Abstract:
This invention relates to the design and function of a retrieval device for a prosthetic heart valve for re-positioning or removal of a previously implanted valve prosthesis from a beating heart without extracorporeal circulation using a transcatheter retrieval system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 14/154,816, filed Jan. 14, 2014, which claims priority to and the benefit of U.S. Provisional Application No. 61/808,458, filed Apr. 4, 2013, the contents of each of which are incorporated by reference herein in their entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a novel device and method for retrieval of a transcatheter heart valve replacement or for capture and repositioning of a deployed transcatheter heart valve replacement. 
         [0004]    2. Background of the Invention 
         [0005]    Valvular heart disease and specifically aortic and mitral valve disease is a significant health issue in the US. Annually approximately 90,000 valve replacements are conducted in the US. Traditional valve replacement surgery, the orthotopic replacement of a heart valve, is an “open heart” surgical procedure. Briefly, the procedure necessitates a surgical opening of the thorax, initiation of extra-corporeal circulation with a heart-lung machine, stopping and opening the heart, excision and replacement of the diseased valve, and re-starting of the heart. While valve replacement surgery typically carries a 1-4% mortality risk in otherwise healthy persons, a significantly higher morbidity is associated to the procedure largely due to the necessity for extra-corporeal circulation. Further, open heart surgery is often poorly tolerated in elderly patients. 
         [0006]    Thus if the extra-corporeal component of the procedure could be eliminated, morbidities and cost of valve replacement therapies would be significantly reduced. 
         [0007]    While replacement of the aortic valve in a transcatheter manner is the subject of intense investigation, lesser attention has been focused on the mitral valve. This is in part reflective of the greater level of complexity associated to the native mitral valve apparatus and thus a greater level of difficulty with regards to inserting and anchoring the replacement prosthesis. 
         [0008]    Several designs for catheter-deployed (transcatheter) aortic valve replacement are under various stages of development. The Edwards SAPIEN® transcatheter heart valve is currently undergoing clinical trial in patients with calcific aortic valve disease who are considered high-risk for conventional open-heart valve surgery. This valve is deployable via a retrograde transarterial (transfemoral) approach or an antegrade transapical (transventricular) approach. A key aspect of the Edwards SAPIEN® and other transcatheter aortic valve replacement designs is their dependence on lateral fixation (e.g. tines) that engages the valve tissues as the primary anchoring mechanism. Such a design basically relies on circumferential friction around the valve housing or stent to prevent dislodgement during the cardiac cycle. This anchoring mechanism is facilitated by, and may somewhat depend on, a calcified aortic valve annulus. This design also requires that the valve housing or stent have a certain degree of rigidity. 
         [0009]    At least one transcatheter mitral valve design is currently in development. The Endovalve uses a folding tripod-like design that delivers a tri-leaflet bioprosthetic valve. It is designed to be deployed from a minimally invasive transatrial approach, and could eventually be adapted to a transvenous atrial septotomy delivery. This design uses “proprietary gripping features” designed to engage the valve annulus and leaflets tissues. Thus the anchoring mechanism of this device is essentially equivalent to that used by transcatheter aortic valve replacement designs. 
         [0010]    Various problems continue to exist in this field, including problems with how to retrieve a collapsible heart valve prosthetic from the native valve once the prosthetic has reached the end of its useful life. For example, a prosthetic heart valve may be delivered and secured percutaneously or intravenously using a catheter and endoscope or similar device, but the process of disengaging anchoring mechanisms and collapsing the prosthetic for retrieval is often more difficult to accomplish than is the delivery. Accordingly, there is a need for an improved device and method for retrieval when such valves need to be replaced. 
       SUMMARY 
       [0011]    The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later. 
         [0012]    In one embodiment, there is provided a prosthetic heart valve retrieval and repositioning device, comprising: a dilator sheath, said dilator sheath having a lumen therethrough and a dilator base mounted on a proximal side of said dilator sheath, said dilator base having a sheath lock for operatively engaging the dilator sheath for opening and closing the lumen of said dilator sheath, said dilator base having a slidably removable inner catheter disposed within the lumen, said inner catheter having a tapered tip at a distal end and an inner catheter base at a proximal end wherein said inner catheter base is adjacent and proximal to the dilator base, said dilator base having a guide rod aperture for engaging a guide rod that is connected to a guide rod handle mount that is attached to a handle apparatus, said inner catheter base having a traveller strap affixed on a proximal side and said traveller strap extending proximally to engage a tensioning unit on the handle apparatus, said handle apparatus having an actuator and a spring operatively connected to the traveller strap, wherein when the actuator is engaged the traveller strap is pulled proximally through the tensioning unit and the inner catheter base slides along guide rod towards the handle apparatus. 
