Abstract:
A steerable catheter or sheath includes a catheter or sheath body defining a longitudinal axis; first and second actuation wires extending from a proximal end of the body; and a control handle coupled to the body for steering a distal end of the body. The control handle includes a grip portion including a pivot; a wire diverting assembly located on the grip portion at a location separate from the pivot; and an actuator assembly coupled to the pivot and configured for pivotal movement in a single plane. The wire diverting assembly can include first and second actuation wire connection locations that are disposed on opposite sides of the longitudinal axis. The first and second actuation wires can extend toward the wire diverting assembly in a first orientation, and the wire diverting assembly can change the first orientation to a second orientation that is at an angle to the first orientation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/542,361, filed Aug. 17, 2009 (the &#39;361 application), now pending, which is a continuation of U.S. application Ser. No. 11/115,600, filed 26 Apr. 2005 (the &#39;600 application), which is now U.S. Pat. No. 7,591,784. The &#39;361 application and the &#39;600 application are both hereby incorporated by reference as though fully set forth herein 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    a. Field of the Invention 
         [0003]    The present invention relates to catheters and sheaths and methods of using catheters and sheaths. More particularly, the present invention relates to steerable catheter or sheath control handles and methods of manufacturing and using such handles. 
         [0004]    b. Background Art 
         [0005]    Catheters having conductive electrodes along a distal end are commonly used for intra-cardiac electrophysiology studies. The distal portion of such a catheter is typically placed into the heart to monitor and/or record the intra-cardiac electrical signals during electrophysiology studies or during intra-cardiac mapping. The orientation or configuration of the catheter distal end is controlled via an actuator located on a handle outside of the body, and the electrodes conduct cardiac electrical signals to appropriate monitoring and recording devices that are operatively connected at the handle of the catheter. 
         [0006]    Typically, these catheters include a generally cylindrical electrically non-conductive body. The main body includes a flexible tube constructed from polyurethane, nylon or other electrically non-conductive flexible material. The main body further includes braided steel wires or other non-metallic fibers in its wall as reinforcing elements. Each electrode has a relatively fine electrically conductive wire attached thereto and extending through the main body of the catheter. The conductive wire extends from the distal end to a proximal end where electrical connectors such as plugs or jacks are provided to be plugged into a corresponding socket provided in a recording or monitoring device. 
         [0007]    The distal portion of the main body is selectively deformed into a variety of curved configurations using the actuator. The actuator is commonly internally linked to the distal portion of the catheter by at least one actuation wire. Some catheters employ a single actuation wire, which is pulled (i.e., placed in tension) by the actuator in order to cause the distal portion of the main body to deform. Other catheters have at least two actuation wires, where the actuation of one wire (i.e., placing one wire in tension) results in the other wire going slack (i.e., the wire does not carry a compressive load). In such catheters, where the actuation wires are not adapted to carry compressive loads (i.e., the actuation wires are only meant to be placed in tension), the actuation wires are commonly called pull or tension wires. 
         [0008]    To deform the distal end of the catheter into a variety of configurations, a more recent catheter design employs a pair of actuation wires that are adapted such that one of the actuation wires carries a compressive force when the other actuation wire carries a tensile force. In such catheters, where the actuation wires are adapted to carry both compressive and tension loads, the actuation wires are commonly called push/pull or tension/compression wires and the corresponding catheter actuators are called push-pull actuators. U.S. Pat. No. 5,861,024 to Rashidi, which issued Jan. 19, 1999, is representative of a push-pull actuator of this type, and the details thereof are incorporated herein by reference. 
         [0009]    While many of the existing catheter actuators provide precise operation and good flexibility in movement of the distal portion of the body, the existing actuators often offer a range of distal portion displacement that is less than desirable. In other words, the amount of push/pull of the actuation wires (i.e., the steering travel) is often inadequate for the medical procedure being performed. The inadequacy of the steering travel typically results from the generally limited size of the actuator body, which is usually sized for receipt and manipulation between the thumb and index finger of a user&#39;s hand. Accordingly, a need exists to provide an improved actuating assembly for a catheter that increases the amount of steering travel associated with the actuator. 
