Patent Publication Number: US-2011066232-A1

Title: Bioprosthetic valve holder  and handle with cutting mechanism and method of using same

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/119,130, filed on Dec. 2, 2008, U.S. patent application Ser. No. 12/422,797, filed on Apr. 13, 2009, which claims priority to U.S. Provisional Patent Application No. 61/044,483, filed on Apr. 12, 2008, and U.S. patent application Ser. No. 12/272,514, filed on Nov. 17, 2008, which claims priority to U.S. Provisional Patent Application No. 60/988,296, filed on Nov. 15, 2007, the entire contents of all these earlier patent applications being hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present invention relates to implements for facilitating minimally invasive surgical procedures, and more particularly for cardiac valve replacement surgery. 
     SUMMARY 
     In some embodiments, the present invention provides a surgical apparatus for use with a prosthetic holder to which a prosthesis is secured by sutures. The apparatus can include an elongated handle having a grip end and a coupler end and defining a first aperture extending along a length from the grip end to the coupler end. The apparatus can also include a first shaft at least partially disposed within the first aperture with a first actuator at the grip end and a holder coupling mechanism at the coupler end. The apparatus can have one of a second shaft and a sheath disposed along the handle with a second actuator at the grip end and a cutting element at the coupler end. A force applied to the first actuator enables one of engagement and disengagement with the prosthesis holder, and a force applied to the second actuator enables deployment of a cutting element to cut the sutures securing the prosthesis to the prosthetic holder. 
     Another embodiment of the invention provides a surgical apparatus for use with a prosthesis including a prosthetic holder having a handle coupling element, the prosthetic holder coupled to a prosthesis by sutures. The apparatus can also include an elongated handle having a grip end and a coupler end, the handle defining a first aperture extending along a length from the grip end to the coupler end, a first shaft at least partially disposed within the first aperture and having a first actuator at the grip end and a holder coupling mechanism at the coupler end, and one of a second shaft and a sheath disposed along the handle and having a second actuator at the grip end and a cutting element at the coupler end. A force applied to the first actuator can enable one of engagement and disengagement of the holder coupling mechanism with the handle coupling element of the prosthesis holder, and a force applied to the second actuator can enable deployment of a cutting element to cut the sutures securing the prosthesis to the prosthetic holder when the prosthesis holder is engaged. 
     Still another embodiment of the present invention provides a method of performing a surgical procedure in which is used a prosthetic holder and an elongated handle having a holder coupling mechanism and a cutting mechanism at a coupler end and a holder coupling actuator and a cutting actuator at a grip end. The method can include tying a prosthesis to the prosthetic holder with sutures, coupling the prosthetic holder to a handle by actuating the holder coupling mechanism, positioning the prosthesis with the grip end of the handle, and decoupling the prosthetic holder from the handle by actuating the holder coupling mechanism. The method can also include suturing the prosthesis to the surrounding tissue, recoupling the prosthetic holder from the handle by actuating the holder coupling mechanism, and cutting the sutures by actuating the cutting mechanism. 
