valve, as described above, by attaching a valvular body to the external or internal surface of the support member. In the alternative, any of the foregoing support members may be utilized without a valvular body to provide a support or scaffolding function within a body lumen, such as a blood vessel or other organ. For example, the multi-segment, multi-hinged support member may be used as a scaffolding member for the treatment of abdominal aortic aneurisms, either alone, or in combination with another support member, graft, or other therapeutic device. Other similar uses are also contemplated, as will be understood by those skilled in the art. 
     Each of the foregoing prosthetic valves and support members is adapted to be transformed from its expanded state to its contracted state to be carried by a delivery catheter to a treatment location by way of a minimally invasive interventional procedure, as described more fully elsewhere herein. 
     In other aspects of the invention, delivery devices for delivering a prosthetic valve to a treatment location in a body lumen are provided, as are methods for their use. The delivery devices are particularly adapted for use in minimally invasive interventional procedures, such as percutaneous aortic valve replacements. The delivery devices include an elongated delivery catheter having proximal and distal ends. A handle is provided at the proximal end of the delivery catheter. The handle may be provided with a knob, an actuator, a slider, other control members, or combinations thereof for controlling and manipulating the catheter to perform the prosthetic valve delivery procedure. A retractable outer sheath may extend over at least a portion of the length of the catheter. Preferably, a guidewire lumen extends proximally from the distal end of the catheter. The guidewire lumen may extend through the entire length of the catheter for over-the-wire applications, or the guidewire lumen may have a proximal exit port closer to the distal end of the catheter than the proximal end for use with rapid-exchange applications. 
     The distal portion of the catheter includes a carrier adapted to receive and retain a prosthetic valve and to maintain the prosthetic valve in a contracted state, and to deploy the prosthetic valve at a treatment location within a body lumen. In one embodiment, the distal portion of the catheter is provided with a delivery tube having a plurality of longitudinal slots at its distal end, and a gripper having a longitudinal shaft and a plurality of fingers that extend longitudinally from the distal end of the gripper. Preferably, the delivery tube has the same number of longitudinal slots, and the gripper includes the same number of fingers, as there are segments on the prosthetic valve to be delivered. The longitudinal slots on the distal end of the delivery tube are equally spaced around the periphery of the tube. Similarly, as viewed from the distal end of the gripper, the fingers are arranged in a generally circular pattern. For example, in the case of three fingers, all three are spaced apart on an imaginary circle and are separated from each other by approximately 120°. In the case of four fingers, the fingers are separated from each other by approximately 90°, and so on. The spacing and orientation of the longitudinal slots and fingers may vary from these preferred values while still being sufficient to perform the delivery function in the manner described herein. The gripper is slidably and rotatably received within the delivery tube, and the delivery tube is internal of the outer sheath. The outer sheath is retractable to expose at least the longitudinal slots on the distal portion of the delivery tube. The gripper is able to be advanced at least far enough to extend the fingers distally outside the distal end of the delivery tube. 
     In alternative embodiments of the above delivery device, the gripper fingers may comprise wires, fibers, hooks, sleeves, other structural members extending distally from the distal end of the gripper, or combinations of any of the foregoing. As described below, a primary function of the fingers is to retain a prosthetic valve on the distal end of the gripper, and to restrain segments of the support member of the valve in an inverted state. Accordingly, any of the above (or other) structural members able to perform the above function may be substituted for the fingers described above. 
     An optional atraumatic tip or nosecone may be provided at the distal end of the device. The tip is preferably formed of a relatively soft, elastomeric material and has a rounded to conical shape. A central lumen is provided in the tip to allow passage of the guidewire. The shape and physical properties of the tip enhance the ability of the delivery device to safely pass through the vasculature of a patient without damaging vessel walls or other portions of the anatomy. In addition, the atraumatic tip may enhance the ability of the distal portion of the device to cross the native heart valve when the leaflets of the native valve are fully or partially closed due to calcification from disease or other disorder. 
     The delivery device is particularly adapted for use in a minimally invasive surgical procedure to deliver a multi-segment prosthetic valve, such as those described above, to a body lumen. To do so, the prosthetic valve is first loaded into the delivery device. In the case of a prosthetic valve having a three segment support member, the delivery tube will have three longitudinal slots at its distal end, and the gripper will be provided with three fingers. The prosthetic valve is loaded into the delivery device by first inverting the three segments to produce a three vertex structure. Inverting of the prosthetic valve segments may be performed manually, or with the aid of a tool. The prosthetic valve is then placed onto the distal end of the gripper, which has been previously extended outside the distal end of the delivery tube, with each of the three fingers retaining one of the inverted segments in its inverted position. The gripper and fingers, with the prosthetic valve installed thereon, are then retracted back into the delivery tube. During the retraction, the gripper and fingers are rotationally aligned with the delivery tube such that the three vertices of the prosthetic valve align with the three longitudinal slots on the distal end of the delivery tube. When the gripper and fingers are fully retracted, each of the three vertices of the prosthetic valve extends radially outside the delivery tube through the longitudinal slots. The gripper is then rotated relative to the delivery tube (or the delivery tube rotated relative to the gripper), which action causes each of the folded segments of the prosthetic valve to engage an edge of its respective delivery tube slot. Further rotation of the gripper relative to the delivery tube causes the folded segments to curl back toward the longitudinal axis of the prosthetic valve internally of the delivery tube, creating three lobes located fully within the delivery tube. The prosthetic valve is thereby loaded into the delivery device. The outer sheath may then be advanced over the distal portion of the catheter, including the delivery tube, to prepare the delivery device for use. 
     The prosthetic valve is delivered by first introducing a guidewire into the vascular system and to the treatment location of the patient by any conventional method, preferably by way of the femoral artery. Optionally, a suitable introducer sheath may be advanced to facilitate introduction of the delivery device. The delivery catheter is then advanced over the guidewire to the treatment location. The outer sheath is then retracted to expose the delivery tube. The gripper is then rotated relative to the delivery tube (or the delivery tube rotated relative to the gripper), thereby causing the folded segments of the prosthetic valve to uncurl and to extend radially outward through the longitudinal slots of the delivery tube. The delivery tube is then retracted (or the gripper advanced) to cause the prosthetic valve (restrained by the fingers) to advance distally out of the delivery tube. The gripper is then retracted relative to the prosthetic valve, releasing the prosthetic valve into the treatment location. Preferably, the inverted segments then revert to the expanded state, causing the valve to lodge against the internal surface of the body lumen (e.g., the aortic valve root or another biologically acceptable aortic position). Additional expansion of the prosthetic valve may be provided, if needed, by a suitable expansion member, such as an expansion balloon or an expanding mesh member (described elsewhere herein), carried on the delivery catheter or other carrier. 
     In another embodiment of the delivery device, the distal portion of the catheter includes a restraining sheath, an orientation sheath, a plurality of grippers, an expander, and a plurality of struts. An optional atraumatic tip or nosecone, as described above, may also be fixed to the distal end of the device. Each of the grippers includes a wire riding within a tube, and a tip at the distal end of the tube. The wire of each gripper is adapted to engage the vertex of a prosthetic valve support member having multiple segments, and to selectively restrain the prosthetic valve in a contracted state. The expander is adapted to selectively cause the grippers to expand radially outwardly when it is actuated by the user by way of an actuator located on the handle. 
     The prosthetic valve may be loaded into the delivery device by contracting the prosthetic valve (either manually or with a tool) by inverting each panel and then attaching each vertex to a respective gripper on the delivery device. The grippers receive, retain, and restrain the prosthetic valve in its contracted state. The gripper assembly having the prosthetic valve installed is then retracted into each of the orientation sheath and the restraining sheath to prepare the device for insertion into the patient&#39;s vasculature. The device is then advanced over a guidewire to a treatment location, such as the base annulus of the native aortic valve or another biologically acceptable aortic position (e.g., a location in the ascending or descending aorta). The restraining sheath is then retracted to allow the prosthetic valve to partially expand (e.g., to about 85% of its full transverse dimension), where it is constrained by the orientation sheath. The prosthetic valve is then finally positioned by manipulation of the grippers, after which the orientation sheath is retracted and the grippers released. The prosthetic valve then is fixedly engaged in the treatment location. 
     In yet another embodiment of the delivery device, the distal portion of the catheter includes one or more restraining tubes having at least one (and preferably two) adjustable restraining loops. The restraining tube(s) extend distally from a catheter shaft out of the distal end of the delivery device, and each restraining loop is a wire or fiber loop that extends transversely from the restraining tube. Each restraining loop is a flexible loop capable of selectively restraining a contracted prosthetic valve. The restraining loop may be selectively constricted or released by a control member, such as a knob, located on the handle of the device, or by another external actuation member. An optional retractable outer sheath may be provided to cover the distal portion of the catheter. Additionally, an optional atraumatic tip or nosecone, as described above, may be provided at the distal end of the device. 
     The prosthetic valve may be loaded onto the delivery device by contracting the prosthetic valve (either manually or with a tool) into its contracted state, for example, by inverting each panel and curling each inverted panel into a lobe. The contracted prosthetic valve is then placed onto the restraining tube(s) and through the one or more restraining loops. The loops are constricted around the contracted prosthetic valve, thereby restraining the prosthetic valve in its contracted state. The optional outer sheath may then be advanced over the prosthetic valve and the restraining tube(s) to prepare the delivery device for use. The device is then advanced over a guidewire to a treatment location, such as the base annulus of the native aortic valve or another biologically acceptable aortic position (e.g., a location in the ascending or descending aorta). The restraining sheath is then retracted to expose the contracted prosthetic valve. The restraining loops are released, such as by rotating the control knob, thereby releasing the prosthetic valve and allowing it to self-expand. The prosthetic valve is thereby fixedly engaged in the treatment location. An expansion member may be advanced to the interior of the prosthetic valve (or retracted from distally of the valve) and expanded to provide additional expansion force, if needed or desired. 
     In each of the foregoing device delivery methods, the user is able to deploy the device in a careful, controlled, and deliberate manner. This allows the user to, among other things, pause the delivery procedure and reposition the device if needed to optimize the delivery location. This added degree of control is a feature that is not available in many of the previous percutaneous device delivery methods. 
     In another aspect of the invention, an expansion member is provided for performing dilation functions in minimally invasive surgical procedures. For example, the expansion member may be used in procedures such as angioplasty, valvuloplasty, stent or other device placement or expansion, and other similar procedures. In relation to the devices and methods described above and elsewhere herein, the expansion member may be used to provide additional expansion force to the support members used on the prosthetic valves described herein. 
