Patent Publication Number: US-2022218949-A1

Title: Control handle with device advancing mechanism

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 16/363,954 filed Mar. 25, 2019, issued as U.S. Pat. No. 11,285,295, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 15/408,361 filed Jan. 17, 2017, issued as U.S. Pat. No. 10,238,838, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 14/981,393 filed Dec. 28, 2015, issued as U.S. Pat. No. 9,545,500, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 14/060,517 filed Oct. 22, 2013, issued as U.S. Pat. No. 9,220,531, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 13/085,351 filed Apr. 12, 2011, now U.S. Pat. No. 8,562,568, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 11/863,149 filed Sep. 27, 2007, now U.S. Pat. No. 7,935,082, the entire contents of all of which are incorporated herein by reference. 
    
    
     FIELD OF INVENTION 
     The present invention relates to catheters, in particular, Electro-Physiology (EP) catheters with a control handle and a lumened catheter body. 
     BACKGROUND OF INVENTION 
     Catheter shafts are generally made of flexible, bio-compatible material, such as plastic, including polyethylene, polyester or polyamide. However, advancement into and through a patient&#39;s body and manipulation of a catheter can be difficult if the catheter shaft lacks a certain amount of stiffness. Moreover, it can be particularly challenging to provide suitable flexibility, particularly near the shaft tip, while maintaining adequate overall shaft stiffness. While there are devices available to provide or add stiffness to catheters, including stiffener wires, they are typically separate and not integrated in the catheter such that separate handling and manipulation are required. Indeed, there are few, if any, known mechanism internal to the catheter that can advance stiffening wires or other devices into, or through, EP catheters. It is therefore desirable to provide a catheter having an internal advancing mechanism that can advance stiffening wires or other devices into or through the catheter shaft. 
     SUMMARY OF THE INVENTION 
     The present invention may be directed to a wide variety of Electro-Physiology (EP) catheters (floppy shaft and/or multi-profile) that have applications for the advancement of a stiffening wire, needle or any other device. In one embodiment, there is provided a catheter with a catheter body, a tip section and a device extending through at least the catheter body, where a control handle has an advancing mechanism with a threaded member, an adjustment member, and a guided member therebetween to which the device is connected, to advance and retract the device along the catheter body as controlled by a user. 
     It is further provided that each of the threaded member and the adjustment member, both of which are generally cylindrical, are coupled to each other with the guided member between an inner surface of the adjustment member and an outer surface of the threaded member, with the guided member riding in a helical guide channel formed in the outer surface of the threaded member. The adjustment member is rotatable over the threaded member by the user to move the guided member in the channel thereby controlling the advancement and retraction of the device attached to the guided member. Rotation in one direction advances the device along the catheter body and rotation in the opposition direction retracts the device. The device may be a stiffener wire, a needle or any other device suitable for advancement and retraction in a catheter. 
     In a more detailed embodiment, there is provided a catheter having a catheter body, a tip section, a control handle comprising a threaded member, an adjustment member mounted on the threaded member and a guided member situated therebetween, and a device connected to the guided member and extending distally therefrom through the control handle, the catheter body and the tip section. The adjustment member is configured for rotation relative to the threaded member by a user to advance and retract the device. The device is wound about the threaded member and adapted to unwind and rewind as guided by the guided member in response to rotation of the adjustment member relative to the threaded member by a user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a side view of an embodiment of a catheter of the present invention. 
         FIG. 2  is a side cross-sectional view of an embodiment of a catheter body, including the junction between the catheter body and a tip section. 
         FIG. 3A  is a side cross-sectional view of an embodiment of the tip section, including the tip section, taken along a first diameter. 
         FIG. 3B  is a side cross-sectional view of an embodiment of the tip section, taken along a second diameter generally perpendicular to the first diameter. 
         FIG. 4  is a side cross-sectional view of an embodiment of a catheter handle. 
