Abstract:
Artificial valves for use as a venous valve or a heart valve are disclosed. The valve includes a frame including a platform and a valve material coupled to the frame. The valve material is a plurality of filaments or a flap. The valve material is coupled to the frame such that in response to a force in a first direction, e.g. blood flow, the valve material extends in the direct of the force to allow blood to flow past the valve material. In absence of the force in the first direction, the valve material rests against the platform to block blood flow in a direction opposite the first direction.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to one-way venous and aortic valves and methods for percutaneously delivery and deployment of such valves. 
       BACKGROUND 
       [0002]    Venous valves are found within native venous vessels and are used to assist in returning blood back to the heart in an antegrade direction from all parts of the body. The venous system of the leg for example includes the deep venous system and the superficial venous system, both of which are provided with venous valves that are intended to direct blood toward the heart and prevent backflow or retrograde flow, which can lead to blood pooling or stasis in the leg. Incompetent valves can also lead to reflux of blood from the deep venous system to the superficial venous system and the formation of varicose veins. Superficial veins, which include the greater and lesser saphenous veins, have perforating branches in the femoral and popliteal regions of the leg that direct blood flow toward the deep venous system and generally have a venous valve located near the junction with the deep system. Deep veins of the leg include the anterior and posterior tibial veins, popliteal veins, femoral veins, and iliac veins. Deep veins are surrounded in part by musculature tissue that assists in generating flow due to muscle contraction during normal walking or exercising. Veins in the lower leg have a static pressure while standing of approximately 80-90 mm Hg that may reduce during exercise to 60-70 mm Hg. Despite exposure to such pressures, the valves of the leg are very flexible and can close with a pressure drop of less than one mm Hg. 
         [0003]      FIGS. 1A-1B  are schematic representations of blood flow through a healthy native valve  104  within a vein  100 . Venous valve  104  controls blood flow through lumen  102  of vein  100  via leaflets  106 ,  108 . More particularly, venous valve  104  opens to allow antegrade flow  112  through leaflets  106 ,  108  as shown in  FIG. 1A . Venous valve  104  closes to prevent backflow or retrograde flow  114  through leaflets  106 ,  108  as shown in  FIG. 1B . 
         [0004]    Veins typically in the leg can become distended from prolonged exposure to excessive pressure and due to weaknesses found in the vessel wall causing the natural venous valves to become incompetent leading to retrograde blood flow in the veins. Such veins no longer function to help pump or direct the blood back to the heart during normal walking or use of the leg muscles. As a result, blood tends to pool in the lower leg and can lead to leg swelling and the formation of deep venous thrombosis and phlebitis. The formation of thrombus in the veins can further impair venous valvular function by causing valvular adherence to the venous wall with possible irreversible loss of venous function. Continued exposure of the venous system to blood pooling and swelling of the surrounding tissue can lead to postphlebitic syndrome with a propensity for open sores, infection, and may lead to possible limb amputation. 
         [0005]    Chronic Venous Insufficiency (CVI) occurs in patients that have deep and superficial venous valves of their lower extremities (below their pelvis) that have failed or become incompetent due to congenital valvular abnormalities and/or pathophysiologic disease of their vasculature. As a result, these patients suffer from varicose veins, swelling and pain of the lower extremities, edema, hyper pigmentation, lipodermatosclerosis, and deep vein thrombosis (DVT). Such patients are at increased risk for development of soft tissue necrosis, ulcerations, pulmonary embolism, stroke, heart attack, and amputations. 
         [0006]      FIG. 2  is a schematic representation of blood flow through an incompetent venous valve. Backflow or retrograde flow  114  leaks through venous valve  104  creating blood build-up that eventually may destroy the venous valve and cause a venous wall bulge  110 . More specifically, the vessel wall of vein  100  expands into a pouch or bulge, such that the vessel has a knotted appearance when the pouch is filled with blood. The distended vessel wall area may occur on the outflow side of the valve above leaflets  106 ,  108  as shown in  FIG. 2 , and/or on the inflow side of the valve below leaflets  106 ,  108 . After a vein segment becomes incompetent, the vessel wall dilates and fluid velocity there through decreases, which may lead to flow stasis and thrombus formation in the proximity of the venous valve. 
