Abstract:
An assembly for treating a native heart valve can include a prosthetic valve and a delivery apparatus. The prosthetic valve can include an expandable frame, a valve structure, a first end with apertures formed therein, and a second end. The delivery apparatus can include a valve catheter, flexible extension arms, slidable wires, and release members. First ends of the arms can be coupled to a cylindrical coupling element, second ends of the arms can be releasably coupled to the prosthetic valve, and the coupling element can be connected to the distal end of the valve catheter. The slidable wires can extend distally from the distal end of the valve catheter. The release members can be coupled to the distal end of the valve catheter and can extend through a respective aperture of the prosthetic valve, thereby forming a releasable connection between the prosthetic valve and the slidable wires.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. application Ser. No. 14/561,113, filed Dec. 4, 2014, which is a continuation of U.S. application Ser. No. 13/449,200, filed Apr. 17, 2012, now abandoned, which is a continuation of U.S. application Ser. No. 11/252,657, filed Oct. 18, 2005, now U.S. Pat. No. 8,167,932, the entire disclosures of which are incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to systems used to deliver medical implants into a human body. More particularly, the present invention is directed to a delivery system for delivering a prosthetic valve to a human heart. 
       BACKGROUND 
       [0003]    Catheter-based procedures are commonly used in medical practice to treat regions within the body that are not easily accessible by surgery or wherein access without surgery is desirable. In one catheter-based procedure, a prosthetic valve is delivered to a human heart using a percutaneous approach for replacing a defective native heart valve. Although the replacement of native heart valves using percutaneously delivered prosthetic valves has shown great potential, the effectiveness of this procedure is often limited by the operator&#39;s ability to navigate through the patient&#39;s vasculature, such as through small vessels and around the aortic arch. 
         [0004]    In one delivery method, a prosthetic valve is mounted on a balloon catheter. Before advancing the prosthetic valve to the heart, a guide sheath is introduced into the iliac artery of the patient. Although the guide sheath adds diameter and complexity to the system, the guide sheath is necessary for advancing the catheter and prosthetic valve through the relatively narrow arterial vessels. The balloon catheter and prosthetic valve are pushed by the operator through the guide sheath to the treatment site. In one shortcoming of this procedure, the balloon catheter may lack the pushability required to be effectively advanced through the guide sheath. Furthermore, after exiting the guide sheath, the prosthetic valve may come into contact with the inner wall of the vessel, such as along the aortic arch. As a result of this contact, the vessel wall may be damaged and advancement of the prosthetic valve may be impeded or prevented altogether. Furthermore, calcification and plaque can be dislodged from the vessel wall. 
         [0005]    Due to the shortcomings associated with existing delivery systems, there is a need for a new and improved delivery system that may be used to deliver a prosthetic valve to a human heart in a safe and effective manner. It is desirable that such a system does not require the use of a conventional guide sheath. It is also desirable that such a system eases the tracking process and reduces the displacement of plaque or calcification along the inner walls of the body vessels. It is also desirable that such a system has sufficient flexibility to track through the curves of a body vessel, while providing sufficient pushability to ensure that the prosthetic valve can be tracked to the native valve site. It is desirable that such a system also provides a means for deploying the prosthetic valve at the native valve site in a controlled and precise manner. The present invention addresses this need. 
       SUMMARY 
       [0006]    Preferred embodiments of a system for treating a native valve in a human heart include a delivery sleeve containing a prosthetic valve which enters a vessel without the use of a guide sheath. Entry without the use of a guide sheath is achieved by the gradual profile of a step balloon, the tip of which protrudes from the distal end of the delivery sleeve and provides a smooth transition from a guide wire to the delivery sleeve. 
         [0007]    The delivery sleeve is comprised of materials which give the catheter sufficient pushability, rigidity, and flexibility to allow an operator to accurately place the distal end of the catheter at a site where the prosthetic valve is to be deployed. The smooth transition of the step balloon prevents the loosening of calcification and plaque inside the vessel, and particularly in the area of the aortic arch. 
         [0008]    Another advantage of the system is the ability to prepare the site of the native valve for implantation of the prosthetic valve. It is advantageous to dilate the stenotic leaflets prior to implanting the prosthetic valve. The leaflets are dilated as the step balloon is deflated, passed through the opening between the leaflets, and then reinflated. 
         [0009]    Another advantage of the system is the ability to aid in crossing the site of the native valve for implantation of the prosthetic valve. The step balloon provides a smooth tapered tip that transitions to the sheath for easy crossing of the calcified leaflets. 
         [0010]    Yet another advantage of the system is the ability to retract the step balloon through the prosthetic valve after deployment. The tapered tip may be deflated and collapsed to facilitate retraction of the balloon through the prosthetic valve. This feature advantageously reduces or eliminates the possibility of damaging the prosthetic valve leaflets or snagging on the valve frame during retraction. 
         [0011]    At the site of valve deployment, the delivery sleeve retracts, allowing full expansion of the step balloon. The distal end of a valve catheter contains flexible extensions which flex outwardly as the balloon inflates. The prosthetic valve is connected to the flexible extensions, thereby providing improved stability and controllability during deployment. 
         [0012]    In one aspect, a system for treating a native valve in a human heart comprises a prosthetic valve, valve catheter and tubular delivery sleeve. The prosthetic valve includes an expandable frame and a valvular structure. The tubular sleeve is configured for advancement through a patient&#39;s vasculature. The tubular sleeve defines a passageway and the valve catheter is configured for slidable advancement through the passageway. A releasable engagement mechanism is disposed along a distal end portion of the valve catheter for engaging the prosthetic valve. An actuation mechanism is disposed along a proximal end portion of the valve catheter for causing the releasable engagement mechanism to release the prosthetic valve. 
         [0013]    In one variation, the releasable engagement mechanism comprises a plurality of flexible extension arms configured to hold the prosthetic valve during expansion of the prosthetic valve at a treatment site. The system may further comprise at least one suture for securing the prosthetic valve to the flexible extension arms. At least one slidable member is attached to the actuation mechanism and extends distally toward the prosthetic valve. The slidable member, such as a wire, is retractable for detaching the suture from the prosthetic valve, thereby releasing the prosthetic valve from the flexible extension arms. 
         [0014]    In another variation, the system may further comprise an expandable transition member extending from a distal end of the tubular sleeve. In one variation, the transition member comprises an inflatable balloon having a tapered distal end portion. The inflatable balloon is preferably disposed at least partially within the prosthetic valve such that inflation of the inflatable balloon assists in the expansion of the prosthetic valve. When the system includes an inflatable balloon, the expandable frame of the prosthetic valve may be balloon-expandable or self-expanding. In one variation, an expandable basket may be used in place of an inflatable balloon for providing a dilator or for facilitating expansion of the prosthetic valve. 
         [0015]    In another variation, a handle assembly may be provided for controllably retracting the tubular sleeve for exposing the prosthetic valve at the treatment site. In one embodiment, the handle assembly has a distal end portion attached to the tubular sleeve and a proximal end portion attached to the valve catheter. The handle assembly may utilize a lead screw of other suitable mechanism for advancing the valve catheter in a controlled manner and securely holding the relative positions of the valve catheter and tubular sleeve. 
         [0016]    In another aspect, a method of deploying a prosthetic valve within a native valve in a human heart is provided. The method includes providing an elongate valve catheter having a releasable attachment mechanism along a distal end portion. The prosthetic valve is attachable to the releasable attachment mechanism. The valve catheter and prosthetic valve are placed in a tubular sleeve. The tubular sleeve, valve catheter and prosthetic valve are advanced as a single unit through a femoral artery and over an aortic arch until the prosthetic valve is substantially located within the native valve. The delivery sleeve is retracted relative to the valve catheter to expose the prosthetic valve and an actuation mechanism on a proximal end of the valve catheter is actuated to release the prosthetic valve from the valve catheter. 
