Patent Publication Number: US-2021169553-A1

Title: Slidable coupling to connect devices

Description:
PRIORITY CLAIM 
     The present application claims the priority and benefit of U.S. Provisional Patent Application Ser. No. 62/945,825 filed Dec. 9, 2019 and entitled “USER INTERFACE AND LOCK FEATURES FOR POSITIONING MULTIPLE COMPONENTS WITHIN A BODY,” U.S. Provisional Patent Application Ser. No. 62/945,836 filed Dec. 9, 2019 and entitled “HELICAL GUIDE CHANNEL WITH VARIABLE PITCH,” and U.S. Provisional Patent Application Ser. No. 62/945,843 filed Dec. 9, 2019 and entitled “SLIDABLE COUPLING TO CONNECT DEVICES.” 
    
    
     FIELD 
     The present disclosure relates to a user interface and lock features for positioning multiple components within a body. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Inserting and manipulating thin elements within living bodies or other objects allows for ever-improving types of analysis, diagnosis, and treatment of those bodies or objects with minimally invasive techniques. By way of two examples, endoscopic imaging and catherization treatments have enabled evaluation and treatment of numerous internal lesions without invasive surgery. 
     Electrosurgical techniques also provide for minimally invasive therapies by selectively applying electrical current to selected tissues. Electrosurgical techniques involve inserting one or more electrodes through an orifice or a small incision and then extending the one or more electrodes to a desired location within a body of a patient. A radio frequency (“RF”) electric current is then applied to the electrodes to coagulate, ablate, or otherwise treat tissue at that location. Monopolar electrosurgical instruments involve the insertion of one electrode that electrically interacts with a second electrode that is electrically connected to the body of the patient. A bipolar electrosurgical instrument involves the deploying of two electrodes at the location within the body of the patient where treatment is to be administered. 
     Positioning one or two electrodes at the desired location in a patient&#39;s body is an important part of electrosurgical treatments. Moving and holding electrodes in place, particularly when more than one electrode has to be moved or held independently of another electrode, may present a challenge for medical personnel directing the treatment. Further, because positioning one or more electrodes in place may involve following a particular sequence of steps in positioning the electrodes, assisting an operator in properly following the sequence also may be important. 
     SUMMARY 
     Disclosed embodiments include: apparatuses, systems, and methods for controlling the movement of multiple components within a body; apparatuses, systems, and methods for motivating elongated implements using a rotating actuator guided by a helical path of varying pitch; and apparatuses, systems, and methods for coupling a device, such as a user interface for controlling movement of multiple components within a body, to another device. 
     In an illustrative embodiment, an apparatus includes an elongated primary electrode defining a lumen therein, an elongated secondary electrode slidably receivable within the lumen, and a sheath configured to slidably receive the primary electrode therein, where the sheath is further configured to convey the primary electrode and the secondary electrode to a target region. A housing is operably coupled with the sheath and movably mounted to slidably motivate the sheath relative to the target region. A primary actuator is operably coupled with the primary electrode and slidably coupled with the housing to motivate the primary electrode relative to the sheath. A secondary actuator is operably coupled with the secondary electrode and movably coupled with the primary actuator to be slidable with the primary actuator to motivate the secondary electrode in concert with the primary electrode. The secondary actuator is rotatable independently of the primary actuator to travel along a helical path to motivate the secondary electrode to move relative to the target region independently of the primary electrode. 
     In another illustrative embodiment, a system for treating tissue at a target region includes an electrical power source configured to selectively provide electrical power between a first pole and a second pole via a two-pole electrical cable. An electrode control apparatus includes an elongated primary electrode defining a lumen therein, an elongated secondary electrode slidably receivable within the lumen, and a sheath configured to slidably receive the primary electrode therein, where the sheath is further configured to convey the primary electrode and the secondary electrode to a target region. A housing is operably coupled with the sheath and movably mounted to slidably motivate the sheath relative to the target region. A primary actuator is operably coupled with the primary electrode and slidably coupled with the housing to motivate the primary electrode relative to the sheath. A secondary actuator is operably coupled with the secondary electrode and movably coupled with the primary actuator to be slidable with the primary actuator to motivate the secondary electrode in concert with the primary electrode. The secondary actuator is rotatable independently of the primary actuator to travel along a helical path to motivate the secondary electrode to move relative to the target region independently of the primary electrode. 
     In a further illustrative embodiment, a method includes moving a distal end of a sheath that contains a primary electrode and a secondary electrode adjacent to a target region. A primary actuator operably coupled with the primary electrode and a secondary actuator operably coupled to the secondary electrode and movably engaged with the primary actuator are slid to a first position to motivate distal ends of the primary electrode and the secondary electrode relative to the target region. The secondary actuator is rotated relative to the primary actuator to cause the secondary actuator to travel independently of the primary actuator along a helical path to a second position to motivate the distal end of the secondary electrode to move independently of the primary electrode relative to the target region. 
     In an additional illustrative embodiment, an apparatus includes an elongated implement movable along an axis. A rotatable actuator is operably coupled with a proximal end of the implement to motivate the implement to move along the axis in response to rotation of the rotatable actuator. A guide is operably coupled with rotatable actuator, wherein the guide defines a generally helical path around the axis to direct movement of a rotatable actuator, and wherein a pitch of the helical path is varied to reduce a distance of travel of the actuator along the axis per unit of rotation of the actuator. 
     In another additional illustrative embodiment, a system includes an elongated primary electrode defining a lumen therein. An elongated secondary electrode is slidably receivable within the lumen. A sheath is configured to slidably receive the primary electrode therein, the sheath being further configured to convey the primary electrode and the secondary electrode toward a target region. A housing is operably coupled with the sheath and movably mounted to slidably motivate the sheath relative to the target region. A primary actuator is operably coupled with the primary electrode and slidably coupled with the housing to motivate the primary electrode to slide relative to the sheath along an axis. The primary actuator includes a guide defining a generally helical path, wherein a pitch of the helical path is varied to reduce movement of a guide member relative to the axis per unit of rotation of the guide member around the helical path. A secondary actuator is operably coupled with the secondary electrode and rotatably received within the guide of the primary actuator. The secondary actuator supports the guide member that is configured to engage the helical path. The secondary actuator is rotatable relative to the primary actuator to motivate the secondary electrode to move relative to the primary electrode. 
     In a further additional illustrative embodiment, a method includes coupling an elongated implement at a proximal end thereof to an actuator that is movable along an axis. The implement is motivated by rotatably moving the actuator through a generally helical path around the axis, where the helical path has a pitch that is varied to change a distance traveled by the actuator along the axis per unit of rotation of the actuator. 
     In another additional embodiment, a locking body defines an opening with a first section having a first width and a second section having a second width that is smaller than the first width, where the locking body is slidably mountable on one of a first device that supports a first coupling and a second device that supports a second coupling. One of the first and second couplings is configured to support thereon a flange having a flange width that is smaller than the first width and larger than the second width. A slidable mounting mechanism is configured to slidably secure the locking body on one of the first device and the second device. The slidable mounting mechanism is further configured to enable the locking body to slide between an open position, in which the first section is positionable to enable the first coupling to be inserted into the second coupling to form a connection, and a closed position, in which an edge of the locking body around the second section abuts the flange such that the coupling that supports the flange is prevented from being withdrawn from the connection 
     In another additional illustrative embodiment, a system includes an elongated primary electrode defining a lumen therein. An elongated secondary electrode is slidably received within the lumen. A sheath slidably receives the primary electrode and is configured to convey the primary electrode and the secondary electrode toward a target region. A housing is operably coupled with the sheath and is movably mounted to slidably motivate the sheath relative to the target region. A primary actuator is operably coupled with the primary electrode and is movably coupled with the housing to motivate the primary electrode relative to the sheath. A secondary actuator is operably coupled with the second electrode and is movably coupled with the primary actuator, where the secondary actuator is separately movable relative to the primary actuator to motivate the secondary electrode to move relative to the primary electrode. A first coupling is supported by the housing and configured to engage a second coupling supporting a flange having a flange width, where the second coupling extends from a device through which the sheath and the electrodes will be conveyed to the target region. A locking body defines an opening having a first section having a first width larger than the flange width and a second section having a second width that is smaller than the flange width. A slidable mounting mechanism is configured to slidably secure the locking body to the housing. The slidable mounting mechanism is further configured to enable the locking body to slide between an open position, in which the first section is positionable to enable the first coupling to insertably receive the second coupling to form a connection, and a closed position, in which an edge of the locking body around the second section abuts the flange such that the coupling that supports the flange is prevented from being withdrawn from the connection. 
