MICROWAVE ANTENNA PROBE HAVING A DEPLOYABLE GROUND PLANE

Abstract

A surgical ablation system employing an ablation probe having a deployable ground plane includes a source of ablation energy and a source of electrosurgical energy, and a switching assembly configured to select between ablation and electrosurgical modes. The probe includes a cannula having a shaft slidably disposed therein. The shaft includes a deployable ground plane electrode assembly and a needle electrode disposed at distal end of the shaft. As the shaft is extended distally from the cannula, the ground plane electrode unfolds, and the needle electrode is exposed. Electrosurgical energy is applied to tissue via the needle electrode to facilitate the insertion thereof into tissue. Ablation energy is applied to tissue via the needle electrode to achieve the desired surgical outcome. The shaft, ground plane electrode and needle electrode are retracted into the cannula, and withdrawn from the surgical site.

Claims

1. A surgical ablation system, comprising: a source of ablation energy; a source of electrosurgical energy; a switching assembly configured to selectively and operably couple at least one of the source of ablation energy or the source of electrosurgical energy to an inner conductor of an ablation probe, the ablation probe including: a cannula having a proximal end and a distal end; a shaft slidably disposed within the cannula and having at least a stowed position and a deployed position; an inner conductor adapted to operably couple to the switching assembly, the inner conductor coaxially disposed within the shaft and extending from a distal end thereof to form a needle electrode; and a deployable ground plane electrode assembly disposed about a distal end of the shaft, wherein when the shaft is in a stowed position, the deployable ground plane electrode is substantially contained within the cannula, and when the shaft is in a deployed position the deployable ground plane electrode extends substantially radially from a distal end of the shaft.

2. A surgical ablation system in accordance with claim 1, wherein the shaft includes an outer conductor coaxially disposed on an outer surface thereof.

3. A surgical ablation system in accordance with claim 2, wherein the outer conductor is electrically coupled to the deployable ground plane electrode.

4. A surgical ablation system in accordance with claim 1, wherein the deployable ground plane electrode further includes: at least one resilient wire element having a fixed end and a free end, wherein the fixed end thereof is fixed to a distal end of the shaft, a generally circular flexible ground plane membrane disposed upon the at least one resilient wire element.

5. A surgical ablation system in accordance with claim 4, wherein the at least one resilient wire element is configured to bias the ground plane membrane substantially radially from the shaft.

6. A surgical ablation system in accordance with claim 1, wherein the deployable ground plane electrode further includes: at least one resilient wire element loop having a first fixed end and a second fixed end, wherein the first fixed end and second fixed end thereof are fixed to a distal end of the shaft to form a generally semicircular loop; and a flexible ground plane membrane disposed upon the generally semicircular loop.

7. A surgical ablation system in accordance with claim 1, wherein the deployable ground plane electrode further includes: at least one resilient leaf element having a fixed end and a free end, wherein the fixed end thereof is fixed to a distal end of the shaft; and a conductive element disposed on a surface of the resilient leaf element.

8. A surgical ablation system in accordance with claim 7, further comprising a dielectric coating disposed on the conductive element.

9. A surgical ablation probe, comprising: a cannula having a proximal end and a distal end; a shaft slidably disposed within the cannula and having at least a stowed position and a deployed position; an inner conductor coaxially disposed within the shaft and extending from a distal end thereof to form a needle electrode; and a deployable ground plane electrode assembly disposed about a distal end of the shaft, wherein when the shaft is in a stowed position, the deployable ground plane electrode is substantially contained within the cannula, and when the shaft is in a deployed position the deployable ground plane electrode extends substantially radially from a distal end of the shaft.

10. A surgical ablation system in accordance with claim 9, wherein the shaft includes an outer conductor coaxially disposed on an outer surface thereof.

11. A surgical ablation system in accordance with claim 10, wherein the outer conductor is electrically coupled to the deployable ground plane electrode.

12. A surgical ablation system in accordance with claim 9, wherein the deployable ground plane electrode further includes: at least one resilient wire element having a fixed end and a free end, wherein the fixed end thereof is fixed to a distal end of the shaft, a generally circular flexible ground plane membrane disposed upon the at least one resilient wire element.

13. A surgical ablation system in accordance with claim 12, wherein the resilient wire element is formed from material selected from the group consisting of shape memory alloy, nitinol, stainless steel, and platinum.