         [0013]    In another preferred embodiment, there is provided a prosthetic heart valve retrieval and removal device, comprising: a dilator sheath having a lumen therethrough and a dilator base mounted on a proximal side of said dilator sheath, said dilator base having a sheath lock for operatively engaging the dilator sheath for opening and closing the lumen of said dilator sheath, said dilator base having a slidably removable intermediate beveled catheter disposed within the lumen, said intermediate beveled catheter having an intermediate base mounted on a proximal side of said intermediate beveled catheter, said intermediate beveled catheter having a lumen therethrough and having inner catheter having a tapered tip at a distal end disposed within the intermediate beveled catheter, said inner catheter having an inner catheter base mounted on a proximal side of said inner catheter, wherein said inner catheter base is adjacent and proximal to the intermediate base and said intermediate base is adjacent and proximal to the dilator base, said dilator base having a guide rod aperture for engaging a guide rod that is connected to a guide rod handle mount that is attached to a handle apparatus, said inner catheter base having a traveller strap affixed on a proximal side and said traveller strap extending proximally to engage a tensioning unit on the handle apparatus, said handle apparatus having an actuator and a spring, wherein when the actuator is engaged the traveller strap is pulled proximally through the tensioning unit and the inner catheter base slides along guide rod towards the handle apparatus. 
         [0014]    In another preferred embodiment, there is provided a prosthetic heart valve retrieval device wherein the tapered tip is bullet-shaped, cone-shaped, hooded, or otherwise shaped to guide the valve tether into the lumen of the dilator sheath. 
         [0015]    In another preferred embodiment, there is provided wherein the dilator has a radio band affixed thereto. 
         [0016]    In another preferred embodiment, there is provided a method of using the retrieval device for capturing a tethered expandable prosthetic heart valve to retrieve and re-position said valve, comprising the steps of: (i) inserting said retrieval and repositioning device into a body cavity of a patient containing a tethered and expandable prosthetic heart valve into a patient, (ii) capturing and retracting the tether into the retrieval device, and (iii) repositioning the tethered expandable prosthetic heart valve. 
         [0017]    In another preferred embodiment, the method of retrieving and re-positioning also includes the step of (iv) removing the tethered and expandable heart valve from the patient by collapsing the expandable prosthetic heart valve apparatus into the dilator sheath catheter and retracting the dilator sheath. 
         [0018]    In another preferred embodiment, there is provided a method of using the retrieval device for capturing a tethered expandable prosthetic heart valve to retrieve and remove said valve, comprising the steps of: (i) inserting said retrieval and removal device into a body cavity of a patient containing a tethered and expandable prosthetic heart valve into a patient, and (ii) capturing and retracting the tethered expandable prosthetic heart valve into the retrieval and removal device. 
         [0019]    In another preferred embodiment, there is provided wherein the step of inserting the retrieval device by directly accessing the heart through the intercostal space, or using an apical approach to enter a heart ventricle. 
         [0020]    In another preferred embodiment, there is provided wherein the step of inserting the retrieval device by directly accessing the heart through a thoracotomy, sternotomy, or minimally-invasive thoracic, thorascopic, or trans-diaphragmatic approach to enter the left ventricle. 
         [0021]    To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The attached figures provide enabling and non-limiting example of certain features of the present invention. The figures are not intended to be limiting in any way to the description that is provided in the text. 
           [0023]      FIG. 1  is a side perspective view of one embodiment of a handle and support/pusher rod apparatus for the prosthetic valve retrieval system provided herein. 
           [0024]      FIG. 2  is a side perspective view of a double-sleeved dilator &amp; catheter assembly with tensioning/traveller strap and two-part retaining collar and gated bore collar. 
           [0025]      FIG. 3  is a side perspective view of a partially disassembled double-sleeved dilator &amp; catheter assembly with outer sheath having distance/location markings and gated bore collar and the tapered inner catheter disposed within the outer sheath which has tensioning/traveller strap and retaining collar operatively associated therewith. 
           [0026]      FIG. 4  is a side detailed view of two-part retaining collar and gated bore collar showing how support rod fits into the key slot of the retaining collar and the double-sleeved retrieval and repositioning catheter extends from gated bore collar. 
           [0027]      FIG. 5  is a side detailed view of the handle and actuator with support/pusher rod and traveller strap disposed within the strap tensioning jaw. 
           [0028]      FIG. 6  is a side perspective view of the tapered conical catheter tip having capture wire extending therethrough and capturing the tether of a deployed prosthetic valve in a demonstration model of a body cavity such as a ventricle. 
           [0029]      FIG. 7  is a side perspective view of the double-sleeved retrieval and repositioning catheter that has been partially advanced into the ventricle or cavity of the demonstration model of a ventricle towards the valve/device to be retrieved while the tether slack is reeled in or gathered. 
