Abstract:
A prosthetic valve assembly that includes a stent, a tissue sleeve and an anchoring mechanism. By loading the three components of the valve assembly into a delivery catheter in a series formation, such that no two components are located within each other, the size of the delivery catheter can be reduced.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/593,817 filed Feb. 1, 2012 entitled Invertable Tissue Valve, which is hereby incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Replacing heart valves with prosthetic valves was, until recently, a complicated surgical procedure that involved cutting open the chest, establishing blood flow through a blood pump, stopping the heart, etc. This complicated procedure, even when performed perfectly, required extensive recovery time due to the invasiveness and damage done to access the implantation site. Additionally, the risk of infection or other complications is extremely high. 
         [0003]    Numerous advancements have been made to develop prosthetic valves that can be implanted percutaneously, using a catheter to snake the prosthetic valve through the vasculature to the implantation site. If successful, the recovery time is greatly minimized relative to conventional open-heart surgery. 
         [0004]    A designer of a percutaneously-delivered prosthetic valve is faced with numerous challenges, however. First and foremost is designing a prosthetic valve that can be compressed enough to be inserted into a catheter small enough to be navigated to the valve site through the vasculature. Other challenges include anchoring the valve at the valve site so the valve does not migrate after release; including a support structure for the valve that is robust enough to push the native, often calcified valve out of the way and prevent it from later interfering with the function of the new valve; ensuring that the new valve allows proper flow in a desired direction and effectively stops flow in the opposite direction; ensuring that no blood flows around the sides of the implanted device (this is known as perivalvular leakage); designing a prosthetic valve device that does not fail due to fatigue after hundreds of thousands of cycles of leaflet function; designing a valve that meets all of these criteria and can still be manufactured economically; and the list goes on. 
         [0005]    These prosthetic valves, and their respective delivery catheters, are designed to replace a particular native valve. One native valve that presents unique challenges is the aortic valve. The aortic valve controls blood flow from the left ventricle into the aorta. Reaching the aortic valve percutaneously is typically accomplished using one of two approaches. 
         [0006]    The first approach is a transfemoral retrograde approach whereby the femoral artery is accessed near the groin of the patient, and followed upstream to the aortic valve. The transfemoral approach is retrograde because travel is against the flow of blood and thus the downstream side of the aortic valve is reached first. 
         [0007]    The second approach is a transapical antegrade approach which can be performed via a left anterolateral minithoracotomy. This approach punctures the apex of the heart to provide direct access to the left ventricle. Thus, the aortic valve is approached from the upstream (antegrade) side. 
         [0008]    There are advantages and disadvantages to both approaches. The transfemoral approach is considered less invasive because the heart is not punctured. However, the navigation is much longer and access to the aortic valve requires the necessarily longer delivery catheter to follow the curve of the aortic arch at the end of the path to the valve. Thus, the delivery catheter must be more maneuverable and the prosthetic valve must not interfere with the maneuverability of the catheter while the valve is loaded into it. The transapical approach requires puncturing the myocardial sac and the apex of the heart and traversing the chest cavity. In each of these cases, the heart is beating as well, adding more difficulty to the procedure. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0009]    One aspect of the invention is directed to a prosthetic valve device for use in replacing a native aortic valve using a retrograde approach. 
         [0010]    Another aspect of the invention is directed to a prosthetic valve device that is sized to replace an aortic valve and capable of being delivered using a small, flexible catheter. 
         [0011]    Another aspect of the invention is directed to a prosthetic valve device that comprises two components positioned in series (spaced apart axially) in a delivery catheter to reduce the size of the delivery catheter required. 
         [0012]    Another aspect of the invention is directed to a prosthetic valve device that comprises two components positioned in series during navigation whereby the two components can be located together upon delivery to the target site. 
         [0013]    One aspect of the invention provides a device for replacing a native valve comprising: a stent; a tissue sleeve; and, an anchoring mechanism usable to secure said tissue sleeve within said stent; wherein, in a configuration inside a delivery catheter, said anchoring mechanism is not located within said stent; and wherein, in a deployed configuration, said tissue sleeve is located within said stent. 
         [0014]    Another aspect of the invention provides that said tissue sleeve is inverted (i.e. inside-out) relative to said configuration inside said delivery catheter. 
         [0015]    Another aspect of the invention provides that the tissue sleeve is connected to said stent at a first end and connected to said anchoring mechanism at a second end, opposite said first end. 
         [0016]    Another aspect of the invention provides an anchoring mechanism that comprises a wireform. 
         [0017]    Another aspect of the invention provides an anchoring mechanism that comprises a ring. 
         [0018]    Another aspect of the invention provides an anchoring mechanism that comprises a ring and a wireform. 
         [0019]    Another aspect of the invention provides an anchoring mechanism that comprises a ring attached to a first end of said tissue sleeve and a second ring attached to an opposite side of said tissue sleeve. 
         [0020]    Another aspect of the invention provides a tissue sleeve that comprises valve leaflets. 
         [0021]    Another aspect of the invention provides a tissue sleeve that comprises pinch points that result in the formation of valve leaflets when implanted. 
         [0022]    Another aspect of the invention provides a method for replacing a native blood valve comprising: expanding a stent within said native valve; anchoring a tissue sleeve at a proximal end of said stent; advancing said tissue sleeve into said stent, resulting in an inversion of said tissue sleeve; and allowing blood to flow through said tissue sleeve in a proximal direction while not allowing blood to flow through said tissue sleeve in a distal direction. 
         [0023]    In one aspect of the invention a method is provided wherein expanding a stent within said native valve comprises expanding a stent within said native valve prior to introducing said tissue sleeve at a proximal end of said stent. 
         [0024]    In another aspect of the invention a method is provided wherein anchoring a tissue sleeve at a proximal end of said stent occurs prior to the step of expanding a stent within said native valve. 
         [0025]    In another aspect of the invention a method is provided wherein anchoring a tissue sleeve at a proximal end of said stent comprises attaching said tissue sleeve to said proximal end of said stent. 
         [0026]    In another aspect of the invention a method is provided wherein anchoring a tissue sleeve at a proximal end of said stent comprises allowing a ring to expand at a proximal end of said stent, said ring attached to said tissue sleeve. 
         [0027]    In another aspect of the invention a method is provided wherein allowing blood to flow through said tissue sleeve in a proximal direction while not allowing blood to flow through said tissue sleeve in a distal direction comprises providing valve leaflets attached to said tissue sleeve such that said valve leaflets are located on an outside surface of said tissue sleeve prior to said inversion and on an inside of said tissue sleeve after inversion. 
         [0028]    In another aspect of the invention a method is provided wherein allowing blood to flow through said tissue sleeve in a proximal direction while not allowing blood to flow through said tissue sleeve in a distal direction comprises expanding a wireform within said tissue sleeve, said wireform creating valve leaflets in said tissue sleeve when expanded. 
         [0029]    In another aspect of the invention a method is provided wherein allowing blood to flow through said tissue sleeve in a proximal direction while not allowing blood to flow through said tissue sleeve in a distal direction comprises providing pinch points in a proximal end of said tissue sleeve, after said tissue sleeve is inverted, said pinch point causing blood flow to form valve leaflets out of said tissue sleeve when blood is flowing in a distal direction. 
         [0030]    In another aspect of the invention a method is provided further comprising the step of anchoring said tissue sleeve near a distal end of said stent after the step of advancing said tissue sleeve into said stent. 
         [0031]    One aspect of the invention provides a valve assembly for implantation within a stent comprising: a tissue sleeve; at least one anchoring mechanism for securing said tissue sleeve within said stent; wherein said tissue sleeve is connected to said at least one anchoring mechanism. 
         [0032]    Another aspect of the invention provides a valve assembly wherein said tissue sleeve is attached to a proximal end of said stent. 
         [0033]    Another aspect of the invention provides a valve assembly wherein said at least one anchoring mechanism comprises a wireform. 
         [0034]    Another aspect of the invention provides a valve assembly wherein said at least one anchoring mechanism comprises at least one expandable ring. 
         [0035]    Another aspect of the invention provides a valve assembly wherein said at least one expandable ring comprises a first expandable ring at one end of said tissue sleeve and a second expandable ring at another end of said tissue sleeve. 
         [0036]    Another aspect of the invention provides a valve assembly wherein said tissue sleeve comprises valve leaflets. 
         [0037]    Another aspect of the invention provides a valve assembly wherein said tissue sleeve forms valve leaflets when said at least one anchoring mechanism is expanded. 
