Abstract:
A medical device includes a tissue dissector and a snare loop on a common shaft. At least the distal tip of the snare loop is energizable to function as an electrosurgical element for tissue dissection. In use the snare loop is partially extended from the shaft to expose the electrosurgical element for electrosurgical dissection, and the snare loop is fully extended from the shaft to deploy the snare loop for retrieval and positioning of an implant such as a gastric banding device. The snare loop may be deployed through a pair of jaws also mounted on the shaft for use in tissue dissection.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/469,071, filed May 20, 2009, which is a continuation in part of U.S. application Ser. No. 12/209,586, filed Sep. 12, 2008, which claims the benefit of U.S. Provisional Application No. 60/971,900, filed Sep. 12, 2007. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of systems for performing surgical procedures through minimally invasive access ports. 
       BACKGROUND 
       [0003]    Co-pending U.S. application Ser. No. 12/209,586, filed Sep. 12, 2008 and incorporated herein by reference, describes procedures and devices useful for implanting a gastric banding device (e.g. lap band or Swedish lap band) using a minimally invasive technique. 
         [0004]    In accordance with the of the disclosed implantation procedures, one of more dissection instruments is passed through single port or laparoscopic access devices and used to dissect a tunnel around the posterior side of the stomach, through the fascia/connective tissues surrounding the proximal stomach and lower esophagus. A snare is advanced through the tunnel and positioned with the shaft of the snare device extending through the tunnel and with the loop of the snare accessible from or near the anterior side of the stomach. A portion of the gastric band is passed through the open snare loop and the snare loop is closed to engage the gastric band. Tension is applied to the snare to withdraw the snare back around the posterior side of the stomach and then anteriorly in order to draw the gastric band around the posterior side of the stomach. The gastric band is closed around the stomach. 
         [0005]    The prior application describes a combination dissection and snare device particularly beneficial for carrying out the procedure. That device is disclosed as having an elongate shaft having a pre-curved distal end and an optional dissection balloon positioned on the shaft. A monopolar RF dissection wire is positioned within the shaft and has a conductive tip or electrode extendable from the shaft when needed to electrosurgically dissect or penetrate tissue. A snare loop is also extendable from and retractable into the distal end of the shaft. That device simplifies implantation of a gastric banding device in that it allows the dissection step(s) and the step of engaging the implant to be carried out with a single device. In particular, the device is advanced into the abdominal cavity, and manipulated using RF and/or blunt dissection to form an appropriate path through the connective tissue. As the device is advanced to the posterior side of the stomach, the curvature of the device carries the distal end of the device into a more anterior position. The snare is deployed from the device. The gastric band is passed into the cavity, captured using the snare, and drawn around the posterior side of the stomach using the snare. 
         [0006]    The present application describes an improvement to the combination dissection device and snare disclosed in the prior application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]      FIG. 1  is a perspective view of the electrosurgical dissector and snare device. 
           [0008]      FIG. 2A  is a perspective view of the jaw tip of the device of  FIG. 1 . 
           [0009]      FIG. 2B  is a longitudinal cross-section view of the jaw tip of  FIG. 2 . 
           [0010]      FIG. 3  is a perspective view of the distal end of the device, with the jaw tip removed. 
           [0011]      FIG. 4A  is similar to  FIG. 3  but includes the jaw tip. 
           [0012]      FIG. 4B  is a perspective view of the distal end of the device showing the jaws flexed into the opened position. 
           [0013]      FIG. 5A  is similar to  FIG. 4  but shows the snare fully extended. 
           [0014]      FIG. 5B  is similar to  FIG. 5A  but shows the snare partially extended. 
           [0015]      FIG. 5C  is a close-up view of the partially extended snare. 
           [0016]      FIG. 6  is a perspective view of the snare removed from the snare guide tube and shaft; 
           [0017]      FIG. 7A  is a partially exploded view of the handle in which one shell section of the handle housing is not shown. 
           [0018]      FIG. 7B  is a side elevation of the contents of the handle without the housing. 
           [0019]      FIG. 8  is similar to  FIG. 7B  but shows one shell section of the housing. 