           [0030]      FIG. 8  is a side perspective view of the double-sleeved retrieval and repositioning catheter that has been advanced into the ventricle or cavity of a demonstration model of a ventricle towards the valve/device to be retrieved while the tether slack is reeled in or gathered. 
           [0031]      FIG. 9  is a side perspective view of the double-sleeved retrieval and repositioning catheter that has been advanced into the ventricle or cavity of the demonstration model of a ventricle towards the valve/device to be retrieved while the tether slack is reeled in or gathered and the tapered tip engages the strut bundle of the valve. 
           [0032]      FIG. 10  is a perspective view of the retaining collar and gated-bore collar with the captured tether exiting the proximal end of the stylet and tether screw in an open position prior to adjustment to secure the tether. 
           [0033]      FIG. 11  is a perspective view of the retaining collar and gated-bore collar with the tether screw fully adjusted into a locked or closed position for securing the tether. 
           [0034]      FIG. 12  is a perspective view of the support rod/pusher rod after the tether has been secured and shows distance markers. 
           [0035]      FIG. 13  is a perspective view of the double-sleeved catheter that has been advanced through the ventricle or cavity of the demonstration model of a ventricle beyond the location of the valve annulus of the demonstration model.  FIG. 13  shows the tapered tip of the inner catheter engaging the strut bundle of the valve and expelling the deployed valve from the annulus into an atrial location of the demonstration model. 
           [0036]      FIG. 14  is a perspective detail view of the double-sleeved retrieval and repositioning catheter that has been advanced through the ventricle or cavity of the demonstration model of a ventricle beyond the location of the valve annulus of the demonstration model.  FIG. 14  shows the tapered tip of the inner catheter engaging the strut bundle of the valve and expelling the deployed valve from the annulus into an atrium location of the demonstration model. 
           [0037]      FIG. 15  is a detail view of the retaining collar with the tether screw fully adjusted into a locked or closed position for securing the tether and the marker on the support rod illustrating the initial pre-retrieval distance that actuating the traveller strap has accomplished during the initial capture and securing of the valve to be retrieved. 
           [0038]      FIG. 16  is a detail view of the traveller strap entering the tensioning jaw. 
           [0039]      FIG. 17  is a detail view of the misaligned valve prior to being re-positioned into a better alignment, e.g. A2 conforming segment of the atrial cuff on the valve aligned with A2 location of native annulus. 
           [0040]      FIG. 18  is a detail view of the valve after re-positioning and redeployment into the valve annulus of the demonstration model framework. 
           [0041]      FIG. 19  is a side view of the retrieved and re-positioned valve mounted in the tethered valve deployment demonstration model, e.g. left ventricle, right ventricle, body cavity, etc. and shows the struts, strut bundle, and tether extending across the cavity and out through the body wall access port. 
           [0042]      FIG. 20  is a side view of a three-part triple-sheathed retrieval and removal catheter having a flared outer dilator sheath with an intermediate beveled catheter disposed within and an inner catheter having a tapered tip disposed within the intermediate beveled catheter. 
           [0043]      FIG. 21  is a detail view of the two outermost catheters of the triple-sheathed retrieval and removal catheter and shows a flared outer dilator sheath with an intermediate beveled catheter disposed within. 
           [0044]      FIG. 22  is a detail view of the assembled retrieval and removal catheter apparatus and shows support rod extending from the retaining collar across a collar stabilizer to the gated bore collar, traveller strap attached to the retaining collar and sliding gate mounted on the gated-bore collar, with the triple-sheathed catheter attached to a distal end of the gated-bore collar and stylet and inner catheter extending through the axis of the entire apparatus. 
           [0045]      FIG. 23  is a perspective view of the triple-sheathed catheter that has been advanced through the ventricle or cavity of the demonstration model of a ventricle beyond the location of the valve annulus of the demonstration model.  FIG. 23  shows the tapered tip of the inner catheter engaging the strut bundle of the valve just prior to expelling the deployed valve from the annulus into an atrial location of the demonstration model. 
           [0046]      FIG. 24  is a perspective view of the triple-sheathed removal catheter and shows the valve partially withdrawn in the flared outer dilator sheath after the inner catheter has taken control of the strut bundle using the tapered tip and the intermediate beveled catheter has controllably collapsed and compressed the valve struts. 
           [0047]      FIG. 25  is a side perspective view of the valve being further drawn into the protective flared end of the flared outer dilator sheath.  FIG. 25  also shows the catheter extending across the lumen of the ventricle of the model with the gated-bore collar outside of the body wall access port (proximal side) and the valve being removed from inside an atrial space of the demonstration model. 
