Abstract:
A device and method for improving flow through a native blood vessel valve, such as the aortic valve, are provided. The present invention allows a miniature valve to be implanted into affected leaflets percutaneously, obviating the need for coronary bypass surgery. The method includes the cutting of small holes, on the order of 4 mm, in the leaflets of a targeted valve, thereby allowing blood to flow through the newly formed holes. The holes are used as attachment sites for the miniature valves of the present invention.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This invention is related to the invention described in the provisional application serial No. 60/407,414 filed on Aug. 28, 2002 entitled, MINI-VALVE HEART VALVE REPLACEMENT, and claims priority therefrom. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Blood vessel valves include flexible tissue leaflets that passively alternate between open and closed positions as the forces of a blood stream act upon them. As blood flows in a first direction, the leaflets are urged apart from each other, and allow the blood to pass. Between pulses, as the blood attempts to flow in a reverse direction, the blood acts upon upstream surfaces of the individual leaflets, causing the leaflets to move inwardly. As the leaflets move inwardly, the edges of the individual leaflets (two, in the case of bicuspid valves, and three in the case of tricuspid valves) abut against each other, effectively blocking the blood flow in the reverse direction.  
           [0003]    Valves are also present within the heart. The heart contains four one-way valves that direct blood flow through the heart and into the arteries. Three of these valves, the aortic valve, the tricuspid valve, and the pulmonary valve, each have three leaflets. The fourth valve, the mitral valve, has two leaflets. By defining a direction in which blood can flow, these valves are responsible for the resulting pump effect a heart has on blood when the heart beats.  
           [0004]    A number of diseases result in a thickening, and subsequent immobility or reduced mobility, of valve leaflets. Valve immobility leads to a narrowing, or stenosis, of the passageway through the valve. The increased resistance to blood flow that a stenosed valve presents eventually leads to heart failure and death.  
           [0005]    Treating severe valve stenosis or regurgitation has heretofore involved complete removal of the existing native valve followed by the implantation of a prosthetic valve. Naturally, this is a heavily invasive procedure and inflicts great trauma on the body leading usually to great discomfort and considerable recovery time. It is also a sophisticated procedure that requires great expertise and talent to perform.  
           [0006]    Historically, such valve replacement surgery has been performed using traditional open-heart surgery where the chest is opened, the heart stopped, the patient placed on cardiopulmonary bypass, the native valve excised and the replacement valve attached. More recently, it has been proposed to perform valve replacement surgery percutaneously, that is, through a catheter, so as to avoid opening the chest.  
           [0007]    One such percutaneous valve replacement method is disclosed in U.S. Pat. No. 6,168,614 (the entire contents of which are hereby incorporated by reference) issued to Andersen et al. In this patent, the prosthetic valve is collapsed to a size that fits within a catheter. The catheter is then inserted into the patient&#39;s vasculature and moved so as to position the collapsed valve at the location of the native valve. A deployment mechanism is activated that expands the replacement valve against the walls of the body lumen. The expansion force pushes the leaflets of the existing native valve against the lumen wall thus essentially “excising” the native valve for all intents and purposes. The expanded structure, which includes a scaffold configured to have a valve shape with valve leaflet supports, is then released from the catheter and begins to take on the function of the native valve. As a result, a full valve replacement has been achieved but at a significantly reduced physical impact to the patient.  
           [0008]    One particular drawback with the percutaneous approach disclosed in the Andersen &#39;614 Patent is the difficulty in preventing leakage around the perimeter of the new valve after implantation. Since it appears that the tissue of the native valve remains within the lumen, there is a strong likelihood that the commissural junctions and fusion points of the valve tissue (as pushed against the lumen wall) will make sealing of the prosthetic valve around the interface between the lumen and the prosthetic valve difficult. Furthermore, in some patients, the deflection of the leaflets against the lumen walls could potentially obstruct the ostial openings of the lumen.  
           [0009]    Although both the traditional open heart valve replacement surgery and the newer percutaneous valve replacement surgery replace a native valve in entirely different ways and both have their drawbacks, the paradigm of these two approaches is identical: Render the native valve useless, either through excision (open heart) or immobilization (percutaneous), and then implant a completely new replacement prosthetic valve to take over. In other words, both approaches rely entirely on the premise that the native valve must be entirely replaced (physically or functionally) by an entirely new prosthetic valve.  
           [0010]    In contravention of the prior art, the present invention introduces an entirely different paradigm to valve replacement surgery, something neither taught nor contemplated by the open heart approach or the percutaneous approach (e.g., U.S. Pat. No. 6,168,614) and something that largely avoids the drawbacks associated with both. More specifically, the present invention is premised on leaving the native valve in place, not on its excision or immobilization, and then utilizing the native valve as a platform for actually treating the diseased valve. This is a wholly new approach to treating diseased valves.  
           [0011]    For example, in one embodiment of the invention, the physician diagnoses that the patient has a stenotic valve and then percutaneously mounts a plurality of small “leaflet valves” or “mini-valves” on one or more of the diseased native valve leaflets. In other words the native valve and its leaflets are used as a planar surface or a type of “bulkhead” on which new mini leaflet valves are mounted. The native valve remains in place but valve disfunction is remedied due to the presence of these new leaflet valves. As a result, the diseased valve is successfully treated without the complication associated with removing the native valve.  
           [0012]    This leads to a much simpler and safer approach as compared to the prior art. It avoids the invasive nature of the open heart approach and avoids the sealing and ostial blockage problems of the percutaneous approach.  
         BRIEF SUMMARY OF THE INVENTION  
         [0013]    The present invention relates to the treating of narrowed, stiff or calcified heart valves. The aforementioned problems with present treatment methods are addressed by treating the targeted valve leaflets individually, rather than replacing the entire valve using an open-heart or a percutaneous procedure. That is, in the present method, the rigid heart valve leaflet is treated by introducing small prosthetic valves into the leaflet itself.  
           [0014]    The present invention includes a method of treating the individual leaflets of a targeted heart valve that includes installing one or more small, one-way valves into the targeted leaflets. These smaller valves can be placed in the leaflet using catheter systems, obviating the need for opening the heart or great vessels, cardiopulmonary bypass, excision of the diseased valve, and a thoracotomy. Additionally, multiple small valve placements might reduce the long-term risks associated with a complete prosthetic valve, because failure of an individual valve will not necessarily lead to cardiac failure. The remaining small valves and remaining healthy native valves might be sufficient to sustain life.  
