Abstract:
A catheter assembly according to the present invention includes a handle assembly, an introducer sheath, and a distal tip assembly. The distal tip assembly can include first and second retaining sleeves and a slotted tip with a non-traumatic tip guard positioned at the proximal end of the slotted tip. The handle assembly can include a fixed main handle and two or more rotating handles that allow a user to control the distal tip assembly of the catheter. Each control knob on the handle assembly controls a portion of the components on the distal tip of the catheter by allowing for precise manipulation of various delivery shafts. Each delivery shaft extends from the handle assembly to respective positions towards the distal end of the catheter.

Description:
BACKGROUND 
       [0001]    Field 
         [0002]    The present invention relates to catheters for delivering a prosthesis and, particularly, to delivery catheters having an a traumatic distal tip assembly. 
         [0003]    Background 
         [0004]    Recently, minimally invasive approaches have been developed to facilitate catheter-based implantation of prostheses, for example, transcatheter aortic-valve prosthesis implantation. Typically, during transcatheter prosthesis implantations, a prosthesis is radially contracted onto a delivery catheter so that the prosthesis can be introduced into a body lumen, for example, into the femoral artery, the brachial artery, or the aorta, or into a body cavity, for example, a chamber of the heart (e.g., the ventricle). The contracted configuration of the prosthesis on the delivery catheter can be maintained by a retaining sleeve positioned over the prosthesis. Using the delivery catheter, the prosthesis can then be guided to the desired implantation site through the body lumen or body cavity. Once the prosthesis is advanced to a desired target site, the prosthesis can be deployed by removing the retaining sleeve and allowing the prosthesis to expand, for example, through balloon expansion or self-expansion. 
         [0005]    A delivery catheter sometimes must be navigated through the tortuous anatomy of a body lumen or cavity. As the catheter articulates through the tortuous anatomy, the retaining sleeve can bend. The bending action of the retaining sleeve can cause the distal, leading edge of the retaining sleeve to flex outward (e.g., “fishmouth”) from an adjacent distal tip of the delivery catheter, exposing the distal edge. The exposed edge of the retaining sleeve can contact the wall of the body lumen or cavity, which can cause damage to the wall, especially in diseased body lumens. For example, during a trans-femoral delivery of a heart valve prosthesis, the delivery catheter must navigate around the aortic arch, which can cause the retaining sleeve to bend and can expose the retaining sleeve&#39;s distal, leading edge. The exposed leading edge of the retaining sleeve may damage the aortic wall if the edge contacts the wall. 
         [0006]    Accordingly, there is a need for delivery catheters that have an atraumatic distal tip assembly that can reduce the risk of damage to the walls of the body lumen or cavity that may occur during delivery of a prosthesis to a desired target site. 
       BRIEF SUMMARY 
       [0007]    A catheter for implanting a prosthesis can include a retaining sleeve that defines a hollow cavity. The retaining sleeve can contain a prosthesis. The retaining sleeve has an outer diameter. The catheter can also have a distal tip assembly configured to move axially relative to the retaining sleeve. The distal tip assembly can have a distal portion and a proximal portion. The proximal portion can be configured to move between a contracted position having a first outer diameter and an expanded position having a second outer diameter. The second outer diameter being larger than the outer diameter of the retaining sleeve. 
         [0008]    A method of implanting a prosthesis can include inserting a retaining sleeve and a distal tip assembly of a catheter assembly into a body lumen. The retaining sleeve can be positioned over the prosthesis. The retaining sleeve has an outer diameter. The distal tip assembly can have a distal portion and a proximal portion. The method can also include expanding the outer diameter of the proximal portion of the distal tip assembly such that the outer diameter of the proximal portion is larger than the outer diameter of the retaining sleeve. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]    The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the relevant art(s) to make and use the invention. 
           [0010]      FIG. 1  illustrates a delivery catheter according to an embodiment. 
           [0011]      FIG. 2  illustrates a distal tip assembly and a retaining sleeve of a delivery catheter according to an embodiment. 
           [0012]      FIG. 3  illustrates a cross-sectional view of the distal tip assembly and the retaining sleeve of  FIG. 2  according to an embodiment. 
           [0013]      FIG. 4  illustrates a distal tip assembly and an introducer of a delivery catheter according to an embodiment. 