           [0020]      FIGS. 9A-9G  are a sequence of drawings schematically illustrating use of the device for implantation of a gastric banding device. 
       
    
    
     DETAILED DESCRIPTION  
       [0021]      FIG. 1  shows an embodiment of a combination electrosurgical dissector and snare device  10 . Dissector and snare device  10  has a handle  12  and an elongate shaft  14  having a pre-curved distal section  15 . The shaft is preferably rigid or semi-rigid so as to allow it to approximately retain its shape during use, although in alternative embodiment flexible shafts may be used. 
         [0022]    A jaw tip  16  is positioned at the distal end of the shaft  14 . Referring to  FIG. 2A , in one embodiment, the jaw tip  16  is a tubular element having integrally formed first and second jaw members  18   a,    18   b  extending from a tubular coupling  20 . The single piece construction of the jaw tip biases the jaw members  18   a,    18   b  in the closed position shown in  FIG. 2A . Each jaw member has a pair of teeth  19  extending towards the opposed jaw member. When in the closed position, the jaw members  18   a,    18   b  define a distal gap or passage  22  at their distal ends. 
         [0023]    Referring to  FIG. 2B , the jaw tip  16  includes a cylindrical lumen  24  aligned with the passage  22 . Walls defining the lumen  24  having longitudinally-extending edges  26  between the jaw members  18   a,    18   b.  The edges  26  define a space between the jaw members  18   a,    18   b . Due to the varying contour of the edges  26 , the space has a broad distal section  28   a  and a narrow section  28   b  proximal to the distal section  28   a.    
         [0024]    The distal end of the shaft  14 , with the jaw tip  16  removed, is shown in  FIG. 3 . A snare guide tube  30  extends through the lumen of the shaft  14 . A distal element  32  is positioned at the tip of the guide tube  30  and has an opening  34  aligned with the lumen of the snare guide tube  30 . In the illustrated embodiment, the distal element  32  is a spherical bead, the surface of which, as shown in  FIG. 4A , extends into the broad distal section  28   a  of the space between the jaw members  18   a,    18   b.  The opening  34  in the distal element  32  is aligned with the distal passage  22  defined by the jaws in the closed position. 
         [0025]    Referring to  FIG. 7A  the proximal end of the snare guide tube  30  is coupled to a piston  35  disposed within the handle  12 . As will be discussed in detail below, the piston  35  is longitudinally moveable within the handle to a retracted position to withdraw the snare guide tube  30  and thus its distal element  32  in a proximal direction. When the distal element is moved proximally, it cams the jaws to the open position shown in  FIG. 4B  as it moves from within the broad distal section  28   a  to the narrow section  28   b  of the space defined by the edges  26 . As shown, the jaw members  18   a,    18   b  flex at flex regions  33  when they are moved to the open position. When the distal element is returned to a more distal position within the broad section  28   a,  it moves out of contact with the edges  26 , allowing the spring bias of the jaw members  18   a,    18   b  to return them to the closed position. 
         [0026]    A snare  36  is disposed within the snare guide tube  30 . The snare  36  is formed of a wire strand formed into a loop  38 .  FIG. 5A  shows the snare  36  in a fully deployed position in which the loop  38  is fully extended from the guide tube  30 . A v-shaped tip section  40  is positioned at the distal end of the loop  38 . The snare is advanceable from the fully retracted position shown in  FIG. 4A  in which the snare loop is fully contained within the snare guide tube  30 , to a partially extended position shown in  FIG. 5B  in which the tip section  40  extends from the snare guide tube  30 . When the snare loop is in the partially extended position, the portions of the wire loop just proximal to the “v” may extend in parallel contact with one another as shown in  FIG. 5C . The snare loop is further advanceable to the fully deployed position shown in  FIG. 5A . The snare  36  is formed of an electrically conductive wire so that the tip can function as an RF dissection wire. The snare  36  may be conductive only at the tip  40 , with the remainder of the loop  38  covered by insulative material, or the entire loop  40  (including the tip  40 ) may be conductive. 
