as used herein , the terms “ proximal ” and “ distal ” are to be taken as relative to a user using the disclosed delivery devices . “ proximal ” is to be understood as relatively close to the user and “ distal ” is to be understood as relatively farther away from the user . referring to fig1 , an exemplary transapical delivery device 110 for a collapsible prosthetic heart valve ( or other types of self - expanding collapsible stents ) has a catheter assembly 116 for delivering the heart valve to and deploying the heart valve at a target location , and an operating handle 120 for controlling deployment of the valve from the catheter assembly . the delivery device 110 extends from a proximal end 112 to a distal tip 114 . the catheter assembly 116 is adapted to receive a collapsible prosthetic heart valve ( not shown ) in a compartment 123 defined around a tubular support shaft 121 and covered by a distal sheath 124 . the support shaft 121 extends between a pair of spaced retainers 125 and 127 affixed thereto and defining the ends of the compartment 123 . a collapsible prosthetic valve may be assembled around the support shaft 121 and between the retainers 125 and 127 in the compartment 123 . the distal sheath 124 surrounds the support shaft 121 and is slidable relative to the support shaft such that it can selectively cover or uncover the compartment 123 . the distal sheath 124 is affixed at its distal end to the distal tip 114 , and its proximal end 129 abuts the retainer 127 when the distal sheath is fully covering the compartment 123 , as shown in fig1 . the proximal end 129 of the distal sheath 124 is spaced apart from the retainer 127 when the compartment 123 is at least partially uncovered . the delivery device further includes an outer shaft 122 , the proximal end of which is connected to the operating handle 120 , and the distal end of which is connected to the retainer 127 . an inner shaft 126 extends through the operating handle 120 and the support shaft 121 to the distal tip 114 . the connection of the distal sheath 124 to the distal tip 114 thus enables the inner shaft 126 to control the movement of the distal sheath both proximally and distally . the operating handle 120 is adapted to control deployment of a prosthetic valve located in the compartment 123 by permitting a user to selectively slide the inner shaft 126 and the attached distal sheath 124 distally or proximally relative to the support shaft 121 , thereby respectively uncovering or covering the compartment with the distal sheath . the operating handle 120 may include a resheathing lock mechanism for preventing the user from accidentally completing the deployment of a valve located in the compartment 123 . details of the operating handle is described in u . s . provisional patent ser . no . 61 / 665 , 527 , filed jun . 28 , 2012 , the content of which is hereby incorporated by reference in its entirety . fig2 is a cross - sectional view of a conventional distal sheath connection having pins . distal sheath 124 may be attached to nosecone insert 140 through one or more radially extending pins 190 . nosecone insert 140 may be attached to inner shaft 126 by laser welds 142 . pins 190 create a low strength connection between distal sheath 124 and nosecone insert 140 and are difficult to manufacture . in addition , pins 190 may unnecessarily increase the outer diameter of the distal end of the device . such pins 190 may be trimmed so as to form a flush surface with the distal sheath 124 . pins 190 may further require the use of adhesive 195 to protect the patient from sharp edges . fig3 is an enlarged perspective view of a distal sheath 124 and inner shaft 126 of the delivery device of fig1 attached to one another using a connector 200 . for the sake of clarity , tip 114 is shown in phantom lines to expose the connector . distal sheath connector 200 forms a durable attachment between distal sheath 124 and inner shaft 126 , while maintaining a small diameter and eliminating the need for adhesive to protect the patient from sharp edges as shown in fig2 . the components of distal sheath connector 200 will be described in more detail with reference to fig4 a , 4b and 5a - c . fig4 a and 4b are side and cross - sectional views of a wedge 300 of a distal sheath connector 200 . wedge 300 may be formed of stainless steel or any other suitable metal such as titanium , nitinol , platinum , tantalum , gold , silver , cobalt - chromium . alternatively , wedge 300 may be formed of any suitable biocompatible material including certain plastics and polymers . wedge 300 forms the first component of distal sheath connector 200 and sits inside a ring as will be described in further detail below . wedge 300 may be formed of a substantially cylindrical body having a cone portion 340 , and a lumen 330 extending therethrough between a first end 310 and a second end 320 . lumen 330 may be sized to receive inner shaft 126 . as seen in fig4 a , cone portion 340 may include a series of annular steps 350 such that the outer diameter of the wedge 300 increases from the first end 310 to the second end 320 . annular steps may allow for better attachment to distal sheath 124 . fig5 a and 5b are side and cross - sectional views of a ring 400 of distal sheath connector 200 . ring 400 may be formed of stainless steel or other suitable metals such as those used for wedge 300 . ring 400 and wedge 300 may be formed of the same material . ring 400 includes a first end 410 , a second end 420 and a lumen 430 extending therethrough . lumen 430 widens to form a taper 450 near second end 420 to complement steps 350 of wedge 300 as will be appreciated from the assembled connector . as shown in fig5 c , instead of a taper 450 , ring 400 may include a series of concentric recesses 455 sized and shaped to complement annular steps 350 of wedge 300 . fig6 is a cross - sectional view of the distal sheath , inner shaft and distal sheath connector disposed in a pneumatic cylinder during assembly . wedge 300 may be first mounted on inner shaft 126 and welded to the inner shaft at position w 1 . this welding may be accomplished using a laser welder . in addition , an end portion t of distal sheath 124 may be thermoformed or tapered inwardly as seen in fig6 using a tipping machine ( not shown ). wedge 300 and inner shaft 126 may be slid into distal sheath 124 through the non - tapered end of the sheath until the steps 350 of the wedge contact the tapered portion t of the sheath . ring 400 may then be assembled over wedge 300 with tapered portion t of distal sheath 124 disposed therebetween . a pneumatic cylinder may be used to clamp wedge 300 , ring 400 and distal sheath 124 together . an exemplary embodiment of pneumatic cylinder 500 includes a first plate p 1 and a second plate p 2 that apply force to the assembly in the directions shown by arrows a . plates p 1 and p 2 move toward one another forcing wedge 300 into and through ring 400 so that the annular steps 350 engage with at least one of concentric recesses 455 of ring 400 and distal sheath 124 . thus , plates p 1 and p 2 may hold wedge 300 and ring 400 of the connector in place , with the distal sheath partially sandwiched in between . a final weld w 2 may be circumferentially made between wedge 300 and ring 400 to permanently fix the two together . in some examples , welds w 1 and w 2 may be laser welds . though the preceding example illustrates joining the wedge and ring using welds , it will be understood that any suitable technique for joining the two components may be used including for example , heat staking , impulse sealing , ultrasonic welding , snap fit , press fit , friction welding , vibration welding , hot plate welding and adhesive bonding and may depend on the materials for the wedge and / or ring . fig7 is a cross - sectional view of an assembled distal sheath connector 200 showing distal sheath 124 sandwiched between wedge 300 and ring 400 . using distal sheath connector 200 , distal sheath 124 will more reliably attached to inner shaft 126 and be less prone to failure . in operation , handle 120 may be used to deploy a prosthetic valve from the compartment 123 . specifically , the user can rotate the deployment actuator 121 to push the distal sheath 124 distally relative to the compartment 123 and expose and initiate deployment of the valve located therein . once the valve has been properly positioned , the deployment operation may be completed to release the valve from compartment 123 . the operating handles described herein may be provided with a deployment locking mechanism . such a deployment locking mechanism may prevent the accidental initiation of deployment by fixing the carriage assembly to the frame while the lock is in a locked position . moreover , the operating handle may include a resheathing lock , or a number of resheathing locks , with or without a deployment lock , resulting in any number of stages in the deployment process . for example , there may be two , three , four , five , six or more resheathing locks , which thus enable the deployment procedure to be controlled incrementally . such deployment locks and resheathing locks may have a structure similar to those shown and described in co - pending u . s . patent application ser . no . 13 / 212 , 442 , filed on aug . 18 , 2011 , the content of which is hereby incorporated by reference herein in its entirety . although the invention herein has been described with reference to particular embodiments , it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention . it is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims . it will be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims . it will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments .
a connector for coupling a distal sheath to an inner shaft of a medical delivery device includes a wedge defining a lumen for accepting the inner shaft of the medical delivery device and a cylindrical ring sized to mate with the wedge . the wedge may be welded or otherwise fixed to the inner shaft . the wedge and the ring are configured to be pressed together and lock a portion of the distal sheath therebetween .