         [0017]    In one variation, an inflatable balloon is disposed within the prosthetic valve during advancement of the prosthetic valve. A tapered distal end portion of the inflatable balloon extends from the tubular sleeve for providing a dilator to facilitate advancement through the patient&#39;s vasculature. In another variation, the inflatable balloon may be used to dilate the native valve by pushing aside the stenotic leaflets, thereby facilitating insertion of the prosthetic valve into the native valve. In yet another variation, the inflatable balloon may be inflated after retracting the tubular sleeve to facilitate expansion and seat the prosthetic valve within the native valve. In yet another variation, preferred embodiments of the system allow the tubular sleeve to be advanced relative to the valve catheter after exposing the prosthetic valve. Advancement of the tubular sleeve causes the prosthetic valve to collapse again such that it may be repositioned in the event that the initial deployment is not desirable. After repositioning the prosthetic valve, the sleeve may be retracted again and the prosthetic valve may then be released from the valve catheter. 
         [0018]    In another aspect, a device for treating a human heart comprises a prosthetic valve, a tubular delivery sleeve having a proximal end, a lead screw nut coupled to the proximal end of the tubular delivery sleeve, and a valve catheter having a distal end configured for releasable attachment to the prosthetic valve, wherein the valve catheter and the prosthetic valve are slidably advanceable through the delivery sleeve. A lead screw is coupled to the valve catheter. The lead screw engages the lead screw nut and rotation of the lead screw causes the valve catheter and the prosthetic valve to advance relative to the delivery sleeve. In one variation, an inflatable balloon is disposed within the prosthetic valve for facilitating expansion of the prosthetic valve within the native valve. The inflatable balloon may have a tapered distal end portion configured to extend from the tubular delivery sleeve. Accordingly, the inflatable balloon may also be used to facilitate advancement through the vasculature and to dilate the stenotic leaflets of the native valve. The tubular delivery sleeve is preferably coated with a hydrophilic coating. In another variation, a plurality of flexible extensions is disposed along the distal end of the valve catheter, the flexible extension being configured for releasable attachment to the prosthetic valve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a side view of one preferred embodiment of a delivery system according to the present invention with a distal end cut away and shown in cross section; 
           [0020]      FIG. 2  is a side view of a balloon catheter of the delivery system; 
           [0021]      FIGS. 3A and 3B  are cross sectional and perspective views, respectively, of a balloon of the balloon catheter; 
           [0022]      FIG. 4  is a side view illustrating proximal and distal ends of a valve catheter which forms a portion of the delivery system; 
           [0023]      FIG. 5  is a cross sectional view of a multi-shaft lumen of the valve catheter; 
           [0024]      FIGS. 6A and 6B  are cross sectional and perspective views, respectively, of a collet of the valve catheter; 
           [0025]      FIGS. 7A and 7B  are cross sectional and perspective views, respectively, of a puck of the valve catheter; 
           [0026]      FIG. 8  is a perspective view of a mop of the valve catheter; 
           [0027]      FIG. 9  is a side cross sectional view of a delivery sleeve which forms a portion of the delivery system; 
           [0028]      FIG. 10  is a cross sectional view along a main portion of the delivery sleeve; 
           [0029]      FIG. 11  is a side cross sectional view of a proximal hub of the delivery system; 
           [0030]      FIG. 12  is a perspective view of a handle assembly attached to the delivery system; 
           [0031]      FIGS. 13A and 13B  are exploded and perspective views, respectively, of a distal plate assembly of the handle assembly; 
           [0032]      FIGS. 14A and 14B  are exploded and perspective views, respectively, of a proximal plate assembly of the handle assembly; 
           [0033]      FIG. 15  is a side view of a lead screw of the handle assembly; 
           [0034]      FIG. 16  is a perspective view of an embodiment of the handle assembly including a load cell; 
           [0035]      FIG. 17  is a perspective view of another embodiment of a handle assembly including a load cell; 
           [0036]      FIG. 18  is a side view of yet another embodiment of a handle assembly; 
           [0037]      FIG. 19  is a side view of the delivery system, with the proximal hub and distal end portion of the delivery system shown in cross section; 
           [0038]      FIG. 20  is a cross sectional view of an extension of the mop and corresponding prosthetic valve portion; 
           [0039]      FIG. 21  is a side view of the assembly between the alternative handle assembly of  FIG. 18  and the delivery system; 
           [0040]      FIGS. 22A and 22B  show the delivery system approaching a native valve site, and pushing away diseased native valve leaflets, respectively; 
           [0041]      FIGS. 23A to 23E  show a distal end portion of the delivery system during one preferred method of use for delivering and deploying a prosthetic valve. 
           [0042]      FIG. 24  is a side view of an alternative embodiment of the delivery system showing a mechanical basket tip. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    With reference now to  FIG. 1 , a heart valve delivery system  10  includes, generally, a guide wire  12  and a balloon catheter  14  having an inflatable balloon  18  located along a distal end portion. An expandable prosthetic valve  16  is located over the inflatable balloon. The balloon catheter  14  also includes an elongate balloon shaft  20 , and a support  22  at a proximal end thereof. The balloon shaft  20  of the balloon catheter  14  is received within a valve catheter  23 . As will be described in more detail below, the valve catheter  23  is configured for releasable engagement with the prosthetic valve  16 . The valve catheter  23  is received within a tubular delivery sleeve  24 , with the balloon  18  protruding, at least in part, from a distal end of the delivery sleeve  24 . A proximal end of the delivery sleeve  24  is mounted to a proximal hub  26 . A handle assembly  500 , which will be discussed and depicted in greater detail below, may be attached to the proximal hub  26  of the delivery sleeve  24  to effectuate controlled advancement of the prosthetic valve  16  relative to the delivery sleeve  24 . 
         [0044]    With reference to  FIG. 2 , the balloon catheter  14  is shown in greater detail. The balloon catheter  14  is provided with a guidewire shaft  31  that defines a guidewire lumen. The support  22  is located along a proximal end of the balloon catheter and includes a main shaft  32  and a fluid shaft  34  extending diagonally from the main shaft  32 . A stop cock  35  is located along the fluid shaft  34 . The main shaft  32  and the fluid shaft  34  each include a passageway, and the passageways are in communication with one another. A Touhy Borst valve  36 , such as described in U.S. Pat. No. 6,592,544, the contents of which are fully incorporated herein by reference, extends proximally from a proximal end of the main shaft  32 , and includes a tightening valve  37  at a proximal end thereof. The illustrated balloon shaft  20  is substantially tube shaped and includes an outer surface  38 . 
         [0045]    In one preferred construction, the balloon catheter  14  is assembled such that the outer surface  38  of the balloon shaft  20  is secured to an inner surface of the main shaft  32  of the support  22 . The Touhy Borst valve  36  is placed over the proximal end of main shaft  32  and secured thereto by a threaded connection between the two components. A compression valve inside the Touhy Borst valve  36  surrounds the guidewire shaft  31  and seals an inner passageway in the main shaft  32  of the support  22  from the atmosphere as the tightening valve  37  is tightened. 
         [0046]    With reference to  FIGS. 3A and 3B , the inflatable balloon  18  has a proximal end portion  40  and a distal end portion  42  and includes an inner surface  44 , an outer surface  46 , and a passageway  48  longitudinally extending therethrough. When viewed from the proximal end portion  40  to the distal end portion  42 , the illustrated embodiment of the balloon  18  includes seven regions: a first slender region  50 , a first conical region  52 , a main cylindrical region  54 , a second conical region  56 , a secondary cylindrical region  58 , a third conical region  60 , and a second slender region  62 . The balloon  18  is preferably inflated by a fluid, such as saline, and may be formed of any suitable material, such as, for example, nylon. The distal end portion  42  of the balloon  18  is preferably shaped to provide a transition member between the guidewire  12  and the relative large diameter delivery sleeve  24  (as shown in  FIG. 1 ), thereby facilitating advancement of the delivery system through the patient&#39;s vasculature. In preferred embodiments, the balloon  18  also provides a dilator tip, thereby eliminating the need for a separate dilator mechanism. The outer surface of the balloon and the delivery sleeve are preferably provided with a lubricious coating. The lubricious coating and the shape of the balloon allow the delivery system (including the prosthetic valve) to be advanced through relatively narrow and or calcified vasculature in a patient. Accordingly, in one advantageous feature, preferred embodiments of the delivery system may be used without a guide sheath. 