           [0014]      FIG. 5  illustrates a cross-sectional view of the distal tip assembly and the introducer of  FIG. 4  according to an embodiment. 
           [0015]      FIG. 6  illustrates the distal tip assembly and the introducer of  FIGS. 4 and 5  according to an embodiment. 
           [0016]      FIG. 7  illustrates a biasing member according to an embodiment. 
           [0017]      FIG. 8  illustrates a cross-sectional view of the biasing member of  FIG. 7  and a distal tip assembly of a delivery catheter according to an embodiment. 
           [0018]      FIG. 9  illustrates a cross-sectional view of a distal tip assembly according to an embodiment. 
           [0019]      FIG. 10  illustrates an enlarged cross-sectional view of the distal tip assembly of  FIG. 9 . 
           [0020]      FIG. 11  illustrates a cross-sectional view of a distal tip assembly having a biasing member according to an embodiment. 
           [0021]      FIG. 12  illustrates the distal tip assembly and the biasing member of  FIG. 11  according to an embodiment. 
           [0022]      FIG. 13  illustrates the distal tip assembly and the biasing member of  FIGS. 11 and 12  according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The following description of prosthesis delivery catheters and methods of delivering and implanting a prosthesis refers to the accompanying figures that illustrate exemplary embodiments. Other embodiments are possible. Modifications can be made to the embodiments described herein without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not meant to be limiting. Further, it would be apparent to one of skill in the art that the systems and methods described below can be implemented in many different embodiments of hardware. Any actual hardware described is not meant to be limiting. The operation and behavior of the systems and methods presented are described with the understanding that modifications and variations of the embodiments are possible given the level of detail presented. For example, the delivery catheter described below can be adapted for use with different types of prostheses, for example, heart valve prostheses, stents, or valves prostheses for areas of the body other than the heart, and for different approaches, for example, transapical, subclavian, brachial, or trans-femoral. One of skill in the art would readily understand how to incorporate the features and structures described herein into catheters intended for other purposes. 
         [0024]      FIG. 1  illustrates a catheter assembly  100  according to an embodiment. Catheter assembly  100  generally includes a handle assembly  102  located at the proximal end of the catheter, a distal tip assembly  104  located at the distal end of the catheter, and an introducer  116  slidably located along an outer delivery shaft  106  extending from handle assembly  102 . Outer delivery shaft  106  can be tubular. Outer delivery shaft  106  can be formed of braided material fabricated from, for example, polyethylene naphthalate (PEN), polyester (PET), stainless steel, titanium, nitinol, cobalt nickel alloy, polyamide, polyimide, or the like. In sonic embodiments, outer delivery shaft  106  can have a degree of flexibility, for example, outer delivery shaft  106  is capable of articulating around a bend in a body lumen while still having sufficient axial strength to prevent buckling during delivery. Other suitable flexible materials can also be used to form outer delivery shaft  106  in other embodiments. 
         [0025]    Handle assembly  102  can include a main handle  108 , a proximal control knob  110 , and a distal control knob  112 . Main handle  108 , a proximal control knob  110 , and distal control knob  112  can be formed of any suitable material. For example, in some embodiments the handle and control knobs are formed of a polymer material. Other materials are possible, as would be understood in the art. It is understood that the handle and control knob, for example, need not be made of the same material. 
         [0026]    Handle assembly  102  can include a flushing port  114  on main handle  108 . Flushing port  114  can, for example, be used to de-air the catheter assembly, to introduce fluid into the native annulus to prevent coagulation and/or thrombosis, to deliver site specific drugs, or to introduce radiopaque fluid into the body. 
         [0027]    Catheter assembly  100  can include a flushing tap  118  and a flushing tap lead  120  connected to introducer  116 . Introducer  116  can be a tubular member that is slidably located over outer delivery shaft  106 . Introducer  116  can be formed of a variety of materials, for example, stainless steel or various polymer materials. 
         [0028]    Catheter assembly  100  further includes a prosthesis retaining sleeve  130  and a prosthesis retaining sleeve connector  134 . Prosthesis retaining sleeve  130  can be a tubular cylinder that defines a hollow cavity configured to receive a contracted prosthesis, for example, a heart valve prosthesis. Accordingly, prosthesis retaining sleeve  130  maintains the contracted configuration of the prosthesis on the delivery catheter assembly  100 . Prosthesis retaining sleeve connector  134  secures prosthesis retaining sleeve  130  to the distal end of outer delivery shaft  106 . Outer delivery shaft  106  extends distally from the interior of handle assembly  102  to sleeve connector  134 . 