       BRIEF SUMMARY OF INVENTION 
       [0010]    In accordance with an embodiment of the disclosure, a steerable catheter or sheath can comprise a catheter or sheath body defining a longitudinal axis; first and second actuation wires extending from a proximal end of the body; and a control handle coupled to the body for steering a distal end of the body. The control handle can comprise a grip portion including a pivot; a wire diverting assembly located on the grip portion at a location separate from the pivot; and an actuator assembly pivotally coupled to the pivot and configured for pivotal movement in a single plane. The wire diverting assembly can comprise first and second actuation wire connection locations that are disposed on opposite sides of the longitudinal axis. The first and second actuation wires can extend toward the wire diverting assembly in a first orientation and the wire diverting assembly can change the first orientation to a second orientation that is at an angle to the first orientation and divert the first and second actuation wires respectively to the first and second actuation wire connection locations. 
         [0011]    In accordance with some embodiments of the disclosure, at least a portion of each of the first and second actuation wires comprises a generally circular cross section. In accordance with some embodiments of the disclosure, at least a portion of each of the first and second actuation wires comprises a generally flat cross-section. In accordance with some embodiments of the disclosure, at least a first portion of each of the first and second actuation wires comprises a generally circular cross-section, and at least a second portion of each of the first and second actuation wires comprises a generally flat cross-section. In accordance with some embodiments of the disclosure, at least one of the first and second actuation wires is formed of super elastic Nitinol. In accordance with some embodiments of the disclosure, at least a portion of at least one of the first and second actuation wires is formed of a material that permits tension or tension and compression. 
         [0012]    In accordance with some embodiments of the disclosure, the grip portion comprises a first grip portion including a first surface from which the pivot extends; and a second grip portion mated with the first grip portion. The second grip portion can include a second surface. The actuator can further comprise a slot. The wire diverting assembly can further comprise a portion that is configured to extend into the slot. The wire diverting assembly can further comprise first and second bearings respectively positioned on first and second opposite sides of the longitudinal axis. The bearings can be annulus shaped. The first and second actuation wires respectively can divert about the first and second bearings. The wire diverting assembly can further comprise a separating assembly for separating the actuation wires into separate planes, and the bearings can be on opposite sides of the separating assembly from each other. The actuation wires can cross the longitudinal axis as they extend from their respective bearings to their respective actuation wire connection locations. 
         [0013]    In accordance with some embodiments of the disclosure, a control handle for a steerable catheter or sheath can comprise a grip portion including a pivot, the grip portion extending along a longitudinal axis. The control handle can further comprise a wire diverting assembly located on the grip portion at a location separate from the pivot. The wire diverting assembly can comprise first and second actuation wire connection locations that are disposed on opposite sides of the longitudinal axis. The control handle can further comprise an actuator assembly pivotally coupled to the pivot and configured for pivotal movement in a single plane. The wire diverting assembly can be configured to change an orientation of first and second actuation wires from a first orientation in which the first and second actuation wires are extending toward the wire diverting assembly to a second orientation that is at an angle to the first orientation. The wire diverting assembly can also be configured to divert the first and second actuation wires respectively to the first and second actuation wire connection locations. 
         [0014]    The grip portion can comprise a first grip portion including a first surface from which the pivot extends; and a second grip portion mated with the first grip portion. The second grip portion can include a second surface. The actuator can further comprise a slot. The wire diverting assembly can further include a portion that is configured to extend into the slot. The wire diverting assembly can further comprise first and second bearings respectively positioned on first and second opposite sides of the longitudinal axis. The bearings can be annulus shaped. The wire diverting assembly can further comprise a separating assembly configured to separate the actuation wires into separate planes. The bearings can be on opposite sides of the separating assembly from each other. 
         [0015]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of the catheter or sheath of the present invention with portions of the catheter&#39;s cylindrical hollow body broken away to show internal components of the body. 
           [0017]      FIG. 2  is a perspective view of the actuator handle wherein the upper grip portion has been removed to reveal the actuation mechanism. 