         [0047]    With reference to  FIGS. 1 through 3B , one preferred construction of the balloon  18  will now be described in more detail. The inner surface  44  of first slender portion  50  of the balloon  18  is secured to the outer surface  38  of the balloon shaft  20  at a distal end of the balloon shaft, thus placing the passageway of the balloon shaft  20  in communication with the passageway  48  of the balloon  18 . The inner surface  44  of the second slender portion  62  is secured to an outer surface  64  of the guidewire shaft  31 . The connection can be achieved by adhesion or by thermal joining, or both. A soft tip  68  having a passageway  70  extending therethrough is secured to the outer surface  64  of the guidewire shaft  31  at a distal end thereof, and extends distally from the guidewire shaft  31 , the passageway  70  of the soft tip  68  being in communication with a passageway  71  of the guidewire shaft  31 . 
         [0048]    With reference to  FIGS. 4 through 8 , the assembly and function of the valve catheter  23  will now be described. As best shown in  FIG. 4 , the valve catheter  23  provides a releasable engagement mechanism for holding and releasing the prosthetic valve  16 . In the illustrated embodiment, the valve catheter  23  includes a multi-lumen shaft  72 , around a proximal portion of which a stiffener tube  74  is disposed. A collet  76  extends from inside a central lumen of the multi-lumen shaft  72  and is snapped into a puck  78 . The puck  78  is snapped into the mop  80  such that the mop extends distally from the puck. The valve catheter  23  also includes a wire tube  82  extending proximally from a proximal end of the multi-lumen shaft  72 . The valve catheter  23  carries the prosthetic valve  16  to the native heart valve site and facilitates deployment of the prosthetic valve  16 , as described below. 
         [0049]    With reference to the cross-sectional view of  FIG. 5 , the multi-lumen shaft  72  is preferably cylindrically shaped and includes a central lumen  84  longitudinally extending therethrough. Six side lumens  86  extend from a proximal end to a distal end of the multi-lumen shaft  72 . In one embodiment, the multi-lumen shaft is made of a thermoplastic elastomer such as polyether block amide, known as Pebax®. 
         [0050]    With reference to  FIGS. 6A and 6B , the collet  76  is generally cylindrically shaped and includes a proximal end  90  and a distal end  92 . A central passageway  94  extends through the collet. Near the proximal end  90 , openings  96  extend from an outer surface  98  to an inner surface  100  of the collet  76 . Four longitudinal slots  102  pass from the outer surface  98  to the inner surface  100  along the distal end  92  of the collet  76 , thereby creating four flexible arms  104 . The slots  104  preferably narrow in width from the distal end  92  to the proximal end  90 . At the distal end  92  of the collet  76 , the outer surface preferably forms an angled surface  106  to facilitate engagement with the puck  78 . An annularly shaped flange  108  is located proximally adjacent to the angled surface  106 . Along the circumference of the collet  76 , the outer surface  98  includes a shoulder surface  109  which extends perpendicular to the outer surface  98  and faces the distal end  92  of the collet  76 . 
         [0051]    With reference to  FIGS. 7A and 7B , the puck  78  is generally tube shaped, having a central lumen  112  extending longitudinally therethrough from a proximal end  114  to a distal end  116 . The central lumen  112  is defined by an inner surface  118  of the puck  78 . An outer surface  120  of the puck  78  includes an angled portion  122  near the proximal end  114 . An annular groove  123  extends around the outer surface of the puck  78  distally adjacent the angled portion  122 . Near the distal end  116 , the outer surface  120  includes a snap ridge  124  extending around the circumference of the puck  78 . The snap ridge  124  is interrupted by four circular indentations  125  which extend from the outer surface  120 . The outer surface also includes an annularly shaped flange  126  extending outwardly which defines a shoulder surface  130 . Six side lumens  136  extend parallel to the central lumen  112  from the angled portion  122  of the outer surface  120  to the distal end  116  of the puck  78 . The side lumens  136  are equally spaced around the circumference of the puck  78 . A cylindrically shaped opening  138  extends radially from the outer surface  120  to the inner surface  118  of the puck  78 . A pin  139  is inserted into the opening  138 , situated flush with the outer surface and protruding inwardly from the inner surface  118  of the puck  78 . 
         [0052]    With reference to  FIG. 8 , the mop  80  is generally cylindrical in shape and includes a proximal end  140 , an outer surface  142 , an inner surface  144 , and a passageway  145  extending therethrough. The mop  80  preferably includes six elongate extensions  150  configured for engagement with the prosthetic valve. In one preferred embodiment, the extensions  150  have varying lengths configured for engaging different portions of the prosthetic valve. Each extension preferably includes first and second openings  152 ,  154  near a distal end  156 . Near the proximal end  140  of the mop  80 , four openings  146  extend from the outer surface  142  to the inner surface  144 , and are aligned along a circumference of the mop  80 . Four slots  148  passing from the outer surface  142  to the inner surface  144  extend from the proximal end  140  along the length of the mop  80  and pass between the openings  146 . The mop  80  is preferably formed of a shape memory material, such as Nitinol, or any other suitable material. 
         [0053]    With continued reference to  FIGS. 4 through 8 , during assembly of the valve catheter  23 , the puck  78  is snapped into the proximal end  140  of the mop  80 . The slots  148  allow the proximal end  140  of the mop  80  to flex as the distal end  116  of the puck is inserted into the passageway  145  of the mop  80  (see  FIGS. 7A and 8 ). The snap ridge  124  of the puck  78  enters the openings  146  of the mop  80 , and the slot indentations  125  of the puck  78  are aligned with the areas between the openings  146  of the mop  80 . The proximal end  140  of the mop  80  abuts the shoulder surface  130  of the puck  78 . The collet  76  snaps into the puck  78 . More particularly, the distal end  92  of the collet  76  passes through the proximal end  114  of the puck  78 . The arms  104  of the collet  76  flex to pass through the central lumen  112  of the puck  78 . The protrusion  138  of the puck  78  passes through one of the slots  102  of the collet  76 , and is pressed tight as the slot  102  narrows. Once snapped, the flange  108  of the collet  76  bears against the distal end  116  of the puck  78 , and the shoulder surface  109  of the collet  76  bears against the proximal end  114  of the puck  78 . 
         [0054]    The multi-lumen shaft  72  is placed proximally to the puck  78 . The proximal end  90  of the collet  76 , including the openings  96 , which may be filled with an adhesive material in order to ensure a strong bond, is inserted into the central lumen  84  of the multi-lumen shaft  72  such that the side lumens  86  of the multi-lumen shaft  72  are aligned with the side lumens  136  of the puck. The connection between the multi-lumen shaft  72  and the collet  76  can be made by thermal or adhesive joining, or both. The stiffener tube  74  is placed over the multi-lumen shaft  72  near the proximal end thereof. The stiffener tube  74  extends over a portion of the multi-lumen shaft  72 . The wire tube  82  is bonded to the proximal end of the multi-lumen shaft  72  and extends diagonally therefrom. 
