Electrode assembly including plated emitters

Abstract

To provide an electrode assembly that facilitates the treatment of tissue in anatomical locations not readily accessible.SOLUTION: An electrode assembly includes an elongate body 22, a proximal emitter 40, and a distal emitter 38. A discharge port 44 may be in fluid communication with a lumen 34 of the elongate body. The proximal and distal emitters are formed by plating a metal on an outer surface of the elongate body that is polymeric. A portion of the elongate body forms an insulative spacer 42 between the proximal emitter 40 and the distal emitter 38. A distal cap 46 may be coupled to the elongate body, formed from a conductive material, and arranged in electrical communication with the distal emitter. A distal lead, a thermocouple 62, and / or a hypotube 90 may be disposed within the lumen to form an electrical pathway with the distal cap. A sheath 104 may be disposed over a portion of the proximal emitter, and a radiopaque marker 106 may be coupled to the proximal emitter.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] [Claim of priority] This application claims priority to and the entire benefit of U.S. Provisional Patent Application No. 62 / 993,317, filed March 23, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Ablation systems are often used to selectively destroy neural tissue so that it no longer transmits pain signals to the brain. For example, an electrode assembly of an ablation system directs energy at the tissue to heat and destroy cells in the tissue. Other examples include ablating tumors in the liver, kidney, lung, and bone. Some ablation systems utilize fluids to improve the delivery of energy across the interface between the electrode assembly and the tissue. Summary of the Invention [Problem to be solved by the invention]

[0003] When the pathology is intraosseous, such as a bone tumor, the introducer assembly can facilitate positioning the electrode assembly at a target location within the bone. In some cases, it may be desirable for the introducer assembly to provide curvature to access bone tumors in difficult anatomical locations. One example includes tumors located posteriorly within the vertebral bodies of the spine. Many known electrode assemblies, particularly those with perfusion capabilities that require one or more internal lumens, cannot bend sufficiently to follow the curvature of the introducer assembly without degrading their functionality. Furthermore, the structure of many known electrode assemblies is complex, thus increasing manufacturing and assembly costs and the potential risk of component failure. Therefore, there is a need in the art for an electrode assembly for an ablation system that overcomes one or more of the above-mentioned drawbacks. [Means for solving the problem]

[0004] The electrode assembly of the present disclosure facilitates treatment of tissue in anatomical locations not easily accessible by conventional devices. More specifically, the flexibility of the elongate body of the electrode assembly can provide access to anatomical locations requiring a greater degree of curvature and / or a sharper radius of curvature, and can also provide infusion fluids to the anatomical locations. The electrode assembly includes an elongate body, a distal emitter, and a proximal emitter, the proximal emitter being electrically insulated from the distal emitter such that the electrode assembly is bipolar in structure. The elongate body is of one-piece construction and can be formed from a flexible material. The elongate body can include continuous portions proximal to the proximal emitter, between the distal emitter and the proximal emitter, and distal to the distal emitter. The elongate body includes an outer surface and can further include at least one inner surface defining at least one lumen. In some embodiments, the elongate body is polymeric, or at least partially formed from a polymer. The elongate body can be a tube extruded from polyether ether ketone (PEEK). The first lumen is configured to direct infusion fluid from a fluid source to an ejection port. The ejection port can be defined by or disposed on the proximal emitter, or by a portion of the elongate body forming an insulating spacer. The lumen can be optional, and the elongate body can be solid in cross section. The first lumen can be in fluid communication with the ejection port. The first lumen extends longitudinally beyond the ejection port near the distal end of the elongate body. The distal end of the elongate body can be closed-ended or fitted with a distal cap.

[0005] The distal emitter and the proximal emitter are coupled to or disposed on the elongate body. The distal emitter and the proximal emitter can be formed by plating a conductive material on the outer surface of the polymeric elongate body. The distal emitter can be formed by plating a metal on a first portion of the outer surface, and the proximal emitter can be formed by plating a metal or another metal on a second portion of the outer surface. The first and second portions are axially spaced from each other, such that a portion of the elongate body can form an insulating spacer between the proximal and distal emitters. The distal emitter and the proximal emitter are in electrical communication with a conductor for detachably coupling to an energy source. The electrode assembly includes a first electrical path in communication with the distal emitter. A thermocouple can be positioned to measure a temperature near the distal end of the electrode assembly. The elongate body can define a second lumen fluidly isolated from the first lumen, and the first electrical pathway and / or thermocouple is disposed within the second lumen. The first electrical pathway can be a distal lead or metal plated on an inner surface defining the second lumen. The thermocouple can be secured to the elongate body at or near the distal end.

[0006] The distal cap can be coupled to the elongate body and secured to the elongate body to seal the lumen. The distal cap can be formed from a conductive material and can be disposed in electrical communication with the distal emitter. The distal cap can form a portion of a first electrical pathway to transmit radio frequency (RF) energy to the distal emitter. The distal cap can be formed from a soldered metal to be electrically conductive, or a conductive adhesive can be applied to the interface between the distal cap and the elongate body, which are formed from metal.

[0007] The distal emitter can be disposed at the distal end of the elongate body. A first portion of the distal emitter can be plated on the outer surface of the elongate body, and a second portion of the distal emitter can be plated on the surface forming the distal end of the elongate body. The second portion is in electrical communication with the first portion. A proximal surface of a distal cap is secured to be in electrical communication with the second portion of the distal emitter. The distal cap can be secured not only to occlude the first and second lumens but also to secure the thermocouple leads in place. The distal cap can be formed from an electrically conductive material and can be formed from a material with sufficient thermal conductivity to effectively transfer heat detected by the thermocouple leads. The thermocouple is further configured to transfer radio frequency energy to the distal emitter through the distal cap. A third portion of the distal emitter can be plated on a portion of the inner surface near the distal end of the elongate body. The third portion communicates with the second portion and the first portion. The distal cap can be at least partially disposed or embedded within the first lumen to communicate with the third portion. The entire distal cap can be disposed within the first lumen, such that a distal surface of the distal cap is substantially coterminous with the distal end of the elongate body. A side surface of the distal cap is secured to the third portion of the distal emitter. The distal cap can include a proximal cap portion disposed within the lumen. The proximal cap portion can be in communication with the hypotube and the distal emitter and form part of the first electrical pathway. An arrangement in which a portion of the distal cap is disposed within the lumen includes a side surface secured to the third portion of the distal emitter.