     Other aspects of the present invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side view of a latch type surgical apparatus according to an embodiment of the present invention, shown with the cutter retracted; 
         FIG. 1B  is a cross-sectional side view of the latch type surgical apparatus illustrated in  FIG. 1A , shown with the cutter retracted; 
         FIG. 2A  is a side view of the latch type surgical apparatus of  FIGS. 1A and 1B , shown with the cutter extended; 
         FIG. 2B  is a cross-sectional side view of the latch type surgical apparatus illustrated in  FIGS. 1A-2A , shown with the cutter extended; 
         FIG. 3  is a perspective view of a latch type surgical apparatus according to an embodiment of the present invention, shown disconnected from a socket type prosthetic holder with a valve prosthesis attached; 
         FIG. 4  is a side view of a portion of a latch type surgical apparatus according to an embodiment of the present invention, shown disconnected from a socket type prosthetic holder; 
         FIG. 5A  is a cross-sectional view of a portion of a latch type surgical apparatus according to an embodiment of the present invention, shown connected to a socket type prosthetic holder and with the cutter retracted; 
         FIG. 5B  is a cross-sectional view of the portion of the latch type surgical apparatus illustrated in  FIG. 5A , shown connected to a socket type prosthetic holder and with the cutter extended; 
         FIG. 6  is a perspective view of a socket type prosthetic holder according to an embodiment of the present invention, shown in an open position with a valve prosthesis; 
         FIGS. 7A-7D  are respectively, bottom, side, top, and detailed views of a socket type prosthetic holder according to an embodiment of the present invention, shown in an open position; 
         FIG. 8  is a perspective view of a socket type prosthetic holder according to an embodiment of the present invention, shown in a closed position; 
         FIGS. 8A-8D  are respectively, bottom, side, top, and detailed views of the socket type prosthetic holder illustrated in  FIG. 8 , shown in a closed position; 
         FIG. 9A  is a side view of a socket type surgical apparatus according to an embodiment of the present invention, shown disconnected from a knob type prosthetic holder; 
         FIG. 9B  is cross-sectional side view of the surgical apparatus shown in  FIG. 9A ; 
         FIGS. 9C and 9D  are respectively, a perspective view and a side view of a portion of a socket type surgical apparatus according to an embodiment of the present invention, shown disconnected from a knob type prosthetic holder; 
         FIG. 10  is a perspective view of a knob type prosthetic holder according to an embodiment of the present invention, shown in an open position and with a valve prosthesis; 
         FIGS. 11A-11D  are respectively, bottom perspective, bottom, side, and top views of the knob type prosthetic holder illustrated in  FIG. 10 , shown in an open position; 
         FIGS. 12A-12E  are respectively, bottom perspective, bottom, side, top, and detail views of a knob type prosthetic holder according to an embodiment of the present invention, shown in a closed position; 
         FIG. 13  is a side view of a claw type surgical apparatus according to an embodiment of the present invention, shown disconnected from a knob type prosthetic holder; 
         FIG. 13A  is a cross-sectional view of the surgical apparatus shown in  FIG. 13 , taken at  13 - 13  of  FIG. 13 ; 
         FIG. 14  is a top view of the claw type surgical apparatus shown in  FIGS. 13 and 13A , shown disconnected from a knob type prosthetic holder; 
         FIG. 14A  is a cross-sectional view of the surgical apparatus shown in  FIGS. 13-14 , taken at  14 - 14  of  FIG. 14 ; 
         FIG. 15  is an exploded perspective view of the claw type surgical apparatus shown in  FIGS. 13-14A , shown with a knob type prosthetic holder; 
         FIGS. 16A-16E  are respectively, side, proximal end, distal end, cross-sectional, and perspective views of an outer blade guard of a claw type surgical apparatus according to an embodiment of the present invention; 
         FIGS. 17A-17E  are respectively, side, proximal end, distal end, cross-sectional, and perspective views of a blade mount of a claw type surgical apparatus according to an embodiment of the present invention; 
         FIGS. 18A-18E  are respectively, side, proximal end, distal end, cross-sectional, and perspective views of a blade of a claw type surgical apparatus according to an embodiment of the present invention; 
         FIGS. 19A-19E  are respectively, side, proximal end, distal end, cross-sectional, and perspective views of a claw sleeve of a claw type surgical apparatus according to an embodiment of the present invention; 
         FIGS. 20A-20D  are respectively, side, proximal end, distal end, and perspective views of a grasping claw of a claw type surgical apparatus according to an embodiment of the present invention; 
         FIGS. 21A-21D  are respectively, side, proximal end, cross-sectional, and perspective views of a prosthetic holder according to an embodiment of the present invention and usable with the claw type surgical apparatus of  FIGS. 13-20 ; 
         FIGS. 22A and 22B  are respectively, side and cross-sectional views of a coupler end of a claw type surgical apparatus according to an embodiment of the present invention, shown disconnected from a knob type prosthetic holder; 
         FIGS. 23A and 23B  are respectively, side and cross-sectional views of a coupler end of a claw type surgical apparatus according to an embodiment of the present invention, shown with the claw extended to connect with a knob type prosthetic holder embodiment; 
         FIGS. 24A and 24B  are respectively, side and cross-sectional views of a coupler end of a claw type surgical apparatus according to an embodiment of the present invention, shown connected to a knob type prosthetic holder; 
         FIGS. 25-28  illustrate various valve prosthetics secured to various prosthetic holder embodiments compatible with types of surgical apparatuses disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the present invention are explained in detail, it is to be understood that the present invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The present invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
     The human heart has both bicuspid and tricuspid valves—valves with two and three leaflets, respectively—which regulate blood flow through the heart. If either type of heart valve is not functioning properly, it may necessitate replacement with a bioprosthetic valve (e.g., a valve from a human donor cadaver, a porcine valve, or a biomechanical valve element). Alternatively, a ring or band can be implanted to repair a poorly functioning valve. In order to provide superior outcomes for surgical valve replacement or repair (improve heart function, decrease recovery time, etc.), it is important to reduce the invasiveness of the procedure. A surgical apparatus for positioning the replacement valve or repair ring or band remotely through a small incision can reduce trauma to the heart and connecting vessels. While the majority of the description of the present invention that follows refers by example to a replacement valve, the disclosed invention is capable of being used in surgical procedures involving various types of replacement valves and valve repair elements including rings and bands. 