     In one embodiment, the expansion member comprises a plurality of inflation balloons oriented about a longitudinal axis. Each inflation balloon is connected at its proximal end by a feeder lumen to a central lumen that provides fluid communication between the inflation balloons and a source of inflation media associated with a handle portion of a catheter. The central lumen itself is provided with a guidewire lumen to allow passage of a guidewire through the expansion member. A flexible member is attached to the distal end of each of the inflation balloons, and also includes a guidewire lumen. In a preferred embodiment, the expansion member includes three inflation balloons, although fewer or more balloons are possible. The balloons may each be inflated individually, all together, or in any combination to obtain a desired force distribution. The multiple inflation balloon structure provides a number of advantages, including the ability to provide greater radial forces than a single balloon, and the ability to avoid occluding a vessel undergoing treatment and to allow blood or other fluid to flow through the device. 
     In an alternative embodiment, the expansion member comprises a flexible, expandable mesh member. The expandable mesh member includes a shaft and a cylindrical woven mesh member disposed longitudinally over the shaft. A distal end of the cylindrical mesh member is attached to the distal end of the shaft. The proximal end of the cylindrical mesh member is slidably engaged to the shaft by a collar proximally of the distal end. As the collar is advanced distally along the shaft, the body of the cylindrical mesh member is caused to expand radially, thereby providing a radially expansion member. Alternatively, the proximal end of the mesh member may be fixed to the shaft and the distal end may have a collar engagement allowing it to advance proximally along the shaft to cause the mesh member to expand radially. Still further, each of the proximal and distal ends of the mesh member may be slidably engaged to the shaft, and each moved toward the other to cause radial expansion. 
     In additional exemplary embodiments, the a support structure can be configured with various external seals, various anchoring members, various types of hinges, and various native leaflet control members for applications where the support structure is used in valve replacement. 
     Other aspects, features, and functions of the inventions described herein will become apparent by reference to the drawings and the detailed description of the preferred embodiments set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1A  is a perspective view of a prosthetic valve in accordance with the present invention. 
         FIG. 1B  is a perspective view of a support member in accordance with the present invention. 
         FIG. 2A  is a perspective view of a support member having illustrating inverted panels. 
         FIG. 2B  is a top view of the support member of  FIG. 2A . 
         FIG. 2C  is a top view of a support member in a contracted state. 
         FIG. 3A  is a perspective view of another support member in accordance with the present invention. 
         FIG. 3B  is a close-up view of a hinge on the support member of  FIG. 3A . 
         FIG. 3C  is a close-up view of an locking tab and slot on the support member of  FIG. 3A . 
         FIG. 3D  is a perspective view of the support member shown in  FIG. 3A , illustrating inversion of a panel. 
         FIG. 3E  is a perspective view of the support member shown in  FIG. 3A , illustrating a nested arrangement of the three panels. 
         FIG. 3F  is a perspective view of the support member shown in  FIG. 3A , illustrating a contracted state of the support member. 
         FIG. 3G  is an end view of the support member shown in  FIG. 3A , illustrating a contracted state of the support member. 
         FIG. 3H  is a top view of another support member, illustrating a nested arrangement of the three panels. 
         FIG. 3I  is a side view of the support member shown in  FIG. 3H . 
         FIG. 4A  is a perspective view illustrating a hinge connecting two panels of a support member. 
         FIG. 4B  is a perspective view of the hinge shown in  FIG. 4A , illustrating the hinge in is folded state. 
         FIG. 4C  is a perspective view of another hinge connecting two panels of a support member. 
         FIG. 4D  is a perspective view of another hinge connecting two panels of a support member. 
         FIG. 5A  is a perspective view of a support member having inverted panels, illustrating removable hinge pins. 
         FIG. 5B  is a perspective view of a support member after separation of its three panels. 
         FIG. 6  is a perspective view of another support member. 
         FIG. 7  is a close-up view of an attachment mechanism for attaching a valvular body to a support member. 
         FIG. 8A  is a perspective view of a valvular body. 
         FIG. 8B  is a perspective view showing separate leaflets of the valvular body of  FIG. 8A . 
         FIG. 9A  is a perspective view of an axially activated support member in its contracted state. 
         FIG. 9B  is a perspective view of the axially activated support member of  FIG. 9A , shown in its expanded state. 
         FIG. 10A  is a perspective view of a multiple panel hinged ring prosthetic valve. 
         FIG. 10B  is an end view of the prosthetic valve shown in  FIG. 10A . 
         FIG. 10C  is a perspective view of a multiple panel hinged ring support member. 
         FIG. 10D  is an end view of the support member shown in  FIG. 10C . 
         FIG. 10E  is a close-up view of a panel contained on the support member shown in  FIG. 10C . 
         FIG. 10F  is a perspective view of a portion of a ring of panels contained on the support member shown in  FIG. 10C . 
         FIG. 10G  is a top view of a ring of panels contained on a support member, shown in a contracted state. 
         FIG. 10H  is a perspective view of the support member shown in  FIG. 10C , shown in the contracted state. 
         FIG. 10I  is a top view of a ring of panels contained on another support member, shown in a contracted state. 
         FIG. 10J  is a perspective view of the support member shown in  FIG. 10I , shown in the contracted state. 
         FIG. 11A  is a perspective view of a collapsing hinged support member, shown in its expanded state. 
         FIG. 11B  is a perspective view of the collapsing hinged support member, shown in its contracted state. 
         FIG. 11C  is a close-up view of a portion of the collapsing hinged support member shown in  FIG. 11A . 
         FIG. 12A  is a perspective view of a prosthetic valve retained on a delivery device. 
         FIG. 12B  is a top view of the prosthetic valve and delivery device shown in  FIG. 12A . 
         FIG. 12C  is a side view of the prosthetic valve and delivery device shown in  FIG. 12A . 
         FIG. 12D  is another top view of the prosthetic valve and delivery device shown in  FIG. 12A . 
         FIG. 12E  is another top view the prosthetic valve and delivery device shown in  FIG. 12A . 
         FIG. 12F  is another top view of the prosthetic valve and delivery device shown in  FIG. 12A . 
         FIG. 13A  is a perspective view, shown in partial cross-section, of a prosthetic valve delivery device. 
         FIG. 13B  is a close-up view of a portion of the prosthetic valve delivery device shown in  FIG. 13A . 
         FIG. 13C  is another close-up view of a portion of the prosthetic valve delivery device shown in  FIG. 13A   
         FIG. 13D  is another perspective view, shown in partial cross-section, of the prosthetic valve delivery device shown in  FIG. 13A . 
         FIG. 13E  is an illustration showing the delivery device of  FIG. 13A  delivering a prosthetic valve to a treatment location. 
         FIG. 14A  is a perspective view of another prosthetic valve delivery device. 
         FIG. 14B  is a close-up view of a distal portion of the prosthetic valve delivery device shown in  FIG. 14A . 
         FIG. 14C  is another close-up view of the distal portion of the prosthetic valve delivery device shown in  FIG. 14A . 
         FIG. 14D  is an illustration showing the delivery device of  FIG. 14A  delivering a prosthetic valve to a treatment location. 
         FIG. 14E  is another illustration showing the delivery device of  FIG. 14A  delivering a prosthetic valve to a treatment location. 
         FIG. 15A  is a perspective view of another prosthetic valve delivery device. 
         FIG. 15B  is a close-up view of a distal portion of the prosthetic valve delivery device shown in  FIG. 15A . 
         FIG. 16A  is a perspective view of another prosthetic valve delivery device. 
         FIG. 16B  is another perspective view of the prosthetic valve delivery device shown in  FIG. 16A . 
         FIG. 17A  is a perspective view of a multi-balloon expansion device. 
         FIG. 17B  is another perspective view of the multi-balloon expansion device shown in  FIG. 17A . 
         FIG. 18A  is a perspective view of an expandable mesh member, shown in its contracted state. 
         FIG. 18B  is another perspective view of the expandable mesh member of  FIG. 18A , shown in its expanded state. 
         FIG. 18C  is an illustration showing the expandable mesh member being advanced into the interior space of a prosthetic valve. 
         FIG. 18D  is another illustration showing the expandable mesh member being advanced into the interior space of a prosthetic valve. 
         FIG. 19A  is a perspective view depicting another exemplary embodiment of the valve. 
         FIGS. 19B-C  are cross-sectional views taken along line  19 - 19  of  FIG. 19A  depicting another exemplary embodiment of the valve implanted within the aortic region of a subject. 
         FIG. 19D  is a cross-sectional view depicting another exemplary embodiment of the valve support structure. 
         FIG. 20-21B  are perspective views depicting additional exemplary embodiments of the valve support structure. 
         FIG. 21C  is a bottom up view depicting another exemplary embodiment of the valve. 
         FIG. 21D-21G  are perspective views depicting additional exemplary embodiments of the valve support structure. 
         FIG. 21H  is a cross-sectional view taken along line  21 H- 21 H of  FIG. 21A  depicting another exemplary embodiment of the valve support structure. 
         FIG. 21I  is a perspective view depicting another exemplary embodiment of a valve support structure. 
         FIG. 21J  is a partial cross-sectional view depicting another exemplary embodiment of the valve support structure. 
         FIG. 22  is a perspective view depicting an additional exemplary embodiment of the valve support structure. 
         FIG. 23A-23D  are perspective views depicting additional exemplary embodiments of the valve support structure. 
         FIG. 24A-24B  are perspective views depicting additional exemplary embodiments of valve support structure. 
         FIG. 24C  is a side view depicting an exemplary embodiment of two panels. 
         FIG. 24D  is a perspective view depicting an exemplary embodiment of the valve support structure. 
         FIG. 24E  is a perspective view depicting an exemplary embodiment of the valve support structure. 
         FIGS. 24F-24G  are side views depicting an additional exemplary embodiment of the valve support structure. 
         FIG. 24H-24I  is a perspective view depicting another exemplary embodiment of the valve support structure. 
         FIG. 24J  is a side view depicting another exemplary embodiment of the valve support structure. 
         FIG. 24K  is a side view depicting another exemplary embodiment of the valve support structure. 
         FIG. 24L  is an enlarged side view of a portion of  FIG. 24K . 
         FIG. 24M-24N  are perspective views of additional exemplary embodiments of the valve support structure. 
         FIG. 24O  is an enlarged perspective view depicting a portion of  FIG. 24N . 
         FIG. 24P  is a top down view depicting another exemplary embodiment of the valve support structure. 
         FIG. 24Q-T  are perspective views depicting additional exemplary embodiments of the valve support structure. 
         FIG. 25A-25C  are perspective views depicting additional exemplary embodiments of the valve support structure. 
         FIGS. 26A-26B  are side views depicting additional exemplary embodiment of the valve support structure. 
     
    
    
     DETAILED DESCRIPTION 
     Before the present invention is described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these inventions belong. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. 
