RELATED APPLICATIONS 
       [0001]    The present application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Application 61/772,212 filed on Mar. 4, 2013, the disclosure of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments of the invention relate to devices and instruments for implementing cardiac valve corrective surgery. 
       BACKGROUND 
       [0003]    The human heart, and generally all mammalian hearts, comprises two blood pumps that operate in synchrony to oxygenate and deliver oxygenated blood to the body. A first pump receives deoxygenated blood after it has coursed through blood vessels in the circulatory system to deliver oxygen and nutrients to the various parts the body, and pumps the deoxygenated blood through the lungs to be oxygenated. The second pump receives the oxygenated blood from the lungs and pumps it to flow through the blood vessels of the circulatory system and deliver oxygen and nutrients to the body parts. The two pumps are located adjacent each other in the heart and each pump comprises two chambers, an atrium that receives blood and a ventricle that pumps blood. 
         [0004]    The first pump, which receives deoxygenated blood to be pumped to the lungs, is located on the right side of the heart and its atrium and ventricle are accordingly referred to as the right atrium and right ventricle. The second pump, which receives oxygenated blood to be pumped to the body, is located on the left side of the heart and its atrium and ventricle are referred to as the right atrium and right ventricle of the heart. The right and left atria are separated by a wall in the heart referred to as the interatrial septum and the right and left ventricles are separated by a wall in the heart referred to as the interventricular septum. 
         [0005]    Deoxygenated blood enters the right atrium via blood vessels referred to as the superior vena cava and inferior vena cava. During a part of the heart cycle referred to as diastole the right ventricle is relaxed and the deoxygenated blood in the right atrium flows from the right atrium into the right ventricle via a valve, referred to as a tricuspid valve, which connects the right atrium to the right ventricle. The right ventricle contracts during a part of the heart cycle referred to as systole, to pump the deoxygenated blood that it receives from the right atrium out of the ventricle and into the pulmonary artery via a valve referred to as the pulmonary valve, which interfaces the pulmonary artery with the right ventricle. The pulmonary artery delivers the deoxygenated blood to the lungs for oxygenation. The tricuspid and pulmonary valves control direction of blood flow in the right side of the heart. The tricuspid valve opens to let deoxygenated blood flow from the right atrium into the right ventricle and closes to prevent deoxygenated blood from regurgitating into the right atrium when the right ventricle contracts. The pulmonary valve opens to let blood enter the pulmonary artery when the right ventricle contracts and closes to prevent blood regurgitating into the right ventricle when the right ventricle relaxes to receive blood from the right atrium. 
         [0006]    The left atrium receives oxygenated blood from the lungs via pulmonary veins. Oxygenated blood flows from the left atrium into the left ventricle during diastole via a bileaflet valve referred to as the mitral valve, which opens during diastole to allow blood flow from the left atrium to the left ventricle. The left ventricle contracts during systole to pump the oxygenated blood that it receives from the left atrium out of the heart through the aortic valve and into the aorta, for delivery to the body. The mitral valve operates to prevent regurgitation of oxygenated blood from the left ventricle to the left atrium when the left ventricle contracts to pump oxygenated blood into the aorta. The aortic valve closes to prevent blood from regurgitating into the left ventricle when the left ventricle relaxes to receive blood from the left atrium. 
         [0007]    Each valve comprises a set of matching “flaps”, also referred to as “leaflets” or “cusps”. that are mounted to and extend from a supporting structure of fibrous tissue. The supporting structure has a shape reminiscent of an annulus and is often conventionally referred to as the annulus of the valve. The leaflets are configured to align and overlap each other, or coapt, along free edges of the leaflets to close the valve. The valve opens when the leaflets are pushed away from each other and their free edges part. The aortic, pulmonary, and tricuspid valves comprise three leaflets. The mitral valve comprises two leaflets. 
