described herein is a flexible , self - orienting cardiac valve prosthesis configured to be delivered through minimally invasive techniques . the prosthesis can include a proximal anchor ( e . g ., configured to be placed in the ventricle ), a distal anchor ( e . g ., configured to be placed in the atrium ), a central portion or column between the anchors , a plurality of struts extending distally ( e . g ., into the ventricle ), and a plurality of leaflets attached to the struts . the prosthesis can be self - expanding , such as be made of super elastic nickel titanium ( nitinol ). in some embodiments , the prosthesis can be made of woven stranded nitinol . the prosthesis described herein can be delivered to a cardiac valve orifice , such as the mitral valve , by using minimally invasive techniques to access cardiac valves through small incisions in the patient &# 39 ; s body , passing the prosthesis through the apex of the heart , through the aorta via femoral artery access , through the aorta via an intercostal puncture , through the vena cava via femoral vein access , through the vena cava via jugular access , and through the venous system into the left heart via a transseptal puncture . the flexible prosthesis can be folded and compressed to fit within a delivery tube . the delivery tube can used to position the prosthesis at the treatment site , and if necessary , re - sheath , reposition , and re - deploy the device . during deployment , the distal anchor can be deployed first in a cardiac chamber , such as the ventricle , and retracted to a seated position against the valve orifice , such as the mitral valve orifice . then the center column and proximal anchor may then be deployed in another cardiac chamber , such as the atrium , sandwiching the valve orifice securely between the anchors in opposing cardiac chambers . embodiments of the invention are designed to secure the valve prosthesis in the orifice by applying a radial force from the center column structure of the prosthesis outward against the cardiac orifice and by sandwiching the cardiac orifice between distal and proximal anchors that are larger in diameter than the orifice . further engagement between the prosthesis and tissue may be added by securing small , curved wire hooks into the sub - structures of the valve prosthesis . fig1 a - 1e show an exemplary embodiment of a valve prosthesis 100 . the valve prosthesis includes a proximal anchor 2 , a distal anchor 3 , and a central portion 4 therebetween . a central opening 15 extends through the center of the prosthesis 100 . the central portion 4 can substantially trace the perimeter of the central opening 15 while each anchor 2 , 3 can extend outwardly therefrom in an annular shape . the proximal anchor 2 , distal anchor 3 , and central portion 4 can be formed of wire , such as nitinol wire rope . each anchor 2 , 3 can include a first outer frame 122 , 133 and a second outer frame 222 , 233 , respectively . in one embodiment , the proximal anchor 2 and distal anchor 3 can be substantially parallel to one another . an exemplary proximal anchor 2 is shown in fig1 c . the first outer frame 122 can sit proximal to the second outer frame 222 , and the first outer frame 122 can sit in a plane substantially parallel to the plane of the second outer frame 222 . further , each frame 122 , 222 can include a plurality of arcs 111 , 211 ( which can also be referred to as arcuate portions , curved portions , or petals ), such as between 4 and 10 or between 5 and 8 arcs , joined together at joints 16 , 26 , respectively . for example , outer frame 122 can include six arcs 111 a , b , c , d , e , f while outer frame 222 can also include six arcs 211 a , b , c , d , e , f . the arcs 111 of the outer frame 122 can be connected together , and the arcs 211 of the outer frame 222 can be connected together , so as to form a substantially circular outer perimeter for each of the frames 122 , 222 . each joint 16 , 26 between neighboring arcs 111 or 211 can be , for example , a crimp that crimps adjacent arcs ( e . g ., 111 a and 111 b ) to one another . as shown in fig1 c , the outer frames 122 , 222 can be positioned relative to one another such that the arcs 111 , 211 are out of phase relative to one another . for example , the arcs 111 can be approximately 90 degrees out of phase relative to the arcs 211 . that is , the arcs 111 of the first outer frame 122 can overlap with the arcs 211 of the second outer frame 222 such that , for example , a single arc 111 a of the first outer frame 122 overlaps with half of two underlying arcs 211 f , 211 a of the second outer frame 222 . in some embodiments , only some arcs are out of phase with one another while other arcs are in - phase with one another . the second outer frames 133 , 233 can likewise include arcs as described with respect to the