     It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
     The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. 
     As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present inventions. 
     Prosthetic Valves and Related Apparatus 
     Turning first to  FIG. 1A , an embodiment of a prosthetic valve is shown. The prosthetic valve  30  is particularly adapted for use as a replacement aortic valve, but may be used for other indications as well. As shown, the prosthetic valve  30  includes a generally cylindrical support member  32  and a valvular body  34  attached to the internal surface of the support member. Although a generally cylindrical support member is shown, support members having other than circular cross-sectional shapes, such as oval, elliptical, or irregular, may also be provided depending upon the nature of the treatment location and environment in which the prosthetic valve or the support structure are intended to be used. 
     The support member in the embodiment shown in  FIG. 1A  is made up of three generally identical curved panels  36 , with each panel spanning approximately 120° of the circular cross-section of the support member. (As noted elsewhere herein, the panels need not be generally identical in terms of size, materials, thickness, or other properties.) Each panel  36  includes a frame  38  and a semi-circular aperture  40  extending over a large portion of the central portion of the panel. The aperture  40  includes a number of interconnecting braces  42  extending across the breadth of the aperture, thereby defining a number of sub-apertures  44  between the braces. The braces define several diamond-shaped sub-apertures  46 , partial diamond-shaped sub-apertures  48 , and an elongated sub-aperture  50 . Apertures and sub-apertures of different shapes and sizes than those shown in the  FIG. 1A  embodiment are also possible. For example, in the alternative support member embodiment shown in  FIG. 1B , a single semi-circular aperture  40  is provided, with no braces and no sub-apertures. Alternatively, a panel may comprise a solid member having no apertures or sub-apertures. 
     The panels of the support member are typically the portion of the structure that engages the internal surface of the lumen at the treatment location. In the case of a prosthetic heart valve, among other functions, the panels physically engage and displace the leaflets of the native valve. The panels are also the primary portion of the structure that is in physical engagement with the body lumen and that is holding the structure in place and preventing migration. Therefore, the materials and structure of the panels are adapted, at least in part, to perform these functions. In some instances, a large aperture may be preferred, in other cases a particular bracing structure may be preferred, while in still other cases it is preferable not to have any apertures or bracing. These features may be varied to provide desired performance, depending upon the anatomical environment. 
     Each of the panels shown, and those described elsewhere herein, is preferably formed from a sheet of resilient, biocompatible material, such as stainless steel, other metals or metal alloys, resilient polymers such as plastics, or other suitable materials conventionally used for implantable medical devices. In a preferred embodiment, the panels are formed from a super-elastic shape-memory material, such as nitinol or other similar metal alloys. The panels may be molded, extruded, etched, cut, stamped or otherwise fabricated from sheets of material, or manufactured in other ways known to those skilled in the art. 
     Although the support member embodiment shown in  FIG. 1A  includes three panels, those skilled in the art will recognize that fewer or more panels may be incorporated into the support member. For example, a two panel structure may be employed, or structures having four, five, or many more panels. Alternatively, a structure may be provided having non-panel segments, such as beams, braces, struts, or other structural members extending between the foldable junctions provided on the support member. Any of these (or any other) alternative structures, or any combinations thereof, may be provided as one or more segments of the support member, provided that the structure is capable of providing the physical and structural characteristics needed to support the prosthetic valve in its intended function. 
     In addition, although each of the segments making up a support member may be identical to the other segments, it is also possible to provide segments having different physical properties. For example, in a multi-panel support member, the panels may be made up of different materials, or one or more panels may have a different size or thickness than the other panel(s), or the physical properties between the different panels may be altered in some other manner. This may be done, for example, as an accommodation for the treatment location in which the prosthetic valve is to be placed. The wall thickness of the aortic root, for example, varies around its circumference. Thus, desirable results may be obtained by providing a support member having a first panel that provides greater structural strength (or resistance to collapse) than the other panels. Other variations are also possible. 
     Turning again to  FIG. 1A , a hinge  52  is provided at the junction formed between each pair of adjacent panels. In the embodiment shown in  FIG. 1A , the hinge is a membrane hinge comprising a thin sheet of elastomeric material  54  attached to the external edge  56  of each of a pair of adjacent panels  36 . In the expanded state of the support member, as shown in  FIG. 1A , the membrane hinge maintains the side-to-side orientation of each pair of adjacent panels, preventing any significant amount of slipping or sliding between the panels. As described more fully below, the hinge  52  is also foldable so as to allow the panels  36  to invert and the edges  56  to fold together to form a vertex. The ability of the hinge (or other foldable junction member) to allow adjacent panels to invert and fold against each other at adjacent edges is a substantial feature in creating a contracted state for the support member, and the prosthetic valve. In addition, the hinge  52  (or other foldable junction) preferably is adapted to allow the support member  32  to physically conform to the internal surface of the body lumen at the treatment location. 
     As noted below and elsewhere, various types of hinges and other foldable junctions may be used in alternative embodiments. For example, and without intending to otherwise limit the descriptions contained herein, other types of hinges that may be used include standard piano hinges, living hinges, and other types of mechanical hinges. See, for example, the support member  32  shown in  FIG. 1B , in which each pair of adjacent panels  36  is connected by a standard piano hinge  58 , i.e., a long, narrow hinge with a pin  60  running the entire length of its joint that interconnects meshed sets of knuckles  62  formed on the edge of each of the pair of adjacent panels  36 . Several other alternative hinge structures are shown in  FIGS. 4A-D , in which  FIGS. 4A-B  show another membrane hinge in which the elastomeric strip  54  is attached to each of a pair of adjacent panels  36  on the internal surface of the support member  32 .  FIG. 4A  shows a portion of the support structure  32  in its expanded state, and  FIG. 4B  shows the portion of the structure after the pair of adjacent panels  36  have been folded against each other at the membrane hinge  52 , thereby forming a vertex  64 .  FIG. 4C  shows a close-up view of another standard piano hinge  58  design, similar to that shown in  FIG. 1B , showing the pin  60  and the meshing knuckles  62  formed on the edge of each of the pair of adjacent panels  36 .  FIG. 4D  shows a living hinge  66  that includes a flexible (e.g., elastomeric) hinge member  68  that is attached to each of the pair of adjacent panels  36  and that extends the length of the junction between the panels. In addition,  FIG. 5A  shows another support member (in a partially contracted condition) illustrating removable hinge pins. 
     Several alternative foldable junctions may also be used instead of hinges. For example, a section of a sheet may be etched, scored, or otherwise thinned relative to the adjacent portions of the device to provide a weakened section that allows inversion and folding of a pair of adjacent segments of the sheet, thereby providing a foldable junction. Other alternative foldable junctions are also contemplated, and will be understood by persons of skill in the art, to be suitable for use in the support members described herein. 
     Optionally, the foldable junction may be provided with a lock-out feature that allows the foldable junction to fold in a direction that allows adjacent panels to invert, as described herein, but that prevents the foldable junction from folding in the opposite direction. For example, a standard piano hinge may be constructed in a manner that provides only about 180° of rotation in a conventional manner, and attached to a pair of adjacent panels such that inward rotation is allowed, but outward rotation is prevented. Other suitable lock-out mechanisms may be possible, as will be recognized by those of skill in the art. 
     In addition, although the hinges and other foldable junctions are preferably oriented uniformly vertically (i.e., parallel to the longitudinal axis of the support member) on the periphery of the support member, other orientations are possible. For example, the hinges may be oriented horizontally (i.e., transverse) relative to the longitudinal axis, they may be oriented diagonally relative to the longitudinal axis, they may have a zig-zag or spiral orientation, or they may take on any geometric or irregular pattern. 
     Returning again to  FIG. 1A , the valvular body  34  of the embodiment shown in the figure is a flexible artificial tissue multi-leaflet structure. The artificial tissue includes a unitary polymer material or a composite of polymer overlaid onto a flexible substrate, which may be in the form of a mesh. The polymer material is any suitable flexible, biocompatible material such as those conventionally used in implantable medical devices. Preferably, the polymer material is polyurethane or another thermoplastic elastomer, although it is not limited to such materials. The material comprising the flexible mesh is preferably a flexible, shear-resistant polymeric or metallic material, such as a polyester or very fine metallic (e.g., stainless steel) mesh. The valvular body is described more fully below in relation to  FIGS. 8A-B . 
     In other embodiments, the valvular body may be formed of human tissue, such as homografts or autografts, or animal tissue, such as porcine, bovine, or equine tissue (e.g., pericardial or other suitable tissue). The construction and preparation of prosthetic tissue valvular bodies is beyond the scope of the present application, but is generally known to those of skill in the art and is readily available in the relevant technical literature. 
     The prosthetic valves described herein have an expanded state that the prosthetic valve takes on when it is in use. The  FIG. 1A  illustration shows a prosthetic valve  30  in its expanded state. In the expanded state of the prosthetic valve, the support member is fully  32  extended in its cylindrical (or alternative) shape, with each hinge  52  (or other foldable junction) in its extended, or non-folded state. As described previously, in the expanded state, the support member  32  preferably has a cross-sectional dimension (e.g., diameter) that is from about 0 to about 25% larger than that of the body lumen or other treatment location. Once deployed, the support member extends to its full cross-sectional dimension—i.e., it does not compress radially due to the radial force imparted by the lumen or other tissue. Rather, the support member will expand the cross-sectional dimension of the lumen or other tissue at the treatment location. In this way, the support member reduces the possibility of fluid leakage around the periphery of the device. In addition, due to the strength of the interference fit that results from the construction of the device, the support member will have proper apposition to the lumen or tissue to reduce the likelihood of migration of the device once deployed. The present prosthetic valves also have a contracted state that is used in order to deliver the prosthetic valve to a treatment location with the body of a patient. The contracted state generally comprises a state having a smaller transverse dimension (e.g., diameter) relative to that of the expanded state. The contracted states of several of the prosthetic valve embodiments described herein are discussed below. 
     Turning to  FIGS. 2A-C , a method for transforming a prosthetic valve from its expanded state to its contracted state is illustrated. These Figures show a three-panel support member without a valvular body attached. The method for contracting a full prosthetic valve, including the attached valvular body, is similar to that described herein in relation to the support member alone. 
     As shown in  FIGS. 2A-B , each of the panels  36  is first inverted, by which is meant that a longitudinal centerline  80  of each of the panels is forced radially inward toward the central longitudinal axis  82  of the support member. This action is facilitated by having panels formed of a thin, resilient sheet of material having generally elastic properties, and by the presence of the hinges  58  located at the junction between each pair of adjacent panels  36 . During the inversion step, the edges  56  of each of the adjacent pairs of panels fold upon one another at the hinge  58 . The resulting structure, shown in  FIGS. 2A-B , is a three-vertex  64  star shaped structure. Those skilled in the art will recognize that a similar procedure may be used to invert a four (or more) panel support member, in which case the resulting structure would be a four- (or more) vertex star shaped structure. 