         [0008]    The leaflets in a valve open and close in response to a gradient in blood pressure across the valve generated by a difference between blood pressure on opposite sides of the valve. When the gradient is negative in a “downstream flow” or antegrade direction, in which direction the valve is intended to enable blood flow, the leaflets are pushed apart in the downstream, antegrade direction by the pressure gradient, and the valve opens. When the gradient is positive in the downstream direction, the leaflets are pushed together in the upstream or retrograde direction so that their respective edges meet to align and coapt, and the valve closes. 
         [0009]    For example, the leaflets in the mitral valve are pushed apart during diastole to open the mitral valve and allow blood flow from the left atrium into the left ventricle when pressure in the left atrium is greater than pressure in the left ventricle. The leaflets in the mitral valve are pushed together so that their edges coapt to close the valve during systole when pressure in the left ventricle is greater than pressure in the left atrium to prevent regurgitation of blood into the left atrium. 
         [0010]    Each valve is configured to prevent misalignment or prolapse of its leaflets as a result of positive pressure gradients pushing the leaflets upstream past a region in which the leaflets properly align and coapt to close the valve. A construction of fibrous tissue in the leaflets of the pulmonary and aortic valves operates to prevent prolapse of the leaflets in the pulmonary and aortic valves. A configuration of cord-like tendons, referred to as chordae tendineae, connected to muscular protrusions, referred to as papillary muscles, that project from the left ventricle wall, tie the leaflets of the mitral valve to the walls of the left ventricle. The chordae tendineae provide dynamic anchoring of the mitral valve leaflets to the left ventricle wall that operate to limit upstream motion of the leaflets and prevent their prolapse into the left atrium during systole. Similarly, a configuration of chordae tendineae and papillary muscles cooperate to prevent prolapse of the tricuspid valve leaflets into the right atrium. 
         [0011]    Efficient cardiac valve function can be complex and a cardiac valve may become compromised by disease or injury to an extent that warrants surgical intervention to effect its repair or replacement. For example, normal mitral valve opening and closing and prevention of regurgitation of blood from the left ventricle into the left atrium is dependent on coordinated temporal cooperation of the mitral leaflets, the mitral annulus, the chordae, papillary muscles, left ventricle, and left atrium. Malfunction of any of these components of a person&#39;s heart may lead to mitral valve dysfunction and regurgitation that warrants surgical intervention to provide the person with an acceptable state of health and quality of life. 
       SUMMARY 
       [0012]    An aspect of an embodiment of the invention relates to providing a structure and procedures for emplacing and securing the structure to an annulus of a cardiac valve that may operate to improve functioning of the valve, and/or provide structural support for apparatus that operates to improve functioning of the valve. According to an aspect of an embodiment of the invention, the structure, hereinafter also referred to as an “annular brace” or a “brace”, is configured to grip and anchor to an annulus of a cardiac valve in a region of a commissure of the valve. 
         [0013]    In an embodiment of the invention, the annular brace comprises first and second bottom gripping wings and first and second top gripping wings for gripping and anchoring to the annulus of the cardiac valve in a region of the commissure. The top gripping wings are connected to the bottom gripping wings by a support bridge. The annular brace has a delivery configuration and a deployed configuration, and is formed from a suitable deformable biocompatible material so that the brace is deformable from the delivery configuration to the deployed configuration. Optionally, the deformable biocompatible material is a shape memory alloy such as nitinol. In the delivery configuration the shape memory alloy brace may be in a martensite state and in the deployed configuration the material may be in an austenite state. 
         [0014]    In the delivery configuration the first and second bottom gripping wings are folded to lie substantially back to back along a same axis and the first and second top gripping wings are folded to lie substantially back to back along the same axis along which the bottom gripping wings lie. In the deployed configuration, the first top and first bottom gripping wings oppose each other to grip a first region of the annulus between them, and the second top and second bottom gripping wings oppose each other to grip a second region of the annulus between them. The gripping wings are shaped to conform to the curvature of the annular regions that they grip. The first and second regions of the annulus lie on opposite sides of the commissure. 