         [0029]    Proximal control knob  110  and distal control knob  112  can be manipulated by a user to control operation of distal tip assembly  104 , a prosthesis retaining sleeve  130 , or both. In one embodiment, prosthesis retaining sleeve  130  and distal tip assembly  104  are configured to move axially relative to each other. For example, prosthesis retaining sleeve  130  connected to delivery shaft  106  can be advanced proximally, while keeping distal tip assembly  104  stationary, such that prosthesis retaining sleeve  130  moves away from distal tip assembly  104  to an open configuration as shown in  FIG. 1 . Prosthesis retaining sleeve  130  can be advanced distally, while keeping distal tip assembly  104  stationary, such that the prosthesis retaining sleeve  130  moves towards distal tip assembly  104  until the distal edge of retaining sleeve  130  is adjacent and, in some embodiments, abuts distal tip assembly  104  to a closed configuration (as shown in  FIG. 2 ). Alternatively or conjunctively, distal tip assembly  104  can be configured to move axially in the proximal and distal directions. Accordingly, to move catheter assembly  100  into the open configuration as shown in  FIG. 1 , distal tip assembly  104  and intermediate delivery shaft  132  to which distal tip assembly  104  is attached can be advanced distally while keeping retaining sleeve  130  stationary. To move catheter assembly  100  into the closed position, distal tip assembly  104  and intermediate delivery shaft  132  can be advanced proximally towards prosthesis retaining sleeve  130 . 
         [0030]    Distal tip assembly  104  is positioned on and connected to the distal end of intermediate delivery shaft  132 . Intermediate delivery shaft  132  extends from the interior of handle assembly  102  to distal tip assembly  104 , to which the distal end of intermediate delivery shaft  132  is attached. Intermediate delivery shaft  132  is encompassed by outer delivery shaft  106  from the interior of handle assembly  102  until outer delivery shaft  106  terminates at sleeve connector  134 . 
         [0031]    Intermediate delivery shaft  132  can be a tubular member, in one embodiment, a guide wire shaft  138  (see, e.g.,  FIGS. 3 and 8-11 ) is encompassed within intermediate delivery shaft  132  and extends from the inside of handle assembly  102  to the distal end of distal tip assembly  104 . Accordingly, catheter  100  can be configured to be advanced along a guide wire (not shown), for example, a guide wire having a 0.035 inch diameter. However, the dimensions of the catheter components can be adjusted for advancement over guide wires with larger or smaller diameters. 
         [0032]    In one embodiment, at least three shafts (for example, delivery shaft  106 , intermediate shaft  132 , and guide wire shaft  138 ) extend from handle assembly  102 , and the shafts are nested along at least a part of their lengths. Guide wire shaft  138  is encompassed by intermediate delivery shaft  132  from a position inside of handle assembly  102  to a proximal portion  124  of distal tip assembly  104 , which can be hollow through at least a portion thereof. Intermediate delivery shaft  132  is connected to, and ends at, proximal portion  124  of distal tip assembly  104 . In turn, intermediate delivery shaft  132  is encompassed by outer delivery shaft  106  from a position inside handle assembly  102  to the prosthesis retaining sleeve connector  134 . Outer delivery shaft  106  is connected to, and ends at, the retaining sleeve connector  134 . Intermediate delivery shaft  132  and guide wire shaft  138  can be constructed of various polymer materials. Persons of ordinary skill in the art would appreciate that the lengths and configurations of introducer  116 , delivery shaft  106 , intermediate delivery shaft  132 , and guide wire shaft  138  can be modified depending on the application. 
         [0033]    In one embodiment, distal tip assembly  104  includes a distal portion  122  and proximal portion  124 . Distal portion  122  can have any suitable atraumatic shape, for example, a shape that does not have any blunt edges. Atraumatic shapes can include, for example, a semi-spherical shape, a conical shape with a rounded distal tip (as illustrated in  FIGS. 1-13 ), or any other suitable atraumatic shapes. Distal portion  122  can be made of any suitable flexible material, for example, a polymer material, to prevent trauma to the wall of a body lumen or cavity. Distal portion  122  can function as a solid dilator tip, in one embodiment, distal portion  122  cannot expand the outer diameter does not change. 
         [0034]    Proximal portion  124  can be configured to move from a contracted position to an expanded position having a larger outer diameter. Proximal portion  124  can have an outer diameter in the expanded position that is larger than an outer diameter of prosthesis retaining sleeve  130 . In one embodiment, the outer diameter of proximal portion  124  is larger than the outer diameter of retaining sleeve  130  at its distal edge. In the expanded position, proximal portion  124  can have any suitable profile, for example, an arcuate profile (in which the largest outer diameter occurs at a central portion of proximal portion  124 ), a straight profile (in which the outer diameter is constant along the entire length of proximal portion  124 ), or a tapered profile (in which the outer diameter increases as proximal portion  124  extends proximally, for example, such that a proximal end of proximal portion  124  has the largest outer diameter). 
         [0035]      FIG. 2  illustrates a distal tip assembly  104  and retaining sleeve  130  according to an embodiment. Retaining sleeve  130  is positioned over prosthesis  200 , for example, a heart valve prosthesis. Proximal portion  124  is in a contracted position such that the outer diameter of proximal portion  124  is substantially the same as the outer diameter of prosthesis retaining sleeve  130 . Proximal portion  124  can include a balloon element  126 . Balloon element  126  can be a flexible member capable of containing a fluid, for example, air or water. Balloon element  126  can be inflated by a change in pressure and, particularly, an increase of pressure on an interior side of balloon element  126 . Balloon element  126  can encircle the outer contour of proximal portion  124 . As shown in  FIG. 2 , distal tip assembly  104  and retaining sleeve  130  are in the closed configuration in which proximal portion  124  is adjacent and, in some embodiments, abuts prosthesis retaining sleeve  130 . 
         [0036]      FIG. 3  illustrates distal tip assembly  104  with proximal portion  124  in an expanded position according to an embodiment. Distal tip assembly  104  and retaining sleeve  130  are in the closed configuration such that proximal portion  124  is adjacent to the distal, leading edge of retaining sleeve  130 . Proximal portion  124  is in an expanded position such that the outer diameter of proximal portion  124  is larger than the outer diameter of valve retaining sleeve  130 . As shown in  FIG. 3 , proximal portion  124  has an arcuate outer profile. In this position, the enlarged outer diameter of proximal portion  124  provides an atraumatic cushion for the distal edge of retaining sleeve  130  should it flare outward during delivery, for example, while navigating a tortuous bend in a body lumen or cavity. The proximal portion  124  would contact the wall before the edge of retaining sleeve  130  and deflect distal tip assembly  104  and retaining sleeve  130  away from the wall. 
         [0037]    Proximal portion  124  includes balloon element  126 . Balloon element  126  forms a seal with interior portion  142  and/or distal portion  122  to form outer cavity  140  for receiving a fluid, for example, air, or water. 
         [0038]    In one embodiment, proximal portion  124  can also include an interior portion  142  that extends proximally from distal portion  122 . Interior portion  142  can be cylindrical and can define a center cavity  144 . Center cavity  144  can be sized and configured to closely receive intermediate shaft  132 , forming a fluid seal. Interior portion  142  can define an aperture  146  in communication with cavity  140  and center cavity  144 . Guide wife shaft  138  can be sized and configured such that its outer diameter is spaced apart from the inner diameter of intermediate shaft  132 . The gap between guide wire shaft  138  and intermediate shaft  132  can he used as a fluid passage for transferring fluid to or from cavity  140  to change the pressure and, thus, expand or contract balloon element  126 . 
         [0039]      FIG. 4  illustrates distal tip assembly  104  and introducer  116  according to an embodiment. Distal tip assembly  104 , including proximal portion  124 , is within introducer  116 . Proximal portion  124  can include a biasing member  152  (see  FIG. 5 ). Biasing member  152  can bias proximal portion  124  outward against introducer  116 . In this embodiment, introducer  116  prevents the outer diameter of proximal portion  124  from being significantly greater, if at all, than the outer diameter of retaining sleeve  130 . 
         [0040]      FIG. 5  is a cross-sectional view of distal tip assembly  104  according to an embodiment. Proximal portion  124  includes an annular flange  128  that extends proximally from the proximal end of distal portion  122 . Annular flange  128  can be flexible, for example, annular flange  128  is capable of bending radially inward or outward with the application of a force. Annular flange  128  can define a chamber  150 . Chamber  150  can encircle interior portion  142  of proximal portion  124 . Chamber  150  can be configured and arranged to receive biasing member  152 . Biasing member  152  has at least one outwardly biased member. In some embodiments, biasing member  152  has more than one outwardly biased member. When seated within chamber  150 , biasing member  152  applies an outward force against annular flange  128 , biasing annular flange  128  outward against introducer  116 . When proximal portion  124  is within introducer  116 , proximal portion  124  is in a contracted position with its outer diameter substantially the same as the outer diameter of retaining sleeve  130 . In some embodiments (not shown in  FIG. 5 ), annular flange  128  connects with the proximal end of interior support  142  to completely surround biasing member  152 . 
         [0041]      FIG. 6  illustrates distal tip assembly  104 , retaining sleeve  130 , and introducer  116  according to an embodiment. The outward biased member(s) of biasing member  152  (not shown) apply an outward force to annular flange  128  (not shown). Accordingly, when proximal portion  124  extends past introducer  116 , biasing member  152  causes proximal portion  124  to expand such that its outer diameter is larger than the outer diameter of retaining sleeve  130 . 
         [0042]      FIG. 7  depicts biasing member  152  according to an embodiment. Biasing member  152  can be a spring. In one embodiment, biasing member  152  includes a pair of annular rings  154 . The outwardly biased member(s) of biasing member  152  can include a plurality of spaced apart leaflets  156  running between the pairs of annular rings  154 . Leaflets  156  are biased outward, for example, the center portions of leaflets  156  arc radially outward from annular rings  154 . In one embodiment, biasing member  152  can be made of any suitable shape memory material, for example, nitinol. The shape memory material can create the outward bias of leaflets  156  at a certain temperatures, for example, the temperature of blood within the body. In some embodiments, biasing member  152  can be made from other suitable materials, for example, any suitable metal or plastic. In other embodiments, leaflets  156  can have stress concentrations that create the outward bias of biasing member  152 . 
         [0043]      FIG. 8  depicts a cross-sectional view of distal tip assembly  104  including biasing member  152  as shown in  FIG. 7  according to an embodiment. Biasing member  152  is seated within chamber  150  defined by annular flange  128 . As shown in  FIG. 8 , proximal portion  124  is in an expanded position having an outer diameter greater than the outer diameter of retaining sleeve  130 . Proximal portion  124  is adjacent the retaining sleeve  130 . Accordingly, the larger diameter of proximal portion  124  provides an atraumatic cushion for the distal edge of retaining sleeve  130  during delivery. 
         [0044]    In some embodiments, as shown in  FIGS. 5 and 8 , biasing member  152  is coupled directly to only interior portion  142  extending proximally from distal portion  122 . For example, both annular rings  154  of biasing member  152  are adjacent interior portion  142 . 
         [0045]    In other embodiments, for example, as shown in  FIGS. 9 and 10  that illustrate cross-sectional views of distal tip assembly  104  according to an embodiment, a proximal portion of biasing member  152  is coupled directly to intermediate shaft  132 , and a distal portion of biasing member  152  is coupled to distal portion  122  and/or interior portion  142 . For example, the proximal annular ring  154  is adjacent intermediate shaft  132 , and the distal annular ring  154  is adjacent interior portion  142  extending proximally from distal portion  122 . Accordingly, adding compression or tension to intermediate shaft  132  can control movement of biasing member  152 . Particularly, as intermediate shaft  132  is advanced distally relative to distal portion  122  and interior portion  142 , the proximal annular ring  154  attached to intermediate shaft  132  moves distally, causing leaflets  156  to deflect radially outward because the distal annular ring  154  remains stationary relative to distal portion  122  and interior portion  142 . As intermediate shaft  132  is advanced proximally relative to distal portion  122  and interior portion  142 , the proximal annular ring  154  attached to intermediate shaft  132  moves proximally, causing leaflets  156  to flatten because the distal annular ring  154  remains stationary relative to distal portion  122  and interior portion  142 . 
         [0046]      FIG. 11  is a cross-sectional view of distal tip assembly  104  and retaining sleeve  130  according to an embodiment. As shown in  FIG. 11 , the profile of proximal portion  124  in the expanded position is tapered with the outer diameter of proximal portion  124  increasing as proximal portion  124  extends proximally. Thus, the proximal edge of proximal portion  124  has the largest outer diameter. Annular flange  128 , and in some embodiments a portion of distal portion  122 , can have an over-molded biasing member  152 —biasing member  152  is encased by proximal portion  124 . Biasing member  152  can having one or more outwardly biased members that cause annular flange  128  of proximal portion  124  to flare radially outward, giving proximal portion  124  a larger diameter than the outer diameter of retaining sleeve  130 . 
         [0047]      FIGS. 12 and 13  illustrate proximal portion  124  in a contracted position and in an expanded position, respectively, according to an embodiment. Biasing member  152  includes annular ring  158  and a plurality of spaced apart tabs  160  that extend proximally from annular ring  158 . Tabs  160  are biased outward, causing flange  128  to flare outward as seen in  FIG. 13 . Annular ring  158  can be over-molded within proximal portion  124  or both the proximal portion  124  and distal portion  122 . 
         [0048]    In another embodiment (not shown), annular flange  128  can have a preformed profile having an outer diameter of proximal portion  124  that is larger than the outer diameter of retaining sleeve  130 . Accordingly, annular flange  128  can be in the expanded position without biasing member  152 . 
         [0049]    A method of implanting a prosthesis, for example, a heart valve prosthesis, using a catheter according to an embodiment includes inserting distal tip assembly  104  into a body lumen or cavity, for example, the femoral artery, the aorta, the subclavian artery, the brachial artery, or into a chamber of the heart, for example, the ventricle via a patient&#39;s heart apex, as is known in the art. Once within the body lumen or cavity, the proximal portion  124  can be expanded to the expanded position having an outer diameter greater than the outer diameter of retaining sleeve  130 . The expanded position of proximal portion  124  creates an atraumatic cushion between the wall of the body lumen and the distal edge of retaining sleeve  130 . In the expanded condition, proximal portion  124  will contact the wall of the body lumen or cavity before the distal, leading edge of retaining sleeve  130 , which will deflect the leading edge of the retaining sleeve away from the wall, In one embodiment, the proximal portion  124  assumes the expanded position automatically once distal tip assembly  104  passes through introducer  116 , for example, when proximal portion  124  includes biasing member  152 . In another embodiment, proximal portion  124  is selectively expanded to the expanded position, for example, by increasing the pressure in cavity  140  defined by balloon element  126 , or in another embodiment by applying compression or tension to intermediate shaft  132  that is connected to a proximal portion of biasing member  152 , deflecting biasing member  152 . 
         [0050]    After expanding proximal portion  124 , distal tip assembly  104  can be advanced to a desired target site. The atraumatic cushion created by the proximal portion  124  in the expanded position reduces the risk of damage to the walls of the body lumen or cavity during advancement, particularly, advancement through a bend. At the target site, prosthesis  200 , for example, ahead valve prosthesis, is released from the delivery catheter  100 , for example, by moving distal tip assembly  104  and retaining sleeve  130  to the open configuration. In some embodiments, a user rotates the knobs of handle assembly  102  to move distal tip assembly  104  distally relative to retaining sleeve  130  to release prosthesis  200 . Prosthesis  200  can then expand against the body lumen or cavity wall to secure prosthesis  200  in place. 
         [0051]    After deployment of prosthesis  200 , distal tip assembly  104  and introducer  116  can be removed from the body lumen or cavity. In one embodiment, proximal portion  124  is selectively reduced to the contracted position. For example, proximal portion  124  can be selectively reduced by decreasing the pressure within cavity  140  defined by balloon element  126 , or by deflecting biasing member  152  through the application of compression or tension to intermediate shaft  132  attached to biasing member  152 . Distal tip assembly  104  is then pulled back through prosthesis  200 . Distal tip assembly  104  can be withdrawn into introducer  116 . The introducer  116  and distal tip assembly  104  are then withdrawn from the body lumen or cavity. In another embodiment, proximal portion  124  is reduced to the contracted position when proximal portion is pulled back through introducer  116 . 
         [0052]    In some embodiments, prosthesis  200  can be a heart valve prosthesis delivered, for example, through a transapical approach, a subclavian approach, a transfemoral approach, and a brachial approach. Components and methods according to embodiments of the present invention can be used in conjunction with catheters designed for alternate approaches. 
         [0053]    The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. 
         [0054]    It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to he interpreted by the skilled artisan in light of the teachings and guidance. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.