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 
     This application claims benefit of and priority to U.S. Provisional Application Ser. No. 61/800,153 filed Mar. 15, 2013 entitled Low-Profile Prosthetic Valve Structure, which is hereby incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     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. 
     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. 
     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. 
     These prosthetic valves, and their respective delivery catheters, are designed to replace a particular native valve, such as the aortic valve, for example. Percutaneous navigation to a valve is easiest, and least traumatic to the patient, when a smaller catheter is used. Smaller catheters, however, present challenges when designing effective prosthetic valves that can be compressed enough to fit, and slide, within the lumen of a small catheter, such as a 16 Fr or even a 14 Fr catheter. Significant strides have been made in recent years in designing prosthetic valves that have reduced profiles when in a catheter-loaded configuration. For example, the devices described in U.S. Patent Publication Number 2006/0271166 to Thill et al., the contents of which are incorporated by reference herein, can assume an elongated, unfolded configuration when loaded into a catheter and, when released from the catheter at a target site, resume a folded configuration. The present invention is directed to taking this innovative concept and presenting additional ways that the loaded configuration could present an even lower profile. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     One aspect of the invention is directed to a prosthetic valve device that presents a low profile in a catheter-loaded configuration. 
     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. 
     Another aspect of the invention is directed to a prosthetic valve device that comprises two components are connected but positioned in series (spaced apart axially) in a delivery catheter to reduce the size of the delivery catheter required. 
     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. 
     Another aspect of the invention provides prosthetic valve device that comprises a braided anchoring mechanism connected at a proximal end to a wireform. 
     Another aspect of the invention provides an implantable device that includes a support structure having an extended configuration and a folded configuration, the support structure having a first end, a second end and a preformed fold between said first end and said second end, wherein said preformed fold at least assists in inverting said first portion into said second portion when said support structure is released from a delivery device, and a prosthetic valve structure including a hinged end hingedly attached to said support structure first end, thereby allowing said support structure first portion to invert into said support structure second portion without inverting said prosthetic valve structure. 
     Another aspect of the invention provides an implantable prosthetic valve structure with a support structure that has a folded configuration in which the prosthetic valve structure extends, at least partially, into said support structure. 
     Another aspect of the invention provide a prosthetic valve device that includes a support structure that has inwardly curved sidewalls when it is in a folded configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 
         FIG. 1  is an elevation of an embodiment of the invention; 
         FIG. 2  is an elevation of an embodiment of the invention in a folded configuration; 
         FIG. 3  is a partial view of an embodiment of the invention; 
         FIG. 4  is a partial view of an embodiment of the invention; and 
         FIG. 5  is a partial view of an embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     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. 
     Referring first to  FIG. 1  there is shown a device  10  of the invention. Device  10  generally includes a support structure  20 , a valve assembly  40 , and a connection  60  between the support structure  20  and the valve assembly  40 .  FIG. 1  shows the device  10  in an elongate configuration prior to being compressed in order to fit within the lumen of a delivery catheter. It can be seen that the support structure  20 , the valve assembly  40 , and the connection mechanism  60  are all linearly arranged along a longitudinal axis in a series configuration, with no overlapping of components. 
     With regard to the support structure, a dotted line  22  represents a preformed fold created in the support structure  20  that at least partially causes the device  10  to fold inwardly on itself when released from a delivery catheter. The support structure  20  can be described as having a first end  24 , a first portion  26  between the first end  24  and the preformed fold  22 , a second end  30 , and second portion  32  between the second end  30  and the preformed fold  22 . 
     The valve assembly  40  includes tissue valve  42  attached to a wireform  44 . The wireform  44  gives structural integrity to the tissue valve  42 . 
     The connection  60  between the valve assembly  40  and the support structure  20  is described in more detail below. 
       FIG. 2  shows the device  10  of  FIG. 1  in a fully expanded, delivered configuration. The device  10  has folded inwardly on itself such that the fold  22  is now defining the proximal end of the support structure  20 . As the device  10  folded, the wireform  40 , which contains a tissue valve  42 , is drawn into the support structure  20 . Because the first portion  26  is now inverted, in other words, it is inside-out in comparison to its prefolded configuration of  FIG. 1 , the connection mechanism  60  must hinge or pivot in order to maintain the orientation of the valve assembly  40 . Because the connection mechanism  60  hinges, when the first portion  24  inverts into the second portion  32 , the valve assembly  40  moves only linearly (axially) into the support structure  20 , as shown by the arrow  100  in  FIG. 2 . Thus, only one preformed fold  22  is needed in the support structure  20  to allow the valve assembly  40  to maintain its orientation while moving axially. 
       FIG. 3  shows an embodiment of a connection mechanism  60 . The connection mechanism  60  may be a link  62  having two ring connectors  64  separated by a spacer  66 . The spacer  66  is sized to ensure that, in the elongated configuration, the connection mechanism  60  adequately separates the support structure  20  from the valve assembly  40 . The connection mechanism  60  may be constructed of a variety of bio-compatible material such as an alloy, including but not limited to stainless steel and Nitinol, or may be a polymer or other suitable non-metallic material. 
       FIG. 4  shows another embodiment of a connection mechanism  60 . This connection mechanism  60  may be a tether  70  having ends  72  that are tied to the wireform  44  of the valve assembly  40  and to the support structure  20 . The tether may be constructed of any suture material or may be a wire having suitable flexibility to be tied in a knot. The length of the tether  70  between the tied ends  72  constitutes a spacer  74  that is sized to ensure adequate separation of the support structure  20  from the valve assembly  40  in the elongated configuration of  FIG. 1 . 
       FIG. 5  shows an embodiment of a connection mechanism  60  that is a single loop  80 . The loop  80  extends around the wireform  44  and a strand of the support structure  20 . The loop  80  is sized to ensure adequate separation of the support structure  20  from the valve assembly  40  in the elongated configuration of  FIG. 1 . 
     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.