     A valve prosthesis  410  (see, for example,  FIG. 6 ) includes a generally cylindrical base  412  from which leaflets of the valve extend radially inward. An attachment ring  418  is connected around the outer circumference of the base  412  to attach and seal the valve prosthesis  410  to an aortic wall, usually by suturing. Commissure support struts  414  extend axially from the base  412  to maintain the positioning and seal of the prosthesis  410  with respect to surrounding heart tissue, and are elastically deflectable with respect to the base  412 . The elasticity allows the support struts  414  to be deflected radially inward while the prosthesis  410  is being implanted to provide the surgeon with better access to the attachment ring  418  and surrounding heart tissue for suturing. 
     In some embodiments, a surgical apparatus for valve prostheses can consist of a prosthetic holder  430  connected to a longitudinally extending handle  500 . The handle  500  can have a contoured grip  506  at one end (grip end) and a holder coupling mechanism at the opposing end (coupler end). Various embodiments of the handle  500  presented in the figures are discussed in further detail below. 
     As shown in  FIGS. 1A-2B , a shaft  504  can extend through a sleeve  510  of the handle  500 . The end of the holder shaft  504  adjacent the grip end of the handle  500  can include an actuator button  508 . Alternatively, an actuator can be coupled to the shaft  504  and extend through an aperture at any point along or adjacent the grip  506  of the handle  500 . The opposing end of the shaft  504  can include a holder coupling mechanism, which in the embodiment of  FIGS. 1A-5B , comprises a finger  524  with a latch element  526 . The latch element  526 , which can be spring-activated, is received in mating engagement with a handle coupling mechanism of the prosthetic holder  430 . A relief  522  can be positioned along the finger  524  to allow some flexibility of the holder coupling mechanism. 
     The latch element  526  can be activated by the actuator button  508  to engage or disengage the handle coupling mechanism of the holder  430 . In some embodiments, the holder coupling mechanism can be actuated to provide movement of the prosthetic holder  430  with respect to the handle  500  into configurations shown in  FIGS. 7-8  and  11 - 12 . In some embodiments, two actuators associated with the holder coupling mechanism can be provided—one for each function. Alternatively, a single actuator (as shown in the illustrated embodiments) can be actuated in various ways to provide various functions. For example, a push or pull of the actuator button  508  can enable engagement or disengagement of the handle  500  with the holder  430 , while a twist or rotation of the actuator button  508  can provide relative movement of the holder  430  with respect to the handle  500 , or vise versa. 
     The handle  500  can also include a cutter mechanism  516 , positioned circumferentially around the sleeve  510  over the shaft  504  at the coupler end of the handle  500 . The cutter mechanism  516  can include an actuator  514  positioned adjacent the grip  506 , and a cutter  570  with a blade edge  580  at the opposing end. The cutter  570  can be biased to a retracted position ( FIGS. 1A and 1B ) by a retraction spring  572 . The actuator  514  enables the cutter mechanism  516  to be extended axially ( FIGS. 2A and 2B ) against the spring bias in order to provide the cutting function, which will be discussed in further detail below. A retraction guide  574  positioned at the coupler end of the sleeve  510  can provide guidance for the cutter  570  and a stop for the spring  572 . 
