Abstract:
A device for repositioning an implant within a lumen of a subject including (a) a catheter having forward and rearward ends and a collapsible and expansible stop element mounted adjacent the forward end of the catheter, the stop element being adapted to engage a wall of the lumen when expanded and to provide one or more passages extending from a rear side of the stop element to a forward side of the stop element when the stop element is expanded and engaged with the wall of the lumen and (b) one or more snares, each snare having engagement features, the stop element and the snares being constructed and arranged so that the snares can be positioned extending through the one or more passages with their engagement features forward of the stop element.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/771,493 filed Mar. 1, 2013, the disclosure of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present invention relates to devices and methods for repositioning of collapsible prosthetic heart valves. 
         [0003]    Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery. 
         [0004]    Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two types of stents on which the valve structures are ordinarily mounted: a self-expanding stent or a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size. 
         [0005]    When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient&#39;s heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the entire valve, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn. 
         [0006]    Despite the various improvements that have been made to the collapsible prosthetic heart valve delivery process, conventional delivery devices, systems, and methods suffer from several shortcomings. For example, in conventional delivery devices for self-expanding valves, clinical success of the valve is dependent on accurate positioning, anchoring and acceptable valve performance. Inaccurate positioning increases risks such as valve migration, which may result in severe complications due to obstruction of the left ventricular outflow tract and may even result in patient death. Inaccurate positioning may further limit proper performance of the valve assembly. Additionally, improper positioning of a prosthetic heart valve may cause extended compression and/or stent deformation that affect valve durability. 
         [0007]    In conventional devices, once the prosthetic heart valve has been fully deployed, it is difficult to reposition the valve without resheathing the valve and redeploying. One risk in repositioning a fully deployed valve is pushing the prosthetic heart valve into a dangerous location such as, for example, the ascending aorta due to lack of control. 
         [0008]    There, therefore, is a need for further improvements to the devices, systems, and methods for transcatheter delivery and positioning of collapsible prosthetic heart valves. Specifically, there is a need for further improvements to the devices, systems, and methods for accurately positioning a prosthetic heart valve within the vasculature of a patient. Such positioning devices will help to reduce the risks associated with valve migration and improper valve positioning. Among other advantages, the present invention may address one or more of these needs. 
       SUMMARY OF THE INVENTION 
       [0009]    In some embodiments, a method of repositioning an implant engaged in a lumen of a mammalian subject includes (a) inserting an expansible stop element into the lumen and expanding the stop element into engagement with a wall of the lumen at a location offset from the implant, (b) inserting one or more snares into the lumen and engaging the snares with the implant, (c) while the snares are engaged with the implant, moving the snares so as to move the engaged implant toward the stop element and (d) disengaging the snares from the implant and removing the snares and stop element from the lumen. 
         [0010]    In some examples, the step of moving the snares is performed so as to move the implant into abutment with the stop element. The implant may include a stent and the step of engaging the snares with the stent includes engaging the snares with the stent. The implant may include a valve mounted to the stent for controlling flow through the lumen. The lumen may be a blood vessel. The lumen may be the aortic root. The stop element may define one or more passages through the stop element, and step (b) may include advancing the snares through the one or more passages. In some examples, when the stop element is in an expanded state and engaged with the wall of the lumen, the stop element may define one or more passages between the stop element and the wall of the lumen, and step (b) may include advancing the snares through the one or more passages. 
         [0011]    In some examples, the stop element may include a stop balloon and the step of expanding the stop element into engagement with the wall of the lumen may include inflating the balloon. The method may further include a conduit in fluid communication with the inside of the stop balloon for delivering a fluid to inflate the stop balloon. The one or more snares may include a plurality of snares connected to an elongated probe and step (b) includes advancing the probe in a forward direction through the lumen while the snares are in collapsed condition with engagement features on the snares adjacent one another and then moving the snares relative to the probe so as to spread the engagement features of the snares away from one another in lateral directions transverse to the forward direction. 
         [0012]    In some examples, the step of moving the snares relative to the probe includes inflating a spreader balloon disposed between the snares. The step of moving the snares and the implant toward the stop element may include operating a movement element connected between the snares and the probe to move the snares relative to the probe in a rearward direction opposite to the forward direction. 