     In a further additional illustrative embodiment, a method includes positioning a locking body into an open position, where the locking body defines an opening with a first section having a first width and a second section having a second width that is smaller than the first width. The locking body is slidably mounted on one of a first device that supports a first coupling and a second device that supports a second coupling. The first section is disposed between the first coupling and the second coupling when the locking body is positioned into the open position. A connection is formed by inserting the first coupling within the second coupling such that one of the first and second couplings supports a flange having a flange width that is smaller than the first width and larger than the second width. The locking body is repositioned into a closed position in which an edge of the locking body around the second section abuts the flange to prevent the flange from being withdrawn from the connection. 
     Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, with emphasis instead being placed upon illustrating the principles of the disclosed embodiments. In the drawings: 
         FIG. 1  is a block diagram in partial schematic form of an illustrative system for treating tissue; 
         FIGS. 2-5  are schematic diagrams of positioning of distal ends of a sheath, primary electrode, and secondary electrode relative to a target region; 
         FIGS. 6A and 7A  are schematic diagrams of moving a sheath actuator to position a sheath relative to the target region; 
         FIGS. 6B and 7B  are schematic diagrams of distal ends of the sheath, a primary electrode, and a secondary electrode relative to the target region corresponding to positions of the sheath actuator of  FIGS. 6A and 7A , respectively; 
         FIG. 8  is a side view of an illustrative sheath actuator and a sheath lock; 
         FIG. 9  is a cutaway view of the sheath actuator and sheath lock of  FIG. 8 ; 
         FIG. 10  is a side view of an embodiment of a user interface for positioning components relative to the target region; 
         FIG. 11  is an exploded view of the user interface of  FIG. 10 ; 
         FIGS. 12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, and 21A  are side views of an embodiment of the user interface of  FIG. 10  being manipulated to position multiple components relative to the target region; 
         FIGS. 12B, 13B, 14B, 15B, 16B, 17B, 18B, 19B, 20B, and 21B  are schematic diagrams of distal ends of the sheath, the primary electrode, and the secondary electrode relative to the target region corresponding to positions of the user interface of  FIGS. 12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, and 21A , respectively; 
         FIG. 22  is a side view of a guide sleeve defining a helical channel of varying pitch for guiding a rotatable actuator; 
         FIG. 23  is a side view of sections of the guide sleeve of  FIG. 22 ; 
         FIGS. 24 and 25  are side views of a wire having different cross-sections along its length; 
         FIG. 26  is a cross-sectional view of the wire of  FIGS. 24 and 25 ; 
         FIG. 27  is an exploded view of a coupler for joining together devices; 
         FIG. 28  is a side view of a locking body of the coupler of  FIG. 27 ; 
         FIG. 29  is a flow diagram of an illustrative method of positioning components using a user interface; 
         FIG. 30  is a flow diagram of an illustrative method of motivating an implement using a rotating actuator guided by a helical path of varying pitch; and 
         FIG. 31  is a flow diagram of an illustrative method of coupling together devices with a slidably-mounted locking body. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely illustrative in nature and is not intended to limit the present disclosure, application, or uses. It will be noted that the first digit of three-digit reference numbers and the first two digits of four-digit reference numbers correspond to the first digit of one-digit figure numbers and the first two digits of two-digit figure numbers, respectively, in which the element first appears. 
     The following description explains, by way of illustration only and not of limitation, various embodiments of user interfaces to position electrodes for electrosurgical apparatuses, as well as systems including such user interfaces and methods of using the same. As will be described in detail below, electrosurgical techniques position first and second electrodes in a target region where electrical treatment, such as ablative treatment, is to be applied. For a specific example, the user interfaces and methods of their use may be used for ablating and/or coagulating tissue, removing lesions, and for performing other medical procedures within a lung. 
     It will be appreciated that various embodiments of user interfaces described herein may help to simplify the process of positioning the electrodes and holding the electrodes in place. As will be described below, various embodiments of the user interface accomplish the selective positioning and locking in place of the electrodes by depressing a release, sliding one actuator, and rotating another. 
     Referring to  FIG. 1 , a system  100  is provided for treating tissue at a target region of a patient (not shown in  FIG. 1 ). The system  100  may be a bipolar or monopolar radio frequency (RF) system, as desired, for treating tissue in a patient. However, various embodiments described herein are configured to position two electrodes at the target region to support implementation of a bipolar treatment system, thereby allowing for electric current to be selectively passed through a particular target region in a patient. Specifically, the system  100  may be employed for coagulation and/or ablation of soft tissue during percutaneous and/or endoscopic surgical procedures, such as, for example, bronchoscopic surgical procedures for partial and/or complete ablation of cancerous and/or noncancerous organ lesions. As will be further described, the tissue is treated by positioning one or more electrodes proximate the tissue to be treated and passing an electrical current through the tissue. 
     In some embodiments, the system  100  includes a user interface  102 , an electrosurgical radio frequency (RF) generator operating as a switchable current source  114 , an infusion pump  116 , and an electrosurgical instrument or device  118 , such as, without limitation, a bronchoscope or any other electrosurgical or endoscopic instrument as desired for a particular application. The user interface  102  may be joined with the electrosurgical apparatus  118  with a coupler  150 . The electrosurgical apparatus  118  may be used to convey electrodes (not shown in  FIG. 1 ) through a sheath  103  where the user interface  102  may be used to manipulate positions of the electrodes at the target region. 
     The user interface  102  electrically communicates with the switchable current source  114  though an electrical conductor  130 . In some embodiments, the electrical conductor  130  is connected to a bipolar outlet  131  on the switchable current source  114  when the system is operated in a bipolar mode. The electrical conductor  130  may be coupled with the outlet  131  using an electrical connector  134  configured to electrically engage the outlet  131 . The electrical conductor  130  may be removably or fixably coupled to the user interface  102 , where a flexible electrical coupling (not shown in  FIG. 1 ) associated with the user interface  102  electrically couples the current to the electrodes, as further described below with reference to  FIG. 11 . In some other embodiments, the system  100  can be operated in a monopolar mode when the electrical conductor  130  is connected to a secondary outlet  133  with an adapter (not shown in  FIG. 1 ). 
     The user interface  102  is further connected to the infusion pump  116  with a tube  132  that facilitates the flow of a conductive fluid, such as saline solution, from the infusion pump  116  to the user interface  101 . As also described below with reference to  FIG. 11 , the user interface  102  may include a flexible fluid coupling (not shown in  FIG. 1 ) that receives the flow of conductive fluid from the infusion pump  116  and delivers the conductive fluid to an interior of a primary electrode where it can be delivered to the target region. 
     The switchable current source  114  may be operated with the use of a foot operated unit  120  electrically connected to the switchable current source  114 . The foot operated unit  120  may include a pedal  122  that directs the switchable current source  114  to apply an electrical current to one or more electrodes to cut, ablate, or otherwise treat tissue and a pedal  124  that instructs the switchable current source  114  to apply a lower electrical current to the one or more electrodes to coagulate tissue. 
     In various embodiments the electrosurgical apparatus  118  includes an insertion tube  119  that permits insertion of the sheath  103  into a body (not shown) through an orifice or an incision. A distal end  105  of the sheath  103  is delivered to a target region where treatment is to be administered. The sheath  103  contains and conveys the electrodes (not shown) to a desired treatment location. Positioning of the distal end  105  of the sheath  103  and the distal ends of the electrodes (not shown in  FIG. 1 ) may be controlled by the user interface  102  received by the electrosurgical apparatus  118  as further described below with reference to  FIGS. 6A-21B . 
     Referring to  FIGS. 2-5 , distal ends of components used to administer treatment are positioned relative to a target region  202  using various embodiments of a user interface  102 . The target region  202 , may include a lesion or any portion of tissue to be treated within a body. Various embodiments of the user interface  102  described below are capable of positioning the components as described with reference to  FIGS. 2-5  and as further described with reference to  FIGS. 6A-21B . The description of  FIGS. 2-5  is provided as a baseline to describe an application with which various embodiments of the user interface  102  may be used to deploy these components. 
     In various embodiments, a secondary electrode  211  is slidably received within a primary electrode  207 , and the primary electrode  207  is slidably received within a sheath  203 . Components contained within other components are represented with dashed lines in  FIGS. 2-5 . In various embodiments, the primary electrode  207  is in the form of a needle, with the distal end  209  being configured to pierce tissue, such as tissue comprising the target region  202 . Piercing the tissue at the target region  202  with the primary electrode facilitates positioning the distal end  209  of the primary electrode  207  at a desired position and also facilitates conveying the secondary electrode  211  to a desired location. In various embodiments, until a user interface is manipulated to separately move the secondary electrode  211 , the primary electrode  207  and the secondary electrode  211  move in concert, at a same time and through a same distance, with each other and with the sheath  203 . 