         FIG. 5  is a longitudinal cross-sectional view of the catheter body of  FIG. 2 , taken generally along line  5 - 5 . 
         FIG. 6  is a longitudinal cross-sectional view of the tip section of  FIG. 2 , taken generally along line  6 - 6 . 
         FIG. 7  is a top view of the catheter handle. 
         FIG. 8  is a side cross-sectional view of an advancing mechanism and a barrel of the control handle. 
         FIG. 8A  is a longitudinal cross-sectional view of the barrel of  FIG. 8 , taken along line a-a. 
         FIG. 8B  is a longitudinal cross-sectional view of the barrel of  FIG. 8 , taken along line b-b. 
         FIG. 8C  is a longitudinal cross-sectional view of the barrel of  FIG. 8 , taken along line c-c. 
         FIG. 8D  is a longitudinal cross-sectional view of a threaded member of  FIG. 8 , taken along line d-d. 
         FIG. 8E  is a longitudinal cross-sectional view of the threaded member of  FIG. 8 , taken along line e-e. 
         FIG. 8F  is a longitudinal cross-sectional view of an adjustment member of  FIG. 8 , taken along line f-f. 
         FIG. 8G  is a longitudinal cross-section view of the adjustment member of  FIG. 8 , taken along line g-g. 
         FIG. 9  is a cross-sectional view of a portion of the catheter tip section showing a means for anchoring the puller wire. 
         FIG. 10  is a top cross-sectional view of a preferred puller wire anchor. 
         FIG. 11  is a side cross-sectional view of a preferred puller wire anchor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , there is provided a catheter (for example, an Electro-Physiology (EP)) catheter  10  adapted to advance and retract a device  46  (for example, a wire, a needle, infusion tube or the like) in the catheter. The catheter comprises an elongated catheter body  12  having proximal and distal ends, a tip section  14  at the distal end of the catheter body  12 , and a control handle  16  having a threaded advancing mechanism  17  controllable by a user to move the device distally and proximally in the catheter body. 
     With reference to  FIGS. 2 and 5 , the catheter body  12  comprises an elongated tubular construction having a single, central or axial lumen  18 . The catheter body  12  is flexible, i.e., bendable, but substantially non-compressible along its length. The catheter body  12  can be of any suitable construction and made of any suitable material. One construction comprises an outer wall  22  made of a polyurethane or nylon. The outer wall  22  comprises an imbedded braided mesh of stainless steel or the like to increase torsional stiffness of the catheter body  12  so that, when the control handle  16  is rotated, the tip section of the catheter  10  will rotate in a corresponding manner. 
     The outer diameter of the catheter body  12  is not critical. Likewise the thickness of the outer wall  22  is not critical. The inner surface of the outer wall  22  is lined with a stiffening tube  20 , which can be made of any suitable material, for example, polyimide. The stiffening tube, along with the braided outer wall  22 , provides improved torsional stability while at the same time minimizing the wall thickness of the catheter, thus maximizing the diameter of the single lumen. The outer diameter of the stiffening tube  20  is about the same as or slightly smaller than the inner diameter of the outer wall  22 . Polyimide tubing may be very thin walled while still providing very good stiffness. This maximizes the diameter of the central lumen  18  without sacrificing strength and stiffness. Polyimide material is typically not used for stiffening tubes because of its tendency to kink when bent. However, it has been found that, in combination with an outer wall  22  of polyurethane, nylon or other similar material, particularly having a stainless steel braided mesh, the tendency for the polyimide stiffening tube  20  to kink when bent is essentially eliminated with respect to the applications for which the catheter is used 
     As shown in  FIGS. 2 and 6 , the tip section  14  comprises a short section of tubing  19  having three lumens. The tubing  19  is made of a suitable non-toxic material which can be more flexible than the catheter body  12 . One material for the tubing  19  is braided polyurethane, i.e., polyurethane with an embedded mesh of braided stainless steel or the like. The outer diameter of the tip section  14 , like that of the catheter body  12 . The size of the lumens is not critical. In one embodiment, the first lumen  30  and second lumen  32  are generally about the same size, with the third lumen  34  having a slightly larger diameter. 