           [0018]      FIG. 3  is the same view of the handle depicted in  FIG. 2 , except the actuator has been removed to more fully illustrate the rest of the actuation mechanism. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 1  is a perspective view of the catheter or sheath  10  of the present invention with portions of the catheter&#39;s elongated flexible generally cylindrical hollow body  12  broken away to show internal components of the body  12 . As shown in  FIG. 1 , in one embodiment, the catheter  10 , which is an electrophysiology, RF ablation, or similar catheter  10 , includes an elongated flexible generally cylindrical hollow body  12  and an actuation handle  14  coupled to a proximal end  15  of the body  12 . As will be understood from the following discussion, the catheter  10  is advantageous in that the actuation handle  14  is configured to significantly increase the steering travel of the distal end  16  of the body  12 , as compared to prior art actuation handles. 
         [0020]    In one embodiment, the body  12  is typically polyurethane, nylon or any suitable electrically non-conductive material. The body  12  serves as at least a portion of the blood-contacting segment of the catheter  10  and is vascularly inserted into a patient by methods and means well known in the art. 
         [0021]    As illustrated in  FIG. 1 , the distal end  16  of the body  12  includes plural spaced electrodes  18 . Each electrode  18  is connected to a fine electrical conductor wire that extends through the body  12  and the handle  14 . An electrical plug extends from the proximal end of the handle  14  and is adapted to be inserted into a recording, monitoring, or RF ablation device. 
         [0022]    As indicated in  FIG. 1 , the body  1 - 2  includes actuation wires  20 ,  22  that extend longitudinally in a side-by side relationship through the body  12  and into the handle  14 . The handle  14  is used to displace the actuation wires  20 ,  22  to manipulate the distal end  16  of the body  12  into a variety of configurations and shapes to perform intravascular testing and ablation procedures. The distal ends of the actuation wires  20 ,  22  are coupled to the distal end  16  of the body  12 , and the proximal end of the actuation wires  20 ,  22  are coupled to the handle&#39;s actuation mechanism. 
         [0023]    In one embodiment, the actuation wires  20 , 22  are formed from a super elastic Nitinol wire or another suitable material. In one embodiment, the actuation wires  20 , 22  have a generally flat cross section, a circular cross section, or a combination of cross-sectional shapes along their length. For example, in one embodiment, the actuation wires  20 ,  22  are generally circular in cross-section along a substantial portion of the wire and have a flattened ribbon-like portion near the distal end  16  of the body  12 . 
         [0024]    In one embodiment, each actuation wire  20 ,  22  resides in a lumen or tube that runs generally the full length of the body  12  and helps to guide the actuation wire  20 ,  22  and prevent the actuation wire  20 ,  22  from buckling. In one embodiment, the actuation wires  20 , 22  are pull or tension wires  20 ,  22  (i.e., the actuation wires  20 ,  22  are not adapted to support a compressive load). In another embodiment, the actuation wires  20 , 22  and the lumens are configured such that the actuation wires  20 ,  22  are pull/push or tension/compression wires  20 ,  22  (i.e., the actuation wires  20 , 22  are adapted to support a compressive load). Thus, when one actuation wire  20 , 22  is placed in tension, the other actuation wire  20 ,  22  will carry a compressive load. This is advantageous because it allows for a decreased number of catheter components and increased deflection control of the distal end  16  of the body  12 . 
         [0025]    As shown in  FIG. 1 , the actuation handle  14  includes a distal end  24  coupled to the proximal end  15  of the body, a proximal end  26 , an upper grip portion  28  coupled to a lower grip portion  30 , and an actuation mechanism that includes an actuator  32  movably mounted to the grip portions  28 ,  30 . As can be understood from  FIG. 1 , an operator can manipulate the distal end  16  of the body  12  by selectively moving the actuator  32  relative to the grip portions  28 ,  30 . 
         [0026]    As illustrated in  FIG. 1 , in one embodiment, the actuation handle  14  has a generally elongated rectangular shape. In other embodiments, the actuation handle  14  will employ other configurations without departing from the scope and intent of the invention. 