     Referring to  FIG. 2 , the sheath  103 , the primary electrode  207 , and the secondary electrode  211  are positioned at an initial position near the target region  202 . The sheath  103  and the electrodes  207  and  211  received therein may be conveyed to this location through the use of a bronchoscope or other electrosurgical device  118 , as previously described with reference to  FIG. 1 . A distal end  105  of the sheath  103  is positioned in the vicinity of the target region  202 . The primary electrode  207  is slidably received within the sheath  103 , with a distal end  209  of the primary electrode  207  at or near the distal end  105  of the sheath  103 . Specifically,  FIG. 2 , for example, shows the distal end  209  of the primary electrode  207  positioned just short of the distal end  105  of the sheath  103 . In turn, the secondary electrode  211  is slidably received within the primary electrode  207 , with the distal end  213  of the secondary electrode  211  positioned just within the distal end  209  of the primary electrode  207 . 
     Referring to  FIG. 3 , the sheath  103 , the primary electrode  207 , and the secondary electrode  211  are positioned once the sheath  103  has been moved closer to the target region  202 . The sheath  103  may be moved toward the target region  202  using a sheath actuator, as described below with reference to  FIGS. 6A-7B . 
     As contrasted with  FIG. 2 , in  FIG. 3 , the distal end  105  of the sheath  103  has been moved closer to the target region  202 . Because the primary electrode  207  and the secondary electrode  211  have not been separately moved through the manipulation of a user interface (not shown), the primary electrode  207  and the secondary electrode  211  have moved in concert with the sheath  103 , traveling a same distance in a same direction as the sheath  103 . The distal end  209  of the primary electrode  207  remains positioned just short of the distal end  105  of the sheath  103 , and the distal end  213  of the secondary electrode  211  remains positioned just within the distal end  209  of the primary electrode  207 . 
     Referring to  FIG. 4 , the sheath  103 , the primary electrode  207 , and the secondary electrode  211  are positioned once the primary electrode  207  has been extended from the sheath  103  into the target region  202 . In various embodiments, the secondary electrode  211  moves in concert with the primary electrode  207  as the primary electrode  207  is extended beyond the distal end  105  of the sheath  103 . Thus, the secondary electrode  211  moves in the same direction and moves through the same distance as the primary electrode  207 , as shown in  FIG. 4 . The distal end  213  of the secondary electrode  211  remains positioned just within the distal end  209  of the primary electrode  207 . 
     Referring to  FIG. 5 , the sheath  103 , the primary electrode  207 , and the secondary electrode  211  are positioned once the secondary electrode  211  has been extended from the primary electrode  207 . A distal end  213  of the secondary electrode  211  is deployed at a position across the target region  202  from the primary electrode  207 . In particular embodiments, the secondary electrode  211  is configured as a coilable wire which is constrained within the primary electrode  207  in a straightened form. The secondary electrode  211  may be formed of an alloy, such as nitinol, a nickel-titanium allow, or other “memory” alloy to regain a certain shape after being released from a confined position. Once the user interface  102  (not shown in  FIG. 5 ) is manipulated to independently extend the secondary electrode  211  from the primary electrode  207 , a portion of the secondary electrode  211  coils. As a result, the distal end  213  of the secondary electrode  211  augers into tissue at the target region  202 . The augering of the distal end  213  of the secondary electrode  211  may assist in securing the position of the distal end  213  of the secondary electrode  211  during treatment. 
     Still referring to  FIG. 5 , an insulated section  515  of the secondary electrode  211  stops short of the distal end  213  of the secondary electrode  211 . The insulation  515  electrically insulates the secondary electrode  211  from the primary electrode  207  such that, when electrical current is applied to proximal ends (not shown) of the primary electrode  207  and the secondary electrode  211 , the electrical current may only flow between the distal end  209  of the primary electrode  207  and the uninsulated distal end  213  of the secondary electrode  211 . 
     As will be further described below, various embodiments of the user interface  102  facilitate moving the primary electrode  207  and the secondary electrode  211  in concert with the sheath  103  as the sheath is positioned adjacent the target region  202 , as described with reference to  FIG. 3 . Various embodiments of the user interface also facilitate moving the primary electrode  207  and the secondary electrode  211  in concert as they are extended beyond the distal end  105  of the sheath  103 , as described with reference to  FIG. 4 . To this end, various embodiments of the user interface  102  may prevent moving the secondary electrode  211  independently of the primary electrode  207  until the primary electrode  207  is extended beyond the distal end  105  of the sheath  103 . Once the primary electrode  207  has been extended, various embodiments of the user interface facilitate moving the secondary electrode  211  independently of the primary electrode  207  to permit separate positioning of the secondary electrode, as described with reference to  FIG. 5 . Further, once the primary electrode  207  is deployed at a desirable position, various embodiments of the user interface may prevent the primary electrode  207  from being moved while the secondary electrode  211  is being separately deployed and/or once the secondary electrode  211  has been situated at a desired location. Embodiments of a user interface  102  to coordinate movements of the sheath  103  and electrodes  207  and  211  is explained below with reference to  FIGS. 6A-20 . 
     Referring to  FIGS. 6A and 6B , the user interface  102  includes a sheath actuator  604  that is used to position the distal end  105  of the sheath  103 , as previously described with reference to  FIG. 3 . The user interface  102  is joined with the electrosurgical apparatus  118  with the coupler  150 , as previously described with reference to  FIG. 1 . The electrosurgical apparatus  118 , such as a bronchoscope or another minimally invasive device used for performing diagnostic or therapeutic tasks, conveys the sheath  103  into the body (not shown in  FIGS. 6A and 6B ) near the target region  202 . 
     Again referring to  FIG. 6A , the user interface  102  includes a sheath actuator  604  and a sheath lock  606  configured to move the sheath  103  to position the distal end  105  of the sheath  103  at a desired location relative to a target region  202 . In some embodiments, the sheath actuator  604  may be a slidable mechanism incorporating a slidable sleeve  612 . At one end, the slidable sleeve  612  is slidably received within a collar  614  at an end of a housing  610  of the user interface  102 . At an opposing end, the slidable sleeve  612  is joined with the coupler  150 . The slidable sleeve  612  may be locked in position at the collar  614  by the sheath lock  606 . The sheath lock  606  may include a thumbscrew, a spring-loaded locking pin, or another mechanism configured to mechanically engage the slidable sleeve  612  to secure the slidable sleeve  612 —and, in turn, the sheath  103 —in place at a desired location. In some other embodiments, the sheath actuator  604  may, for example, be part of the electrosurgical apparatus  118 . Any such embodiments of the sheath actuator  604  may facilitate movement of the sheath  103 , as further described below. 
     Referring to  FIG. 6B , before engaging the sheath actuator  604  to extend the sheath  103 , the sheath  103  and the primary electrode  207  and the secondary electrode  211  received therein are positioned near the target region  202 , as shown in  FIG. 2 . 
     Referring to  FIGS. 7A and 7B , manipulation of the sheath actuator  604  illustrates an example of how the sheath  103  may be unlocked and moved into position as previously described with reference to  FIG. 3 . In the configuration shown in  FIGS. 7A and 7B , the sheath actuator  604  has been manipulated to enable the sheath  103  to be moved a distance  719  closer to the target region  202 . Specifically, the sheath lock  606  of the sheath actuator  604  is released to enable movement of the slidable sleeve  612  within the collar  614 . Then, the housing  610  of the user interface  102  is moved a distance  719  relative to the electrosurgical device  118  to move the sheath  103  the same distance  719  toward the target region  702 . Once the distal end  105  of the sheath  103  has reached the desired location relative to the target region  202 , the slidable sleeve  612  may be locked in position at the collar  614  by the sheath lock  606 . In various embodiments of the user interface  102 , the electrodes  207  and  211  move with the housing  610 , so that when the housing  610  is moved to reposition the sheath  103 , the electrodes  207  and  211  move in concert with the sheath  103 . Therefore, as shown in  FIG. 7B , while the distal end  105  of the sheath  103  is advanced toward the target region  202 , the electrodes  207  and  211  move with the sheath  203 . As in  FIG. 6B , the distal end  209  of the primary electrode  207  remains within the distal end  105  of the sheath  103  and the distal end  213  of the secondary electrode  211  remains within the distal end  209  of the primary electrode  207 . 
     Referring to  FIG. 8 , in an illustrative sheath actuator  604  and a sheath lock  606  the slidable sleeve  612  is slidably received within the collar  614  of the housing  610 . The slidable sleeve  612  is fixably attached to the coupler  150  that engages the user interface  102  with the electrosurgical apparatus (not shown in  FIG. 8 ). The sheath lock  606  in the embodiment of  FIG. 8  is a thumbscrew that may be loosened to permit movement of the collar  614  fixably attached to the coupler  150  to move the sheath (not shown in  FIG. 8 ) as previously described with reference to  FIGS. 6A-7B . After the housing  610  has been manipulated to slide the collar  614  relative to the slidable sleeve  612  to move the distal end  105  of the sheath  103  to a desired location, such as described with reference to  FIG. 7B , the sheath lock  606  is reengaged, such as by turning a thumbscrew, to fix the position of the sheath. 