           [0048]      FIG. 26  is a side perspective view of the valve being further drawn into the protective flared end of the flared outer dilator sheath.  FIG. 26  also shows radio-marker band at the tip of the outer catheter. 
           [0049]      FIG. 27  is a side perspective view and shows the valve entirely removed and withdrawn into the outer catheter. 
       
    
    
     DETAILED DESCRIPTION 
       [0050]    Various aspects are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. 
       Functions of the Retrieval System 
       [0051]    The present invention provides in one embodiment a retrieval system for a previously deployed prosthetic heart valve wherein a valve tether is attached to the valve or to a collapsible stent containing the valve and the apparatus provided herein provides a method for capturing the tether of said valve, dislodging the deployed valve from the valve annulus, and then either re-positioning the valve and redeploying it, or removing the valve entirely. 
         [0052]    The invention also allows for the capture of one or more retrieval tethers by a catheter-based extraction device, and for the re-positioning or removing the entire deployed valve apparatus via the retrieval device using an outpatient catheterization procedure without requiring major surgery. 
       Access &amp; Deployment of the Retrieval Device 
       [0053]    In one aspect of the retrieval, the catheter retrieval system accesses the heart and pericardial space by intercostal delivery. In this case, the pusher unit and catheters may be short, e.g. 12-38 cm. 
         [0054]    In another retrieval approach, the catheter retrieval system retrieves the prosthetic heart valve using either an antegrade or retrograde approach using a flexible catheter system, and without requiring the rigid tube system commonly used. In another embodiment, the catheter system accesses the heart via a trans-septal approach. In either case, where a long distance must be travelled the pusher unit and associated catheters and equipment is contemplated as being within the range of 60-150 cm long. 
         [0055]    Prosthetic Valve Devices 
         [0056]    The prosthetic heart valve contemplated for retrieval using the retrieval device comprises a self-expanding tubular stent having a cuff at one end and tether loops for attaching tether(s) at the other end, and disposed within the tubular stent is a leaflet assembly that contains the valve leaflets, the valve leaflets being formed from stabilized tissue or other suitable biological or synthetic material. In one embodiment, the leaflet assembly comprises a wire form where a formed wire structure is used in conjunction with stabilized tissue to create a leaflet support structure which can have anywhere from 1, 2, 3 or 4 leaflets, or valve cusps disposed therein. In another embodiment, the leaflet assembly is wireless and uses only the stabilized tissue and stent body to provide the leaflet support structure, without using wire, and which can also have anywhere from 1, 2, 3 or 4 leaflets, or valve cusps disposed therein. 
         [0057]    The tether anchors the valve to an anchoring location within the ventricle. Preferably, the location is the apex of the heart and uses an epicardial attachment pad. However, other tether attachment locations may be used in the deployment of the valve and also therefore, for the retrieval. 
         [0058]    The cuff of the valve functions to counter the forces that act to displace the prosthesis toward/into the ventricle (i.e., atrial pressure and flow-generated shear stress) during ventricular filling. Accordingly, the stent containing the valve is positioned and pulled between the ventricular tether and the atrial cuff. 
       Cuff Structure 
       [0059]    The cuff is a substantially flat plate that projects beyond the diameter of the tubular stent to form a rim or border. As used herein, the term cuff, flange, collar, bonnet, apron, or skirting are considered to be functionally equivalent. When the tubular stent is pulled through the mitral valve aperture, the mitral annulus, by the tether loops in the direction of the left ventricle, the cuff acts as a collar to stop the tubular stent from traveling any further through the mitral valve aperture. The entire prosthetic valve is held by longitudinal forces between the cuff which is seated in the left atrium and mitral annulus, and the ventricular tethers attached to the left ventricle. 
         [0060]    The cuff is formed from a stiff, flexible shape-memory material such as the nickel-titanium alloy material Nitinol® wire that is covered by stabilized tissue or other suitable biocompatible or synthetic material. In one embodiment, the cuff wire form is constructed from independent loops of wire that create lobes or segments extending axially around the circumference of the bend or seam where the cuff transitions to the tubular stent (in an integral cuff) or where the cuff is attached to the stent (where they are separate, but joined components). 
         [0061]    Once covered by stabilized tissue or material, the loops provide the cuff with the ability to travel up and down, to articulate, along the longitudinal axis that runs through the center of the tubular stent. In other words, the individual spindles or loops can independently move up and down, and can spring back to their original position due to the relative stiffness of the wire. The tissue or material that covers the cuff wire has a certain modulus of elasticity such that, when attached to the wire of the cuff, such tissue or material allows the wire spindles to move. 