         [0027]    For a detailed discussion of the handle&#39;s actuator  32  and its relationship to other portions of the actuation mechanism  34  and the grip portions  28 ,  30 , reference is now made to  FIG. 2 .  FIG. 2  is a perspective view of the actuator handle  14  wherein the upper grip portion  28  has been removed to reveal the actuation mechanism  34 . As shown in  FIG. 2 , in one embodiment, the actuator  32  includes a top plate  36 , a bottom plate  38 , and ribs  40 ,  42  (shown in phantom lines). Each plate  36 ,  38  has an outer planar surface  36   a ,  38   a  and an inner planar surface  36   b ,  38   b.  The actuator  32  is configured such that the inner planar surfaces  36   b ,  38   b  are opposed and generally parallel to each other. 
         [0028]    As illustrated in  FIG. 2 , in one embodiment, the actuator  32  is generally semi-circular in shape such that the actuator  32  has a distal generally linear side or edge  44  and a proximal generally arcuate side or edge  46  that extends between the ends of the generally linear side or edge  44 . As indicated in  FIG. 2 , in one embodiment, each plate  36 ,  38  includes a pivot hole  48 ,  50  that is located near, and centered along, the linear side  44 . In one embodiment, the radius of the arcuate side  46  is generally measured from the center of the pivot holes  48 ,  50 . 
         [0029]    As indicated in  FIG. 2 , the ribs  40 ,  42  are generally perpendicular to, and extend between, the inner planar surfaces  36   b ,  38   b  to interconnect the plates  36 ,  38  to each other to form an integral actuator  32 . As illustrated via phantom lines in  FIG. 2 , in one embodiment, the ribs  40 , 42  extend from their respective ends of the linear side  44  towards the pivot holes  48 ,  50 . The ribs  40 ,  42  are configured such that the actuator may pivot about the pivot holes  48 ,  50  and relative to the grip portions  28 ,  30  without abutting against a wire guide  52  and the actuation wires  20 ,  22 , which pass generally perpendicularly through the axis of the pivot holes  48 ,  50 , as described later in this Detailed Description. For example, as indicated in  FIG. 2  by phantom lines, to provide adequate clearance for actuator pivoting, the ribs  40 ,  42  terminate prior to reaching the pivot holes  48 , 50 . Additionally, the ribs  40 , 42  taper down as they extend towards the pivot holes  48 ,  50  such that the linear sides or edges  44  of each plate  36 ,  38  extend distally past the ribs  40 ,  42  (i.e., the ribs  40 ,  42  are recessed relative to the linear sides or edges  44  of each plate). 
         [0030]    As shown in  FIG. 2 , a slot  53  in the actuator  32  is defined between the inner planar surfaces  36   b ,  38   b.  The slot  53  extends distally from the arcuate side  46  of the actuator  32  towards the ribs  40 ,  42 . As the actuator  32  is pivoted relative to the grip portions  28 ,  30 , the slot  53  allows the upper and lower plates  36 ,  38  to pass over and under, respectively, the actuation wires  20 ,  22 , the wire guide  52 , and the distal ends of a pair of wire dividers  54 ,  56 , as will now be described in the following discussion of  FIG. 3 . 
         [0031]      FIG. 3  is the same view of the handle depicted in  FIG. 2 , except the actuator  32  has been removed to more fully illustrate the rest of the actuation mechanism  34 . As illustrated in  FIG. 3 , in one embodiment, the lower grip portion  30 , which is generally a mirror image of the upper grip portion  28  (i.e., the discussion of the features of the lower grip portion  30  is generally equally applicable to the features of the upper grip portion  28 ), includes a recessed planar area  60  defined between a distal planar area  62  and a proximal planar area  64 . A distal groove  66  extends through the distal planar area  62  along the longitudinal centerline L of the lower grip portion  30 . Similarly, a proximal groove  68  extends through the proximal planar area  64  along the longitudinal centerline L of the lower grip portion  30 . When the upper and lower grip portions  28 ,  30  are mated together to form the handle  14 , the distal and proximal planar areas  62 , 64  of the upper grip portion  28  matingly abut against their respective planar areas  62 ,  64  of the lower grip portion  30 , and the grooves  66 ,  68  in each grip portion  28 ,  30  combine to form a channel, lumen or pathway that, in one embodiment, is coaxial with the longitudinal axis of the handle  14  and extends through the handle  14 . 
