Abstract:
A support, and a method for attaching said support, for providing additional strength to existing regurgitant or prolapsed valve leaflets. The support restores an otherwise non-functioning, or poorly functioning, native valve to a functioning condition, obviating the need for a complete valve removal or replacement. The support may also be applied to a functioning valve leaflet as a prophylactic measure against future failure. The delivery method includes a delivery mechanism for attaching the support to the native valve leaflet.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/393,794, filed Jul. 3, 2002, the contents of which are incorporated by reference. 
     
    
     
       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]    If the individual leaflets suffer degradation in structural integrity, such as degeneration, a prolapse condition may result. FIGS. 1 through 3 demonstrate the mechanics of a regurgitant valve with leaflet prolapse. FIGS. 1 a  and  1   b  show a healthy tricuspid valve  1  in the open position. The direction of blood flow is indicated by arrow  2 . The valve  1  includes three leaflets  3  growing into the lumen of a blood vessel  4 . It can be seen that when the blood is flowing in the direction shown by arrow  2  of FIG. 1 a , the flexible valve leaflets  3  naturally fold themselves against the interior walls of the blood vessel  4 , thereby minimizing their impact on blood flow in that direction.  
           [0004]    As depicted in FIG. 2 a , when blood attempts to flow in the reverse direction, between cardiac pulses, these valve leaflets  3  move inward, toward each other. As best shown in FIG. 2 b , when the leaflets  3  abut, they form a seal  5 , effectively preventing fluid flow in the direction of arrows  2  from FIG. 2 a . The seal  5  can only be formed if all three valve leaflets  3  are structurally sound.  
           [0005]    When a valve, such as valve  1  of FIG. 3, has a prolapsed leaflet  3   a , the seal  5  cannot be effectively formed. Leaflet  3   a  lacks the structural integrity of the healthy leaflets  3 . When the flow is reversed, as indicated by arrow  2 , the healthy leaflets  3  balloon inwardly. However, the prolapsed leaflet  3   a  falls away from the seal  5 , leaving a significant gap  6  in the seal  5 . Blood passes through the gap  6 , resulting in a loss of systolic pressure, as well as a reduction in the pumping efficacy of the heart.  
           [0006]    Current methods of repairing prolapsed valves involve replacing the valve entirely with a prosthetic valve. The structurally sound leaflets are not preserved. It would be advantageous to provide a method of repairing a prolapsed valve, leaving as much of the native valve as possible intact, thereby minimizing the risk of rejection, and preserving the healthy leaflets. Percutaneous treatment would obviate the risks associated with open heart surgery.  
         SUMMARY OF THE INVENTION  
         [0007]    In one aspect of the present invention, there is a method for repairing a prolapsed valve that involves reinforcing the prolapsed leaflet or leaflets to reestablish the structural integrity thereof. The method involves attaching a support to one or both sides of the valve. The support is constructed and arranged to allow the leaflet to open when blood is flowing through the valve in the natural direction. When the flow is reversed during a diastole, the support resists, preventing the leaflet from prolapsing.  
           [0008]    In another aspect of the present invention, a support is provided that is attachable to the downstream side of a prolapsed valve leaflet. The support includes an attachment mechanism, preferably barbs, staples, or similar suitable tissue-grabbing means. The support may be bifurcated with one or more hinge, allowing one side of the support to pivot relative to the second side. The hinge is constructed and arranged with a stop, so that the hinge prevents pivoting past a sealing point. Preferably, the hinge is constructed to avoid pinching the leaflet tissue with the stop is reached.  
           [0009]    Another aspect of the present invention provides a support that is attachable to the upstream side of a prolapsed valve leaflet. The construction of the upstream support is very similar to that of the downstream support. The upstream support also includes an attachment mechanism, preferably barbs, staples, or similar suitable tissue-grabbing means. Again, the support may be bifurcated with one or more hinge, allowing one side of the support to pivot relative to the other side. The hinge is also constructed and arranged with a stop, so that the hinge prevents pivoting past a sealing point. Placing the support on the upstream side of the valve may be advantageous because the stress encountered during diastole, when the support is preventing the leaflet from prolapsing due to the pressure of the blood, acts in conjunction with the attachment mechanism, rather than against it. Thus, the support is less likely to become separated from the leaflet.  
