Patent Publication Number: US-2016220358-A1

Title: Delivery Tool For Percutaneous Delivery Of A Prosthesis

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 11/864,557 filed Sep. 28, 2007 entitled Delivery Tool For Percutaneous Delivery Of A Prosthesis, which claims priority to U.S. Provisional Application Ser. No. 60/827,373 filed Sep. 28, 2006 entitled Delivery Tool For Percutaneous Delivery Of A Prosthesis, both of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     There has been a significant movement toward developing and performing cardiovascular surgeries using a percutaneous approach. Through the use of one or more catheters that are introduced through, for example, the femoral artery, tools and devices can be delivered to a desired area in the cardiovascular system to perform any number of complicated procedures that normally otherwise require an invasive surgical procedure. Such approaches greatly reduce the trauma endured by the patient and can significantly reduce recovery periods. The percutaneous approach is particularly attractive as an alternative to performing open-heart surgery. 
     Valve replacement surgery provides one example of an area where percutaneous solutions are being developed. A number of diseases result in a thickening, and subsequent immobility or reduced mobility, of heart valve leaflets. Such immobility also may lead to a narrowing, or stenosis, of the passageway through the valve. The increased resistance to blood flow that a stenosed valve presents can eventually lead to heart failure and ultimately death. 
     Treating valve stenosis or regurgitation has heretofore involved complete removal of the existing native valve through an open-heart procedure 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. 
     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. On the other hand, a proposed percutaneous valve replacement alternative method is disclosed in U.S. Pat. No. 6,168,614, which is herein incorporated by reference in its entirety. In this patent, the prosthetic valve is mounted within a stent that 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 stent at the location of the native valve. A deployment mechanism is activated that expands the stent containing the replacement valve against the valve cusps. The expanded structure includes a stent configured to have a valve shape with valve leaflet supports that together 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. 
     More recent techniques have further improved over the drawbacks inherent in U.S. Pat. No. 6,168,614. For example, one approach employs a stentless support structure as seen in U.S. patent application Ser. No. 11/443,814, entitled Stentless Support Structure, filed May 26, 2006, the contents of which are herein incorporated by reference. The stentless support structure provides a tubular mesh framework that supports a new artificial or biological valve within a patient&#39;s vessel. The framework typically exhibits shape memory properties which encourage the length of the framework to fold back on itself at least once and possibly multiple times during delivery. In this respect, the framework can be percutaneously delivered to a target area with a relatively small diameter, yet can expand and fold within a vessel to take on a substantially thicker diameter with increased strength. 
     Typically, the stentless support structure is delivered at the location of a diseased or poorly functioning valve within a patient. The structure expands against the leaflets of the native valve, pushing them against the side of the vessel. With the native valve permanently opened, the new valve begins functioning in place of the native valve. Optimally placing the stentless support structure involves percutaneously passing the structure through the diseased valve, deploying a distal end of the structure until the distal end flares outwardly, then pulling the structure back through the diseased valve until the user can feel the flared distal end of the structure contact a distal side of the diseased valve. Once confident that the flared distal end of the structure is abutting a distal side of the diseased valve, the remaining portion of the structure is deployed within the diseased valve. 
     In any of the above mentioned percutaneous valve device implant procedures, a significant challenge to device function is accurate placement of the implant. If the structure is deployed below or above the optimal device position, the native valve leaflets may not be captured by the prosthetic support structure and can further interfere with the operation of the implant. Further, misplacement of the support structure may result in interference between the prosthetic device and nearby structures of the heart, or can result in leakage of blood around the structure, circumventing the replacement valve. 
     Accurate placement of these devices within the native valve requires significant technical skill and training, and successful outcomes can be technique-dependent. What is needed is a delivery tool for more reliably locating a target deployment area, for positioning a percutaneous aortic valve replacement device or other prosthetic device in which the device location during implantation is critical (e.g., an occluder for vascular atrial septal defects, ventricular septal defects, patent foramen ovale or perforations of the heart or vasculature), and for the subsequent deployment of such a device to provide more reliable implant outcomes. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention provides an expandable delivery tool for deploying a prosthesis device within a patient. The delivery tool has a generally elongated shape with an expandable distal end region that flares outward in diameter. 
     In one aspect, the delivery tool provides a tactile indication of a desired target area, such as a valve. For example, once expanded within a patient&#39;s vessel, the delivery device can be pulled proximally towards the user until it contacts a desired target valve. This contact is transmitted and thereby felt by the user on a proximal end of the device outside the patient, providing an indication that a desired target location has been located. 