         [0062]    The cuff counteracts the longitudinal ventricular pressure during systole against the prosthesis in the direction of the left ventricle to keep the valve from being displaced or slipping into the ventricle. The tether(s) counteracts this force and is used to maintain the valve position and withstand the ventricular force during ventricular contraction or systole. Accordingly, the entire valve must be positioned in a proper position and cannot be radially misplaced during the deployment process. After a period of time, changes in the geometry of the heart and/or fibrous adhesion between prosthesis and surrounding cardiac tissues may assist or replace the function of the ventricular tethers in resisting longitudinal forces on the valve prosthesis during ventricular contraction, so the initial deployment must be accurate. 
       Stent Structure 
       [0063]    Preferably, superelastic metal wire, such as Nitinol® wire, is also used for the stent, for the inner wire-based leaflet assembly that is disposed within the stent, and for the cuff wire form. Such stents are available from any number of commercial manufacturers, such as Pulse Systems. Laser cut stents are preferably made from Nickel-Titanium (Nitinol®), but also without limitation made from stainless steel, cobalt chromium, titanium, and other functionally equivalent metals and alloys, or Pulse Systems braided stent that is shape-set by heat treating on a fixture or mandrel. 
         [0064]    One key aspect of the stent design is that it be compressible and when released have the stated property that it return to its original (uncompressed) shape. This requirement limits the potential material selections to metals and plastics that have shape memory properties. With regards to metals, Nitinol® has been found to be especially useful since it can be processed to be austenitic, martensitic or super elastic. Martensitic and super elastic alloys can be processed to demonstrate the required compression features. 
       Laser Cut Stent 
       [0065]    One possible construction of the stent envisions the laser cutting of a thin, isodiametric Nitinol® tube. The laser cuts form regular cutouts in the thin Nitinol tube. Secondarily the tube is placed on a mold of the desired shape, heated to the martensitic temperature and quenched. The treatment of the stent in this manner will form a stent or stent/cuff that has shape memory properties and will readily revert to the memory shape at the calibrated temperature. 
       Leaflet and Inner Wireform 
       [0066]    The valve leaflets are held by, or within, a leaflet assembly. In one preferred embodiment of the invention, the leaflet assembly comprises a leaflet wire support structure to which the leaflets are attached and the entire leaflet assembly is housed within the stent body. In this embodiment, the assembly is constructed of wire and stabilized tissue to form a suitable platform for attaching the leaflets. In this aspect, the wire and stabilized tissue allow for the leaflet structure to be compressed when the prosthetic valve is compressed within the deployment catheter, and to spring open into the proper functional shape when the prosthetic valve is opened during deployment. In this embodiment, the leaflet assembly may optionally be attached to and housed within a separate cylindrical liner made of stabilized tissue or material, and the liner is then attached to line the interior of the stent body. 
         [0067]    In this embodiment, the leaflet wire support structure is constructed to have a collapsible/expandable geometry. In a preferred embodiment, the structure is a single piece of wire. The wireform is, in one embodiment, constructed from a shape memory alloy such as Nitinol®. The structure may optionally be made of a plurality of wires, including between 2 to 10 wires. Further, the geometry of the wire form is without limitation, and may optionally be a series of parabolic inverted collapsible arches to mimic the saddle-like shape of the native annulus when the leaflets are attached. Alternatively, it may optionally be constructed as collapsible concentric rings, or other similar geometric forms that are able to collapse or compress, then expand back to its functional shape. In certain preferred embodiments, there may be 2, 3 or 4 arches. In another embodiment, closed circular or ellipsoid structure designs are contemplated. In another embodiment, the wire form may be an umbrella-type structure, or other similar unfold-and-lock-open designs. A further preferred embodiment utilizes super elastic Nitinol® wire approximately 0.015″ in diameter. In this embodiment, the wire is wound around a shaping fixture in such a manner that 2-3 commissural posts are formed. The fixture containing the wrapped wire is placed in a muffle furnace at a pre-determined temperature to set the shape of the wire form and to impart it&#39;s super elastic properties. Secondarily, the loose ends of the wireform are joined with a stainless steel or Nitinol tube and crimped to form a continuous shape. In another preferred embodiment, the commissural posts of the wireform are adjoined at their tips by a circular connecting ring, or halo, whose purpose is to minimize inward deflection of the post(s). 
       Tether 
       [0068]    The tether(s) is attached to the prosthetic heart valve and extend to one or more tissue anchor locations within the heart. In one preferred embodiment, the tether(s) extend downward through the left ventricle, exiting the left ventricle at the apex of the heart to be fastened on the epicardial surface outside of the heart. In another preferred embodiment, the tether is optionally anchored to other tissue locations depending on the particular application of the prosthetic heart valve, such as one or both papillary muscles, septum, and/or ventricular wall. 