           [0015]    One aspect of the present invention provides a method of placing small valves through a target valve that involves puncturing the target valve and pushing the miniature valve through the target valve tissue. The valve is then anchored in place using a variety of mechanisms including tabs, riveting of the valve housing, spines, friction placement or the use of a fixation cuff.  
           [0016]    Another aspect of the present invention provides a variety of valve implant mechanisms constructed and arranged for placement in a target valve leaflet. The valve implant mechanisms include a valve housing that operably houses a valve mechanism such as a duckbill valve, a tilting check valve, a ball and cage valve, or a hinged leaflet valve or a valve using tissue leaflets. The valve implant may also include an anchoring mechanism such as tabs, spines, threads, shoulders, or a deformable housing.  
           [0017]    The present invention also provides a device useable to remove a section of the target valve, without damaging the surrounding valve tissue, and inserting a valve implant into the void left in the target valve. The device is contained within a catheter such that a valve implant insertion procedure can be accomplished percutaneously. Preferably, this delivery system is constructed and arranged to be placed through a 14 French catheter, traverse the aorta, land on a targeted leaflet such as one of the leaflets of the aortic valve, puncture the leaflet at a predetermined spot, cut a hole on the order of 4 mm in diameter, capture and remove any cut tissue, place a radially compressed one-way valve including a attachment cuff made of a shape memory alloy material (e.g., Nitinol) and a stainless steel sizing ring into the leaflet hole, securely attach the valve assembly to the leaflet, dilate the hole and the valve assembly to a precise final diameter, such as 8 mm, using a balloon, and be retracted leaving the valve assembly in place in the leaflet. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a perspective view of three valve implants of the present invention installed in the leaflets of a tricuspid valve;  
         [0019]    [0019]FIG. 2 is a side elevation of two valve implants of the present invention installed in a stenotic leaflet;  
         [0020]    [0020]FIGS. 3 a - f  are side elevations of various embodiments of the valve implant of the present invention;  
         [0021]    [0021]FIG. 4 a  is a detailed sectional view of a preferred embodiment of the valve implant of the present invention in a compressed or folded state;  
         [0022]    [0022]FIG. 4 b  is a detailed sectional view of the valve implant of FIG. 4 a  in an expanded state;  
         [0023]    [0023]FIGS. 4 c - f  are sectional views of alternative configurations of the preferred valve implant of the present invention;  
         [0024]    [0024]FIG. 5 a  is a sectional view of an embodiment of the delivery system of the present invention;  
         [0025]    [0025]FIG. 5 b  is a detailed sectional view of the distal end of the delivery system of FIG. 5 a;    
         [0026]    [0026]FIG. 6 is a sectional view of the leaflet capture catheter of the present invention;  
         [0027]    [0027]FIG. 7 a  is a sectional view of the delivery catheter of the present invention;  
         [0028]    [0028]FIG. 7 b  is a perspective view of an alternative cutter of the present invention;  
         [0029]    [0029]FIG. 8 is a sectional view of the sheath catheter of the present invention;  
         [0030]    [0030]FIG. 9 a  is a detailed sectional view of the handle of the delivery system of the present invention;  
         [0031]    [0031]FIG. 9 b  is a side elevation of the handle of FIG. 9 a;    
         [0032]    [0032]FIG. 10 a  is a side elevation of the handle of the present invention in a “Deliver” position;  
         [0033]    [0033]FIG. 10 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Deliver” position of FIG. 10 a;    
         [0034]    [0034]FIG. 11 a  is a side elevation of the handle of the present invention in an “Insert” position;  
         [0035]    [0035]FIG. 11 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Insert” position of FIG. 11 a;    
         [0036]    [0036]FIG. 12 a  is a side elevation of the handle of the present invention in a “Cut” position;  
         [0037]    [0037]FIG. 12 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Cut” position of FIG. 12 a;    
         [0038]    [0038]FIGS. 13 a - e  are an operational sequence of the capture device of FIG. 6 interacting with the cutting drum of FIG. 7 a  to remove and capture a section of tissue from a target valve leaflet;  
         [0039]    [0039]FIG. 14 a  is a side elevation of the handle of the present invention in a “Distal” position;  
         [0040]    [0040]FIG. 14 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Distal” position of FIG. 14 a;    
         [0041]    [0041]FIG. 15 a  is a side elevation of the handle of the present invention in a “Proximal” position;  
         [0042]    [0042]FIG. 15 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Proximal” position of FIG. 15 a;    
         [0043]    [0043]FIG. 16 a  is a side elevation of the handle of the present invention in an “Inflate” position;  
         [0044]    [0044]FIG. 16 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Inflate” position of FIG. 16 a  and a balloon of the delivery system is inflated;  
         [0045]    [0045]FIG. 17 a  is a side elevation of the handle of the present invention in an “Inflate” position during a deflating procedure;  
         [0046]    [0046]FIG. 17 b  is a sectional view of the distal end of the delivery system of the present invention when the handle is in the “Inflate” position of FIG. 17 a  and the balloon of the delivery system has been deflated;  
         [0047]    [0047]FIG. 18 is a sectional view of a valve implant of the present invention in a deployed configuration;  
         [0048]    [0048]FIGS. 19A and 19B are cross-sectional views of a valve implant of the present invention in a deployed configuration;  
         [0049]    [0049]FIG. 20 is a cross-sectional view of a portion of a catheter delivery system in accordance with a preferred embodiment of the present invention;  
         [0050]    [0050]FIG. 21 is a flow chart figure showing a tether retraction system for use in a catheter delivery system in accordance with the present invention;  
         [0051]    [0051]FIGS. 22A and 22B are top views of a hinged valve in accordance with another preferred embodiment of the present invention;  
         [0052]    [0052]FIGS. 23A, 23B and  23 C are cross-sectional views of a hinged valve in accordance with the present invention; and,  
         [0053]    [0053]FIGS. 24A and 24B are cross-sectional views of a hinged valve in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0054]    Referring now to the Figures, and first to FIG. 1, there is shown a native tricuspid valve  5  with a valve implant  10  of the present invention installed in each of the three leaflets  7  of the tricuspid valve  5 . The valve implants  10  are shown in an open position to demonstrate that blood is allowed to flow through the valve implants  10 , in one direction, even though the native tricuspid valve  5  remains closed. These valve implants  10  would similarly work with a native bicuspid valve, unicuspid valve or quadracuspid valve.  