         [0015]    A deployment catheter houses the brace in the delivery configuration for delivery to and for positioning the brace for deployment at the cardiac valve. Following delivery and positioning at the commissure, the deployment catheter is controlled to release the annular brace so that the brace may deform to the deployed state and grip and anchor to the annulus. 
         [0016]    In an embodiment of the invention, the top and bottom first gripping wings are integral portions of a same first “gripping strip” of an elastically deformable biocompatible material and the top and bottom second gripping wings are integral portions of a second gripping strip of an elastically deformable biocompatible material. A bridge portion of the first gripping strip located between the first gripping strip&#39;s top and bottom wings is connected to a bridge portion of the second gripping strip located between the second gripping strip&#39;s top and bottom gripping wings to form the bridge connecting both top wings to both bottom wings. 
         [0017]    In the delivery configuration of the annular brace, the strips are flat and lie substantially back to back. In the deployed configuration the strips are bent so that the top and bottom wings of the first strip face each other to grip the first region of the annulus and the top and bottom wings of the second strip face each other to grip the second region of the annulus. The deployment catheter that houses the brace for delivery to the annulus optionally constrains the brace to the brace&#39;s delivery configuration. Upon release from the deployment catheter, the brace, optionally, self deforms to the brace&#39;s deployed configuration. 
         [0018]    In an embodiment of the invention the first and second gripping strips are separate strips and their respective bridge portions are connected using any of various suitable joining process, such as bonding, gluing, welding, or brazing. Optionally, the first and second gripping strips and the bridge are integral parts of a same piece, hereinafter also referred to as a “die-shape”, of material shaped by a process such as by way of example, stamping or laser cutting from a sheet of an elastically deformable biocompatible material. Suitably bending the die-shape deforms the die-shape to the delivery configuration of the brace. 
         [0019]    In an embodiment of the invention, the annular brace comprises a wireform that is bent to provide the first and second top and bottom wings. Optionally, the wireform is cut or stamped from a sheet of an elastically deformable biocompatible material. 
         [0020]    In an embodiment of the invention an annular brace is mounted to the annulus of a cardiac valve of a patient at a region of each commissure of the valve to treat compromised performance of the valve. Leaflet restraining struts may be mounted to the braces on the atrial side of the valve to constrain motion of the valve leaflets and improve performance of the valve. In an embodiment of the invention the valve may be the mitral or tricuspid valve and the restraining struts are mounted to the atrial side of the valve to prevent prolapse of the leafs into the left or right atrium respectively. 
         [0021]    There is therefore provided in accordance with an embodiment of the invention, a brace for mounting to an annulus of a cardiac valve, the brace comprising: first and second bottom gripping wings for gripping the annulus; first and second top gripping wings for gripping the annulus; and a support bridge that connects the top wings to the bottom wings; wherein the brace is deformable from a delivery configuration to a deployed configuration and in the delivery configuration the top wings are oriented substantially back to back along an axis and the bottom wings are oriented substantially back to back along the same axis, and in the deployed configuration the first top and bottom gripping wings face each other to grip the annulus between them and the second top and bottom gripping wings face each other to grip the annulus between them. 
         [0022]    In an embodiment of the invention, the first top and first bottom gripping wings are integral parts of a same first strip of material separated by a bridge portion of the first strip. Optionally, the second top and second bottom gripping wings are integral parts of a same second strip of material separated by a bridge portion of the second strip. 
         [0023]    In an embodiment of the invention, the first top and second top gripping wings are integral parts of a same first strip of material separated by a bridge portion of the first strip. Optionally, the first bottom and second bottom gripping wings are integral parts of a same second strip of material separated by a bridge portion of the second strip. 
         [0024]    In an embodiment of the invention, the first and second strips of material are separate strips that are joined by connecting the bridge portion of the first strip to the bridge portion of the second strip to form the bridge. 
         [0025]    In an embodiment of the invention, the first and second strips of material are integral parts of a same flat piece of material that is bent in a region of the piece of material connecting the bridging regions of the first and second strips to form the bridge. 