         [0055]    With reference now to  FIGS. 9 and 10 , the delivery sleeve  24  preferably includes a proximal end  160 , a distal end  162 , an outer surface  164 , an inner surface  166 , and a passageway  168  extending longitudinally therethrough. The delivery sleeve  24  includes a main portion  170  and a tip portion  172 . The delivery sleeve  24  contains and protects the prosthetic valve during advancement through the patient&#39;s vasculature to the native valve site, as discussed below. The main portion  170  of the delivery sleeve  24  includes an inner layer  173 , over which is located a middle layer  174 , over which is located an outer layer  176 . The inner layer  173  of the main portion  170  of the delivery sleeve  24  is preferably formed of a material, such as Teflon®, having a low coefficient of friction. The middle and outside layers  174 ,  176  are preferably formed of Pebax®. At least a portion of the delivery sleeve may be coated with a lubricious material. The delivery sleeve  24  further includes a plurality of wires  178 , preferably made of stainless steel, which spiral along the length of the delivery sleeve  10 . 
         [0056]    The delivery sleeve  24  is preferably formed by an extrusion process. The wires are initially placed between the middle and outer layers of the delivery sleeve  24  during the extrusion process. The delivery sleeve  24  is then laminated by heat, causing the middle and outer layers to flow. The heat of the lamination process softens the middle and outer layers  174 ,  176 , causing the wires  178  to imbed into the middle and outer layers of the delivery sleeve  24 , as shown in  FIG. 10 . The inner layer  173 , which is preferably formed of Teflon®, does not flow when heated during the lamination process. 
         [0057]    In one preferred construction, half of the wires  178  spiral along the length of the delivery sleeve  24  in a direction opposite that of the other half of the wires  178 , such that the wires  178  cross one another to form a mesh. The wires  178  can also pass over and under one another to form a weave or a braid. The wires  178  extend from the proximal end  160  of the delivery sleeve  24  toward the distal end  162  in the main portion  170  of the delivery sleeve  24 . The tip portion  172  of the delivery sleeve  10  does not contain the wires  105 , which are placed in the main portion  170  of the delivery sleeve  24  to ensure adequate stiffness and pushability. 
         [0058]    The tip portion  172  of the delivery sleeve  12  is preferably made of soft material such as Pebax®. The wires  178  and the inner layer  172  are absent at the tip portion  172  of the delivery sleeve  24 . The tip portion  172  is configured such that the passageway  168  is the same size in the tip portion  172  of the delivery sleeve  24  as it is in the main portion  170  of the delivery sleeve  24 . Approaching the distal end  162  of the delivery sleeve, and in the tip portion  172  of the delivery sleeve  24 , the outer surface  164  tapers, forming a tapered outer surface  180 , which aids in the introduction and tracking of the delivery system  10  in the body vessel, as described below. 
         [0059]    At the transition between the main portion  170  and the tip portion  172  of the delivery sleeve, a radiopaque band  182  is disposed between the stainless steel wires  178  and outer layer  176  of the delivery sleeve  24 . During the heat lamination process described above, the radiopaque band  182  does not flow. After lamination is complete, the radiopaque band  182  remains surrounding the ends of the wires  178  and thus serves as a barrier between the outer layer  176  and the wires  178 . The radiopaque band  182  can comprise any suitable material, but is preferably made of an alloy comprising  90  percent platinum and  10  percent iridium (PLIR). 
         [0060]    With reference now to  FIG. 11 , a cross-sectional view along the proximal hub  26  of the delivery sleeve  24  is provided. The proximal hub  26  preferably comprises a cylindrically shaped hub body  200  having a passageway  201  extending longitudinally therethrough. The hub body  200  is partially surrounded by a housing  202  located at a distal end of the hub body  200 . An end piece  203  having an opening  204  extending into the passageway  201  of the hub body  200  is mounted to a proximal end of the hub body  200  and protrudes therefrom. An outer surface of the end piece  203  includes, when viewed from a proximal end to a distal end, a tapered surface  205 A, a first neck surface  205 B, a first shoulder surface  205 C facing distally, a second neck surface  205 D, and a second shoulder surface  205 E facing proximally. The first shoulder surface  205 C, the second neck surface  205 D, and the second shoulder surface  205 E define a groove  206  extending around the end piece  203 . 
         [0061]    Proximally adjacent the end piece  203  and inside the hub body  200 , a cross cut valve  207  is located, and is partially surrounded by a spacer  208 . Proximally adjacent the cross cut valve  206  and spacer  208  and inside the hub body  200 , a disc valve  210  is located. A duck bill valve  212  is also located inside the hub body  200 , proximally adjacent to the disc valve  210 . A hemostasis opening  212  extends from the passageway  201 , and a hemostasis tube  214  extends from the hub body  200  to a three-way stopcock  216 . One preferred embodiment of the proximal hub is described in greater detail in U.S. Pat. No. 5,968,068 entitled ENDOVASCULAR DELIVERY SYSTEM, the contents of which are fully incorporated herein by reference. 
         [0062]    With continued reference to  FIG. 11 , the delivery sleeve  24  is secured to the proximal hub  26 . The proximal end  160  of the delivery sleeve  24  is inserted into the passageway  201  of the proximal hub  26  at a distal end thereof. The outer surface  164  of the delivery sleeve  24  is secured to an inner surface of the housing  202  of the proximal hub  26  by an adhesive or thermal joining, thus placing the passageway  201  of the proximal hub in communication with the passageway  168  of the delivery sleeve  24 . 
         [0063]    With reference now to  FIG. 12 through 15 , one preferred embodiment of the handle assembly  500  will be described. The illustrated handle assembly  500  provides a mechanical actuation mechanism for advancing the prosthetic valve from the distal end of the delivery sleeve  24  in a controlled and precise manner The handle assembly  500  includes, generally, a distal plate assembly  502  coupled to the proximal hub  26  on the proximal end of the delivery sleeve  24 . The handle assembly also includes a proximal plate assembly  504  coupled to the valve catheter  23 . A lead screw  506  passes through the distal and proximal plate assemblies  502 ,  504 . 
         [0064]    With particular reference to  FIGS. 13A and 13B , the distal plate assembly  502  includes a main portion  510 , an upper portion  512 , and a lead screw nut  514 . The main and upper portions  510 ,  512  combine to include a first opening  516  passing through from a proximal face  518  to a distal face  520  of the distal plate assembly  502 . The first opening  516  is defined by a proximal opening surface  522 , a distal opening surface  524 , and a shoulder surface  525 . The proximal and distal opening surfaces  522 ,  524  extend perpendicularly from the proximal and distal faces  518 ,  520  of the distal plate assembly  502 . The shoulder surface  525  faces proximally and extends between the proximal and distal opening surfaces  522 ,  524 , substantially parallel to the proximal and distal faces  518 ,  520  of the distal plate assembly  502 . A second opening  526  in the distal plate assembly  502  extends from the proximal face  518  to the distal face  520 . Fastener openings  527  likewise extending through the distal plate assembly  502  are located in the area of the second opening  526 . 
         [0065]    The lead screw nut  514  is tube shaped, having an outer surface  528 , an inner surface  530 , and an opening  532  extending longitudinally therethrough. An outwardly extending flange  534  extends outwardly adjacent a proximal end  536  of the lead screw nut  514 . Fastener openings  538  pass through the flange  534  to the proximal end  536  of the lead screw nut  514 . The inner surface  530  of the lead screw nut  514  is threaded. 
         [0066]    The upper portion  512  of the distal plate assembly  502  is secured to the main portion  510  of the distal plate assembly  502  by distal plate assembly fasteners  540 , which engage distal plate assembly fastener holes  542 . The distal plate assembly fastener holes  542  pass through the upper portion  512  of the distal plate assembly  502  and into the main portion  510  of the distal plate assembly  502 . 
         [0067]    The lead screw nut  514  is secured to the main portion  510  of the distal plate assembly  502  as the proximal end  536  of the lead screw nut  514  is placed against the distal face  520  of the main portion  510 , and fastener openings  527  of the main portion  510  are aligned with the fastener openings  538  of the lead screw nut  514 . The opening  532  in the lead screw nut  514  is aligned with the second opening  526  of the distal plate assembly  502 . Lead screw nut fasteners  544  engage the fastener openings  527 ,  538  and secure the lead screw nut  514  to the main portion  510  of the distal plate assembly  502 . 