[0008] The thermocouple leads can be disposed within the hypotube. The hypotube can be coaxially disposed within the first lumen. An annular gap between the hypotube and the inner surface of the elongate body can be in fluid communication with the ejection port. The thermocouple leads can be fluidly separable from the infusion fluid. The hypotube can include a distal end secured to the distal cap. The distal end of the hypotube can be closed and sized and shaped complementarily to a portion of the proximal surface of the distal cap. The hypotube can be formed from an electrically conductive material. The hypotube can be further configured to communicate with a conductor and transmit radio frequency energy through the distal cap to the distal emitter. A jacket can be formed from a non-conductive material and disposed between the distal end of the hypotube and the distal cap. The jacket can be configured to electrically insulate the hypotube from the distal cap without limiting thermal conductivity.

[0009] The electrode assembly further includes a second electrical pathway in electrical communication with the proximal emitter. The second electrical pathway is configured to transmit radio frequency energy to the proximal emitter. The second electrical pathway can be formed by metal plating, a lead, or the like on the inner surface defining the first lumen. The electrode assembly can include a sheath formed from a non-conductive material. The second electrical pathway can extend between the elongate body and the sheath. The sheath can be heat-shrink tubing, and the second electrical pathway can be defined by a plated conductor or proximal lead extending from the proximal emitter. The second electrical pathway and sheath can extend proximally for the entire length of the elongate body or a portion of the length.

[0010] The electrode assembly can include at least one radiopaque marker having sufficient radiodensity to be visible by x-ray imaging. The radiopaque marker can be attached to any suitable location along the elongate body. The radiopaque marker can be a band attached to the proximal emitter. The radiopaque marker can be positioned distal to the sheath to visually distinguish the proximal emitter by x-ray imaging. The radiopaque marker can form part of the second electrical pathway. The radiopaque marker is attached to the proximal emitter or a band securing the proximal lead to the proximal emitter. The distal cap is formed from a conductive material and is easily visible by x-ray imaging to visually distinguish the distal emitter by x-ray imaging.

[0011] According to some aspects of the present disclosure, an improved method for fabricating an electrode assembly is provided. The elongate body can be formed to define at least one lumen. The elongate body can be extruded to form a segment of polymer tubing, such as PEEK. An ejection port can be removed from the elongate body, the ejection port being in fluid communication with the lumen. The proximal and distal emitters can be plated onto the polymer tubing. A first layer of copper or nickel can be attached to the polymer tubing, and a second layer of gold or platinum can be plated onto the first layer. The proximal and distal emitters are spaced apart by a portion of the polymer tubing that forms an insulating spacer. The distal emitter is further plated onto the distal end of the elongate body, and a distal cap is secured to the distal end of the elongate body to communicate with the distal emitter. The distal emitter can be further plated on an inner surface of the elongate body defining the lumen, and the distal cap includes a proximal portion disposed within the lumen and secured to the inner surface. The distal cap is electrically conductive and solderable.

[0012] The method can include coupling a thermocouple to a distal cap. The thermocouple can be inserted into a hypotube, and the distal end of the hypotube can be crimped onto the thermocouple lead to form a thermocouple assembly. The thermocouple assembly can be directed through the lumen and secured to the distal cap. A jacket or adhesive can be disposed between the thermocouple and the hypotube, the jacket or adhesive being electrically insulating but thermally conductive. The hypotube can be disposed in electrical communication with the conductor. Alternatively, the distal lead can be secured to the distal cap. The distal cap can be formed by soldering a relatively small area of material to the distal lead, and the distal cap itself can then be capped with a non-conductive adhesive.

[0013] The method may further include placing a proximal lead in electrical communication with the proximal emitter. The proximal lead may be formed from metal plating on the elongate body or a discrete proximal conductor, such as a wire. A sheath may be disposed over the electrical pathway and, optionally, over a portion of the proximal emitter. The sheath may be tubing that is heat-shrunk over a portion of the proximal emitter. A radiopaque marker may be coupled to the proximal emitter. The radiopaque marker may be positioned adjacent to the sheath. The radiopaque marker may be a band crimped or swaged on the proximal lead. The distal cap is formed from a conductive material, and the radiopaque marker provides a visual indicator by x-ray imaging that distinguishes the distal and proximal emitters, respectively. The electrode assembly may be disposed in a kit with an access cannula and an introducer device. The result is a lower cost, potentially disposable electrode assembly that provides improved flexibility for injection to access anatomical locations with a greater degree of curvature and / or a sharper radius of curvature.

[0014] Advantages of the present invention will be readily appreciated as they become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which: It should be appreciated that the drawings are illustrative in nature and are not necessarily drawn to scale. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of an ablation system including an electrode assembly. [Figure 2] FIG. 2 is a detailed view of the electrode assembly of FIG. [Figure 3] FIG. 2 is an elevational view of a portion of the electrode assembly of FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view of a portion of the electrode assembly of FIG. 3. [Figure 5] 5 is an axial view of a portion of the electrode assembly of FIG. 3 taken along line 5-5. [Figure 6] FIG. 10 is a cross-sectional view of a portion of another embodiment of an electrode assembly. [Figure 7] FIG. 10 is a cross-sectional view of a portion of another embodiment of an electrode assembly. [Figure 8] FIG. 10 is a cross-sectional view of a portion of another embodiment of an electrode assembly. [Figure 9] FIG. 10 is a cross-sectional view of a portion of another embodiment of an electrode assembly. [Figure 10] FIG. 10 is a cross-sectional view of a portion of another embodiment of an electrode assembly. [Figure 11] FIG. 1 is a schematic representation of a vertebra in which an electrode assembly is deployed with an introducer assembly to ablate an intraosseous tumor or basal spinal nerve. DETAILED DESCRIPTION OF THE INVENTION