         [0069]    The tether is made from surgical-grade materials such as biocompatible polymer suture material. Examples of such material include without limitation: ultra high molecular weight polyethylene (UHWPE); 2-0 exPFTE (polytetrafluoroethylene); or 2-0 polypropylene. 
       DESCRIPTION OF THE FIGURES 
       [0070]    Referring now to the FIGURES,  FIGS. 1 and 2  shows one embodiment of a retrieval and repositioning apparatus.  FIG. 1  shows handle  110  and support/pusher rod  116  apparatus for the prosthetic valve retrieval system provided herein. The handle  110  operates with actuator  112  and spring  114  in concert with support rod  116  and tensioning strap  122  to provide a reciprocal motion responsive to the operation of the actuator  112 . The support rod  116  is fitted in key slot  132  of retaining collar  126 . The traveller strap  122  is loaded into tensioning jaw  118  and upon actuating the handle  112  divides the retaining collar  126  from the gated-bore collar  128 . Using tether screw  134  on retaining collar  126  to secure a tether from the valve to be retrieved, the reciprocal motion of the strap  122  and the rod  116  operate to pull the tether.  FIG. 2  shows detail of a double-sleeved dilator &amp; catheter assembly  120  for retrieval and repositioning with outer dilator sheath  138  having inner catheter disposed therein. Tapered tip  144  is used to abut strut bundle (not shown) secure the deployed tether. Stylet  124  has a lumen therethrough for accepting the tether and locks into retaining collar  126 . Gated-bore collar  128  has sliding gate  130  for closing off communication with the ventricle to avoid blood loss. Blind distance markers  146  are labelled on the pusher rod to provide the operator with the relative distance that the pusher rod has been advanced. Since the procedure is a catheter-based, non-surgical procedure, the valve is deployed into the patient&#39;s heart using only radiographic visualization. Thus, the blind distance markers avoid advancing the pusher rod  116  too far. 
         [0071]      FIG. 3  shows a partially disassembled double-sleeved dilator &amp; catheter assembly  120  with outer sheath  138  having distance/location markings  146  and gated bore collar  128  and the tapered inner catheter  142  disposed within the outer sheath  138  which has tensioning/traveller strap  122  and retaining collar  126  operatively associated therewith.  FIG. 3  also shows removable stylet  124 , tether screw  134  and gasket  142  on retaining collar/inner catheter base  126 .  FIG. 3  shows tapered tip  156  at the distal end of inner catheter  140 .  FIG. 3  shows sliding gate  130  on the gated-bore collar/dilator base  128  and radio band  158  at the distal end of dilator sheath  138 . 
         [0072]      FIG. 4  shows a two-part retaining collar  126  and gated bore collar  128  showing how support rod  116  fits into the key slot  132  of the retaining collar  126  and the double-sleeved retrieval and repositioning catheter  120  extends from gated bore collar  128 .  FIG. 4  also shows tether screw  134  on retaining collar for securing the captured tether, as well as rod screw  136  located on the gated-bore collar  128  for securing the position of the rod  116  within the gated-bore collar  128 . Stylet  124 , distance marker  146  and sliding gate  130  are also shown. 
         [0073]      FIG. 5  shows the handle  110  and actuator  112  with support/pusher rod  116  and traveller strap  122  disposed within the strap tensioning jaw  118 . Operating the actuator  112  pulls the strap  122  into the tensioning jaw  118  towards the handle  110 . 
         [0074]      FIG. 6  shows an over-the-wire catheter-based equipment delivery technique and specifically shows the tapered conical catheter tip  156  having capture wire  148  extending therethrough and capturing the tether  150  of a deployed prosthetic valve in a demonstration model  166  of a body cavity such as a ventricle. Demonstration model includes simulated body wall access port  154  anatomically spaced from simulated annulus  170  and shows in cross-section how the retrieval device works in the context of a body cavity. 
         [0075]      FIG. 7  shows the double-sleeved retrieval and repositioning catheter  120  that has been partially advanced through the body wall access port  154  and into the ventricle or cavity of the demonstration model  166  of a ventricle towards the valve/device  168  to be retrieved while the tether  150  slack is reeled in or gathered. The dilator outer sheath  138  of catheter  120  establishes a conduit for delivery of the retrieval and repositioning inner catheter  140  (not shown). Sliding gate  130  prevents blood loss down the catheter assembly during cavity access. 
         [0076]      FIGS. 8 and 9  show the double-sleeved retrieval and repositioning catheter  120  that has been advanced into the ventricle or cavity of a demonstration model  166  of a ventricle towards the valve/device  168  to be retrieved while the tether  150  slack is reeled in or gathered.  FIG. 8  specifically shows how tapered tip  156  is advanced until it abuts the strut bundle  152 . The positioning is used to control the release of the deployed valve  168  from the annulus  170 . 