         [0026]    The brace may comprise at least one anchor tooth on at least one or more of the gripping wings that penetrates into the annulus when the brace is mounted to the annulus. 
         [0027]    The first top gripping wing may comprise a stabilizer tooth that faces the first bottom gripping wing to grip the annulus between the stabilizer tooth and first bottom gripping wing prior to completion of mounting the brace to the annulus. 
         [0028]    In an embodiment of the invention, the brace comprises a wireform having first and second wire-loops connected by the support bridge. Optionally, the support bridge comprises at least one wire segment. 
         [0029]    In an embodiment of the invention, the first top and first bottom gripping wings are wireform gripping wings comprised in the first wire-loop. 
         [0030]    In an embodiment of the invention, the second top and second bottom gripping wings are wireform gripping wings that are comprised in the second wire-loop. 
         [0031]    In an embodiment of the invention, the first and second top gripping wings are wireform gripping wings comprised in the first wire-loop. In an embodiment of the invention, the first and second bottom gripping wings are wireform gripping wings comprised in the second wire-loop. 
         [0032]    In an embodiment of the invention, the brace is formed from a shape memory material, and in the delivery configuration the material is in a martensite state and in the deployed configuration the material is in an austenite state. 
         [0033]    There is further provided in accordance with an embodiment of the invention apparatus for treating prolapse of a leaflet of a cardiac valve comprising an annulus that supports at least two leaflets that meet at least two commissures, the apparatus comprising: a first brace according to any of the preceding claims configured to be mounted to the annulus in a region of a first commissure of the at least two commissures; a second brace according to any of the preceding claims configured to be mounted to the annulus in a region of a second commissure of the at least two commissures; and at least one restraining strut mountable to the first and second braces after the braces are mounted to the annulus. 
         [0034]    In the discussion, unless otherwise stated, adjectives such as “substantially” and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment of the invention, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended. Unless otherwise indicated, the word “or” in the description and claims is considered to be the inclusive “or” rather than the exclusive or, and indicates at least one of, or any combination of items it conjoins. 
         [0035]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0036]    Non-limiting examples of embodiments of the invention are described below with reference to figures attached hereto that are listed following this paragraph. Identical features that appear in more than one figure are generally labeled with a same label in all the figures in which they appear. A label labeling an icon representing a given feature of an embodiment of the invention in a figure may be used to reference the given feature. Dimensions of features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale. 
           [0037]      FIG. 1  schematically shows a cross section of a human heart that displays the heart chambers and cardiac valves; 
           [0038]      FIG. 2A  schematically shows a cutaway perspective view of a human heart that provides a perception of the three dimensional structure of the mitral and tricuspid valves of the heart; 
           [0039]      FIG. 2B  schematically shows the cutaway perspective view of a human heart similar to that shown in  FIG. 2A  with the anterior leaflet of the mitral valve cutaway for convenience of presentation; 
           [0040]      FIG. 3  schematically shows an annular brace mounted to the annulus of the mitral valve shown in  FIG. 2B , in accordance with an embodiment of the invention; 
           [0041]      FIGS. 4A-4C  schematically illustrate construction of the annular brace shown deployed in  FIG. 3 , in accordance with an embodiment of the invention; 
           [0042]      FIGS. 4D and 4E  schematically show variations of annular braces similar to the annular brace shown in FIGS.  3  and  4 A- 4 C, in accordance with an embodiment of the invention; 
           [0043]      FIGS. 4F-4H  schematically show stages in deployment of the brace shown in  FIG. 3 , in accordance with an embodiment of the invention; 
           [0044]      FIG. 4I  schematically shows an annular brace having stabilizer teeth that function to facilitate stabilization of deployment of an annular brace during deployment, in accordance with an embodiment of the invention; 