     Referring to  FIG. 9 , the sheath  103  and the electrodes  207  and  211  extend through the slidable sleeve  612 . As a result, movement of the housing  610 , to which the sheath  103  and the electrodes  207  and  211  are operably coupled, results in movement of the sheath  103  and the electrodes  207  and  211 . A distal end  907  of the sheath lock  606  that extends through the collar  614  mechanically engages the slidable sleeve  612  to control movement of the slidable sleeve  612 . Releasing the sheath lock  606 , such as by loosening a thumb screw, permits the slidable sleeve  612  to be slidably moved relative to the collar  614  by moving the housing  610 , as described with reference to  FIG. 7A . Securing the sheath lock  606 , such as by tightening the thumbscrew, mechanically secures the slidable sleeve  612  in place relative to the collar  614 , preventing further movement of the slidable sleeve  612 , thereby securing the distal end  105  of the sheath  103  in place. 
     Referring to  FIG. 10 , in various embodiments, the user interface  102  includes control surfaces for positioning the sheath  103  and the electrodes  207  and  211  (none of which are shown in  FIG. 10 ). The user interface  102  includes the housing  610  that supports components that are moved parallel along an axis  1001  or that are rotated along a curve  1003  around the axis  1001 , as further described below. The user interface  102  includes the sheath actuator  604 , including the collar  614  that receives the slidable sleeve  612  (fully received within the collar  614  and, thus, not shown in  FIG. 10 ) and the sheath lock  606 . The sheath actuator  604  joins the housing  610  to the coupler  150  which, in turn, couples the user interface  102  with an electrosurgical device (not shown in  FIG. 10 ). As further described in more detail below, the user interface  102  includes a primary actuator  1010 , which controls movement of the primary electrode  207  (not shown in  FIG. 10 ), and a secondary actuator  1020 , which controls movement of the secondary electrode  211  (not shown in  FIG. 10 ). 
     The primary actuator  1010  includes a depressible actuator lock  1012  that extends through an actuator opening  1014  in the primary actuator  1010 . The primary actuator  1010  is slidably engaged with the housing  610 . The actuator lock  1012  is hingably or flexibly mounted on the primary actuator  1010 . Depressing the actuator lock  1012  partially moves the actuator lock  1012  through the actuator opening  1014  and a corresponding opening or recess (not shown in  FIG. 10 ) in the housing  610  to disengage the primary actuator  1010  from the housing  610 . As a result, depressing the actuator lock  1012  permits the primary actuator  1010  to slide along the axis  1001 , as further described below. The secondary actuator  1020  includes an actuator knob  1022  that is engageable to rotate the secondary actuator  1020  through the curve  1003  around the axis  1001 , as also further described below. As also further described below, in various embodiments, actuator interlocks restrict movement of the secondary actuator  1020  until the primary actuator  1010  is moved to extend the primary electrode  207  (not shown in  FIG. 10 ), and restrict movement of the primary actuator  1010  once the secondary actuator  1020  is moved to extend the secondary electrode  211 . 
     Referring to  FIG. 11 , various components of the user interface  102 , including portions of the housing  610 , the primary actuator  1010 , and the secondary actuator  1020  illustrate the interrelationship of the components in various embodiments. The housing  610  ( FIG. 10 ) includes a first housing section  1131  and a second housing section  1133 . The housing sections  1131  and  1133  have hollow interiors to receive and permit movements of other components arranged therein. A first housing section  1131  internally supports a locking rack  1128  that engages the actuator lock  1012 . More specifically, the locking rack  1128  includes recesses having openings facing inwardly into the housing  610  to permit selective engagement with the actuator lock  1012 . The second housing section  1133  also may include a depth scale  1134  that may be used to visually gauge a position of the primary electrode  207  based on a position of the primary actuator  1010  relative to the housing  610 . A second housing section  1133  threadably supports the sheath lock  606 , which is part of the sheath actuator  604 , as previously described with reference to  FIGS. 6A-9 . The housing sections  1131  and  1133  are matable sections, joinable by adhesives or fasteners, such as screws (not shown in  FIG. 11 ). 
     In various embodiments, primary actuator sections  1111  and  1113  are slidably received around the housing section  1131  and  1133 . The primary actuator sections  1111  and  1113  are have generally hollow interiors to slidably receive the housing sections  1131  and  1133  therebetween. A first primary actuator section  1111  defines the actuator opening  1014  that receives the actuator lock  1012 . The actuator lock  1012  has a base  1124  that is fixably securable to the first primary actuator section  1111  and around which the actuator lock  1012  partially rotates into an opening or recess (not shown in  FIG. 11 ) in the housing  610  when the actuator lock  1012  is depressed. At an end opposite the base  1124 , the actuator lock  1012  also supports a pin support  1126  that holds a pin  1127  that engages the locking rack  1128  of the first housing section  1131  when the actuator lock  1012  is not depressed. 
     In various embodiments, the actuator lock  1012  is biased into a locking position where the pin support  1126  causes the pin  1127  to engage the locking rack  1128  when the actuator lock  1012  is released. The actuator lock  1012  may be biased by rigidity of the actuator lock  1012  causing the actuator lock  1012  to resume its undeformed position when the actuator lock  1012  is released. Alternatively, the actuator lock  1012  may be spring loaded by a spring actuator (not shown) positioned between the actuator lock  1012  and the housing  610 . The primary actuator sections  1111  and  1113  are joinable by adhesives or fasteners, such as screws (not shown in  FIG. 11 ). 
     Another portion of the primary actuator  1010  is a secondary actuator guide, comprised of guide sections  1151  and  1153  couplable to the primary actuator sections  1111  and  1113 . As described in more detail with reference to  FIGS. 22 and 23 , the guide sections  1151  and  1153  are joinable at their ends to form an annular tube and, between their respective edges, define a helical channel that receive guide members  1136  and  1138  extending outwardly from secondary actuator sections  1121  and  1123 . The engagement of the guide members  1136  and  1138  with the helical channel defined by edges of the guide sections  1151  and  1153 , with reference to  FIG. 10 , cause the secondary actuator  1020  to advance along the axis  1001  when the secondary actuator  1020  is rotated through a curve  1003  around the axis  1001 . 
     In various embodiments, secondary actuator sections  1121  and  1123  are rotatably mounted between the housing sections  1131  and  1133 . The secondary actuator sections  1121  and  1123  are generally hollow to receive therebetween other components of the user interface  102 . As previously described, each of the secondary actuator sections  1121  and  1123  outwardly support the guide members  1136  and  1138  that engage the helical channel defined by edges of the guide sections  1151  and  1153 . Ends  1129  and  1139  of the respective secondary actuator sections  1121  and  1123  are shaped to engage the actuator knob  1022  used to rotate the secondary actuator  1020 , as will be further described below with reference to  FIGS. 16A and 17A . The secondary actuator sections  1121  and  1123  are joinable by adhesives or fasteners, such as screws (not shown in  FIG. 11 ). 
     In various embodiments, the primary actuator  1010  and the secondary actuator  1020  include actuator interlocks to control relative movement of the actuators  1010  and  1020 . In various embodiments, a first secondary actuator half  1121  may support a recess  1137  and a locking member  1139  to control relative movements of the primary actuator  1010  and the secondary actuator  1020 . The recess  1137  may be configured to receive the pin support  1126  extending from the actuator lock  1012  to enable the actuator lock  1012  to be depressed to advance the primary actuator  1010 . However, after the primary actuator  1010  is moved, the actuator lock  1012  is released, and the secondary actuator  1020  is rotated, the rotation of the secondary actuator  1020  results in the recess  1137  being displaced from under the pin support  1126 . As a result of the displacement, the actuator lock  1012  is no longer depressible because a body of the secondary actuator  1020  blocks the pin support  1126 , thereby preventing depressing of the actuator lock  1012 . However, after the secondary actuator  1020  is returned to its starting position, the recess  1137  again rotates beneath the pin support  1126 , allowing depressing of the actuator lock  1012  to permit movement of the primary actuator  1010 . 