           [0010]    Yet another aspect of the present invention provides a support that includes both upstream and downstream members. These members are similar in construction to the upstream and downstream members. However, the attachment mechanism used in this aspect takes advantage of the additional structure provided by the opposing support. The opposing supports lock together, through the prolapsed leaflet, sandwiching the leaflet therebetween. Preferably, one member includes male connectors, while the other member includes corresponding female connectors. Alternatively, each side includes one or more male and one or more female connectors, and the other member includes corresponding mating connectors. Whereas the downstream member may provide a single hinge, the upstream member may provide a double or triple hinge, constructed and arranged to allow the upstream member to move with the downstream member, without changing the relative position between the two members. Providing such an arrangement avoids the occurrence of locked hinges and/or tearing the leaflet tissue between the two members. Alternatively, one or both supports may be hingeless.  
           [0011]    Still another aspect of the present invention provides a support with a more complex, multi-member structure, flexible in one direction but rigid in another direction. This structure obviates the necessity of hinges. The support members form a frame with either an open or covered interior.  
           [0012]    A further aspect of the present invention includes a woven, pressed, laminar or similar substrate-like hingeless support. This support operates on the principle that strength is achieved in an otherwise flimsy substrate when the substrate is curved. This principle is easily demonstrated by holding a piece of paper while imparting a curve onto the paper with one&#39;s fingers. The paper can be made to easily support itself or even to hold other objects on the concave side, without supporting opposite sides of the paper. However, placing pressure on the convex side of the curved paper causes the paper to quickly bend. Steel tape measures operate on this principle. The tape measures are curved and can be bent easily in one direction but are relatively rigid in the opposite direction.  
           [0013]    Yet another aspect of the present invention includes a method of attaching a support to a prolapsed valve leaflet. The method involves passing a wire from the aorta through the prolapsed valve. A catheter is then guided over the wire that contains the support mechanism. Preferably, the support mechanism includes a biasing means that allows the support to be pre-loaded in the catheter such that, when released from the catheter sheath, the support mechanism attaches itself to the prolapsed valve leaflet. Alternatively, a positioning means is provided so the support members do not require pre-loading in the catheter unit. The positioning means would allow manual manipulation of the support members during placement. The support is preferably removably attached to the leaflet, thereby allowing removal and reattachment if necessary. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 a  is a sectional view of a healthy native tricuspid valve in an open position;  
         [0015]    [0015]FIG. 1 b  is a sectional view of the valve of FIG. 1 a  taken along lines  1   b - 1   b;    
         [0016]    [0016]FIG. 2 a  is a sectional view of a healthy tricuspid valve in a closed position;  
         [0017]    [0017]FIG. 2 b  is a sectional view of the valve of FIG. 2 a  taken along lines  2   b - 2   b;    
         [0018]    [0018]FIG. 3 a  is a sectional view of a native prolapsed valve;  
         [0019]    [0019]FIG. 3 b  is a sectional view of the valve of FIG. 3 a  taken along lines  3   b - 3   b;    
         [0020]    [0020]FIG. 4 is a perspective view of an unhinged downstream embodiment of the present invention;  
         [0021]    [0021]FIG. 5 is a perspective view of a hinged downstream embodiment of the present invention;  
         [0022]    [0022]FIG. 6 is an end view of the embodiment of FIG. 5 attached to a valve leaflet;  
         [0023]    [0023]FIG. 7 is a perspective view of a downstream hinge of the present invention;  
         [0024]    [0024]FIG. 8 is a perspective view of an unhinged upstream embodiment of the present invention;  
         [0025]    [0025]FIG. 9 is a perspective view of a hinged upstream embodiment of the present invention;  
         [0026]    [0026]FIG. 10 is a side elevation of a hinged embodiment of the present invention having members on both the upstream and downstream sides of a prolapsed leaflet;  
         [0027]    [0027]FIG. 11 is a perspective view of a substrate embodiment of the present invention in a closed position;  
         [0028]    [0028]FIG. 12 is a perspective view of a substrate embodiment of the present invention in an open position;  
         [0029]    [0029]FIG. 13 is a perspective view of a multi-member structure embodiment of the present invention;  
         [0030]    [0030]FIGS. 14 a - d  are a series of drawings depicting a preferred method of attaching a support to a prolapsed leaflet;  
         [0031]    [0031]FIG. 15 is an elevation of a preferred delivery device of the present invention; and,  
         [0032]    [0032]FIG. 16 is a perspective view of a preferred delivery device of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    Referring now to the Figures, and first to FIG. 4, there is shown unhinged embodiment of a support  10  of the present invention. Support  10  includes a support member  12 , which is curved to approximately match the curve of a healthy valve leaflet in a closed position. The curve defines a convex side  14  and a concave side  16  of the support member  12 . A plurality of barbs  18  extend from the support member  12 , and are constructed and arranged to penetrate and catch the tissue of a prolapsed leaflet, securing the support member  12  thereto. That the barbs  18  extend from the convex side indicates that the support  10  of FIG. 4 is constructed and arranged for attachment to the downstream side of a prolapsed leaflet.  