     The prosthetic valve  30  may be further contracted by curling each of the vertices  64  of the star shaped structure to form a multi-lobe structure, as shown in  FIG. 2C . As shown in that Figure, each of the three vertices  64  is rotated toward the center longitudinal axis of the device, causing each of the three folded-upon edges of the adjacent pairs of panels to curl into a lobe  84 . The resulting structure, illustrated in  FIG. 2C , is a three-lobe structure that represents the fully contracted state of the prosthetic valve. Manipulation and use of the fully contracted device is described more fully below. Those skilled in the art will recognize that a similar procedure may be used to fully contract a four (or more) panel support member, in which case the resulting structure would be a four- (or more) lobed structure. 
     In the case of a two panel support member, the support member may be contracted by first inverting one of the two panels to cause it to come into close relationship with the other of the two panels to form a nested panel structure. The pair of nested panels is then rolled into a small diameter tubular member, which constitutes the contracted state of the two-panel support member. 
     Turning to  FIGS. 3A-I , another embodiment of a support member suitable for use in a prosthetic valve is shown. This embodiment is structurally similar to the preceding embodiment, but is capable of being transformed to a contracted state in a different manner than that described above. The embodiment includes three panels  36 , each having a semi-circular aperture  40 . A standard piano hinge  58  is provided at two of the junctions between adjacent pairs of panels. (See  FIG. 3B ). The third junction does not have a hinge, instead having a locking member  90 . In the embodiment shown, the locking member includes a tab  92  attached to each of the top and bottom portions of the edge of the first  36   a  of a pair of adjacent panels, and a slot  94  provided along both the top and bottom edges of the second  36   b  of the pair adjacent panels. (See  FIG. 3C ). The tabs  92  on the first panel  36   a  are able to extend through and ride in the slots  94  on the second panel  36   b , thereby allowing the first panel  36   a  to slide relative to the second panel  36   b  while remaining physically engaged to the panel, and then to slide back to the original position. A locking tab  96  may be provided on the second panel  36   b  to selectively lock the first panel tab  92  in place in the slot  94 . 
       FIGS. 3D-G  illustrate the manner in which the preceding support member is transformed to its contracted state. As shown in  FIG. 3D , the panel  36   c  situated opposite the locking junction  90  is inverted while leaving the other two panels  36   a - b  in their uninverted state. The tabs  92  on the first panels  36   a  are then slid along the slots  94  in the second panel  36   b , causing the first and second panels  36   a - b  to come into a nested arrangement behind the inverted panel  36   c , with the first panel  36   a  nested between the inverted panel  36   c  and the second panel  36   b . (See  FIG. 3E ). The nested panels are then able to be curled into a relatively small diameter tubular member  98 , as shown in  FIGS. 3F and 3G , which constitutes the contracted state of the support member. 
       FIGS. 3H-I  illustrate a similar support member in its partially contracted state in which the three panels  36   a - c  are in the nested arrangement. The support member shown in  FIGS. 3H-I  also include a plurality of brace members  42  extending through the aperture  40 , forming diamond-shaped sub-apertures  46 , partial diamond-shaped sub-apertures  48 , and an elongated sub-aperture  50 . A plurality of raised surfaces  100 , or bumps, are provided over the surfaces of each of the panels  36   a - c  to provide positive spacing for the valvular body  34  when the prosthetic valve  30  is placed in the contracted state. The positive spacing provided by the raised surfaces  100  serve to decrease the possibility of squeezing, crimping, folding, or otherwise damaging the valvular body  34  or its constituent parts when the prosthetic valve is contracted. The raised surfaces  100  (or other spacing member) of the support member may be used on any of the embodiments of the prosthetic valves described herein. 
     Turning to  FIGS. 5A-B , as described above,  FIG. 5A  illustrates a support member  32  having three panels  36   a - c  and three standard piano hinges  58  at the junctions between the three panels. The support member is shown with each of its three panels  36   a - c  in the inverted position. Each of the piano hinges  58  has a removable hinge pin  60 . When the hinge pins  60  are removed, the panels  36   a - c  may be separated from each other, as illustrated in  FIG. 5B . The ability to separate the panels may be used to facilitate surgical (or other) removal of the support member, or the prosthetic valve, or the panels may need to be separated for another purpose. Although piano hinges with removable hinge pins are shown in  FIGS. 5A-B , alternative removable hinge structures may also be used. For example, a membrane hinge having a tearable membrane strip will facilitate removal of the support member. Further alternatives may include melting or unzipping a hinge. Other removable hinge structures are also contemplated. In each of these cases, provision of a hinge that may be easily defeated by some mechanism creates that ability for the user to more easily remove or otherwise manipulate a prosthetic valve or support member for any desired purpose. 
       FIG. 6  shows another embodiment of a support member  32  suitable for use in a prosthetic valve  30 . The support member  32  includes three panels  36   a - c , each panel having an elongated aperture  50  and a semi-circular aperture  40 . The support member includes an elastomeric strip  54  at the foldable junction between each pair of adjacent panels, each of which forms a membrane hinge. A valvular body attachment lip  104  is attached to the interior surface of each of the panels  36   a - c  to facilitate attachment of the valvular body  34  to the support member  32 . The attachment lip  104  may comprise a polymer material suitable for sewing, adhering, or otherwise attaching to the valvular body. The attachment lip  104  is preferably molded or adhered onto the interior surface of each of the panels of the support member. Although the attachment lip  104  facilitates one method for attaching the valvular body to the support member, it is not the only method for doing so, and use of the attachment lip  104  is optional. 
       FIG. 7  illustrates another structure and method used to attach the valvular body to the support member panels. A first strip  110  of polymeric material is adhered to the interior surface of the edge  56  of each panel. The first strip  110  of polymeric material does not need to extend along the entire edge, but generally about half of the length. The first strip  110  is adhered with any suitable adhesive material, or it may be molded directly onto the panel  36 . An attachment lip  120  formed on the base portion of the valvular body is then attached to each of the first strips  110  of polymeric material. The attachment lips  120  may be formed on the base portion of the valvular body  34  in any of the embodiments described below, including those having a unitary structure or those having a composite structure. (A composite structure is shown in  FIG. 7 ). The attachment lips  110  may be attached to the strips of polymeric material using any suitable adhesive or any other suitable method. Next, and optionally, a second strip  112  of polymer material may be attached to the exposed surface of the valvular body attachment lip  120 , sandwiching the attachment lip  120  between the first  110  and second strips  112  of material. 
       FIGS. 8A-B  show perspective views of valvular bodies suitable for use in the prosthetic valves described herein. The valvular body  34  shown in  FIG. 8A  is of a unitary construction, while that shown in  FIG. 8B  is of a composite construction, including three separate leaflets  35   a - c . Turning first to the unitary structure embodiment shown in  FIG. 8A , the valvular body  34  includes a generally cylindrical base portion  122  that then contracts down into a generally concave portion  124  (as viewed from the interior of the valvular body). The valvular body  34  has three lines of coaptation  126  formed on the bottom of the concave portion  124 . A slit  128  is either cut or molded into each of the lines of coaptation  126  to create three valve leaflets  130  that perform the valvular fluid regulation function when the valve is implanted in a patient. An optional attachment lip  120  may be formed on the outward facing lines of coaptation  126 , to facilitate attachment of the valvular body  34  to the support member in the manner described above in relation to  FIG. 7 . 
     Turning to the composite structure embodiment shown in  FIG. 8B , each separate leaflet  35   a - c  includes a base portion  132  and a generally concave portion  134  extending from the base. Each leaflet  35   a - c  also includes a pair of top edges  136  and a pair of side edges  138 . The top edges and side edges of each leaflet  35   a - c  are positioned against the top edges and side edges of each adjacent leaflet when the composite structure embodiment is attached to an appropriate support member. 
     As described above, in either the unitary or composite construction embodiments, the valvular body may be formed solely from a single polymer material or polymer blend, or it may be formed from a substrate having a polymer coating. The materials suitable for use as the polymer, substrate, or coating are described above. Alternatively, the valvular body may comprise human or animal tissue. 
     The valvular body may be attached to the support member by any suitable method. For example, the valvular body may be attached to the support member by sewing, adhering, or molding the valvular body to an attachment lip, as described above in relation to  FIG. 6 . Or, the valvular body may be attached to the support member using the attachment strips described above in relation to  FIG. 7 . Alternatively, the valvular body may be adhered directly to the support member using an adhesive or similar material, or it may be formed integrally with the support member. Other and further suitable attachment methods will be recognized by those skilled in the art. 
     The multi-segment support member embodiments described above are suitable for use in the prosthetic valves described herein. Additional structures are also possible, and several are described below. For example, in reference to  FIGS. 9A-B , an alternative support member is illustrated. The alternative support member is a tubular member that is capable of radial expansion caused by forced foreshortening. As noted earlier herein, several structures and/or methods are available that are capable of this form of transformation, one of which is described in  FIGS. 9A-B . An axially activated support member  150  includes a generally tubular body member  152  formed of a matrix of flexible struts  154 . In the embodiment shown in the Figures, the struts  154  are arranged in crossing pairs forming an “X” pattern, with the ends of a first crossing pair of struts being connected to the ends of a second crossing pair of struts by a band connector  156 , thereby forming a generally cylindrical member. Additional generally cylindrical members are incorporated into the structure by interweaving the struts contained in the additional cylindrical member with the struts included in the first cylindrical member. An axial member  158  is connected to two opposed band connectors  156  located on opposite ends of the structure. When the axial member  158  is decreased in length, as shown in  FIG. 9B , the support member  150  is expanded to a large diameter state, accompanied by a degree of lengthwise foreshortening of the support member. When the axial member  158  is increased in length, as shown in  FIG. 9A , the support member  150  is contracted to a smaller diameter state, accompanied by a degree of lengthening of the support member. The expanded state may be used when the support member is deployed in a body lumen, and the contracted state may be used for delivery of the device. A valvular body, as described above, may be attached to the internal or external surface of the support member. 