     One embodiment of means for attaching the catheter body  12  to the tip section  14  is illustrated in  FIG. 2 . The proximal end of the tip section  14  comprises an outer circumferential notch  24  that receives the inner surface of the outer wall  22  of the catheter body  12 . The tip section  14  and catheter body  12  are attached by glue or the like. In the arrangement shown, a spacer  52  lies within the catheter body  12  between the distal end of the stiffening tube  20  and the proximal end of the tip section  14 . The spacer  52  can be made of a material which is stiffer than the material of the tip section  14 , e.g., polyurethane, but not as stiff as the material of the stiffening tube  20 , e.g., polyimide. A spacer made of Teflon® may be used in one embodiment. The spacer  52  may have an outer and inner diameter about the same as the outer and inner diameters of the stiffening tube  20 . The spacer  52  provides a transition in flexibility at the junction of the catheter body  12  and catheter tip  14 , which allows the junction of the catheter body  12  and tip section  14  to bend smoothly without folding or kinking. 
     The spacer  52  is held in place by the stiffening tube  20 . The stiffening tube  20 , in turn, is held in place relative to the outer wall  22  by glue joints at the proximal end of the catheter body  12 . 
     As shown in  FIGS. 2 and 5 , extending through the single lumen  18  of the catheter body  12  are lead wires  40 , the device  46 , a sensor cable  74 , and a compression coil  44  through which a puller wire  42  extends. A single lumen  18  catheter body compared to a multi-lumen body can permit better tip control when rotating the catheter  10 . The single lumen  18  permits the lead wires  40 , the device  46 , the sensor cable  74 , and the puller wire  42  surrounded by the compression coil  44  to float freely within the catheter body. If such components were restricted within multiple lumens, they can tend to build up energy when the handle  16  is rotated, resulting in the catheter body  12  having a tendency to rotate back if, for example, the handle is released, or if bent around a curve, to flip over, either of which are often undesirable performance characteristics. 
     The puller wire  42  is anchored at its proximal end to the control handle  16  and anchored at its distal end to the tip section  14 . The puller wire  42  is made of any suitable metal, such as stainless steel or Nitinol, and is coated with Teflon® or the like. The coating imparts lubricity to the puller wire  42 . 
     The compression coil  44  extends from the proximal end of the catheter body  12  to the proximal end of the tip section  14 . The compression coil  44  is made of any suitable metal, such as stainless steel. The compression coil  44  is tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of the compression coil  44  is slightly larger than the diameter of the puller wire  42 . The Teflon® coating on the puller wire  42  allows it to slide freely within the compression coil  44 . Along its length, the outer surface of the compression coil  44  is covered by a flexible, non-conductive sheath  26  to prevent contact between the compression coil  44  and any of the lead wires  40 , the device  46  or sensor cable  74 . A non-conductive sheath  26  made of polyimide tubing can be provided. 
     The compression coil  44  is anchored at its proximal end to the proximal end of the stiffening tube  20  in the catheter body  12  by a glue joint and at its distal end to the tip section  14  at a location distal to the spacer  52  by glue joint  50 . Both glue joints may comprise polyurethane glue or the like. The glue may be applied by means of a syringe or the like through a hole made between the outer surface of the catheter body  12  and the single lumen  18 . Such a hole may be formed, for example, by a needle or the like that punctures the wall of the catheter body  12  and the stiffening tube  20  which is heated sufficiently to form a permanent hole. The glue is then introduced through the hole to the outer surface of the compression coil  44  and wicks around the outer circumference to form a glue joint about the entire circumference of the compression coil  44 . 