first outer frame 122 , 222 . as shown in fig1 a and 1e , the first outer frame 122 , 133 and the second outer frame 222 , 233 of each anchor 2 , 3 can be connected to one another through the central portion 4 . the central portion 4 can extend from the crimps 16 , 26 of the proximal anchor 2 to the corresponding crimps of the distal anchor 3 . the central portion 4 can include substructures or wire segments 44 that form a pattern , such as a hexagonal pattern ( see fig1 e ). for example , two wire segments 44 a , b of the central portion 4 can extend at an angle from the crimp 16 a ( see fig1 d , 1 e ), such as to form an angle of approximately 120 degrees relative to one another . each of the wire segments 44 a , b can then meet adjacent wire segments within the central portion 4 ( e . g ., segment 44 b meets segment 44 c ). the adjacent wire segments ( e . g ., 44 b and 44 c ) can then be joined together at a joint 46 ( e . g ., joint 46 a ). the joint 46 a can form a column substantially parallel to a central axis 110 of the prosthesis 100 . this pattern can extend throughout the entire prosthesis to form a number of joints 46 , such as twelve joints 46 . the joints 46 can not only fix the position of the outer frames of a single anchor together , but also fix the proximal and distal anchors 2 , 3 together . the hexagonal structure of the segments 44 and joints 46 can advantageously provide radial and vertical strength as well as stability to the prosthesis 100 . in some embodiments ( as shown in fig1 d ), parts of the central portion 4 can be formed of the same wire or wire rope as the outer frames of the anchors 2 , 3 and / or the outer frames of the anchors 2 , 3 can be formed of the same wire or wire rope as one another . for example , two single strands of wire , such as two 22 - inch long strands of wire , can be used to form the anchors 2 , 3 and the central portion 4 . as shown in fig1 d and 1e , a single strand 191 ( darkened in the picture relative to the opposite strand 193 for clarity ) can form an arc 111 a ( see fig1 d ) of the first outer frame 122 of proximal anchor 2 , extend through a joint 16 a to form wire segment 44 b of the central portion 4 , extend through joint 46 a to form wire segment 44 d ( see fig1 d ), then form an arch of the second outer frame 233 , extend through another joint to form wire segment 44 e ( see fig1 d ), extend around in a similar fashion to form wire segment 44 f ( see fig1 d ), and continue winding in a similar fashion until all of the outer frames 122 , 233 have been formed from the single strand 191 . the ends of the strand 191 can then be attached to one another , such as through splicing crimps , butt joint crimps , welding , riveting , or weaving . the second strand 193 can be wound similarly to form the second outer frame 222 of the proximal anchor 2 and the first outer frame 133 of the distal anchor 3 . by joining the first outer frame 122 , 133 to the second outer frame 222 , 233 of each anchor 2 , 3 , as described above , the arcs of each outer frame can be movable relative to one another . for example , the arc 111 a can be movable relative to the arcs 211 f , 211 a that it overlaps ( see fig1 c ). that is , the outer perimeter of the arc 111 a can flex along the central axis and / or translate relative to the arcs 211 f , 211 a ( while the inner perimeter is fixed at the joints 46 ). advantageously , the large arc structure of the anchors can provide flexibility and compliance for the portions of the prosthesis intended to be placed in the chambers of the heart . in contrast , in the stiffer tissue of the valve orifice , the hexagonal sub - structures of the central portion can provide higher radial stiffness and strength . further , by using wire rope , the prosthesis can advantageously be foldable and strong while the individual fibers , because they are small in diameter , can maintain resistance to fatigue and fracture . in some embodiments , the two frames of a single anchor can be formed of wire rope of opposite lays . for example , the wire of one frame ( e . g . strand 193 ) can be made of a rope twisted to the left while the wire of another frame ( e . g . strand 191 ) can be made of a rope twisted to the right . using wires of opposite lays can allow the wires to compensate for one another as they compress , thereby maintaining relative positioning during expansion or contraction / folding of the device ( as opposed to twisting of the entire device ). various possibilities for winding the wire rope are shown in fig8 a - 9b . as shown in fig1 a and 1e , struts 5 can extend distally from the distal anchor 3 and / or the central portion 4 and be configured to hold leaflets ( shown in fig2 a - 2c ). the struts 5 can be formed , for example , of wire rope . further , in one example , each strut 5 can include a plurality of wire components 55 , such as three wire components 55 . each of the three wire components 55 of a single strut 5 can extend from neighboring joints 46 and come together at a joint 56 , thereby forming triangular struts 5 . in some embodiments , additional supporting structures , such as tubes , can be placed over or around the struts to increase the stiffness . the triangular struts 5 can provide vertical strength and lateral flexibility . in one embodiment , there can be three struts 5 located approximately 120 degrees away from one another around the circumference of the prosthesis 100 . the joints 56 can be , for example , crimps . as shown in fig1 a and 1e , in one embodiment , the center strut member 55 a of a three - strut support can be substantially straight and connected to two outside , curved strut members 55 b , 55 c to form a structure comprised of two substantially triangular sub - structures , each with the center member as a common triangle leg . this center member may be made of a thin element of material which provides strength in tension as the pressurized leaflets are pushed toward the center of the valve , while providing flexion in compression to allow the valve prosthesis to be folded for delivery and to allow the prosthesis to conform to tissue when placed within the heart . the various crimps used for the joints of the prosthesis 100 may be made of a suitable implantable material , such as platinum , tantalum , or titanium . further , in place of crimps , braids , weaves , or welding can be used . referring to fig2 a - 2c , the valve prosthesis 100 can include integral valve leaflets 511 attached , such as sewn , to the struts 5 . there can be three integral valve leaflets 511 , and the leaflets 511 can form a pressure actuated valve that provides uni - directional flow occlusion when the prosthesis 100 is implanted in a valve orifice . the leaflets can be constructed of bio - materials , such as bovine or porcine pericardium , or polymer materials . in one embodiment ( shown in fig2 b - 2c ), the proximal anchor 2 can include a cover or skirt 12 thereon or therearound formed of a biomaterial or thin polymer material . the skirt 12 can advantageously help seal the prosthesis 100 against the cardiac tissue when implanted . the prosthesis 100 can be configured to be placed in a cardiac valve orifice such that the central portion 4 lines the orifice while the proximal and distal anchors 2 , 3 sit within the chambers of the heart and pinch tissue of the orifice therebetween . in some embodiments , the prosthesis 100 can be sized and configured for use in the mitral valve orifice ( shown in fig6 d ). referring to fig3 a - 3b , to ensure that the prosthesis 100 fits properly within the valve , the diameter d o of the central opening 15 can be greater than a length l of the device when fully expanded . for example , the ratio d o / l can be greater than or equal to 1 . 1 , such as greater than or equal to 1 . 2 or greater than or equal to 1 . 3 . further , the ratio d o / l can be less than 2 . 0 . in one embodiment , the diameter d o is between 25 mm and 40 mm , such as approximately 28 mm . further , in one embodiment , the length l is less than or equal to 22 mm , or less than or equal to 20 mm , such as approximately 14 mm . further , to ensure that the proximal and distal anchors have enough tissue to grab onto , a ratio of the outer diameter of the anchors , d t , to the length l can be greater than or equal to 2 . 0 . in one embodiment , an outer diameter of anchors , d t , can be at least 38 mm , such as greater than or equal to 40 mm . further , in one embodiment , the anchors can extend out at a radius r a of greater than 10 mm , such as approximately 12 mm . finally , a ratio d o to a length of the struts l s can be approximately 1 . 5 to 3 . 0 , such as 2 . 1 . a radio of d o / l s within this range can advantageously ensure that there is enough leaflet material to allow the leaflets to oppose and seal under stress while maintaining a small enough length to fit properly within the valve . in one embodiment , the struts have a length l s of between 8 and 16 mm , such as approximately 14 mm . further , l c can be approximately 4 - 10 mm , such as 6 mm . in one exemplary embodiment , d o is 28 mm , r a is 12 mm , l c is 6 mm , l s is 14 mm , d t is 40 mm , and l 1 is 14 mm . fig4 a - 4b show a closed delivery device 200 for delivery of a valve prosthesis 100 . the delivery device 200 can include an outer sheath 13 and a multi - lumen central longitudinal structure 17 extending therethrough . the valve prosthesis 100 is configured to fit over the central longitudinal structure 17 and within the sheath 13 so as to be fully encapsulated within the delivery device 200 . the lumens in the longitudinal structure 17 can be tubular structures 357 ( see fig4 b and 5c ). each tubular structure 357 can include a side lumen 355 ( see fig4 b and 10a ) therein , i . e ., an aperture disposed on a radial outer portion of the tubular wall . the tubular structures 357 can contain retention members 19 that bind the proximal anchor 2 of the valve prosthesis tightly to the longitudinal structure 17 . the retention members 19 can be made , for example , of a strong , flexible material such as nitinol , nitinol wire rope , or liquid crystal polymer fiber , such as vectran ®. there can be various numbers of retention wires and corresponding tubes 357 and lumens , such as between 4 and 20 or between 6 and 12 retention wires and corresponding tubes / lumens . in one embodiment , there are six retention wires and lumens . in another , there are twelve retention wires and lumens . the delivery device 200 includes a central lumen 15 running therethrough ( i . e ., through the central longitudinal structure 17 ) configured to pass a standard cardiac guidewire 16 . the guidewire 16 may be used to provide a safe pathway for getting the device 100 to the anatomical target . the delivery device 200 further includes a tapered tip 14 to provide a gradual , atraumatic transition from the guidewire to the outer sheath 13 of the delivery device 200 . in some embodiments , the delivery device 200 can be adapted to specific delivery paths and cardiac structures by being provided with pre - shaped bends in the outer sheath 13 . in some embodiments , the delivery device 200 may contain pull - wires integral with the outer wall that may be tensioned to articulate and bend the outer sheath 13 . the pull wires may terminate at the tip of the device to provide a bend starting at the distal tip or may terminate along the longitudinal shaft of the device to provide a more proximal bend location . fig5 a - 5d show a multi - stage delivery system for a cardiac valve prosthesis ( with the valve leaflets omitted from the drawings for clarity ). fig5 a shows the delivery device 200 having a handle 300 connected thereto to control the delivery of a prosthesis loaded within the device . fig5 b and 5c shows the prosthesis 100 partially deployed . that is , as the sheath 13 is pulled back with a lever 301 on the handle 300 , the distal anchor 3 ( previously collapsed into the sheath 11 with the peaks of the arcs extending distally ) pops open . the proximal anchor 2 , in turn , can remain connected to the delivery device 100 via the retention wires 19 . that is , the retention wires 19 can pass through the multi - lumen central structure 17 , through the arcs of the outer frame 122 , 222 at apertures 355 , and back into lumens of the structure 17 . referring to fig1 a and 12a , in one embodiment , the proximal anchor 2 can be connected to the retention wires 19 such that neighboring arcs 111 a , 211 a of the proximal anchor 2 extend over neighboring retention wires 19 a , 19 b . in other embodiments ( as shown in fig1 b ), two neighboring arcs 111 a , 211 a can extend over a single retention wire 19 a . referring back to fig5 b and 5c , as the retention wires 19 are pulled tight , the peaks of the arcs of the proximal anchor 2 will be pulled proximally , thereby causing the proximal anchor 2 to fold or cinch up to form a funnel shape at the proximal end of the distal anchor 3 ( crimps 16 , 26 of the proximal anchor 2 can be seen ). to expand the proximal anchor 2 , the wires 19 can either be withdrawn or loosened ( such as with a lever 303 on the handle ), thereby allowing the proximal anchor 2 to self - expand into place , as shown in fig5 d . referring to fig1 a - 10b , in some embodiments , the wires 19 a can be withdrawn completely , thereby allowing the proximal anchor 2 to expand . in another embodiment , shown in fig1 a - 11b , the retention wires 19 can be formed of loops that , when loosened , i . e . pushed distally , allow the distal anchor 2 to expand without releasing the anchor 2 . by using such a mechanism , the proximal anchor can be resheathed and moved ( by retightening the retention members 19 ) if necessary . a mechanism on the handle can then be used to release the retention members 19 entirely . referring to fig6 a , to deploy the valve prosthesis 100 in a valve ( such as the mitral valve ), the guidewire 16 and delivery device 200 can be inserted through the native valve . referring to fig6 b , as the outer sheath 13 of the device 200 is retracted relative to the central longitudinal structure 17 , the distal anchor 3 of the valve prosthesis is exposed and self - expands ( such as into the left ventricle ). once expanded , the distal anchor 3 may be retracted proximally against the distal - facing tissue of the cardiac chamber around the orifice , providing positive tactile feedback that the distal anchor 3 is oriented and positioned properly against the distal wall of the