         [0055]    [0055]FIG. 2 demonstrates the positioning of a valve implant  10  in a native leaflet  7 . The leaflet  7  is shown as having calcified tissue  9 , characteristic of a stenosed valve. Notably, the valve implants  10  have been inserted through the calcified tissue  7 . Also notable is that there may be more than one valve implant  10  inserted into a single leaflet  7  if additional flow capacity is desired. Alternatively, though not shown, the valve implant  10  may be installed between the leaflets  7 . This configuration is especially feasible in heavily stenosed valves that have relatively immovable leaflets. Such leaflets may be fully or partially fused together. The valve implants generally comprise an anchoring mechanism  12  and a valve mechanism  14 .  
         [0056]    FIGS.  3 - 5  illustrate several embodiments of the valve implants  10  of the present invention. In FIGS. 3 a - f,  a family of valve implants  10  is provided that are characterized by a rigid housing  16  with a self-tapping tip  18 . The valve implants  10  of FIGS. 3 a - f  include a variety of valve mechanisms  14  and anchoring mechanisms  12 .  
         [0057]    The valve implant  10  of FIG. 3 a,  as well as those of FIGS. 3 c  and  3   d,  has a valve mechanism  14  that comprises a single flap  20 , hinged on one side, that acts against the rigid housing  16  to prevent flow in a reverse direction. A benefit of this valve design is ease of construction. The valve implant  10  of FIG. 3 a  also uses the friction between the rigid housing  16  and the native heart leaflet  7  (FIG. 2) as an anchoring mechanism to hold the valve implant  10  in place. The pointed tip  18  allows the valve implant  10  to be urged through, or twisted through, the native heart leaflet without the need for cutting a hole in the leaflet prior to installing the valve implant  10 . Thus, in certain cases, there is sufficient gripping power between the housing  16  and the leaflet  7  to hold the housing  16  in place. This holding power may be increased by providing a textured surface (not shown) on the housing  16 , or selecting a housing material, such as a mesh or stiff fabric, that allows a controlled amount of ingrowth, sufficient to secure the valve implant  10 , but not so much as to cause a flow hindrance within the valve implant  10 .  
         [0058]    The valve implant  10  of FIG. 3 b  has a valve mechanism  14  that comprises a pair of members constructed and arranged to form a duckbill valve  22 . The duckbill valve  22  operates in a similar way to a tricuspid or bicuspid valve. When fluid flows through the valve in a desired direction, each of the members of the duckbill valve  22  move apart from each other. When the flow reverses, such as during diastole, the fluid forces the members of the duckbill valve  22  together, closing the valve  10 .  
         [0059]    Also included in the valve implant  10  of FIG. 3 b  is an anchoring mechanism  12 . The anchoring mechanism  12  generally comprises a plurality of radially extending posts  24 . These posts  24  act against an upstream side  26  (FIG. 2) of the leaflet  7 , thereby counteracting systolic pressure from the blood stream.  
         [0060]    The valve implant  10  of FIG. 3 c  includes a single flap  20  valve mechanism  14  and an anchoring mechanism  12  that includes a plurality of angled barbs  28 . The barbs  28  are located near the upstream side of the valve implant  10  and are angled back toward the downstream side. The angled barbs  28  may provide increased gripping power, especially if more than one row, such as shown in FIG. 3 c,  are provided. Because one or more of the rows of barbs  28  will be located within the leaflet  7  when the valve implant is in place, the barbs  28  provide resistance to movement in both directions, and may stimulate ingrowth.  
         [0061]    The valve implant  10  of FIG. 3 d  provides a combination of many of the features already discussed. The valve  10  has an anchoring mechanism  12  that includes both posts  24 , on the downstream side to prevent valve movement in the upstream direction, and angled barbs  28  on the upstream side of the valve  10 . The valve mechanism  14  demonstrates another valve design. The valve mechanism is an outside-hinged dual flap valve  30 . The individual flap members rotate about their outer edges when influenced by fluid flow.  
         [0062]    [0062]FIG. 3 e  shows a valve implant  10  with a valve mechanism  14  that uses an inside-hinged dual flap valve  32 , with individual flap members that rotate about their inner edges when influenced by fluid flow. The valve implant  10  combines upstream posts  24  with upstream-angled barbs  28  on the downstream side of the valve implant  10 .  
         [0063]    The valve implant  10  shown in FIG. 3 f  combines a single flap  20 , as a valve mechanism  14 , with an anchoring mechanism  12  that uses an external helical thread  34  to anchor the valve implant  10  to a valve leaflet  7 . The helical thread  34  provides resistance to movement in both the upstream and downstream directions. The helical thread  34  also provides a self-tapping action when the valve implant  10  is being screwed into place in a leaflet  7 .  
         [0064]    One skilled in the art will realize that any of the aforementioned anchoring mechanisms  12  and valve mechanisms  14  may be combined in a single valve implant  10 . For example, the valve implants  10  shown in FIG. 2 include upstream and downstream posts  24  as well as upstream and downstream angled barbs  28 .  
         [0065]    A preferred embodiment of the valve implant  10  of the present invention is shown in FIGS. 4 a  and  4   b.  The valve implant  10  is expandable from the compressed configuration shown in FIG. 4 a,  to the expanded configuration shown in FIG. 4 b.  The valve implant  10  is constructed and arranged to fit within a catheter when in the compressed configuration. Compression may be accomplished radially, helically, longitudinally, or a combination thereof. Preferably, the compression of the valve implant  10  is radial.  
         [0066]    Like the aforementioned embodiments of the valve implants  10 , the valve implant  10  of FIG. 4 generally includes an anchoring mechanism  12  and a valve mechanism  14 . The anchoring mechanism  12  generally comprises a cuff  36  and a sizing ring  38 . The cuff  36  is preferably constructed of Nitonol and has a middle portion  40  a set of radially expanding distal legs  42  and a set of radially expanding proximal legs  44 .  