[0016] Referring to FIG. 1 , an ablation system includes an electrode assembly 12 configured to treat tissue. The electrode assembly 12 includes an elongated body 22 having a defined length between a proximal end 16 and an opposite distal end 20. Near the distal end 20 of the elongated body 22, the electrode assembly 12 includes a distal emitter 38 and a proximal emitter 40 positioned proximally relative to the distal emitter 38. The distal emitter 38 and the proximal emitter 40 can be electrically isolated from each other such that the electrode assembly is bipolar in structure. Embodiments of the present disclosure can be provided for monopolar electrode assemblies that require a grounding source, such as a ground pad.

[0017] The electrode assembly 12 includes at least one conductor 50 in communication with the distal emitter 38 and the proximal emitter 40, and a connector 52 in communication with the conductor 50. The connector 52 is configured to be detachably coupled to an energy source 54, for example, an electrosurgical generator. One suitable energy source 54 is the radio frequency generator and control console sold by Stryker Corporation (Kalamazoo, Mich.) under the trade names MultiGen (MG1) and MultiGen2 (MG2), which are described in commonly owned International Publication No. WO 2018 / 0200254, published November 1, 2018, the entire contents of which are incorporated herein by reference. The energy source 54 may be capable of supplying a variable current to the electrode assembly 12. The control console may allow adjustment of the frequency, current, and / or voltage levels of the supplied current over various time periods. Energy from the energy source 54 is delivered to the distal emitter 38 and the proximal emitter 40 such that the distal emitter 38 and the proximal emitter 40 have opposite polarities. When positioned in or adjacent to tissue, the energy passing between the distal emitter 38 and the proximal emitter 40 heats and cauterizes the tissue, or alternatively, facilitates electrosurgical cutting or coagulation.

[0018] As previously mentioned, conventional electrode assemblies, particularly those with fluid injection, irrigation, or internal cooling, generally cannot achieve more than a minimal curvature. These electrode assemblies cannot achieve sufficient posterior access within the vertebral body through a unilateral pedicle approach, among other procedures requiring off-axis positioning. The electrode assembly 12 of the present disclosure advantageously provides a highly flexible elongate body 22. Furthermore, the elongate body 22 can extend near or to the distal end 20 of the electrode assembly 12 so that substantially the entire length of the elongate body 22 is flexible. In other words, the elongate body 22 is a unitary structure of flexible material and extends at least distal to the proximal emitter 40, and in some cases, distal to the distal emitter 38. For example, FIG. 3 illustrates an elongate body 22 having continuous portions proximal to the proximal emitter 40, between the distal emitter 38, and distal to the distal emitter 38. In alternative embodiments, it is envisioned that elongate body 22 is formed from two or more subcomponents. Due to its flexibility, elongate body 22 is configured to bend or curve when deployed through introducer assembly 13 (see FIG. 11), as further described.

[0019] The elongate body 22 can define the distal end 20 of the electrode assembly 12, and the elongate body 22 can define the proximal end 16. In some embodiments, the electrode assembly 12 includes a hub 23 (see FIG. 11 ), and the elongate body 22 extends distally from the hub 23. Referring now to FIGS. 3 and 4 , the elongate body 22 includes an outer surface 72 and can further include at least one inner surface 70 that defines at least one lumen 34, 35 as described. In some embodiments, the elongate body 22 comprises a polymer, i.e., is at least partially formed from a polymer. The elongate body 22 may be extruded, molded, or shaped through other suitable manufacturing techniques, and can be formed from films, fibers, fabrics, and powders. In one example, the elongate body 22 is a tube extruded from polyetheretherketone (PEEK), which is highly flexible and has material properties suitable for medical devices. Additionally, in embodiments having two or more lumens 34, 35, extruding PEEK tubing can reduce manufacturing complexity and cost over known devices. Other suitable materials are contemplated, such as polytetrafluoroethylene (Teflon™), phenolic, polycarbonate, polysulfone, and polyoxymethylene, among others. Suitable materials can have a Young's modulus of less than 3.6 gigapascals (GPa).

[0020] The distal emitter 38 and the proximal emitter 40 are coupled to or disposed on the elongate body 22. More specifically, the distal emitter 38 and the proximal emitter 40 can be formed by plating a conductive material onto the outer surface 72 of the polymeric elongate body 22. An exemplary plating process involves electroplating a metal onto the polymeric elongate body 22, which is shown schematically by stippling in FIGS. 1-3. One suitable manufacturing process for plating a metal onto a polymer was developed by SAT Plating (Troy, Mich.). In one example, the metal is gold, but other suitable materials include copper, nickel, stainless steel, titanium, and chromium, among others. For example, a first layer of copper or nickel can be applied to the polymer tube, and a second layer of gold or platinum can be plated onto the first layer. Plating a metal onto the polymeric material makes the distal emitter 38 and the proximal emitter 40 electrically conductive to transmit radio frequency energy without adversely affecting the flexibility of the elongate body 22. Other suitable methods by which the proximal and distal emitters may be plated include electroless plating, electrodeposition, immersion, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma spraying, and the like.