cardiac orifice . further retraction of the sheath 13 exposes the central portion 4 of the valve prosthesis , allowing the central portion 4 to radially expand against the inner wall of the cardiac orifice . referring to fig6 c , to expand the prosthesis 100 on the other side of the cardiac orifice ( i . e ., in the left atrium ), the central retention members 19 of the delivery device can be withdrawn or loosened as described above , thereby expanding the proximal anchor 2 . the expanded proximal anchor 2 provides a second backstop to the valve prosthesis 100 , allowing the prosthesis 100 to sandwich the valve orifice , such as the mitral valve orifice between the proximal and distal anchors 2 , 3 . as the device 100 expands , it foreshortens , moving the proximal anchor 2 and distal anchor 3 toward each other to provide a compressive force on tissue surrounding the cardiac orifice , such as the valve annulus . thus , in one example , as shown in fig6 d , the prosthesis can be delivered into the mitral valve orifice such that the distal anchor 3 sits within the left ventricle while the proximal anchor 2 sits within the left atrium . the struts 5 and leaflets 511 can extend distally into the left ventricle . tissue of the mitral valve annulus can be captured between the anchors 2 , 3 . further , the size of the prosthesis 100 can be such that the anchors 2 , 3 extend within the chambers of the heart and much wider than the diameter of the orifice itself , thereby allowing for strong tissue capture and anchoring . in some embodiments , placement of the prosthesis can move the existing leaflets valves out of the way . in some embodiments , as described above , the valve prosthesis 100 can be repositioned using the delivery device 200 . that is , by pulling on the retention wires 19 , the proximal anchor 2 can be cinched back down with the proximal arcs extending proximally . the distal anchor 3 can be collapsed into the sheath ( with the arcs extending distally ) either by pulling proximally on the prosthesis 100 or pushing the sheath 13 distally . use of an alternative delivery device is shown in fig1 . as shown in fig1 , rather than including multiple retention wires , the delivery device can include a single elongate member 96 over which all of the arcs 111 , 211 of the proximal anchor 2 are placed . fig7 shows an embodiment of the valve prosthesis 199 where retention hooks 21 are built into the device . the hooks 21 extend from toward the center of the device from the joints ( e . g ., crimps ) of the distal anchor 3 . the hooks may be made of nitinol and are curved so that as the distal anchor 3 is drawn toward the center longitudinal member 17 of the delivery device 200 , the hooks flatten and collapse , allowing the outer sheath 13 of the delivery device 200 to slide smoothly over the hooks 21 . as the outer sheath 13 is removed from the valve prosthesis 100 during delivery and the distal anchor 3 of the valve prosthesis opens , the hooks 21 expand into the tissue of the cardiac orifice . in embodiment , the hooks 21 are only located on the distal anchor 3 , as the distal anchor 3 , when located on the ventricular side of the aorta , undergoes the highest pressure . in other embodiments , the hooks 21 are located on the proximal anchor 2 and / or the central portion 4 . in one embodiment , small hooks in the distal anchor 3 may be used to grip the valve leaflets . as the distal anchor 3 is retracted from the ventricle toward the mitral valve annulus , the hooks can pull the leaflets into a folded position just under the ventricular side of the mitral annulus . while preferred embodiments of the present invention have been shown and described herein , it will be obvious to those skilled in the art that such embodiments are provided by way of example only . numerous variations , changes , and substitutions will now occur to those skilled in the art without departing from the invention . it should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention . it is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby .
a method of delivering a prosthetic mitral valve includes delivering a distal anchor from a delivery sheath such that the distal anchor self - expands inside a first heart chamber on a first side of the mitral valve annulus , pulling proximally on the distal anchor such that the distal anchor self - aligns within the mitral valve annulus and the distal anchor rests against tissue of the ventricular heart chamber , and delivering a proximal anchor from the delivery sheath to a second heart chamber on a second side of the mitral valve annulus such that the proximal anchor self - expands and moves towards the distal anchor to rest against tissue of the second heart chamber . the self - expansion of the proximal anchor captures tissue of the mitral valve annulus therebetween .