         [0038]    Another aspect of the invention provides a valve assembly wherein said tissue sleeve comprises valve leaflets that become function after said tissue sleeve is inverted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which 
           [0040]      FIG. 1  is a side view of an embodiment of the invention; 
           [0041]      FIGS. 2A-2D  illustrate a delivery sequence for the embodiment of  FIG. 1 ; 
           [0042]      FIGS. 3A-F  illustrate a delivery sequence for an embodiment of the invention; 
           [0043]      FIG. 4  is a side view of an embodiment of the invention; 
           [0044]      FIG. 5  is a side view of an embodiment of the invention; 
           [0045]      FIG. 6  is a side view of an embodiment of the invention; 
           [0046]      FIGS. 7A-D  illustrate a delivery sequence for an embodiment of the invention; 
           [0047]      FIGS. 8A-D  illustrate a delivery sequence for an embodiment of the invention; and 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0048]    Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
         [0049]    Referring first to  FIG. 1  there is shown a device  10  of the invention. Device  10  generally includes a stent  12  connected to a valve assembly that includes a valve frame  14  and tissue connectors  16 . Tissue  18  forms a prosthetic valve, shaped by the valve frame  14 . The tissue connectors act as a stop when the valve frame  14  is advanced into the stent  12  during delivery. Note that the tissue  18  between the stent  12  and the valve frame  14  prevents blood from flowing around the valve frame  14 . Thus perivalvular leakage is avoided. 
         [0050]    Thus, delivery of the device  10 , as illustrated in  FIGS. 2A-2D  would involve navigation a catheter  20  to the valve site ( FIG. 2A ), retracting a restraining sheath  22  until the stent  12  is released and allowed to expand ( FIG. 2B ), advancing the still-constrained valve frame  14  into the expanded stent  12  until the tissue connectors  16  prevent further distal movement ( FIG. 2C ), retracting the restraining sheath  22  until the valve frame  14  is released, allowing the valve frame  14  to expand within the stent  12  ( FIG. 2D ). 
         [0051]      FIGS. 3A-3E  illustrate an embodiment  30  of the invention wherein the stent  32  is balloon-expandable. Device  30  generally includes a stent  32  connected to a valve frame  34  with tissue connectors  36 . Tissue  38  forms a prosthetic valve, shaped by the valve frame  34 . The tissue connectors act as a stop when the valve frame  34  is advanced into the stent  32  during delivery. Note that the tissue  38  between the stent  32  and the valve frame  34  prevents blood from flowing around the valve frame  34 . Thus perivalvular leakage is avoided. 
         [0052]    Thus, delivery of the device  10 , as illustrated in  FIGS. 3A-3E  would involve navigation a catheter  20  to the valve site ( FIG. 3A ), retracting a restraining sheath  22  until the stent  32  is released ( FIG. 3B ), inflating a balloon  24  within the stent  32  to expand the stent  32  ( FIG. 3C ), deflating the balloon  24  ( FIG. 3D ), advancing the still-constrained valve frame  34  into the expanded stent  32  until the tissue connectors  36  prevent further distal movement ( FIG. 3E ), retracting the restraining sheath  22  until the valve frame  14  is released, allowing the valve frame  14  to expand within the stent  12  ( FIG. 3F ). 
         [0053]      FIG. 4  shows an embodiment  40  of a device of the invention. The device  40  shown in  FIG. 4  Device  40  includes a stent  42 , and a valve assembly that includes a wireform  44  and tissue  46 . Rather than sewing the tissue to the wireform  44 , thereby creating a valve frame for the prosthetic valve, the tissue  46  is attached to the wireform  44  at attachment points  50 . Valve leaflets  48  are incorporated into the tissue  46  spanning between the stent  42  and the wireform  44 . In the delivery configuration shown in  FIG. 4 , the valve leaflets are located on the outside of the tissue sleeve  46 . During delivery, using one of the procedures described above, as the wireform  44  is inserted inside the expanded stent  42 , the tissue  46  and the leaflets  48  are inverted (i.e. turned inside-out) so that the valve leaflets are on the inside of the tissue sleeve  46 . The wireform  44  is then expanded against the inside of the tissue sleeve  46 , and aligned with the valve leaflets  48  so as not to interfere with their function. Thus the tissue sleeve  46 , leaflets  48 , and wireform  44 , together form the prosthetic valve. 
         [0054]    Device  40  allows a prosthetic valve to be formed using significantly less tissue material, as there is no need for two layers of tissue around the perimeter of the device after implant. Additionally, device  40  makes it possible to establish flow regulation through the device even at the intermediate stage of device implant. 