     As shown in  FIGS. 3-6 , a prosthetic holder  430  is designed to provide an interface between the valve prosthesis  410  and the handle  500 . Consequently, the holder  430  includes a handle coupling mechanism which enables selective connection to the holder coupling mechanism of the handle  500 . In the embodiment of  FIGS. 3-8D , the handle coupling mechanism of the prosthetic holder  430  includes a socket  461  contoured to receive the latch element  526  of the handle  500 . The socket  461  is positioned centrally with respect to a branched retraction guide  432 . Each of the branches extends to a reciprocating face  442  and terminates at a retaining face  440 . 
     A support strut  414  of the valve prosthesis can be secured between the reciprocating and retaining faces  442 , 440  of each branch and held in place by sutures  700  as shown in  FIGS. 4-5B ,  7 D, and  8 D. A suture eyelet  452  can be provided on each side of the reciprocating and/or retaining face  442 ,  440  of each branch for the suture  700  to be tied through to anchor the support strut  414 . The reciprocating and retaining faces  442 ,  440  and secured support strut  414  can be retracted radially along the retraction guide  432  from an open position ( FIGS. 7-7D ) to a closed position ( FIGS. 8-8D ). This retraction can be performed by direct manual manipulation of the holder  430  or indirectly by operation of an actuator on the handle  500 , as previously described. The ability to retract the support struts  414  of the valve prosthesis  410  provides a surgeon better access to the attachment ring  418  for suturing the prosthesis  410  to surrounding tissue. 
       FIGS. 9A-9D  illustrate a prosthetic valve holder handle  500  with an alternative type of holder coupler mechanism. Specifically, the latch element  526  of the previous handle embodiment can be replaced with a socket  542 .  FIGS. 10-12E  illustrate an embodiment of the prosthetic holder  430  adapted to selectively connect to the socket type handle embodiment. In this alternative embodiment, the socket  461  of the previous holder embodiment can be replaced with a knob  472 . As shown in  FIGS. 10-12E , the prosthetic holder  430  can alternatively have only one of a reciprocating face  442  and a retaining face  440  for each branch, as the suture eyelets  452  provide sufficient structure to anchor the support strut  414  to the holder  430  with a suture  700 . 
     In another alternative embodiment of the present invention illustrated in  FIGS. 13-15 , an elongated handle  600  can have a contoured grip  606  at one end (grip end) and a holder engaging assembly  602  at an opposing end (coupler end). For discussion purposes, elements of the surgical apparatus of the embodiment illustrated in  FIGS. 13-24B  will be described with “proximal” referring to the location, portion, or perspective closest to the grip end of the handle and “distal” referring to the location, portion, or perspective farthest from the grip end. 
     As shown in  FIGS. 13 and 15 , some embodiments of a handle  600  can be provided with a bend between the grip and coupler ends, which can make the surgical apparatus more ergonomically functional. A first aperture  622  can be defined longitudinally through the handle  600  from the grip end to the coupler end, and a first shaft  604  can be positioned within the first aperture  622 . In some embodiments, the first shaft  604  can be formed of flexible plastic or steel braided cable. A proximal end of the first shaft  604  extending from the grip end can terminate in or be coupled to a first actuator  608 . A distal end of the first shaft  604  can terminate in or be coupled to a holder coupling mechanism  692 . In the illustrated embodiment of  FIGS. 13-24B , the coupling mechanism  692  is a grasping claw. 
     Shown in more detail in  FIGS. 20A-20D , the illustrated grasping claw  692  includes multiple resiliently flexible arms  698  connected at a joint  696 . In some embodiments, the grasping claw  692  can be formed of spring steel or spring polymer. As illustrated in  FIGS. 13A and 14A , the distal end of the first shaft  604  can be connected to the grasping claw  692  at or near the joint  696 . Each arm  698  can include at least one retaining finger  694  at its distal end, which can extend at an angle radially inward from the arm  698 . As illustrated in  FIGS. 22B and 24B , the arms  698  of the grasping claw  692  can be flexed radially inward, reducing the diameter of the claw  692 , in order for it to fit within the holder engaging assembly  602 . When the grasping claw  692  is not retained by the holder engaging assembly  602 , as shown in  FIG. 23B , the arms  698  return to an unflexed state, thereby increasing the diameter of the claw  692 . In the unflexed state, the claw  692  can receive a knob  872  of a prosthetic holder  830 .  FIGS. 22A-24B  illustrate the flexed and unflexed states of the claw  692 , the control of which is explained below. 