     As shown in  FIGS. 2, and 6 , the puller wire  42  extends into the second lumen  32  of the tip section  14 . The puller wire  42  is anchored to a tip electrode  36  or to the side of the catheter tip section  14 . Within the tip section  14 , and distal to the glue joint  51 , the turns of the compression coil are expanded longitudinally. Such expanded turns are both bendable and compressible. The puller wire  42  extends through the expanded turns then into a plastic, such as Teflon®, sheath  81  ( FIG. 3B ), which prevents the puller wire  42  from cutting into the wall of the tip section  14  when the tip section  14  is deflected. 
     As shown in  FIG. 3B , the distal end of the puller wire  42  may be anchored to the tip electrode  36  by solder or the like, as shown in  FIG. 2 b    or to the side wall of the tip section  14 . If attached to the side wall, an embodiment comprising an anchor  80  fixedly attached to the distal end of the puller wire  42  is be used, as illustrated in  FIGS. 9-11 . In such an embodiment, the anchor is formed by a metal tube  82 , e.g., a short segment of hypodermic stock, which is fixedly attached, e.g., by crimping, to the distal end of the puller wire  42 . The tube  82  has a section which extends a short distance beyond the distal end of the puller wire  42 . A cross-piece  84  made of a small section of stainless steel ribbon or the like is soldered or welded in a transverse arrangement to the distal end of the tube  82 , which is flattened during the operation. This creates a T-bar anchor  80 . A notch  86  is created in the side of the catheter tip section  14  resulting in an opening into the second lumen  32  carrying the puller wire  42 . The anchor  80  lies within the notch  86 . Because the length of the ribbon forming the cross-piece  84  is longer than the diameter of the opening into the second lumen  32 , the anchor  80  cannot be pulled completely into the second lumen  32 . The notch  86  is then sealed with polyurethane or the like to give a smooth outer surface. 
     With reference to  FIGS. 3A and 3B , at the distal end of the tip section  14  is a tip electrode  36 . In the illustrated embodiment, the tip electrode  36  has a diameter about the same as the outer diameter of the tubing  19 . The tip electrode  36  is connected to the tubing  19  by means of a plastic housing  21 , which can be made of polyetheretherketone (PEEK). The proximal end of the tip electrode  36  is notched circumferentially and fits inside the distal end of the plastic housing  21  and is bonded to the housing  21  by polyurethane glue or the like. The proximal end of the plastic housing  21  is bonded with polyurethane glue or the like to the distal end of the tubing  19  of the tip section  14 . 
     Mounted on the distal end of the plastic housing  21  is a ring electrode  38 . The ring electrode  38  is slid over the plastic housing  21  and fixed in place by glue or the like. If desired, additional ring electrodes may be used and can be positioned over the plastic housing  21  or over the flexible tubing  19  of the tip section  14 . 
     The tip electrode  36  and ring electrode  38  are each connected to separate lead wires  40 . The lead wires  40  extend through the third lumen  34  of tip section  14 , the catheter body  12 , and the control handle  16 , and terminate at their proximal end in an input jack (not shown) that may be plugged into an appropriate monitor (not shown). If desired, the portion of the lead wires  40  extending through the catheter body  12 , control handle  16  and proximal end of the tip section  14  may be enclosed or bundled within a protective tube or sheath. 
     The lead wires  40  are attached to the tip electrode  36  and ring electrode  38  by any conventional technique. Connection of lead wire  40  to the tip electrode  36  can be accomplished by weld  43 , as shown in  FIG. 3B . Connection of a lead wire  40  to a ring electrode  38  can be accomplished by first making a small hole through the plastic housing  21 . Such a hole can be created, for example, by inserting a needle through the plastic housing  21  and heating the needle sufficiently to form a permanent hole. A lead wire  40  is then drawn through the hole by using a microhook or the like. The ends of the lead wire  40  are then stripped of any coating and soldered or welded to the underside of the ring electrode  38 , which is then slid into position over the hole and fixed in place with polyurethane glue or the like. 