     In another aspect, the delivery tool provides a stationary backstop against which a prosthesis can be deployed, further ensuring the prosthesis is delivered at a desired target location within the patient. For example, the expanded backstop of the delivery tool is positioned at a location just distal to a native valve within a patient. The prosthesis is deployed within the native valve and against the expanded backstop, ensuring the prosthesis maintains its intended target position within the native valve. 
     In yet another aspect, the delivery tool is used to further expand the prosthesis after deployment. For example, the expandable backstop is reduced in size to a desired expansion diameter (i.e., the diameter the user wishes to expand the prosthesis to), then pulled through the deployed prosthesis, causing the diameter of the prosthesis to expand. This expansion further anchors the prosthesis against the vessel, ensuring its position is maintained and minimal leakage occurs past the periphery of the prosthesis. Alternately, the distal end of the delivery tool can be expanded within the prosthesis to further expand the prosthesis within the patient&#39;s vessel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a side view of a delivery tool according a preferred embodiment of the present invention; 
         FIG. 2  illustrates a side view of the delivery tool of  FIG. 1 ; 
         FIG. 3  illustrates a perspective view of the delivery tool of  FIG. 1 ; 
         FIG. 4  illustrates a side view of a valve prosthesis according to a preferred embodiment of the present invention; 
         FIG. 5  illustrates a side view of a locking-pin mechanism connected to a support structure according to a preferred embodiment of the present invention; 
         FIG. 6  illustrates a magnified side view of the locking-pin mechanism of  FIG. 5 ; 
         FIG. 7  illustrates a side perspective view of the locking-pin mechanism of  FIG. 5 ; 
         FIG. 8  illustrates a bottom perspective view of the locking-pin mechanism of  FIG. 5 ; 
         FIG. 9  illustrates a side view of the delivery tool of  FIG. 1 ; 
         FIG. 10  illustrates a side view of the delivery tool of  FIG. 1 ; 
         FIG. 11  illustrates a side view of the delivery tool of  FIG. 1 , with a valve prosthesis in the initial stage of deployment; 
         FIG. 12  illustrates a side view of the delivery tool of  FIG. 1 , with the initial portion of the prosthesis further deployed; 
         FIG. 13  illustrates a side view of the delivery tool of  FIG. 1 , with the initial portion of the prosthesis further deployed; 
         FIG. 14  illustrates a side view of the delivery tool of  FIG. 1  and the prosthesis retracted into a simulated valve site; 
         FIG. 15  illustrates a side view of the delivery tool of  FIG. 1  with the prosthesis having been deployed into a simulated valve site; 
         FIG. 16  illustrates a side view of the delivery tool of  FIG. 1  having been relaxed from its expanded configuration; 
         FIG. 17  illustrates a perspective view of the delivery tool of  FIG. 1  with the prosthesis having been fully deployed; 
         FIG. 18  illustrates a perspective view of the delivery tool of  FIG. 1  being drawn within the prosthetic valve; 
         FIG. 19  illustrates a perspective view of the delivery tool of  FIG. 1  drawn into the prosthetic valve and expanded to provide a means for fully seating the device within the native valve; 
         FIG. 20  illustrates a perspective view of a prosthesis and the delivery tool of  FIG. 1 ; 
         FIG. 21  illustrates a side view of a prosthesis and the delivery tool of  FIG. 1  with the tool having been fully withdrawn from the prosthetic valve; 
         FIG. 22  illustrates a side view of a preferred embodiment of a delivery tool with mesh formed into an expanded shape constituting an inverted cone; 
         FIG. 23  illustrates a side view of a preferred embodiment of a delivery tool with mesh formed into a conical cup shape without inversion of the mesh layers; 
         FIG. 24  illustrates a side view of a preferred embodiment of the delivery tool constructed with a series of superelastic wire loops for location and placement; and 
         FIG. 25  illustrates a side view of a preferred embodiment of the delivery tool constructed with a series of balloons for location and placement. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an embodiment of an expandable delivery tool  100  according to the present invention. Generally, the expandable delivery tool  100  is removably positioned within the vessel of a patient to assist in the delivery and positioning of a prosthesis at a target area. In this respect, a user can more precisely deploy a prosthesis while minimizing unwanted deployment complications. 
     The expandable delivery tool  100  includes a deformable mesh region  102  that expands from a reduced diameter configuration seen in  FIG. 1  to a flared expanded diameter configuration seen in  FIGS. 2 and 3 . The diameter of the mesh region  102  is adjusted by increasing or decreasing the distance between a proximal and distal end of the mesh region  102 . More specifically, a distal anchor  104  secures the distal end of the mesh region  102  to a control wire  110  that extends through the mesh region  102  and proximally towards the user. An outer sheath  108  slides over the control wire  110  and is secured to the proximal anchor point  106 . Thus, the outer sheath  108  can be moved distally relative to the control wire  110  by the user to increase the diameter of the mesh region  102  and moved proximally relative to the control wire  110  to reduce the diameter of the mesh region  102 . 