     The first aperture  622  can include a wider diameter portion to accommodate a first biasing element  612 , which can abut a flange on the first shaft  604  to bias the shaft in a proximal direction. Consequently, the grasping claw  692  can be maintained within the holder engaging assembly  602  in a closed or retracted state without applying any external force. In order to move the grasping claw  692  out of the holder engagement assembly  602  and return the arms  698  to the unflexed state, a force can be exerted on the first actuator  608  to overcome the bias and move the first shaft  604  distally. A locking mechanism can be associated with the first shaft  604  to prevent unintentional movement of the grasping claw  692 . 
     The grasping claw  692  and the connecting portion of the first shaft  604  are surrounded within the holder engagement assembly  602  by a claw sleeve  684 . As illustrated in  FIGS. 19A-19E , the claw sleeve  684  can include a sheath  688  through which the first shaft  604  extends, and a receptacle  686  sized to receive the grasping claw  692 . Recesses  682  can be defined in the inner surface of the receptacle  686  at the distal end of the claw sleeve  684 . Each recess  682  can be positioned to receive an arm  698  of the grasping claw  692  and guide the opening and closing motion of the claw as it is expelled from or drawn into the holder engagement assembly  602 . 
     A second aperture  618  can be defined longitudinally through the handle  600  from the grip end to the coupler end, and a second shaft  620  can be positioned within the second aperture  618 . In some embodiments, the second shaft  620  can be formed of flexible plastic or steel braided cable. A proximal end of the second shaft  620  extending from the grip end can include or be coupled to a second actuator  628 . A distal end of the second shaft  620  can terminate in or be coupled to a blade mount  672 . The blade mount  672  couples a blade element  680  to the second shaft  620 . 
     As shown in more detail in  FIGS. 17A-17E , the blade mount  672  can be coupled to the second shaft  620  at a connector  670 . The connector  670  can be offset from the central axis of the blade mount  672  in order to accommodate an aperture  674 , which accommodates the claw sleeve  684 . The blade mount  672  can include a blade coupler  676 , which can provide support for and prevent rotation of the blade element  680  with respect to the blade mount  672 . The blade mount  672  can also include posts  678 , the purpose of which will be discussed below. The blade element  680 , shown in detail in  FIGS. 18A-18E , can include a mount coupler  664 , to secure the blade element  680  in place on the blade mount  672  and prevent relative movement between the elements. The blade element  680  further includes a blade edge  662  capable of cutting sutures  700 . 
     A blade guard  650 , illustrated in detail in  FIGS. 16A-16E , can be provided at the distal end of the handle  500 , to protect tissue in the surgical field from the blade element  680 . The blade guard  650  can include an aperture  652  extending from its distal end, which accommodates the blade mount  672  and blade element  680 . The first aperture  622  of the handle  600  can extend from the proximal end of the blade guard  650  and connect to aperture  652 . An arcuate aperture  656  can also extend from the proximal end of the blade guard  650  and connect to aperture  652 . The arcuate aperture  656  can be radially aligned with the second aperture  618  of the handle  600  and the connector  670  of the blade mount  672 . The inner surface of aperture  652  can include a track  658 , which can be positioned to receive the posts  678  of the blade mount  672 . As shown in  FIG. 16D  the track  658  can provide a helical path for the posts  678 . The distal end of the blade guard  650  can include teeth  660  which can engage teeth  832  of a prosthetic holder  830  to prevent rotation of the holder  830  with respect to the handle  600 . 
     The second aperture  618  of the handle  600  can include a wider diameter portion to accommodate a second biasing element  630 , which can abut a flange on the second shaft  620  to bias the second shaft  620  in a proximal direction. Consequently, the blade element  680  can be maintained within the holder engaging assembly  602  in a retracted state without applying any external force. In order to move the blade element  680  out of the holder engagement assembly  602  to engage and cut a suture  700 , a force can be exerted on the second actuator  628  to overcome the bias and move the second shaft  620  distally. A locking mechanism can be associated with the second shaft  620  to prevent unintentional movement of the blade element  680 . 