     Similarly, to prevent rotation of the secondary actuator  1020  before the primary actuator  1010  is moved to deploy the primary electrode  207 , the locking member  1139  may engage a notch (not shown) in the housing  610 . After the actuator lock  1012  is depressed and the primary actuator  1010  is moved relative to the housing  610  to deploy the primary electrode  207 , the locking member  1139  clears the housing  610 . It should be noted that the recess  1137  will continue to receive the pin support  1126  as long as the actuator lock  1012  is depressed, continuing to prevent rotation of the secondary actuator  1020 . Once the actuator lock  1012  is disengaged, the secondary actuator  1020  is rotatable to deploy the secondary electrode  211  and to block the actuator lock  1012  from being engaged to permit movement of the primary actuator  1010 . Thus, in sum, the actuator interlocks ensure that the primary actuator  1010  be moved to deploy the primary electrode  207  before the secondary actuator  1020  may be rotated. Then, once the primary actuator  1010  has been moved to deploy the primary electrode  207  and the secondary actuator  1020  is rotated from its starting position, the actuator interlocks prevent the primary actuator  1010  and the primary electrode  207  from being moved until the secondary actuator  1020  is moved to retract the secondary electrode  211  to its original position. 
     The user interface  102  also includes a sheath mount  1135  that is receivable between the housing sections  1131  and  1133  to mechanically engage the housing  610  with the sheath  103 . As a result, as described with reference to  FIGS. 6A-9 , movement of the housing  610  extends or retracts the sheath  103 . The user interface also includes electrode sliders coupled with the respective electrodes  207  and  211 . A primary electrode slider  1145  is mechanically engageable by the primary actuator sections  1113  and  1133  so that sliding the primary actuator  1010  advances or retracts the primary electrode slider  1145  to advance or retract the primary electrode  207 , respectively. A secondary electrode slider (not shown in  FIG. 11 ) mechanically engageable by the secondary actuator sections  1121  and  1123  is slidably received within the primary electrode slider  1145 . Because the secondary actuator sections  1121  and  1123  are rotatably moved, as further described below, the secondary electrode slider is also rotatably received between the secondary actuator sections  1121  and  1123 . 
     A flexible wiring harness  1150  is configured to receive one or more conductors of the electrical conductor  130  ( FIG. 1 ) at a port on the housing  610  (not shown in  FIG. 11 ), and to electrically connect with flexible leads  1152  and  1154 , each of which connects with one of the electrodes  207  and  211 . The flexible leads  1152  and  1154  are configured to remain electrically connected with the electrodes  207  and  211  as proximal ends of the electrodes  207  and  211  are moved within the user interface  102 . 
     Additionally, a flexible fluid coupling  1160  extends from a fluid port (not shown in  FIG. 11 ) on the housing  610  to an interior of the primary electrode slider  1145  to convey fluid into a lumen defined within the primary electrode  207 . The fluid port receives the tube  132  from the infusion pump  116  ( FIG. 1 ) at the housing  610  to receive a flow of conductive fluid. The flexible fluid coupling  1160  may be coiled within the housing  610  to permit extension and contraction of the fluid coupling  1160  with the movement of the primary electrode slider  1145  relative to the housing  610 . 
     As further described below with reference to  FIGS. 27 and 28 , the coupler  150  includes a slidable locking body  1180  that is slidably received between a slidable mount  1182  and a retaining ring  1184 . The slidable mount  1182  is coupled with the housing  610 . As further described below, once the housing  610  is positioned to engage the electrosurgical device  118  (not shown in  FIG. 11 ), the locking body  1180  is slid into place to secure the connection, as further described with reference to  FIGS. 27 and 28 . 
     Referring to  FIGS. 12A-21B , operation of the user interface  102  and corresponding movements of the sheath  103 , the primary electrode  207 , and the secondary electrode  211  are described. 
     Referring to  FIGS. 12A and 12B , the distal end  105  of the sheath  103  is positioned adjacent to the target region  202 . As previously described with reference to  FIGS. 6A-7B , in various embodiments, the sheath actuator  604  enables the sheath  103  to be positioned by releasing the sheath lock  606  and moving the housing  610 . For example, referring again to  FIGS. 6A-7B , a position of the sheath  103  is controlled by sliding the slidable sleeve  612  within the collar  614 , then securing the sheath  103  at the desired location by reengaging the sheath lock  606 . When the distal end  105  of the sheath  103  is deployed adjacent to the target region  202 , a distal end  209  of the primary electrode  207  lies just within the distal end  105  of the sheath  103 . At the same time, the distal end  213  of the secondary electrode  211  lies just within the distal end  209  of the primary electrode  207 . With the distal end  105  of the sheath  103  positioned adjacent the target region  202 , the user interface  102  may be used to move the electrodes  207  and  211  to desired positions. 
     Referring to  FIGS. 13A and 13B , according to various embodiments, positioning the electrodes  207  and  211  begins with depressing the actuator lock  1012  to enable movement of the primary actuator  1010 . Depressing the actuator lock  1012  to move the actuator release  1012  in a direction  1301  disengages the primary actuator  1010  from the housing  610 . Specifically, depressing the actuator lock  1012 , which is hingably or rotatably coupled with the primary actuator  1010  at the base  1124 , causes the pin support  1126  to move the pin  1127  from inward-facing recesses of the locking rack  1128  on the housing  610 . With the pin  1127  removed from the locking rack  1128 , the primary actuator  1010  is movable relative to the housing  610  to move the primary electrode  207 , as described with reference to  FIGS. 14A and 14B . 
     As previously described, the secondary actuator  1020  is rotatably engaged with the primary actuator  1020 . Accordingly, the secondary actuator  1020  remains engaged with the primary actuator  1010  even when the actuator lock  1012  is released to release the primary actuator  1010  from the housing  610 . Therefore, depressing the actuator lock  1012  frees the primary actuator  1010  and the secondary actuator  1020  to move collectively, thus enabling the primary electrode  207  and the secondary electrode  211  to be moved collectively. 
     Referring to  FIGS. 14A and 14B , while a user continues to depress the actuator lock  1012  in the direction  1301 , the primary actuator  1010  is moved in a direction  1401 . Because the secondary actuator  1020  remains (rotatably) engaged with the primary actuator  1010  as previously described, the primary actuator  1010  and the secondary actuator move collectively the same distance in the direction  1401 , as represented in  FIG. 14A . 
     As a result of the collective movement of the primary actuator  1010  and the secondary actuator  1020 , the primary electrode  207  and the secondary electrode  211  move collectively as well. Thus, as depicted in  FIG. 14B , the distal end  209  of the primary electrode  207  and the distal end  213  of the secondary electrode  211  move collectively beyond the distal end  105  of the sheath  103  into the target region  202 . Thus, by virtue of the engagement of the secondary actuator  1020  with the primary actuator  1010 , depressing the actuator lock  1012  and moving the primary actuator  1010  moves both electrodes  207  and  211  collectively. 
     As previously described with reference to  FIG. 11 , with the actuator lock  1012  depressed, in various embodiments, the pin support  1026  on the actuator release  1012  engages the secondary actuator  1020 , preventing the secondary actuator  1020  from being rotated until the actuator release  1012  is disengaged. As also previously described, the secondary actuator  1020  may include the locking member  1139  that abuts the housing  610 . This arrangement prevents the secondary actuator  1020  from being rotated before the actuator lock  1012  is depressed and the primary actuator  1010  and the secondary actuator  1020  are advanced. 
     Referring to  FIGS. 15A and 15B , once the distal ends  209  and  213  of the primary electrode  207  and the secondary electrode  211 , respectively, have been advanced into the target region  202 , the actuator lock  1012  is released. Because the actuator lock  1012  is biased by its rigidity or by a spring, as described with reference to  FIG. 11 , releasing the actuator lock  1012  results in the actuator lock  1012  moving in a direction  1501 . The movement of the actuator lock  1012  causes the primary actuator  1010 —and the rotatably engaged secondary actuator  1020 —to again be engaged with the housing  610 , holding the electrodes  207  and  211  in place. As described with reference to  FIG. 11 , when the actuator lock  1012  is released, a pin  1127  mounted in the pin support  1026  moves into recesses in the locking rack  1128  mounted on the housing  610 . Thus, the engagement of the pin  1127  with the locking rack  1128  prevents further movement of the primary actuator  1010  until the actuator lock  1012  is further engaged by a user. Accordingly, with the user releasing the actuator lock  1012 , the distal ends  209  and  213  of the primary electrode  207  and the secondary electrode  211  are secured in the locations to which they were moved as described with reference to  FIGS. 14A and 14B . 
     Referring to  FIGS. 16A and 16B , with the primary actuator  1010  held in place by the user&#39;s release of the actuator lock  1012 , the secondary actuator  1020  is rotated to move the secondary electrode  211  independently of the primary electrode  207 . As shown in  FIG. 16A , the secondary actuator  1020  is moved by a user rotating the actuator knob  1022  in a direction  1601 . As previously described with reference to  FIG. 11 , the secondary actuator  1020  supports guide members  1136  and  1138  that are received within the helical channel defined between edges of the guide sections  1151  and  1153 . With the secondary actuator  1020  engaged with the helical channel defined by the guide sections  1151  and  1153 , rotation of the actuator knob  1022  results in helical movement of the secondary actuator  1020 . The rotation of the secondary actuator  1020  thus causes the secondary actuator  1020  to advance in a direction  1602  relative to the primary actuator  1010  and the housing  610 . 