         [0034]    The support  10  is a biocompatible material. Acceptable biocompatible metals that could be used to construct the support  10  include, but are not limited to, Nitonol, stainless steel, titanium, and other appropriate metals. Acceptable non-metal biocompatible materials include, but are not limited to, PTFE, pyrolytic carbon, or any appropriate polymer.  
         [0035]    [0035]FIG. 5 shows a hinged embodiment of a support  10 . The support  10  is bifurcated into a first part  20  and a second part  22 . The first part  20  and the second part  22  are connected with a hinge  24 , which allows the second part  22  to rotate relative to the first part  20 . Rather than the barbs  18  shown in FIG. 4, the support  10  of FIG. 5 uses a plurality of staples  26  as an attachment mechanism. FIG. 6 shows the staples  26  attaching the support  10  to a valve leaflet  3 . The staples  26  are shown with a hinged embodiment  10  but there is no association between the staples  26  and the hinge  24 . The barbs  18  of FIG. 4 could be used with a hinged embodiment of support  10 , and vice versa.  
         [0036]    The hinge  24  is preferably designed to prevent pinching the valve leaflet  3  during operation. FIG. 7 provides a detailed view of the hinge  24 . It can be seen that the hinge  24  includes a first part component  28 , integral with the first part  20  and a second part component  30  integral with the second part  22 . The components  28  and  30  are constructed and arranged to form an interfering stop  32  on a side opposite of the valve leaflet  3 .  
         [0037]    [0037]FIG. 8 shows a support  10  constructed and arranged for attachment to an upstream side of a valve leaflet. Again, the support member  12  has a convex side  14  and a concave side  16 . However, the attachment mechanism, shown as barbs  18 , protrude from the concave side  16 , placing the support member  12  on the upstream, convex side of the leaflet.  
         [0038]    [0038]FIG. 9 shows a hinged support  10  constructed and arranged for attachment to an upstream side of a valve leaflet. Again, the attachment mechanism, a plurality of barbs  18 , protrudes from the concave side  16 . The hinge  24  of the upstream, hinged embodiment includes a stop on the upstream side, so as to prevent pinching the leaflet tissue.  
         [0039]    [0039]FIG. 10 shows a support  10  that provides additional support and is less reliant on the structural integrity of the leaflet tissue for attachment purposes than the aforementioned embodiments. The support  10  includes an upstream member  32  and a downstream member  34 . The upstream member  32  is attached to the downstream member  34  through the valve leaflet  3  with an attachment mechanism  36 . The attachment mechanism  36  shown includes a plurality of male posts  38  that extend through and engage corresponding apertures  40  through the downstream member  34 . A variety of alternatives may be effectively used as attachment mechanism  36 . For example, the male posts could extend from the downstream member  34  into the upstream member  32 . Each support  32  and  34  could include both posts and apertures for engaging a corresponding pattern in the opposing support. The apertures do not have to extend through to the opposite side of the defining support. Also, one or both supports could employ magnets that cause the two supports  32  and  34  to be attracted to each other across the leaflet tissue  3 .  
         [0040]    The support  10  of FIG. 10 also includes a hinge assembly  42 , however an unhinged two-sided support is also considered within the scope of the present invention. The hinge assembly  42  includes a single hinge  24  on the downstream member  34 , which may be similar to the hinge shown in FIG. 7. The upstream member  32  includes two, or preferably three hinges  44  interconnected with connecting members  46 . The connecting members  46  add length to the hinge assembly  42  such that, when the support  10  bends to an open position, the upstream and downstream members  32  and  34  do not move relative to each other.  