     The mesh of the mesh region  102  may be created by braiding together a plurality of elongated filaments to form a generally tubular shape. These elongated filaments may be made from a shape memory material such as Nitinol, however non shape memory materials such as stainless steel or polymeric compounds can also be used. It should be noted that strength and shape of the mesh region  102  can be modified by changing the characteristics of the filaments. For example, the material, thickness, number of filaments used, and braiding pattern can be changed to adjust the flexibility of the mesh region  102 . 
     In a more specific example, the mesh region  102  of each filament has a diameter of 0.008″ and is made from Nitinol wire, braided at 8 to 10 picks per inch. This may result in an included braid angle between crossed wires of approximately 75 degrees. 
     While mesh is shown for the mesh region  102 , other materials or arrangements are possible which allow for selective expansion of this region while allowing profusion of blood past the delivery device  100 . 
     The maximum diameter of the expanded configuration of the mesh region  102  may be increased by increasing the length of the mesh region  102  and therefore allowing the ends of the mesh region  102  to be pulled together from a greater distance apart, or by decreasing the braid angle of the braided Nitinol tube. Similarly, the maximum diameter may be decreased by shortening the length of the mesh region  102  or by increasing the braid angle of the braided Nitinol tube. In other words, the length of the mesh region  102  and the braid angle used will generally determine the maximum expanded diameter that the mesh region  102  may achieve. Thus, the maximum diameter of the mesh region  102  can be selected for a procedure based on the diameter of the target vessel. 
     In the embodiments shown, the proximal anchor  106  and the distal anchor  104  are metal bands that clamp the mesh region  102  to the outer sheath  108  and control wire  110 , respectively. However, other anchoring methods can be used, such as an adhesive, welding, or a locking mechanical arrangement. 
     The proximal and distal ends of the mesh region  102  may include radiopaque marker bands (not shown) to provide visualization under fluoroscopy during a procedure. For example, these radiopaque bands may be incorporated into the mesh region  102  or may be included with the proximal and distal anchors  106  and  104 . In this respect, the user can better observe the position of the mesh region  102  and its state of expansion within the patient. 
       FIG. 4  illustrates an example of a prosthesis that can be delivered and positioned with the delivery device  100 . Specifically, the prosthesis is a stentless support structure  120  as seen in U.S. patent application Ser. No. 11/443,814, entitled Stentless Support Structure, filed May 26, 2006, the contents of which are herein incorporated by reference. 
     As described in the previously incorporated U.S. patent application Ser. No. 11/443,814, the support structure  120  is typically inverted or folded inward to create a multilayer support structure during the delivery. To assist the user in achieving a desired conformation of the support structure  120 , the delivery catheter typically includes connection members or arms that removable couple to the eyelets  132  of the support structure  120 . In this respect, the user can manipulate the support structure  120 , disconnect the connection members and finally, remove the delivery catheter from the patient. 
       FIGS. 5-8  illustrate a preferred embodiment of a removable coupling mechanism between a connection member  124  of a delivery catheter and the support structure  120 . Specifically, a locking-pin mechanism  130 , best seen in  FIGS. 7 and 8 , includes a first jaw member  136  having a locking pin  134  and a second jaw member  138  having an aperture  140  to capture the locking pin  134  when the locking pin mechanism  130  is closed. The jaw members  136  and  138  can be moved between open and closed positions (i.e., unlocked and locked positions) by adjusting control wires (or alternately rods) slideably contained within the connection member  124 . The distal ends of the control wires are connected to the jaw members  136  and  138 , causing the jaw members  136  and  138  to move near or away from each other. 
     As best seen in  FIGS. 5 and 6 , the locking-pin mechanism  130  passes through the eyelet  132  of the support structure  120 . When the locking-pin mechanism  130  is in the closed position, the eyelet  132  is locked around the connection member  124 . When the user wishes to release the support structure  120 , the jaw members  136  and  138  are opened allowing the eyelet  132  to slide off of the locking pin  134 . In this respect, the user can selectively release the support structure  120  by moving the control wires from a proximal location outside the body. 