[0021] As previously mentioned, the distal emitter 38 is spaced and electrically isolated from the proximal emitter 40, which is necessary for the electrode assembly 12 to be operable as a bipolar electrode. The distal emitter 38 can be formed by plating a metal onto a first portion 56 of the outer surface 72, and the proximal emitter 40 can be formed by plating a metal or another metal onto a second portion 58 of the outer surface 72. The first portion 56 and the second portion 58 can be axially spaced from one another, such that a portion of the elongate body 22 forms an insulating spacer 42 between the distal emitter 38 and the proximal emitter 40. For example, in embodiments in which the elongate body 22 is a PEEK tube, the PEEK tube itself is non-conductive and therefore forms the insulating spacer 42 between the distal emitter 38 and the proximal emitter 40. The distal emitter 38 and the proximal emitter 40 are thus electrically isolated without the need for discrete insulating spacers, which may require mechanical bonding with adhesives, threads, lap joints, etc. In addition to the increased flexibility and reduced manufacturing complexity and cost discussed above, the arrangement eliminates interfaces between discrete components and the potential for escaping infusion fluid through the interfaces, particularly with bending of the electrode assembly 12 at larger bend angles and sharper curvatures. Fluid escaping at the interfaces could otherwise result in virtual electrodes during operation "within" the device, which could degrade device functionality. The electrode assembly 12 of the present disclosure overcomes this shortcoming.

[0022] The first lumen 34 can be configured to direct infusion fluid from a fluid source (not shown) to the ejection port 44. The ejection port 44 can be positioned at any suitable location along the length of the elongate body 22, and more than one ejection port 44 can be provided. FIGS. 2-4 illustrate an ejection port 44 defined by or disposed on the proximal emitter 40, while FIGS. 5-10 illustrate an ejection portion defined by a portion of the elongate body 22 forming the insulating spacer 42, i.e., between the distal emitter 38 and the proximal emitter 40. Positioning the ejection port 44 proximal to the distal emitter 38 advantageously allows the infusion fluid to descend along the surface of the distal emitter 38 under the influence of gravity when the electrode assembly 12 is deployed within the anatomy at an approach angle. For example, microinfusion of a fluid (e.g., saline or another conductive fluid) via a microinfusion module (not shown) facilitates energy transfer across the tissue-emitter interface, which helps control temperature, impedance, hydration, and ion concentration to prevent carbonization of biological tissue. One suitable microinfusion module is disclosed in commonly owned International Publication No. WO 2020 / 0198150, published November 5, 2020, the entire contents of which are incorporated herein by reference. The microinfusion module can be releasably coupled to the electrode assembly 12, for example, by a Luer lock fitting coupled to the fluid coupling 36 (see FIG. 1 ). The microinfusion module can be considered “micro” due to its relatively small form factor and / or the amount of fluid infused at a relatively low rate. However, it should be appreciated that the lumens 34, 35 are optional and the cross-section of the elongate body 22 can be solid. The resulting electrode assembly is not capable of providing injection, and electronic subcomponents can be positioned along the outer surface 72 of the elongate body 22. One or more sheaths can be provided to electrically insulate some components as needed.

[0023] The first lumen 34 is in fluid communication with the ejection port 44 and can otherwise be disposed in any suitable manner within the elongate body 22. For example, FIG. 4 illustrates the first lumen 34 extending longitudinally within a portion of the elongate body 22 and then turning radially outward relative to the ejection port 44. FIGS. 6-10 illustrate the first lumen 34 extending longitudinally beyond the ejection port to near the distal end 20 of the elongate body 22. In embodiments in which the first lumen 34 extends distally of the ejection port 44, the distal end 20 of the elongate body 22 can be formed as a closed end ( FIG. 4 ) or filled with a distal cap 46 ( FIGS. 6-10 ), which will be described in detail. For example, the distal end 20 of the elongate body 22 illustrated in FIG. 4 can be formed by a catheter tip fabrication process in which heat is applied to at least partially round, tape, or close the distal end 20 of the elongate body 22. Alternatively, the distal end 20 can define an ejection port or another ejection port. Figures 6-10 show the lumens 34, 35 extending to the distal end 84 of the elongate body 22, with the distal cap 46 coupled to the distal end 84 of the elongate body 22. This arrangement results in the lumens 34, 35 extending the entire length of the elongate body 22 while maintaining a constant axial cross-section of the elongate body 22, which can provide a form factor particularly suitable for extruded elongate bodies 22, and as such, is a less complex and more cost-effective manufacturing process for fabricating smaller gauge devices, such as 22 gauge, 14 gauge, etc., as in some embodiments herein. Similarly, fabrication of multi-lumen tubing can be achieved by extrusion in a more efficient manner. Other suitable manufacturing techniques include vacuum forming, injection molding, blow molding, additive manufacturing, braiding, etc.

[0024] The distal emitter 38 and the proximal emitter 40 are in electrical communication with the conductor 50 so as to be detachably coupled to the energy source 54. To facilitate electrical connection, the electrode assembly 12 includes a first electrical pathway 76 in electrical communication with the distal emitter 38. Additionally, the electrode assembly 12 may include a thermocouple 62 positioned to measure the temperature near the distal end 20 of the electrode assembly 12, the thermocouple 62 being shown schematically in FIG. 4 and as a pair of leads 80, 82 in FIGS. 6-10. The control console may be configured to adjust the delivered radiofrequency energy based on the temperature measured by the thermocouple 62, along with other measured parameters. The elongate body 22 may define a second lumen 35 fluidly isolated from the first lumen 34, with the first electrical pathway 76 and / or the thermocouple 62 disposed within the second lumen 35. Continuing with reference to FIG. 4 , the first electrical pathway 76 can extend through the second lumen 35 to communicate with the distal emitter 38. For example, the first electrical pathway 76 can be a distal lead 92 or metal plated on the inner surface 70 defining the second lumen 35. A small hole (not shown) can extend from the inner surface 70 to the outer surface 72 to provide electrical communication between the first electrical pathway 76 within the second lumen 35 and the distal emitter 38 on the outer surface 72. The thermocouple 62 can be secured to the elongate body 22 at or near the distal end 20 by any suitable coupling means. In some embodiments, one or more additional thermocouples (not shown) can be positioned proximal to the proximal emitter 40. The additional thermocouple can be configured to monitor the progress of an ablated lesion at a location proximal to the distal end 20 of the electrode assembly 12. The control console can be configured to adjust the delivered radio frequency energy based on the temperature measured by the additional thermocouple.