     In the illustrated embodiment, a temperature sensing means is provided for the tip electrode  36  and, if desired, the ring electrode  38 . Any conventional temperature sensing means, e.g., a thermocouple or thermistor, may be used. With reference to  FIG. 3B , one temperature sensing means for the tip electrode  36  comprises a thermocouple formed by an enameled wire pair. One wire of the wire pair is a copper wire  41 , e.g., a number  40  copper wire which acts not only as part of the thermocouple, but as the electrode lead. The other wire of the wire pair is a construction wire  45 , e.g., a number  40  construction wire, which gives support and strength to the wire pair. The wires  41  and  45  of the wire pair are electrically isolated from each other except at their distal ends where they contact and are welded or soldered to the tip electrode  36 . Because it is desirable to monitor the temperature of the tip electrode  36  at a site adjacent the distal end of the optic fiber  46 , the thermocouple with a blind hole in the tip electrode  36  is fixed to the tip electrode  36  at the distal end of the blind hole as shown. The wires  41  and  45  extend through the third lumen  34  of the tip section  14  and through the central lumen  18  of the catheter body  12  into the control handle  16 . 
     In the illustrated embodiment, an electromagnetic sensor  72  is contained within the distal end of the tip section  14 . The electromagnetic sensor  72  is connected by means of electromagnetic sensor cable  74 , which extends through the third lumen  34  of the tip section  14  and through the catheter body  12  into the control handle  16 . The electromagnetic sensor cable  74  comprises multiple wires encased within a plastic covered sheath. In the control handle  16 , the wires of the sensor cable  74  are connected to a circuit board  64 . The circuit board  64  amplifies the signal received from the electromagnetic sensor and transmits it to a computer in a form understandable by the computer. Also, because the catheter is designed for single use only, the circuit board contains an EPROM chip which shuts down the circuit board after the catheter has been used. This prevents the catheter, or at least the electromagnetic sensor, from being used twice. A suitable electromagnetic sensor is described, for example, in U.S. Pat. No. 4,391,199, which is incorporated herein by reference. An electromagnetic mapping sensor  72  is manufactured by Biosense Ltd. Israel and marketed under the trade designation NOGA. 
     The electrode lead wires  40 , thermocouple wires  41  and  45 , and electromagnetic sensor cable  74  and any other components or device, including the device  46 , are allowed longitudinal movement within the catheter body  12 . The wires  40 ,  41  and  45  and cable  74  are allowed such movement so that they do not break when the tip section  14  is deflected. The device  26  is allowed such movement so that it can be advanced and retracted in accordance with a feature of the present invention. To provide for such lengthwise movement, there are tunnels provided through the glue joint  50  in the catheter body  12  ( FIG. 2 ), which fixes the proximal end of the compression coil  44  inside the catheter body  12 . The tunnels are formed by transfer tubes  27 , made of short segments of polyimide tubing in one embodiment. In the embodiment shown in  FIG. 2 , there is one transfer tube  27  for the wires  40 ,  41  and  45  and the electromagnetic sensor cable  74  and a second transfer tube  27  for the device  46 . It is understood that the number of transfer tubes may vary as desired. 
     Longitudinal movement of the puller wire  42  relative to the catheter body  12 , which results in deflection of the tip section  12 , is accomplished by suitable manipulation of the control handle  16 . As shown in  FIG. 4 , the distal end of the control handle  16  comprises a piston  54  with a thumb control  56  for manipulating the puller wire  42 . The proximal end of the catheter body  12  is connected to the piston  54  by means of a shrink sleeve  28 . 