         [0027]    As most easily viewed in  FIG. 6 , the snare  36  includes two parallel proximal end sections  42   a,    42   b  of the snare wire. The end sections  42   a,    42   b  are connected to a snare conductor  43  by soldering, using a short piece of tubing  47  to cover and complete the joint. Referring now to  FIGS. 7A and 7B , the snare conductor  43  extends through the snare guide tube  30 , around a pin  44 , and is coupled to a slider  46 . The slider  46  includes first and second pins  48   a,    48   b,  each of which is connected to the snare conductor  43 . As shown in  FIG. 8 , the ends of each pin  48   a,    48   b  are slidably disposed in slots  50  in opposite sides of the handle housing (one side of which is shown). A head  52  on the slider  46  is slidably positioned within slots  53  parallel to the slots  50 . 
         [0028]    An upper-surface of the head includes a sawtooth pattern of ridges  55   a . Corresponding ridges  55   b  are formed in the slots  53  such that the ridges  55   a,    55   b  engage one another to maintain the longitudinal position of the slider  46  within the slots  53 . 
         [0029]    The snare conductor  43  extends from the second pin  48   b  of the slider  46 , around another pin  56  and a series of pulleys  58 ,  60 ,  62  and is coupled to a proximal side of the piston  35 . Pulley  58  is supported by a bracket mounted to a compression spring  66 . The compression spring  66  is seated within a slot  68  ( FIG. 7A ) in the handle  12 . 
         [0030]    The snare conductor  43  is electrically coupled to an energy source such as a monopolar RF source  45  ( FIG. 1 ).  FIG. 7B  shows that in the illustrated embodiment, a conductor  59  is coupled to one of the pins  56  with which the snare conductor  43  is in contact, so that the pin  56  electrically couples the snare conductor  43  to conductor  59 . 
         [0031]    A pair of jaw actuation cables  70  is connected to me piston  35 . The cables  70  extend around a pin and are connected to spool  72  connected to a grip  74 . The spool  72  is pivotally mounted within the handle  12  by a pin  76 . 
         [0032]    Referring again to  FIG. 1 , a preferred handle housing is comprised of shell halves  78   a ,  78   b  which, when assembled, leaved an exposed cutout  80 . The cutout  80  is covered by a cover  82  having flexible end sections  84  that extend into the cutout  80 . The cover  82  includes a button  86  disposed between the end sections  84 . The button  86  is coupled to a standoff  87  ( FIG. 7A ) that extends towards the button  86  from the head  52  of slider  46  ( FIG. 8 ). The sawtooth ridges  55   b  in the handle  12  (described with reference to  FIG. 8 ) contact the head  52  on opposite sides of the standoff  87 . Pressing the button  86  towards the cutout  80  depresses the head  52  to move the ridges  55   a  of the head out of engagement with the ridges  55   b  in the handle. Sliding the button  86  distally after disengaging the ridges  55   a,    55   b  slides the slider  46  distally within the handle. When the button slides  86 , its flexible end sections  84  slide within slots  85  ( FIG. 8 ) in the housing. 
         [0033]    Operation of the device  10  will next be described. A user will typically hold the device with his/her palm against the handle  12 , his/her index finger extending through the grip  74 , and his/her thumb on the button  86 . To open the jaws  18   a,    18   b,  the user squeezes the grip  74  towards the handle  12 , causing the grip  74  and spool  72  to pivot relative to the pin  76  and to thus apply tension to the jaw actuation cables  70 . The actuation cables  70  pull the piston  35  in a proximal direction and in doing so they withdraw the snare guide tube  30  proximally. The distal element  32  on the snare guide tube  30  spreads the jaws apart by camming the jaws into the open position by acting on the edges  26  as described above. Releasing the grip  74  causes the jaws to return to the open position under their own spring bias. 
         [0034]    The features for retracting the snare guide tube  30  to open the jaws and for deploying the snare operate cooperatively to maintain the longitudinal alignment of the snare loop  38  and the snare guide tube  30 . In particular, when the piston  35  is moved proximally to retract the snare guide tube  30 , it pulls the distal end of the snare cable  43  (i.e. the portion anchored to the piston  35  near pulley  62 ) proximally, applying tension to the slider  46  and thus the portion of the snare cable  43  that extends into the snare guide tube  30 , to retract the snare  36  by a corresponding amount. This avoids inadvertent exposure of the snare loop  38  when the jaws are opened. The bracket  64  and spring  66  act as a tensioning system to aid in maintaining the position of the snare loop  38  relative to the jaws  18   a,    18   b.    