         [0032]    For example, as indicated in  FIG. 3 , the distal groove  66  serves as half of the pathway through which the actuation wires  20 , 22 , the central lumen of the body  12  (if any), and the wires leading to the electrodes  18  pass on their way to the proximal end  26  of the handle  14  (the distal groove  66  in the upper grip portion  28  would serve as the other half of said pathway). Likewise, the proximal groove  68  serves as half of the pathway through which the central lumen of the body  12  and the wires leading to the electrodes  18  pass on their way to the proximal end  26  of the handle  14  (the proximal groove  68  in the upper grip portion  28  would serve as the other half of said pathway). 
         [0033]    As shown in  FIG. 3 , a pair of oblique walls  70 ,  72  obliquely converge towards the longitudinal centerline L of the lower grip portion  30  and extend generally perpendicularly upwards from the recessed planar area  60  to the distal planar area  62 . The oblique walls  70 ,  72  serve as an abutment for the linear side or edge  44  of the actuator  32  to prevent the actuator from over pivoting relative to the grip portions  28 ,  30 . In other words, the oblique walls  70 ,  72  serve as mechanical stops to limit movement of the actuator  32  in opposite directions from the actuator&#39;s central undeflected position depicted in  FIGS. 1 and 2 . 
         [0034]    As illustrated in  FIG. 3 , in one embodiment, a pivot  74  extends generally perpendicularly from the recessed planar area  60  in a location that is near the convergence of the oblique walls  70 ,  72 . The pivot  74  is a cylindrical member that is received within the pivot holes  48 ,  50  of the actuator  32  (see  FIG. 2 ) and serves as a pivot about which the actuator  32  may pivot. In one embodiment, the axis of the pivot  74  is centered along the longitudinal centerline L of the lower grip portion  30 , and the pivot  74  includes a pivot groove  76  that is aligned with the longitudinal centerline L in manner similar to that described with respect to the distal and proximal grooves  66 ,  68 . When the upper and lower grip portions  26 ,  38  are matingly joined together, the end planar surface of the upper grip portion&#39;s pivot matingly abuts against the end planar surface of the lower grip portion&#39;s pivot  74 . 
         [0035]    As shown in  FIG. 3 , in one embodiment, a wire guide or tube  52  extends from the distal groove  66  to, and through, the pivot groove  76 . The wire guide  52  serves to maintain the actuation wires  20 ,  22  in an alignment that is generally parallel with the longitudinal centerlines L of the grip portions  36 ,  38 . As illustrated in  FIG. 3 , a space exists between the wire guide  52  and the recessed planar area  60 . Thus, as previously mentioned, the portion of the bottom plate  38  that defines the most proximal edge of the pivot hole  50  may displace through the space between the wire guide  52  and the recessed planar area  60  when the actuator  32  pivots about the pivot  74 . A similar configuration exists between the wire guide  52  and the recessed planar area of the upper grip portion  28  for accommodating the displacement of the portion of the top plate  36  that defines the most proximal edge of the pivot hole  48  when the actuator  32  pivots about the pivot  74 . 
         [0036]    As illustrated in  FIG. 3 , a pair of peripheral walls  78 ,  80  extend from the proximal planar area  64  along the side edges of the proximal portion of the recessed planar area  60 . As indicated in  FIG. 3 , to define a gap  82  (see  FIG. 1 ) between the upper and lower grip portions  28 ,  30  through which the actuator  32  may laterally displace relative to the grips  28 , 30  when the grips  28 ,  30  are mated together, the peripheral walls  78 ,  80  do not extend along the full length of the side edges of the recessed planar area  60 . 