     The puller wire  42 , lead wires  40 , thermocouple wires  41  and  45 , device  46  and electromagnetic sensor cable  74  extend through the piston  54 . The piston  54  lies within a barrel  57  of the control handle. The barrel  57  is generally solid having a piston chamber for receiving the piston  54 . Extending proximally from the piston chamber are two longitudinal tunnels  58  and  60  and a transverse hole  59  for receiving the anchor pin  87 . The first longitudinal tunnel  58  is in communication with the transverse hole  59 . The lead wires  40 , thermocouple wires  41  and  45 , and sensor cable  74  extend through the first tunnel  58 . The puller wire  42  also extends through the first tunnel  58  and is anchored to the anchor pin  87  in the transverse hole  59 . The device  46  extends through the second tunnel  60 . Between the distal end of the tunnels  58  and  60  and the proximal end of the piston  54 , chamber  62  provides additional space to avoid undesirable bending of the components extending therethrough. The electromagnetic sensor cable  74  connects to the circuit board  64  in the control handle  16 . Wires  90  connect the circuit board  64  to a computer and imaging monitor (not shown). 
     The device  46 , for example, a stiffener wire, a needle, or the like, extends through the control handle  16  and catheter body  12  and into the first lumen  30  of the tip section  14 . In accordance with a feature of the present invention, the device  46  can be moved distally and proximally within catheter body by manipulation of the control handle  16 , as discussed further below. Where the device is a stiffener wire or the like, the stiffener wire can be controlled to slide distally and proximally within the catheter body and/or tip section. Where the device  46  is a needle or the like, its distal end can be advanced beyond the distal end of the tip section to reach and contact tissue separately from the tip section, and then retracted back into tip section. As understood by one of ordinary skill in the art, the device  46  is not limited to stiffener wires and needles, but includes any structure that may be advanced within a catheter. 
     In the illustrated embodiment of  FIGS. 4, 7 and 8 , the control handle  16  has a second barrel  55  proximal the barrel  57  for an extended control handle configuration. The device  46  extends proximally into the control handle through the piston  54  in the distal barrel  57 , and through a distal end  100  of the proximal barrel  55  which has an opening or notch  102  in its general circular cross section ( FIG. 5 a   ) to accommodate the device  46 . In the illustrated embodiment, the advancing mechanism  17 , as means for allowing the advance and retraction of the device  46  in accordance with a feature of the present invention, is mounted on a proximal end  104  of the proximal barrel  55 . 
     In the illustrated embodiment, the device advancing mechanism  17  includes a generally cylindrical threaded guide member  106 , a generally cylindrical adjustment member  108  mounted thereon, and a guided member  110  (e.g., a slug or pin) situated between an outer surface  114  of the member  106  and an inner surface  109  of the member  108 . The guided member slides in a helical guide channel  112 , with a generally straight distal portion  116  and a generally straight proximal portion  118 , all formed on the outer surface  114  of the guide member  106 . In the illustrated embodiment, the helical guide channel  112  winds about the guide member  106  for approx. 4½ turns, such that the distal channel portions  116  and  118  are generally diametrical of each other (see  FIGS. 8 d  and 8 e   ). 
     The generally cylindrical adjustment member  108  is sized such that its interior is in close conformity with the member  106  to receive the latter in an overlapping, generally co-axial configuration. In that regard, the guide member  106  has protrusions  120  that lock with a recessed ring  122  formed in the inner surface  109  of the proximal end of the adjustment member  108 , for a snap-fit coupling. Radial alignment for proper assembly of the advancement mechanism is accomplished when an elongated slot  126  formed in the inner surface  109  of the distal end of the member  108  receives the guided member  110  situated in the channel  112  of the member  106 . As better illustrated in  FIG. 7 , the width of the slot is in close conformity to the width of the guided member  110  so that rotation of the adjustment member  108  (shown in broken lines) effectively moves the guided member  110  in the channel  112  of the guide member  106 . Anchored to the guided member  110  is the proximal end of the device  46 , the adjacent distal portion of which is wound about the guide member  106  in the guide channel  112  and extends into the interior of the barrel  55  from the generally straight distal channel portion  116  on the member  106 . 