         [0068]    With reference to  FIGS. 14A and 14B , the proximal plate assembly  504  includes a main portion  546 , a cap portion  548 , and a handle  550  extending from the main portion  546 . The main portion  546  and cap portion  548  combine to create a central opening  552  passing through from a proximal face  554  to a distal face  556 . The central opening  552  is defined by a proximal opening surface  558 , a distal opening surface  560 , and an inner cavity surface  562 . The proximal and distal opening surfaces  558 ,  560  extend perpendicularly from the proximal and distal faces  554 ,  556  of the proximal plate assembly  504 . The inner cavity surface  562  runs between the proximal and distal opening surfaces  558 ,  560 , and creates an open cavity within the assembled proximal plate assembly  504 . 
         [0069]    A first side opening  564  in the proximal plate assembly  504  extends from the proximal face  554  to the distal face  556 . The handle  550  is secured to the main portion  546  of the proximal plate assembly  504  such that it passes through the first side opening  564  and is secured by a set screw  565 . A second side opening  566  in the proximal plate assembly  504  also extends from the proximal face  554  to the distal face  556 . The cap portion  548  of the proximal plate assembly  504  is secured to the main portion  546  of the proximal plate assembly  504  by proximal plate assembly fasteners  568 , which engage proximal plate assembly fastener holes  570 . The proximal plate assembly fastener holes  570  pass through the cap portion  548  of the proximal plate assembly  504  and into the main portion  546  of the proximal plate assembly  504 . 
         [0070]    With reference to  FIG. 15 , the lead screw  506  includes a rotator knob  572  at a proximal end thereof, a non-threaded portion  574 , and a threaded portion  576  adjacent a distal end thereof. The rotator knob  572  includes a neck portion  578  extending distally therefrom and from which the non-threaded portion  574  extends distally. A shoulder surface  580  at a distal end of the neck portion  578  of the rotator knob  572  faces distally. A groove  581  extends circumferentially around the lead screw  506 . 
         [0071]    With reference again to  FIGS. 12 through 15 , the handle assembly  500  is assembled as the lead screw  506  is placed through the second side opening  566  and lead screw nut opening  532  of the proximal plate assembly  504  and the second opening  526  of the distal plate assembly  502  such that the shoulder surface  580  of the rotator knob  572  abuts the proximal face  554  of the proximal plate assembly  504 . A snap ring  582  is placed in the groove  581  on the non-threaded portion  574  of the lead screw  506  such that it abuts the distal face  556  of the proximal plate assembly  504 . The snap ring  582  on the distal face  556  and the shoulder surface  580  on the proximal face  554  prevent translational movement of the lead screw  514  through the second side opening  556  of the proximal plate assembly  504 . The lead screw  506  rotates in the second side opening  556  of the proximal plate assembly  504 . The threaded portion  576  of the lead screw  506  engages the threaded inner surface  530  of the lead screw nut  514 . 
         [0072]    With reference to  FIG. 16 , an alternative embodiment of the handle assembly  500  is shown wherein the lead screw nut  514  is located proximally from the distal plate assembly  502 . A middle plate  590  surrounds the lead screw nut  514 , and lead screw nut fasteners  544  secure the middle plate  590  to the lead screw nut  514 . The middle plate  590  is secured to a load cell  592 , which is secured to the distal plate assembly  502 . The load cell  592  as shown in  FIG. 16  is known in the art, and may be connected as known in the art to a device (not shown) which measures the displacement on the load cell  592 . The device converts the displacement of the load cell  592  to the force being exerted to move the distal plate assembly  502  relative to the middle plate  590 . 
         [0073]    With reference to  FIG. 17 , another alternative embodiment of the handle assembly  500  includes a forked portion  594  of the middle plate  590  extending toward the handle  550 , which passes through an opening  596  of the forked portion  594 . A second handle  598  passes through the distal plate assembly  502 , and is secured by a second set screw  600 , which passes through the distal plate assembly  502  to contact the second handle  598 . A handle opening  602  in the distal assembly plate  502  allows the handle  550 , secured to the proximal plate assembly  504 , to pass through the distal plate assembly  502  unimpeded. 
         [0074]    With reference to  FIG. 18 , another alternative handle assembly  608  is illustrated wherein the proximal and distal plate assemblies are not required. A hollow shaft  610  includes snap members  612  extending parallel thereto. The snap members  612  are connected to the shaft  610  by bridges  614  extending between the shaft  610  and the snap members  612 . At a distal end, the snap members  612  include flanges  616  extending inwardly toward the shaft  610 , forming proximally facing surfaces  618 . A deployment knob  620  having an inner threaded surface is rotatably coupled to the shaft  610 . 
         [0075]    With reference now to  FIG. 19 , the functionality of the delivery system  10  will be described in more detail. The balloon catheter  14  is configured for insertion into the valve catheter  23 . The balloon shaft  20  is placed in the central lumen  84  of the multi-lumen shaft  72  and the outer surface  38  of the balloon shaft  20  is secured to an inner surface of the multi-lumen shaft  72 , such as, for example, by adhesion. The balloon shaft  20  extends from the support  22 , located proximal to the proximal end of the multi-lumen shaft  72 , through the central lumen  84  of the multi-lumen shaft  72 , through the passageway  94  of the collet  76 , through the central lumen  112  of the puck  78 , to the passageway  145  of the mop  80 . The main cylindrical portion  54  of the balloon  18  extends distally from the distal end  156  of the mop  80 . The prosthetic valve  16  is crimped sufficiently small to enter into the passageway  168  of the delivery sleeve  24 . The prosthetic valve  16  is supported by the main cylindrical portion  54  of the balloon  18  and is placed against the inner surface  166  of the delivery sleeve  24  in the area of the tip portion  172 , where it is contained while tracking to the native valve site. 
         [0076]    The delivery system  10  is preferably configured for use with a self-expanding prosthetic valve  16 . In one preferred embodiment, the prosthetic valve is formed, at least in part, of a memory material, such as Nitinol, wherein the prosthetic valve takes a rigid shape at a predetermined temperature, but is more malleable at lower temperatures. An example of such a self-expanding prosthetic valve is described in more detail in U.S. Patent Publication No. 2004/0186563 A1, published Sep. 23, 2004, the contents of which are fully incorporated herein by reference. It will be appreciated however, that many features of the present invention may also be used with other types of prosthetic valves, such as, for example, balloon expandable valves. Examples of preferred balloon expandable prosthetic valves are disclosed in U.S. Pat. No. 6,730,118 entitled IMPLANTABLE PROSTHETIC VALVE and U.S. Pat. No. 6,893,460, also entitled IMPLANTABLE PROSTHETIC VALVE, both of which are fully incorporated herein by reference. 
         [0077]    With continued reference to  FIG. 19 , the delivery sleeve  24  and proximal hub  26  are placed over the valve catheter  23 . The valve catheter  23  passes through the opening  204  of the end piece  203 , the passageway  201  of the proximal hub  26  (including valves  207 ,  210 , and  212 ), and the passageway  168  of the delivery sleeve  24  (see  FIG. 11 ). The proximal hub  26  is located near the proximal end of the valve catheter  23 , with the stiffener tube  74  entering the passageway  201  of the proximal hub  26  (see  FIG. 11 ) and extending proximally therefrom. The prosthetic valve  16  is located in the passageway  168  near the distal end  162  of the delivery sleeve  24  (see  FIG. 11 ). The self-expanding prosthetic valve  16  can be crimped to fit inside a delivery device when subject to temperatures lower than body temperature. The balloon  18  protrudes distally from the distal end  162  of the delivery sleeve  24 . 
         [0078]    The guide wire  12  is inserted into the passageway  71  of the guidewire shaft  31 . The guide wire  12  extends distally from the distal end of the guidewire shaft  31  and from the soft tip  68 , and proximally from a proximal end of the guidewire shaft  31 . 