         [0077]      FIG. 10  shows the retaining collar  126  and gated-bore collar  128  with the captured tether  150  exiting the proximal end of the stylet  124  and tether screw  134  in an open position prior to adjustment to secure the tether  150 .  FIG. 10  also shows rod  116  disposed with key slot/guide rod aperture  132  and traveller strap  122  extending parallel to the rod towards the handle  110  (not shown). Distance marker  146  is shown on rod  116 . Sliding gate  130  is also shown on dilator base/gated-bore collar  128 . Collar luer  164  is shown and provides a port for adding saline and/or removing blood or fluids. 
         [0078]      FIG. 11  shows the retaining collar  126  and gated-bore collar  128  with the tether screw  134  fully adjusted into a locked or closed position for securing the tether  150 . Sliding gate  130  is also shown on dilator base/gated-bore collar  128 . 
         [0079]      FIG. 12  shows the support rod/pusher rod  116  after the tether  150  exiting stylet  124  has been secured and shows distance markers  146 . Tensioning strap/traveller strap  122  is shown parallel to rod  116 . 
         [0080]      FIG. 13  shows the double-sleeved catheter  120  that has been advanced through the ventricle or cavity of the demonstration model  166  of a ventricle beyond the location of the valve annulus of the demonstration model.  FIG. 13  shows the tapered tip  156  of the inner catheter  140  engaging the strut bundle  152  of the valve and expelling the deployed valve  168  from the annulus  170  into an atrial location  172  of the demonstration model  166 . 
         [0081]      FIG. 14  shows the double-sleeved retrieval and repositioning catheter  120  that has been advanced through the annulus  170  of the ventricle or cavity of the demonstration model  166  of a ventricle beyond the location of the valve annulus  170  of the demonstration model.  FIG. 14  shows the tapered tip  156  of the inner catheter  142  engaging the strut bundle  152  of the valve  168  and expelling the deployed valve  168  from the annulus  170  into an atrial space  172  of the demonstration model  166 . 
         [0082]      FIG. 15  shows the retaining collar  126  with the tether screw  134  fully adjusted into a locked or closed position for securing the tether  150 , seen exiting the stylet  124 . Marker  146  on the support rod  116  illustrates the initial pre-retrieval distance that actuating the traveller strap  122  has accomplished during the initial capture and securing of the valve to be retrieved. Gasket  142  and key slot/rod aperture  132  are shown on inner catheter base  126 . 
         [0083]      FIG. 16  shows the traveller strap  122  entering the tensioning jaw  118 . Support rod  116  and handle  110  are shown mounted with tensioning jaw  118 . 
         [0084]      FIG. 17  shows the misaligned valve  168  prior to being re-positioned into a better alignment under control of the dilator assembly  120 , e.g. A2 conforming segment of the atrial cuff on the valve aligned with A2 location of native annulus. 
         [0085]      FIG. 18  shows the valve  168  after re-positioning and redeployment into the valve annulus of the demonstration model framework  166  while under control of the dilator assembly  120 . 
         [0086]      FIG. 19  shows the retrieved and re-positioned valve  168  mounted in the tethered valve deployment demonstration model  166 , e.g. left ventricle, right ventricle, body cavity, etc. and shows the struts  174 , strut bundle  152 , and tether  150  extending across the cavity and out through the body wall access port  154 . 
         [0087]      FIG. 20  shows a three-part triple-sheathed retrieval and removal catheter  258  having a flared outer dilator sheath  260  with an intermediate beveled catheter  240  disposed within and an inner catheter  242  having a tapered tip  256 , said inner catheter  242  disposed within the intermediate beveled catheter  240 . For removal, in operation the three-part catheter assembly uses the tapered tip  256  to engage and control the valve or device to be removed. The inner catheter  242  is then slightly withdrawn to allow the intermediate beveled catheter  240  to engage the struts  174  of the valve. Then, the intermediate beveled catheter  240  is slightly withdrawn to allow the outer-most flared dilator sheath  260  to compress and extract the valve. This multi-staged process allows the expandable valves, which have a large expansion force, to be compressed and withdrawn into a catheter. Without addressing such issues, such as is provided by these stages, there is an increased chance that the valve struts will break, the valve will be damaged, or the valve will get stuck and not be compressed, making catheter-based retrieval difficult and potentially unfeasible. 
         [0088]      FIG. 21  shows the two outermost catheters of the triple-sheathed retrieval and removal catheter  258  and shows a flared outer dilator sheath  260  with an intermediate beveled catheter  240  disposed within. 