         [0013]    In some embodiments, a device for repositioning an implant within a lumen of a subject may include (a) a catheter having forward and rearward ends and a collapsible and expansible stop element mounted adjacent the forward end of the catheter, the stop element being adapted to engage a wall of the lumen when expanded and to provide one or more passages extending from a rear side of the stop element to a forward side of the stop element when the stop element is expanded and engaged with the wall of the lumen and (b) one or more snares, each snare having engagement features, the stop element and the snares being constructed and arranged so that the snares can be positioned extending through the one or more passages with their engagement features forward of the stop element and so that the snares can be engaged with the implant and retracted rearwardly relative to the stop element while the stop element is engaged with the wall of the lumen. 
         [0014]    In some example, the device may further include an elongated probe having forward and rearward ends, wherein the one or more snares includes a plurality of snares connected to the probe adjacent the distal end thereof. The catheter may define a bore extending forwardly and rearwardly, the one or more passages defined by the stop element include a main passage communicating with the bore of the catheter, and the probe and snares are arranged so that the forward end of the probe can be advanced through the bore and main passage. The one or more snares may include a plurality of snares connected to an elongated probe, the plurality of snares and the elongated probe being configured such that moving the snares relative to the probe spread the engagement features of the snares away from one another in lateral directions transverse to a forward direction. 
         [0015]    In some examples, the device may further include a spreader balloon disposed between the plurality of snares, wherein inflating the spreader balloon moves the snares relative to the probe. The device may further include a movement element connected between the snares and the probe and configured to move the snares relative to the probe in a rearward direction opposite to the forward direction. The stop element may include a stop balloon mounted to the catheter, the stop balloon having an inflated condition in which the stop balloon defines a peripheral surface extending at least partially around a forward-to-rearward axis of the catheter and having a diameter larger than the catheter, and one or more recesses in the peripheral surface, the recesses extending across the peripheral surface in the forward and rearward directions so that when the stop balloon is in the inflated condition, the peripheral surface is engaged with the wall of the lumen and the recesses and the wall of the lumen cooperatively define the one or more passages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Various embodiments of the present invention are described herein with reference to the drawings, wherein: 
           [0017]      FIG. 1  is a side elevational view of a conventional prosthetic heart valve; 
           [0018]      FIG. 2A  is a schematic side elevational view of a prosthetic heart valve properly positioned in a native valve annulus; 
           [0019]      FIG. 2B  is a schematic side elevational view of a prosthetic heart valve that requires repositioning in the native annulus; 
           [0020]      FIG. 3A  is a schematic side elevational view of a repositioning device having a balloon; 
           [0021]      FIG. 3B  is a schematic perspective view of a balloon of a repositioning device; 
           [0022]      FIG. 4A  is a schematic side elevational view of a repositioning device having a balloon and a snare; 
           [0023]      FIG. 4B  is a schematic side elevational view of a second example of a repositioning device having a balloon and a snare; 
           [0024]      FIG. 4C  is a schematic perspective view of the balloon illustrated in  FIG. 4B ; 
           [0025]      FIG. 5  is a schematic side elevational view of a repositioning device having a balloon and multiple snares; 
           [0026]      FIG. 6A  is a schematic side elevational view of a repositioning device having a spreader balloon in the collapsed position; 
           [0027]      FIG. 6B  is a schematic side elevational view of the repositioning device of  FIG. 6A  in the expanded position; and 
           [0028]      FIG. 7  is a schematic side elevational view of a repositioning device having a movement element. 
       
    
    
       [0029]    Various embodiments of the present invention will now be described with reference to the appended drawings. It is appreciated that these drawings depict only some embodiments of the invention and are therefore not to be considered limiting of its scope. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    As used herein, the term “proximal,” when used in connection with a prosthetic heart valve, refers to the portion or end of the heart valve closest to the heart when the heart valve is implanted in a patient, whereas the term “distal,” when used in connection with a prosthetic heart valve, refers to the portion or end of the heart valve farthest from the heart when the heart valve is implanted in a patient. When used in connection with devices for delivering a prosthetic heart valve into a patient, the terms “proximal” and “distal” are to be taken as relative to the user of the delivery devices. “Proximal” is to be understood as relatively close to the user, and “distal” is to be understood as relatively farther away from the user. 
         [0031]      FIG. 1  shows a conventional collapsible prosthetic heart valve  100 . The prosthetic heart valve  100  is designed to replace the function of a native aortic valve of a patient. Examples of collapsible prosthetic heart valves are described in International Patent Application Publication No. WO/2009/042196; U.S. Pat. No. 7,018,406; and U.S. Pat. No. 7,329,278, the disclosures of all of which are hereby incorporated herein by reference. As discussed in detail below, the prosthetic heart valve has an expanded condition and a collapsed condition. Although the invention is described herein as applied to a prosthetic heart valve for replacing a native aortic valve, the invention is not so limited, and may be applied to prosthetic valves for other cardiac applications. 