         [0007]    Repair and replacement of venous valves presents a formidable problem due to the low blood flow rate found in native veins, the very thin wall structure of the venous wall and the venous valve, and the ease and frequency of which venous blood flow can be impeded or totally blocked for a period of time. Surgical reconstruction techniques used to address venous valve incompetence include venous valve bypass using a segment of vein with a competent valve, venous transposition to bypass venous blood flow through a neighboring competent valve, and valvuloplasty to repair the valve cusps. These surgical approaches may involve placement of synthetic, allograft and/or xenograft prostheses inside of or around the vein. However, such prostheses have not been devoid of problems leading to thrombus and/or valve failure due to leaflet thickening/stiffening, non-physiologic flow conditions, non-biocompatible materials and/or excessive dilation of the vessels with a subsequent decrease in blood flow rates. 
         [0008]    The aortic valve is located at the intersection of the left ventricle of the heart and the ascending aorta. During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing blood to exit the left ventricle into the aorta. When ventricular systole ends, pressure in the left ventricle rapidly drops. When the pressure in the left ventricle decreases, the aortic pressure forces the aortic valve to close. 
         [0009]      FIGS. 3A-3B  are schematic representations of blood flow through a healthy aortic valve  304  at the intersection of aorta  302  and left ventricle  306 . Aortic valve  304  controls blood flow from left ventricle  306  to aorta  302 . More particularly, aortic valve  304  opens to allow antegrade flow  312  through aortic valve  304  as shown in  FIG. 3A . Aortic valve  304  closes to prevent backflow or retrograde flow  314  through aortic valve  304  as shown in  FIG. 3B . 
         [0010]      FIG. 5  is a schematic illustration of the junction between the aorta  302  and the heart. The aortic root  318  is the portion of the left ventricular outflow tract which supports the leaflets  334  (shown in  FIG. 6 ) of the aortic valve  304 . The aortic root  318  may be delineated by the sinotubular junction  336  distally and the bases of the valve leaflets  334  proximally. The aortic root  318  comprises the sinuses  332 , the valve leaflets  334 , the commissures  340 , and the interleaflet triangles (not shown). The annulus  338  is the area of collagenous condensation at the point of leaflet attachment. The annulus  338  comprises a dense fibrous ring attached either directly or indirectly to the atrial or ventricular muscle fibers. 
         [0011]    Aortic insufficiency (AI), also called aortic regurgitation, occurs when the aortic valve does not close completely when pressure in the left ventricle drops at the end of ventricular systole. Such a failure to close causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle of the heart. This means that some of the blood that was already ejected from the heart is regurgitated back into the heart. The percentage of blood that regurgitates back through the aortic valve due to AI is known as the regurgitant fraction. Since some of the blood that is ejected during systole regurgitates back into the left ventricle during diastole, there is decreased effective forward flow in AI. Aortic insufficiency causes both volume overload (elevated preload) and pressure overload (elevated afterload) of the heart. 
         [0012]      FIG. 4  is a schematic representation of blood flow through an incompetent aortic valve  304 . Backflow or antegrade flow  314  leaks through aortic valve  304  such that blood regurgitates back into the left ventricle  306 . 
         [0013]    Aortic insufficiency can be due to abnormalities of either the aortic valve or the aortic root. The surgical treatment of choice at this time is an aortic valve replacement. This is currently an open-heart procedure, requiring the individual to be placed on cardiopulmonary bypass. Further, any replacement or treatment of the aortic valve must take into account the coronary arteries. The coronary arteries (left and right) (not shown) originate from the aortic root  318  (more particularly the sinuses  332 ), immediately above the aortic valve. The coronary arteries supply oxygen rich blood to the muscle tissue of the heart (the myocardium). The junction of the coronary arteries with the sinuses is called the coronary ostia. The left coronary ostium  350  and right coronary ostium  352  are shown in  FIGS. 9B ,  13 A, and  13 B. The coronary ostia cannot be blocked by the replacement valve. 