         [0055]      FIG. 5  shows a device  60  that is similar to that of  FIG. 4  except that it does not include valve leaflets. The device  60  includes a stent  62 , and a valve assembly that includes a wireform  64 , and a tissue sleeve  66 . Tissue sleeve  66  is simply a tube of tissue. Once the device  60  is delivered, using any of the methods described above, the tissue sleeve  66  is inverted inside the stent  62  and the wireform  64  is expanded. When the wireform  64  is expanded inside the tissue sleeve  66 , the wireform  64  creates leaflets due to the shape of the wireform  64 . In this way, alignment of the wireform  64  inside the tissue sleeve  66  is not as critical as the embodiment  50  described above. Rather, one would merely need to ensure that there is enough tissue in the tissue sleeve  66  to effect coaptation of the resulting valve leaflets. 
         [0056]      FIG. 6  shows a device  70  that avoids the use of a wireform. The device  70  of  FIG. 6  generally includes a stent  72  and a valve assembly that includes an anchor ring  74  and a tissue sleeve  76  connecting the stent  72  and the anchor ring  74 . Upon deployment using any of the above methods, the stent  72  is expanded, the ring  74  is advanced into the stent  72 , inverting the tissue sleeve  76 , and the ring  74  is expanded. Pinch points  78  are formed in the tissue sleeve  76 . The pinch points  78  create the formation of valve leaflets once the device is inverted and subjected to blood flow. 
         [0057]    All of the devices heretofore described have been directed to designs that allow the device to be delivered in an axially, displaced, unassembled form and inverted and located upon delivery to create a finished device. These devices are thus directed toward a goal of being able to compress the devices into a small catheter, such as a  14  French catheter, for delivery. Potentially, however, areas where two components connect, such as the connection between the tissue sleeve and the stent, will have slight overlap that may result in additional thickness. Thus, the remaining embodiments described herein are directed to devices having stents and valves that are not connected to each other while they are inside the delivery catheter. 
         [0058]    For example, referring to  FIGS. 7A-D , there is shown a device  80  comprising two separate components: a stent  82  and a valve assembly  84 . The valve assembly  84  includes a self-expanding anchor ring  86 , a tissue sleeve  88  and a wireform  90 . The anchor ring  86  anchors the valve assembly  84  in place until the wireform  90  is delivered. The anchor ring  86  also ensures proper reverse flow into the valve to effect coaptation of the resulting leaflets. 
         [0059]    The delivery sequence for device  80  is as follows: As seen in  FIG. 7A , a stent  82  has been placed at the native valve site. The delivery catheter  20  is advanced until the distal end of the catheter is near of the proximal end of the stent  82 . The sheath  22  of the delivery catheter  20  is then retracted releasing the ring  86 . ( FIG. 7B ) The ring expands just outside, or just inside of the stent  82 . The delivery catheter  22  is advanced into the stent  82 , causing the tissue sleeve  88  to invert. ( FIG. 7C ) The wireform  90  is then released from the sheath  22  and allowed to expand inside the stent  82  ( FIG. 7D ) and delivery is complete. The position of the wireform  90  relative to the tissue sleeve  88  constrains the tissue in such a way that the tissue sleeve is formed into valve leaflets. Conversely, the wireform  90  may have tissue leaflets already mounted to it and the tissue sleeve  88  is used solely to prevent perivalvular leak. 
         [0060]      FIGS. 8A-D  show an embodiment  100  that does not use a wireform. Rather device  100  comprises two separate components: a stent  102  and a valve assembly  104 . The valve assembly  104  includes a first anchor ring  106 , a second anchor ring  108 , and a tissue sleeve  110  between the two anchor rings. The first anchor ring  106  anchors the valve assembly  104  in place to allow the tissue to be inverted. 
         [0061]    The delivery sequence for device  100  is as follows: As seen in  FIG. 8A , a stent  102  has been placed at the native valve site. The delivery catheter  20  is advanced until the distal end of the catheter is near of the proximal end of the stent  102 . The sheath  22  of the delivery catheter  20  is then retracted releasing the ring  106 . ( FIG. 8B ) The ring expands just outside, or just inside of the stent  102 . The delivery catheter  22  is advanced into the stent  102 , causing the tissue sleeve  110  to invert. ( FIG. 8C ) The second ring  108  is then released from the sheath  22  and allowed to expand inside the stent  102  ( FIG. 8D ) and delivery is complete. The tissue sleeve  110  may have attachment points at discrete multiple locations  112  around the circumference of the ring  106  in order to define the commissural points of the prosthetic tissue valve. 
         [0062]    Though expanding the first ring  106  on the aortic (proximal) side of the stent  102  may be advantageous in order to establish initial alignment, one could avoid the inversion step by deploying the first anchor ring  106  on the ventricular, or distal side of the sent  102  and then further retracting the sheath  22  until the second ring  108  is released and allowed to expand near the aortic side of the stent  102 . 
         [0063]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.