lumens 34 contain the valve retention cables 40 and the lumens 36 contain the positioning mechanisms 60 in this embodiment the pusher catheter 30 may continue to be advanced even if the positioning mechanisms 60 can no longer be advanced in one embodiment the positioning mechanisms are small enough to fit three valve retention mechanisms and an associated containment sheath in a single lumen 36 leaving two other lumens 36 unused or available for use as irrigation channels the releasable grasping mechanisms 50 may be similar to those shown and described in u s pat pub 2008 0082165 at fig5 8 another embodiment of releasable grasping mechanisms is shown in fig3 and 4 the grasping mechanisms 50 are attached to commissural points on an implant 1 when the device 10 is loaded the grasping mechanism 50 provide the ability to retract the implant back into the device 10 in the event that the physician feels doing so is appropriate fig3 shows a grasping mechanism 50 in an open configuration the grasping mechanism 50 includes a hook 52 that slides within a mouth 54 the hook 52 defines a recess 56 sized to accommodate a component such as a commissural point or a braid of the tool or implant 1 the mouth 54 defines a slot 58 that is also sized to accommodate the component fig4 shows that when the grasping mechanism 50 is in a closed configuration the recess 56 and the slot 58 together define a passage 59 that traps the component therein the grasping mechanism 50 is attached to.