[0025] The multi-lumen arrangement prevents possible degradation of the electrical components from infusion fluids. Additionally, because the elongate body 22 itself provides a barrier separating the first lumen 34 from the second lumen 35, there is little sacrifice in flexibility of the elongate body 22 and there are fewer concerns about degradation of the internal components or interfaces between internal components.

[0026] 6-10 , the distal cap 46 can be coupled to the elongate body 22. The distal cap 46 can define the distal end 20 of the electrode assembly 12. The distal cap 46 can be secured to the elongate body 22 to seal the lumens 34, 35. Additionally, the distal cap 46 can be formed from an electrically conductive material and can be disposed in electrical communication with the distal emitter 38. As will be further described, the distal cap 46 can form a portion of the first electrical pathway 76 for transmitting radio frequency energy to the distal emitter 38. The distal cap 46 can be disposed in electrical communication with the distal emitter 38, which is positioned on the outer surface 72 of the elongate body 22, with the distal lead 92 (and / or thermocouple 62) disposed within the lumens 34, 35. In such an arrangement, the electrical subcomponents of the electrode assembly 12 can be internal to the elongate body 22 while still transmitting the necessary radio frequency energy to the distal emitter 38 on the exterior of the elongate body 22. In one example, the distal cap 46 itself is formed from soldered metal and is therefore electrically conductive; in another example, a conductive adhesive can be applied to the interface between the metal-formed distal cap 46 and the elongate body 22. In some embodiments, the distal cap 46 can be formed from a material that is both thermally and electrically non-conductive. For example, the distal cap 46 can be formed with a relatively small area of solder for the distal lead 92, and then the distal cap 46 itself is capped with a non-conductive adhesive.

[0027] 6 illustrates an embodiment of the electrode assembly 12 in which a portion of the distal emitter 38 is disposed on the distal end 84 of the elongate body 22. More specifically, a first portion 86 of the distal emitter 38 is plated on the outer surface 72 of the elongate body 22, and a second portion 88 of the distal emitter 38 is plated on the surface forming the distal end 84 of the elongate body 22. The second portion 88 is in electrical communication with the first portion 86 and can be considered to be a lip extending radially inward around the distal end 84 of the elongate body 22. The proximal surface 48 of the distal cap 46 is secured in electrical communication with the second portion 88 of the distal emitter 38. The soldered metal itself, upon solidification, may comprise the proximal surface 48, or alternatively, the distal cap 46 may be a discrete metal component including the proximal surface 48.

[0028] The embodiment of FIG. 6 further illustrates the elongate body 22 defining the first lumen 34 and the second lumen 35 fluidly isolated from the first lumen 34. The leads 80, 82 of the thermocouple 62 extend through the second lumen 35 and are secured to the distal cap 46. The distal cap 46 can be soldered not only to occlude the first and second lumens 34, 35, but also to secure the leads 80, 82 of the thermocouple 62 in place. Alternatively, the leads 80, 82 can be secured to the distal cap 46 by adhesive, crimping, a friction fit, or the like. The distal cap 46 can be formed from an electrically conductive material and can also be formed from a material with sufficient thermal conductivity. The distal cap 46 effectively transfers heat, for example, from adjacent tissue undergoing ablation, which is then sensed by the leads 80, 82 of the thermocouple 62, which are themselves electrically conductive. An electrical signal indicative of the temperature is transmitted from the thermocouple 62 to the control console. It is further contemplated that, due to the leads 80, 82 of the thermocouple 62 being electrically conductive, in some embodiments the thermocouple 62 may be further configurable to transmit radio frequency energy to the distal emitter 38 through the distal cap 46. In such an arrangement, the first electrical pathway 76 may not require a distal lead 92 to transmit radio frequency energy from the conductor 50 to the distal emitter 38 (see FIGS. 3 and 8).

[0029] Referring now to FIG. 7, another embodiment of the electrode assembly 12 is shown in which a hypotube 90 is provided and the leads 80, 82 are disposed within the hypotube 90. While FIG. 6 illustrates the elongate body 22 defining the first lumen 34 and the second lumen 35, FIG. 7 illustrates a single lumen (first lumen 34) with the hypotube 90 coaxially disposed within the first lumen 34. In such an arrangement, the first lumen 34, and particularly the annular gap between the hypotube 90 and the inner surface 70 of the elongate body 22, are in fluid communication with the discharge port 44. The leads 80, 82 of the thermocouple 62 are fluidly isolated from the infusion fluid.

[0030] The hypotube 90 can include a distal end 94 that is secured to the distal cap 46 by, for example, solder, adhesive, or the like. Furthermore, a first portion 86 of the distal emitter 38 is plated on the outer surface 72 of the elongate body 22, and a second portion 88 of the distal emitter 38 is plated on the surface forming the distal end 84 of the elongate body 22, with the first portion 86 and the second portion 88 in electrical communication with the distal cap 46. The distal end 94 of the hypotube 90 can be closed-ended as shown, and in one example, a portion of the proximal surface 48 of the distal cap 46 is hemispherical, to which the distal end 94 of the hypotube 90 is hemispherical in size and shape, complementary to the hemispherical shape. The hypotube 90 can be formed from an electrically conductive material, for example, stainless steel. It is contemplated that in some embodiments, the hypotube 90 can be further configured to communicate with the conductor 50 to transmit radio frequency energy through the distal cap 46 to the distal emitter 38. In such an arrangement, the first electrical pathway 76 may not require a distal lead 92 for transmitting radio frequency energy to the distal emitter 38 (see FIGS. 3 and 8 ). It should also be appreciated that the hypotube 90 can be formed with sufficient flexibility so as not to limit the flexibility of the elongate body 22. When the hypotube 90 is formed from a conductive material, a jacket 96 formed from a non-conductive material can be disposed between the distal end 94 of the hypotube 90 and the thermocouple 62. The jacket 96 can be configured to electrically insulate the hypotube 90 from the thermocouple 62 without limiting thermal conductivity therebetween. Examples of suitable materials for the jacket 96 include a thermal adhesive or a heat shrink.

[0031] 8 shows one embodiment of the electrode assembly 12 in which a first portion 86 of the distal emitter 38 is plated on the outer surface 72 of the elongate body 22, a second portion 88 of the distal emitter 38 is plated on the surface forming the distal end 84 of the elongate body 22, and a third portion 98 is plated on a portion of the inner surface 70 near the distal end 84 of the elongate body 22. The third portion 98 is in electrical communication with the second portion 88 and the first portion 86, and the distal emitter 38 can be considered to be generally cylindrical in shape. The illustrated embodiment shows the first portion 86 extending proximally from the distal end 84 of the elongate body 22 a greater distance than the third portion 98, although alternative relative dimensions are contemplated.

[0032] Once the third portion 98 is disposed within the first lumen 34, the distal cap 46 is at least partially disposed or embedded within the first lumen 34 and is in electrical communication with the third portion 98 (see also FIGS. 9 and 10 ). FIG. 8 shows the entire distal cap 46 disposed within the first lumen 34 such that the distal surface of the distal cap 46 is generally coterminous with the distal end 84 of the elongate body 22. A side surface 100 of the distal cap 46 is secured to the third portion 98 of the distal emitter 38. The soldered metal itself may include the side surface 100 upon solidification, or alternatively, the distal cap 46 may be a discrete metal component including the side surface 100.

[0033] The embodiment of Figure 8 further illustrates the elongate body 22 defining the first lumen 34, with the leads 80, 82 of the thermocouple 62 and the distal lead 92 of the electrical pathway 76 disposed within the first lumen 34. It should be appreciated that the leads 80, 82, 92 may be disposed within a jacket or sheath (not shown) to electrically insulate the electrical components from the infusion fluid. It should further be appreciated that the distal cap 46 of this embodiment may be used in combination with a hypotube 90, an elongate body 22 having a first lumen 34 and a second lumen 35, and / or any other compatible embodiment of the present disclosure.

[0034] FIG. 8 illustrates the distal cap 46 disposed within the lumen 34, and FIGS. 9 and 10 illustrate the distal cap 46 that is dome-shaped and further includes a proximal cap portion 102 disposed within the lumen 34. In one embodiment, the distal cap 46 is more easily solderable within the lumen 34 as opposed to reproducibly soldering a domed end. The proximal cap portion 102 is in electrical communication with the hypotube 90 and the distal emitter 38 and can form a portion of the first electrical pathway 76. An arrangement in which a portion of the distal cap 46 is disposed within the lumen 34 includes a side surface 100 that is secured to the third portion 98 of the distal emitter 38. Among other advantages, the interface between the side surface 100 and the third portion 98 experiences shear forces as opposed to tensile forces, providing a more robust design for accommodating fluids under pressure. The infusion fluid may be at a pressure of approximately 1 bar, although the distal cap 46 may be configured to accommodate greater pressures.

[0035] The first electrical pathway 76 is configured to transmit radio frequency energy to the distal emitter 38. The electrode assembly 12 further includes a second electrical pathway 78 in electrical communication with the proximal emitter 40 and configured to transmit radio frequency energy to the proximal emitter 40. Referring again to FIG. 4 , the second electrical pathway 78 is coupled to the proximal emitter 40 across the bend defined by the first lumen 34. The second electrical pathway 78 can be formed by metal plating, leads, or the like on the inner surface 70 defining the first lumen 34. Positioning the first electrical pathway 76 within the elongate body 22 can be desirable because the first electrical pathway 76 should be insulated from the second electrical pathway 78, but nevertheless extends axially beyond the proximal emitter 40. In other words, for example, having the first electrical pathway 76 within the lumens 34, 35, as opposed to the distal lead 92 extending along the outer surface 72 of the elongate body 22 beyond the proximal emitter 40, can reduce concerns about arcing or electrical degradation. Such concerns are less pronounced with respect to the proximal emitter 40 because the lead extending proximally from the proximal emitter 40 is not electrically connected to the distal emitter 38. However, because the proximal emitter 40 may be C-shaped to define a gap (not shown), it is envisioned that the distal lead 92 will extend through the gap so as to be electrically isolated from the proximal emitter 40.

[0036] 7-10, the electrode assembly 12 can include a sheath 104 formed from a non-conductive material. A second electrical pathway 78 can extend between the elongate body 22 and the sheath 104. In some embodiments, the sheath 104 is heat-shrink tubing, and the second electrical pathway 78 is defined by a plated conductor, or proximal lead 108, extending from the proximal emitter 40. FIGS. 7-9 show the plated conductor, which can be considered part of the proximal emitter 40, disposed beneath the sheath 104. The plated conductor beneath the sheath 104 can extend around the outer diameter of the elongate body 22, like the proximal emitter 40, or can be narrow, similar to a plated lead. FIG. 10 shows the proximal lead 108 coupled to the outer surface of the proximal emitter 40 and disposed between the sheath 104 and the elongate body 22. The second electrical pathway 78 and sheath 104 can extend proximally for the entire length of the elongate body 22, or for a portion thereof. In one example, the second electrical pathway 78 and sheath 104 can extend proximally until they are disposed below the hub 23 coupled over the proximal portion of the elongate body 22 (see FIG. 11 ).

[0037] Because the elongate body 22 is a polymer, it can be relatively radiopaque for fluoroscopy and other x-ray imaging. The electrode assembly 12 of the present disclosure can include at least one radiopaque marker 106 that has sufficient radiodensity to be visible by x-ray imaging. The radiopaque marker 106 can be coupled to any suitable location along the elongate body 22. In an exemplary embodiment, and with reference to FIGS. 9 and 10 , the radiopaque marker 106 is a band coupled to the proximal emitter 40. Additionally, the radiopaque marker 106 can be positioned just distal to the sheath 104 to visually distinguish the proximal emitter 40 by x-ray imaging. The radiopaque marker 106 can be formed from a metal such as platinum or platinum iridium so that it is easily visualized by x-ray imaging. The radiopaque marker 106 can form a portion of the second electrical pathway 78. For example, Figure 9 shows a radiopaque marker 106 coupled to the proximal emitter 40, and Figure 10 shows the radiopaque marker 106 as a band that secures the proximal lead 108 to the proximal emitter 40. The radiopaque marker 106 can be crimped, swaged, or otherwise secured to the proximal emitter 40 or elongate body 22.

[0038] As explained above, the distal cap 46 is formed from a conductive material. Therefore, the distal cap 46 is easily visualized by x-ray imaging, allowing for visual identification of the distal emitter 38 by x-ray imaging. When the elongate body 22 is relatively radiolucent, the distal cap 46 and the radiopaque marker 106 are particularly noticeable by x-ray imaging, facilitating precise positioning within the anatomical location of interest. It is therefore readily apparent that the distal cap 46 serves several functions related to the electrode assembly 12. In some embodiments, a separate radiopaque marker (not shown) may be a band that is crimped near the distal end 20 of the electrode assembly 12. Such an arrangement may be particularly suitable in cases where the distal cap 46 is adhesive or formed from another material that is not sufficiently radiopaque. Additionally or alternatively, the distal emitter 38 and the proximal emitter 40 formed by metal plating may themselves be radiopaque. For example, plating with a sufficiently thick layer of a metal having a high atomic weight, such as gold or platinum, can provide sufficient radiodensity to be visualized by x-ray imaging. It is further contemplated that the radiopaque marker 106 need not be disposed on or coupled to the outer surface 72 of the elongate body 22. In some embodiments, the radiopaque marker 106 can be disposed within the lumens 34, 35. For example, a segment of wire, such as a tungsten wire, can be secured at one or more desired locations within the lumens 34, 35.

[0039] The electrode assembly 12 of the present disclosure facilitates tissue treatment in anatomical locations previously inaccessible using conventional devices. More particularly, the flexibility of the elongate body 22 can provide access to anatomical locations requiring a greater degree of curvature and / or a sharper radius of curvature. Referring now to FIG. 11 , the elongate body 22 is configured to bend or curve when deployed through the introducer assembly 13. One suitable introducer assembly is disclosed in commonly owned U.S. Patent No. 9,839,443, issued December 12, 2017, the entire contents of which are incorporated herein by reference. In some embodiments, the elongate body 22 is sufficiently flexible to be deployed through a curve of at least 60 degrees, more particularly at least 90 degrees, and even more particularly at least 120 degrees. Furthermore, the elongate body 22 is sufficiently flexible to be deployed through a curve having a radius of curvature within the range of approximately 0.75 to 2.50 inches, more particularly within the range of approximately 1.25 to 2.25 inches.

[0040] The ablation system 11 can include an electrode assembly 12, an introducer assembly 13, and an access cannula 14. The ablation system 11 can be packaged as a kit. An exemplary method in which the ablation system 11 can be deployed is for ablation of a bone tumor (BT) within a vertebral body. The bone tumor is shown as being significantly posterior and significantly contralateral to the pedicle through which the access cannula 14 is deployed. The electrode assembly 12 is shown deployed through an approximately 180-degree bend to access the bone tumor. Another exemplary method in which the ablation system 11 can be deployed is for ablation of the basal spinal nerve (BVN) within a vertebral body. For optical results, it is known that the major posterior aspect of the basal spinal nerve should be ablated. To access the major posterior aspect of the basal spinal nerve, the electrode assembly 12 is shown deployed through an approximately 270-degree bend. Alternatively, the electrode assembly 12 can be deployed through a sharper bend to access the major posterior aspect of the basal spinal nerve.

[0041] The access cannula 14 is deployed through the pedicle, and the introducer assembly 13 is deployable through the access cannula 14. The introducer assembly 13 can include a sheath 15 configured to be positioned within the vertebral body in a curved configuration over the access cannula 14. The electrode assembly 12 is configured to follow the curved configuration of the sheath 15 or the curved path within the bone created by the introducer assembly 13. The distal end 20 of the electrode assembly 12 can be positioned approximately in alignment with the distal end of the sheath 15. Positioning by the electrode assembly 12 can be confirmed by x-ray imaging by visualizing the distal cap 46 and the radiopaque marker 106. The sheath 15 can be retracted to expose the distal emitter 38 and proximal emitter 40 of the electrode assembly 12, 12′, for example, within a bone tumor or over a basal spinal nerve. The electrode assembly 12, 12′ is activated to ablate the bone tumor or basal spinal nerve. It will be appreciated that the ablation system 11 of the present disclosure can be used in any suitable anatomical location, including bony or non-bone applications. Exemplary non-bone applications include facet rhizotomy, sacroiliac nerve blocks, genicular nerve blocks, and the like.

[0042] The above disclosure is not intended to be exhaustive or to limit the present invention to any particular form. The terminology used is intended to be in the nature of words of description rather than limitation. Many modifications and variations are possible in light of the above teachings, and the present invention may be practiced otherwise than as specifically described. For example, it should be appreciated that the inner diameter of the first lumen 34 (and / or second lumen 35) is not shown to scale in FIGS. 4-10 but rather may be exaggerated for a more meaningful illustration of the components of the electrode assembly 12. In other words, the thermocouple 62, hypotube 90, and / or distal lead 92 may be in a relatively conformal arrangement within the first lumen 34. An additional medium, e.g., a dielectric material, may be provided to occlude any free space within the first lumen 34.

Claims

1. An electrode assembly, an elongate body having an outer surface opposite an inner surface defining a lumen, the elongate body being formed from a non-conductive material; a proximal emitter formed by plating a metal onto a first portion of the outer surface; a distal emitter formed by plating the metal or another metal onto a second portion of the outer surface; Equipped with The electrode assembly, wherein the first portion and the second portion are spaced apart from one another such that the elongate body forms an insulating spacer between the proximal emitter and the distal emitter.

2. 10. The electrode assembly of claim 1, further comprising a distal cap coupled to the elongate body to define a distal end of the electrode assembly, the distal cap being formed from a conductive material and positioned in electrical communication with the distal emitter.

3. An electrode assembly, an elongate body having an outer surface opposite an inner surface defining a lumen, the elongate body being formed from a non-conductive material; a proximal emitter disposed on a first portion of the outer surface; a distal emitter disposed on a second portion of the outer surface, the first portion and the second portion spaced apart from one another such that the elongated body forms an insulating spacer between the proximal and distal emitters; and a distal cap coupled to the elongate body to define a distal end of the electrode assembly, the distal cap being formed from a conductive material and disposed in electrical communication with the distal emitter; An electrode assembly comprising:

4. 4. The electrode assembly of claim 2 or 3, wherein the distal cap is secured to a distal surface of the elongate body, and the distal emitter is further formed by electrodepositing the metal on the distal surface.

5. 5. The electrode assembly of claim 2, wherein the distal cap is at least partially secured within the lumen, and the distal emitter is further formed by electrodepositing the metal on the inner surface.

6. The electrode assembly of any one of claims 2 to 5, further comprising a distal lead extending through the lumen and in electrical communication with the distal cap.

7. The electrode assembly of any one of claims 2 to 6, further comprising a thermocouple extending through the lumen and in thermal communication with the distal cap.

8. 8. The electrode assembly of claim 7, further comprising a hypotube extending through the lumen and having a closed distal end coupled to the distal cap, the thermocouple disposed within the hypotube.

9. 9. The electrode assembly of claim 8, further comprising a jacket disposed on said thermocouple to electrically insulate said thermocouple from said hypotube.

10. 10. The electrode assembly of claim 8 or 9, wherein the elongate body further defines an injection port in fluid communication with the lumen.

11. The electrode assembly of any one of claims 1 to 10, further comprising a sheath coaxially disposed over a portion of the proximal emitter, the sheath being formed from a non-conductive material.

12. The electrode assembly of claim 11 , further comprising a proximal lead disposed in conductive communication with the proximal emitter and extending proximally between the sheath and the outer surface of the elongate body.

13. The electrode assembly of claim 12 , further comprising a radiopaque marker band securing the proximal lead to the proximal emitter.

14. An electrode assembly, an elongate body having an outer surface opposite an inner surface defining a lumen, the elongate body being formed from a non-conductive material; a proximal emitter disposed on a first portion of the outer surface; a distal emitter disposed on a second portion of the outer surface, the first portion and the second portion spaced apart from one another such that the elongated body forms an insulating spacer between the proximal and distal emitters; and a sheath coaxially disposed over a portion of the proximal emitter, the sheath being formed from a non-conductive material; An electrode assembly comprising:

15. The electrode assembly of any one of claims 1 to 14, further comprising a radiopaque marker coupled to the proximal emitter.

16. An electrode assembly, an elongate body having an outer surface opposite an inner surface defining a lumen, the elongate body being formed from a non-conductive material; a proximal emitter disposed on a first portion of the outer surface; a distal emitter disposed on a second portion of the outer surface, the first portion and the second portion spaced apart from one another such that the elongated body forms an insulating spacer between the proximal and distal emitters; and a sheath disposed over a portion of the proximal emitter, the sheath being formed from a non-conductive material; a proximal lead disposed in conductive communication with the proximal emitter and extending proximally between the sheath and the outer surface of the elongate body; a radiopaque marker band that secures the proximal lead to the proximal emitter; An electrode assembly comprising:

17. 17. The electrode assembly of claim 1, wherein the lumen is a first lumen, the inner surface of the elongate body defines a second lumen fluidly isolated from the first lumen, an injection port is in fluid communication with the second lumen, the first lumen defines an electrical pathway for an electrical component, and the second lumen defines a fluid pathway through which fluid received from a fluid source is expelled through the injection port.

18. 18. The electrode assembly of claim 17, wherein the injection port is axially positioned within the proximal emitter or the insulating spacer.

19. The electrode assembly of any one of claims 2 to 18, wherein the distal cap is solder.

20. An electrode assembly, an elongate body formed from a non-conductive material, the elongate body having an outer surface opposing an inner surface defining a first lumen, a second lumen fluidly separated from the first lumen, and an injection port in fluid communication with the second lumen; a proximal emitter disposed on a first portion of the outer surface; a distal emitter disposed on a second portion of the outer surface, the first portion and the second portion spaced apart from one another such that the elongated body forms an insulating spacer between the proximal and distal emitters; and Equipped with An electrode assembly, wherein the first lumen defines an electrical pathway for electrical components of the electrode assembly, and the second lumen defines a fluid pathway through which fluid received from a fluid source is expelled through the injection port.

21. 21. The electrode assembly of claim 3, 14, 16 or 20, wherein the proximal emitter and the distal emitter are formed by plating metal onto the outer surface of the elongate body.

22. 22. The electrode assembly of claim 21, wherein the metal is selected from the group consisting of gold, platinum, copper, nickel, stainless steel, titanium, and chromium.

23. 21. The electrode assembly of claim 3, 14, 16, or 20, wherein the proximal emitter and the distal emitter are formed from the group consisting of electroless plating, electrodeposition, immersion, physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma spraying.

24. An electrode assembly according to any preceding claim, wherein the elongate body is of unitary construction.

25. 25. The electrode assembly of claim 24, wherein the elongated body is an extruded segment of polyetheretherketone (PEEK).

26. An electrode assembly according to any one of claims 1 to 25; a micro-injection module; An ablation system comprising:

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