         [0079]    A bonded wire  234  extends through the wire tube  82 . The bonded wire forms a portion of a preferred actuation mechanism for releasing the prosthetic valve from the valve catheter at the treatment site. The bonded wire  234  is formed from six individual wires which exit the wire tube  82  at a distal end thereof and enter the six side lumens  86  of the multi-lumen shaft  72 . A knob  236  sits on a proximal end of the bonded wire  234 . The six individual wires of the bonded wire  234  exit the distal end of the multi-lumen shaft and enter the side lumens  136  of the puck  78  (see  FIGS. 7A and 7B ). The six individual wires of the bonded wire  234  exit the side lumens  136  at the distal end  116  of the puck  78  and extend toward the distal end  156  of the mop  80 . 
         [0080]    Heat shrink  237  can be used to reinforce the connection between the multi-lumen shaft  72 , the wire tube  82 , and the balloon catheter  14 . The heat shrink  237  is placed over the wire tube  82 , the multi-lumen shaft  72 , and the main shaft  32  of the support  22 , and is heat treated until it forms a hardened shell around the components, thus securing them to one another and making the delivery system  10  more robust. 
         [0081]    With reference now to  FIG. 20 , one preferred means for releasably attaching the prosthetic valve  16  to the valve catheter will be described. In general terms, the prosthetic valve  16  is preferably attached to the mop  80  portion of the valve catheter (see  FIG. 8 ) by a flexible elongate member to provide a tether and snare mechanism. To accomplish this, one or more sutures  238  (tethers) are passed through portions of the prosthetic valve and through the mop  80  portion of the valve catheter. The sutures  238  preferably include loops that extend through portions of the prosthetic valve. Slidable wire(s)  234  extend through the loops to prevent the suture from detaching from the prosthetic valve. Therefore, the slidable wire(s)  234  provide a releasable snare mechanism that can be withdrawn for quickly and easily detaching the sutures from the prosthetic valve. 
         [0082]    In the preferred embodiment illustrated in  FIG. 20 , proximal end portions of the prosthetic valve  16  are placed near the second openings  154  on the inner surface  144  of the mop  80 . The six individual wires of the wire  234  extend from the side lumens  136  of the puck  78  (see  FIG. 7A ) and are pressed against the inner surface  144  of the extensions  150  of the mop  80 . The individual wires pass along the sides of the prosthetic valve  16 , with the prosthetic valve  16  placed between the inner surface  144  of the mop  80  and the individual wires. Distal ends of the individual wires can be tucked into a commissure pocket of the prosthetic valve  16  or between leaflets at a commissure post of the prosthetic valve  16  to avoid exposure to the delivery sleeve  24  while tracking and to the body vessel during valve deployment. 
         [0083]    An anchor, such as a ring formed of suture or other material, is preferably provided in the annular groove  123  of the puck  78  (see  FIG. 7A ). The suture  238  is tied into the anchor, and then passes therefrom along the outer surface  142  of the mop  80  (see also  FIG. 8 ), whereupon it passes through the first opening  152  of one of the extensions  150  of the mop  80 , wraps around the individual wire of the wire  234 , and returns to the outer surface  142  of the mop  80  through the first opening  152 . The suture  238  then passes through the second opening  154  of one of the extensions  150  of the mop  80 , through an attachment opening  239  of the prosthetic valve  16 , around the individual wire  234 , returns through the attachment point of the prosthetic valve  16 , and returns through the second opening  154  of the same extension  150  to the outer surface  142  of the mop  80 . The suture  238  is tied into the anchor at the annular groove  123  of the puck  78  such that it forms a suture loop extending from the anchor to the distal end  156  of the extension  150  of the mop  80  (see also  FIG. 8 ). The suture  238  is used to form a similar suture loop corresponding to each extension  150  of the mop  80 , with a tether or snare formed near the distal end  156  of each extension  150  of the mop  80 . The suture  238  is wrapped around itself and tied into a position aligned with each extension  150  of the mop before passing along the outer surface  142  of each extension  150  to form the suture loop. 
         [0084]    With reference again to  FIGS. 12 through 18 , attachment of the handle assembly  500  to the delivery system  10  will now be described in more detail. The proximal plate assembly  504  clenches the valve catheter  23 , which is inserted into the central opening  552  of the proximal plate assembly  504 . The stiffener tube  74  (see  FIG. 4 ) of the valve catheter  23  contacts the proximal and distal opening surfaces  558 ,  560  of the proximal plate assembly  504  (see  FIG. 14A ). The contact is sufficiently tight to secure the valve catheter  23  to the proximal plate assembly  504 . 
         [0085]    The distal plate assembly  502  is secured to the proximal hub  26 . The end piece  203  passes through the first opening  516  of the distal plate assembly  502  (see  FIG. 13B ), with the distal plate assembly  502  engaging the groove  506  of the end piece  203  (see  FIG. 11 ). The first neck surface  205 B of the end piece  203  (see  FIG. 11 ) bears against the proximal opening surface  522  of the distal plate assembly  502  (see  FIGS. 13A and 13B ). The first shoulder surface  205 C of the end piece  203  (see  FIG. 11 ) bears against the shoulder surface  525  of the distal plate assembly  502  (see  FIGS. 13A and 13B ). The second neck surface  205 D of the end piece  203  (see  FIG. 11 ) bears against the distal opening surface  524  of the distal plate assembly  502  (see  FIGS. 13A and 13B ). The second shoulder surface  205 E of the end piece  203  (see  FIG. 11 ) bears against the distal face  520  of the distal plate assembly  502  (see  FIGS. 13A and 13B ). 
         [0086]    The embodiments shown in  FIGS. 16 and 17  are well-suited for allowing the operator to be aware of the force being exerted on the prosthetic valve  16  while it is exiting the delivery sleeve  24 , described below. The embodiment shown in  FIG. 17  is suited to stabilize the handle assembly  500 , as the extended distal plate assembly  502  and second handle  598  cause an even distribution of weight about an axis defined by the valve catheter  23 . The forked portion  594 , in addition to serving as a means to evenly distribute weight about the axis defined by the valve catheter  23 , serves to prevent the device from rotating under the stresses present during valve deployment and operation of the lead screw  506 , described below. 
         [0087]    In the alternative embodiment shown in  FIG. 18 , the handle assembly  608  is attached to the delivery system  10  by snapping the shaft  610  into the proximal hub  26  (see  FIG. 11 ), as shown in  FIG. 21 . The shaft  610  enters the opening  204  of the end piece  203  (see  FIG. 11 ). The flanges  616  of the snap members  612  pass over the tapered surface  205 A and the first neck surface  205 B to engage the groove  206  (see  FIG. 11 ) of the end piece  203 . The proximally facing surfaces  618  of the snap members  612  bear against the first shoulder surface  205 C of the end piece  203  of the proximal hub  26 . The inner threaded surface of the deployment knob engages a threaded surface  622  of the valve catheter  23 . The threaded surface  622  of the valve catheter  23  can be incorporated into the stiffener tube  74  (see  FIG. 4 ) 
         [0088]    With reference now to  FIGS. 1 through 11 , preferred methods of using the delivery system  10  to deliver a prosthetic valve  16  will be described in more detail. The guide wire  12  is first inserted into a body vessel, such as the femoral artery, according to methods that are known in the art. The guide wire  12  passes through the arteries of the patient, and through an opening in the native valve. If desired, a dilator may be inserted over the guide wire  12  into the body cavity. One preferred dilator is described in more detail in U.S. Pat. No. 5,968,068 entitled ENDOVASCULAR DELIVERY SYSTEM, the contents of which are fully incorporated herein by reference. The dilator acts to enlarge the opening of the body vessel and thereby facilitate the passing of the delivery system  10  into the body vessel. After vessel dilation and entry of the delivery system  10  into the body vessel, the dilator is removed. However, as discussed above, embodiments of the delivery system  10  may be used without a dilator due to the shape and coating of the balloon and delivery sleeve. 