         [0032]    The prosthetic heart valve  100  includes a stent or frame  102 , which may be wholly or partly formed of any biocompatible material, such as metals, synthetic polymers, or biopolymers capable of functioning as a stent. Suitable biopolymers include, but are not limited to, elastin, and mixtures or composites thereof. Suitable metals include, but are not limited to, cobalt, titanium, nickel, chromium, stainless steel, and alloys thereof, including nitinol. Suitable synthetic polymers for use as a stent include, but are not limited to, thermoplastics, such as polyolefins, polyesters, polyamides, polysulfones, acrylics, polyacrylonitriles, polyetheretherketone (PEEK), and polyaramides. The stent  102  may have an annulus section  110  and an aortic section (not shown). Each of the annulus section  110  and the aortic section of the stent  102  includes a plurality of cells  112  connected to one another around the stent. The annulus section  110  and the aortic section of the stent  102  may include one or more annular rows of cells  112  connected to one another. For instance, the annulus section  110  may have two annular rows of cells  112 . When the prosthetic heart valve  100  is in the expanded condition, each cell  112  may be substantially diamond shaped. Regardless of its shape, each cell  112  is formed by a plurality of struts  114 . For example, a cell  112  may be formed by four struts  114 . 
         [0033]    The stent  102  may include commissure points  116  connecting at least two cells  112  in the longitudinal direction of the stent  102 . The commissure points  116  may include eyelets for facilitating the suturing of a valve assembly  104  to the sent  102 . 
         [0034]    The prosthetic heart valve  100  also includes a valve assembly  104  attached inside the annulus section  110  of the stent  102 . United States Patent Application Publication No. 2008/0228264, filed Mar. 12, 2007, and United States Patent Application Publication No. 2008/0147179, filed Dec. 19, 2007, the entire disclosures of both of which are hereby incorporated herein by reference, describe suitable valve assemblies. The valve assembly  104  may be wholly or partly formed of any suitable biological material or polymer. Examples of biological materials suitable for the valve assembly  104  include, but are not limited to, porcine or bovine pericardial tissue. Examples of polymers suitable for the valve assembly  104  include, but are not limited to, polyurethane and polyester. 
         [0035]    The valve assembly  104  may include a cuff  106  disposed on the lumenal surface of annulus section  110 , on the ablumenal surface of annulus section  110 , or on both surfaces, and the cuff may cover all or part of either or both of the lumenal and ablumenal surfaces of the annulus section.  FIG. 1  shows cuff  106  disposed on the lumenal surface of annulus section  110  so as to cover part of the annulus section while leaving another part thereof uncovered. The valve assembly  104  may further include a plurality of leaflets  108  which collectively function as a one-way valve. A first edge  122  of each leaflet  108  may be attached to the cuff  106  or the stent  102  by any suitable attachment means, such as suturing, stapling, adhesives or the like. For example, the first edge  122  of each leaflet  108  may be attached to the cuff  106 , and the cuff may in turn be attached to the stent  102 . Alternatively, the first edge  122  of each leaflet  108  may be sutured to the stent  102  by passing strings or sutures through the cuff  106  of the valve assembly  104 . A second or free edge  124  of each leaflet  108  may coapt with the corresponding free edges of the other leaflets, thereby enabling the leaflets to function collectively as a one-way valve. 
         [0036]    Irrespective of the attachment means employed, the leaflets  108  may be attached to the cuff  106  or to the stent  102  along at least some struts  114  of the stent to enhance the structural integrity of the valve assembly  104 . As a consequence of this attachment, the struts  114  help support the leaflets  108  of the valve assembly  104  and may therefore reduce the strain in the leaflet-cuff junction. 
         [0037]    In operation, the embodiment of the prosthetic heart valve described above may be used to replace a native heart valve, such as the aortic valve. The prosthetic heart valve may be delivered to the desired site (e.g., near a native aortic annulus) using any suitable delivery device. Typically, during delivery, the prosthetic heart valve is disposed inside the delivery device in the collapsed condition. The delivery device may be introduced into a patient using a transfemoral, transapical, transseptal or other approach. Once the delivery device has reached the target site, the user may deploy the prosthetic heart valve. Upon deployment, the prosthetic heart valve expands, preferably into secure engagement within the native aortic annulus. When the prosthetic heart valve is properly positioned inside the heart, it works as a one-way valve, allowing blood to flow in one direction and preventing blood from flowing in the opposite direction. 