     Referring to  FIG. 16B , movement of the secondary actuator  1020  results in the distal end  213  of the secondary electrode  211  extending beyond the distal end  207  of the primary electrode  209 . As previously described with reference to  FIG. 5 , the distal end  213  of the secondary electrode  211  may be preformed into a coiled shape, thereby resulting in the secondary electrode  211  forming a coiled shape once the secondary electrode  211  is no longer constrained within the lumen of the primary electrode  207 . In various embodiments, the coiled shape at the distal end  213  of the secondary electrode  211  augers into the tissue of the target region  202 , which secures the secondary electrode  211 —and the primary electrode  207  through which it extends—in position at the target region  202 . The insulated section  515  of the secondary electrode  211  electrically insulates the secondary electrode  211  from the primary electrode  207  except as between their respective distal ends  213  and  209 . With the distal ends  213  and  209  of the electrodes  211  and  207  deployed, a supply of conductive fluid and/or electrical current may be applied to the target region  202  as previously described to effect treatment. 
     The actuator interlocks presented by the configuration of the actuators  1010  and  1020  prevent the user from moving the primary actuator  1010  once the secondary actuator  1020  is rotated from its original position. As previously described with reference to  FIG. 11 , rotating the secondary actuator  1020  blocks the pin support  1126  of the actuator lock  1012 , thereby preventing a user from depressing the actuator lock  1012  to release the primary actuator  1010  from its engagement with the housing  610  via the pin  1127  and the locking rack  1128 . Thus, the distal end  209  of the primary electrode  207  remains in place as inserted into the target region  202  while the secondary actuator  1020  is moved to extend the distal end  213  of the secondary electrode  211  into the target region  202 . 
     Deployment of the sheath  103  and the electrodes  207  and  211  to permit the application of treatment is described with reference to  FIGS. 6A-7B and 12A-16B . Conversely, to withdraw and move the electrodes  207  and  211  from the target region  202 , manipulations and the sequence of manipulations of the user interface  102  is reversed, as described with reference to  FIGS. 17A-21B . 
     Referring to  FIGS. 17A and 17B , the distal end  213  of the secondary electrode  211  is retracted into the primary electrode  207  by a user rotating the actuator knob  1022  in a direction  1701 . The direction  1701  in which the actuator knob  1022  is rotated to retract the distal end  213  of the secondary electrode  211  from the target region  202  is opposite to the direction  1601  in which the actuator knob  1022  was rotated to extend the distal end  213  of the secondary electrode  211 . Rotation of the actuator knob  1022  results in an opposite, helical movement of the secondary actuator  1020 , resulting the secondary actuator  1020  translating in a direction  1702  relative to the primary actuator  1010  and the housing  610 . The movement of the secondary actuator  1020  withdraws the secondary electrode  211  until the distal end  213  of the secondary electrode  211  again is received within the distal end  209  of the primary electrode  207 . With the secondary actuator  1020  moved to its original position relative to the primary actuator  1010 , the actuator lock  1012  now may be released, as described with reference to  FIG. 18A . It will be appreciated that retraction of the secondary electrode  211  is accomplished by rotating the secondary actuator  1020  while the primary actuator  1010  remains stationary. 
     Referring to  FIGS. 18A and 18B , to prepare for retraction of the primary electrode  207  from the target region  202 , the actuator lock  1012  is depressed by a user in a direction  1801 . Depressing the actuator lock  1012  does not result in any movement of the distal ends  209  and  213  of the electrodes  207  and  211 , respectively, just as engagement of the actuator lock  1012  did not result in movement of the electrodes  207  and  211  when the actuator lock  1012  was depressed and released as previously described with reference to  FIGS. 13A and 13B  and  FIGS. 15A and 15B , respectively. 
     Referring to  FIGS. 19A and 19B , with the actuator lock  1012  depressed, the primary actuator  1010  is moved in a direction  1901  to withdraw the distal end  209  of the primary electrode  207  from the target region  202 . As previously described with reference to  FIGS. 14A and 14B , because the secondary actuator  1020  remains rotationally engaged with the primary actuator  1010 , the secondary actuator  1020  also moves a same distance and in the same direction  1901  as the primary actuator  1010 . As a result, the distal ends  209  and  213  of the electrodes  207  and  211  are moved collectively and withdrawn from the target region  202 . After the primary actuator  1010  is fully retracted in the direction  1901 , the distal end  209  of the primary electrode  207  is received within the distal end  105  of the sheath. Further, because the secondary actuator  1020 —and, thus, the secondary electrode  211 —moves in concert with the primary actuator  1010 , the distal end  213  of the secondary electrode  211  remains within the distal end  209  of the primary electrode  207  as the distal end  209  of the primary electrode  207  is withdrawn within the distal end  105  of the sheath  103 . 
     Referring to  FIGS. 20A and 20B , once the distal ends  209  and  213  of the electrodes  207  and  211 , respectively, are withdrawn within the distal end  105  of the sheath  103 , the actuator lock  1012  is released. Upon release of the actuator lock  1012 , the actuator lock  1012  moves in a direction  2001 . As a result, the pin  1127  held by the pin support  1126  reengages the locking rack  1128  to hold the primary actuator  1010  in place. Further, as previously described, the actuator interlocks that prevent the secondary actuator  1020  from being rotated, such as by the locking member  1139  extending from the secondary actuator  1020  engaging the housing  610 , prevents rotation of the secondary actuator  1020  while the actuators  1010  and  1020  have resumed a starting position as described with reference to  FIGS. 12A and 12B . 
     Referring to  FIGS. 21A and 21B , with distal ends  209  and  211  of the electrodes  207  and  211 , respectively, withdrawn within the distal end  105  of the sheath  103 , the sheath  103  itself may be withdrawn. In an operation opposite that depicted in  FIGS. 7A and 7B , the sheath lock  606  is released and the housing  610  is moved along the slidable sleeve  612  in a direction  2101  away from the coupling  150 . Because the primary actuator  1010  is locked to the housing by the actuator lock  1012 , and the secondary actuator  1020  is rotatably secured to the primary actuator  1010 , the primary actuator  1010  and the secondary actuator  1020  move in concert with the housing  610  in the direction  2101 . The sheath  103  and the insertion tube  119  ( FIG. 1 ) of the electrosurgical device  118  may then be withdrawn from the body. Alternatively, without withdrawing the sheath as described with reference to  FIGS. 21A and 21B , once the electrodes  207  and  211  are withdrawn into the sheath as described with reference to  FIGS. 19A-20B , the sheath  103  may be withdrawn from the body without first withdrawing the sheath  103  by engaging the sheath lock  606 . 
     As previously described with reference to  FIGS. 11, 16A, and 17A , the secondary actuator  1020  supports guide members  1136  and  1138  that engage a helical channel defined by edges of guide sections  1151  and  1153 . Referring to  FIG. 22 , the guide sections  1151  and  1153  are mated together into a guide sleeve  2202  as they are when joined with the primary actuator  1010 . The guide sections  1151  and  1153  may be joined at ends  2215  and  2217 . Specifically, as shown in  FIG. 23 , sockets  2330  may be supported by the guide sections  1151  and  1153  enabling the guide sections to be connected by screws, dowels, or other fasteners. 
     Between the ends  2215  and  2217  of the guide sleeve  2202 , edges  2211  and  2213  of the guide sections  1151  and  1153  define a helical channel  2201 . The helical channel  2201  guides the movement of the support members  1136  and  1138  to cause the secondary actuator  1020  to translate in response to rotation of the secondary actuator as described with reference to  FIGS. 16A and 17A . 
     In various embodiments, the generally helical channel  2201  has a varied pitch between the ends  2215  and  2217  of the guide sleeve  2202 . In various embodiments, the pitch may vary from a rearward end  2215 , where the secondary actuator  1020  begins its helical movement to extend the secondary electrode  207 , toward a forward end  2217 . More specifically, in various embodiments, the pitch of the helical channel is varied to reduce a distance of travel of the secondary actuator  1020  along the axis  1001  of the user interface  102  (not shown in  FIG. 22 ) per unit of rotation of the secondary actuator  1020  from the rearward end  2215  toward the forward end  2217 . 
