Patent Publication Number: US-2022226039-A1

Title: Rf ablation systems and methods including a cannula with contacts or a connector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 63/138,092, filed Jan. 15, 2021, which is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure is directed to the area of radiofrequency (RF) ablation systems and methods of making and using the systems. The present disclosure is also directed to RF ablation system and methods that include a cannula with contacts or a connector, as well as methods of making and using the same. 
     BACKGROUND 
     Radiofrequency (RF) generators and electrodes can be used for pain relief or functional modification. Radiofrequency ablation (RFA) is a safe, proven means of interrupting pain signals, such as those coming from irritated facet joints in the spine, genicular nerves in the knee, and femoral and obturator nerves in the hip. Radiofrequency current is used to heat up a small volume of nerve tissue, thereby interrupting pain signals from that specific area. Radiofrequency ablation is designed to provide long-lasting pain relief. 
     For example, an RF electrode can be positioned near target tissue and then used to heat the target tissue by RF power dissipation of the RF signal output in the target tissue. Temperature monitoring of the target tissue by a temperature sensor in the electrode may be used to control the process. 
     BRIEF SUMMARY 
     One aspect is an RF ablation cannula that includes a cannula shaft; an active tip as part of, or coupled to, the cannula shaft; a cannula hub coupled to the cannula shaft, the cannula hub including at least a first cannula contact and a second cannula contact, wherein the first cannula contact is electrically coupled to the active tip; and a wire extending along the cannula shaft and attached to the active tip or cannula shaft to form a thermocouple, wherein the wire is electrically coupled to the second cannula contact. 
     In at least some aspects, the cannula hub includes a spacer disposed between the first and second cannula contacts. In at least some aspects, the first cannula contact differs from the second cannula contact in size or shape. 
     In at least some aspects, the cannula shaft is hollow and the either the cannula shaft or active tip has an opening. In at least some aspects, the cannula hub defines a port for injection of fluid into the cannula hub, through the hollow cannula shaft, and out the opening. In at least some aspects, the RF ablation cannula further includes an injection tube extending from the cannula hub, wherein the injection tube defines a port for injection of fluid into the injection tube, through the cannula hub, through the hollow cannula shaft, and out the opening. 
     In at least some aspects, the active tip is sharp. In at least some aspects, the cannula shaft is conductive, the cannula further including insulation extending along the cannula shaft from the cannula hub to the active tip. In at least some aspects, the wire is disposed over, or embedded within, the insulation. 
     Another aspect is an RF ablation system that includes any of the RF ablation cannulas described above and a coupler that includes a first coupler contact and a second coupler contact configured for attaching and electrically coupling to the first contact and second contact of the RF ablation cannula and a cable electrically coupled to the first and second coupler contacts and terminating in a connector configured to couple to an RF generator. 
     In at least some aspects, the coupler further includes a coupler clip with the first and second coupler contacts extending from the coupler clip, wherein the coupler clip is configured and arranged to facilitate attachment of the coupler to the cannula hub of the RF ablation cannula. In at least some aspects, the coupler clip includes a first wing from which the first and second coupler contacts extend, a second wing, and an arm attached to, and between, the first and second wings. In at least some aspects, the arm is biased to bring the first and second contacts toward each other. 
     In at least some aspects, the first and second cannula contacts are ring contacts and the first and second coupler contacts are partial ring contacts configured to circumferentially engage a portion of the first or second cannula contacts, respectively. In at least some aspects, the first and second cannula contacts have different shapes or sizes and the first and second coupler contacts have shapes and sizes corresponding to the first or second cannula contacts, respectively. 
     In at least some aspects, the RF ablation system further includes an RF generator configured to electrically couple to the coupler. 
     A further aspect is an RF ablation cannula that includes a cannula shaft; an active tip as part of, or coupled to, the cannula shaft; a cannula hub coupled to the cannula shaft, the cannula hub including a cannula connector, the cannula connector including at least a first connector contact and a second connector contact, wherein the first connector contact is electrically coupled to the active tip; and a wire extending along the cannula shaft and attached to the active tip or cannula shaft to form a thermocouple, wherein the wire is electrically coupled to the second connector contact. 