         [0041]    [0041]FIG. 11 shows an alternative design for a support  10  that incorporates a substrate  48 . The substrate  48  is preferably a flexible, biocompatible fabric that is at least somewhat resistant to stretching and compressing. The substrate is curved around a longitudinal axis  50  to form a concave side  52  and a convex side  54 . The curve is imparted to the substrate  48  using a heat, mechanical, or chemical forming process. Alternatively, or additionally, a curved brace  56  is included at one end of the support  10  that is to be placed near the base of the valve leaflet, proximal the arterial wall.  
         [0042]    Imparting a curve around the longitudinal axis  50  provides a directional strength to the support  10  that lends itself to the application of supporting a prolapsed valve leaflet. As seen in FIG. 12, when blood flows in a systolic direction, the blood pushes on the convex side  54  of the support  10  and causes the support to buckle, allowing the blood to pass through the valve. The curve does not add significant strength to the support  10  in this direction. However, when the pressure reverses, such as during diastole, the support  10  snaps back into the closed position shown in FIG. 11. Pressure against the concave side  52  is met with the resistance imparted to the support  10  by the curve, preventing the support  10  from buckling toward the convex side  54 .  
         [0043]    The support  10  of FIGS. 11 and 12 is versatile enough to be placed on either or both sides of a prolapsed valve. Attachment mechanisms such as staples, permanent sutures, adhesives, magnets, or the like could be used to secure the support  10  to the valve leaflet.  
         [0044]    [0044]FIG. 13 shows another embodiment of a support  10  attached to a prolapsed valve leaflet  3 . The support  10  includes a network  58  of interconnected structures  60 . The structures  60  are constructed and arranged to allow the support  10  to bend in a downstream direction to an open position, yet provides resistance to bending in an upstream direction during a diastole. The support  10  may include a covering over the network  58  or the network  58  may remain open.  
         [0045]    A method of securing a support  10  to a prolapsed valve leaflet  3  is illustrated in FIGS. 14 a - d . A guide wire  62  is threaded through a blood vessel  4  to the site where the support  10  is to be installed. A catheter sheath  64 , containing the support  10 , is then fed along the guide wire  62  until the valve  1  is reached and the support  10  is adjacent the target leaflet  3 . The sheath  64  is then carefully retracted until the support  10  is exposed and free to rotate.  
         [0046]    The support  10  is attached at one end to a delivery mechanism  66 , best shown in FIGS. 15 and 16. The delivery mechanism  66  is used to rotate the support  10  into place after the sheath  64  is removed. Rotation is achieved by manually pulling on activation strings  68 . When the strings  68  are pulled, the delivery arms  70  rotate around axles  72  in the directions shown by arrows  74  (FIG. 14 d ). The support  10 , being temporarily attached to the delivery arms  70 , rotate therewith. It may be necessary to hold a carrier  76 , on which the arms  70  are pivotally mounted, when pulling the strings  68 , in order to maintain the position of the delivery mechanism  66 . Once in place, the attachment mechanism of the support penetrates the leaflet, or otherwise fixes the support  10  to the leaflet, and allows the delivery arms  70  to be dislodged from the support  10 . The delivery mechanism  66  and guide wire  62  are then retracted into the sheath  64  and the sheath  64  is removed from the patient.  
         [0047]    The delivery mechanism  66  is shown in FIG. 15 as delivering a support  10  that includes both an upstream member  32  and a downstream member  34 . However, the same delivery mechanism  66 , having two delivery arms  70 , could also be used to deliver supports having only one support member, either upstream or downstream. The unused arm  70  provides a surface against which the other arm acts to secure the support to the leaflet. The unused arm also provides a surface against which staples, if used as an attachment mechanism, can be folded into an attached arrangement.  
         [0048]    The foregoing description addresses embodiments encompassing the principles of the present invention. The embodiments may be changed, modified and/or implemented using various types of arrangements. Those skilled in the art will readily recognize various modifications and changes that may be made to the invention without strictly following the exemplary embodiments and applications illustrated and described herein, and without departing from the scope of the invention, which is set forth in the following claims.