         [0014]    Similarly, pulmonary valve  310  (shown in  FIGS. 3A-3B ) controls blood flow from the right ventricle  311  to the main pulmonary artery  308 , and eventually to the lungs. More particularly, pulmonary valve  310  opens to allow antegrade flow through pulmonary valve  310 . Pulmonary valve  310  closes to prevent backflow or retrograde flow through pulmonary valve  310  back into right ventricle  311 . Pulmonary valve insufficiency or regurgitation occurs when the pulmonary valve  310  does not close properly after the right ventricle  311  has finished its pumping cycle. Excess blood therefore makes the right ventricle  311  work harder than normal. 
         [0015]    As with aortic valve insufficiency, pulmonary valve insufficiency can be due to abnormalities of either the pulmonary valve or the annulus. The surgical treatment of choice at this time is a pulmonary valve replacement. This is currently an open-heart procedure, requiring the individual to be placed on cardiopulmonary bypass. 
         [0016]    Throughout this specification, references to a heart valve, aortic valve, or pulmonary valve can apply equally to both the aortic valve and the pulmonary valve, except where specifically noted. Thus, structures described below for the aortic valve apply equally to the pulmonary valve. 
         [0017]    In view of the foregoing, there is still a need for methods and apparatus to restore normal venous circulation to patients suffering from venous valve insufficiency and normal circulation to the aorta to patients suffering from aortic valve insufficiency, wherein the methods and apparatus may be used in percutaneous, minimally invasive procedures. 
       BRIEF SUMMARY OF THE INVENTION 
       [0018]    Embodiments hereof are directed to an artificial valve for use as a venous valve or an aortic valve. In one embodiment, the valve includes a frame including a platform and a valve material coupled to the frame. The valve material in one embodiment is a plurality of filaments. In another embodiment, the valve material is a flap. The valve material is coupled to the frame such that in response to a force in a first direction, e.g. antegrade blood flow, the valve material extends in the direction of the force to allow blood to flow past the valve material. In absence of the force in the first direction, the valve material rests against the platform to block blood flow in a direction opposite the first direction, or retrograde blood flow. The embodiment with the flap may include slits in the flap or a shape memory material in the flap. 
         [0019]    In a method of delivering an artificial one-way valve to a target location, the one-way valve is disposed in a catheter in a compressed configuration. Percutaneous access in obtained to a vessel to reach the target location. A guidewire is tracked to the target location. The guidewire is backloaded into the catheter and the catheter is advanced over the guidewire to the target location. The valve is then released from the catheter. The valve can be delivered to the location of an incompetent venous valve or an incompetent aortic valve. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0020]    The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. The drawings are not to scale. 
           [0021]      FIGS. 1A-1B  are schematic representations of blood flow through a healthy valve within a vein. 
           [0022]      FIG. 2  is a schematic representation of blood flow through an incompetent valve within a vein. 
           [0023]      FIGS. 3A-3B  are schematic representations of blood flow through a healthy aortic valve. 
           [0024]      FIG. 4  is a schematic representation of blood flow through an incompetent aortic valve. 
           [0025]      FIG. 5  is a cross-sectional illustration of the ascending aorta and the aortic valve. 
           [0026]      FIG. 6  is a schematic illustration of an aortic valve. 
           [0027]      FIG. 7  is a schematic representation of a one-way valve in accordance with an embodiment hereof. 
           [0028]      FIGS. 8A-8B  are schematic representations of the one-way valve of  FIG. 7  located in a vein at the location of a venous valve. 