         [0038]    Problems may be encountered when implanting the prosthetic heart valve. For example, in certain procedures, collapsible valves may be implanted in a native valve annulus but not initially placed in an ideal position. If the collapsible valve has been fully deployed (e.g., unsheathed) it may be difficult to reposition the valve in the proper location. 
         [0039]    Improper placement of the valve may lead to a host of problem, such as: (1) perivalvular leakage (PV leak), (2) valve migration, (3) mitral valve impingement, (4) conduction system disruption, (5) coronary blockage, etc., all of which can have severely adverse clinical outcomes. To reduce these adverse events, devices may be used to reposition the heart valve after full deployment. 
         [0040]      FIG. 2A  illustrates a prosthetic heart valve  200  positioned within a coronary artery of a patient. Specifically, as seen in  FIG. 2A , heart valve  200  includes an annulus section  210  and an aortic section  220  in their fully-expanded condition. Annulus section  210  is disposed within the native valve annulus  290 . It is often difficult to unsheathe heart valve  200  at the appropriate location without needing to reposition the valve slightly. 
         [0041]      FIG. 2B  illustrates a prosthetic heart valve  200  that is not properly located within native valve annulus  290 , a condition that may lead to problems in operation of the valve. For example, heart valve  200  may be distorted or incapable of expanding fully resulting in a condition in which not all of the valve leaflets meet to form effective coaptation junctions. This can result in leakage or regurgitation and other inefficiencies which can reduce cardiac performance. Moreover, if the prosthetic valve  200  is not placed optimally and the valve leaflets are not coapting as intended, other long term effects, such as uneven wear of the individual leaflets, can be postulated. Thus, in such instances, heart valve  200  may require that it be shifted as indicated by arrows “A”. One method of repositioning heart valve  200  requires resheathing the heart valve and redeploying it. This method may be undesirable as it increases the time of operation and the risk of additional trauma to the vasculature during deployment. 
         [0042]    In order to avoid these problems, a valve repositioning device may be used to carefully reposition a deployed valve within the patient vasculature. The valve repositioning device may be deployed at or near the heart valve in order to reposition it. In at least some examples, the repositioning device is introduced via the aorta. Aortic techniques will be described but it should be understood that this is merely illustrative and that the valve repositioning device may be used to reposition prosthetic devices other than the prosthetic aortic valves. 
         [0043]      FIG. 3A  illustrates a valve repositioning device  300  according to a first embodiment of the present invention. The valve repositioning device  300  includes an expansible stop element  302  and a delivery catheter  350  attached to the stop element  302 . In the examples shown in  FIG. 3A , the stop element is a balloon made wholly or partly formed of but not limited to non-compliant materials such as polyethylene terephthalates, polyacrylenesulfide, and copolyesters or compliant materials such as polyvinyl chloride (PVC), polyurethanes, cross-linked low density polyethylenes [PETs],and highly irradiated linear low density polyethylene [LDPE] or semi-compliant materials such as nylon and polyamines. 
         [0044]    Prior to insertion into a patient, stop element  302  may be folded into the collapsed condition, for example, using a pleat fold or a T-fold. In the collapsed condition, the diameter of stop element  302  may be about 4 mm or less. Once the repositioning device  300  has been placed in the desired position within the patient, a fluid may be injected into the stop element  302  to expand the stop element to a suitable diameter. Specifically, catheter  350  may define a bore  360  extending forwardly and rearwardly through the catheter and a conduit  355  disposed within the bore and in fluid communication with the interior of the stop element  302  for carrying a fluid from a fluid source (not shown) to the interior of the stop element via port  308 . Inflation fluids may be a gas, such as helium or carbon dioxide, or a liquid, such as saline. 
         [0045]      FIG. 3B  illustrates one example of stop element  302  in its fully expanded condition. For the sake of clarity, catheter  350  and conduit  355  are not shown. As illustrated in  FIG. 3B  stop element  302  be a toroid or doughnut-shaped. It will be understood that stop element  302  may be formed in other shapes and other cross-sectional shapes are contemplated, including, for example, triangular, rectangular, trapezoidal, elliptical, curved, and other polygonal and non-polygonal shapes. When fully expanded, stop element  302  has a cross-sectional size that is at least equal to the cross-sectional size of the aortic sinus. This will ensure that stop element  302  fully contacts the native tissue around substantially the entirety of the sinus. Optionally, the toroid-shaped stop element  302  includes one or more passages through which a snare may be passed to maneuver an implant.  FIG. 3B  illustrates a stop element having a passage in the form of a central aperture  310 . Central aperture  310  of stop element  302  may allow additional devices, such as snares described with reference to  FIGS. 4-5 , to be deployed to reposition heart valve  200 . 