           [0045]      FIGS. 5A-5D  schematically illustrate a transseptal deployment of the annular brace shown in FIGS.  3  and  4 A- 4 G, in accordance with an embodiment of the invention; 
           [0046]      FIG. 6  schematically shows a view from the atrial side of a mitral valve having an annular brace mounted at each commissure of the valve and leaflet restraining struts mounted to the braces, in accordance with an embodiment of the invention; and 
           [0047]      FIGS. 7A-7C  schematically show a wireframe annular brace, in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0048]      FIG. 1  shows a schematic, stylized cross section of a human heart  20  having a right atrium  31  and a right ventricle  32  that communicate via a tricuspid valve  33  and a left atrium  41  and left ventricle  42  that communicate via a mitral valve  43 . Tricuspid valve  33  has three leaflets  34 , only two of which are shown in  FIG. 1 , that are tied by chordae tendineae  35  and papillary muscles  36  to the wall  37  of the right ventricle. Right ventricle  32  communicates with the pulmonary artery  38  via the pulmonary valve  39 . Mitral valve  43  has two leaflets, anterior and posterior leaflets  44  (anterior leaflet  44  is in continuity with the wall of the aorta) and  45  respectively that are supported and extend from the mitral annulus  46 . Mitral valve leaflets  44  and  45  are respectively tied by chordae tendineae  47  and papillary muscles  48  to the ventricle wall  49 . The left ventricle communicates with the aorta  50  via the aortic valve  51 . 
         [0049]    Deoxygenated blood returning from parts of the body enters right atrium  31  and passes through tricuspid valve  33  to enter right ventricle  32  during diastole when leaflets  34  of the tricuspid valve are separated (as schematically shown in  FIG. 1 ) to open the tricuspid valve and the right ventricle is relaxed. Flow of deoxygenated blood into the right atrium via the inferior vena cava  30  and through tricuspid valve  33  into the right ventricle is schematically indicated by dashed line block arrows  61 . During systole right ventricle  32  contracts to pump the deoxygenated blood through pulmonary valve  39  and into pulmonary artery  38  for delivery to the lungs. During systole leaflets  34  of tricuspid valve  33  coapt and the tricuspid valve  33  closes to prevent deoxygenated blood pumped by the right ventricle from regurgitating into the right atrium. Flow of deoxygenated blood pumped by right ventricle  32  into pulmonary artery  38  is schematically indicated by solid line block arrow  62 . 
         [0050]    Oxygenated blood from the lungs enters left atrium  41  and passes through mitral valve  43  to enter left ventricle  42  during diastole when leaflets  44  and  45  are separated (as shown in  FIG. 1 ) to open the mitral valve and the left ventricle is relaxed. Flow of oxygenated blood into the left atrium and through mitral valve  43  into the left ventricle is schematically indicated by dashed block arrows  71 . During systole left ventricle  42  contracts to pump the oxygenated blood through the aortic valve  51  and into the aorta  50  for delivery to the body. During systole leaflets  44  and  45  coapt to close mitral valve  43  and prevent oxygenated blood pumped by the left ventricle from regurgitating into the left atrium. 
         [0051]    Valves  33 ,  39 ,  43 , and  51  operate to direct flow of blood in the heart and out from the heart and their proper and efficient function are required to maintain a person&#39;s health and quality of life. Various different disease processes may result in damage to a heart valve and compromise valve functioning. For example, functioning of the mitral valve may be compromised by various degrees of stenosis, calcification, distortion of the mitral valve annulus, torn chordae tendineae, and faulty left ventricle functioning. Valve dysfunction and concomitant regurgitation may become so severe as to warrant surgical intervention to provide a person with an acceptable state of health and quality of life. 
         [0052]      FIG. 2A  schematically shows a cutaway perspective view of a human heart  20  that provides a perception of the three dimensional structure of mitral valve  43  and tricuspid valve  33 . In the figure, a portion of annulus  46  of mitral valve  43  that supports mitral valve anterior and posterior leaflets  44  and  45  is shown shaded, and a region of a commissure  46 -C at which the leaflets come together is indicated. For convenience of presentation and the discussion that follows,  FIG. 2B  schematically shows heart  20  in which anterior leaflet  44  shown in  FIG. 2A  is cutaway substantially to annulus  46 , and chordae tendineae  47  that connect the anterior leaflet to papillary muscles  48  are removed. 