           [0029]      FIGS. 9A-9B  are schematic representations of the one-way valve of  FIG. 7  located at the aortic valve. 
           [0030]      FIGS. 10A-10B  are schematic representations of configurations of the filaments of the valve of  FIG. 7 . 
           [0031]      FIGS. 11A-11B  are schematic representations of a one-way valve in accordance with another embodiment hereof. 
           [0032]      FIGS. 12A-12B  are schematic representations of the one-way valve of  FIGS. 11A-11B  in a vein at the location of a venous valve. 
           [0033]      FIGS. 13A-13B  are schematic representations of the one one-way valve of  FIGS. 11A-11B  located at the aortic valve. 
           [0034]      FIG. 14  is a schematic representation of a one-way valve in accordance with another embodiment hereof. 
           [0035]      FIGS. 15A-15B  are schematic representations of a one-way valve in accordance with another embodiment hereof. 
           [0036]      FIG. 16A-16B  are schematic representations of a one-way valve in accordance with another embodiment hereof. 
           [0037]      FIG. 17  is a schematic representation of a delivery catheter for a one-way valve. 
           [0038]      FIGS. 18-20  are schematic representations of a method a delivering a one-way valve to replace an incompetent valve. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    Specific embodiments hereof are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician. 
         [0040]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Although the description of the invention is in the context of treatment of blood vessels such as the deep and superficial veins of the leg, the invention may also be used in any other body passageways where it is deemed useful. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
         [0041]      FIG. 7  is a schematic representation of one-way valve  400  in accordance with an embodiment hereof. Valve  400  includes a coil or frame  402  and a multitude of filaments  403  or ribbons coupled to the frame  402 . Frame  402  is preferably formed from a shape memory material, such as a nickel-titanium alloy (Nitinol), such that frame  402  is self-expanding. It would be understood by those skilled in the art that frame  402  can be made of other materials used, for example, in stents, and may be balloon expandable. In another example, frame  402  may be made from a metal-to-metal composite with tantalum as the core material and Nitinol as the cover or tube material, such as available from Fort Wayne Metals in their DFT® wire. Such a frame material would permit enhanced visualization of frame  402  due to the tantalum core. 
         [0042]    In the embodiment shown in  FIG. 7 , frame  402  is a wire formed into a tubular coil. In  FIG. 7  (and  FIGS. 8-16 ), the frame is shown in its expanded configuration. A portion of frame  402  includes a platform  408 . As shown in  FIG. 7 , platform  408  is formed by the nitinol wire extending in a circular, or spiral, pattern towards a longitudinal axis  410  of frame  402 . Filaments  403  are coupled to frame  402  at platform  408 . When blood flows in the direction of arrow  412 , filaments  403  extend in the direction of flow, as shown in  FIGS. 8A and 9A . When there is a pressure drop such that blood does not flow in the direction of arrow  412 , filaments  403  rest against platform  408 , as shown in  FIGS. 8B and 9B , to create a barrier to retrograde blood flood. Filaments  403  may be made of biocompatible, non-thrombotic materials such as, but not limited to, Polyethylene terephthalate (Dacron®) and expanded polytetrafluoroethylene (ePTFE). 
         [0043]      FIGS. 8A-8B  are schematic illustrations of valve  400  installed in a vein  100  at the location of a venous valve  104 .  FIGS. 8A-8B  show frame  402  in its expanded configuration. Frame  402  is installed in vein  100  such that frame  402  holds venous valve  104  in an open configuration.  FIG. 8A  shows filaments  403  extended in the direction of blood flow shown by arrow  412 , permitting blood to flow back towards the heart.  FIG. 8B  shows filaments  403  resting against platform  408  of frame  402  to prevent retrograde blood flow  414 . When installed in a vein as shown in  FIGS. 8A-8B , the length of filaments  403  is preferably 0.5 to 1.0 times the diameter of vein  100 . 
         [0044]      FIGS. 9A-9B  are schematic illustrations are schematic illustrations of valve  400  installed at the aortic valve  304 . In this embodiment frame  402  of valve  400  extends distally away from the heart beyond platform  408 . This allows frame  402  to engage the sinotubular junction  336  and the aorta  302  to secure the frame in place. Frame  402  also extends to the annulus  338  to secure frame  402 . In the embodiment shown in  FIGS. 9A-9B , a middle portion  416  of frame  402  has a large diameter in its expanded configuration in order to engage the sinuses  318  and assist in maintaining sinotubular definition (i.e., the relationship between the diameters of the sinuses, the sinotubular junction, and the ascending aorta). However, middle portion  416  may alternatively have a reduced diameter, as shown in  FIGS. 13A-13B . Further, valve  400  may be installed such that frame  402  holds aortic valve  304  in an open configuration (not shown but similar to venous valve embodiment of  FIGS. 8A-8B ) to effectively disable the aortic valve to prevent inefficiency of the aortic valve from disrupting natural blood flow. 
         [0045]    During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises sufficiently, filaments  403  of valve  400  are forced to extend towards the aorta, thus allowing blood to flow in the direction of arrow  412 . When ventricular systole ends, pressure in the left ventricle rapidly drops. Filaments  403  are flexible and light enough such that this drop in pressure causes filaments  403  to fall towards the left ventricle and getting caught against platform  408  to prevent retrograde blood flow  414 . 
         [0046]    As noted in the Background section above, a concern in aortic valve replacements is maintaining flow into the coronary ostia. As can be seen in  FIGS. 9A-9B  (and in  FIGS. 13A-13B  described below), the coil design of valve  400  will not risk blocking the coronary ostia  350 ,  352 . Accordingly, valve  400  (as well as the other one-way valve embodiments described herein) provides an advantage over existing valve replacement devices that require openings to match the coronary ostia, or other accommodations to ensure that the coronary ostia are not blocked. 
         [0047]      FIGS. 8A-8B  and  9 A- 9 B show filaments  403  as small thread-like strands. However, filaments  403  can be any shape, such as elliptical, triangular, and rectangular, as shown in  FIG. 10A . Filaments  403  can be coupled to frame  402  by a thread, an adhesive, or any other means known to those skilled in the art. In the embodiment shown in  FIG. 10B , a portion of each filament  403  is wrapped around the wire of frame  402  and a thread  418  attaches the filament  403  to itself. 
         [0048]      FIGS. 11A-11B  are schematic representations of one-way valve  600  in accordance with another embodiment hereof. Valve  600  includes a coil or frame  602  and a flap  603  coupled to the frame  602 . Frame  602  similar to frame  402  and is preferably formed from a shape memory material, such as a nickel-titanium alloy (Nitinol), such that frame  602  is self-expanding. It would be understood by those skilled in the art that frame  602  can be made of other materials used, for example, in stents, and may be balloon expandable. In the embodiment shown in  FIGS. 11A-11B , frame  602  is a wire formed into a tubular coil. Flap  603  may be made from non-thrombotic materials such as Polyethylene terephthalate (Dacron®) and expanded polytetrafluoroethylene (ePTFE). 
         [0049]    A portion of frame  602  includes a platform  608 . As shown in  FIG. 11A , platform  608  is formed by the nitinol wire extending in a circular pattern towards a longitudinal axis  610  of frame  602 . Flap  603  is coupled to frame  602  at platform  608  by a thread  618 . Thread  618  couples flap  603  to frame  602  generally near the center flap  603  to allow the periphery of flap  603  to move in response to forces generated where valve  600  is installed. In particular, when blood flows in the direction of arrow  112 , the periphery of flap  603  folds or extends in the direction of flow, as shown in  FIG. 11A . When there is a pressure drop such that a force is generated in the direction of arrow  114 , flap  603  rests against platform  608 , as shown in  FIG. 11B , to create a barrier to retrograde blood flood. As best seen in  FIG. 11B , a middle portion  616  of frame  602 , adjacent to flap  603  in the blood flow direction, has a reduced diameter. This reduced diameter allows flap  603  to fold without interference from frame  602 . Flap  603  is generally circular in shape, although the shape of flap  603  can be modified to fit the particular location in which it is to be installed. 