     In various embodiments, the pitch is varied in this manner to reduce the rotational force to be applied by a user in turning the actuator knob  1022  to motivate the secondary actuator  1020 . For example, considering  FIGS. 5 and 16B , as the distal end  213  of the secondary electrode  211  is advanced into the target region  202 , the distal end  213  of the secondary electrode  211  may encounter increased resistance. Part of this resistance results from the distal end  213  of the secondary electrode  211  frictionally engaging a mass in the target region along an increasing length of the secondary electrode  211  as a longer section of the secondary electrode  211  is extended further beyond the distal end  209  of the primary electrode  207 . Part of this resistance may also result from the curvature of the of the coil at the distal end  213  of the secondary electrode  211  encountering an increasing degree of resistance in augering into the mass at the target region  202 . Correspondingly, greater force may be involved at the start of withdrawal of the secondary electrode  211  in frictionally engaging a greater mass of tissue than when the secondary electrode  211  is closer to being fully retracted into the distal end  209  of the primary electrode  207 . Further, when a portion of the secondary electrode  211  near the distal end  213  is formed into a coiled shape using a memory alloy, withdrawing the secondary electrode  207  may involve application of additional force in seeking to draw the secondary electrode into a deformed, straightened shape that the secondary electrode  211  assumes when confined within the primary electrode  207 . 
     As a result, in deploying the secondary electrode  211 , more force may be involved in extending the secondary electrode  211  as the secondary electrode  211  extends further beyond the distal end  209  of the primary electrode  207  into the target region  202 . As a result, a greater degree of rotational force may be involved in rotating the actuator knob  1022  of the secondary actuator  1020  as the secondary actuator  1020  moves toward the forward end  2217  of the guide sleeve  2202 . Correspondingly, more force may be involved the initial portion of withdrawing the secondary electrode  211  than when the secondary electrode  211  has been or nearly has been fully retracted into the primary electrode  207 . Therefore, a greater degree of rotational force may be involved in rotating the actuator knob  1022  of the secondary actuator  1020  as the secondary actuator  1020  first moves away from the forward end  2217  of the guide sleeve  2202 . 
     According to various embodiments, the pitch of the helical channel  2201  may be varied between the trailing end  2215  and the forward end  2217  of the guide sleeve  2202 . Specifically, the pitch of the helical channel  2201  may be varied to reduce a distance of travel of the second actuator  1020  along the axis  1001  per unit of rotation through the curve  1003  around the axis  1001  toward the forward end  2217  of the guide sleeve  2202  facing a forward end of the user interface  2202 . By reducing the distance of travel of the second actuator  1020  toward the forward end of the guide sleeve  2202 , the increased force along the axis  1001  is effectively spread over a greater degree of rotation of the second actuator  1020 . Thus, while lateral resistance to moving the secondary electrode  211  along the axis  1001  may increase at a forward end  2217  of the guide sleeve  2202 , the force involved in rotating the actuator knob  1022  to rotate the secondary actuator  1020  does not increase as much. 
     Referring to  FIG. 23 , because the pitch of the helical channel  2201  is defined by the edges  2211  and  2213  of the guide sections  1151  and  1153 , respectively, a pitch of the edges  2211  and  2213  is varied to define a helical channel  2201  of a desired shape. For example, considering the first guide section  1153 , at a first point  2301  toward a rearward end  2345  of the first guide section  1153 , a pitch angle a of the edge  2213  (as measured tangentially to the edge  2213  relative to the axis  1001 ) is greater than a pitch angle β at a second point  2302  moving toward the forward end  2347  of the first guide section  1153 . Similarly, the pitch angle β at the second point  2302  is greater than a pitch angle γ at a third point  2303  moving further toward the forward end  2347  of the guide section  1153 . A corresponding arrangement is repeated with the second guide section  1151 , with a pitch angle along the edge  2211  becoming less moving from a rearward end  2341  of the second guide section  1151  toward the forward end  2343 . As a result, despite increased resistance along the axis  1001 , rotational resistance applied to the secondary actuator  1020  is reduced by the decreasing pitch of the helical channel  2201  ( FIG. 22 ) defined by the decreasing pitch of the edges  2211  and  2213  of the respective guide sections  1151  and  1153 . 
     In addition to varying the pitch of the helical channel  2201  to facilitate deployment and withdrawal of the secondary electrode  207 , a cross-section of the wire used as the secondary electrode  207  also may ease the deployment and withdrawal of the secondary electrode  207 . Referring to  FIGS. 24-26 , the secondary electrode  207  may include a wire having portions  2410  and  2420  of different thicknesses along its length. 
     Referring to  FIG. 24 , a first portion  2410  of the secondary electrode  207  may have a circular cross-section with a first thickness  2412 . A second portion  2420  leading to the distal end  213  of the secondary electrode  211  may have a flat or rectangular cross-section having a second thickness  2422  that is less than the first thickness  2412 . In an illustrative embodiment, the first thickness  2412  of the circular cross-section of the first portion  2410  may be 0.015 inches, and the second thickness  2422  of the second portion may be 0.009 inches. In such a configuration, a theoretical moment of inertia for the first portion  2410  is more than twice that of a theoretical moment of inertia for the second portion  2420 . The greater theoretical moment of inertia of the first portion  2410  thus should improve the force transmission of the first portion  2410  in advancing the secondary electrode  207  without impeding the capacity of the second portion  2420  to assume its coiled configuration upon deployment. The first thickness  24212  is aligned with an axis  2430  that defines a plane in which the second portion  2402  will coil, as depicted in  FIG. 25 . 
     Referring to  FIG. 26 , the secondary electrode  211  is in an uncoiled configuration. The second portion  2420  may have a second width  2624  that is wider than the second thickness  2422  of the second portion  2420  and wider than the first thickness  2412  of the first portion  2410 . In a non-limiting example, the first thickness  2412  may be 0.015 inches, the second thickness may be 0.009 inches, and the second width may be 0.020 inches. 
     A secondary electrode  211  with the first portion  2410  having a circular cross-section provides good column strength and force transmission for motivating the secondary electrode  211  along its length. The column strength and force transmission are helpful in driving the secondary electrode  211  through the lumen within the primary electrode  207  and in extending the secondary electrode  211  into a tissue at a target region, as depicted in  FIG. 5 . By contrast, with the second portion  2420  having a reduced thickness in the plane in which the second portion  2420  of the secondary electrode  211  is to coil makes it easier for the secondary portion to assume its coiled shape. Using the exemplary dimensions, the moment of inertia of the second portion  2420  is less than half of that of the first portion  2410 , reducing the force required to coil and uncoil the second portion  2410 . Having a second width  2624  that is larger than the second thickness  2422  and larger than the first thickness  2412  improves the column strength and force transmission of the second portion  2420  to keep the second portion  2420  from buckling, while still having a thinner second thickness  2422  that facilitates the coiling of the second portion  2420 . 
     Referring to  FIG. 27 , the coupler used to secure the user interface  102  with the electrosurgical device  118  includes a slidable mounting mechanism  2710  and a locking body  2720 . In various embodiments, the slidable mounting mechanism  2710  is secured to the slidable sleeve  612  extending from the housing of the user interface (not shown in  FIG. 27 ) and fits around the slidable sleeve  612 . The slidable sleeve  612  has an internal width  2791  that is sized to receive a flange  2754  at an end of a device interface  2752 . The flange  2754  has an outer width  2793  that is less than the internal width  2791  of the slidable sleeve  612  so that the flange  2754  is receivable within an end of the slidable sleeve  612 . The device interface  2752  has an outer width  2795  that is less than the outer width  2793  of the flange  2754  that it abuts. The outer width  2795  of the device interface  2795  and the outer width  2793  of the flange  2754  are considered in the configuration of the locking body  2720 , as further described below with reference to  FIG. 28 . 
     The slidable mounting mechanism  2710  includes a base portion  2712  that is fixed, fixable, or connected to the slidable sleeve  612  (the slidable mounting mechanism  2710  is shown in  FIG. 27  prior to being fixably connected to the slidable sleeve  612 ). The slidable mounting mechanism  2710  also includes one or more projections  2714  that are configured to receive retaining clips  2734  extending from a retaining ring  2730  to secure the lock plate  2720  to the slidable mounting mechanism  2710 , as further described below. 
     The slidable mounting mechanism  2710  also supports a locking pin  2716 . In various embodiments, the locking pin  2716  is spring-loaded or otherwise biased to extend outwardly from the slidable mounting mechanism  2710  to engage a locking slot in the locking body  2720  to prevent the locking body  2720  from sliding. The locking pin  2716  may be manually retracted away from the locking body  2720  to permit the locking body  2720  to be moved to an unlocked position. 