         [0067]    In the compressed state, the legs  42  and  44  are somewhat aligned with the middle portion  40  to allow the cuff  36  to be compressed into a catheter, preferably a 14 French catheter. The cuff  36  is either expandable or self-expanding. Upon release from the catheter, the legs  42  and  44  fold outwardly until they radiate from the middle portion  40  at approximately right angles to the longitudinal axis of the cuff  36 . The legs  42  and  44  are designed to act against the upstream and downstream sides, respectively, of a valve leaflet, sandwiching the leaflet therebetween and anchoring the cuff  36  to the leaflet.  
         [0068]    The anchoring mechanism  12  of the valve implant  10  shown in FIGS. 4 a  and  4   b  also includes a sizing ring  38 . The sizing ring  38  is preferably a stainless steel stent that circumjacently surrounds the middle portion  40  of the cuff  36 . The sizing ring  38  is constructed and arranged to expand with the cuff  36  until a predetermined size is reached. Once the predetermined size is reached, the sizing ring  38  prevents further expansion by the cuff  36 . Over expansion of the cuff  36  could render the valve mechanism  14  inoperable, cause calcified tissue to break away from the stenosed valve and become released into the blood stream, tear the leaflet tissue, or weaken the cuff  36 .  
         [0069]    The valve mechanism  14  includes a sleeve  46  and one or more valve members  48 . The sleeve  46  may be rigid or flexible, but it is preferably flexible. More preferably, the sleeve  46  is constructed of any sufficiently flexible material capable of withstanding the environment to which it will be subjected, including but not limited to, any mammalian tissue, including human or pig tissue, vertebrate tissue, or a polymer or other synthetic material. The valve members  48  are shown as being duckbill valves but may be any of the aforementioned discussed valve designs.  
         [0070]    Most preferably, the valve mechanism  14  comprises an intact harvested valve from an animal, such as pig, and is taken from an appropriate location such that the expanded, original size is suitable for use in the leaflets of the stenotic valve being treated. The harvested valve is sutured or otherwise attached to the inside surface of the cuff  36 . In operation, the valve implant  10  is compressed such that it can be placed in a small catheter for percutaneous delivery. At the time of delivery, the valve implant  10  is attached to a stenotic leaflet and radially expanded to its functional diameter. Prior to, or during expansion, the distal and proximal legs  42  and  44  expand radially, allowing the cuff  36  to create a strong bulkhead-like fitting on both sides of the leaflet. After attachment is made to the leaflet, the cuff  36 , sizing ring  38 , and the valve mechanism  14  are radially expanded to the functional diameter of the valve implant  10 . During this expansion, the sizing ring  38  exhibits plastic deformation until it achieves the maximum diameter, at which point the sizing ring  38  resists further expansion.  
         [0071]    [0071]FIGS. 4 c - 4   f  depict alternative configurations for the preferred valve implant  10 . The valve implant  10  in FIG. 4 c  has a sleeve  46  attached to the anchoring mechanism  12  with two rows of sutures  166  and is configured so an upstream edge  168  of the sleeve  46  is roughly aligned with the distal legs  42  of the anchoring mechanism  12 . The valve implant  10  in FIG. 4 d  has a sleeve  46  attached to the anchoring mechanism  12  with one row of sutures  166  and is configured so the upstream edge  168  of the sleeve  46  is roughly aligned with the proximal legs  44  of the anchoring mechanism  12 . The valve implant  10  in FIG. 4 e  has a sleeve  46  attached to the anchoring mechanism  12  with two rows of sutures  166  and is configured so the downstream edge  170  of the sleeve  46  is roughly aligned with the proximal legs  44  of the anchoring mechanism  12 . The valve implant  10  in FIG. 4 f  has a sleeve  46  attached to the anchoring mechanism  12  with one row of sutures  166  and is configured so the downstream edge  170  of the sleeve  46  is roughly aligned with the distal legs  42  of the anchoring mechanism  12 . The sleeve  46  may comprise a scaffold to which valve members  48  are attached, or the entire valve mechanism  14  may be a harvested tissue valve such as an aortic valve.  
         [0072]    In one preferred embodiment, the valve implant  10  can be configured to include commissural support structure like a wireform stent as sometimes found in known standard sized prosthetic tissue valves. In such a configuration, the valve material will comprise a biologic tissue such as human pericardium or equine pericardium or small intestine submucousal tissue. In the present invention, the material must be thin enough to be compressed and perhaps folded so as to fit the valve implant  10  within the delivery system (described below). In a preferred embodiment, such tissue has a thickness of around 180 microns or less.  
         [0073]    In another alternative embodiment, the cuff mechanism could be a torroidal shaped sack (not shown), similar in shape to a deflated inner tube, attached to the exterior surface of the base of the valve implant  10  and connected to a UV curable liquid polymer reservoir contained within the delivery catheter. The sack material is composed of an elastic material that can be radially expanded by a balloon angioplasty catheter or by the injection of the liquid polymer. The liquid adhesive contained within the sack can be transformed to a solid polymer through UV light activated cross-linking  
         [0074]    This sack, essentially empty, can be manipulated by the delivery catheter to straddle both sides or surfaces around the hole cut in the leaflet for receiving the valve implant  10 . Once located, the sack can be enlarged by an underlying balloon catheter. Then, UV curable liquid polymer can be injected into the sack through the delivery catheter. Once filled with an adequate amount of a polymer and adjusted distally/proximally to form sufficient bulges on both sides of the valve leaflet, a UV light emission source, located within the delivery catheter near the bag is activated to wash the adhesive filled bag with UV curing light. Once hardened by the UV effect, the cuff maintains its enlarged size without balloon support.  
         [0075]    Referring to FIGS.  22 A- 24 B, yet another embodiment of a valve implant  10  of the present invention is shown, this embodiment being a hinged valve. In this embodiment, the valve implant  10  comprises a valve “poppet”  221  that is connected to a valve leaflet  7  by an attachment mechanism  220  that operates much like a hinge. The valve poppet  221  pivots between a sealed and an unsealed condition around the pivot point of the attachment mechanism  220  according to the flow of blood (FIGS. 24A and 24B).  