     Another support member is shown in  FIGS. 10A-J . In this alternative embodiment, the support member comprises a multiple panel hinged ring structure  170 . The multiple panel hinged ring structure includes three circumferential rings  172  interconnected by three longitudinal posts  174 . More or fewer rings and/or posts may be used. Each ring structure, in turn, is composed of a plurality of curved panels  176 , each connected to its adjacent panel by a junction member  178 , such as a polymeric membrane hinge. The individual panels  176  have a curvature  180  about the axis of the device as well as a curvature  182  in the transverse direction. (See  FIG. 10E ). A coating material  184  maintains the panels in relation to one another, as well as providing a foldable junction  186 . The curvature of the panels in conjunction with the coating  184  maintains the ring structure in the expanded condition, as shown in  FIGS. 10A ,  10 C, and  10 D. The foldable junctions  186  are rotated to transform the structure from an expanded state  188  for deployment, to a contracted state  190  for delivery. (See  FIG. 10E-J ). A valvular body, as described elsewhere herein, may be attached to the internal or external surface of the support member. 
     In still another alternative embodiment, as shown in  FIGS. 11A-C , the support member comprises a collapsing hinged structure  200 . The collapsing hinged structure shown in the Figures includes twenty-four panels  202  arranged peripherally around the generally tubular structure, each panel having a tab  204  on its edge that overlaps and engages a mating tab  206  on the opposed edge of the adjacent panel, interlocking the adjacent panels. More or fewer panels are possible. An elastic membrane  208  is attached to an external surface of adjacent panels and provides a force biasing the adjacent panels together to assist the tabs in interlocking each adjacent pair of panels. Preferably, the elastic membrane  208  is attached to the main body of each panel  202 , but not at the opposed edges. Thus, the tabs  204 ,  206  may be disengaged and the panels  202  rotated to form a vertex  210  at each shared edge, thereby defining a multi-vertex “star” shape that corresponds with the contracted state of the support member. The support member  200  is transformed to its expanded state by applying an outward radial force that stretches the elastic membrane  208  and allows the tabs  204 ,  206  to re-engage. A valvular body, as described elsewhere herein, is attached to the internal or external surface of the support member. 
     All of the foregoing support members may be incorporated in a prosthetic valve, as described above, by attaching a valvular body to the external or internal surface of the support member. In the alternative, all of the foregoing support members may be utilized without a valvular body to provide a support or scaffolding function within a body lumen, such as a blood vessel or other organ. For example, the multi-segment, multi-hinged support member may be used as a scaffolding member for the treatment of abdominal aortic aneurisms, either alone, or in combination with another support member, graft, or other therapeutic device. Other similar uses are also contemplated, as will be understood by those skilled in the art. 
     Moreover, several additional features and functions may be incorporated on or in the prosthetic valve or its components, including the support member and the valvular body. For example, one or more anchoring members may be formed on or attached to any of the above-described support member embodiments. Each anchoring member may comprise a barb, a tooth, a hook, or any other member that protrudes from the external surface of the support structure to physically engage the internal wall of the body lumen. An anchoring member may be selectively engageable, such as by an actuator, or it may be oriented so as to be permanently in its engaged state. Alternatively, the anchoring member may comprise an aperture formed in the support structure that allows tissue to invaginate therethrough. One example of an anchoring member is illustrated in  FIGS. 13B and 13C , where a barb  358  is shown extending from the surface of a contracted prosthetic valve  30 . The barb  358  may be deflected inward while the prosthetic valve is retained in the delivery device. See  FIG. 13C . Then, upon deployment, the barb  358  is released and extends radially outward to engage the surface of the body lumen or other tissue. As noted above, other anchoring members and mechanisms are also contemplated for use with the devices described herein. 
     The prosthetic heart valves and support members described herein provide a number of advantages over prior devices in the art. For example, the prosthetic heart valves are able to be transformed to a contracted state and back to an expanded state without causing folding, tearing, crimping, or otherwise deforming the valve leaflets. In addition, unlike prior devices, the expanded state of the current device has a fixed cross-sectional size (e.g., diameter) that is not subject to recoil after expansion. This allows the structure to fit better at its treatment location and to better prevent migration. It also allows the valvular body to perform optimally because the size, shape and orientation of the valve leaflets may be designed to a known deployment size, rather than a range. Still further, because the expanded state of the support structure is of a known shape (again, unlike the prior devices), the valve leaflets may be designed in a manner to provide optimal performance. 
     Delivery Devices and Methods of Use 
     Devices for delivering a prosthetic valve to a treatment location in a body lumen are described below, as are methods for their use. The delivery devices are particularly adapted for use in minimally invasive interventional procedures, such as percutaneous aortic valve replacements.  FIGS. 14A and 15A  illustrate two embodiments of the devices. The delivery devices  300  include an elongated delivery catheter  302  having proximal  304  and distal ends  306 . A handle  308  is provided at the proximal end of the delivery catheter. The handle  308  may be provided with a knob  310 , an actuator, a slider, other control members, or combinations thereof for controlling and manipulating the catheter to perform the prosthetic valve delivery procedure. A retractable outer sheath  312  may extend over at least a portion of the length of the catheter. Preferably, a guidewire lumen extends proximally from the distal end of the catheter. The guidewire lumen may extend through the entire length of the catheter for over-the-wire applications, or the guidewire lumen may have a proximal exit port closer to the distal end of the catheter than the proximal end for use with rapid-exchange applications. The distal portion  306  of the catheter includes a carrier adapted to receive and retain a prosthetic valve in a contracted state, and to deploy the prosthetic valve at a treatment location within a body lumen. 
     Turning first to  FIGS. 12A-F , a first embodiment of a distal portion  306  of a prosthetic valve delivery device is shown. The device  300  includes a delivery tube  320  having three longitudinal slots  322  at its distal end, and a gripper  324  having a longitudinal shaft  326  and three fingers  328  that extend longitudinally from the distal end of the gripper. More or fewer longitudinal slots may be included on the delivery tube, and more or fewer fingers may be provided on the gripper. Preferably, the delivery tube  320  has the same number of longitudinal slots, and the gripper  324  includes the same number of fingers, as there are segments on the prosthetic valve to be delivered. The longitudinal slots  322  on the distal end of the delivery tube are equally spaced around the periphery of the tube. Similarly, as viewed from the distal end of the gripper  324 , the fingers  328  are arranged in an equi-spaced circular pattern. For example, in the case of three fingers, all three are equally spaced apart on an imaginary circle and are separated from each other by 120°. In the case of four fingers, the fingers would be separated from each other by 90°, and so on. 
     The gripper  324  is slidably and rotatably received within the delivery tube  320 , and the delivery tube is internal of the outer sheath (not shown in  FIGS. 12A-F ). The outer sheath is retractable to expose at least the longitudinal slots  322  on the distal portion of the delivery tube. The gripper  324  is able to be advanced at least far enough to extend the fingers  328  distally outside the distal end of the delivery tube. 
     In alternative embodiments of the above delivery device, the gripper fingers  328  may comprise wires, fibers, hooks, or other structural members extending distally from the distal end of the gripper. As described below, a primary function of the fingers is to retain a prosthetic valve on the distal end of the gripper, and to restrain segments of the support member of the valve in an inverted state. Accordingly, any of the above (or other) structural members able to perform the above function may be substituted for the fingers described above. 
     The delivery device  300  is particularly adapted for use in a minimally invasive surgical procedure to deliver a multi-segment prosthetic valve  30 , such as those described above, to a body lumen. To do so, the prosthetic valve  30  is first loaded into the delivery device  300 .  FIGS. 12A-F  illustrate the case of a prosthetic valve having a three segment support member. The prosthetic valve  30  is loaded into the delivery device  300  by first inverting the three panels  36  to produce a three vertex structure. Inverting of the prosthetic valve panels may be performed manually, or by using an inverting tool. The prosthetic valve  30  is then placed onto the distal end of the gripper  324 , which has been previously extended outside the distal end of the delivery tube  320 , with each of the three fingers  328  retaining one of the inverted panels  36  in its inverted position. (See  FIG. 12A ). The gripper  324  and fingers  328 , with the prosthetic valve  30  installed thereon, are then retracted back into the delivery tube  320 . During the retraction the gripper  324  and fingers  328  are rotationally aligned with the delivery tube  320  such that the three vertices of the prosthetic valve align with the three longitudinal slots on the distal end of the delivery tube. (See  FIG. 12B ). When the gripper  324  and fingers  328  are fully retracted, each of the three vertices of the prosthetic valve extends radially outside the delivery tube through the longitudinal slots  322 . (See  FIG. 12C ). The gripper  324  is then rotated relative to the delivery tube  320 , which action causes each of the folded segments of the prosthetic valve  30  to engage an edge of its respective delivery tube slot. (See  FIG. 12D ). Further rotation of the gripper  324  relative to the delivery tube  320  causes the folded segments to curl back toward the longitudinal axis of the prosthetic valve internally of the delivery tube, creating three lobes located fully within the delivery tube  320 . (See  FIG. 12E ). The prosthetic valve  30  is thereby loaded into the delivery device  300 . The outer sheath is then advanced over the distal portion of the catheter, including the delivery tube, to prepare the delivery device for use. 
     The prosthetic valve  30  is delivered by first introducing a guidewire into the vascular system and to the treatment location of the patient by any conventional method, preferably by way of the femoral artery. Optionally, a suitable introducer sheath may be advanced to facilitate introduction of the delivery device. The delivery catheter  302  is then advanced over the guidewire to the treatment location. The outer sheath  312  is then retracted to expose the delivery tube  320 . The gripper  324  is then rotated relative to the delivery tube  320  (or the delivery tube rotated relative to the gripper), thereby causing the folded panels of the prosthetic valve  30  to uncurl and to extend radially outward through the longitudinal slots  322  of the delivery tube  320 . The delivery tube  320  is then retracted (or the gripper advanced) to cause the prosthetic valve  30  (restrained by the fingers  328 ) to advance distally out of the delivery tube. The gripper  324  is then retracted relative to the prosthetic valve  30 , releasing the prosthetic valve  30  into the treatment location. (See  FIG. 12F ). Preferably, the inverted panels  36  then revert to the expanded state, causing the valve to lodge against the internal surface of the body lumen (e.g., the aortic valve root or another biologically acceptable aortic position). Additional expansion of the prosthetic valve may be provided, if needed, by a suitable expansion member, such as the expansion balloon or the expanding mesh member described elsewhere herein, carried on the delivery catheter  302  or other carrier. 
     Turning to  FIGS. 13A-E , another embodiment of a distal portion of a prosthetic valve delivery device is shown. The distal portion of the catheter  302  includes a restraining sheath  340 , an orientation sheath  342 , a plurality of grippers  344 , an expander  346 , and a plurality of struts  348 . Each of the grippers  344  includes a wire  350  riding within a tube  352 , and a tip  354  at the distal end of the tube. The wire  350  of each gripper  344  has an end portion  356  formed to engage the vertex of a prosthetic valve support member  32  having multiple segments, and to selectively restrain the prosthetic valve  30  in a contracted state. (See  FIG. 13B ). The expander  346  is adapted to selectively cause the grippers  344  to expand radially outwardly when it is actuated by the user by way of an actuator  310  located on the handle  308 . 
     The prosthetic valve  30  may be loaded into the delivery device  300  by contracting the prosthetic valve (either manually or with an inverting tool) by inverting each panel  36  and then attaching each vertex to a respective end portion  356  of the wire contained on each gripper  344  on the delivery device. The gripper wires  350  receive, retain, and restrain the prosthetic valve  30  in its contracted state. The gripper  344  assembly having the prosthetic valve  30  installed is then retracted into each of the orientation sheath  342  and the restraining sheath  340  to prepare the device for insertion into the patient&#39;s vasculature. The device is then advanced over a guidewire to a treatment location, such as the base annulus of the native aortic valve. (See  FIG. 13E ). The restraining sheath  340  is then retracted to allow the prosthetic valve  30  to partially expand (e.g., to about 85% of its full transverse dimension), where it is constrained by the orientation sheath  342 . The prosthetic valve  30  is then finally positioned by manipulation of the grippers  344 , after which the orientation sheath  342  is retracted and the grippers  344  released. The prosthetic valve  30  then lodges itself in the treatment location. 
     Other embodiments of the delivery device are illustrated in  FIGS. 14A-E  and  15 A-B. As shown in those Figures, the distal portion  306  of the catheter includes one or more restraining tubes  370  having at least one (and preferably two) adjustable restraining loops  372 . In the embodiment shown in  FIGS. 14A-E , the device is provided with one restraining tube  370  and two restraining loops  372 . In the embodiment shown in  FIGS. 15A-B , the device is provided with three restraining tubes  370  and two restraining loops  372 . The restraining tube(s)  370  extend distally from a catheter shaft  374  out of the distal end of the delivery device, and each restraining loop  372  is a wire or fiber loop that extends transversely of the restraining tube  370 . Each restraining loop  372  is a flexible loop capable of selectively restraining a contracted prosthetic valve. The restraining loops  372  may be selectively constricted or released by a control member, such as a knob  310 , located on the handle  308  of the device. A retractable outer sheath  376  covers the distal portion of the catheter. 
     The prosthetic valve  30  may be loaded onto the delivery device by contracting the prosthetic valve (either manually or with an inverting tool) into its contracted state, for example, by inverting each panel  36  and curling each inverted panel into a lobe. The contracted prosthetic valve is then placed onto the restraining tube(s)  370  and through the one or more restraining loops  372 . (See, e.g.,  FIG. 14B ). The loops  372  are constricted around the contracted prosthetic valve  30 , thereby restraining the prosthetic valve in its contracted state. The outer sheath  376  is then advanced over the prosthetic valve and the restraining tube(s) to prepare the delivery device for use. (See  FIG. 14C ). The device is then advanced over a guidewire to a treatment location, such as the base annulus of the native aortic valve. (See  FIG. 14D ). The restraining sheath  376  is then retracted to expose the contracted prosthetic valve  30 . The restraining loops  372  are released, such as by rotating the control knob  310 , thereby releasing the prosthetic valve  30  and allowing it to self-expand. (See  FIG. 14E ). The prosthetic valve  30  then lodges itself in the treatment location. An expansion member may be advanced to the interior of the prosthetic valve and expanded to provide additional expansion force, if needed or desired. 
     Another embodiment of the delivery device is shown in  FIGS. 16A-B . As shown there, the distal portion of the catheter includes a gripper  400  that includes a base portion  402  having three restraining members  404  extending distally from the gripper base. In the embodiment shown, each of the restraining members  404  includes a wire loop  406  extending through a sleeve  408 , with both the sleeve and the wire loop extending distally from the gripper base  402 . The wire loops  406  also extend proximally of the gripper base  402 , which is provided with a lumen  410  corresponding with each of the wire loops  406 , thereby allowing the gripper base  402  and the sleeves  404  to slide relative to the wire loops  406 . A delivery tube  412  may also be provided. As shown in the Figures, the gripper  400  is slidably received within the delivery tube  412 , and the tube has three longitudinal slots  414  corresponding with the three restraining members  404  on the gripper assembly. An atraumatic tip  416  or nosecone is attached to a central shaft  418  that extends through the center of the catheter  302  internally of the gripper  400  and the delivery tube  412 . The central shaft  418  includes a guidewire lumen to accommodate a guidewire used to assist deployment of the delivery device. 
     Although the device shown in the Figures includes three restraining members  404 , fewer or additional restraining members may be used. One function of the restraining members is to retain a prosthetic valve on the distal end of the delivery device, and to selectively maintain the valve in a contracted state. In the preferred embodiment, the number of restraining members will coincide with the number of segments (e.g., panels) included on the prosthetic valve. 
     Turning to  FIG. 16A , the delivery device  300  is shown with the delivery tube  412  and gripper  400  retracted relative to the wire loops  406 , thereby allowing the distal ends  420  of the wire loops to extend freely away from the central shaft  418 . The delivery device in this condition is adapted to have a prosthetic valve installed onto the device. To do so, the prosthetic valve  30  is first placed over the distal end of the device and the panels  36  of the valve are inverted. Alternatively, the valve panels  36  may be inverted prior to or simultaneous with placing the valve over the distal end of the delivery device. The wire loops  406  are then placed over the inverted panels  36 , and the gripper  400  is advanced to cause the sleeves  408  to physically engage the inverted panels  36 . See  FIG. 16B . The sleeves  408  have sufficient strength to maintain the prosthetic valve panels in their inverted state. The delivery tube  412  may then be advanced over the distal end of the device, with the valve panel vertices extending out of the longitudinal slots  414  formed on the delivery tube  412 . The gripper  400  may then be rotated relative to the delivery tube (or vice versa) to contract the panel vertices within the interior of the delivery tube and to thereby prepare the device for delivery of the prosthetic valve. The valve is delivered in the same manner described above in relation to the device shown in  FIGS. 12A-E . 
     As noted, each of the foregoing delivery devices is suitable for use in delivering a prosthetic heart valve or a support member, such as those described herein. In the case of a prosthetic heart valve, the delivery methods may be combined with other treatment devices, methods, and procedures, particularly procedures intended to open or treat a stenotic heart valve. For example, a valvuloplasty procedure may be performed prior to the prosthetic heart valve deployment. The valvuloplasty procedure may be performed using a conventional balloon or a cutting balloon adapted to cut scarred leaflets so that they open more easily. Other treatments, such as chemical treatments to soften calcifications or other disorders may also be performed. 
     Each of the foregoing delivery devices may be provided with a tether connecting the delivery device to the prosthetic valve or support member. The tether is preferably formed of a material and has a size sufficient to control the prosthetic valve or support member in the event that it is needed to withdraw the device during or after deployment. Preferably, the tether may be selectably disengaged by the user after deployment of the device. 
     Turning to  FIGS. 17A-B  and  18 A-D, two types of expansion members are provided for performing dilation functions in minimally invasive surgical procedures. The expansion members may be used, for example, in procedures such as angioplasty, valvuloplasty, stent or other device placement or expansion, and other similar procedures. In relation to the devices and methods described above and elsewhere herein, the expansion members may be used to provide additional expansion force to the support members used on the prosthetic valves described herein. 
     In one embodiment, illustrated in  FIGS. 17A-B , the expansion member  430  includes three elongated inflation balloons  432   a - c  oriented about a longitudinal axis  434 . Each inflation balloon  432  is connected at its proximal end by a feeder lumen  436  to a central lumen  438  that provides fluid communication between the inflation balloons  432   a - c  and a source of inflation media associated with a handle portion  308  of a catheter. The central lumen itself is provided with a guidewire lumen  440  to allow passage of a guidewire through the expansion member  430 . A flexible member  442  is attached to the distal end of each of the inflation balloons  432   a - c , and also includes a guidewire lumen. Although the expansion member shown in the Figures includes three inflation balloons, fewer or more balloons are possible. Moreover, each of the individual balloons may be inflated separately, all inflated together, or any combination thereof to obtain a desired force profile. The multiple inflation balloon structure provides a number of advantages, including the ability to provide greater radial forces than a single balloon, and the ability to avoid occluding a vessel undergoing treatment and to allow blood or other fluid to flow through the device. 
     In an alternative embodiment, shown in  FIGS. 18A-D , the expansion member  450  comprises a flexible, expandable mesh member  452 . The expandable mesh member  452  includes a shaft  454  and a cylindrical woven mesh member  452  disposed longitudinally over the shaft. A distal end  456  of the cylindrical mesh member is attached to the distal end  458  of the shaft. The proximal end  460  of the cylindrical mesh member is slidably engaged to the shaft by a collar  462  proximally of the distal end  456 . As the collar  462  is advanced distally along the shaft  454 , the body of the cylindrical mesh member  452  is caused to expand radially, thereby providing a radially expandable member. 
     Although the potential for blood flow around a properly implanted valve  30  is minimal, it may be desirable to include devices to reduce the risk of this leakage as a safeguard. As mentioned previously, the valve  30  can be configured with a sealing member to promote sealing between the valve support structure  32  and the adjacent vascular tissue wall.  FIG. 19A  is a perspective view depicting one exemplary embodiment of the valve  30  having a sealing member  512  located circumferentially around the exterior of the structure  32 . Here, the sealing member  512  is a flexible flap having a first end  513  coupled with the outer surface  514  of the support structure  32  and a second end  515 , which is preferably not coupled with the outer surface  514 . 
       FIGS. 19B-C  are cross-sectional views taken along line  21 - 21  of  FIG. 19A  depicting this exemplary embodiment implanted within the aortic region of a subject during systolic and diastolic blood flow, respectively. The sealing member  512  is preferably configured to lie adjacent to the outer surface  514  so as not to substantially obstruct systolic blood flow (direction  516 ) as depicted in  FIG. 19B . The sealing member  512  is preferably configured to deflect outwards away from the outer surface  514  and substantially seal the region between the valve structure  32  and the adjacent tissue wall  522  during diastolic blood flow (direction  517 ) as depicted in  FIG. 19C . 
       FIG. 19D  is a cross-sectional view depicting another exemplary embodiment where the sealing member  512  is a flexible V-shaped member. Here, a first side  518  of the “V” can be coupled with the outer surface  514  and the other side  519  of the “V” can be left unattached to form the seal. In these embodiments, the sealing member  512  can be formed from any flexible, biocompatible material, including polymeric materials and the like. 
       FIG. 20  is a perspective view depicting another exemplary embodiment of the valve support structure  32  where an end of the support structure has a sealing member  512  configured as a flared edge. The flared edge  512  flares away from a longitudinal axis  520  of the support structure  32  towards the tissue wall and promotes sealing under both systolic and diastolic conditions. The flared edge  512  can also anchor the support structure  32  and promote stability. The flared edge  512  can be implemented in any manner, including by curving the panels  36  to create a flared configuration, by forming the flared edge  512  with a relatively thicker panel wall and the like. 