     In at least some aspects, the cannula shaft is conductive, the cannula further including insulation extending along the cannula shaft from the cannula hub to the active tip. In at least some aspects, the wire is disposed over, or embedded within, the insulation. 
     Yet another aspect is an RF ablation system that includes any of the RF ablation cannulas of the preceding two paragraphs; an RF generator; and a cable configured to electrically couple the RF generator to the cannula connecter of the RF ablation cannula. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified. 
       For a better understanding of the present invention, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings, wherein: 
         FIG. 1  is a schematic side view of components of one embodiment of a conventional RF ablation system; 
         FIG. 2  is a schematic perspective view of one embodiment of a cannula with contacts; 
         FIG. 3  is a schematic perspective view of one embodiment of a coupler for coupling to the cannula of  FIG. 2 ; 
         FIG. 4  is a schematic perspective view of the coupler of  FIG. 3  coupled to the cannula of  FIG. 2 ; 
         FIG. 5  is a schematic perspective close-up view of a distal portion of the cannula of  FIG. 2 ; 
         FIG. 6A  is schematic bottom view of the coupler of  FIG. 3  coupled to the cannula of  FIG. 2 ; 
         FIG. 6B  is schematic perspective close-up view of the coupler of  FIG. 3  coupled to the cannula of  FIG. 2 ; 
         FIG. 7A  is a schematic perspective view of one embodiment of a cannula with contacts and an injection port, as well as a syringe; 
         FIG. 7B  is a schematic perspective view of the syringe inserted into the injection port of the cannula of  FIG. 7A ; 
         FIG. 8  is a schematic perspective view of one embodiment of a cannula with contacts and an injection tube with an injection port; 
         FIG. 9A  is a schematic perspective close-up view of one embodiment of a portion of a cannula with contacts and a connector in the cannula hub; 
         FIG. 9B  is a schematic perspective view of the cannula of  FIG. 10A  with an injection tub extending from the cannula hub; and 
         FIG. 10  is a schematic side view of one embodiment of a portion of a cannula with a side electrode extending from the cannula shaft. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is directed to the area of radiofrequency (RF) ablation systems and methods of making and using the systems. The present disclosure is also directed to RF ablation system and methods that include a cannula with contacts or a connector, as well as methods of making and using the same. 
       FIG. 1  illustrates one embodiment of a conventional RF ablation system  100  that includes a RF generator  102 , a RF electrode  104 , a cannula  106 , a ground pad  107 , and an optional extension cable  109 . The cannula  106  includes a cannula hub  108 , an insulated shaft  110 , and an active tip  112 . The insulated shaft  110  is hollow for receiving the RF electrode  104 . When inserted, the RF electrode  104  contacts, and energizes, the active tip  112  of the cannula  106  to produce RF ablation. The RF electrode  104  includes an electrode shaft  114 , an electrode hub  116 , a cable  118  that is electrically coupled to the electrode shaft  114 , and a connector  120  for connecting to a port  122  of the RF generator  102  to energize the electrode shaft  114  via the cable  118  and connector  120 . The optional adapter or extension  109  includes a cable  119  and connectors  117   a ,  117   b  for coupling the RF electrode  104  to the RF generator  102 . It will be recognized that other RF ablation systems utilize the RF electrode  104  for ablation instead of, or in addition to, the cannula  106 . 
     The RF generator  102  can include one or more ports  122  and at least one screen  130 . In at least some embodiments, each port  122  is associated with a portion of the screen  130  (or a different screen) and can receive the connector  120  from an RF electrode  104 . Information such as current, voltage, status, or the like or any combination thereof can be displayed on the screen  130 . In at least some embodiments, each port  122  corresponds to an independent channel for operating a RF electrode  104 . The RF generator  102  also includes a ground port  121  for attachment of the ground pad  107 . 
     Examples of RF generators and RF ablation systems and methods of making and using the RF generators and RF ablation systems can be found at, for example, U.S. Pat. Nos. 9,717,552; 9,956,032; 10,111,703; 10,136,937; 10,136,942; 10,136,943; 10,194,971; 10,342,606; 10,363,063; 10,588,687; 10,631,915; 10,639,098; and 10,639,101 and U.S. Patent Application Publications Nos. 2014/0066917; 2014/081260; and 2014/0121658, all of which are incorporated herein by reference in their entireties. 
     One failure mode for the convention RF electrode is the electrode shaft breaking during insertion or otherwise. In addition, the RF electrode often must be removed to inject fluid through the cannula to the treatment site. 
     As disclosed herein, the cannula can act as an RF electrode by placing contacts on the cannula for coupling to the RF generator and including a coupler to couple the cannula to the RF generator.  FIG. 2  illustrates one embodiment of a cannula  206  that includes a cannula hub  208 , a shaft  210 , an active tip  212 , cannula contacts  230 , and a temperature sensing element, such as a thermocouple  232 .  FIG. 3  illustrates one embodiment of the coupler  240  that includes coupler contacts  242 , a coupler clip  244 , and a cable  246  with a connector (such as connector  120  of  FIG. 1 ) for connecting to the RF generator  102  ( FIG. 1 ) or an extension  109  ( FIG. 1 ).  FIG. 4  illustrates the coupler  240  attached to the cannula  206  so that the coupler contacts  242  engage and electrically couple to the cannula contacts  230 . It will be understood that the cannula  206  and coupler  240  can be used with the RF generator  102 , ground pad  107 , and optional extension cable  109  of  FIG. 1  or any other suitable components of an RF ablation system. 
     In at least some embodiments, the shaft  210  of the cannula  206  is hollow and optionally has at least one opening (not shown) at the active tip  212  or along the shaft. The active tip  212  of the cannula  206  is electrically coupled to one of the cannula contacts  230 . In at least some embodiments, the shaft  210  and active tip  212  are formed of biocompatible material, such as, for example, stainless steel, titanium, nitinol, conductive epoxy, conductive polymers, or the like or any other suitable biocompatible conductive material. In at least some embodiments, the active tip  212  can be an exposed distal portion of the shaft  210 . In at least some embodiments, a portion of the shaft  210  is covered by an insulation  235 , such as a plastic or polymeric material (for example, heat shrink tubing), between the cannula hub  208  and the active tip  212 . 
     In at least some embodiments, the active tip  212  of the cannula  206  can have a sharpened region  233  ( FIG. 5 ) so that cannula can act as a needle. In other embodiments, the active tip  212  of the cannula can be blunt. The cannula  206  or the active tip  212  (or both) can be straight or curved. In at least some embodiments, the active tip  212  can be dimpled or contain other features to increase echogenicity or surface area. The cannula  206  or active tip  212  can have any suitable length. The cannula  206  can have any suitable gauge or diameter. 
       FIG. 5  is a close-up view of the active tip  212  and surrounding portions of the cannula  206 . In at least some embodiments, the temperature sensing element is a thermocouple  232  formed by a wire  234  attached (for example, welded) to the active tip  212  (or other portion of the shaft  210 ) of the cannula  206 . The wire  234  is made of different material (for example, constantan or the like) than the active tip  212  (or other portion of the shaft  210 ) of the cannula. In at least some embodiments, the wire  234  extends along the shaft  210  of the cannula  206 . In at least some embodiments, the wire  234  is insulated with a distal portion of the wire exposed by removal of the insulation and attached to the active tip  212  (or other portion of the shaft  210 ) of the cannula. In at least some embodiments, the wire  234  is insulated from the shaft  210  by the insulation  235  on at least a portion of the shaft. In at least some embodiments, the wire  234  can be embedded in, or covered by, the insulation  235 . In other embodiments, the wire  234  is disposed over the insulation  235 . In at least some embodiments, the wire  234  can be attached to the cannula  206  using adhesive (in at least some embodiments, an electrically insulative adhesive). 
     The thermocouple  232  illustrated in  FIGS. 2, 4, and 5  is particularly useful as the thermocouple is disposed near the tissue that is to be ablated or stimulated by the active tip  212  of the cannula  206 . In some embodiments, the welding point of the wire  234  of the thermocouple  232  can be covered by the insulation  235 , an adhesive, or other coating that is thermally conductive to produce a shielded thermocouple that is not in direct contact with the tissue. In other embodiments, the welding point of the wire  234  of the thermocouple  232  is in direct contact with the tissue when the cannula  230  is positioned. 
     Returning to  FIGS. 2 and 4 , in at least some embodiments, the cannula contacts  230  are ring contacts that extend around the circumference of the shaft  210  or cannula hub  208 . In at least some embodiments, ring contacts can be advantageous because the coupler  240  can be attached to the ring contacts without a particular rotational orientation. In other embodiments, the cannula contacts  230  can have a shape other than a ring including, but not limited to, a partial ring, a contact pad, a square, a rectangle, a hexagon, an octagon, any other polygon, any other regular or irregular shape, or the like or any combination thereof. In at least some embodiments, the cannula contacts  230  differ from each other in one or more aspects such as, for example, size, diameter, width, color, shape, profile, material, or the like or any combination thereof so that the user can determine whether the coupler  240  is coupled correctly to the cannula contacts  230  (i.e., that each of the coupler contacts  242  couples to the correct cannula contact  230 .) In at least some embodiments, the one or more aspects of difference are visible. In at least some embodiments, the one or more aspects of difference prevent or substantially hinder attachment of the coupler  240  incorrectly. 
     In at least some embodiments, one of the cannula contacts  230  is electrically coupled (for example, attached via a weld, solder, or the like) to the wire  234  of the thermocouple  232 . The other cannula contact is electrically coupled to the cannula  206  (for example, attached via a weld, solder, or the like and optionally using a wire (not shown) between the cannula contact and the cannula) to energize the active tip  212 . In at least some embodiments, one of the cannula contacts  230  is electrically coupled to the shaft  210  of the cannula  206  if the shaft is made of an electrical material. In at least some embodiments, one of the cannula contacts  230  is electrically coupled to the active tip  212  using a wire (not shown) extending along the shaft  210  (either along the exterior of the shaft or in a lumen within the shaft) to the active tip. 
     In at least some embodiments, the cannula contacts  230  are separated by a spacer  236 . In at least some embodiments, the spacer  236  has a larger diameter than the cannula contacts  230  to prevent inadvertent improper coupling or slipping of the coupler contacts  242 . 
     RF energy is provided to the active tip  212  of the cannula  206  using one of the cannula contacts  230  with the return path for current being the ground pad  107  or another RF electrode or cannula. In at least some embodiments, the temperature sensing element uses both of the cannula contacts  230  as the thermocouple  232  includes the junction between the wire  232  and the active tip  212  (or shaft  210 ) of the cannula  206 . 
     Returning to  FIG. 3 , the coupler  240  includes coupler contacts  242 , coupler clip  244 , cable  246 , and a connector (not shown). In at least some embodiments, the coupler  240  is reusable. In at least some embodiments, the coupler  240  is autoclavable. In at least some embodiments, the coupler contacts  242  have a shape that is complementary to the shape of the cannula contacts  230 . For example, as illustrated in  FIG. 3 , the coupler contacts  242  can have a partial ring shape to fit around (for example, circumferentially engage) a portion of ring-shaped cannula contacts  230 . In at least some embodiments, the inner diameter of the coupler contacts  242  is the same as the outer diameter of the cannula contacts  230 . 
       FIG. 6A  illustrates a bottom view of the coupler  240  showing one of the coupler contacts  242  coupled to one of the cannula contacts  230  and  FIG. 6B  is a close-up, side view of this arrangement. In this embodiment, each of the coupler contacts  242  extends into the coupler clip  244  with a shank  243  extending from a contact portion  242   a  of the coupler contact into one wing  248   a  of the coupler clip. Any other suitable arrangement for coupling the coupler contacts  242  to the coupler clip  244  can be used. In at least some embodiments, the opposing wing  248   b  of the coupler clip  244  can include a bar  249 . In at least some embodiments, an insulative material  250  (which may also be flexible) is disposed around the bar  249  and shank  243  for gripping by a user. In at least some embodiments, the bar  249  includes prongs  251  that flank the spacer  236  when the coupler clip  244  is coupled to the cannula hub  208 , as illustrated in  FIG. 6B . In at least some embodiments, the two coupler contacts  242  also flank the spacer  236 . 
     In at least some embodiments, an arm  252  connects wings  248   a ,  248   b  at a position spaced apart from end portions  245   a ,  245   b ,  247   a ,  247   b  of the wings. In at least some embodiments, the arm  252  is sufficiently flexible or stretchable (or both) to allow a user to grasp distal end portions  245   a ,  245   b  of the wings  248   a ,  248   b  and increase the separation between the proximal end portions  247   a ,  247   b  of the wings to facilitate attachment and detachment of the coupler clip  244  to/from the cannula contacts  230  on the cannula hub  208 . In at least some embodiments, the arm  252  is biased to draw the proximal end portions  247   a ,  247   b  of the wings  248   a ,  248   b  together when force is not applied to the distal end portions  245   a ,  245   b  of the wings. In at least some embodiments, the material of the arm  252  provides biasing. In at least some embodiments, the arm  252  includes a biasing element such as a spring or the like to provide biasing. 
     In at least some embodiments, the cannula hub  208  includes an injection port  260 , as illustrated in  FIGS. 7A and 7B . A syringe  262  or other source of fluid can be coupled to the injection port  260  to inject fluid through the cannula hub  208  and cannula shaft  235  and out an opening in the active tip  212  (or elsewhere along the shaft  210 ). 
     In at least some embodiments, the cannula hub  208  includes an injection tube  264  extending from the cannula hub  208  with the injection port  260  at the end of the injection tube, as illustrated in  FIG. 8 . In at least some embodiments, the injection tube  264  includes a valve  266  for opening or closing the tube. 
       FIGS. 9A and 9B  illustrate another embodiment of a cannula  206  in which a connector  270  is disposed in the cannula hub  208 . The connector  270  is an alternative to the coupler  242  and includes connector contacts  272  (such as pins, as illustrated in  FIG. 9A , or contact pads or the like or any combination thereof) that couple to the cannula contacts  230  or directly to the wire  234  of the thermocouple  232  and the cannula  206  to energize active tip  212 . In at least some embodiments that include connector  270 , the cannula hub  208  does not include cannula contacts  230 . The connector  270  can be coupled to the RF generator  102  ( FIG. 1 ) using the extension  109  ( FIG. 1 ) or any other suitable connection components or technique. Optionally, the cannula  206  can include an injection port  260  ( FIGS. 7A and 7B ) or an injection tube ( FIG. 8  and  FIG. 9B ). 
       FIG. 10  illustrates an alternative active tip  212  of cannula  206  which includes a side electrode  280 . In at least some embodiments, the side electrode  280  can be a stylet that is inserted through the injection port  260  or other port on the cannula hub  208 . In at least some embodiments, the side electrode  280  can be permanently disposed in the cannula  206  and extended from, or retracted into, the shaft  210  (or other portion) of the cannula  206 . Arrangements and methods for extending or retracting the side electrode  280  can be found in, for example, U.S. Provisional Patent Application Ser. No. 63/131,260 (entitled “RF Ablation Systems and Methods Using an Integrated Cannula and Electrode”, Attorney Docket No. BSNC-1-718.0), filed Dec. 28, 2020. 
     An example of using the cannula  206  includes placing the cannula in a patient and connecting the coupler  240  (or connector  270 ) to the RF generator  102  and the cannula. If desired, the clinician can perform motor testing or stimulation using the cannula  206  and the RF generator  102 . Also, if desired, the clinician can inject anesthetic or other fluid into the port  260 , if available, in the cannula hub  208  or the cannula tube  262  attached the cannula hub. The cannula  206  can be used to perform RF ablation with the coupler  240  coupled to the RF generator  102  and the cannula. After treatment, the cannula  206  can be removed from the patient. 
     The above specification provides a description of the structure, manufacture, and use of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention also resides in the claims hereinafter appended.