         [0089]    The delivery system  10  travels over the guide wire  12  and is introduced into the body vessel. A hydrophilic coating is preferably used to provide lubricity on the outer surface  46  of the balloon  18  (see  FIG. 3A ) and on the outer surface  164  of the delivery sleeve  24  (see  FIG. 11 ). A lubricious surface allows for easier introduction of the device, as well as easier tracking of the device to the site of the native valve, by decreasing the amount of friction between the walls of the body vessel through which the device is tracked. The outer surface  46  of the second cone portion  56  of the balloon  18  (see  FIGS. 3A and 3B ) provides a tapered surface for ease of entry into the body vessel. At the distal end  162  of the delivery sleeve  24 , the tapered surface  180  of the tip portion  172  of the delivery sleeve  24  (see  FIG. 9 ) also facilitates entry into the body vessel. 
         [0090]    With reference now to  FIG. 22A , the delivery system  10  passes over the guide wire  12  as it tracks to a native valve site  250 . Tracking occurs as the operator pushes the delivery system  10  through the femoral artery, over the aortic arch  254 , and to the native valve site  250  in a retrograde (i.e., against the blood flow) procedure. The balloon  18  may be used to act as a dilator within the body vessel during tracking. The body vessel may be constrictive due to size or calcification. The balloon  18  provides a tapered, soft surface, for gradual dilation of constrictive areas of the body vessel as the distal end of the delivery system  10  advances therethrough. If necessary, the balloon may be partially or entirely deflated and then re-inflated during advancement to further facilitate advancement through narrow vasculature. The structure of the delivery sleeve  24  gives it sufficient flexibility and pushability to track to the native valve site  250 . Fluoroscopy, wherein the position of the radiopaque band  182  of the delivery sleeve  24  (see  FIG. 9 ) can be seen relative the native valve site  250 , allows the operator to be aware of the position of the delivery system  10 . 
         [0091]    During tracking of the delivery system  10  to the native valve site, the delivery sleeve  24  bends in order to pass through the curves of the body vessels, including the curve found in the aortic arch  254 . The bending of the delivery sleeve  24  may cause the components of the valve catheter  23  to move relative to the inner surface  166  of the delivery sleeve  24  (see  FIG. 9 ). The bending may also cause the passageway of the delivery sleeve  24  to narrow, thereby increasing friction. Accordingly, preferred embodiments of the delivery sleeve  24  have an inner surface  166  formed or coated with a material having a low coefficient of friction such as Teflon®. 
         [0092]    As the delivery sleeve  24  bends while tracking to the native valve site  250 , a bending force is exerted on the wires  178  (see  FIG. 10 ). The force on the wires  178  may cause the wires  178  to press against the middle and outer layers  174  and  176  of the delivery sleeve  24 . Accordingly, the radiopaque band  182  (see  FIG. 9 ) is preferably formed from material that is sufficiently puncture resistant such that forces exerted by the ends of the wires  178  cannot puncture the outer layer  176  of the delivery sleeve  24  when the sleeve  24  is bending. The inner layer  173  of the delivery sleeve  24  (see  FIG. 10 ) also provides protection to the valve catheter  23  and balloon catheter  14  from the wires  178 . The material chosen for the inner layer  173  does not flow under the heat laminating process described above. The wires  178  do not become imbedded in the inner layer  173 . The inner layer  173  thus provides a barrier between the wires  178  and the passageway  168  of the delivery sleeve  24 . 
         [0093]    With reference to  FIG. 22B , once the delivery system  10  has arrived at the valve site, the operator can push the prosthetic valve  16  (see  FIG. 1 ) across native valve leaflets  256 , thus loosening the leaflets  256  that have become stenotic. Aortic stenosis is a disease of the aortic valve of the heart. Stenotic leaflets are thickened, hardened, and calcified; their movement is more limited than healthy leaflets. Stenotic leaflets inhibit blood flow, leaving only a small hole from which blood can be ejected into the aorta. Valve implantation can require that the leaflets be removed or pushed out of the way. However, the hardened nature of stenotic leaflets can complicate the loosening process. 
         [0094]    The balloon  18  is capable of stiffening when inflated and can be used to dilate stenotic leaflets of a native heart valve. The balloon  18  is deflated and the second cone portion  56  of the balloon  18  is passed through a small opening between the stenotic leaflets. The balloon  18  is then reinflated, as shown in  FIG. 22B , and the expanding balloon exerts sufficient pressure on the hardened tissue of the stenotic leaflets to dilate the leaflets. This dilation aids in the deployment of the prosthetic valve  16  (see  FIG. 19 ), described below. 
         [0095]    In a preferred method of valve deployment, the delivery sleeve  24  retracts as the valve catheter  23  is held steady, exposing the prosthetic valve  16  to an implantation site without requiring that the prosthetic valve track through the body cavity while exposed thereto. Further, there is no need to track the valve through a guide or introducer sheath, as it remains stationary with respect to the delivery sleeve  24  during introduction into the body vessel and during tracking therethrough. 
         [0096]    In the embodiment shown in  FIGS. 12, 16, and 17 , wherein the handle assembly  500  is employed, the operator turns the rotator knob  572  to retract the delivery sleeve and thereby expose the prosthetic valve to the body vessel and effect deployment. The threading of the threaded portion  576  of the lead screw  506  acts on the internal threading of the lead screw nut  514 , causing the lead screw nut  514  and the distal plate assembly  502  to translate toward the proximal plate assembly  504 , which is held translationally stationary relative to the lead screw  506  by the snap rings  582 . Thus, the distal and proximal plate assemblies  502 ,  504  move relative to each other, which causes the delivery sleeve  24 , which is attached to the distal plate assembly  502  at the end piece  203  of the proximal hub  26 , and the valve catheter  23 , which is secured to the proximal plate assembly  504 , to move relative to each other. 
         [0097]    In the alternative embodiment shown in  FIGS. 18 and 21  employing the alternative handle assembly  608 , the operator turns the deployment knob  620  such that the knob  620 , as well as the proximal hub  26  and delivery sleeve  24 , which are connected to the deployment knob  620 , travels proximally over the valve catheter  23 . 
         [0098]    The use of the lead screw  506  or the alternative handle assembly  608  potentially reduces the force needed to retract the delivery sleeve from the prosthetic valve  16 . One complete revolution of the lead screw  506  advances the lead screw nut  514  the distance between the individual threads on the threaded portion  576  of the lead screw  506 . The distance between threads, known as the pitch, determines the amount of force required by the operator to actuate the rotator knob  572 . The smaller the pitch, the less the translational movement is achieved per revolution of the rotator knob  572 . Less relative translational movement of the delivery sleeve  24  on one hand and the prosthetic valve and valve catheter  19  on the other hand, the less force required by the system operator. In a preferred embodiment of the present invention, the lead screw has a pitch of ¼ inch. 
         [0099]    In an alternative embodiment of the present invention not employing a lead screw, the operator holds the valve catheter  23  steady and pulls back (proximally) on the proximal hub  26 , which remains outside the body vessel, to expose the prosthetic valve to the body vessel and effectuate valve deployment. 
         [0100]    With reference now to  FIG. 23A , the delivery sleeve  24  is illustrated in the retracted position such that the prosthetic valve  16  and the extensions  150  of the mop  80  are exposed. The tip portion  172  of the delivery sleeve  24  is sufficiently flexible to allow retraction of the delivery sleeve  24  during valve deployment despite the pressure exerted on the delivery sleeve  24  by the expanding prosthetic valve. In order for the retraction of the delivery sleeve  24  to be more easily executed by the operator, the inner layer  173  of the delivery sleeve  24  (see  FIG. 9 ) may be formed of a material with a low coefficient of friction, such as Teflon®. 