     As shown in  FIG. 8 , the distal end of the guide member  106  is inserted into an enlarged conforming opening  130  at the proximal end of the barrel  55  which has a generally cylindrical hollow interior  132 . With coupling of the members  108  and  106 , the advancement mechanism  17  forms a passage  133  that communicates with the interior  132  of the barrel  55  and allows components, such as the lead wires  40 , the electromagnetic cable  74 , and the thermocouple wires  41  and  45  extending proximally through the control handle to pass through the barrel  55 . While these components extend through the interior  132  of the barrel  55 , the device  46  extends through similarly except toward the proximal end of the barrel  55  which is provided with a passage  138  dedicated to the device  46 . Advantageously, the passage  138  is configured for alignment with the generally straight distal guide channel  116  of the guide member  106 , so that the device  46  can extend from the interior  132 , through the passage  138  and be wound onto the member  106 . 
     To assemble the advancing mechanism  17  on the control handle, the guided member  110  with the proximal end of the device  46  anchored thereto is placed in the channel  112  with the adjacent distal portion of the device  46  wounded in the channels  112  and  116  distally therefrom. The distal end of the member  106  is inserted into the barrel  55 . The member  108  is inserted distally over the member  106 , with the slot  126  aligned with the guided member  110 , until the protrusions  120  of the member  106  lock in the ring recess  122  of the member  108  and the distal end of the member  108  generally abuts with the proximal end of the barrel  55 . 
     In operation to accomplish the advancement and retraction of the device  46 , the advancing mechanism  17  can be manipulated by the user through rotation of the adjustment member  108  by means of a knob  140  formed on an outer surface at the proximal end of the member  108 . As the user rotates the knob (e.g. clockwise in the illustrated embodiment), the slot  126  on the inner surface  109  is rotated about the longitudinal axis of the member  108  to drive the guided member  110  helically along the guide channel  112  in the distal direction, which in turn distally pushes the device  46  connected to the guided member  110 . Such advancement can continue until the guided member  110  reaches the generally straight distal guide channel  116 , at which location the distal end of the slot  126  blocks further distal movement of the guided member  110 . 
     To retract the device  46 , the user rotates the knob  140  in the opposite direction (e.g., counterclockwise in the illustrated embodiment) which causes the slot  126  to drive the guided member  110  helically in the proximal direction, which in turn draws the device  46  proximally. This retraction can continue until the guided member  110  reaches the generally straight proximal guide channel  116 , at which location the proximal end of the slot  126  prevents further proximal movement of the guided member  110 . 
     It is understood by one of ordinary skill in the art that an overlapping longitudinal region between the slot  126  and the helical guide channel  112  defines the possible travel distance of the guided member  110  and thus the advancement/retraction distance of the device  46 , and therefore variations in either or both of the length of the slot and the longitudinal spread of the channel  112  as between channels  116  and  118 , and/or the degree of overlap can alter the travel distance of the guided member  110  and the maximum advancement/retraction distance of the device  46 . It is further understood that other variations, including a change in the diameter of the guiding member  106  (which changes the circumference of the helical channel  112  and the maximum advancement/retraction distance) and/or the number of windings or turns of the helical channel can also alter the travel distance and maximum advancement/retraction distance. 
     The illustrated embodiment of  FIG. 3A  discloses a needle as the device  46 , which can be advance beyond the distal end of the tip electrode  36 . Clearly, as understood by one of ordinary skill in the art, the device can be other instruments or structures that need not extend beyond the distal tip of the tip electrode when advanced to its maximum distal position. Indeed, the amount of advancement and retraction desired or appropriate can be achieved with modifications of the advancement mechanism, including but not limited to the aforementioned variations. 
     The preceding description has been presented with reference to presently preferred embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. For example, the advancing mechanism may be integrated anywhere along the control handle. User interface may be modified to allow for a linear motion deflection knob rather than the rotational knob mentioned above. 
     Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope.