Abstract:
This invention relates to the design and function of a compressible valve replacement prosthesis which can be deployed into a beating heart without extracorporeal circulation using a transcatheter delivery system. The design as discussed focuses on the deployment of a device via a minimally invasive fashion and by way of example considers a minimally invasive surgical procedure preferably utilizing the intercostal or subxyphoid space for valve introduction. In order to accomplish this, the valve is formed in such a manner that it can be compressed to fit within a delivery system and secondarily ejected from the delivery system into the annulus of a target valve such as a mitral valve or tricuspid valve.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/425,712, filed Mar. 31, 2012, entitled “Device and System for Transcatheter Mitral Valve Replacement,” which is a continuation of U.S. patent application Ser. No. 12/963,596, filed Dec. 8, 2010, entitled “Device and System for Transcatheter Mitral Valve Replacement,” which claims priority to U.S. Provisional Application Ser. No. 61/267,739, filed Dec. 8, 2009, each of the disclosures of which is incorporated herein by reference in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    No federal government funds were used in researching or developing this invention. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       SEQUENCE LISTING INCLUDED AND INCORPORATED BY REFERENCE HEREIN 
       [0004]    Not applicable. 
       BACKGROUND 
       [0005]    1. Field of the Invention 
         [0006]    This invention relates to a transcatheter mitral valve replacement and a delivery system therefor. 
         [0007]    2. Background of the Invention 
         [0008]    The current state of knowledge is as follows. 
         [0009]    Valvular heart disease and specifically aortic and mitral valve disease is a significant health issue in the US. Annually approximately 90,000 valve replacements are conducted in the US. Traditional valve replacement surgery, the orthotopic replacement of a heart valve, is an “open heart” surgical procedure. Briefly, the procedure necessitates surgical opening of the thorax, the initiation of extra-corporeal circulation with a heart-lung machine, stopping and opening the heart, excision and replacement of the diseased valve, and re-starting of the heart. While valve replacement surgery typically carries a 1-4% mortality risk in otherwise healthy persons, a significantly higher morbidity is associated to the procedure largely due to the necessity for extra-corporeal circulation. Further, open heart surgery is often poorly tolerated in elderly patients. 
         [0010]    Thus if the extra-corporeal component of the procedure could be eliminated, morbidities and cost of valve replacement therapies would be significantly reduced. 
         [0011]    While replacement of the aortic valve in a transcatheter manner is the subject of intense investigation, lesser attention has been focused on the mitral valve. This is in part reflective of the greater level of complexity associated to the native mitral valve apparatus and thus a greater level of difficulty with regards to inserting and anchoring the replacement prosthesis. 
         [0012]    Several designs for catheter-deployed (transcatheter) aortic valve replacement are under various stages of development. The Edwards SAPIEN transcatheter heart valve is currently undergoing clinical trial in patients with calcific aortic valve disease who are considered high-risk for conventional open-heart valve surgery. This valve is deployable via a retrograde transarterial (transfemoral) approach or an antegrade transapical (transventricular) approach. A key aspect of the Edwards SAPIEN and other transcatheter aortic valve replacement designs is their dependence on lateral fixation (e.g. tines) that engages the valve tissues as the primary anchoring mechanism. Such a design basically relies on circumferential friction around the valve housing or stent to prevent dislodgement during the cardiac cycle. This anchoring mechanism is facilitated by, and may somewhat depend on, a calcified aortic valve annulus. This design also requires that the valve housing or stent have a certain degree of rigidity. 
         [0013]    At least one transcatheter mitral valve design is currently in development. The Endovalve uses a folding tripod-like design that delivers a tri-leaflet bioprosthetic valve. It is designed to be deployed from a minimally invasive transatrial approach, and could eventually be adapted to a transvenous atrial septotomy delivery. This design uses “proprietary gripping features” designed to engage the valve annulus and leaflets tissues. Thus the anchoring mechanism of this device is essentially equivalent to that used by transcatheter aortic valve replacement designs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    The present invention relates to the design and function of a compressible prosthetic heart valve replacement which can be deployed into a closed beating heart using a transcatheter delivery system. The design as discussed focuses on the deployment of a device via a minimally invasive fashion and by way of example considers a minimally invasive surgical procedure utilizing the intercostal or subxyphoid space for valve introduction. In order to accomplish this, the valve is formed in such a manner that it can be compressed to fit within a delivery system and secondarily ejected from the delivery system into the target location, for example the mitral or tricuspid valve annulus. 
         [0015]    In a preferred embodiment, there is provided a prosthetic mitral valve containing a cuff which locally contours to the mitral annulus. 
         [0016]    In another preferred embodiment, there is provided a prosthetic heart valve with a cuff that has a tissue or synthetic covering. 
         [0017]    In another preferred embodiment, there is provided a prosthetic heart valve with a cuff that has articulating wire loops of various lengths. 
         [0018]    In another preferred embodiment, there is provided a prosthetic heart valve containing at least one elastic tether to provide compliance during the physiologic movement or conformational changes associated with heart contraction. 
         [0019]    In another preferred embodiment, there is provided a prosthetic heart valve having a stent body and cuff that are made from a superelastic metal. 
         [0020]    In another preferred embodiment, there is provided a prosthetic heart valve having a stent body and cuff that are made from a superelastic metal that is laser cut with predetermined shapes to facilitate collapsing into the catheter delivery system. 
         [0021]    In another preferred embodiment, there is provided a prosthetic heart valve having a stent body constructed from ductile metal, for example stainless steel, so as to require a balloon for expansion once located at the annulus, but capable of deformation without fracture. 
         [0022]    In another preferred embodiment, there is provided a prosthetic heart valve constructed from superelastic wire made from a shape memory alloy such as nickel-titanium alloy (Naval Ordinance Lab) Nitinol™. 
         [0023]    In another preferred embodiment, there is provided a laser cut prosthetic heart valve containing tethers for anchoring. 
         [0024]    In another preferred embodiment, there is provided a valve constructed from wire containing tethers for anchoring. 
         [0025]    In another preferred embodiment, there is provided a valve containing tether which are used to position the valve cuff into the mitral annulus to prevent perivalvular leak. 
         [0026]    In another preferred embodiment, there are tethers that are bioabsorbable and provide temporary anchoring until biological fixation of the prosthesis occurs. Biological fixation consisting of fibrous adhesions between the leaflet tissues and prosthesis or compression on the prosthesis by reversal of heart dilation, or both. 
         [0027]    In another preferred embodiment, there is provided a prosthetic heart valve constructed from wire or laser-formed demonstrating a compliant body and cuff such that the two components accommodate the movement of the heart throughout the cardiac cycle. 
         [0028]    In another preferred embodiment, there is provided a cuff for a prosthetic heart valve, said cuff being covered with tissue. 
         [0029]    In another preferred embodiment, there is provided a cuff for a prosthetic heart valve, said cuff being covered with a synthetic polymer selected from expandable poly-tetrafluoroethylene (ePTFE) or polyester. 
         [0030]    In another preferred embodiment, there is provided a prosthetic heart valve that has leaflet material constructed from a material selected from the group consisting of polyurethane, polytetrafluoroethylene, pericardium, and small intestine submucosa. 
         [0031]    In another preferred embodiment, there is provided a prosthetic heart valve having surfaces that are treated with anticoagulant. 
         [0032]    In another preferred embodiment, there is provided a prosthetic heart valve having a cuff and containing anchoring tethers which are attached to the cuff. 
         [0033]    In another preferred embodiment, there is provided a prosthetic heart valve having a cuff and containing anchoring tethers which are attached to the cuff and at both commissural tips. 
         [0034]    In another preferred embodiment, there is provided a prosthetic heart valve having a cuff where the cuff attachment relative to the body is within the angles of about 60 degrees to about 150 degrees. 
         [0035]    In another preferred embodiment, there is provided a prosthetic heart valve containing a combination of tethers and barbs useful for anchoring the device into the mitral annulus. 
         [0036]    In a preferred embodiment, there is provided a prosthetic heart valve which comprises an expandable tubular stent having a cuff and an expandable internal leaflet assembly, said leaflet assembly may or may not have a structural wire support, wherein said cuff is comprised of wire covered with stabilized tissue, and wherein said leaflet assembly is disposed within the stent and is comprised of stabilized tissue in the form of leaflets. 
         [0037]    In another embodiment, there is provided a feature wherein the wire of the cuff is formed as a series of radially extending loops of equal or variable length. 
         [0038]    In another embodiment, there is provided a feature wherein the cuff extends laterally beyond the expanded tubular stent according to a ratio of the relationship between the height of the expanded deployed stent (h) and the lateral distance that the cuff extends onto the tissue (1). Preferably, the h/1 ratio can range from 1:10 to 10:1, and more preferably includes without limitation 1:3, 1:2, 1:1, 2:1, and fractional ranges there between such as 1.25:2.0, 1.5:2.0, and so forth. It is contemplated in one non-limiting example that the cuff can extend laterally (1) between about 3 and about 30 millimeters. 
         [0039]    In another embodiment, there is provided a feature wherein the tubular stent has a first end and a second end, wherein the cuff is formed from the stent itself, or in the alternative is formed separately and wherein the cuff is located at the first end of the stent, and the second end of the tubular stent has a plurality of tether attachment structures. 
         [0040]    In another embodiment, there is provided a feature further comprising a plurality of tethers for anchoring the prosthetic heart valve to tissue and/or for positioning the prosthetic heart valve. 
         [0041]    In another embodiment, there is provided a feature further comprising an epicardial tether securing device, wherein the tethers extend between about 3 and about 8 cm in length, and are fastened to an epicardial tether securing device. 
         [0042]    In another embodiment, there is provided a catheter delivery system for delivery of a prosthetic heart valve which comprises a delivery catheter having the prosthetic heart valve disposed therein, and an obturator for expelling the prosthetic heart valve. 
         [0043]    In another embodiment, there is provided an assembly kit for preparing the catheter delivery system which comprises a compression funnel, an introducer, a wire snare, an obturator, a delivery catheter, and a prosthetic heart valve, wherein the compression funnel has an aperture for attaching to the introducer, wherein said introducer is comprised of a tube having a diameter that fits within the diameter of the delivery catheter, wherein said obturator is comprised of a tube fitted with a handle at one end and a cap at the other end, wherein here said cap has an opening to allow the wire snare to travel therethrough, and said obturator has a diameter that fits within the diameter of the introducer, and wherein said prosthetic heart valve is compressible and fits within the delivery catheter. 
         [0044]    In another embodiment, there is provided a method of treating mitral regurgitation and/or tricuspid regurgitation in a patient, which comprises the step of surgically deploying the prosthetic heart valve into the annulus of the target valve structure, e.g. mitral valve annulus and tricuspid valve annulus of the patient. 
         [0045]    In another embodiment, there is provided a feature wherein the prosthetic heart valve is deployed by directly accessing the heart through an intercostal space, using an apical approach to enter the left (or right) ventricle, and deploying the prosthetic heart valve into the valvular annulus using the catheter delivery system. 
         [0046]    In another embodiment, there is provided a feature wherein the prosthetic heart valve is deployed by directly accessing the heart through a thoracotomy, sternotomy, or minimally-invasive thoracic, thorascopic, or transdiaphragmatic approach to enter the left (or right) ventricle, and deploying the prosthetic heart valve into the valvular annulus using the catheter delivery system. 
         [0047]    In another embodiment, there is provided a feature wherein the prosthetic heart valve is deployed by directly accessing the heart through the intercostal space, using a lateral approach to enter the left or right ventricle, and deploying the prosthetic heart valve into the valvular annulus using the catheter delivery system. 
         [0048]    In another embodiment, there is provided a feature wherein the prosthetic heart valve is deployed by accessing the left heart using either an antegrade-trans(atrial)septal (transvenous-trans(atrial)septal) approach or a retrograde (transarterial-transaortic) catheter approach to enter the left heart, and deploying the prosthetic heart valve into the mitral annulus using the catheter delivery system. 
         [0049]    In another embodiment, there is provided a feature wherein the prosthetic heart valve is deployed into the mitral annulus from a retrograde approach by accessing the left ventricle through the apex of the ventricular septum (transvenous-trans(ventricular)septal approach). 
         [0050]    In another embodiment, there is a feature wherein the prosthetic heart valve is deployed into the mitral position using a retrograde transventricular septal approach and the tethers are anchored into or on the right ventricular side of the ventricular septum. 
         [0051]    In another embodiment, there is provided a feature further comprising tethering the prosthetic heart valve to tissue within the left ventricle. 
         [0052]    In another embodiment, there is provided a feature wherein the prosthetic heart valve is tethered to the apex of the left ventricle using an epicardial tether securing device. In another embodiment, such device is fashioned as a pledget, button or similar article. 
         [0053]    In another embodiment, there is provided a retrieval method for quickly removing a prosthetic heart valve having one or more tethers from a patient using minimally invasive cardiac catheter techniques, which comprises the steps of, capturing the one or more tethers with a catheter having a snare attachment, guiding the captured tethers into a collapsible funnel attachment connected to the removal catheter, pulling the tethers to conform the prosthetic heart valve into a collapsed, compressed conformation, and pulling the now compressed prosthetic heart valve into the removal catheter for subsequent extraction. The retrieval method is contemplated for use for capturing the prosthetic heart valve as described herein or any suitable tethered, collapsible medical device. In a preferred embodiment, the method is used to extract a prosthetic heart valve from either the left or right ventricle. The method may be particularly useful to extract the prosthetic appliance during an aborted surgical deployment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0054]      FIG. 1  is a perspective view of one embodiment of a prosthetic valve according to the present invention. 
           [0055]      FIG. 2  A-D is a perspective exploded view of one embodiment of a prosthetic valve according to the present invention that does not use a structural wire support for the valve cusps/leaflets. 
           [0056]      FIG. 3  A-E is a perspective exploded view of one embodiment of a prosthetic valve according to the present invention that incorporates a structural wire support for the valve cusps/leaflets. 
           [0057]      FIG. 4  is a top view of an embodiment of a prosthetic valve according to the present invention and shows a two-leaflet structure. 
           [0058]      FIG. 5  is a side view from slightly below the horizontal plane of one embodiment of a prosthetic valve according to the present invention to show the bottom surface of the cuff.  FIG. 5  shows the tethers without the structural wire support for the leaflets. 
           [0059]      FIG. 6  is a top view from slightly above the horizontal plane of one embodiment of a prosthetic valve according to the present invention and shows the top surface of the cuff and structural wire support loops extending beyond the length of the stent. 
           [0060]      FIG. 7  is a view of one embodiment of a prosthetic valve according to the present invention showing that the cuff spindles may optionally have variable lengths and sizes. 
           [0061]      FIG. 8  is a view of one embodiment of a prosthetic valve according to the present invention showing that the cuff spindles may optionally have variable lengths and sizes. Here they are shown to create an elongated cuff. 
           [0062]      FIG. 9  is a top view of one embodiment of a prosthetic valve according to the present invention showing a three-leaflet structure. 
           [0063]      FIG. 10  A-C is a series of side views of one embodiment of a prosthetic valve according to the present invention illustrating that the cuff may be formed to have an original configuration whereby the cuffs disposition relative to the stent body has an acute, right, or obtuse angle. 
           [0064]      FIG. 11  is a side view of one embodiment of a prosthetic valve according to the present invention illustrating the use of a barb component to assist seating the prosthetic valve in the valvular annulus. 
           [0065]      FIG. 12  A-B is a pair of side views of one embodiment of a prosthetic valve according to the present invention illustrating the use of a barb component which is open but then closes upon or into the annular tissue when the stent body is expanded to assist seating the prosthetic valve in the valvular annulus. 
           [0066]      FIG. 13  is a side view of one embodiment of a prosthetic valve according to the present invention showing tethers attached to the cuff portion in addition to attachment on the stent body. 
           [0067]      FIG. 14  is a drawing of one embodiment of the delivery system equipment according to the present invention used to compress and deploy the prosthetic valve. 
           [0068]      FIG. 15  A-F is a series of drawings of one embodiment of the delivery system according to the present invention. 
           [0069]      FIG. 16  is a detailed sectional view of an embodiment of a delivery catheter, and one embodiment of a compressed prosthetic valve according to the present invention disposed within the delivery catheter. 
           [0070]      FIG. 17  is a cut-away view of a heart with a delivery catheter containing a prosthetic valve according to the present invention and accessing the heart using an apical approach.  FIG. 17  shows the delivery catheter advanced to through the mitral valve and into the left atrium for deployment of the prosthetic valve. 
           [0071]      FIG. 18  A-D is a series of views of the tip of one embodiment of a delivery catheter according to the present invention containing a pre-loaded prosthetic valve which is being pushed out of the delivery catheter, i.e. by an obturator, starting with (A) the valve completely within the catheter, (B) the cuff portion being in view, (C) the stent body following, and (D) the prosthetic valve with attached tethers for positioning and/or adjustment and/or securing the valve to tissue. 
           [0072]      FIG. 19  is a detailed sectional view of one embodiment of a prosthetic valve according to the present invention deployed within the annulus of the mitral valve of the heart and shows that it is anchored using (a) the atrial cuff and (b) the ventricular tethers connected to the apex, which are shown secured by a securing pledget. 
           [0073]      FIG. 20  is a detailed side-perspective view of one embodiment of a prosthetic valve according to the present invention deployed within the annulus of the mitral valve of the heart and anchored using (a) the atrial cuff and (b) the ventricular tethers connected to papillary muscles and/or ventricular wall and/or septum, which are each secured by one or more securing tissue anchors. 
           [0074]      FIG. 21  A-B is a pair of drawings showing one embodiment of a ventricular tether attachment according to the present invention.  FIG. 21  A is a detailed drawing of the flexible delivery catheter inserted into the left ventricular apex along with four sutures having partially installed apical-closure/tissue-buttressing material.  FIG. 21  B is a detailed drawing of the anchoring system of the prosthetic valve in which the ventricular tethers are shown treaded through the left ventricle apex and through a partially installed pledget; also shown are fully installed apical-closure material. 
           [0075]      FIG. 22  A-B is a pair of drawings of the lateral deployment of one embodiment of a prosthetic valve according to the present invention.  FIG. 22B  is a detail view of an illustration of the prosthetic valve seated within the mitral annulus and tethered to the papillary muscles of the left ventricle. 
           [0076]      FIG. 23  is a cut-away view of a heart with a delivery catheter containing a prosthetic valve according to the present invention and accessing the right ventricle of the heart using an apical approach.  FIG. 23  shows the delivery catheter advanced through to the tricuspid valve and into the right atrium for deployment of the prosthetic valve. 
           [0077]      FIG. 24  A-B shows an embodiment of a prosthetic valve having a ring or halo feature.  FIG. 24A  is a bottom view from slightly above the horizontal plane of one embodiment of a prosthetic valve according to the present invention to show the bottom surface of the cuff and the halo feature.  FIG. 24  B is a top view from slightly above the horizontal plane of one embodiment of a prosthetic valve according to the present invention to show the top surface of the cuff. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0078]    The present invention provides in one embodiment a prosthetic heart valve that comprises a self-expanding valve assembly that is anchored within the mitral valve of the heart using an integral cuff to anchor the valve and using one or more tethers anchored to the heart. It is contemplated as within the scope of the invention to provide a prosthetic heart valve having as an anchoring system both an integral cuff or collar and one or more tethers for tissue anchoring. 
         [0079]    The prosthetic heart valve comprises a self-expanding tubular stent having a cuff at one end and tether loops for attaching tethers at the other end, and disposed within the tubular stent is a leaflet assembly that contains the valve leaflets, the valve leaflets being formed from stabilized tissue or other suitable biological or synthetic material. In one embodiment, the leaflet assembly comprises a wire form where a formed wire structure is used in conjunction with stabilized tissue to create a leaflet support structure which can have anywhere from 1, 2, 3 or 4 leaflets, or valve cusps disposed therein. In another embodiment, the leaflet assembly is wireless and uses only the stabilized tissue and stent body to provide the leaflet support structure, without using wire, and which can also have anywhere from 1, 2, 3 or 4 leaflets, or valve cusps disposed therein. 
       Functions of the Cuff 
       [0080]    The cuff functions in a variety of ways. The first function of the cuff is to inhibit perivalvular leak/regurgitation of blood around the prosthesis. By flexing and sealing across the irregular contours of the annulus and atrium, leaking is minimized and/or prevented. 
         [0081]    The second function of the cuff is to provide an adjustable and/or compliant bio-prosthetic valve. The heart and its structures undergo complex conformational changes during the cardiac cycle. For example, the mitral valve annulus has a complex geometric shape known as a hyperbolic parabloid much like a saddle, with the horn being anterior, the seat back being posterior, and the left and right valleys located medially and laterally. Beyond this complexity, the area of the mitral annulus changes over the course of the cardiac cycle. Further, the geometry of the tricuspid valve and tricuspid annulus continues to be a topic of research, posing its own particular problems. Accordingly, compliance is a very important but unfortunately often overlooked requirement of cardiac devices. Compliance here refers to the ability of the valve to maintain structural position and integrity during the cardiac cycle. Compliance with the motion of the heart is a particularly important feature, especially the ability to provide localized compliance where the underlying surfaces are acting differently from the adjacent surfaces. This ability to vary throughout the cardiac cycle allows the valve to remain seated and properly deployed in a manner not heretofore provided. 
         [0082]    Additionally, compliance may be achieved through the use of the tethers where the tethers are preferably made from an elastic material. Tether-based compliance may be used alone, or in combination with the cuff-based compliance. 
         [0083]    The third function of the cuff valve is to provide a valve that, during surgery, is able to be seated and be able to contour to the irregular surfaces of the atrium. The use of independent tethers allows for side to side fitting of the valve within the annulus. For example, where three tethers are used, they are located circumferentially about 120 degrees relative to each other which allows the surgeon to observe whether or where perivalvular leaking might be occurring and to pull on one side or the other to create localized pressure and reduce or eliminate the leaking. 
         [0084]    The fourth function of the cuff is to counter the forces that act to displace the prosthesis toward/into the ventricle (i.e. atrial pressure and flow-generated shear stress) during ventricular filling. 
         [0085]    Additional features of the cuff include that it functions to strengthen the leaflet assembly/stent combination by providing additional structure. Further, during deployment, the cuff functions to guide the entire structure, the prosthetic valve, into place at the mitral annulus during deployment and to keep the valve in place once it is deployed. 
       Cuff Structure 
       [0086]    The cuff is a substantially flat plate that projects beyond the diameter of the tubular stent to form a rim or border. As used herein, the term cuff, flange, collar, bonnet, apron, or skirting are considered to be functionally equivalent. When the tubular stent is pulled through the mitral valve aperture, the mitral annulus, by the tether loops in the direction of the left ventricle, the cuff acts as a collar to stop the tubular stent from traveling any further through the mitral valve aperture. The entire prosthetic valve is held by longitudinal forces between the cuff which is seated in the left atrium and mitral annulus, and the ventricular tethers attached to the left ventricle. 
         [0087]    The cuff is formed from a stiff, flexible shape-memory material such as the nickel-titanium alloy material Nitinol™ wire that is covered by stabilized tissue or other suitable biocompatible or synthetic material. In one embodiment, the cuff wire form is constructed from independent loops of wire that create lobes or segments extending axially around the circumference of the bend or seam where the cuff transitions to the tubular stent (in an integral cuff) or where the cuff is attached to the stent (where they are separate, but joined components). 
         [0088]    Once covered by stabilized tissue or material, the loops provide the cuff the ability to travel up and down, to articulate, along the longitudinal axis that runs through the center of the tubular stent. In other words, the individual spindles or loops can independently move up and down, and can spring back to their original position due to the relative stiffness of the wire. The tissue or material that covers the cuff wire has a certain modulus of elasticity such that, when attached to the wire of the cuff, is able to allow the wire spindles to move. This flexibility gives the cuff, upon being deployed within a patient&#39;s heart, the ability to conform to the anatomical shape necessary for a particular application. In the example of a prosthetic mitral valve, the cuff is able to conform to the irregularities of the left atrium and shape of the mitral annulus, and to provide a tight seal against the atrial tissue adjacent the mitral annulus and the tissue within the mitral annulus. As stated previously, this feature importantly provides a degree of flexibility in sizing a mitral valve and prevents blood from leaking around the implanted prosthetic heart valve. 
         [0089]    An additional important aspect of the cuff dimension and shape is that, when fully seated and secured, the edge of the cuff preferably should not be oriented laterally into the atrial wall such that it can produce a penetrating or cutting action on the atrial wall. 
         [0090]    In one preferred embodiment, the wire spindles of the cuff are substantially uniform in shape and size. In another preferred embodiment of the present invention, each loop or spindle may be of varying shapes and sizes. In this example, it is contemplated that the loops may form a pattern of alternating large and small loops, depending on where the valve is being deployed. In the case of a prosthetic mitral valve, pre-operative imaging may allow for customizing the structure of the cuff depending on a particular patient&#39;s anatomical geometry in the vicinity of the mitral annulus. 
         [0091]    The cuff wire form is constructed so as to provide sufficient structural integrity to withstand the intracardiac forces without collapsing. The cuff wire form is preferably constructed of a superelastic metal, such as Nitinol™ ® and is capable of maintaining its function as a scaling collar for the tubular stent while under longitudinal forces that might cause a structural deformation or valve displacement. It is contemplated as within the scope of the invention to optionally use other shape memory alloys such as Cu—Zn—Al—Ni alloys, and Cu—Al—Ni alloys. The heart is known to generate an average left atrial pressure between about 8 and 30 mm Hg (about 0.15 to 0.6 psi). This left atrial filling pressure is the expected approximate pressure that would be exerted in the direction of the left ventricle when the prosthesis is open against the outer face of the cuff as an anchoring force holding the cuff against the atrial tissue that is adjacent the mitral valve. The cuff counteracts this longitudinal pressure against the prosthesis in the direction of the left ventricle to keep the valve from being displaced or slipping into the ventricle. In contrast, left ventricular systolic pressure, normally about 120 mm Hg, exerts a force on the closed prosthesis in the direction of the left atrium. The tethers counteract this force and are used to maintain the valve position and withstand the ventricular force during ventricular contraction or systole. Accordingly, the cuff has sufficient structural integrity to provide the necessary tension against the tethers without being dislodged and pulled into the left ventricle. After a period of time, changes in the geometry of the heart and/or fibrous adhesion between prosthesis and surrounding cardiac tissues may assist or replace the function of the ventricular tethers in resisting longitudinal forces on the valve prosthesis during ventricular contraction. 
       Stent Structure 
       [0092]    Preferably, superelastic metal wire, such as Nitinol™ wire, is used for the stent, for the inner wire-based leaflet assembly that is disposed within the stent, and for the cuffwire form. As stated, it is contemplated as within the scope of the invention to optionally use other shape memory alloys such as Cu—Zn—Al—Ni alloys, and Cu—Al—Ni alloys. It is contemplated that the stent may be constructed as a braided stent or as a laser cut stent. Such stents are available from any number of commercial manufacturers, such as Pulse Systems. Laser cut stents are preferably made from Nickel-Titanium (Nitinol™), but also without limitation made from stainless steel, cobalt chromium, titanium, and other functionally equivalent metals and alloys, or Pulse Systems braided stent that is shape-set by heat treating on a fixture or mandrel. 
         [0093]    One key aspect of the stent design is that it be compressible and when released have the stated property that it return to its original (uncompressed) shape. This requirement limits the potential material selections to metals and plastics that have shape memory properties. With regards to metals, Nitinol has been found to be especially useful since it can be processed to be austhenitic, martensitic or super elastic. Martensitic and super elastic alloys can be processed to demonstrate the required compression features. 
       Laser Cut Stent 
       [0094]    One possible construction of the stent envisions the laser cutting of a thin, isodiametric Nitinol tube. The laser cuts form regular cutouts in the thin Nitinol tube. Secondarily the tube is placed on a mold of the desired shape, heated to the Martensitic temperature and quenched. The treatment of the stent in this manner will form a stent or stent/cuff that has shape memory properties and will readily revert to the memory shape at the calibrated temperature. 
       Braided Wire Stent 
       [0095]    A stent can be constructed utilizing simple braiding techniques. Using a Nitinol wire for example a 0.012″ wire—and a simple braiding fixture, the wire is wound on the braiding fixture in a simple over/under braiding pattern until an isodiametric tube is formed from a single wire. The two loose ends of the wire are coupled using a stainless steel or Nitinol coupling tube into which the loose ends are placed and crimped. Angular braids of approximately 60 degrees have been found to be particularly useful. Secondarily, the braided stent is placed on a shaping fixture and placed in a muffle furnace at a specified temperature to set the stent to the desired shape and to develop the martensitic or super elastic properties desired. 
         [0096]    The stent as envisioned in one preferred embodiment is designed such that the ventricular aspect of the stent comes to 2-5 points onto which anchoring sutures are affixed. The anchoring sutures (tethers) will traverse the ventricle and ultimately be anchored to the epicardial surface of the heart approximately at the level of the apex. The tethers when installed under slight tension will serve to hold the valve in place, i.e. inhibit paravalvular leakage during systole. 
       Leaflet and Assembly Structure 
       [0097]    The valve leaflets are held by, or within, a leaflet assembly. In one preferred embodiment of the invention, the leaflet assembly comprises a leaflet wire support structure to which the leaflets are attached and the entire leaflet assembly is housed within the stent body. In this embodiment, the assembly is constructed of wire and stabilized tissue to form a suitable platform for attaching the leaflets. In this aspect, the wire and stabilized tissue allow for the leaflet structure to be compressed when the prosthetic valve is compressed within the deployment catheter, and to spring open into the proper functional shape when the prosthetic valve is opened during deployment. In this embodiment, the leaflet assembly may optionally be attached to and housed within a separate cylindrical liner made of stabilized tissue or material, and the liner is then attached to line the interior of the stent body. 
         [0098]    In this embodiment, the leaflet wire support structure is constructed to have a collapsible/expandable geometry. In a preferred embodiment, the structure is a single piece of wire. The wire form is, in one embodiment, constructed from a shape memory alloy such as Nitinol. The structure may optionally be made of a plurality of wires, including between 2 to 10 wires. Further, the geometry of the wire form is without limitation, and may optionally be a series of parabolic inverted collapsible arches to mimic the saddle-like shape of the native annulus when the leaflets are attached. Alternatively, it may optionally be constructed as collapsible concentric rings, or other similar geometric forms that are able to collapse/compress which is followed by an expansion to its functional shape. In certain preferred embodiments, there may be 2, 3 or 4 arches. In another embodiment, closed circular or ellipsoid structure designs are contemplated. In another embodiment, the wire form may be an umbrella-type structure, or other similar unfold-and-lock-open designs. A preferred embodiment utilizes super elastic Nitinol wire approximately 0.015″ in diameter. In this embodiment, the wire is wound around a shaping fixture in such a manner that 2-3 commissural posts are formed. The fixture containing the wrapped wire is placed in a muffle furnace at a pre-determined temperature to set the shape of the wire form and to impart its super elastic properties. Secondarily, the loose ends of the wire form are joined with a stainless steel or Nitinol tube and crimped to form a continuous shape. In another preferred embodiment, the commissural posts of the wire-form are adjoined at their tips by a circular connecting ring, or halo, whose purpose is to minimize inward deflection of the post(s). 
         [0099]    In another preferred embodiment, the leaflet assembly is constructed solely of stabilized tissue or other suitable material without a separate wire support structure. The leaflet assembly in this embodiment is also disposed within the lumen of the stent and is attached to the stent to provide a sealed joint between the leaflet assembly and the inner wall of the stent. By definition, it is contemplated within the scope of the invention that any structure made from stabilized tissue and/or wire(s) related to supporting the leaflets within the stent constitute a leaflet assembly. In this embodiment, stabilized tissue or suitable material may also optionally be used as a liner for the inner wall of the stent and is considered part of the leaflet assembly. 
         [0100]    Liner tissue or biocompatible material may be processed to have the same or different mechanical qualities, e.g. thickness, durability, etc. from the leaflet tissue. 
         [0000]    Deployment within the Valvular Annulus 
         [0101]    The prosthetic heart valve is, in one embodiment, apically delivered through the apex of the left ventricle of the heart using a catheter system. In one aspect of the apical delivery, the catheter system accesses the heart and pericardial space by intercostal delivery. In another delivery approach, the catheter system delivers the prosthetic heart valve using either an antegrade or retrograde delivery approach using a flexible catheter system, and without requiring the rigid tube system commonly used. In another embodiment, the catheter system accesses the heart via a trans-septal approach. 
         [0102]    In one non-limiting preferred embodiment, the stent body extends into the ventricle about to the edge of the open mitral valve leaflets (approximately 25% of the distance between the annulus and the ventricular apex). The open native leaflets lay against the outside stent wall and parallel to the long axis of the stent (i.e. the stent holds the native mitral valve open). 
         [0103]    In one non-limiting preferred embodiment, the diameter should approximately match the diameter of the mitral annulus. Optionally, the valve may be positioned to sit in the mitral annulus at a slight angle directed away from the aortic valve such that it is not obstructing flow through the aortic valve. Optionally, the outflow portion (bottom) of the stent should not be too close to the lateral wall of the ventricle or papillary muscle as this position may interfere with flow through the prosthesis. As these options relate to the tricuspid, the position of the tricuspid valve may be very similar to that of the mitral valve. 
         [0104]    In another embodiment, the prosthetic valve is sized and configured for use in areas other than the mitral annulus, including, without limitation, the tricuspid valve between the right atrium and right ventricle. Alternative embodiments may optionally include variations to the cuff structure to accommodate deployment to the pulmonary valve between the right ventricle and pulmonary artery, and the aortic valve between the left ventricle and the aorta. In one embodiment, the prosthetic valve is optionally used as a venous backflow valve for the venous system, including without limitation the vena cava, femoral, subclavian, pulmonary, hepatic, renal and cardiac. In this aspect, the cuff feature is utilized to provide additional protection against leaking. 
       Tethers 
       [0105]    In one preferred embodiment, there are tethers attached to the prosthetic heart valve that extend to one or more tissue anchor locations within the heart. In one preferred embodiment, the tethers extend downward through the left ventricle, exiting the left ventricle at the apex of the heart to be fastened on the epicardial surface outside of the heart. Similar anchoring is contemplated herein as it regards the tricuspid, or other valve structure requiring a prosthetic. There may be from 2 to 8 tethers which are preferably attached to the stent. 
         [0106]    In another preferred embodiment, the tethers may optionally be attached to the cuff to provide additional control over position, adjustment, and compliance. In this preferred embodiment, one or more tethers are optionally attached to the cuff, in addition to, or optionally, in place of, the tethers attached to the stent. By attaching to the cuff and/or the stent, an even higher degree of control over positioning, adjustment, and compliance is provided to the operator during deployment. 
         [0107]    During deployment, the operator is able to adjust or customize the tethers to the correct length for a particular patient&#39;s anatomy. The tethers also allow the operator to tighten the cuff onto the tissue around the valvular annulus by pulling the tethers, which creates a leak-free seal. 
         [0108]    In another preferred embodiment, the tethers are optionally anchored to other tissue locations depending on the particular application of the prosthetic heart valve. In the case of a mitral valve, or the tricuspid valve, there are optionally one or more tethers anchored to one or both papillary muscles, septum, and/or ventricular wall. 
         [0109]    The tethers, in conjunction with the cuff, provide for a compliant valve which has heretofore not been available. The tethers are made from surgical-grade materials such as biocompatible polymer suture material. Examples of such material include 2-0 exPFTE (polytetrafluoroethylene) or 2-0 polypropylene. In one embodiment the tethers are inelastic. It is also contemplated that one or more of the tethers may optionally be elastic to provide an even further degree of compliance of the valve during the cardiac cycle. Upon being drawn to and through the apex of the heart, the tethers may be fastened by a suitable mechanism such as tying off to a pledget or similar adjustable button-type anchoring device to inhibit retraction of the tether back into the ventricle. It is also contemplated that the tethers might be bioresorbable/bioabsorbable and thereby provide temporary fixation until other types of fixation take hold such a biological fibrous adhesion between the tissues and prosthesis and/or radial compression from a reduction in the degree of heart chamber dilation. 
         [0110]    Further, it is contemplated that the prosthetic heart valve may optionally be deployed with a combination of installation tethers and permanent tethers, attached to either the stent or cuff, or both, the installation tethers being removed after the valve is successfully deployed. It is also contemplated that combinations of inelastic and elastic tethers may optionally be used for deployment and to provide structural and positional compliance of the valve during the cardiac cycle. 
       Pledget 
       [0111]    In one embodiment, to control the potential tearing of tissue at the apical entry point of the delivery system, a circular, semi-circular, or multi-part pledget is employed. The pledget may be constructed from a semi-rigid material such as PFTE felt. Prior to puncturing of the apex by the delivery system, the felt is firmly attached to the heart such that the apex is centrally located. Secondarily, the delivery system is introduced through the central area, or orifice as it may be, of the pledget. Positioned and attached in this manner, the pledget acts to control any potential tearing at the apex. 
       Tines/Barbs 
       [0112]    In another embodiment the valve can be seated within the valvular annulus through the use of tines or barbs. These may be used in conjunction with, or in place of one or more tethers. The tines or barbs are located to provide attachment to adjacent tissue. In one preferred embodiment, the tines are optionally circumferentially located around the bend/transition area between the stent and the cuff. Such tines are forced into the annular tissue by mechanical means such as using a balloon catheter. In one non-limiting embodiment, the tines may optionally be semi-circular hooks that upon expansion of the stent body, pierce, rotate into, and hold annular tissue securely. 
       Stabilized Tissue or Biocompatible Material 
       [0113]    In one embodiment, it is contemplated that multiple types of tissue and biocompatible material may be used to cover the cuff, to form the valve leaflets, to form a wireless leaflet assembly, and/or to line both the inner and/or outer lateral walls of the stent. As stated previously, the leaflet component may be constructed solely from stabilized tissue, without using wire, to create a leaflet assembly and valve leaflets. In this aspect, the tissue-only leaflet component may be attached to the stent with or without the use of the wire form. In a preferred embodiment, there can be anywhere from 1, 2, 3 or 4 leaflets, or valve cusps. 
         [0114]    It is contemplated that the tissue may be used to cover the inside of the stent body, the outside of the stent body, and the top and/or bottom side of the cuff wire form, or any combination thereof. 
         [0115]    In one preferred embodiment, the tissue used herein is optionally a biological tissue and may be a chemically stabilized valve of an animal, such as a pig. In another preferred embodiment, the biological tissue is used to make leaflets that are sewn or attached to a metal frame. This tissue is chemically stabilized pericardial tissue of an animal, such as a cow (bovine pericardium) or sheep (ovine pericardium) or pig (porcine pericardium) or horse (equine pericardium). 
         [0116]    Preferably, the tissue is bovine pericardial tissue. Examples of suitable tissue include that used in the products Duraguard®, Peri-Guard®, and Vascu-Guard®, all products currently used in surgical procedures, and which are marketed as being harvested generally from cattle less than 30 months old. Other patents and publications disclose the surgical use of harvested, biocompatible animal thin tissues suitable herein as biocompatible “jackets” or sleeves for implantable stents, including for example, U.S. Pat. No. 5,554,185 to Block, U.S. Pat. No. 7,108,717 to Design &amp; Performance-Cyprus Limited disclosing a covered stent assembly, U.S. Pat. No. 6,440,164 to Scimed Life Systems, Inc. disclosing a bioprosthetic valve for implantation, and U.S. Pat. No. 5,336,616 to LifeCell Corporation discloses a cellular collagen-based tissue matrix for transplantation. 
         [0117]    In one preferred embodiment, the valve leaflets may optionally be made from a synthetic material such as a polyurethane or polytetrafluoroethylene. Where a thin, durable synthetic material is contemplated, e.g. for covering the cuff, synthetic polymer materials such expanded polytetrafluoroethylene or polyester may optionally be used. Other suitable materials may optionally include thermoplastic polycarbonate urethane, polyether urethane, segmented polyether urethane, silicone polyether urethane, siliconepolycarbonate urethane, and ultra-high molecular weight polyethylene. Additional biocompatible polymers may optionally include polyolefins, elastomers, polyethyleneglycols, polyethersulphones, polysulphones, polyvinylpyrrolidones, polyvinylchlorides, other fluoropolymers, silicone polyesters, siloxane polymers and/or oligomers, and/or polylactones, and block co-polymers using the same. 
         [0118]    In another embodiment, the valve leaflets may optionally have a surface that has been treated with (or reacted with) an anti-coagulant, such as, without limitation, immobilized heparin. Such currently available heparinized polymers are known and available to a person of ordinary skill in the art. 
         [0119]    Alternatively, the valve leaflets may optionally be made from pericardial tissue or small intestine submucosal tissue. 
       Manufacture of Ultra-Thin Stabilized Tissue 
       [0120]    In a preferred embodiment, ultra-thin vapor-cross linked stabilized bioprosthetic or implant tissue material is contemplated. Tissue having a 0.003′ (0.0762 mm) to about 0.010″ (0.254 mm) may be made using a process comprising the steps of: (a) vapor cross-linking a pre-digested compressed tissue specimen by exposing the tissue specimen to a vapor of a cross-linking agent selected from the group consisting of aldehydes, epoxides, isocyanates, carbodiimides, isothiocyanates, glycidalethers, and acyl azides; and (b) chemically cross-linking the vapor-cross-linked tissue specimen by exposing the vapor-crosslinked tissue specimen to an aqueous crosslinking bath for a predetermined time, such cross linking bath containing a liquid phase of a crosslinking agent selected from the group consisting of aldehydes, epoxides, isocyanates, carbodiimides, isothiocyanates, glycidalethers, and acyl azides. Such tissue may be porcine, ovine, equine or bovine in origin and preferably the initial material is taken from a bovine animal 30 days old or less, although tissue from older animals is contemplated as within the scope of the invention. In one preferred embodiment, the tissue specimen is subjected to chemical de-hydration/compression and mechanical compression before cross-linking. 
         [0121]    Pre-digestion is provided by digesting a harvested, cleaned pericardial tissue in a solution containing a surfactant, such as 1% sodium laurel sulfate. The chemical dehydration/compression step comprises subjecting the tissue specimen to hyperosmotic salt solution. And, the mechanical compression may be performed by subjecting the tissue specimen to a roller apparatus capable of compressing the tissue specimen to a thickness ranging from about 0.003′ (0.0762 mm) to about 0.010″ (0.254 mm). 
         [0122]    The animal collagen tissue specimen is then chemically cross-linked first by exposing the tissue to formaldehyde vapor for approximately 10 minutes, and second by immersing the tissue in a glutaraldehyde solution for two consecutive sessions of approximately 24 hours each. 
       Retrieval System 
       [0123]    In another embodiment, a retrieval system is contemplated for quickly removing the prosthetic valve during an aborted surgical deployment using minimally invasive cardiac catheter techniques. In this embodiment, the tethers would be captured by a catheter having a snare attachment. Once the tethers were captured, an intra-ventricular funnel attachment would guide the prosthetic valve into a collapsed, compressed conformation by pulling on the tethers, thus pulling the compressed prosthetic valve into the removal catheter for subsequent extraction. 
         [0124]    To better assist understanding of the inventive subject matter, the following terms are given a more detailed definition. 
       DESCRIPTION OF FIGURES 
       [0125]    Referring now to the FIGURES,  FIG. 1  shows one embodiment of a prosthetic heart valve  110  according to the present invention, comprising tubular stent  112  having tether attachment structures  114  at one end and tubular stent  112  is attached to cuff  116  at the other end. Leaflet assembly  118  (not shown) is disposed within stent  112  and supports leaflets  120  (also not shown). Cuff  116  has independent articulating loops of wire  122  and covering  124 . 
         [0126]    As stated, tubular stent  112  may be an expandable laser cut stent or an expandable braided stent. Tubular stent  112  may be constructed of Martensitic or super clastic metal alloys. Tubular stent  112  may be compressed along its longitudinal axis and will fit into a catheter-based stent delivery system. When the tubular stent  112  is delivered to the location where it is to be installed, it is expelled from the catheter by an obturator and deposited at the site where it is to be deployed. 
         [0127]    Tubular stent  112  includes a plurality of tether attachments  114  upon which a tether (not shown) may be connected.  FIG. 1  shows an embodiment having three tether attachments which are integrated into the distal portion of the stent  112 . 
         [0128]    Leaflet assembly  118  is a separate but integrated structure that is disposed within the stent  112 . Leaflet assembly  118  functions to provide the structure upon which the valve leaflets or cusps  120  are located. Leaflet assembly  118  may be made entirely of stabilized tissue or it may be a combination wire and tissue structure. Where leaflet assembly  118  is composed entirely of tissue, it is contemplated that the leaflet assembly, leaflet support structure, and leaflets or cusps  120  are made from tissue. It is contemplated as within the scope of the invention that different qualities of stabilized tissue, i.e. thin or thick, structurally rigid or flexible as it may be, may be used for the different components of the cuff covering  124 , the stent covering, the leaflet assembly  118  and the leaflets  120 . Where leaflet assembly  118  is composed of wire and tissue, it contemplated that assembly or support(s), or both, may be made from wire, and the cusps  120  would necessarily be made from tissue. 
         [0129]    Prosthetic heart valve  110  also includes cuff  116 .  FIG. 1  shows cuff  116  formed from a cuff wire form  122  that is covered by, in one embodiment, stabilized tissue  124 . In one embodiment, the cuff wire form is an extension of the stent itself, where the stent has been heated and manipulated upon a form to create the extended spindles of the flat, collar plate of the cuff. In another embodiment, the cuff wire form  122  is made separate from the stent  112  and attached as a flat collar plate constructed to include an inner rim  130  and an outer rim  132 , with independent loops of wire  122  that create lobes or segments extending axially around the circumference of the inner rim, the joint  130  where the cuff  116  meets the tubular stent  112 . 
         [0130]    Referring now to  FIG. 2 , an exploded component view is provided that shows cuff covering  124  in  FIG. 2A . In  FIG. 2B , the wire cuff loops, or spindles,  122 , is illustrated along with stent body  112  and tether attachments  114 . The combination of the stabilized tissue of the cuff covering  124  and wire cuff spindles, make up a cuff structure and provide a semi-rigid form that assists in the sealing of the cuff against the atrial trabeculations and tissue within and adjacent to the mitral annulus. 
         [0131]    Referring to the stent body, it is contemplated as within the scope of the invention to include both laser cut stent technology and/or the braided stent technology. Where the cuff wire form  122  is merely an extension of a braided stent and forms a unitary stent-cuff construction, the spindles are formed by heating a Nitinol (IM) stent on a mold to create the proper extension and angle necessary to establish the cuff or collar portion. 
         [0132]    Where the stent is laser cut, the cuff wire form  122  may be manufactured as a unitary laser-cut stent-cuff construction. In this embodiment, the cuff wire form and the stent are laser cut within the same overall manufacturing process. Where the cuff wire form is made separate from the stent and attached as a flat collar plate, the cuff wire form and stent may be manufactured/laser cut separately and attached using laser weld or other similar technique to create a non-fatiguing elastic stent-cuff joint capable of maintaining elastic compliance while it is deployed. 
         [0133]    As noted, the rim may consist of an artificial transition point between the stent and the cuff where the stent has been heated to change the shape and angle of the topmost portion of the stent or the valve has been laser cut to create its overall wire form, or the rim may consist of a constructed transition point such as a laser welded joint for attaching two component parts. 
         [0134]    Once the cuff is covered by stabilized tissue  124 , the loops  122  provide the cuff  116  the ability to travel or flex up and down, along the longitudinal axis; longitudinal defined by the lengthwise axis of the stent. As stated, this flexibility or compliance provides the prosthetic heart valve, specifically the cuff, upon being deployed within a patient&#39;s heart, the ability to conform to the anatomical shape of the left atrium, maintain the conforming shape during the cardiac cycle, and provide a tight seal against the atrial tissue adjacent the mitral valve aperture. This feature reduces or removes the guesswork that often accompanies the pre-surgical sizing of a mitral valve. By providing a better fit, this necessarily prevents blood from leaking around the implanted prosthetic heart valve. 
         [0135]    The cuff tissue  126  is thin, durable, and may be attached to the top, bottom, or both sides of the cuff  116 . 
         [0136]    Referring now to  FIG. 2C  is a stent liner  128  made from tissue and that may optionally function to support the leaflets of the valve. This liner is contemplated as being made of tissue or biocompatible material as disclosed herein. The stent may also optionally have an inner stent liner and/or an outer (surface) stent liner.  FIG. 2D  is a perspective view of one embodiment of a two-piece structure made of leaflets  120 . In this embodiment, the leaflet structure is illustrated in a prosthetic heart valve having a mitral valve shape, a “saddle shape” that constitutes a hyperbolic paraboloid to afford one specific form of structural integrity. 
         [0137]    Referring now to the exploded view in  FIG. 3  A-E, the cuff covering  124  is shown in  FIG. 3A . The stent body  112  and cuff spindles  122  are shown in  FIG. 3B .  FIG. 3C  shows a stent liner  128  made from tissue and that may optionally function to support the leaflets of the valve.  FIG. 3D  is a perspective view of one embodiment of a two-piece structure made of leaflets  120 , and illustrated in a prosthetic heart valve having a mitral valve shape, a “saddle shape”. 
         [0138]      FIG. 3E  shows the use of a structural wire support  126  for the leaflets  120 . This leaflet structural wire support also provides spring-like tension to assist in the proper orientation of the leaflets once the prosthetic heart valve is expanded from a compressed stored shape to its final functional shape.  FIG. 3E  shows the three junctions  146  (commissural tips) and the three arched wires  148  (of this embodiment) of the leaflet structural wire support  126 . Leaflet wire form is preferably constructed as a single wire that is molded, twisted, and/or manipulated into the final shape. In another embodiment, the leaflet wire form is series of wires that have been attached, e.g. laser welded. In one embodiment, the junctions  146  move independently of the stent. Specifically, the junction end of the leaflet assembly may not be attached to the stent, but only the upper portion. Having unattached junctions with the ability to flex inward and, more importantly, expand outward, gives the leaflet wire form the structural ability to collapse when compressed and expand when deployed. The ability to compress and expand independently of one another, relieves mechanical stresses on the tissue. 
         [0139]    Referring now to  FIG. 4 ,  FIG. 4  shows inner rim  130  and outer rim  132  of cuff  116 . Spindles  122  are shown between the outer rim  128  and the inner rim  130 . Valve leaflets  120  are shown within the inner rim  130 . 
         [0140]      FIG. 5  shows a side view from slightly below the horizontal plane of one embodiment of a prosthetic valve according to the present invention to show the bottom surface of the cuff.  FIG. 5  shows stent  112  having three tether attachment structures  114  projecting from the distal end of stent  112  for attaching to tethers  138 . 
         [0141]      FIG. 5  shows an example of an embodiment wherein the cuff  116  is formed from the stent  112  by heating and shaping. 
         [0142]      FIG. 6  shows an example of an embodiment wherein the cuff  116  and stent  112  are formed from two joined pieces.  FIG. 6  also shows that tethers  138  are not attached to the leaflet assembly or leaflet wire form  148  and  146  (shown for illustration purposes but would not be visible through tissue or synthetic material, e.g. liner), but rather the tethers  138  are contemplated as attaching to the stent  112 , to the base of the cuff  116 , to an upper portion of the cuff  116 , or a combination of the above. 
         [0143]    Referring now to  FIG. 7 , there is shown an example of where the cuff spindles may vary in design size and shape.  FIG. 7  shows a completely expanded prosthetic valve  110  fully expelled from the flexible delivery catheter, including cuff wire form  122 , cuff tissue covering  124 , tethers  138 , tubular stent  112 , sealed joint  170 , tether attachment  114 , and tethers  138 .  FIG. 7  illustrates where every other spindle is longer than the adjacent showing an alternating pattern. This provides an advantage of additional coverage and compliance of various cuff designs, in combination with how tethers  138  are pulled and shortened to adjust or move the prosthetic valve towards and within the valvular annulus where it will be seated, adjusted, and fastened in place to complete the deployment.  FIG. 7  also shows that tethers  138  are not attached in this embodiment to the leaflet assembly or leaflet wire form  148  and  146  (shown for illustration purposes but would not be visible through tissue or synthetic material, e.g. liner). 
         [0144]      FIG. 8  shows another variation of one preferred embodiment of the present invention where the spindles do not alternate, but rather two spindles on either side create an elongated cuff for a prosthetic valve where this provides an advantage. Sealed joint  170  is shown where the stent body connects to the cuff. 
         [0145]      FIG. 9  shows a top view of a three-leaflet structure  156  as though from inside the left atrium looking down toward the left ventricle, and shows the completely expanded prosthetic heart valve  110  seated and adjusted to form a tight seal within the mitral annulus.  FIG. 9  also shows valve leaflets  120 , cuff  116 , and independent loops of wire  122 . 
         [0146]    Referring now to  FIG. 10 , there is provided an illustration of how the cuff and stent body may be formed in such a manner to create various positions, e.g. angles, for the cuff. The angular relationship between the cuff  116  and the stent  112  function to seal the prosthetic heart valve against the mitral valve aperture and prevent leaking. In one embodiment,  FIG. 10A , the angle of the cuff may also include a more acute inverted-funnel shaped angle. Although not limiting, in one example, the angle is 60 degrees.  FIG. 10B  illustrates the angle of an approximately perpendicular angle.  FIG. 10C  illustrates a more obtuse funnel-shaped angle, e.g. 150 degrees, in relation to the longitudinal axis of the stent. 
         [0147]      FIG. 11  shows how tines or barbs can facilitate the attachment to the tissue, such as the mitral annulus or the tricuspid, annulus.  FIG. 11  shows cuff  116  attached to stent body  112  where barbs  158  have been attached at the neck of the prosthetic valve where the cuff meets or transitions to the stent body. 
         [0148]      FIG. 12  A-B illustrates a specific form of hooked barb  158  where the hooked barb is adjusted to provide an opening between the barb and the stent body where an operator would direct the annular tissue to assist with seating the valve. Upon placing the prosthetic valve  110  there, a balloon catheter or other expansion means is inserted into the stent  112  to expand the internal diameter, thus causing the hooked barbs  158  to rotate back inwards toward the stent  112 , thus capturing and locking the annular tissue to the stent body. 
         [0149]      FIG. 13  shows a prosthetic valve according to the present invention showing tethers  160  attached to the cuff portion  116  with optional cuff-tether attachments  162  in addition to attachment  114  of the tethers  138  on the stent body. By providing the surgeon the ability to control, adjust, tighten, the cuff geometry relative to the stent geometry, many options are provided that were not heretofore known to be available in the prior art. 
         [0150]    Referring now to  FIG. 14 , this is a drawing of one preferred embodiment of equipment as claimed herein that is used to compress the prosthetic valve and insert the prosthetic valve into the heart.  FIG. 14  shows funnel compressor  142 , introducer  144 , snare  150 , flexible deployment catheter  134 , catheter insert  152 , and obturator  136 , the implementation of which is further described in  FIG. 15 . 
         [0151]    Referring now to  FIGS. 15A-F  is a series of drawings of one embodiment of the assembly of a delivery system for a prosthetic valve according to the present invention.  FIGS. 15A-F  show the preparation of the prosthetic valve for implantation into the heart by showing how the prosthetic valve is loaded into the flexible delivery catheter.  FIG. 15A  shows the initial step of attaching the introducer  144  to the compression funnel  142 .  FIG. 15B  shows the snare  150  pulling tethers  138  into compression funnel  142  and threading through introducer  144 .  FIG. 15C  shows the prosthetic valve  110  just prior to being drawn into the compression funnel  142  as it is pulled rear-ward using tethers  138  into the introducer  144 .  FIG. 15D  shows the prosthetic valve  110  (not shown) inserted into the introducer  144  with the anchoring tethers  138  extending from the rear of the introducer  144 .  FIGS. 15  E and  15 F show the flexible delivery (deployment) catheter  134  being attached to the introducer  144  to introduce, or insert, the compressed prosthetic valve  110  (not shown) into the flexible delivery catheter  134 . In summary,  FIG. 15  shows prosthetic valve  110  with tethers  138  that have been threaded, using a snare  150 , through the funnel compressor  142  which is attached to introducer  144 . Upon pulling the tethers  138 , the prosthetic valve  110  is mechanically compressed by the funnel  142  and inserted into the introducer  144 . The introducer  144  is then inserted into the delivery catheter  134  in preparation for loading the delivery catheter. The obturator  136 , having diameter slightly less than the introducer and the delivery catheter, is then inserted into the rear portion of the introducer and pushes the compressed and tethered prosthetic valve into the delivery catheter. It is contemplated that this process will be performed in the operating room just prior to installing the valve in the patient. In another embodiment, a ready-made pre-filled catheter/valve delivery system is provided. 
         [0152]    Referring now to  FIG. 16  is a detailed sectional view of the catheter delivery system  132 , which includes the compressed prosthetic valve  110  according to the present invention disposed within the delivery catheter  134 .  FIG. 16  shows prosthetic valve  110  having cuff  116  attached to stent  112 , which further has tethers  138  leading away from the compressed valve  110 . 
         [0153]      FIG. 17  is a cut-away view of a heart with a delivery catheter containing a prosthetic heart valve according to the present invention and accessing the heart using an apical approach. It is contemplated that other surgical approaches to the heart, and valves in addition to the mitral valve, are within the scope of the inventive subject matter claimed herein.  FIG. 17  shows the delivery catheter  134  advanced to through the mitral valve and into the left atrium for deployment of the prosthetic valve  110 . 
         [0154]      FIG. 18  A-D is a series of drawings of the deployment of one embodiment of a prosthetic valve according to the present invention.  FIG. 18  A-D is a series of views of the tip of one embodiment of a delivery catheter according to the present invention containing a pre-loaded prosthetic valve which is being pushed out of the delivery catheter, i.e. by an obturator, starting with (A) the valve completely within the catheter, (B) the cuff portion being in view, (C) the stent body following, and (D) the prosthetic valve with attached tethers for positioning and/or adjustment and/or securing the valve to tissue.  FIGS. 18A-D  shows how the prosthetic valve  110  is deployed from flexible deployment catheter  134 .  FIG. 18B  shows the cuff  116  emerging from the catheter  134 .  FIG. 18C  shows the cuff  116  and stent  112  partially expelled from the delivery catheter  134 .  FIG. 18D  shows the prosthetic valve completely expelled from the delivery catheter  134  with tethers  138  attached to the stent body and trailing behind into the catheter.  FIG. 18D  further shows tethers  138  attached to the stent  112 , with prosthetic valve  110  now expanded and delivered (but not positioned or adjusted), as the delivery catheter  134  is withdrawn away from the target location, e.g. atrium. 
         [0155]    Referring now to  FIG. 19 ,  FIG. 19  shows a depiction of a fully deployed prosthetic heart valve  110  installed in the left mitral valve of the heart having the tethers  138  attached to the left ventricle apex of the heart. Tethers  138  in this embodiment extend through the heart muscle and are attached to securing device  140 , here shown as a pledget placed on the epicardial surface and having tethers fastened thereto. 
         [0156]    In this embodiment, the pledget  140  performs the function of an anchor to which the tethers  138  are attached. Tethers  138  are strung through the left ventricle apex and pulled downward to seat prosthetic valve  110  in the atrial valve area. The completely installed prosthetic valve is held in the left atrium by the cuff  116  and secured to the apex of the heart by tethers  138 . The tethers may be held in place by a securing device which in this aspect of the invention is a pledget  140  that the tethers are threaded through and secured against, i.e. by tying a knot or using a cinching feature. 
         [0157]    Referring now to  FIG. 20  is a detailed cross-sectional view (of the heart) of one embodiment of a prosthetic heart valve according to the present invention deployed within the mitral valve aperture of the heart and anchored, in an alternative embodiment, between (A) where it is seated or lodged by the atrial cuff and (B) the ventricular tethers connected to papillary muscles  166  and/or ventricular wall and/or tether(s) attached to septum  164 , which are each secured by one or more securing tissue anchors, anchoring devices, or anchoring methods. 
         [0158]      FIG. 21A-B  shows how the tethers  138  are tied off at the apex of the heart after deployment of the prosthetic valve  110 .  FIG. 21A  shows the flexible delivery catheter  134  inserted into the left ventricular apex along with a suture  156  having partially installed apical-closure/tissue-buttressing material  158 .  FIG. 21B  shows the anchoring system of the prosthetic valve in which the ventricular tethers  138  are shown treaded through the left ventricle apex and through a partially installed pledget  140 ; also shown are fully installed apical suture-closure material  156 / 158 . Tissue buttressing material may optionally be in one embodiment a pledget felt. 
         [0159]    Referring now to  FIGS. 22  A-B,  FIGS. 22  A-B is a pair of drawings of the lateral deployment of one embodiment of a prosthetic valve according to the present invention and shows a prosthetic valve delivery catheter that has accessed the left atrium via the left ventricle by way of a lateral trans-ventricular wall approach through the lateral wall of the left ventricle of the heart.  FIGS. 22  A-B show a prosthetic valve delivery catheter that (A) has accessed the left atrium via the left ventricle by way of a lateral trans-ventricular wall approach through the lateral wall of the left ventricle of the heart, to be deposited the prosthetic valve into the left atrium, which will be withdrawn the delivery catheter for adjustment of the tethers, and (B) that has the valve adjusted and deployed within the mitral annulus. 
         [0160]      FIG. 22B  is an illustration of the prosthetic heart valve  110  seated within the mitral annulus and, in this embodiment, having papillary muscle tethers  166  within the left ventricle.  FIG. 22B  also shows annulus barbs  158 , here shown optionally at both the transition point from the stent to the cuff  158  and elsewhere on the cuff itself  168 . 
         [0161]      FIG. 23  is a cut-away view of a heart with a delivery catheter containing a prosthetic heart valve according to the present invention and accessing the right ventricle of the heart using an apical approach.  FIG. 23  shows the delivery catheter advanced through to the tricuspid valve and into the right atrium for deployment of the prosthetic heart valve. 
         [0162]    Referring now to  FIGS. 24  A-B that show an embodiment of a prosthetic valve  110  having a ring or halo feature  154 .  FIG. 24A  is a bottom view from slightly above the horizontal plane of one embodiment of a prosthetic valve according to the present invention to show the bottom surface of the cuff  116  and the halo feature  154 .  FIG. 24B  is a top view from slightly above the horizontal plane of one embodiment of a prosthetic valve according to the present invention to show the top surface of the cuff  116 . 
         [0163]      FIGS. 24  A-B show an embodiment of a prosthetic valve having a ring or halo feature  154  attached to the junctions  146  of the arched wires  148  of leaflet assembly  118 . 
         [0164]    The references recited herein are incorporated herein in their entirety, particularly as they relate to teaching the level of ordinary skill in this art and for any disclosure necessary for the commoner understanding of the subject matter of the claimed invention. It will be clear to a person of ordinary skill in the art that the above embodiments may be altered or that insubstantial changes may be made without departing from the scope of the invention. Accordingly, the scope of the invention is determined by the scope of the following claims and their equitable Equivalents.