         [0076]    The poppet  221  or “mini-leaflet” can be comprised of any material sufficiently flexible to allow for the described movement yet sufficiently durable to withstand the environment. For example, the poppet  221  may made from materials such as biologic tissue, a polymer or a carbon based material. Moreover, the poppet  221  could be coated with tissue prom the patient, e.g., tissue from a patient&#39;s vein wall. The poppet material may include supporting internal structure and/or an outer ring to ensure the structural integrity of the poppet  221  during operation. The poppet can have a curved in order to better conform the poppet  221  to the contour of the native leaflet  7 .  
         [0077]    In this regard, after a hole is created in the leaflet  7  (discussed below), the poppet  221  is pushed or screwed into the leaflet. It may be retained there by barbs or screw threads or by hooks or other types of retaining mechanisms.  
         [0078]    The attachment mechanism  220  (FIGS.  22 A- 22 B and  24 A- 24 B), in a preferred embodiment, is a hinge. The hinge may fabricated from such materials as a polymer strip, a biologic tissue strip, a metal (e.g., stainless steel) strip or a pryolytic carbon material. Referring to FIGS. 24A and 24B, the hinged mechanism may be attached to the leaflet  7  tissue using a barbed spike  240 .  
         [0079]    In an optional embodiment of the invention shown in FIGS.  22 A- 24 B, the valve implant  10  may also include a support ring  222  that is disposed around the inside perimeter of the hole that is cut in the leaflet  7  to receive the valve implant  10 . The support ring  222  may serve to limit embolization and to enhance leaflet integrity (thereby avoiding prolapse). The support ring  222  could be deployed into the hole either with an expanding balloon or it could be mechanically deployed using a mechanical spreader.  
         [0080]    Referring to FIGS.  23 A- 24 B, the optional support ring  222  may include struts  224 ,  225  that serve to capture the edges of the leaflet  7  in the hole so as to support and retain the support ring  220  at the site.  
       Catheter Delivery System  
       [0081]    Referring now to FIGS. 5 a  and  5   b,  there is shown a preferred embodiment of a catheter delivery system  50  of the present invention. The catheter delivery system  50  generally comprises a leaflet capture catheter  52 , a delivery catheter  54 , a catheter sheath  56 , and a handle  58 . The catheter delivery system  50  is preferably constructed and arranged for use with a guidewire  60 .  
         [0082]    As best seen in FIG. 6, the leaflet capture catheter  52  includes a cutter die  62  connected to a hemostatic hub  64  with a cannula  66 . The cutter die  62  may be of unitary construction and includes a conical distal end  68  that increases in radius proximally until a flat  70  is reached. Proceeding proximally, the flat  70  ends abruptly to form a capture groove  72 . At the proximal end of the capture groove  72 , the cutter die  62  returns to approximately the same diameter as the flat  70 . The purpose of the cutter die  62  is to “grab” tissue that resiliently “pops” into the capture groove  72 . Once in the capture groove  72 , the tissue is held in place as a cutter  90  (explained below) cuts through the tissue.  
         [0083]    One skilled in the art will realize that alternatives could be used instead of a cutter die  62 . For example, the cutter die  62  could be replaced with a balloon, constructed and arranged to be inflated on the upstream side of the leaflet  7  (or both sides of the leaflet to capture the tissue) and sized to fit within the cutter  90 . A second balloon could also be arranged to be inflated on the downstream side of the leaflet, such that the leaflet is captured between the two balloons. The balloon concept, though arguably more complicated and expensive, may prove useful in situations where a cut needs to be made in tissue that has lost the resiliency needed to “pop” into the capture groove  72  of the cutter die  62 . Other devices, such as barbs and clamps, are also envisioned to act in this manner.  
         [0084]    The cannula  66  connects with the cutter die  62  and the hemostatic hub  64 . At the distal end of the cannula  66  is a needle tip  74 . The needle tip  74  is angled to form a sharp point usable to puncture tissue. The cannula  66  includes a lumen  76  extending the length thereof. This lumen  76  is used to accommodate a guidewire  60  (FIG. 5).  
         [0085]    The hemostatic hub  64  allows the leaflet capture catheter  52  to be removably attached to the handle  58 . The hemostatic hub  64  includes a body  78 , a threaded knob  80 , and an elastomeric seal  82 . The body  78  defines an interior cavity  84  that is shaped to receive and hold a cannula hub  86  that is attached to a proximal end of the cannula  66 . The interior cavity  84  is also shaped to receive the elastomeric seal  82 , which is compressed between the threaded knob  80  and the body  78 . The interior cavity  84  is partially internally threaded to receive the external threads of the threaded knob  80 . The threaded knob  80  defines a guidewire port  88  that aligns with the interior cavity  84  and the lumen  76  of the cannula  66  so that a continuous port is available for the guidewire  60  to extend the length of the leaflet capture catheter  52 . When a guidewire  60  is inserted through the guidewire port  88 , the threaded knob  80  and the elastomeric seal  82  act together as a hemostatic valve. When the threaded knob  80  is rotated to compress the elastomeric seal  82 , the elastomeric seal  82  swells inwardly, until it forms a blood-tight seal around the guidewire  60 . The cannula  66  and the hub  64  are constructed and arranged to carry the tensile force generated during a hole cutting procedure, discussed in detail below.  
         [0086]    The leaflet capture catheter  52  is slidingly and coaxially contained within the delivery catheter  54 . The delivery catheter  54  is best shown in FIG. 7 a,  and includes a cutter  90 , a balloon catheter  92 , and a delivery catheter hub  94 . The cutter  90  is constructed and arranged to act with the cutter die  62  (FIG. 6) to cut tissue. The cutter  90  includes a cutter drum  96  that is a sharpened cylindrical blade having a cutting tip  98 . The cutter tip  98 , as shown in FIG. 7 a,  lies in a plane that is substantially perpendicular to a longitudinal axis of the delivery catheter. However, an alternative embodiment of the cutter drum  96 , shown in FIG. 7 b,  may provide increased cutting power. The cutter drum  96  in FIG. 7 b  has a curved, non-planar cutting tip  98 . Preferably, the cutter drum  96  is sized to cut a hole having a diameter of approximately 4 mm through a leaflet. The cutter drum  96  has a cutter bulkhead  100  at its proximal end that is attached to the balloon catheter  92  with an adhesive  102 . Other suitable attachment means for attaching the cutter drum  96  to the balloon catheter  92  include threads, welds, unitary construction and the like. To cut tissue, the cutter die  62  is pulled within the cutter drum  90 . Thus, the balloon catheter  92 , and the adhesive  102  fixing the bulkhead  100  to the balloon catheter  92 , must be able to carry the compressive force that results from opposing the equal and opposite tensile force applied to the leaflet capture catheter  52 .  
         [0087]    The balloon catheter  92  generally includes an inner tube  104  extending distally and proximally from within an outer tube  106 . A balloon  108  is connected at a distal end to the outside of the inner tube  104  and at a proximal end to the outside of the outer tube  106 . The outside diameter of the inner tube  104  is smaller than the inside diameter of the outer tube  106 , such that a fluid passageway is formed therebetween for inflation of the balloon  108 . A flexible valve stop  110  is attached to the outer tube  106  just proximal of the proximal end of the balloon  108 . The valve stop  110  has a flexible sleeve  112  that extends distally over the proximal end of the balloon  108 . The function of the valve stop  110  is to prevent proximal movement of the valve implant  10  during delivery. The valve implant  10 , as will be seen below, will be placed over the balloon  108 , distal of the valve stop  110 . The flexible sleeve  112  allows the balloon to inflate while maintaining a desired positioning of the valve implant  10 . The inner tube  104  has an inner diameter large enough to accommodate the cannula  66  of the leaflet capture catheter  52 . A proximal end of the balloon catheter  92  is attached to the catheter hub  94 .  
         [0088]    The catheter hub  94  includes a catheter hub body  114  that defines an inner cavity  116  and a balloon inflation port  118 . The proximal end of the inner cavity  116  has internal threads to receive an externally threaded knob  120 . An elastomeric seal  122  resides between the threaded knob  120  and the catheter hub body  114 . The threaded knob  120  defines a capture catheter port  124  that aligns with the interior cavity  116  of the body  114  and the interior of the balloon catheter  92  so that the leaflet capture catheter  52  may pass therethrough.  
         [0089]    The balloon catheter  92  is attached to the catheter hub  94  in such a manner that fluid introduced into the balloon inflation port  118  will flow between the outer tube  106  and the inner tube  104  to inflate the balloon  108 . The outer tube  106  is attached at its proximal end to the distal end of the interior cavity  116  of the catheter hub body  114 . Preferably, an adhesive  126  is used to connect the outer tube  106  to the interior cavity  116  of the catheter hub body  114  at a position distal of the balloon inflation port  118 . The inner tube  104  extends proximally from the proximal end of the outer tube  108 . The proximal end of the inner tube  104  is also attached to the interior cavity  116  of the catheter hub body  114 . However, this connection is made at a position proximal of the balloon inflation port  118 , preferably with an adhesive  128 . Thus, fluid entering the balloon inflation port  118  is blocked from flowing in a proximal direction by the proximal adhesive  128 . It is also blocked from traveling in a distal direction on the outside of outer tube  106  by the distal adhesive  126 . Instead, the fluid is forced to flow between the inner tube  104  and the outer tube  106  in a distal direction toward the interior of the balloon  108 .  
         [0090]    The leaflet capture catheter  52  and the delivery catheter  54  are slideably contained within the sheath catheter  56 . Referring now to FIG. 8, it can be seen that the sheath catheter  56  includes a large diameter sheath  130  attached to a distal end of sheath tubing  132 , which is attached at a proximal end to a sheath hub  134 . The sheath hub  134  secures the sheath catheter  56  to the handle  58 . The sheath hub  134  includes a tab  154 , the function of which will be explained below. The sheath  130 , sheath tubing  132 , and the sheath hub  134 , all define a delivery catheter port  136  that extends throughout the length of the sheath catheter  56 . The large diameter sheath  130 , is preferably a 14 French catheter, and sized to accommodate the cutter drum  96 .  
         [0091]    Referring now to FIGS. 9A and 9B, there is shown a preferred embodiment of the handle  58  of the present invention. The handle  58  includes a handle body  138  that defines at a bottom portion a figure grip  140 . An actuator  142  is pivotally attached to the handle body  138  with a pivot pin  164 . At the top of the actuator  142 , is a leaflet capture catheter bracket  144 . The leaflet capture catheter bracket  144  is constructed and arranged to hold the leaflet capture hemostatic hub  64 . At a top portion of the body  138  there is defined a slotted chamber  146 . The slotted chamber  146  is constructed and arranged to hold the delivery catheter hub  94  as well as the sheath hub  134 . The slotted chamber  146  includes external threads  148  around which the sheath retraction nut  150  rides. At the top of the slotted chamber  146  there is defined a slot  152  through which the balloon inflation port  118  of the delivery catheter hub  94  and a tab  154  of the sheath hub  134  extend. Below the slotted chamber  146 , a sheath retraction indicator  156  extends distally from the handle body  138 . Preferably, the handle  58  includes a safety button  158  that prevents a physician from unintentionally depressing the actuator  142 .  
         [0092]    The handle  58  is thus constructed and arranged to slide the leaflet capture catheter  52  in a proximal direction relative to the sheath catheter  56  and the delivery catheter  54  when the actuator  142  is squeezed toward the finger grip  140 , thereby pulling the hemostatic hub  64  in a proximal direction. The handle  58  is also constructed and arranged to slide the sheath catheter  56  proximally over the leaflet capture catheter  52  and the delivery catheter  54  when the sheath retraction nut  150  is rotated proximally. The operation of the handle  58  and the rest of the delivery system  50  are explained in more detail below.  
         [0093]    Referring to FIGS. 19A, 19B and  20 , in one embodiment of the present invention, the catheter delivery system  50  includes a tether  190  looped around the proximal legs  44  of the valve implant  10 . The tether extends from the proximal legs  44  all the way through the catheter until both ends of the tether  190  are joined at a connector  192  that resides outside the catheter delivery system  50  near the handle. The tether  190  allows the user to retract the valve implant  10  from the valve placement site after it has been deployed from the catheter if it is determined that the deployment was improper or in the event a complication arises with after deployment.  
         [0094]    For example, if after deployment, it is determined that placement of the valve implant  10  is incorrect, the physician can pull on the tether and retract the valve implant  10  as shown in FIG. 19B. If, on the other hand, it is determined that placement of the valve implant  10  has been successful, then the physician simply cuts the tether and pulls the free end out of from the proximal legs  44  and out of the delivery device as shown in FIG. 19A.  
       Operation  
       [0095]    Referring now to FIGS.  10 - 19 , the operation of the present invention is explained. Each of the following figures will include two drawings, a drawing that shows the position of the handle  58 , and a drawing of the corresponding catheter configuration.  
         [0096]    Referring now to FIG. 10, the first step a physician takes in using the delivery device  50  to place a valve implant  10  in a leaflet of a native valve is to use a guidewire  60  to locate the site of the native valve. The guidewire  60  is thus threaded through the necessary blood vessels to the site of the native valve. For example, if it were desired to place the valve implant  10  in, or between, the leaflets of the aortic valve, the guidewire  60  would be placed percutaneously in the femoral artery, or other suitable arterial access, advanced up the aorta, around the arch, and placed above the target leaflet of the aortic valve. Once the guidewire  60  is in place, the catheter delivery system  50  is advanced along the guidewire  60 .  
         [0097]    In FIG. 10 a,  it can be seen that the target leaflet  7  has been located with the guidewire  60  and the catheter delivery system  50  has been advanced along the guidewire  60  the target leaflet  7 . Positioning the catheter delivery system  50  on the target leaflet  7  may be aided using imaging methods such as fluoroscopy and/or ultrasound. FIG. 10 a  shows that when this step is performed, the sheath retraction nut  150  is in the “Deliver” position as shown on the sheath retraction indicator  156 . In the “Deliver” position, the sheath  130  covers the capture groove  72  of the cutter die  62 . The cutter  90  remains retracted proximal of the capture groove  72 . Also, the conical distal end  68  of the cutter die  62  extends from the distal end of the sheath  130 .  
         [0098]    In this regard, it is helpful to note that the target leaflet may actually include two leaflets if the leaflets are calcified together. For example, with reference to FIG. 1, if two leaflets have become calcified together along their edges or lines of coaptation, the present invention contemplates cutting a hole in a manner that traverses the leaflet edges and thereafter inserting a valve (as explained below) across both leaflet edges.  
         [0099]    Once satisfied that the target site has been reached with the catheter delivery system  50 , the next step is to traverse the tissue of the target valve leaflet  7 . However, before the cutter die  62  is advanced through the leaflet tissue  7 , the sheath catheter  56  must be retracted until the “Insert/Cut” position has been achieved. This is accomplished by rotating the threaded sheath retraction nut  150  until the nut  150  is aligned with the “Insert/Cut” marking on the sheath retraction indicator  156 . Rotating the sheath retraction nut  150  causes the nut  150  to act against the tab  154  of the sheath hub  134 .  
         [0100]    Referring now to FIGS. 11 a  and  11   b,  it can been seen that the target valve leaflet  7  has been punctured by either the guidewire  60 , in the event that a sufficiently sharp guidewire is being used, or more preferably, the needle tip  74  of the leaflet capture catheter  52 . When the needle tip  74  of the leaflet capture catheter  52  is used to puncture the leaflet, the guidewire  60  is first retracted so that it does not extend through the needle tip  74 .  
         [0101]    In one embodiment, the needle may be configured to have a hollow sharp shaft followed by a conical shank (not shown). This will allow the needle to create an initial penetration of the tissue followed by a more traditional puncturing action from the conical shank A needle configured in this manner will also assist in positioning the delivery device over each leaflet.  
         [0102]    The cutter die  62  is advanced through the leaflet  7  until the leaflet  7  snaps into the capture groove  72 . The conical distal end  68 , as it is being advanced through the leaflet  7 , will provide an increasing resistance that is tactily perceptible to the physician. Once the leaflet  7  encounters the flat portion  70 , the physician will detect a decreased resistance and can expect a snap when the resilient tissue snaps into the capture groove  72 . The guidewire  60  is then re-advanced into the ventricle (assuming the aortic valve is the target valve).  
         [0103]    In this regard, it is notable that in one embodiment of the invention, the guidewire could be fabricated to include a transducer at its distal end (not shown). The guidewire could then be used to measure ventricular pressure (e.g., left ventricular pressure when treating the aortic valve) and thus provide the physician greater ability to monitor the patient during the procedure.  
         [0104]    Once the physician is convinced that the leaflet  7  has entered the capture groove  72 , the cutting step may commence. Referring now to FIGS. 12 a  and  12   b,  the cutting step is demonstrated. Cutting is performed by depressing safety button  158  and squeezing the actuator  142 . After the safety button  158  and the actuator  142  are squeezed, the spring loaded safety button on  158  will travel from a first hole  160  in the actuator  142  to a second hole  162 . When the safety button  158  reaches the second hole  162 , it will snap into the second hole  162 , thereby locking the actuator  142  in place. This ensures that the cutter die is retracted into the cutter  90 , but that excess pressure is not placed on either the cutter die  62  or the cutter  90 . When the actuator  142  is squeezed, cutting is effected because the actuator  142  rotates, relative to the handle body  138 , around the pivot pin  164 . This action causes the leaflet capture catheter bracket  144  to move in a proximal direction thereby pulling the hemostatic hub  64  with it. Pulling the hub  64  causes the cannula  66  and the cutter die  62  attached thereto, to be pulled in a proximal direction relative to the delivery catheter  64 . The cutter die  62  enters the cutter  90 , thereby cutting the tissue. The clearance between the cutter die  62  and the cutter drum  96  is sufficiently minimal to prevent the occurrence of hanging “chads” in the cut. Additionally, the sharpened cutting tip  98  of the cutter  90  may be cut at an angle, or even include a point, such that the entire cut does not have to be initiated around the entire circumference of the cutter drum  96  simultaneously.  
         [0105]    A more detailed view of the cutting action of the cutter die  62  and the cutter  90  is shown in FIGS. 13 a - 13   e.  In FIG. 13 a,  the needle tip  74  of the cannula  66  has just reached the leaflet  7 . The sheath  130  has been retracted to the “Insert/Cut” position as indicated by the exposed capture groove  72  of the cutter die  62 . In FIG. 13 b,  the cutter die  62  is being advanced through the target leaflet  7  such that the target leaflet  7  has reached the conical distal end  68  of the cutter die  62 . In FIG. 13 c,  the conical distal end  68  and the flat portion  70  of the cutter die  62  have passed completely through the target leaflet  7 , and the target leaflet  7  has snapped into the capture groove  72 . Additionally, the guidewire  60  has been re-advanced through the leaflet capture catheter  52  so that it extends beyond the needle tip  74 . The guidewire  60  will be used to retain the position of the hole cut through the leaflet  7  after the cutter die  62  is retracted. In FIG. 13 d,  the physician has begun to cut by squeezing the actuator  142  (FIG. 12 a ), as evidenced by the advancement of the cutter  90 . The cutting tip  98  of the cutter  90  has been advanced mid-way through the target leaflet  7 . This movement is relative to the position of the cutter die  62 . More accurately, the cutter die  62  is being retracted into the cutter  90 , bringing with it the tissue of the leaflet  7 . The movement of the cutter die  62  is evidenced by arrow  172 .  
         [0106]    In FIG. 13 e,  the cut is complete as the actuator  142  has been squeezed enough so that the safety button  158  has found the second hole  162  (FIG. 12 a ), as evidenced by the position of the cutter die  62 . The cutter die  62  is retracted enough such that the capture groove  72  is completely housed within the cutter drum  96 . Notably, the cut tissue of the leaflet  7  remains trapped between the capture groove  72  and the cutter drum  96 . The trapping of this tissue prevents the tissue from traveling downstream through the blood vessel and causing damage.  
         [0107]    Referring now to FIGS. 14 a  and  14   b,  once the hole in the tissue  7  is cut, the step of placing the valve implant  10  begins. First, the entire delivery system  50  is moved distally deeper into the patient such that the distal legs  42  pass through the newly formed hole in the tissue  7 . It is important that at least the distal legs  42  are located on the upstream (ventricle) side of the tissue  7  prior to deploying the valve implant  10 . Once the physician is confident that the distal legs  42  extend beyond the valve leaflet tissue  7 , the sheath  130  may be retracted to release the distal legs  42 . This is accomplished by rotating the sheath retraction nut  150  until the sheath retraction nut  150  aligns with the “Distal” marking on the sheath retraction indicator  156 . Doing so causes the sheath retraction nut  150  to act against the tab  154  thereby withdrawing the sheath  130  until just the distal legs  42  are exposed. The distal legs  42  are preloaded such that they spring outwardly, as shown in FIG. 14 b,  when uncovered by the catheter sheath  130 . The distal legs  42  are long enough to extend beyond the radius of the sheath  130 , such that they may act against the valve leaflet tissue  7 . Once the sheath retraction nut  150  has been rotated to the “Distal” position on the indicator  156 , the physician may pull the catheter delivery system  50  in a proximal direction until he or she feels the distal legs  42  catch or act against the valve leaflet tissue  7 . Notably, the actuator  142  remains locked in the position it was placed in during the cutting procedure. Leaving the actuator  142  in this position ensures that the valve leaflet tissue trapped between the cutter die  62  and the cutter drum  96  is not released.  
         [0108]    The next step is illustrated in FIGS. 15 a  and  15   b.  The physician maintains the contact between the distal legs  42  and the valve leaflet tissue  7 . While maintaining this contact, the sheath retraction nut  150  is rotated to the “Proximal” position as indicated on the marker of the sheath retraction indicator  156 . Rotating the sheath retraction nut  150  again acts against the tab  154  causing the sheath  130  to retract further. When the proximal position has been achieved, the sheath will be retracted enough to release the proximal legs  44 . Like the distal legs  42 , the proximal legs  44  will spring outwardly when released by the sheath  130 . The proximal legs  44  act against the opposite side (aorta side) of the valve leaflet tissue  7  sandwiching the valve leaflet tissue  7  between the distal legs  42  and the proximal legs  44 . The valve implant  10  is now attached to the patient.  
         [0109]    The next step is to inflate the balloon  108  thereby expanding the valve implant  10 . This step is best shown in FIGS. 16 a  and  16   b.  The physician further rotates the sheath retraction nut  150  to the “Inflate” position on the indicator  156 . The sheath retraction nut  150  again acts against the tab  154  thereby retracting the sheath  130  to a point where the valve stop  110  is at least partially exposed and the flexible sleeve  112  of the valve stop  110  is completely exposed.  
         [0110]    Once the sheath  130  has been retracted to the “Inflate” position on the indicator  156 , the balloon  108  may be inflated. This is accomplished by injecting fluid into the balloon inflation port  118 . Fluid is injected until the sizing ring  38  has achieved its maximum diameter. The physician will feel resistance against further inflation by the sizing ring  38 . Additionally, the sizing ring  38  or other parts of the anchoring mechanism  12  may be constructed of a radiopaque material such that monitoring can be accomplished using X-ray equipment. The use of the sizing ring  38  is not required for the practice of the invention. It is, however, preferred in the preferred embodiments of the invention.  
         [0111]    Once the inflation of the balloon  108  is complete, the next step involves deflating the balloon  108 . This is illustrated in FIGS. 17 a  and  17   b.  Deflating the balloon involves simply withdrawing fluid through the balloon inflation port  118 . As is shown in FIG. 17 b,  when the balloon  108  is deflated, the valve implant  10  retains its inflated proportions. These inflated proportions allow easy retraction of the catheter delivery system through the valve implant  10 . As is best seen in FIG. 18, once the delivery system  50  has been retracted, the valve implant  10  remains attached to the valve leaflet tissue  7 .  
         [0112]    As discussed above with reference to FIGS. 19A, 19B and  20 , one embodiment of the catheter delivery device  50  and the valve implant  10  includes the use of a tether  190  to allow the physician to retract the valve implant  10  in the event of improper deployment. With reference to FIG. 21, the operation of the tether  190  under both proper deployment and improper deployment is disclosed.  
         [0113]    On the left side of FIG. 21, it is seen that the valve implant  10  has been properly deployed in the valve leaflet. As a result, the physician cuts the tether  190  and pulls the tether away from the catheter handle from the proximal legs  44  of the cuff.  
         [0114]    On the right side of FIG. 22, it is seen that the valve implant  10  has been improperly deployed insofar as the legs of the cuff have not adequately grasped the edge of the hole in the leaflet. As a result, the physician may retract the valve implant  10  by pulling on the tether  190  and thus removing the valve implant  10  from its improperly deployed location