     In various embodiments, the slidable mounting mechanism  2710  includes a torque transfer mechanism to transfer torque between the electrosurgical instrument or device  118  ( FIG. 1 ) and the user interface  102 . In various embodiments, the torque transfer mechanism includes a linkage  2728  that is received within a channel  2718  when the locking body  2720  is in a locked position. The linkage  2728  and the channel  2718  thus transfer torque between the locking body  2720  that is engaged with the electrosurgical instrument or device  118  and the slidable sleeve  612 . The linkage  2718  and channel  2728  thus absorb and/or transfer torque between the electrosurgical instrument or device  118  and the slidable sleeve  612 , rather than, for example, the torque being exerted on the retaining ring  2730  and/or the locking pin  2716 . In various embodiments, torque also may be absorbed and transferred by strengthening the locking pin  2716  and/or tightening and strengthening the mounting of the retaining ring  2730  to the lock plate  2720 . 
     The locking body  2720  has a base plate  2722  configured to slide across the slidable mounting mechanism  2710  and to hold the flange  2754  in place within the slidable sleeve  612  to secure the user interface  102  to the electrosurgical device  118 . As further described with reference to  FIG. 28 , the base plate  2722  defines an opening having differently-sized sections that alternately permit insertion of the flange  2754  into the slidable sleeve  612  and prevent removal of the flange  2754  from the slidable sleeve  612 . The locking body  2720  supports a hood  2724  that extends over the combination formed by the surgical device interface  2752  with the user interface  102  via the slidable sleeve  612 . As previously mentioned, the locking body  2720  also supports the second indicator tab  2728 . The second indicator tab  2728  aligns with the first indicator tab  2718  on the slidable mounting mechanism  2710  when the locking body  2720  is in a locked position to provide visual confirmation when the locking body  2720  is in a locked position. 
     The locking body  2720  is slidably secured to the slidable mounting mechanism with a retainer ring  2730 . The retainer ring  2730  includes a ring  2732  having an inner diameter  2799  that is sized to receive the flange  2754  extending from the surgical device interface  2752  therethrough. Extending from the ring  2732  are one or more retaining clips  2734 . The retaining clips  2734  are sized to fit through slots in the base plate  2722  of the locking body, as further described below with reference to  FIG. 28 . Once the retaining clips  2734  are extended through the slots in the base plate  2722  of the locking body  2720 , the retaining clips are secured onto and/or around the projections  2714  on the slidable mounting mechanism  2710 . Once the retaining clips  2734  are extended through the slots on the locking body  2720  and secured onto the projections  2714  on the slidable locking mechanism  2710 , the locking body  2720  is slidably constrained to move across the slidable mounting mechanism  2710  to lock and unlock the user interface  102  with the electrosurgical device  118 . 
     Referring to  FIG. 28 , the base plate  2722  defines two retaining slots  2895  through which the retaining clips  2734  ( FIG. 27 ) extend from the retaining ring  2730 . The retaining slots  2895  are sized to slidably receive the retaining clips  2734  so that the locking body  2720  can slide in a first direction  2815  or a second direction  2817  across the retaining clips  2734 . The ring  2732  of the retaining ring  2730  lies across the base plate  2722  to hold the locking body  2720  to the slidable mounting mechanism  2710  ( FIG. 27 ). The locking body  2720  also supports at least one socket  2820  to receive the locking pin  2716  ( FIG. 27 ) extending from the slidable locking mechanism  2710 . The socket  2820  is positioned to engage the locking pin  2716  when the locking body  2720  is slid into a locked position over the surgical device interface  2752 . 
     The hood  2724  extends from the locking plate  2722  to cover the connection between the surgical device interface  2752  and the user interface  102 . To allow the locking body  2720  to move in the second direction  2817  without the hood  2724  being blocked by a body of the electrosurgical device  118  ( FIG. 1 ), a lower edge  2825  of the hood  2724  is shaped to define a recess  2827 . When the locking body  2720  is moved in the second direction  2817  to move the locking body  2720  into a locked position, the recess  2827  receives the body of the electrosurgical device  118 . 
     The base plate  2722  of the locking body  2720  defines an opening  2810  through which, as described with reference to  FIG. 27 , the flange  2754  on the surgical device interface  2772  may be inserted into the slidable sleeve  612 . More specifically, a first section  2801  of the opening has a first width  2811  and a conjoined second section  2803  with a second width  2813 . The first width  2811  of the first section is large enough to receive the outer width  2793  of the flange  2754  therethrough, while the second width  2813  of the second section  2803  is large enough to receive the width  2795  of the surgical device interface  2752  but not to allow the outer width  2793  of the flange  2754  to pass therethrough. 
     To lock the user interface  102  with the electrosurgical device  118  (not shown in  FIG. 28 ), the locking body  2720  is slid in the first direction  2815  to position the first section  2801  over the opening in the base portion  2712  of the slidable mounting mechanism  2710  that leads into the slidable sleeve  612  (not shown in  FIG. 28 ). The flange  2754  that extends from the surgical device interface  2752  is then inserted through the first section  2801  and into the slidable sleeve  612 . To secure the surgical device interface  2752  in place, the locking body is slid in the second direction  2817 . As a result, the second section  2803  is moved over the opening in the base portion  2712  of the slidable mounting mechanism  2710 , and an edge of the locking body  2722  slides over and abuts the flange  2754 . In this locked position, the edge of the locking plate  2722  around the second section  2803  cover the flange  2754  and holds the flange  2754  in place. Also, with the locking body  2720  in this locked position, the locking pin  2716  extends into the socket  2820 . The locking pin  2716  blocks movement of the locking plate in the first direction  2815  until the locking pin  2716  is withdrawn from the socket  2820 . 
     To uncouple the user interface  102  from the electrosurgical device  118 , a user engages the locking pin  2716  to slide it out of the socket  2820  to permit sliding movement of the locking body  2720 . With the locking pin  2716  withdrawn, the locking body  2720  is slid in the first direction  2815  so that the base plate  2722  moves away from the surgical device interface  2752  with the first section  2801  of the opening  2810  over the flange  2752 . The flange  2754  of the surgical device interface  2752  can now be withdrawn through the locking body  2720 , ending the connection between the surgical device interface  2752  and the slidable sleeve  612  of the user interface  102 . 
     Referring to  FIG. 29 , an illustrative method  2900  of positioning electrodes for treatment is provided. The method  2900  starts at a block  2905 . At a block  2910 , a distal end of a sheath that contains a primary electrode and a secondary electrode is moved adjacent to a target region, as described with reference to  FIGS. 6A-7B . At a block  2920 , a primary actuator, that is operably coupled with the primary electrode and a secondary actuator that is operably coupled to the secondary electrode and that is movably engaged with the primary actuator, is slid to a first position to motivate distal ends of the primary electrode and the secondary electrode relative to the target region, as described with reference to  FIGS. 14A and 14B . At a block  2930 , the secondary actuator is rotated relative to the primary actuator to cause the secondary actuator to travel independently of the primary actuator along a helical path to a second position to motivate the distal end of the secondary electrode to move independently of the primary electrode relative to the target region, as previously described with reference to  FIGS. 16A and 16B . The method  2900  ends at a block  2935 , with the electrodes now positioned. 
     Referring to  FIG. 30 , an illustrative method  3000  of motivating an implement through a helical path having a varied pitch is provided. The method  3000  starts at a block  3005 . At a block  3010 , an elongated implement is coupled at a proximal end thereof to an actuator that is movable along an axis, as described with reference to  FIG. 11 . At a block  3020 , the implement is motivated by rotatably moving the actuator through a generally helical path around the axis, the helical path having a pitch that is varied to change a distance traveled by the actuator along the axis per unit of rotation of the actuator, as described with reference to  FIGS. 16A, 16B, 22, and 23 . The method  3000  ends at a block  3025 , with the actuator having moved the implement. 
     Referring to  FIG. 31 , an illustrative method  3100  of securing devices together is provided. The method  3100  starts at a block  3105 . At a block  3110 , a locking body is positioned into an open position, where the locking body defines an opening with a first section having a first width and a second section having a second width that is smaller than the first width. The locking body is slidably mounted on one of a first device that supports a first coupling and a second device that supports a second coupling. The first section is disposed between the first coupling and the second coupling when the locking body is positioned into the open position, as described with reference to  FIG. 28 . At a block  3120 , a connection is formed by inserting the first coupling within the second coupling where one of the first and second couplings supports a flange having a flange width that is smaller than the first width and larger than the second width, as described with reference to  FIG. 28 . At a block  3130 , the locking body is repositioned into a closed position in which an edge of the locking body around the second section abuts the flange so that the coupling that supports the flange is prevented from being withdrawn from the connection, as previously described with reference to  FIG. 28 . The method  3100  ends at a block  3135 , with the couplings secured together by the locking body. 
     It will be appreciated that the detailed description set forth above is merely illustrative in nature and variations that do not depart from the gist and/or spirit of the claimed subject matter are intended to be within the scope of the claims. Such variations are not to be regarded as a departure from the spirit and scope of the claimed subject matter.