         [0101]    With reference to  FIG. 23B , the balloon  18  can be deflated while the self-expanding capabilities of the prosthetic valve  16  cause it to expand outwardly. The extensions  15  of the mop  80  are preferably sufficiently flexible such that the extensions may allow expansion of the valve while maintaining the connection with the valve  16 . With reference to  FIG. 23C , after the prosthetic valve  16  has initially expanded, the balloon  18  may be inflated again to further increase the diameter of the prosthetic valve  16 . The additional expansion ensures that the prosthetic valve assumes a fully expanded condition whereby the valve is securely seated at the site of the native valve  250 . During expansion of the prosthetic valve, the leaflets  256  at the native valve site  250  are pressed against the wall of the aorta. As discussed above, the balloon  18  is inflated by a fluid source attached to the fluid shaft  34  of the support  22  of the balloon catheter  14  (see  FIG. 2 ). The stop cock  35  controls the flow of fluid into the main shaft  32  and the balloon shaft  20  of the balloon catheter  14  (see  FIG. 2 ). The compression valve of the Touhy Borst valve  36  prevents fluid leakage from the balloon catheter  14  (see  FIG. 2 ). 
         [0102]    The extensions  150  of the mop  80  flex outwardly to accommodate expansion of the prosthetic valve  16 . During expansion of the prosthetic valve  16  as shown in  FIGS. 23B and 23C , the operator can adjust the position of the prosthetic valve by advancing or retracting the valve catheter  23  of the delivery system  10 . The extensions  150  of the mop  80  possess sufficient stiffness to allow the position of the prosthetic valve  16  to be manipulated with a minimum amount of control. Prior to valve deployment, control of valve positioning is achieved by the operator pushing, pulling, or twisting the valve catheter  23 . The connection between the valve catheter  23  and the balloon catheter  14  allows for movement of the valve catheter  23  to be transmitted from the valve catheter  23  to the balloon catheter  14 . 
         [0103]    With reference to  FIG. 23D , it is to be understood that the relative movement between the valve catheter  23  and the delivery sleeve  24  during valve deployment can be reversed, by reversing the direction of rotator knob  572  (or deployment knob  620 ) or by manually pushing (distally) the proximal hub  26  while holding the inner catheter  23  steady. In one advantageous feature, the delivery sleeve may be moved (i.e., advanced) relative to the valve catheter after initial deployment to reduce the diameter of the valve if the location and/or orientation of the valve is not desirable. More particularly, as the distal end  162  of the delivery sleeve  24  advances distally over the extensions  150  of the mop  80 , the extensions  150  are pushed inwardly. As the extensions are pushed inwardly, the prosthetic valve is collapsed. Therefore, if the operator is not satisfied with the initial deployment of the prosthetic valve  16 , the operator can collapse and reorient the prosthetic valve  16 . As a result, the delivery system may be used to retract the prosthetic valve partially or entirely back into the delivery sleeve such that the prosthetic valve can be redeployed or withdrawn altogether. 
         [0104]    With reference to  FIG. 23E , once the operator is satisfied with the position in which the prosthetic valve  16  is being seated, the prosthetic valve is detached from the extensions  150  of the mop  80 . To disconnect the prosthetic valve  16  from the valve catheter  23 , the pulls on the knob  236  connected to the bonded wire  234  (see  FIG. 19 ). The distal ends of the six individual wires of the wire  234  are pulled from the commissure pockets and valve leaflets and from the suture  238 , allowing the suture to exit the attachment point of the prosthetic valve  16  and thus freeing the suture  238  from the prosthetic valve  16  (see  FIG. 20 ). The prosthetic valve  16  is then detached from the valve catheter  23 . Detachment of the prosthetic valve  16  can occur at any time that the operator deems appropriate, but usually occurs when the extensions  150  have expanded outwardly to their fullest extent. 
         [0105]    After releasing the prosthetic valve  16 , the valve catheter  23  and balloon catheter  14  are preferably returned to the passageway  168  of the delivery sleeve  24  (see  FIG. 11 ). To return the valve catheter  23  and balloon catheter  14  to the passageway  168  of the delivery sleeve  24  in those embodiments of the invention including the handle assemblies  500 ,  608  (see  FIGS. 12 and 21 ), the operator reverses the direction of rotator knob  572  or deployment knob  620 . In the alterative embodiment not employing a lead screw, the surgeon pulls (proximally) on the valve catheter  23  and balloon catheter  14  while holding the delivery sleeve  24  stationary (see  FIG. 1 ). The delivery system  10  is then withdrawn from the body vessel of the patient. 
         [0106]    Although preferred embodiments described herein include a balloon catheter which may be used as a dilator tip and may also be used to help seat the prosthetic valve, it will be appreciated that the system may be used without a balloon catheter. When no balloon catheter is provided, the prosthetic valve is released from the valve catheter and self-expands with sufficient force to firmly implant itself at the treatment site. In another variation of the preferred embodiments described herein, the delivery system may be configured such that the balloon catheter and the valve catheter form an integrated unit. 
         [0107]    With reference to  FIG. 24 , in another alternative embodiment, the transition member protruding distally from the delivery sleeve  24  may take the form of a mechanical basket  700  to facilitate entry into the body vessel and tracking to the native valve site. The mechanical basket includes struts  702  enveloped in a urethane covering  704 , which is secured over the guidewire shaft  31  at a distal end and a basket shaft  705  at a proximal end. The struts  702  are formed with laser cut tubing. The struts can be heat set to flex outwardly, and preferably are formed of super elastic Nitinol in order to expand and collapse effectively. The urethane covering  704  provides a smooth rounded tip for tracking through the aorta. During tracking, the basket  700  protrudes from the distal end  162  of the delivery sleeve  24 . 
         [0108]    The basket shaft  705  passes through the balloon shaft  20 . The balloon  18  is secured over the basket shaft  705  at the distal end  42  (see  FIGS. 3A and 3B ) and to the balloon shaft  20  at a proximal end  40  (see  FIGS. 3A and 3B ). The balloon shaft  20  passes through the delivery sleeve  24 . 
         [0109]    The guidewire shaft  31  protrudes distally from the basket shaft  705  and includes a pull wire  706  extending from a distal end of the guidewire shaft  31 , where it is attached, through the basket, and to the proximal end of the delivery system  10 , where it can be operated to expand or collapse the basket  700 . The guidewire shaft  31  and basket shaft  705  pass through the delivery system  10  and protrude proximally from the support  22  (see  FIG. 2 ). The basket shaft  705  protrudes proximally from the guidewire shaft  31 . The guidewire shaft  31  and basket shaft  705  can move relative to each other as the operator holds the basket shaft  705  steady and pushes or pulls the guidewire shaft  31 . The operator can also use the pull wire  706  to achieve relative movement between the guidewire shaft  31  and the basket shaft  705 . Relative movement between the shafts  31 ,  705  at a distal end causes the struts  702  of the basket  700  to flex inwardly or outwardly as the distal and proximal end of the basket move away from or toward one another. 
         [0110]    While tracking to the native valve site, the basket  700  protrudes distally from the distal end  162  of the delivery sleeve  24 . The shape of the basket  700  provides a tapered surface for ease of transition into the body vessel, and for ease of tracking through the body vessel to the native valve site, similar to the balloon  18 , as described above. 
         [0111]    In the alternative embodiment shown in  FIG. 24 , relative movement between the guidewire shaft  31  and the basket shaft  705  is used to collapse and expand the struts  702  of the basket  700 . The urethane covering  704  collapses with the struts  702 . The mechanical basket  700  can be collapsed and expanded to loosen stenotic leaflets, or dilate constrictive portions of the body vessel. The prosthetic valve  16  can be placed on the balloon  18  and in the delivery sleeve  24 , as in the other embodiments discussed herein, and valve deployment can occur similarly as in the other embodiments discussed herein. 
         [0112]    While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description and not of limitation. Therefore, changes may be made within the scope of the appended claims without departing from the true scope and spirit of the invention.