         [0046]    Stop element  302  may serve as a backstop or anchor when repositioning prosthetic heart valve  200 . Specifically, as seen in  FIG. 3A , stop element  302  may be positioned in the aorta to prevent heart valve  200  from migrating into the aorta during repositioning. 
         [0047]      FIGS. 4A and 4B  illustrate a valve repositioning device including a catheter coupled to a stop element and a snare. The devices are used to reposition heart valves within the aortic sinus. 
         [0048]    As seen in  FIG. 4A , snare  410  may be introduced through central aperture  310  of stop element  302 . With this configuration, stop element  302  may be securely anchored against the walls of the native valve annulus to prevent heart valve  200  from traveling into the aorta should the snare  410  pull the heart valve too far upward. Snare  410  may be formed as a wire (e.g., a guidewire) having an engagement feature  420  for coupling to a portion of the prosthetic heart valve  200 . Engagement feature  420  may include any type of coupling mechanism such as a hook, clip or tab for coupling to a portion of the stent or prosthetic heart valve to reposition it. In at least some examples, snare  410  includes an engagement feature  420  in the shape of a circle to couple to a tab on the stent. Snare  410  may be used to reposition heart valve  200  by pulling the heart valve while stop element  302  prevents the heart valve  200  from going too far into the aorta. 
         [0049]    Snare  410  may be wholly or partly formed of any biocompatible material, such as metals, synthetic polymers, or biopolymers. Suitable biopolymers include, but are not limited to, elastin, and mixtures or composites thereof. Suitable metals include, but are not limited to, cobalt, titanium, nickel, chromium, stainless steel, and alloys thereof, including nitinol. Suitable synthetic polymers for use as a snare include, but are not limited to, thermoplastics, such as polyolefins, polyesters, polyamides, polysulfones, acrylics, polyacrylonitriles, polyetheretherketone (PEEK), and polyaramides. 
         [0050]    The following will describe the use of a repositioning device for properly positioning an implant, in this case a prosthetic heart valve. As an initial step, stop element  302  of repositioning device  300  may first be inserted into the patient in the collapsed condition and advanced to the desired site for valve repositioning at location offset from the implant. For example, repositioning device  300  may be inserted into the patient&#39;s vasculature and advanced near the aorta and the site of the native aortic valve. If the repositioning device  300  includes echogenic materials, it may be guided to the appropriate position using the assistance of three-dimensional echocaradiography to visualize the repositioning device  300  within the patient. 
         [0051]    Once repositioning device  300  has reached the desired site, stop element  302  may be inflated to assume an expanded shape by introducing a fluid through fluid conduit  355 . With stop element  302  in its expanded condition, central aperture  310  is formed through which snares  410  may be introduced. Snares  410  may be passed from the catheter  350  through a passage such as a central aperture and engagement features  420  may mate with a portion of the implant. Snares  410  may then be actuated as desired to reposition heart valve  200  into its optimum or desired position. Upon repositioning of heart valve  200 , snares  410  may be detached from the heart valve and pulled back through central aperture  310  and into catheter  350 . Stop element  302  may be collapsed by removing the fluid therefrom and the repositioning device  300  may be removed from the patient&#39;s body. While the operation of the repositioning device  300  of  FIG. 4A  has been described, it will be understood that other examples described may be implemented in a similar manner. 
         [0052]      FIGS. 4B and 4C  illustrate a second example of a stop element and snare assembly. As seen in  FIG. 4B , with stop element  302  in position at the aorta, a snare  410  may be passed alongside stop element  302  to reposition heart valve  200 . Instead of a passage in the form of a central aperture, stop element  302  may include one or more concave portions  320  on the periphery. One exemplary stop element  302  having two concave portions  320  is shown in  FIG. 4C . Concave portions  320  form passages between the stop element and the wall of the lumen through which snares may be advanced. It will be understood that stop element  302  and snare  410  may be combined into a single repositioning device or may be formed, introduced and/or actuated separately. 