14. A surgical ablation system in accordance with claim 12, wherein the ground plane membrane is formed from material selected from the group consisting of metallic foil, metallic mesh, and metal-coated polymeric film.

15. A surgical ablation system in accordance with claim 12, wherein the at least one resilient wire element is configured to bias the ground plane membrane substantially radially from the shaft.

16. A surgical ablation system in accordance with claim 9, wherein the deployable ground plane electrode further includes: at least one resilient wire element loop having a first fixed end and a second fixed end, wherein the first fixed end and second fixed end thereof are fixed to a distal end of the shaft to form a generally semicircular loop; and a flexible ground plane membrane disposed upon the generally semicircular loop.

17. A surgical ablation system in accordance with claim 9, wherein the deployable ground plane electrode further includes: at least one resilient leaf element having a fixed end and a free end, wherein the fixed end thereof is fixed to a distal end of the shaft; and a conductive element disposed on a surface of the resilient leaf element.

18. A surgical ablation system in accordance with claim 17, further comprising a dielectric coating disposed on the conductive element.

19. A surgical ablation system in accordance with claim 17, wherein the at least one resilient leaf element is formed from material selected from the group consisting of metal, polymeric material, shape memory metal, shape memory polymeric material, and polyimide.

20. A method of using a surgical ablation system, comprising: positioning an ablation probe at an operative site, wherein the ablation probe includes a cannula having therein a deployable ground plane antenna and a distal needle electrode; deploying the ground plane antenna and distal needle electrode; delivering electrosurgical energy to tissue via the needle electrode to facilitate the insertion of the needle electrode into tissue; inserting the needle electrode into tissue; delivering ablation energy to tissue via the needle electrode; withdrawing the needle electrode from tissue; retracting the ground plane antenna into the cannula; and removing the ablation probe from the operative site.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which:

[0017] FIG. 1 is a schematic representation of a microwave ablation system that includes an ablation probe having a deployable ground plane in accordance with the present disclosure;

[0018] FIG. 2 is a side, cutaway view of an embodiment of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure

[0019] FIG. 3 is a side, partial cutaway view of an embodiment of a microwave ablation probe having a deployable ground plane, in a first position, in accordance with the present disclosure;

[0020] FIG. 4 is a side, partial cutaway view of an embodiment of a microwave ablation probe having a deployable ground plane, in a second position, in accordance with the present disclosure;

[0021] FIG. 5 is a side, partial cutaway view of an embodiment of a microwave ablation probe having a deployable ground plane, in a third position, in accordance with the present disclosure;

[0022] FIG. 6 is a side, partial cutaway view of an embodiment of a microwave ablation probe having a deployable ground plane, in a fourth position, in accordance with the present disclosure;

[0023] FIG. 7 is distal end view of an embodiment of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure;

[0024] FIG. 7A is edge, cross sectional view of an embodiment of ground plane assembly in accordance with the present disclosure;

[0025] FIG. 8 is distal end view of another embodiment of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure;

[0026] FIG. 9 is distal end view of yet another embodiment of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure;

[0027] FIG. 10 is distal end view of still another embodiment of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure;

[0028] FIG. 10A is a perspective view of the FIG. 10 embodiment of a microwave ablation probe having a deployable ground plane assembly in a closed position, in accordance with the present disclosure;

[0029] FIG. 10B is a perspective view of the FIG. 10 embodiment of a microwave ablation probe having a deployable ground plane assembly in an open position, in accordance with the present disclosure;

[0030] FIG. 11 is distal end view of a further embodiment of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure;

[0031] FIGS. 12A-12J illustrate a method of use of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure;

[0032] FIG. 13A illustrates an embodiment of a ground plane leaf having a conductive element disposed thereupon in accordance with the present disclosure; and

[0033] FIG. 13B illustrates another embodiment of a ground plane leaf having a conductive element disposed thereupon in accordance with the present disclosure.

DETAILED DESCRIPTION

[0034] Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms. Well-known and/or repetitive functions and constructions are not described in detail to avoid obscuring the present disclosure in unnecessary or redundant detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. In addition, as used herein, the term proximal shall refer to the end of the instrument that is closer to the user, while the term distal shall refer to the end that is farther from the user, as is customary.

[0035] FIG. 1 shows an embodiment of a microwave ablation system 10 in accordance with the present disclosure. The microwave ablation system 10 includes an electromagnetic surgical ablation probe 5 operatively coupled by a cable 15 to connector 16, which may further operably couple the antenna probe 10 to a selector switch 22, which, in turn, selectively and operably couples an ablation generator assembly 20 and/or an electrosurgical generator assembly 18 to probe 10. Switch 22 may be any suitable switching device, including without limitation a mechanical switch, relay, semiconductor, and/or combinations thereof. Ablation generator 20, electrosurgical generator 18, and/or switch 22 may be operably coupled to a controller 24. Probe 10 includes a distal radiating portion 11 having a generally shallow umbrella-shaped ground plane 12 disposed thereupon. As depicted in FIG. 1, ground plane 12 is in a deployed position. A needle electrode 13 extends distally from the probe 10, which is also depicted in FIG. 1 in a deployed position. Ablation generator assembly 20 is a source of ablation energy, e.g., microwave or RF energy in a range of about 300 MHz to about 10 GHz. In embodiments, generator assembly 20 may provide ablation energy in a range of about 915 MHz to about 2.45 GHz. Electrosurgical generator 18 is a source of electrosurgical energy in a range of about 200 kHz to 3.3 MHz range and configured to provide one or more electrosurgical waveforms adapted to facilitate cutting, coagulating, blending, etc. Electrosurgical generator 18 may include a return electrode input (not explicitly shown) to accommodate a return electrode pad that is used during monopolar electrosurgical procedures.

[0036] With reference to FIGS. 2 and 3, a coaxial fed microwave ablation probe 100 is shown. The disclosed probe 100 includes a shaft assembly 110 slidably disposed within a cannula 112. The shaft 110 includes an inner conductor 101 disposed coaxially within dielectric 102, and an outer conductor 103 coaxially disposed around the dielectric 102. The inner conductor 101 extends distally from the dielectric 102 to form a needle electrode 104, which may include a sharpened distal tip 105 to ease the insertion thereof into tissue. As shown in FIGS. 2 and 3, distal tip is substantially aligned with a distal end 113 of trocar 112.

[0037] Shaft 110 includes an umbrella-like deployable ground plane electrode assembly 120 disposed generally at a distal end 106 of dielectric 102. The umbrella-like deployable ground plane assembly 120 includes a plurality of wire elements 121, each having a fixed end 123 and a free end 124. The umbrella-like deployable ground plane 120 assembly is movable between a stowed position, as seen generally in FIGS. 2 and 3, and a deployed position as seen in FIG. 6. The wire elements may be formed from any suitable resilient material having sufficient flexibility to be stowed in a first position while having sufficient elasticity to recover to a deployed position as shown in FIG. 6. For example, and without limitation, wire elements 121 may be formed from shape memory alloy (e.g., nitinol), stainless steel, platinum, or other material exhibiting similar elastic and recovery characteristics.

[0038] A fixed end 123 of each wire element 121 may be fixed to a distal end 106 of dielectric 102 such that, in a deployed position, a wire element 121 extends substantially radially from (orthogonal to) shaft 110. Fixed end 123 of wire element 121 may be joined to dielectric 102 by any suitable manner of connection, including without limitation by mechanical and/or interference fit into a corresponding opening (not explicitly shown) defined within dielectric 102, and/or by soldering, welding, brazing, adhesive coupling, and the like. Additionally or alternatively, a fixed end 123 of each wire element 121 may be fixed to a distal end of outer conductor 103 and operably electrically coupled thereto.

[0039] A flexible ground plane membrane 122 is disposed in electrical communication onto the plurality of wire elements 121 of umbrella-like deployable ground plane assembly 120. Ground plane membrane 122 may be formed from any electrically conductive material having sufficient flexibility, strength and heat resistance to enable the deployment and/or retrieval of ground plane assembly 120, such as, without limitation, metallic foil, metallic mesh, and/or metal-coated polymers, e.g., aluminized biaxially-oriented polyethylene terephthalate (a.k.a, boPET or Mylar).

[0040] In a stowed or closed position, best illustrated in FIGS. 2 and 3, the ground plane assembly 120 is folded such that free ends 124 of wire elements 121 may be positioned substantially adjacent to or in contact with shaft 110 at a location proximal of a distal end of dielectric 102. An outward, or opening, bias of the wire elements 121 is resisted by the cannula 112 to confine ground plane assembly 120 to a stowed position. Ground plane assembly 120 may be moved to a deployed position as seen in FIGS. 4-6 by advancing the shaft 110 distally in relation to cannula 112, and/or, withdrawing cannula 112 proximally with respect to shaft 110.

[0041] As seen in FIG. 4, shaft 110 has been moved distally with respect to cannula 112, thereby exposing a distal portion of ground plane assembly 120. An inner surface of cannula 112 may include a lubricious coating, such as without limitation, polytetrafluoroethylene (PTFE) (e.g., Teflon, manufactured by E. I. du Pont de Nemours and Company of Wilmington, Del., United States), which may facilitate movement of shaft 110 and/or ground plane assembly 120 within cannula 112. As shown in FIG. 4, a proximal portion (e.g., the free ends 124) of closed ground plane assembly 120 remains within cannula 112, thereby retaining ground plane antenna 120 in a closed position. Turning now to FIG. 5, shaft 110 is moved further distally, moving ground plane assembly 120 clear of cannula 112 and thus enabling wire elements 121 to recover to a relaxed position, which causes ground plane 120 to open into a deployed position best seen in FIGS. 6 and 7. It is envisioned that the deployment of ground plane assembly 120 (once clear of cannula 112) may occur in a generally instantaneous motion or in a gradual motion. In embodiments, the deployment time of ground plane assembly 120 may range from less than 50 milliseconds to about five seconds.

[0042] Ground plane assembly 120 may include a dielectric coating on a surface thereof, e.g., a distal surface, a proximal surface, or an edge thereof (as referenced to a ground plane assembly in an open or deployed position). Additionally or alternatively, ground plane membrane 122 may include a plurality of layers and/or laminations, as shown in FIG. 7A. In one envisioned embodiment, at least one inner surface 125 between layer 122a and 122b includes a metallic coating. An outer surface 126a and/or 126b includes a dielectric coating. It is also envisioned that a layer 122a and/or 122b may be formed from a dielectric material, such as without limitation PTFE, or boPET (e.g., Mylar, manufactured by E. I. du Pont de Nemours and Company of Wilmington, Del., United States).

[0043] Additional envisioned embodiments of a ground plane assembly in accordance with the present disclosure are discussed with reference to FIGS. 8-11. As seen in FIG. 8, a ground plane assembly includes one or more leaf-like ground plane elements 224 radially disposed about a dielectric distal end 206. Each ground plane element 224 includes a wire element 221 having two fixed ends 223 that are operably fixed to a dielectric distal end 206 as described hereinabove to form a petal-like wire loop 225. A ground plane membrane 222 is disposed upon each wire loop 225 to form a ground plane element 224. Each ground plane element may be stowed within a cannula (not explicitly shown) in a closed position, and deployed at an operative site into an open position as described herein.

[0044] In FIG. 9, an alternative ground plane assembly 240 is depicted wherein one or more ground plane elements 224 are disposed in an asymmetrical radial arrangement. Such an asymmetrical arrangement may provide alternative ablation patterns which may be desirable in particular surgical scenarios, e.g., wherein irregularly-shaped or asymmetrical tumors or lesions are targeted. In an embodiment, wire element 241 may include a score (not explicitly shown) at a juncture 243 where wire element 241 is joined to dielectric distal end 207. A user (e.g., a surgeon) may tailor a ground plane assembly 240 by bending unwanted ground plane elements 244 at the score until the wire element 241 breaks, thus enabling the removal of individual ground plane elements 244 from the ground plane assembly 240. In this manner, the ablation pattern and/or physical dimensions of the ground plane assembly and probe associated therewith may be adapted to the particular requirements of a surgical procedure.

[0045] Yet another embodiment is described herein with reference to FIGS. 10, 10A, and 10B, wherein a microwave ablation probe 300 includes a ground plane assembly 320 having one or more deployable ground plane leaves 322 disposed in a radial arrangement to a dielectric distal end 306 of probe 300. Leaves 322 may be formed from resilient substrate material, e.g., shape memory alloy sheet material, shape memory polymeric sheet material, and/or resilient polymeric sheet material, such as without limitation, polyimide, e.g., Kapton film manufactured by E. I. du Pont de Nemours and Company of Wilmington, Del., United States. Leaves 322 may have a laminated construction, wherein in an embodiment, a substrate material may include a dielectric coating on an outer surface thereupon to form an insulating layer between a substrate material and tissue. In yet another embodiment illustrated in FIG. 13A, a leaf 360 may be formed from a non-metallic substrate 361, which may include one or more conductive elements 362 disposed thereupon having a substantially solid pattern. As seen in FIG. 13B, a leaf 370 may include one or more conductive elements 372 (e.g., circuit traces) arranged in a generally serpentine pattern, which may enhance or control ablation volumes. A contact region 363, 373 may additionally or alternatively be included to facilitate electrical and/or mechanical coupling of a leaf 360, 370 to an associated probe (e.g., a dielectric and/or outer conductor thereof). The disclosed conductive elements may provide a ground plane electrode and/or may be formed from resistance metal, e.g., nickel-chromium resistance metal (a.k.a. nichrome), through which an electric current may be passed. The electric current causes heating of the resistance metal which, in turn, causes heating of a shape memory substrate layer associated therewith, to activate shape memory material transformation to facilitate deployment of the ground plane electrode.

[0046] In a further embodiment illustrated in FIG. 11, a ground plane assembly 340 includes one or more leaves 341-348 of varying shapes and/or sizes, which may improve or control an ablation pattern of a ground plane assembly and/or an associated probe, and which may tailor ablation performance to particular requirements of a surgical procedure.

[0047] Turning now to FIGS. 12A-12J, a method of use of a microwave ablation probe having a deployable ground plane in accordance with the present disclosure is described. With reference to FIGS. 12A and 12B, the disclosed method includes the steps of providing to targeted tissue T at a surgical site a cannula 401 having stowed therein an ablation probe 402 that includes a deployable ground plane electrode 403 and a needle electrode 404. As seen in FIGS. 12B and 12C, the cannula 401 is retracted relative to the probe 402 to expose the deployable ground plane 403. Additionally or alternatively, the probe 402 may be advanced with respect to the cannula 401 and/or targeted tissue T. As the retraction of cannula 401 and/or the advancement of probe 402 proceeds, deployable ground plane 403 is exposed completely causing the deployment thereof into an open position as shown in FIGS. 12D and 12E.

[0048] The probe 402, and optionally the cannula 401, are advanced toward the targeted tissue T thereby inserting needle electrode 404 into the targeted tissue and/or bringing ground plane 403 into contact with a surface thereof as shown in FIG. 12F. Electrosurgical energy may be applied via needle electrode 404 to facilitate the insertion thereof into targeted tissue T. Probe 402 is then energized to deliver ablation energy to tissue T via, e.g., needle electrode 404. The probe 402 is then retracted and needle electrode 404 removed from tissue T as shown in FIG. 12G. Probe 402 continues to be retracted into cannula 401, causing ground plane 403 to fold forward, and slide into cannula 401 as depicted in FIGS. 12H and 121. Cannula 401 is then withdrawn from tissue T as shown in FIG. 12J.

[0049] It is envisioned the steps of the above method may be performed in a different order than that described, and/or the operations performed within an individual step or steps may be desirably be combined into a single step without departing from the scope and spirit of the method disclosed herein. For example, and without limitation, needle electrode 404 may be inserted into targeted tissue prior to deployment of ground plane 403, which may result in ground plane 403 to contact tissue T substantially immediately upon deployment. In another example, and without limitation, once probe 402 is retracted into cannula 401, causing ground plane 403 to fold forward, as depicted in FIGS. 12H, 121, and 12J, subsequent retraction of cannula 401 relative to probe 402 results in the free end of ground plane 403 to be exposed from cannula 401 prior to the fixed end of ground plane 403.

[0050] The described embodiments of the present disclosure are intended to be illustrative rather than restrictive, and are not intended to represent every embodiment of the present disclosure. Further variations of the above-disclosed embodiments and other features and functions, or alternatives thereof, may be made or desirably combined into many other different systems or applications without departing from the spirit or scope of the disclosure as set forth in the following claims both literally and in equivalents recognized in law.