         [0053]      FIG. 3  schematically shows an annular brace  100  mounted to annulus  46  in the region of commissure  46 -C in accordance with an embodiment of the invention. Annular brace  100  comprises first and second top gripping wings  101  and  102  and first and second bottom gripping wings  103  and  104 . In the perspective of  FIG. 3  bottom gripping wing  104  is hidden by posterior leaflet  45  and is not shown. Top gripping wings  101  and  102  are joined to bottom gripping wings  103  and  104  by a bridge  105 . Optionally, top gripping wings  101  and  102  are formed having mounting holes  110  for mounting apparatus to annular brace  100  that a medical practitioner may determine to be advantageous for ameliorating a mitral valve dysfunction. 
         [0054]      FIGS. 4A-4H  schematically illustrate construction and stages in a deployment of annular brace  100  shown in  FIG. 3 , in accordance with an embodiment of the invention. Brace  100  is optionally formed from a planar die-shape  90 , schematically shown in  FIG. 4A . The die-shape optionally comprises a gripping strip  91  having top gripping wings  101  and  102 , and a gripping strip  92  having bottom gripping wings  103  and  104 . A bridging region  93  connects gripping strips  91  and  92 . Optionally, die-shape  90  is “scalloped” to produce recesses  106  in which annulus  46  seats when brace  100  is fully deployed as shown in  FIG. 3 . A dashed line  94  on die-shape  90  indicates a fold line along which bridging region  93  is folded to form bridge  105  ( FIG. 3 ). Folding bridging region  93  along fold line  94  produces annular brace  100  in the brace&#39;s delivery configuration as schematically shown in  FIG. 4B . Dashed lines  95  shown in  FIGS. 4A and 4B  indicate bend lines along which gripping wings  101 - 104  bend to deform brace  100  from the delivery configuration of the brace to the deployed configuration of the brace in which the brace grips annulus  46 , as shown in  FIG. 3 .  FIG. 4C  shows annular brace  100  as it appears in the deployed configuration, without annulus  46 . 
         [0055]    It is noted, as shown in  FIGS. 3 and 4C , that in the deployed state, gripping wings  101 - 104  not only bend along bend lines  95  but also optionally deform to conform to a curvature of annulus  46  at the location of commissure  46 -C at which the brace is deployed. In an embodiment of the invention, to enable sufficient curvature of top and bottom gripping wings  101 - 104  to conform to curvature of a cardiac valve annulus, such as annulus  46  of mitral valve  43  or an annulus of a tricuspid valve, to which an annular brace, similar to annular brace  100 , is mounted, the gripping wings may be slotted. Optionally, to facilitate anchoring brace  100  to the cardiac valve annulus, a gripping wing of the brace is formed having an anchor tooth that bites into the annulus when the gripping wing is deployed. In an embodiment of the invention, each wing of the annular brace is fitted, optionally at an end of the gripping wing, with at least one anchor tooth. By way of example  FIG. 4D  schematically shows an annular brace  120  similar to annular brace  100 , in which gripping wings  101 - 104  are formed having slots  122  that facilitate curving of the gripping wings to conform to curvature of a cardiac valve annulus. Each wing  101 - 104  comprises an anchoring tooth  124  at an end of the wing. 
         [0056]    Die-shape  90  ( FIG. 4A ) may be produced by way of example, by sintering, molding, or by cutting or stamping, from a sheet of a suitable elastically deformable material. Optionally, the material is a shape memory material which may be a shape memory alloy, such as nitinol, or a shape memory polymer. In an embodiment of the invention, the shape memory material is in a martensite state when brace  100  is in the delivery configuration and is in an austenite state when the brace deforms to the deployed configuration, which is a configuration the shape memory material is conditioned to remember. Any of various methods known in the art may be used to condition brace  100  to remember the deployed configuration. It is noted that a die-shape similar to die-shape  90  may be folded and conditioned to provide an annular brace  160  schematically shown in  FIG. 4E  that is similar to annular braces  100  and  120 , but in which top gripping wings are gripping wings  102  and  104  and bottom gripping wings are gripping wings  101  and  103 . 