       FIG. 21A  is a perspective view depicting another exemplary embodiment of the valve support structure  32  where the sealing member  512  is a conformable ring configured to conform to the underlying tissue (tissue wall or native valve, etc.).  FIG. 21B  is a perspective view depicting the conformable ring  512  in greater detail. Here, the conformable ring includes a flexible outer membrane, or covering  521 , as well as compressible members  522  located within membrane  521  (which would normally be obscured from view). The compressible members  522  are configured as curved flaps, which are biased to extend into an extended state (shown here), but are preferably compressible to allow the ring  512  to conform to the underlying tissue.  FIG. 21C  is a bottom up view depicting this exemplary embodiment of the valve  30  implanted within a subject, with valve leaflets  130  in a partially open position. It can be seen here that the conformable ring  512  conforms to the irregular shape of the underlying tissue  525 . It should be noted that any number of conformable rings  512  can be used or, conformable ring can be relatively larger and configured to cover a majority of the exterior surface  514  in the longitudinal direction of the valve support structure  32 . 
     The compressible members  522  can be composed of any bio-compatible, flexible, shape retensive material such as elastomers and other polymeric materials and the like. Any number of compressible members  522  can be used at any spacing within membrane  521 . The compressible members can be coupled with the outer membrane  521  or can be freely disposed within. In general, any type of compressible members  522  can be used as desired.  FIG. 21D  is a perspective view depicting another exemplary embodiment of the conformable ring  512  where each compressible member  522  is configured as a coiled portion of a continuous coil  523 .  FIG. 21E  is a perspective view depicting another exemplary embodiment where each compressible member  522  is configured as a spring. 
       FIG. 21F  is a perspective view depicting another exemplary embodiment of conformable ring  512  without outer membrane  521 . In this embodiment, each compressible member  522  is configured as a curved flap oriented so as to substantially block any blood flow around the valve support structure  32 . Here, a longitudinal axis  524  of each flap  522  is transverse (i.e., non-parallel) to the longitudinal axis  520  of the support structure  32 .  FIG. 21G  is a perspective view depicting another exemplary embodiment of conformable ring  512  without the outer membrane  521  where each compressible member is an elastomeric fiber. 
     The conformable ring  512  can also be implemented without compressible members  522 .  FIG. 21H  is a cross-sectional view taken along line  21 H- 21 H of  FIG. 21A  depicting another exemplary embodiment of conformable ring  512  where outer membrane  521  is hollow and configured to be fillable with a filler substance  525 , such as a gel, a gas, a liquid or other type of filler. The outer membrane  521  can be filled prior to implantation or filled during the implantation procedure, such as through a one-way valve located in the outer membrane  521 . The outer membrane  521  can also be solid if desired. 
       FIG. 21I  is a perspective view depicting another exemplary embodiment of a valve support structure  32  having a sealing member  512 . In this embodiment, the sealing member  512  is a flexible region in the panel  36  configured to conform to the native anatomy of the implantation site. Flexible region  512  can include one or more separations  534  in the panel wall  36 . The one or more separations  534  can be arranged to form one or more flexible struts  535 , which can preferably flex or bend to conform to the anatomy of the body lumen. A single panel  36  is shown here, but each panel  36  can include the sealing member  512 . 
       FIG. 21J  is a partial cross-sectional view depicting an exemplary embodiment of a valve support structure  32  having flexible region  512  implanted within an aortic valve region  536  of a subject. Here, the annulus  537  of the aortic valve region  536  abuts the flexible region  512  and forces flexible struts  535  inward toward the center of the valve support structure  32 . As a result, a seal is formed between the valve support structure  32  and the adjacent tissue wall, which in this example is the annulus  537 . Also, the flexible region  512  acts as an anchoring member allowing the valve support structure  32  to conform to the native anatomy and resist any tendency of the valve  30  to shift after implantation. 
       FIG. 22  is a perspective view depicting an additional exemplary embodiment of the valve support structure  32  having one or more anchoring members  538 . Here, each anchoring member  538  is configured as a fin-like protrusion. The anchoring member  538  can be coupled to or formed on the exterior surface of the valve support structure  32 , or it can be formed as a cut-out from the valve support structure  32 , which is then preferably configured to protrude outwards as depicted here. 
     It should be noted that, as mentioned above, any type of anchoring member can be used with the support structure  32  including, but not limited to barbs, tines, fins, cones, rounded bumps, and generally any other raised surface, or lowered surface such as a dimple and the like. Also, the support structure  32  can include a textured surface configured to increase surface friction between the valve support structure  32  and the surrounding tissue. The textured surface can be formed with abrasive coatings, or by texturing the surface of the valve support structure  32  directly, such as by forming the valve support structure  32  with a textured surface or by etching, cutting, sanding, brushing, denting, abrading or otherwise texturing the valve support structure  32  surface. Also, the edges of the valve support structure  32  can be configured to anchor the device, either by flaring out from the center of the device or by assuming an irregular shape, such as a with relatively pointed regions. 
       FIG. 23A  is a perspective view depicting another exemplary embodiment of the valve support structure  32 . Here, each panel  36  is coupled together with hinge  66  configured as a living hinge. Living hinge  66  can be formed from a mesh or braided material  552  composed of any substance including, but not limited to metallic substances, polymeric substances and the like. Mesh material  552  can be impregnated or coated with a lining  553 , which is preferably polymeric. 
     In this embodiment, mesh material  552  is impregnated with a polymer in a gap region  554  between panels  36 . The bare mesh material  552  located on either side of gap region  554  is coupled with the surface of adjacent panels  36 , preferably by welding, although other forms of attachment can be used. Panels  36  can have a reduced thickness in the region  555  overlapping with mesh material  552  to allow for a relatively more continuous surface. This reduced thickness region  555  can be formed via chemical or photo-chemical etching, laser cutting and the like. 
     Although shown on the outside of valve  30 , it should be noted that living hinge  66  can also be coupled on the inside of valve  30 . Also, mesh material  552  can be configured as a continuous sleeve that covers the inside and/or outside of valve  30 , where mesh material  552  is coupled with panels  36  and gap regions  554  located between adjacent panels  36  form living hinges  66 . Mesh material  552  can then be used as a substrate to which the surrounding vascular tissue can be attached. 
       FIGS. 23B-D  are perspective views depicting additional exemplary embodiments of valve  30  configured with a uni-panel construction adjustable between the expanded and contracted states without defined hinges. In this embodiment, valve  30  includes a single panel  556  with a generally cylindrical shape in the expanded state depicted in  FIG. 23B  (leaflets  130  are not shown for clarity). Panel  556  is preferably formed from a relatively rigid, yet relatively thin-walled material capable of being inverted and folded into the states depicted in  FIGS. 23C and 23D , respectively. When in the fully expanded state, panel  556  preferably exhibits sufficient hoop strength to maintain the structural integrity of the generally cylindrical shape. 
       FIGS. 24A-24T  depict additional exemplary embodiments of the valve support structure  32  where the hinges  52  between the panels  36  can be formed from interlocking members. Generally, these embodiments rely on the insertion of a deflectable tab into a slot, where the tab is allowed to undeflect into a state larger than the slot. This can effectively lock the adjacent panels  36  together. This can also provide many advantages in facilitating the construction and use of the valve support structure  32 , one of which is allowing the formation of the hinge  52  without a bonding process, such as welding, adhesive coupling and the like. 
       FIG. 24A  is a perspective view depicting an exemplary embodiment of valve support structure  32  in the fully expanded state where each hinge  52  is formed with one or more interlocking members  560 .  FIG. 24B  is a perspective view depicting one individual panel  36  of the embodiment in  FIG. 24A . Each panel  36  can include one or more apertures  583  to allow tissue invagination into panel  36  after implantation. The apertures  583  can also be used to attach the valve  30  to the surrounding vascular tissue (e.g., with sutures and the like) or to attach secondary structures to the valve  30  that promote tissue invagination. Each panel can also include one or more raised surfaces  100  to prevent the valve leaflets  130  from being compressed or damaged when valve  30  enters a contracted state. 
     As can be seen in  FIG. 24A , each interlocking member  560  includes a tab  561  and a corresponding slot  562 . Each slot  562  is configured to receive the tab  561  and allows the tab  561  to shift or swivel while located within the slot  562 . The slots  562  can be formed in a flared edge  564  of the panel  36  to facilitate the hinge motion, and act to block the hinge motion by abutting the tabs  561  once the valve  30  has been contracted into the three vertex shape. 
     As shown in  FIGS. 24A-24B , each tab  561  can be configured such that it protrudes, or lies away, from the generally cylindrical surface of the valve support structure  32  when in the fully expanded state, allowing each tab  561  to act as an anchoring member for the valve support structure  32 . When implanted, the tabs  561  engage the surrounding vascular tissue and resist movement of the valve support structure  32  within the body lumen. In this embodiment, the tabs  561  protrude at approximately sixty degrees from the adjacent panel surfaces  563 , although it should be understand that any angular protrusion (including no angular protrusion) can be used. It should be noted that the tabs  561  can have any desired shape, size, and degree of deflection from the panel surface  563  so as to optimize the anchoring effect. 
       FIG. 24C  is a side view depicting two panels  36  before being interlocked (in this and other figures described below, the panels  36  are depicted as being flat for ease of illustration). Each tab  561  has a base portion  567 , having a height  565 , and an end portion  568 , having a height  566 . As can be seen here, the lower three tabs  561  of the panels  36  as depicted each have an asymmetrical shape for optimized anchoring, whereas the uppermost tab  561  has a symmetrical shape to facilitate assembly. In each of the lower three tabs  561 , the end portion  568  is offset from the base portion  567  and the height  566  of the end portion  568  is greater than the height  565  of the base portion  567 , due to the presence of the gap  570 , which is preferably slightly wider than the thickness of the opposing panel  36 . 
       FIG. 24D  is a perspective view depicting the process of inserting these lower tabs  561  into the corresponding slots  562  (panels  36  are depicted as being flat). Each slot  562  has a thickness  573  that is slightly greater than the thickness (not shown) of the lower tabs  561  and a height  569  that is preferably slightly greater than the heights  565  and  566  of the lower tabs  561 . Preferably, each of the lower tabs  561  is inserted into the corresponding slot  562  until the slots  562  are aligned with the gaps  570 , at which point the tabs  561  are moved in the direction  571  to slide the panel  36  under the end portions  568  and into the gap  570 . 
     Referring back to  FIG. 24C , with regards to the uppermost tab  561 , the height  566  of the end portion  568  is greater than the height  565  of the base portion  567  due to the presence of the gaps  572 . The height  569  of the corresponding uppermost slot  562  is preferably approximately the same as the height  565  of the uppermost tab  561 . The uppermost slot  561  has a ‘D’ configuration, where the inner side is relatively straight while the outer side of the slot  561  is curved, giving the uppermost slot  562  a thickness  574  that is greater than the thicknesses  573  of the lower slots  562 . This ‘D’ configuration allows the insertion of the uppermost tab  561  into the slot  562 . 
       FIG. 24E  is a perspective view depicting the process of inserting the uppermost tab  561  into the corresponding uppermost slot  562  (the panels  36  are depicted as being flat). Because the height  566  of the end portion  568  is greater than the height  569  of the slot  562 , the uppermost tab  562  is preferably bent, or deflected, as shown here, to reduce the effective height  566  of the end portion  568  and allow the end portion  568  to be inserted into the slot  562 . The tab  561  is preferably biased to return to the unbent or undeflected state so that once the gaps  572  are aligned with the panel  36 , the tab  561  can be released and allowed to return to the undeflected state. Because the height  565  of the base portion  567  is approximately the same as the height  569  of the uppermost slot  562 , the uppermost tab  561  is effectively locked in position within the uppermost slot  562  and prevents the adjacent panels  36  from shifting position with respect to each other. 
       FIGS. 24F-24G  are side views depicting an additional exemplary embodiment of the valve support structure  32  having the hinges  52  formed with the interlocking members  560  (the panels  36  are depicted as being flat). Here, the upper portion of both sides of each panel  36  includes the tab  561  and slot  562 , which is configured as a notch. The tab  561  and slot  562  on each side of the panel  36  are complementary to each other, so that adjacent panels  36  can be interlocked, or latched together as depicted in  FIG. 24G . The lower portion of each panel includes the tab  561  on one side and the corresponding slot  562  on the other side. The height  565  of the base portion  567  is approximately the same as the height  569  of the slot  562 , while the height  566  of the end portion  568  is relatively greater than the heights  565  and  569 . These lower tabs  561  are configured to deflect to interlock with the slots  562  in a manner similar to that of the tab  561  and slot  562  described with respect to  FIG. 24E  and prevent shifting of the panels  36  with respect to each other. 
       FIG. 24H  is a perspective view depicting another exemplary embodiment of the valve support structure  32 . In this embodiment, each tab  561  is configured to deflect as depicted in the perspective view of  FIG. 24I  to allow interlockage with the slots  562 .  FIG. 24J  is a side view depicting the adjacent panels  36  with the tabs  561  and slots  562  in an interlocked state (the panels  36  are depicted as being flat). Here, the upper two tabs  562  have symmetrical configurations while the lower two tabs  561  have asymmetrical configurations. 
       FIG. 24K  is a side view depicting another exemplary embodiment of the valve support structure  32 . In this embodiment, each tab  561  has an asymmetric configuration with the end portion  568  having a height  566  greater than the height  565  of the base portion  567 . In this embodiment, each of the tabs  561  are configured to deflect to allow insertion into the corresponding slot  562 . 
       FIG. 24L  is an enlarged side view of the region  575  of  FIG. 24K . Here, it can be seen that each slot  562  has a generally lower portion  576 , an upper portion  577 , and a catch portion  578  located generally therebetween. A gap  579  having a thickness  580  is located between the catch portion  578  and the interface between the lower portion  576  and the upper portion  577 . The lower portion  576  has a height  582  that is approximately the same as the height  565  of the base portion  567 . The thickness  580  of the gap  579  can be approximately the same as, or slightly larger than the thickness (not shown) of the tab  561 . The upper portion  577  is offset from the lower portion  578  and together the portions  577 - 578  have a height  581  greater than the height  566  of the end portion  578  of the tab  561 , allowing the insertion of the tab  561  into the slot  562 . 
     As can be seen here, the upper portion  577  is offset from the lower portion  578  and can force the tab  561  to bend or deflect when inserted. The tab  561  is preferably biased to return to the undeflected state. After the tab  561  is fully inserted such that the gap  570  is aligned with the opposing panel  36 , the tab  562  is preferably moved in direction  571  to cause the tab  561  to slide over the opposing panel  36  and force the opposing panel  36  into the gap  570 . Because the height  582  of the lower portion  576  is preferably the same as the height  565  of the base portion  567 , once the tab  561  has been transitioned fully in direction  571 , the tab  561  is allowed to return to the undeflected state. Once in the undeflected state, the catch portion  578  abuts the upper surface of the tab  561  and effectively locks the tab  561  within the slot  562  to form the interlocking member  560 , as depicted in the perspective view of  FIG. 24M  (with the panels  36  depicted as being flat). 
       FIG. 24N  is a perspective view of another exemplary embodiment of the valve support structure  32  in the fully expanded state having the hinges  52  formed from the interlocking members  560 .  FIG. 24O  is an enlarged perspective view depicting region  581  of  FIG. 24N  in more detail.  FIG. 24P  is a top down view depicting the valve support structure  32  with the tabs  561  protruding from the surfaces  563  of the adjacent panels  36 . In this embodiment, each tab  561  is divided into a lower portion  584  and an upper portion  585  by a slit  586 . The slit  586  facilitates deflection of the tab  561  and allows for easier assembly of the valve support structure  32 . Both the portions  584  and  585  include an aperture  587  that can be used, among other things, to couple each tab  561  together. A suture or wire and the like can be routed through one or more of the apertures  587  in one or more tabs  561  to maintain all of the tabs  561  in the same plane to reduce the risk of the tabs  561  shifting or becoming disengaged or unlocked from the corresponding slot  562 . The suture or wire can also act to prevent the panels  36  from separating should one tab  561  become disengaged from the corresponding slot  562 . 
       FIG. 24Q  is a perspective view depicting another exemplary embodiment of the valve support structure  32  during assembly. Here, the valve support structure  32  includes multiple interlocking members  560  where tabs  561  are curved into a semi-looped configuration. Each curved tab  561  is preferably inserted into a corresponding slot  562  of approximately the same size. The curved tab configuration allows the swivel hinge movement and locks the tab  561  in place within the corresponding slot  562 . Here, the slots  562  can also be formed on a flared edge having one or more tabs  585  configured as anchoring members. 
       FIG. 24R  is a perspective view depicting another exemplary embodiment of the valve support structure  32 . In this embodiment, the panel  36  (depicted here as being flat) includes integral knuckles  585  for use in a piano style hinge  58  similar to that described with respect to  FIGS. 5A-B . The panel  36  also includes a tab  586  configured to act as an anchoring member. Another panel  36  having the knuckles  585  in different locations (not shown) can be coupled with the panel  36  depicted here using a pin  60  (not shown). 
     Formation of the integral knuckles  585  can be accomplished with numerous different processes. One such process is depicted in  FIGS. 24S-24T  (with the panels  36  depicted as being flat).  FIG. 24S  depicts an exemplary embodiment of the valve support structure  32  where the panel  36  includes the knuckles  585  in the form of tabs. Each tab  585  includes a base portion  588  and an end portion  589 . The panel  36  also includes the slots  587  located in positions adjacent to each tab  585 . Each slot  587  is preferably configured to receive an end portion  589 . Preferably, the tab  585  is rolled and the end portion  589  is inserted into the slot  587  as depicted in  FIG. 24T . Once fully inserted, the portion of the end portion  589  that protrudes beyond the panel  36  can be removed (e.g., trimmed) to leave the structure depicted in  FIG. 24R . Also, before or after removing the protruding end portion  589 , the tab  585  can be fixably coupled with the slot  587  with any desired technique including, but not limited to welding, brazing, bonding, mechanical press or no press fitting and the like. It should be noted that the chosen technique may depend on the type of material used to form the tab  585  (e.g., stainless steel, NITINOL, polymer and the like). 
     If the tab  585  is formed from NITINOL, multiple step anneals may be required to form the looped knuckle  585  configuration, where additional bending of the tab  585  can be accomplished iteratively so as to avoid exceeding the strain limitations of NITINOL. Alternatively, the tabs  585  can be continuously stressed during the anneal so as to slowly form the looped configuration without exceeding the strain limitations. 
       FIG. 25A-25C  are perspective views depicting additional exemplary embodiments of the valve support structure  32  having hinge  52  formed with interlocking mechanisms.  FIG. 25A  depicts an exemplary embodiment where each panel  36  includes multiple hinge apertures  591 , each configured to interface with a ring-like member  592 . Each ring-like member  592  can be separate or one continuous helical coil  593  can be threaded through the hinge apertures  591 , such as depicted here. 
       FIGS. 25B-25C  depict another exemplary embodiment where each panel  36  includes multiple hinge apertures  591 .  FIG. 25B  depicts a portion of the valve support structure  32  viewed from outside the structure  32 , while  FIG. 25C  depicts a portion of the valve support structure  32  viewed from within the generally cylindrical structure  32 . Here, a fingered hinge body  594  having multiple curved finger-like members  595  are threaded through the multiple hinge apertures  591  to form the hinge  52 . 
       FIGS. 26A-26B  depict additional exemplary embodiment of the valve support structure  32  having a native leaflet control member  626 . Native leaflet control member  626  is preferably configured to control the location of the native valve leaflet to prevent the leaflet from interfering with the implantation of the valve  30  or with the operation of valve  30 . Also, the native valve leaflet control member can be configured to prevent any portion of the native valve, which may be calcified or otherwise diseased, from breaking free and entering the bloodstream. 
       FIG. 26A  is a perspective view depicting an exemplary embodiment of the valve support structure  32  where the native leaflet control member  626  is a curved protrusion configured to hold the native leaflet in the open position against the vessel wall. The control member  626  is preferably biased towards the position depicted here, but can be deflectable inwards towards the support structure  32  so as not to create a path for blood flow between the valve support structure  32  and the vessel wall. The native valve leaflets typically reside adjacent to a depression in the vessel wall. The native leaflet control member  626  can be configured, if desired, to deflect the native valve leaflets into this depression, reducing the risk that the deflection of control members  626  will create a path for blood to flow around the valve support structure  32 .  FIG. 26B  is a perspective view depicting another exemplary embodiment where the control member  626  extends over the semi-circular aperture  40 . In this embodiment, several additional deflectable pointed control members  627  are included to substantially pin the native leaflet tissue in place. 
     The preferred embodiments of the inventions that are the subject of this application are described above in detail for the purpose of setting forth a complete disclosure and for the sake of explanation and clarity. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure. Such alternatives, additions, modifications, and improvements may be made without departing from the scope of the present inventions, which is defined by the claims.