     Preferably, the locking pin  134  has a longitudinal axis that is perpendicular to the longitudinal axis of the connection member  124 . Because the locking pin  134  is supported by both jaws  136  and  138  when the mechanism  130  is in the closed position, and because the resulting force placed on the locking pin  134  is normal to the longitudinal axis of the locking pin  134 , the locking-pin mechanism  130  is not urged toward the open position when under load. Accordingly, the locking-pin mechanism  130  provides a strong and unbreakable connection with the eyelet  132  until the user disengages the locking-pin mechanism  130  from the eyelet  132  by opening the jaws  136 ,  138 . 
     One advantage of the configuration of the connection member  130  and the location of the eyelets  132  is that even when all three connection members  130  are attached to the eyelets  132  (see, e.g.,  FIG. 21 ), there is no interference between the connection members  130  and the operation of the valve leaflets  125 . Additionally, blood may flow around the delivery mechanism and through the prosthesis. Hence, the operation and location of the prosthesis may be verified prior to release. If the position of the prosthesis is undesirable, or if the valve leaflets  125  are not operating, the prosthesis may be retracted into the delivery mechanism. 
     Alternately, other coupling mechanisms can be used to retain and release the support structure  120 . For example, the connection member  124  may have hooks or breakable filaments at their distal end which allow the user to selectively release the support structure  120 . 
     Operation of the device is now described in detail. Referring to  FIGS. 9-21 , the delivery tool  100  is illustrated delivering a prosthesis to a piece of clear tubing that represents a native valve  114  (e.g., aortic valve) within a patient. In this example, the prosthesis is the previously described stentless support structure  120 . However, it should be understood that the present invention can be used for the delivery of a variety of prosthesis devices including stent devices as seen in the previously discussed Andersen &#39;614 patent, as well as other devices used for occlusion of apertures or perforations of the heart or vasculature. 
     A distal end of a guidewire and introducer (not shown in the Figures) are typically advanced to the desired target area in the patient&#39;s vessel. In this case the target area is a native valve  114 . Next, a delivery sheath  112  is slid over the guide catheter until its distal end is at the approximate location of the delivery sheath  112 , and the guidewire and introducer are removed. 
     Referring now to  FIG. 9 , the delivery tool  100  is advanced through the delivery sheath  112  until the mesh region  102  exits from the distal end of the delivery sheath  112  and passes to a location distal to the target area (i.e., past the target location which in this example is the native valve  114 ). 
     Turning now to  FIG. 10 , the user moves the delivery tool  100  into its expanded configuration by pulling on the proximal end of the control wire  110  relative to the outer sheath  108 . This moves the distal end of the control wire  108  towards the end of the outer sheath  108 , compressing the length of the mesh region  102  while increasing or flaring its diameter. 
     As seen in  FIG. 11 , a stentless support structure  120  (for anchoring a replacement valve) is advanced out of the distal end of the delivery sheath  112  until it contacts the mesh region  102  of the delivery tool  100 . As it continues to advance from the delivery sheath  112 , the support structure  120  expands in diameter as seen in  FIGS. 12 and 13 . In this respect, the support structure  120  becomes at least partially or even fully deployed distally to the native valve  114 . 
     Next, the stentless support structure  120  is advanced from the delivery sheath  112  by multiple connection members  124 , seen best in  FIGS. 18, 20 and 21 . Each of the connection members  124  are removably connected to the stentless support structure  120  at their distal ends and are longitudinally slidable within the delivery sheath  112 . In this respect, the user can manipulate a proximal exposed end of the connection members  124  to advance and further position the stentless support structure  120 , even after the structure  120  has been partially deployed. Once the stentless support structure  120  has achieved a desired position, and the operation of the prosthesis has been verified, the connection members  124  can be uncoupled from the structure  120  and removed from the patient. 
     Turning to  FIG. 14 , both the delivery tool  100  and the stentless support structure  120  are retracted in a proximal direction towards the native valve  114 . As the delivery tool  100  retracts, the expanded diameter of the mesh region  102  contacts the native valve  114  to provide the user with a tactile indication. Thus, the user is alerted when the support structure  120  achieves the desired target location within the native valve  114 . 
     As previously described in this application, the stentless support structure  120  is folded inwards on itself to create a dual layer (or even a multiple layer) support structure. This folding configuration allows the stentless support structure  120  to achieve a relatively small delivery profile within the delivery sheath  112  while deploying to have increased wall thickness. While this folding may generally occur by itself due to the preconfigured characteristics of the shape memory material of the support structure  120 , additional force in a distal direction may be required to assist the support structure  120  in achieving its final configuration. Typically, this extra force may be generated by advancing the delivery sheath  112  relative to the support structure  120  (i.e., pushing the delivery sheath  112  or by advancing the connection members  124 ). However, this extra movement by the delivery sheath can dislodge the support structure  120  from the native valve  114 , particularly in a distal direction. 
     To prevent the aforementioned movement of the support structure  120 , the expanded mesh region  102  is held in place against the edge of the native valve  114 , preventing the support structure  120  from dislodging. In other words, the mesh region  102  of the delivery device  100  acts as a stationary backstop, preventing distal movement of the support structure out of the native valve  114  and therefore allowing the user to more precisely determine the deployed location of the support structure  120  within the patient. 
     In some circumstances, a user may simply wish to adjust the mesh region  102  to its contracted configuration and remove the delivery device from the patient. In other circumstances, the user may wish to further expand the support structure  120  to provide additional anchoring force against the native valve and to ensure that the leaflets of the native valve remain captured under the support structure  120 . 
     The further expansion of the support structure  120  can be achieved with the mesh region  102  of the delivery tool  100 , similar to a balloon catheter. More specifically, the delivery tool  100  is advanced in a distal direction away from the native valve  114 , as seen in  FIG. 15 . As seen in  FIGS. 16 and 17 , the diameter of the mesh region  102  is reduced to a desired target diameter of the support structure  120  (i.e., the diameter the user wishes to expand the support structure  120  to). 
     Referring to  FIGS. 18 and 19 , once the desired diameter of the mesh region  102  has been achieved, the user retracts the delivery device  100  in a proximal direction through the support structure  120  which causes the support structure  120  to further expand against the native valve  114 . The resulting expansion of the support structure  120  can be better demonstrated by comparing the perspective view of  FIG. 17  to the view shown in  FIG. 20 . 
     Once the delivery device has been pulled all the way through the support structure  120  and the native valve  114 , as seen in  FIG. 21 , the mesh region  102  can be further reduced in diameter and removed from the patient. Finally, the connection members  124  can be disconnected from the support structure  120  and removed with the delivery sheath  112 . 
     Alternately, this same expansion of the support structure  120  can be achieved by initially decreasing the diameter of the mesh region  102 , positioning the mesh region  102  within the support structure  120 , then expanding the mesh region  102  to a desired diameter. Once a desired expansion of the support structure  120  has been achieved, the mesh region  102  can be decreased in diameter and pulled out of the patient. 
     Other embodiments of the present invention may include a configuration of the mesh region that forms a variety of shapes in the expanded profile and can be used for other applications (e.g., implantable prosthetic devices having similar or different shapes or structures than the support structure  120 ). For example,  FIG. 22  illustrates a delivery device  200  generally similar to the previously described delivery device and further includes an inverted cone shape mesh region  202  connected to an outer sheath  204 . In this respect, the mesh region  202  may be selectively expanded to a cone shape for delivery of a support structure. 
     Additionally, a pig tail  206  can be included on the end of the outer sheath  204  or distal end of the delivery device  200  to act as a bumper, thereby minimizing potential damage that may otherwise be caused by the distal end of the device  200  during delivery. The pigtail may be composed of a short tube composed of a flexible polymer and has a generally curved or circular shape. 
     In another example,  FIG. 23  illustrates a delivery device  300  including a conical cup shaped mesh region  302  which is generally similar to the previously described preferred embodiments  100  and  200 . Similarly, the device  300  includes an outer sheath  304  and a pig tail  306  on the distal end of the device  300  to prevent damage to the patient. However unlike the relatively flat distal end of the delivery device  200 , the delivery device  300  inverts to form a cup shape having an open, distal end. 
     As seen in  FIG. 24 , a distal end of a delivery device  400  may be constructed with individual arms  401  built from flexible or superelastic wire  402 . These arms  401  can be expanded and contracted similar to the previously described embodiments and may also include a pigtail  406  disposed at a distal end of the outer sheath  404  or delivery device  400 . 
     Referring to  FIG. 25 , a distal end of a delivery device  500  may alternately include a series of expandable balloons  502  linked together to a catheter  504  to provide delivery and positioning functions similar to the previously described embodiment while allowing blood flow through the balloon interstices. The balloons  502  may be inflatable and may be further expandable relative to each other by a mechanism similar to the previously described embodiments. Further, a pigtail may be included on the distal end of the delivery device  500 . 
     While a stentless support structure  120  has been described with regards to the Figures, other prosthesis devices may similarly be delivered with the present invention. For example, the delivery tool  100  may be used to deploy a stent with an attached replacement valve at a poorly functioning target valve. Additionally, this device may be used independently as a tool to perform balloon aortic valvuloplasty or other balloon techniques in which, for example, device porosity and blood flow-through are desired during the procedure. 
     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.