         [0057]      FIGS. 4F-4I  schematically show stages in the delivery of brace  100  to mitral valve  43 , in accordance with an embodiment of the invention. In  FIG. 4F  brace  100  is housed in a deployment catheter  150  schematically indicated in dashed lines. Optionally deployment catheter  150  has a rectangular or square cross section so that the catheter constrains brace  100  to the brace&#39;s delivery configuration as long as the brace is confined by the catheter. Optionally, deployment catheter  150  comprises a push rod  152  that is controllable to push brace  100  out from deployment catheter  150  and deploy the brace at mitral valve  43 .  FIG. 4G  schematically shows annular brace  100  after push rod  152  has partially pushed the brace out of deployment catheter  150  to release bottom gripping wings  103  and  104  from the deployment catheter. Upon being pushed out from deployment catheter  150 , and released from confinement by the deployment catheter, bottom gripping wings  103  and  104  bend from bridge  105  away from each other to their deployed orientation as schematically shown in  FIG. 4H . Upon push rod  152  pushing annular brace  100  completely out of deployment catheter  150 , top gripping wings  101  and  102  bend to their deployed state as shown in  FIG. 4C  and grip annulus  46  as shown in  FIG. 3 . 
         [0058]      FIGS. 4F-4I  show delivery catheter  150  fitting snugly to brace  100  and constraining the brace to a delivery configuration in which the brace appears to fit snugly in a rectangular volume. However, in an embodiment of the invention, delivery catheter  150  may have a sufficiently large cross section to allow a brace, similar to brace  100  to be delivered in a delivery configuration that is partially deformed from the delivery configuration shown in  FIGS. 4B and 4F  to the deployed configuration shown in  FIG. 4C . 
         [0059]    By way of a numerical example, die shape  90  may have a thickness between about 0.5 mm to about 3 mm, wings  101 - 104  may lengths between about 5 mm to about 20 mm and widths between about 2 mm and about 5 mm. Delivery catheter may have an internal diameter up to about 7.5 mm. 
         [0060]    In some embodiments of the invention an annular brace similar to annular brace  100  may have stabilizer teeth that deploy from top gripping wings as the annular brace is pushed out of deployment catheter  150  after bottom gripping wings  103  and  104  are deployed and a portion, but not all, of top gripping wings  101  and  102  are released from the deployment catheter. The stabilizer teeth aid in maintaining position of the annular brace during deployment of the brace.  FIG. 4I  schematically shows an annular brace  140  having stabilizer teeth  142  deployed on an upper surface of annulus  46  after bottom gripping wings  103  and  104  are deployed and top gripping wings  101  and  102  are partially extended from deployment catheter  150 . 
         [0061]      FIGS. 5A-5D  schematically show a transseptal procedure for deploying annular brace  100  at mitral valve  43 , in accordance with an embodiment of the invention.  FIG. 5A  schematically shows deployment catheter  150  after the deployment catheter has been threaded into right atrium  31  via the inferior vena cava  30  ( FIGS. 1-2B ) and been delivered through a puncture in the atrial septum (not shown) into the left atrium. In the left atrium, deployment catheter  150  has been controlled to position annular brace  100  housed in the catheter for mounting to annulus  46 . In  FIG. 5A  annular brace  100  is housed in catheter  150  as shown in  FIG. 4F . In  FIG. 5B  push rod  152  has been controlled to push annular brace  100  out from deployment catheter  150  so that bottom gripping wings  103  and  104  protrude between anterior and posterior leaflets  44  and  45  ( FIGS. 1 and 2A ) in a region of commissure  46 -C to below the leaflets, and recess  106  cups the annulus. The position of bottom gripping wings  103  and  104  in  FIG. 5B  relative to deployment catheter  150  is similar to that shown in  FIG. 4G . Having been released from deployment catheter  150 , gripping wings  103  and  104  bend apart to their respective deployment locations under annulus  46  to the left and right respectively of commissure  46 -C as schematically shown in  FIG. 5C . In  FIG. 5D  push road  152  has pushed annular brace  100  completely out of deployment catheter  150 , top gripping wings  101  and  102  have bent to their deployed configuration opposite gripping wings  103  and  104  respectively and deployment catheter  150  has been removed from left atrium  41 . Top and bottom gripping wings  101  and  103  sandwich, grip, and anchor to a region of annulus  46  between them and top to the left of commissure  46 -C and bottom gripping wings  102  and  104  sandwich, grip, and anchor to a region of annulus  46  between them to the right of commissure  46 -C. Annular brace  100  is fully deployed and mounted to annulus  46  at commissure  46 -C. 