         [0050]      FIGS. 12A-12B  are schematic illustrations of valve  600  installed in a vein  100  at the location of a venous valve  104 .  FIGS. 12A-12B  show frame  602  in its expanded configuration. Frame  602  is installed in vein  100  such that frame  602  holds venous valve  104  in an open configuration.  FIG. 12A  shows flap  603  folded in the direction of blood flow shown by arrow  112 , permitting blood to flow back towards the heart.  FIG. 12B  shows flap  603  resting flat against platform  608  of frame  602  to prevent retrograde blood flow  114 . 
         [0051]      FIGS. 13A-13B  are schematic illustrations of valve  600  installed at the aortic valve  304 . In this embodiment frame  602  of valve  600  extends distally away from the heart beyond platform  608 . This allows frame  602  to engage the sinotubular junction  336  and the aorta  302  to secure frame  602  in place. Frame  602  also extends to the annulus  338  to secure frame  602 . In the embodiment shown in  FIGS. 13A-13B , middle portion  616  of frame  602  has reduced diameter in its expanded configuration in order to allow flap  603  to fold in the direction of blood flow. During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises sufficiently, flap  603  of valve  600  folds toward the aorta, thus allowing blood to flow in the direction of arrow  112 . When ventricular systole ends, pressure in the left ventricle rapidly drops. Flap  603  is flexible and light enough such that this drop in pressure causes flap  603  to unfold towards the left ventricle until it rests against platform  608  to prevent retrograde blood flow  114 . 
         [0052]      FIG. 14  is a schematic representation of a valve  700  in accordance with another embodiment hereof. Valve  700  is similar to valve  600  shown in  FIGS. 11-13  in that it includes a frame  702  and a flap  703  coupled to frame  702 . However, in the embodiment shown in  FIG. 14 , shape memory fibers or wires  720  are incorporated into flap  703 . The shape memory fibers  720  can be, for example, nitinol fibers. Shape memory fibers  720  are incorporated into flap  703  such that shape memory fibers have a natural orientation that would orient flap  703  flat or generally perpendicular to the direction of blood flow. In other words, the natural orientation of shape memory fibers  720  would tend to keep flap  703  closed. However, this natural orientation would be overcome by the pressure of blood flow (upwards in  FIG. 14 ) to open valve  700 . When there is insufficient blood flow pressure to overcome the natural orientation of flap  703 , flap  703  will close. This embodiment provides for a more definite closing of flap  703 , rather than relying on retrograde blood flow to close the valve. The embodiment of  FIG. 14  can be used in a vein or at the aortic valve, as shown in  FIGS. 12 and 13  with respect to valve  600 . The portions of valve  700  not particularly described are identical to those portions in  FIGS. 11-13 , or can be as described in other embodiments herein. 
         [0053]      FIGS. 15A-15B  are schematic representations of another embodiment of a one-way valve  800 . Valve  800  is similar to valve  600  shown in  FIGS. 11-13  in that it includes a frame  802  and a flap  803  coupled to frame  802 . However, in the embodiment shown in  FIGS. 15A-15B , a sealing ring  822  is coupled to the outer periphery of platform  808  of frame  802 . Sealing ring may be made out of, but not limited to, silicone. As can be seen in  FIG. 15A , when flap  803  is closed (i.e., resting against platform  808 ), sealing ring  822  forms an outer ring around flap  803 . Preferably, there is some overlap between flap  803  and sealing ring  822 . As can be seen in  FIG. 15B , when flap  803  opens, sealing ring  822  remains in place since it is coupled to platform  808 . Sealing ring  822  provides a more definite seal at the outer periphery of valve  800  where frame  802  meets the inner wall of a vein or the sinus, depending on where valve  800  is installed. The embodiment of  FIGS. 15A-15B  can be used in a vein or at the aortic valve, as shown in  FIGS. 12 and 13  with respect to valve  600 . The portions of valve  800  not particularly described are identical to those portions in  FIGS. 11-13 , or can be as described in other embodiments herein. For example, the shape memory fibers described with respect to valve  700  can be used in valve  800 . 
         [0054]      FIGS. 16A-16B  are schematic representations of another embodiment of a one-way valve  900 . Valve  900  is similar to valve  600  shown in  FIGS. 11-13  and valve  800  shown in  FIGS. 15A-15B  in that it includes a frame  902  and a flap  903  coupled to frame  902 . Further, valve  900  includes a sealing ring  922  similar to sealing ring  822  of  FIGS. 15A-15B , although a sealing ring is not required. In the embodiment of  FIGS. 16A-16B , flap  903  is coupled to platform  908  at the periphery of flap  903 . Flap  903  also includes slits or cuts  924  extending from a center of flap  903  to the outer peripheral portion of flap  903 . The slits  924  preferably do not extend all the way through the outer edge of flap  902 , such that flap  903  is a single piece with slits  924 , rather then several smaller pieces. In the embodiment shown in  FIGS. 16A-16B , flap  903  includes six slits  924  such that there are six portions of flap  903 . Flap  903  may be attached directly to the outer periphery of platform  908  by threading, adhesive, or other methods known to those skilled in the art. Alternatively, the outer periphery of flap  903  may be attached directly to sealing ring  922 . Due the structure of this embodiment, when pressure from blood flow is in the direction of arrow  112 , as shown in  FIG. 16A , flap  903  opens from the center and the six portions extend in the direction of the blood flow. When there is a drop in pressure, flap  903  closes to prevent retrograde blood flow in the direction of arrow  114 , as shown in  FIG. 16B . The embodiment of  FIGS. 16A-16B  can be used in a vein or at the aortic valve, as shown in  FIGS. 12 and 13  with respect to valve  600 . The portions of valve  900  not particularly described are identical to those portions in  FIGS. 11-13 , or can be as described in other embodiments herein. 
         [0055]      FIG. 17  is a schematic illustration of a delivery catheter  1000  for delivering a one-way valve of the present disclosure. Delivery catheter  1000  includes lumen  1012  for holding the one-way valve. In the embodiment shown in  FIG. 17 , valve  800  described above with respect to  FIGS. 15A-15B  is illustrated. It would be understood by those skilled in the art that any of the valves described herein could be delivered in delivery catheter  1000 . Delivery catheter  1000  also includes a guidewire lumen  1014  through which a guidewire  1016  can pass. Delivery catheter further includes a pusher  1010  disposed at a proximal end of valve  800 . As illustrated in  FIG. 17 , frame  802  of valve  800  is unwound or straightened to fit in lumen  1012 . This illustrates the compressed configuration of the frame for delivery to the target site. This straightened configuration permits the valve to fit into a smaller diameter delivery catheter than other replacement valves. For example, delivery catheter  1000  may be in the range of 0.075 to 0.130 inches in diameter, compared to existing technologies which are in the range of 0.235 to 0.315 inches in diameter. Due to its shape memory material, frame  802  will revert to its coiled, tubular configuration when released from catheter  1000 . 
         [0056]      FIGS. 18-20  illustrate schematically a method of delivering valve  800  to the location of an incompetent venous valve using delivery catheter  1000 . Initially luminal access to a desired peripheral vein  1002 , such as the greater or lesser saphenous, femoral, or popliteal veins, is obtained using standard percutaneous techniques. Guidewire  1016  is then maneuvered through the vasculature to rest across a target location within lumen  1004  of vein  1002  where valve  800  is to be inserted. Guidewire  1016  is then backloaded into guidewire lumen  1014  of catheter  1000 , and catheter  1000  is advanced over guidewire  1016  to the target location, as shown in  FIG. 18 . 
         [0057]    Once catheter  1000  is in position, guidewire  1016  can be removed. Pusher  1010 , shown in  FIG. 17  may either be advanced distally, or catheter  1000  may be withdrawn proximally as pusher  1010  remains in place, or a combination of the both, in order to achieve relative longitudinal movement between pusher  1010  and catheter  1000 . Due to this relative longitudinal movement, valve  800  begins exiting catheter  1000 , as shown in  FIG. 19 . As frame  802  of valve  800  exits catheter  1000 , frame  802  reverts to its coils configuration, as shown in  FIG. 19 . Continued relative longitudinal movement between catheter  1000  and pusher  1010  results in the valve  800  completely exiting catheter  1000  and frame  802  securing valve  800  against  1002 . One skilled in the art would recognize that valve  800  can be loaded into catheter  1000  with either end of frame  802  facing distally, depending on the access point, valve location, and blood flow direction of the vein being accessed. Further, one skilled in the art would recognize that other delivery catheters and methods may be used to deliver a valve to a desired location. For example, a tubular, non-coiled self expanding frame could be utilized for the valve, and conventional means to delivery a tubular, non-coiled, self-expanding stent could be utilized. 
         [0058]    During delivery, catheter  1000  and/or valve  800  need to be visualized in order to ensure proper placement. Visualization of valve  800  may be accomplished, for example, by making frame  802  using a Nitinol wire with a tantalum core, as discussed above. In another example, marker bands, made from tantalum, gold, platinum, or other similar materials, may be added to frame  802  at various locations, as would be known by those of ordinary skill in the art. For example, marker bands may be added to the proximal and distal ends of frame  802 . In another example, pusher  1010  may be made of a radiopaque material or may have marker bands  1026  added thereto, as shown in  FIG. 17 . Further, catheter  1000  may have marker bands along the length thereof, for example, marker bands  1020 ,  1022 , and  1024  shown in  FIG. 17 . When marker band  1026  of pusher  1010  is aligned with one of the marker bands of catheter  1000 , the user knows that a certain portion of the valve  800  has exited catheter  1000  and is deployed. For example, as shown in  FIG. 17  but not to scale, when marker band  1026  of pusher  1010  is aligned with marker band  1020  of catheter  1000 , valve flap  803  has been deployed. Similarly, when marker band  1026  of pusher  1010  is aligned with marker band  1022  of catheter  1000 , platform  808  has been deployed, and when marker band  1026  is aligned with marker band  1024 , all of frame  802  of valve  800  has exited catheter  1000  and deployed. Although three marker bands for catheter  1000  have been described in this embodiment, it would be understood that more or less marker bands may be used. Further, other methods of visualizing valve  800  and catheter  1000  would be apparent to those of ordinary skill in the art. 
         [0059]    The valves and delivery catheter described herein would also permit partial deployment of the valve in order to verify its function, and possible retraction and repositioning of the valve, if necessary. Accordingly, the distal portion  805  of frame  802 , flap  803 , and platform  808  can be deployed. The operator can then visualize valve function. Distal portion  805  would allow for temporary anchoring to verify valve function. If the valve needs to be repositioned or otherwise recovered, a hook or grasping mechanism (not shown) on the pusher could retraction the valve back into the delivery catheter. The proximal portion of the valve could also include a hook or other capturing mechanism such that the entire valve could be deployed and then recaptured either for repositioning, or if the device needed removal for an unforeseen reason. 
         [0060]    It would be understood by those skilled in the art that although  FIGS. 18-20  were described with respect to delivery of a replacement venous valve, delivery catheter  1000  of  FIG. 17 , and the method illustrated in  FIGS. 18-20  an also be utilized to deliver a valve to replace an aortic valve or pulmonary valve. 
         [0061]    While various embodiments hereof have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope hereof should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.