         [0037]    As shown in  FIG. 3 , a pair of bearing assemblies  90 ,  92  are located between the peripheral walls  78 ,  80  in the proximal portion of the recessed planar area  60 . Each bearing assembly  90 ,  92  is positioned on an opposite side of the longitudinal centerline L of the lower grip portion  30 . As illustrated in  FIG. 3 , the bearing assemblies  90 ,  92  serve to divert the actuation wires  20 , 22  from an orientation that is generally parallel to the centerlines L of the grip portions  28 ,  30  to an orientation that is generally non-parallel (e.g., oblique and/or perpendicular) to the centerlines L as the actuation wires  20 ,  22  extend through the distal groove  66 , through the wire guide  52 , about the respective bearing assemblies  90 ,  92  and out to their respective points of connection to the actuator  32 . 
         [0038]    As indicated in  FIG. 3 , each bearing assembly  90 ,  92  includes an upper annulus shaped bearing  94 ,  96  and a lower annulus shaped bearing coaxially rotateably mounted on an axle  98 ,  100  and separated from each other by a wire divider  54 ,  56 . In one embodiment, the axles  98 ,  100  are generally perpendicular to the longitudinal centerline L and the recessed planar area  60 . The upper extreme ends of each axle  98 ,  100  extend upward into receiving holes in the recessed planar area of the upper grip portion  36 . Similarly, the lower extreme ends of each axle  98 ,  100  extend downward into receiving holes in the recessed planar area  60  of the lower grip portion  38 . Thus, each bearing assembly  90 ,  92  with its respective upper bearing  94 ,  96 , lower bearing, and wire divider  54 ,  56  is held in place as an integral unit within the gap  82  defined between the upper and lower grip portions  36 ,  38 . As can be understood from  FIG. 3 , the arrangement of the annulus shaped upper bearings  94 ,  96  and their respective axles  98 ,  100  is a mirror image of the annulus shaped lower bearings and their respective axles  98 ,  100 . 
         [0039]    As illustrated in  FIG. 2 , the bearing assemblies  90 ,  92  are positioned such that the portions of the wire dividers  54 ,  56  that are located distal to the annulus shaped bearings  94 ,  96  extend into the slot  53 , and the annulus shaped bearings  94 ,  96  are located proximal to the arcuate side  46  of the actuator  32 . In other words, in one embodiment, the distal portions of the wire dividers  54 ,  56  extend into the slot  53 . As a result, the top and bottom plates  36 , 38  displace over and under, respectively, the distal portions of the wire dividers  54 ,  56  as the actuator  32  pivots about the pivot  74 . 
         [0040]    As shown in  FIG. 3 , each wire divider  54 ,  56  is elongated and has smooth edges or contoured surfaces to prevent abrasion of the actuation wires  20 ,  22  as they displace against the wire dividers  54 ,  56 . In one embodiment, the wire dividers  54 ,  56  have an elliptical shape with the major axis parallel to the longitudinal centerlines L of the grip portions  36 ,  38 . The wire dividers  54 ,  56  elevationally separate the actuation wires  20 ,  22  into generally parallel planes as the actuation wires  20 ,  22  cross over each other when being diverted about their respective bearing assemblies  90 ,  92 . 
         [0041]    As can be understood from  FIG. 3 , the actuation wires  20 , 22  enter the handle  14  from the body  12  and travel through the distal groove  66  and the wire guide  52  in substantially one plane. The actuation wires  20 ,  22  begin to separate into parallel planes as they proceed towards the wire dividers  54 ,  56 . As the actuation wires  20 ,  22  proceed about the bearing surfaces of the lower and upper bearings  94 ,  96 , the first actuation wire  22  passes against the top surface of the wire dividers  54 ,  56 , and the second actuation wire  20  passes against the bottom surface of the wire dividers  54 ,  56 . 
         [0042]    As indicated in  FIGS. 1-3 , in one embodiment, the actuation wires  20 ,  22  enter the handle  14  from the body  12  and extend through the distal groove  66  and the wire guide  52  in an orientation that is generally parallel to the centerlines L of the grip portions  28 ,  30 . As illustrated in  FIG. 3 , in one embodiment, as the actuation wires  20 ,  22  exit the wire guide  52  on their way to their respective bearing assemblies  90 ,  92 , the actuation wires  20 ,  22  begin to diverge away from each other. Also, as indicated in  FIG. 2 , as the actuation wires  20 ,  22  pass through the wire guide  52  and on to their respective bearing assemblies  90 ,  92 , the actuation wires  20 ,  22  pass through the actuator  32  (i.e., through the slot  53  defined by the top and bottom plates  36 ,  38 ). 
         [0043]    As shown in  FIG. 3 , in one embodiment, a first actuation wire  22  extends from the wire guide  52 , passes over a first wire divider  56 , and first encounters a first upper bearing  96  on the side of the first upper bearing  96  that is on the opposite side of the first upper bearing&#39;s axle  100  from the longitudinal centerline L of the lower grip portion  30 . The first actuation wire  22  then extends about the first upper bearing  96  (thereby changing from an orientation that was generally parallel to the centerline L to an orientation that is non-parallel, e.g., oblique and/or perpendicular, to the centerline L) and passes against the second upper bearing  94  as the first actuation wire  22  passes between the two upper bearings  94 ,  96  on the first actuation wire&#39;s way to its point of connection to the actuator  32 . On the first actuation wire&#39;s way to its point of connection with the actuator  32  (after leaving the second upper bearing  94 ) the first actuation wire  22  again passes through the slot  53  and connects to the actuator  32  near an extreme outer end of a first rib  40  (see  FIG. 2 ). 
         [0044]    As can be understood from  FIG. 3 , in a manner similar to that just described, the second actuation wire  20  extends from the wire guide  52 , passes below the second wire divider  54 , and first encounters a first lower bearing on the side of the first lower bearing that is on the opposite side of the first lower bearing&#39;s axle  98  from the longitudinal centerline L of the lower grip portion  30 . The second actuation wire  20  then extends about the first lower bearing (thereby changing from an orientation that was generally parallel to the centerline L to an orientation that is generally non-parallel, e.g., oblique and/or perpendicular, to the centerline L) and passes against the second lower bearing as the second actuation wire  20  passes between the two lower bearings on the second actuation wire&#39;s way to its point of connection to the actuator  32 . On the second actuation wire&#39;s way to its point of connection with the actuator  32  (after leaving the second lower bearing) the second actuation wire  20  again passes through the slot  53  and connects to the actuator  32  near an extreme outer end of a second rib  42  (see  FIG. 2 ). 
         [0045]    As can be understood from the  FIG. 3  and the immediately preceding description, in one embodiment, each actuation wire  20 ,  22  starts on a first side of the longitudinal centerline L as the actuation wire  20 ,  22  travels along the distal groove  66  and the wire guide  52  on its way to its respective bearing assembly  90 ,  92 . However, once each actuation wire  20 , 22  encounters its respective bearing assembly  90 ,  92 , the actuation wire  20 ,  22  is diverted such that the actuation wire  20 ,  22  passes onto the other side of the longitudinal centerline L. This embodiment is advantageous because it maximizes the extent to which the actuation wires  20 ,  22  can be displaced by the actuator. 
         [0046]    In other embodiments where less actuation is required, the actuation wires  20 , 22  will not pass from one side of the longitudinal centerline L to the other as the actuation wires  20 ,  22  are diverted about their respective bearing assemblies  90 ,  92 . For example, where the first actuation wire  22  is extended between the upper bearings  94 ,  96  prior to routing about the first upper bearing  96 , and the second actuation wire  20  is extended between the lower bearings prior to routing about the first lower bearing, the actuation wires  20 ,  22  will not cross the longitudinal centerline L. 
         [0047]    In use, the body  12  is inserted into the patient in a manner well known in the art. An operator grasps the handle  14  and manipulates the actuator  32  between his thumb and finger. Advantageously, the actuator  32  protrudes from each side of the handle  14  to allow for such ease of movement and manipulation. The actuator  32  is moved relative to the handle  14 , which causes the actuation wires  20 ,  22  to be displaced about the bearing assemblies  90 ,  92 . As a result, the distal portion  16  of the body  12  deflects. 
         [0048]    Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. The invention is limited only by the scope of the following claims.