         [0089]      FIG. 22  shows the assembled retrieval and removal catheter apparatus  258  and shows support rod  216  extending from the retaining collar  226  across a secondary collar  262  to the gated bore collar  228 , traveller strap  222  attached to the retaining collar  226  and sliding gate  230  mounted on the gated-bore collar  228 , with the triple-sheathed catheter  258  attached to a distal end of the gated-bore collar  228  and stylet  224  and inner catheter  242  extending through the axis of the entire apparatus. Key slot/Rod aperture  232  and distance markers  246  are shown along with rod screw  236 . In operation, the use of multiple stages requires the use of multiple catheter bases, with each engaging the support rod  216  and the retaining collar/inner catheter base  226  and secondary collar/intermediate base  262  operationally attached to the traveller strap for advancing the tethered valve in staged steps. 
         [0090]      FIG. 23  shows the triple-sheathed catheter  258  that has been advanced through the body wall access port  154  of the ventricle or cavity of the demonstration model  166 . Once the valve or device is under control, the valve or device is expelled from the annulus  170 .  FIG. 23  shows the tapered tip  256  of the inner catheter engaging the strut bundle  152  of the valve just prior to expelling the deployed valve from the annulus  170  into an atrial location of the demonstration model. 
         [0091]      FIG. 24  shows the triple-sheathed removal catheter  258  and shows the valve  168  partially withdrawn in the flared outer dilator sheath  260  after the inner catheter  242  (not seen) has taken control of the strut bundle  152  (not seen) using the tapered tip  256  and the intermediate beveled catheter  240  (not seen) has controllably collapsed and compressed the valve struts  174  (not seen). 
         [0092]      FIG. 25  shows the valve  168  being further drawn into the protective flared end of the flared outer dilator sheath  260 .  FIG. 25  also shows the outer dilator sheath catheter  260  extending across the lumen of the ventricle of the model with the gated-bore collar  228  outside of the body wall access port  154  (proximal side) and the valve being removed from inside an atrial space  172  of the demonstration model  166 . 
         [0093]      FIG. 26  shows the valve  168  being further drawn into the protective flared end of the flared outer dilator sheath  260 .  FIG. 26  also shows radio-marker band  266  at the tip of the outer catheter/dilator sheath  260 . Sliding gate  230  of dilator base/gated collar  228  is shown ‘outside’ of the cavity and sliding gate  230  is in the open (lumen) position which is used during valve removal. 
         [0094]      FIG. 27  shows the valve entirely removed and withdrawn into the outer catheter and out of the simulated body cavity  166 .  FIG. 27  shows luer  264  on the outer collar  228 . 
         [0095]    For convenience, the following parts list is provided corresponding to the drawing figures herein to assist in better understanding the inventive subject matter. 
       RETRIEVAL PARTS 
       [0000]    
       
         
           
               110  handle 
               112  actuator 
               114  spring 
               116  support rod 
               118  (strap) tensioning jaw 
               120  double-sheathed dilator assembly 
               122  (tensioning) strap 
               124  stylet 
               126  retaining collar/inner catheter base 
               128  gated bore collar/dilator base 
               130  sliding gate 
               132  key slot/guide rod aperture 
               134  tether screw 
               136  rod screw 
               138  dilator (outer) sheath 
               140  inner catheter 
               142  gasket 
               144  strut coupler 
               146  rod distance markers 
               148  capture wire 
               150  tether 
               152  strut bundle 
               154  body wall access port 
               156  tapered tip 
               158  radio band 
               162  collar stabilizer 
               164  collar luer 
               166  demonstration model 
               168  valve 
               170  annulus 
               172  atrial space 
               174  struts 
               210  handle 
               212  actuator 
               214  spring 
               216  support rod 
               218  (strap) tensioning jaw 
               222  (tensioning) strap 
               224  stylet 
               226  retaining collar 
               228  gated bore collar 
               230  sliding gate 
               232  key slot/rod aperture 
               234  tether screw 
               236  rod screw 
               240  intermediate beveled catheter 
               242  inner catheter 
               244  strut coupler 
               246  rod distance markers 
               248  capture wire 
               256  tapered tip 
               258  triple-sheathed dilator assembly 
               260  flared dilator (outer) sheath 
               262  secondary collar 
               264  collar luer 
               266  radio band 
           
         
       
     
         [0152]    The references recited herein are incorporated herein in their entirety, particularly as they relate to teaching the level of ordinary skill in this art and for any disclosure necessary for the commoner understanding of the subject matter of the claimed invention. It will be clear to a person of ordinary skill in the art that the above embodiments may be altered or that insubstantial changes may be made without departing from the scope of the invention. Accordingly, the scope of the invention is determined by the scope of the following claims and their equitable Equivalents.