         [0062]      FIG. 6  schematically shows a view from the atrial side of a mitral valve  243  comprising leaflets  244  and  245  that are supported by an annulus  246  shown shaded and operate to coapt along a seam  247  that extends between commissures  248  and  249 . Function of mitral valve  243  is assumed to be compromised by prolapse of leaflets  244  and  245  into the atrium. To alleviate prolapse, in accordance with an embodiment of the invention, an annular brace  100  is mounted to annulus  246  at each commissure  248  and  249  of the valve, and leaflet restraining struts  251  and  252  are mounted to braces  100  to restrain motion of the leaflets into the atrium. 
         [0063]      FIGS. 7A-7C  schematically illustrate construction of an annular wireframe brace  200 , in accordance with an embodiment of the invention. 
         [0064]      FIG. 7A  schematically shows a wireform “blank”  190  after the wireform has optionally been cut from a sheet of a suitable deformable biocompatible material or formed from a wire of such a material, in accordance with an embodiment of the invention. Wireform blank  190  optionally comprises two bridge wires  205  that connect wire-loops  191  and  192 . Wire-loop  191  comprises top and bottom wire gripping wings  201  and  203  respectively. Wire-loop  192  comprises top and bottom wire gripping wings  202  and  204  respectively. Bending wire-loops  191  and  192  in regions where the wire-loops meet bridge wires  205  as schematically shown in  FIG. 7B  produces wireframe annular brace  200  in a delivery configuration.  FIG. 7C  schematically shows wireframe annular brace  200  in a deployed configuration. It is noted that wireform blank  190  may be folded and conditioned to provide a wireframe annular brace  220  shown in  FIG. 7D  in which top wire gripping wings are gripping wings  202  and  204  and bottom gripping wings are gripping wings  201  and  203 . Wireform annular brace  220  is shown in a deployed configuration in  FIG. 7D . 
         [0065]    Similarly, to annular brace  100  an annular wire brace in accordance with an embodiment of the invention may be formed having gripping teeth and stabilizer teeth. And whereas wire-loops  191  and  192  are shown as simple wire loops formed from straight wire sections, wire-loops in accordance with an embodiment of the invention may be formed from wavy wire sections or may comprise a wire mesh. 
         [0066]    In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb. 
         [0067]    Descriptions of embodiments of the invention in the present application are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments utilize only some of the features or possible combinations of the features. Variations of embodiments of the invention that are described, and embodiments of the invention comprising different combinations of features noted in the described embodiments, will occur to persons of the art. The scope of the invention is limited only by the claims.
A brace for mounting to an annulus of a cardiac valve, the brace comprising: first and second bottom gripping wings for gripping the annulus; first and second top gripping wings for gripping the annulus; and a support bridge that connects the top wings to the bottom wings; wherein the brace is deformable from a delivery configuration to a deployed configuration and in the delivery configuration the top wings are oriented substantially back to back along an axis and the bottom wings are oriented substantially back to back along the same axis, and in the deployed configuration the first top and bottom gripping wings face each other to grip the annulus between them and the second top and bottom gripping wings face each other to grip the annulus between them.