     When the second shaft  620  is moved distally, the posts  678  of the blade mount  672  follow the helical path of the post tracks  658 , thereby imparting a rotational motion to the blade mount  678  and blade element  680  as they move distally. In this way, the blade element can be deployed from the holder engaging assembly to cut sutures  700  which secure a valve prosthesis to a prosthetic holder  830 . The arcuate aperture  656  of the blade guard  650  enables the second shaft  620  to follow the rotational motion of the blade mount  672  to which it is connected. Alternatively, one or more posts or similar protrusions can be provided within the blade guard  650  to be received in one or more tracks defined by the blade mount  672 . In a further alternative embodiment, the one or more posts and tracks can be provided or defined by the outer surface of the claw sleeve  684  and an inner surface of the blade mount  672 . 
     One embodiment of a prosthetic holder  830  usable with the grasping type handle embodiment  600  is shown in detail in  FIGS. 21A-21D . The holder  830  can include a knob  872  designed to be selectively engaged by the grasping claw  692  and providing an anchor around which sutures  700  can be tied to secure a prosthesis  810  to the holder  830 . A suture channel  836  can be provided at the base of the knob  872  to retain sutures  700  which secure prosthesis  810  to the holder  830 . As previously mentioned, the holder  830  can also include teeth  832  arranged to engage teeth  660  of the blade guard  550  and prevent rotational motion of the holder  830  with respect to the handle  600 . A cutting channel  834  can be positioned radially between the knob  872  and the teeth  832 . The cutting channel  834  can receive the blade edge  662  when the blade element  830  is deployed to cut the sutures  700  that extend across it. 
       FIGS. 25 and 26  illustrate two sample integrations of the prosthetic holder  830  usable with the grasping type handle embodiment  600 . Two types of adapters  900  can enable the holder  830  to be coupled to ring and band prostheses  810 .  FIGS. 27 and 28  show two alternative prosthetic holders  930 ,  430  for use with different types of prostheses, which are also usable with the grasping type handle embodiment  600 . 
     One embodiment of a surgical procedure utilizing the prosthesis holder and handle with cutting mechanism can be performed as follows. A valve prosthesis  810  can secured to a prosthetic holder  830  by sutures  700  tied from the base of the prosthesis to the suture channel  836  around the knob  872 . A force can be applied to the first actuator  608  deploying the grasping claw  692  from the coupler end of the handle  600 . The positioning of the first actuator  608  on the end of the grip  606  can allow a surgeon or surgical assistant to apply this force with a single finger and without necessitating adjustment of the handle  600  within his or her hand. The grasping claw  692  can positioned around the knob  872 , and the force removed from the first actuator  608  causing the grasping claw  692  to engage the knob  872  of the holder  830  as it retracts into the coupling end of the handle  600 . Depending on the type of prosthesis and holder used, a cinching mechanism of the holder  430  can be used to retract support struts  414  and expose the attachment ring  418  (see  FIGS. 7-9  and  10 - 12 ). 
     The valve prosthesis  810 , holder  830 , and holder engaging assembly  602  can be positioned through an incision by the surgeon or assistant using the handle  600 . When the valve is in the desired position, a force can again applied to the first actuator  608  to deploy the grasping claw  692  and release the holder  830  and prosthesis  810 . The handle  600  can then be removed from the surgical site so that the surgeon can suture the valve into place in the heart. After the valve prosthesis  810  is secured, the handle  600  can again be inserted through the incision and the grasping claw  692  deployed via the first actuator  608  to reengage the holder  830 . 
     The surgeon or assistant can cut the sutures  700  tying the prosthesis  810  to the holder  830  by applying a force to the second actuator  628  deploying the blade element  680  from the coupling end. The blade element  680  engages and cuts the sutures  700  as it travels distally into the cutting channel  834  of the holder  830  and rotationally around the claw sleeve  684 , grasping claw  692 , and the knob  872 . The positioning of the second actuator  628  on the grip  606  can allow a surgeon or assistant to apply this force with a single finger and without necessitating adjustment of the handle  600  within his or her hand. The force can be removed from the second actuator  628 , causing the blade element to retract into the holder engagement assembly  602 . The holder  830  can then be withdrawn through the incision and from the surgical site with the handle  600 . 
     Various features and advantages of the invention are set forth in the following claims.