         [0035]    To extend the snare loop  38 , the user presses button  86  using his or her thumb. The button  86  presses downwardly against the head  52  of the slider  46 , releasing the engagement between the sawtooth ridges  55   a,    55   b.  Once released, the slider  46  is free to slide longitudinally within the handle. The user advances the button  86  to slide the slider  46  in a distal direction, thus pushing the snare loop  38  from the distal end of the snare guide tube  30 . Because of the passage  22  in the jaw tip, the snare loop  38  can be advanced whether the jaws are closed or open. It should be noted that the jaw tip  16  is preferably formed of material that is not electrically conductive so as to prevent conduction of RF energy from the snare to the jaws. 
         [0036]    The user may advance the snare loop  38  by a first amount to expose only the tip  40  ( FIG. 5B ), of s/he may advance the snare loop  38  by a greater amount to fully deploy the snare ( FIG. 5A ). The user can engage the snare loop  38  in an extended position by releasing pressure against the button  86 , allowing the sawtooth ridges of the head  52  to re-engage with the corresponding ridges in the handle. 
         [0037]    When it is time to retract the snare loop  38 , the user applies downward pressure to the button  86  to disengage the ridges  55   a,    55   b  and s/he then retracts the button  86  proximally to return the slider to its original position. 
         [0038]    In a typical procedure, the device  10  is advanced through a single port or laparoscopic access device into the abdominal cavity and advanced towards the stomach. The snare loop  38  is advanced to the position shown in  FIG. 5B , exposing the tip  40 . The snare loop  38  is energized by activating the RE energy source  45  (e.g. by depressing a foot pedal). The tip  40  is advanced around the posterior side of the stomach, electrosurgically forming a tunnel T through the fascia, connective tissue and/or other tissue posterior to the stomach as shown in  FIG. 9A . The user may begin the electrosurgical step adjacent to the lesser curvature LC of the stomach and continue formation of the tunnel under the stomach to the greater curvature GC, or the electrosurgical step may be at the greater curvature and work towards the lesser curvature. 
         [0039]    The electrosurgically formed tunnel T is expanded using the dissecting jaws  18   a,    18   b  as shown in  FIG. 9B . This step may be performed during the electrosurgical step, with the jaws being opened and closed behind the energized tip  40  as the tip  40  forms the tunnel through the tissue. Alternatively, or in addition to using the jaws during electrosurgical dissection, the distal end of the device may be retracted back through runnel and the used at that time (during retraction and/or subsequent re-advancement of the device within the tunnel) to increase the size of the tunnel using known dissection techniques. Use of the jaws for dissection can involve opening the jaws to separate tissue layers on opposite sides of the jaws 
         [0040]    The curvature of the distal section  15  aids in directing the operative tip around the stomach and into a more anterior position ( FIG. 9C ) appropriate for full deployment of the snare for retrieving the gastric band G. Once the tunnel has been dissected to an appropriate size, the snare is moved to the fully deployed position of  FIG. 5A , and a portion of a gastric banding device is placed within the loop of the snare. The snare is withdrawn somewhat to cinch the loop against the gastric banding device. The device  10  is withdrawn, passing again around the posterior side of the stomach, thus drawing the engaged end of the gastric banding device with it. The banding device is closed into a loop and retained in place using known techniques. The dissector and snare device  10  is removed from the body cavity, leaving the banding device implanted around the stomach. 
         [0041]    It should be recognized that a number of Variations of the above-identified embodiments will be obvious to one of ordinary skill in the art in view of the foregoing description. Accordingly, the invention is not to be limited by those specific embodiments and methods of the present invention shown and described herein. Rather, the scope of the invention is to be defined by the claims and their equivalents. 
         [0042]    Any and all applications referred to herein, including for purposes of priority, are hereby incorporated herein by reference.