         [0053]      FIG. 5  illustrates a valve repositioning device  500  having an expandable stop element  302  attached to a delivery catheter  350  and multiple snares  410  passing through the central aperture  310  of stop element  302 . By employing multiple snares  410 , the position of valve  200  may be uniformly adjusted and uneven repositioning may be avoided. Any number of snares  410  may be used at necessary. In at least some examples, one, two, three, four, five, six, seven or eight snares  410  may be used to reposition heart valve  200 . 
         [0054]    As seen in  FIG. 5 , snares  410  may be evenly distributed to attach to portions of stent  220 . In at least some examples, even distribution of snares  410  may be accomplished by evenly distributing snares  410  about the circumference of stent  220 . For example, two snares  410  may be diametrically opposed on stent  220 . Three snares  410  may likewise be attached  120  degrees apart from each other about stent  220  to accomplish even repositioning of heart valve  200 . Snares  410  may be actuated independently such that the user may pull a single snare  410  to reposition an end of heart valve  200 . In at least some other examples, snares  410  may be actuated together. Snares  410  may be connected to an elongated probe  510  and joined to a single node  520 . Pulling or actuating elongated probe  510  may serve to actuate all snares  410  at the same time. Snares  410  may be resilient and outwardly biased so that when deployed through stop element  302 , snares spread outwardly, away from one another in lateral directions transverse to a forward direction. 
         [0055]    All or part of the repositioning device, such as the stop element, delivery catheter and/or snares, may be made of one or more echogenic materials to enable these structures to be more easily visualized using three-dimensional echocardiography while the device is in use in a patient. This allows the physician or surgeon to more easily maneuver, monitor and retract the device without any injury to the patient. 
         [0056]      FIG. 6A  illustrates another embodiment of a repositioning device  300  in a collapsed condition. Instead of biasing the snares, a spreader balloon may be used to manipulate the snares. As shown in this figure, repositioning device  300  is similar to that describe above, but includes a spreader balloon  610  disposed between the snares  410 . Elongated probe  510  may further define a channel  620  in fluid communication with spreader balloon  610  and configured to inflate it. Channel  610  may run along the length of bore  360  of catheter  350 . 
         [0057]      FIG. 6B  illustrates the repositioning device  300  of  FIG. 6A  in its expanded condition. As seen in  FIG. 6B , as spreader balloon  610  begins to inflate, it begins to take on a less-elongate expanded configuration. Specifically, spreader balloon  610  widens and shortens to assume its expanded configuration and snares  410  begin to spread outwardly, away from one another in lateral directions transverse to a forward direction. Thus, instead of having biased snares, snares  410  may be manipulated using a spreader balloon  610 . 
         [0058]    In operation, stop element  302  may be introduced into a vessel, such as the aorta, in the deflated configuration. Stop element  302  may be inflated using a gas or fluid through conduit  360  and snares  410  may be advanced through central aperture  310  of the stop element. Spreader balloon  610  may then be inflated to outwardly push snares  410  until engagement feature  420  of snare  410  couple to a portion of an implant, such as a heart valve. The implant may be repositioned as needed by pulling on the elongated probe. Once the implant has been properly positioned, spreader balloon  610  may be deflated to decouple the engagement features of the snares from the implant. Stop element  302  may then be deflated and the catheter, stop element and snares retrieved and removed from the patient&#39;s body. 
         [0059]      FIG. 7  illustrates another embodiment of a repositioning device  300  in a deployed condition. In this embodiment, a movement element  650  is connected between snares  410  and elongated probe  510  and configured to move the snares relative to the probe in a forward direction toward the implant and a rearward direction opposite the forward direction. Movement element  650  may be actuated by a button on handle at the proximal end of the catheter (not shown). The movement element may include an inflatable element or any other movement mechanism. Operation of this variation is similar to that described with reference to  FIGS. 6A and 6B . However, instead of retracting the elongated probe, the user may actuate the movement element  640  causing the snares to move in the rearward direction toward the stop element to reposition the implant. It will be understood that this configuration may be modified in any of the methods describe above. For example, a configuration may be made that utilizes both a movement element and a spreader balloon. Additionally, the shape and size of stop element may be modified as necessary. 
         [0060]    It will also be noted that while the inventions herein are predominately described in connection with the replacement of a tricuspid valve, the inventions are equally applicable to the replacement of other valves, including a bicuspid valve, such as the mitral valve. Moreover, the snares could have different shapes, or engagement features depending on the devices being repositioned. 
         [0061]    Moreover, although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. 
         [0062]    It will be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims. It will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments.