ELECTROSURGICAL INSTRUMENT

Abstract

An electrosurgical device having a radiating tip portion for delivering electromagnetic energy to biological tissue, where the electrosurgical device is disposed in a catheter. The electrosurgical device is movable relative to the catheter between a deployed position where the radiating tip portion is exposed and a retracted position where the radiating tip portion is contained within the catheter. In this manner, the radiating tip portion may be retracted until the moment when it is to be used. This may facilitate insertion of the device through an instrument channel of a surgical scoping device. In particular, this may prevent the radiating tip portion from catching on the instrument channel when the device is inserted into the instrument channel, which could cause damage to the instrument channel and/or radiating tip portion.

Claims

1. An electrosurgical instrument comprising: a flexible catheter having a lumen extending therethrough, the catheter being dimensioned to be insertable through an instrument channel of a surgical scoping device; and an electrosurgical device disposed within the lumen, the electrosurgical device comprising: a flexible coaxial cable configured to convey microwave energy; and a radiating tip portion connected at a distal end of the coaxial cable to receive the microwave energy, the radiating tip portion having a smaller outer diameter than the flexible coaxial cable, wherein the radiating tip portion comprises: a proximal coaxial transmission line for conveying the microwave energy; and a distal needle tip at a distal end of the proximal coaxial transmission line, the distal needle tip being configured to radiate the microwave energy into biological tissue, wherein the electrosurgical device is longitudinally movable within the lumen between a deployed position in which the distal needle tip protrudes beyond a distal end of the catheter, and a retracted position in which the distal needle tip portion is contained within the catheter.

2. An electrosurgical instrument according to claim 1, wherein the distal needle tip is configured to operate as a half wavelength transformer to deliver the microwave energy from the distal needle tip into biological tissue.

3. An electrosurgical instrument according to claim 1, wherein the catheter includes a constricted passageway at its distal end, the constricted passageway being dimensioned to permit passage of the radiating tip portion and to prohibit passage of the flexible coaxial cable.

4. An electrosurgical instrument according to claim 3, wherein the constricted passageway extends through a plug mounted at the distal end of the catheter.

5. An electrosurgical instrument according to claim 1, wherein a distal surface of the catheter is rounded.

6. An electrosurgical instrument according to claim 3, wherein the distal needle tip is retained in the constricted passageway when in the retracted position.

7. An electrosurgical instrument according to claim 1, wherein the distal needle tip comprises a pointed tip at its distal end.

8. An electrosurgical instrument according to claim 7, wherein the pointed tip is made of a rigid insulating material.

9. An electrosurgical instrument according to claim 7, wherein the distal needle tip comprises a distal dielectric sleeve around a central conductive element, and wherein the pointed tip is secured in a bore at a distal end of the distal dielectric sleeve.

10. An electrosurgical instrument according to claim 7, wherein the pointed tip is made of zirconia.

11. An electrosurgical instrument according to claim 1, wherein the proximal coaxial transmission line comprises an inner conductor separated from an outer conductor by a dielectric sleeve, wherein the inner conductor comprises a distal portion that protrudes beyond a distal end of the outer conductor, and wherein the distal needle tip comprises a length of the distal portion of the inner conductor.

12. An electrosurgical instrument according to claim 11, wherein the outer conductor of the proximal coaxial transmission line is made of nitinol.

13. An electrosurgical instrument according to claim 1, wherein the radiating tip portion is secured to the coaxial cable by a collar mounted over a junction therebetween, the collar having a distal surface that is rounded.

14. An electrosurgical instrument according to claim 1, wherein a length of the radiating tip portion is equal to or greater than 140 mm.

15. An electrosurgical instrument according to claim 1, wherein the radiating tip portion has a non-stick material on its outer surface.

16. An electrosurgical instrument according to claim 1, wherein a proximal portion of the coaxial cable is secured to a rigid reinforcing element.

17. An electrosurgical instrument according to claim 16, wherein a proximal portion of the lumen has a larger diameter than a distal portion of the lumen, to receive the proximal portion of the coaxial cable.

18. An electrosurgical instrument according to claim 1, wherein an inner conductor of the proximal coaxial transmission line is formed of an inner core made of a first conductive material and an outer conductive coating made of a second conductive material having a higher conductivity than the first conductive material.

19. A handpiece for controlling movement of an electrosurgical device along a lumen of a catheter, the handpiece comprising: a first section having a connector for connecting a distal end of the handpiece to an instrument port of a surgical scoping device; a second section connected to the first section and movable along a length of the first section, the second section having a holder for holding a proximal end of the catheter, whereby relative movement between the second section and first section is arranged to control a length of catheter that extends out of a distal end of the handpiece; and a third section connected to the second section and movable along a length the second section, the third section having a coaxial connector arranged to receive a proximal end of a coaxial cable that is conveyed within the lumen of the catheter, whereby relative movement between the third section and second section is arranged to control a relative position of the coaxial cable within the catheter.

20. A handpiece according to claim 19, wherein the second section has a fixing mechanism for fixing a position of the second section relative to the first section.

21. A handpiece according to claim 19, wherein the second section includes a limiter that is movable along a length of the second section, and wherein the limiter is arranged to restrict motion of the third section relative to the second section.

22. A handpiece according to claim 19, wherein the first section and the second section are telescopically arranged, the second section being slidable along the length of the first section.

23. A handpiece according to claim 19, wherein the second section and the third section are telescopically arranged, the third section being slidable along the length of the second section.

24. An electrosurgical system for treating biological tissue, the system comprising: an electrosurgical generator arranged to supply microwave energy; a surgical scoping device having a flexible insertion cord for insertion into a patient's body, wherein the flexible insertion cord has an instrument channel running along its length; an electrosurgical instrument according to claim 1, wherein the electrosurgical instrument is dimensioned to fit within the instrument channel; and a handpiece, the handpiece comprising: a first section having a connector for connecting a distal end of the handpiece to an instrument port of a surgical scoping device; a second section connected to the first section and movable along a length of the first section, the second section having a holder for holding a proximal end of the catheter, whereby relative movement between the second section and first section is arranged to control a length of catheter that extends out of a distal end of the handpiece; and a third section connected to the second section and movable along a length the second section, the third section having a coaxial connector arranged to receive a proximal end of a coaxial cable that is conveyed within the lumen of the catheter, whereby relative movement between the third section and second section is arranged to control a relative position of the coaxial cable within the catheter; wherein a proximal end of the catheter of the electrosurgical instrument is held in the holder, a proximal end of the coaxial cable of the electrosurgical instrument is received in the coaxial connector, and the coaxial connector is connected to the electrosurgical generator to receive the microwave energy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Embodiments of the invention are discussed below with reference to the accompanying drawings, in which:

[0069] FIG. 1 is a schematic diagram of an electrosurgical system that is an embodiment of the invention;

[0070] FIGS. 2a and 2b show schematic cross-sectional views of an electrosurgical instrument that is an embodiment of the invention, where in FIG. 2a an electrosurgical device of the instrument is in a retracted position and in FIG. 2b the electrosurgical device of the instrument is in a deployed position;

[0071] FIG. 3a is a perspective view of the electrosurgical instrument of FIGS. 2a and 2b;

[0072] FIG. 3b is a perspective view of the electrosurgical instrument of FIGS. 2a and 2b, where a catheter of the instrument has been omitted to reveal an internal structure of the instrument;

[0073] FIG. 4 is a perspective view of the electrosurgical instrument of FIGS. 2a and 2b;

[0074] FIGS. 5 and 6 are schematic side views of an electrosurgical device that is a part of an electrosurgical instrument of an embodiment of the invention;

[0075] FIG. 7 shows a schematic cross-sectional view of a distal needle tip of an electrosurgical instrument that is an embodiment of the invention;

[0076] FIG. 8 shows a schematic view of a distal needle tip of an electrosurgical instrument that is an embodiment of the invention;

[0077] FIGS. 9a and 9b are schematic cross-sectional views depicting deformation of respective examples of an electrosurgical instrument when inserted through an instrument channel that is in retroflex;

[0078] FIG. 10 shows a schematic cross-sectional view of a handpiece that is an embodiment of the invention;

[0079] FIGS. 11 and 12 show perspective views of the handpiece of FIG. 10, where in FIG. 11 parts of components of the handpiece have been omitted to reveal an internal structure of the handpiece;

[0080] FIGS. 13a and 13b show plan views of the handpiece of FIG. 10 with the distal needle in a retracted and extended (deployed) position, respectively;

[0081] FIG. 14a is a cross-sectional view of a catheter that is part of an electrosurgical instrument that is an embodiment of the invention; and

[0082] FIG. 14b is a cross-sectional view of a catheter that is part of an electrosurgical instrument that is another embodiment of the invention.

DETAILED DESCRIPTION; FURTHER OPTIONS AND PREFERENCES

[0083] FIG. 1 is a schematic diagram of an electrosurgical ablation apparatus 100 that is capable of supplying microwave energy and/or radiofrequency energy to the distal end of an invasive electrosurgical instrument. The system 100 comprises a generator 102 for controllably supplying microwave energy and radiofrequency energy. A suitable generator for this purpose is described in WO 2012/076844, which is incorporated herein by reference. The generator may be arranged to monitor reflected signals received back from the instrument in order to determine an appropriate power level for delivery. For example, the generator may be arranged to calculate an impedance seen at the distal end of the instrument in order to determine an optimal delivery power level.

[0084] The generator 102 is connected to a handpiece 106 by an interface cable 104. In other examples (not shown), the handpiece 106 may also be connected via a fluid flow line to a fluid delivery device, such as a syringe, e.g. where it is desired to convey fluid to the distal end of the electrosurgical instrument.

[0085] The handpiece 106 houses an instrument control mechanism that is operable to control longitudinal (back and forth) movement of the electrosurgical instrument. The handpiece 106 may also house control mechanisms (e.g. triggers) for actuating one or more control wires or push rods, if necessary. An example handpiece is described in more detail below, in relation to FIGS. 10-12. A function of the handpiece is to combine the input from the generator 102 and any other inputs into an integrated flexible instrument cable which exits from a distal end of the handpiece 106 and is dimensioned to be conveyed through an instrument channel of a surgical scoping device.

[0086] The handpiece 106 is connected to an input port 128 of a surgical scoping device 114. The surgical scoping device 114 comprises a body 116 having a number of input ports and an output port from which an instrument cord 120 extends. The instrument cord 120 comprises an outer jacket which surrounds a plurality of lumens. The plurality of lumens convey various things from the body 116 to a distal end of the instrument cord 120. One of the plurality of lumens is the instrument channel through with the instrument cable extends. Other lumens may include a channel for conveying optical radiation, e.g. to provide illumination at the distal end or to gather images from the distal end, and an ultrasound signal channel for conveying an ultrasound signal. The body 116 may include an eye piece 122 or other imaging device that enables viewing the distal end.

[0087] An endoscopic ultrasound device typically includes an ultrasound transducer on a distal tip of the instrument cord, beyond an exit aperture of the ultrasound signal channel. Signals from the ultrasound transducer may be conveyed by a suitable cable 126 back along the instrument cord to a processor 124, which can generate images in a known manner. The instrument channel may be shaped within the instrument cord to direct an instrument exiting the instrument channel through the field of view of the ultrasound system, to provide information about the location of the instrument at the target site.

[0088] The integrated flexible instrument cable exits from the distal end of the handpiece 106, and is received within the instrument channel in the instrument cord 120 of the surgical scoping device 114. The integrated flexible instrument cable has a distal assembly 118 (not drawn to scale in FIG. 1) that is shaped to pass through the instrument channel of the surgical scoping device 114 and protrude (e.g. inside the patient) at the distal end of the instrument cord 120.

[0089] The structure of the distal assembly 118 discussed below may be particularly designed for use with an endoscopic ultrasound (EUS) device, whereby the maximum outer diameter of the distal end assembly 118 is equal to or less than 1.2 mm, e.g. less than 1.0 mm and the length of the electrosurgical instrument can be equal to or greater than 1.2 m.

[0090] It is desirable to be able to control the position of at least the distal end of the instrument cord 120. The body 116 may include a control actuator that is mechanically coupled to the distal end of the instrument cord 120 by one or more control wires (not shown), which extend through the instrument cord 120. The control wires may travel within the instrument channel or within their own dedicated channels. The control actuator may be a lever or rotatable knob, or any other known catheter manipulation device. The manipulation of the instrument cord 120 may be software-assisted, e.g. using a virtual three-dimensional map assembled from computer tomography (CT) images.

[0091] An electrosurgical instrument 200 according to an embodiment of the invention is illustrated in FIGS. 2a, 2b, 3a, 3b and 4. The electrosurgical instrument 200 includes an integrated instrument cable comprising an electrosurgical device 202 disposed in a catheter 204. The catheter 204 defines a lumen in which the electrosurgical device 202 is received, and along which the electrosurgical device 202 is movable. The electrosurgical device 202 is movable along the catheter between a retracted position, which is shown in FIG. 2a, and a deployed position, which is shown in FIG. 2b. FIGS. 2a and 2b show schematic cross-sectional side views of the electrosurgical instrument 200; FIG. 3a shows a perspective view of the instrument 200 where, for illustration purposes, the catheter 204 is shown as transparent to reveal the electrosurgical device 202 inside the catheter 204; and FIG. 3b shows a perspective view of the instrument 200 where, for illustration purposes, the catheter 204 has been omitted. FIG.

[0092] 4 shows a perspective view of the electrosurgical instrument where the electrosurgical device 202 is in the deployed position.

[0093] The electrosurgical device 202 is illustrated in more detail in FIGS. 5 and 6. The electrosurgical device 202 includes a flexible coaxial cable 206 and a radiating tip portion 208, which is connected at a distal end of the coaxial cable 206. The coaxial cable 206 may be a conventional flexible 50 Ω coaxial cable suitable for conveying microwave and radiofrequency energy. The coaxial cable includes a centre conductor and an outer conductor that are separated by a dielectric material. The coaxial cable 206 is connectable at a proximal end to a generator, e.g. to generator 102, to receive microwave and/or radiofrequency energy.

[0094] The radiating tip portion 208 includes a proximal coaxial transmission line 210 and a distal needle tip 212 formed at a distal end of the proximal coaxial transmission line 210. The proximal coaxial transmission line 210 is electrically connected to the distal end of the coaxial cable 206 to receive the electromagnetic energy from the coaxial cable 206 and convey it to the distal needle tip 212. The distal needle tip 212 is configured to deliver the received electromagnetic energy into target biological tissue. In the example shown, the distal needle tip 212 is configured as a half wavelength transformer to deliver microwave energy into target biological tissue, to ablate the target tissue.

[0095] An inner conductor 214 of the proximal coaxial transmission line 210 is electrically connected to the centre conductor of the coaxial cable 206. The radiating tip portion 208 is secured to the coaxial cable 206 via a collar 216 mounted over a junction between the coaxial cable 206 and the radiating tip portion 208. The collar 216 is made of a conductive material (e.g. brass), and electrically connects the outer conductor of the coaxial cable 206 to an outer conductor 218 of the proximal coaxial transmission line 210. The outer conductor 218 is formed of a tube of nitinol.

[0096] The collar 216 includes a substantially cylindrical body 219 which is mounted on the distal end of the coaxial cable 206 and which is electrically connected to the outer conductor of the coaxial cable 206. The collar 216 further includes a distal portion 220 which extends from the body 219 of the collar 216 to a proximal end of the outer conductor 218 of the proximal coaxial transmission line 210. The distal portion 220 of the collar 216 includes a distal surface which is rounded. This may reduce friction between the electrosurgical device 202 and the catheter 204 when the electrosurgical device 202 is moved along the catheter 204, by avoiding sharp edges at the interface between the coaxial cable 206 and the radiating tip portion 208. This may also facilitate moving the electrosurgical device 202 along the catheter 204 when the catheter 204 is in retroflex.

[0097] The radiating tip portion 208 has a smaller outer diameter than the coaxial cable 206. This may enable the radiating tip portion 208 to be more flexible than the coaxial cable 206, which may facilitate bending of the radiating tip portion 208 and/or guiding of the radiating tip portion to an awkward treatment site. Making the outer diameter of the radiating tip portion 208 smaller may also reduce the size of an insertion hole made when the radiating tip portion 208 is inserted into tissue, which may minimise bleeding and facilitate healing. Preferably, the radiating tip portion may have an outer diameter that is 1.2 mm or less, e.g. 1.0 mm or 0.9 mm. The coaxial cable 206 may have an outer diameter that is around 2.0 mm.

[0098] The catheter 204 is a flexible tube made of an insulating material (e.g. PEEK or PTFE). The catheter 204 is dimensioned to be insertable into the working channel of a surgical scoping instrument. The catheter 204 defines a lumen in which the electrosurgical device 202 is received, and along which the electrosurgical device 202 is movable.

[0099] A plug 222 is mounted at a distal end of the catheter 204. The plug 222 has a body portion 224 which is disposed inside the distal end of the catheter 204. The body portion 224 includes a barb (or bulge) 226 disposed on an outer surface of the body portion 224, which forms an interference fit with the catheter 204, in order to secure the plug 222 at the distal end of the catheter 204. In this manner, the plug 222 may be secured at the distal end of the catheter 204 without having to use adhesive (although adhesive may be used to further secure the plug 222 to the catheter 204). A distal surface 228 of the plug 222, i.e. a surface exposed at the distal end of the catheter 204, is rounded. The rounded distal surface 228 of the plug 222 serves to avoid sharp edges around the distal end of the catheter 204. This may facilitate insertion of the electrosurgical device 200 along an instrument channel of a surgical scoping device, by reducing friction between the catheter 204 and the instrument channel at the distal end of the catheter 204. The plug may be made of PEEK or some other insulating material.

[0100] The plug 222 has a longitudinal passageway 230 defined therethrough. The passageway 230 is dimensioned to enable the radiating tip portion 208 to pass through it, but to prevent the coaxial cable 206 from passing through it. In this manner, the electrosurgical device 202 may be advanced along the catheter 204, to cause the radiating tip portion 208 to pass through the passageway so that a length of the radiating tip portion 208 protrudes beyond the distal end of the catheter 204 (e.g. as shown in FIG. 2b).

[0101] The passageway 230 includes a proximal opening 232 located at a proximal end of the body portion 224 inside the catheter 204. A distal opening 234 of the passageway 230 is located in the distal surface 228 of the plug 222. When the electrosurgical device 202 is in the deployed position (e.g. FIG. 2b), the radiating tip portion 208 protrudes through the distal opening 234 of the passageway 230. A length of the passageway 230 is greater than a length of the distal needle tip 212, i.e. a distance between the proximal opening 232 and the distal opening 234 of the passageway 230 is greater than the length of the distal needle tip 212. In this manner, as shown in FIG. 2a, when the electrosurgical device 202 is in the retracted position, the distal needle tip 212 may be entirely contained within the passageway 230 in the plug 222. In particular, a lip 236 formed by a distal end of the outer conductor 218 may be located inside the passageway 230 when the electrosurgical device 202 is in the retracted position. This may prevent the lip 236 from catching on the proximal opening 232 of the passageway 230 when the electrosurgical device 202 is moved from the retracted position to the deployed position.

[0102] The lip 236 of the outer conductor 218 is chamfered, e.g. sloped, to further prevent the lip 236 from catching on the proximal opening 232 of the passageway 230. The proximal opening 232 of the passageway is flared outwards, i.e. a diameter of the opening 232 increases in the proximal direction. In this manner, the flared proximal opening 232 acts to funnel the radiating tip portion 208 into the passageway, to avoid the radiating tip portion 208 from catching on the proximal opening 232 and to facilitate moving the radiating tip portion 208 through the passageway 230.

[0103] The passageway 230 serves to guide the radiating tip portion 208 as the electrosurgical device 202 is moved between the retracted and deployed positions. The passageway 230 is centred about a longitudinal axis of the catheter 204, such that the passageway 230 acts to centralise the radiating tip portion 208 when the radiating tip portion 208 is moved through the passageway 230.

[0104] In FIG. 2a, the electrosurgical device 202 is in the retracted position, with the distal needle tip 212 located within the passageway 230 in the plug 222. This means that the radiating tip portion 208 does not protrude from the catheter 204. In this configuration, the radiating tip portion 208 is therefore protected by the catheter 204 and the plug 222. The electrosurgical instrument 200 may be inserted into the instrument channel of a surgical scoping device and guided into position with the electrosurgical device 202 in the retracted position. This may facilitate inserting the electrosurgical instrument 200 into the instrument channel, as it prevents the radiating tip portion 208 from catching in the instrument channel.

[0105] Once the electrosurgical instrument 200 has been guided to a desired position, the electrosurgical device 202 may be moved into the deployed position. From the retracted position shown in FIG. 2a, this may be achieved by moving the electrosurgical device 202 in a distal direction along the catheter 204, to cause the radiating tip portion 208 to protrude through the distal opening 234 of the passageway 230 in the plug 222. The electrosurgical device 202 may be moved until the deployed position showed in FIG. 2b is reached. As the electrosurgical device 202 protrudes from the distal opening 234 of the passageway 230, the radiating tip portion 208 may be inserted into biological tissue. Once the distal needle tip 212 reaches a target treatment site (e.g. a tumour), microwave energy may be delivered to the distal needle tip to ablate the target tissue.

[0106] Once the target tissue has been treated, the electrosurgical device 202 may be moved back into the retracted position so that the radiating tip portion 208 is no longer exposed. This is achieved by moving the electrosurgical device 202 along the catheter 204 in a proximal direction.

[0107] A sharp lip 238 is provided around the distal opening 234 of the passageway 230. The sharp lip 238 serves to scrape any tissue or blood that is stuck on the radiating tip portion 208 when the electrosurgical device 202 is moved from the deployed position to the retracted position. This may prevent tissue and or blood from being dragged into the catheter when the radiating tip portion 208 is pulled back into the catheter 204, which could contaminate the catheter 204 or impede movement of the electrosurgical device 202 in the catheter.

[0108] We will now describe the structure of the radiating tip portion 208 of the electrosurgical device 202 in more detail, with reference to FIGS. 5 and 6. For illustration purposes, the outer conductor 218 is omitted from FIG. 6, to reveal an inner structure of the radiating tip portion 208. Also for illustration purposes, a section of the proximal coaxial transmission line 210 has been omitted in FIGS. 5 and 6, as indicated by broken lines 502.

[0109] The proximal coaxial transmission line 210 includes a proximal dielectric sleeve 504 which is disposed around the inner conductor 214. The outer conductor 218 is formed on an outer surface of the proximal dielectric sleeve 504. A distal dielectric sleeve 506 is disposed around a distal portion of the inner conductor 214 to form the distal needle tip 212. The distal dielectric sleeve 506 is made of a different dielectric material compared to the proximal dielectric sleeve 504. In one example, the proximal dielectric sleeve 504 may be made of PTFE (e.g. it may be a PTFE tube) and the distal dielectric sleeve may be made of PEEK. A distal portion of the outer conductor 218 overlays a proximal portion of the distal dielectric sleeve 506. In this manner, a distal portion of the proximal coaxial transmission line 210 includes the proximal portion of the distal dielectric sleeve 506. The materials of the proximal and distal dielectric sleeves and the length of the overlap between the outer conductor 518 and the distal dielectric sleeve 506 may be selected in order to adjust an electrical length of the radiating tip portion 208 to assist with impedance matching to target tissue.

[0110] The outer conductor 218 may be made of nitinol, which is flexible and provides a sufficient longitudinal rigidity to pierce tissue (e.g. the duodenum wall). The inner conductor is made of a stainless steel core that is plated with a silver coating. The stainless steel core provides additional rigidity to the radiating tip portion 208, whilst the silver coating may increase the conductivity of the inner conductor 214 to reduce losses in the radiating tip portion 208.

[0111] A dielectric spacer 508 is mounted at the junction between the radiating tip portion 208 and the coaxial cable 206. The dielectric spacer 508 is disposed inside the collar 216, and is mounted around the inner conductor 214. In this manner, the dielectric spacer 508 is disposed between the inner conductor 214 and the collar 216. This may increase a breakdown distance between the inner conductor 214 and the collar 216 at the junction between the coaxial cable 206 and the radiating tip portion 208. This may improve electrical safety of the device at the junction. The dielectric spacer 508 may, for example, be a PTFE washer or a washer made of another suitable insulating material.

[0112] As mentioned above, the distal needle tip 212 is configured as a half wavelength transformer for delivering microwave energy into tissue. Thus, when microwave energy is delivered to the distal needle tip 212, the distal needle tip 212 may radiate the microwave energy into surrounding tissue. The distal needle tip 212 includes a pointed tip 510 at its distal end, to facilitate insertion of the radiating tip portion 208 into target tissue. The pointed tip 510 is made of a dielectric material having a higher rigidity than the distal dielectric sleeve 506. This may enable the pointed tip 510 to be sharper, and it may facilitate sharpening of the pointed tip 510. For example, the pointed tip 510 may be made of Zirconia.

[0113] FIG. 7 shows a more detailed view of the pointed tip 510 mounted at the distal end of the distal dielectric sleeve 506. The pointed tip 510 includes a tapered portion 702 which tapers to a fine point and which serves to pierce tissue. The pointed tip also includes a body 704 which extends from a proximal end of the tapered portion 702, and which is received in a bore at the distal end of the distal dielectric sleeve. The body 704 of the pointed tip 510 includes a protrusion (or bulge) 706 which forms an interference fit with a wall of the bore, in order to hold the body 704 in the bore. In this manner, a “push-fit” connection may be formed when the body 704 is inserted into the bore. This may enable the pointed tip 510 to be mounted in the distal dielectric sleeve 506 without adhesive. This may also facilitate exchanging the pointed tip 510, e.g. if the pointed tip 510 is damaged.

[0114] FIG. 8 shows an example of a different pointed tip 802 mounted at the distal end of the distal dielectric sleeve 506. The pointed tip 802 includes a body 804 which is disposed in the bore at the distal end of the distal dielectric sleeve 506. The body 804 includes a protrusion 806 for securing the body 804 in the bore. The pointed tip 802 further includes a tapered portion 808 which protrudes from the bore in the distal dielectric sleeve 506 and tapers to a fine point for piercing tissue. The tapered portion 808 includes a proximal portion 810 which is tapered at a first angle relative to the longitudinal direction, and a distal portion 812 which is tapered at a second, larger, angle relative to longitudinal direction. In this manner, the pointed tip 802 may be said to be “double-angled”. The fine point of the pointed tip 802 is formed by the distal portion 812. By making the tapering angle of the distal portion 812 larger than the tapering angle of the proximal portion 810, a length of the tapered portion 808 may be reduced. This may make the pointed tip 802 less fragile, and reduce the risk of the fine point of the pointed tip 802 breaking off.

[0115] In some embodiments (not shown), the pointed tip may be made of the same material as the distal dielectric sleeve, e.g. the pointed tip may be integrally formed with the distal dielectric sleeve. The concept using a double-angled pointed tip may be applied regardless of whether the pointed tip is formed integrally with or separately from the distal dielectric sleeve. In some embodiments (not shown), a single dielectric sleeve may be provided in place of the proximal and distal dielectric sleeves, e.g. the dielectric material in the proximal coaxial transmission line and the distal needle tip may be the same.

[0116] FIG. 9a shows a cross-sectional view of an electrosurgical instrument 900 according to an embodiment of the invention, where a distal portion of the instrument 900 is in retroflex. FIG. 9b shows a cross-sectional view of an electrosurgical instrument 902 according to another embodiment of the invention, where a distal portion of the instrument 902 is in retroflex.

[0117] Electrosurgical instruments 900 and 902 have a similar configuration to electrosurgical instrument 200 described above. Electrosurgical instrument 900 includes a catheter 904 in which an electrosurgical device 906 is disposed. The electrosurgical device 906 includes a coaxial cable 908 having a radiating tip portion 910 disposed at a distal end of the coaxial cable 908. The electrosurgical device 906 is movable along the catheter 904 between a retracted position where the radiating tip portion 910 is located within the catheter 904, and a deployed position where the radiating tip portion 910 protrudes from a distal end of the catheter 904. In the configuration shown in FIG. 9a, the electrosurgical device 906 is in the deployed position.

[0118] Similarly, electrosurgical instrument 902 includes an electrosurgical device 912 disposed in a catheter 914. The electrosurgical device 912 includes a coaxial cable 916 and a radiating tip portion 918 at a distal end of the coaxial cable 916. The electrosurgical device 912 is movable along the catheter 914 between a retracted position where the radiating tip portion 918 is located within the catheter 914, and a deployed position where the radiating tip portion 918 protrudes from a distal end of the catheter 914. In the configuration shown in FIG. 9b, the electrosurgical device 912 is in the deployed position.

[0119] In FIG. 9a, the distal portion 920 of the catheter 904 is in retroflex, i.e. the distal portion 920 of the catheter 904 is bent. As can be seen from FIG. 9a, a distal portion of the coaxial cable 908 is located in the distal portion 920 of the catheter 904, and is also bent. Therefore, in order to move the electrosurgical device 906 between the retracted position and the deployed position (shown in FIG. 9a), it is necessary to bend the distal portion of the coaxial cable 908. For example, when the electrosurgical device 906 is moved from the retracted position to the deployed position, the distal portion of the coaxial cable 908 must be pushed through the bent distal portion 920 of the catheter 904. When the electrosurgical device 906 is moved from the deployed position to the retracted position, the distal portion of the coaxial cable 908 must be unbent as it is pulled out of the bent distal portion 920 of the catheter 904.

[0120] Bending and unbending of the coaxial cable 908 may require a large force, due to the stiffness of the coaxial cable 908. Coaxial cables conventionally used in electrosurgical devices, such as the Sucoform 86 coaxial cable, have a relative stiff (e.g. heavily tinned) outer jacket. Whilst such an outer jacket may facilitate actuation of the device along a straight path, it may require a large force to bend the cable. As a result, when the distal portion of the catheter 904 is in retroflex, it may be necessary to apply a large force to the electrosurgical device 906 in order to move it between the retracted and deployed positions. This may result in a large amount of friction between the coaxial cable 908 and the catheter 904 in the bent portion 920, which may reduce the accuracy with which a position of the radiating tip portion 910 can be controlled.

[0121] The radiating tip portion 918 of electrosurgical device 912 (FIG. 9b) is longer than the radiating tip portion 910 of electrosurgical device 906 (FIG. 9a). As a result, when a distal portion 922 of the catheter 914 is bent (e.g. in retroflex, as shown in FIG. 9b), it may not be necessary to move the coaxial cable 916 through the bent portion 922 of the catheter 914 when the electrosurgical device 906 is moved to the deployed position. The radiating tip portion 918 may be more flexible than the coaxial cable 916, as the radiating tip portion 918 has a smaller diameter than the coaxial cable and does not have a rigid outer jacket. Thus, only a relatively small force may be required to bend the radiating tip portion 918 when it is moved through the bent distal portion 922 of the catheter 914.

[0122] As shown in FIG. 9b, by making the radiating tip portion 918 sufficiently long, the distal end of the coaxial cable 916 does not enter the bent distal portion 922 of the catheter 914 when the electrosurgical device 912 is in the deployed position, such that the distal end of the coaxial cable 916 does not need to be bent when moving the electrosurgical device 912 between the retracted and deployed positions. Preferably, the radiating tip portion may be 140 mm or longer. This may ensure that the coaxial cable 916 does not enter the retroflex portion of the catheter 914 when the electrosurgical device 912 is in the deployed position.

[0123] The configuration shown in FIG. 9b may thus reduce friction between the electrosurgical device 912 and the catheter 914 when the electrosurgical device 912 is moved along the catheter 914. This may improve control of the position of the radiating tip portion 918.

[0124] The electrosurgical device 912 further includes an outer sheath 924 disposed around a proximal portion of the radiating tip portion 918. The outer sheath 924 is made of or coated with a non-stick material, e.g. the outer sheath 924 may be a tube of PTFE. The outer sheath 924 may serve to reduce friction between the radiating tip portion 918 and the bent distal portion 922 of the catheter 914. This may facilitate moving the electrosurgical device 912 between the retracted and deployed positions. The outer sheath 924 may also serve to reduce lateral movement of the radiating tip portion 918 within the catheter, by acting as a spacer between the radiating tip portion 918 and the catheter 914. This may facilitate movement of the radiating tip portion along the bent distal portion 922 of the catheter 914.

[0125] FIG. 10 shows a cross-sectional diagram of a handpiece 1000 according to an embodiment of the invention. A perspective view of the handpiece 1000 is shown in FIG. 11, where parts of components of the handpiece 1000 have been removed to reveal an internal structure of the handpiece 1000. A further perspective view of the handpiece 1000 is shown in FIG. 12. The handpiece 1000 may be used with an electrosurgical instrument of the invention, e.g. electrosurgical instrument 200, 900, 902, in order to move the electrosurgical device of the instrument along the catheter of the instrument, between the retracted position and the deployed position.

[0126] The handpiece 1000 includes a first section 1002 which has a generally cylindrical hollow body 1004. A connector 1006 is provided at a distal end of the hollow body 1004, the connector 1006 being adapted to mount the handpiece onto an input port of an instrument channel of a surgical scoping device. The connector 1006 may be configured to mate with a corresponding connector on the input port. The connector 1006 may include a luer fitting (or some other suitable fitting), to provide a leak-free connection between the handpiece 1000 and the instrument channel of the surgical scoping device.

[0127] The handpiece 1000 further includes a second section 1008. The second section 1008 is formed of a generally cylindrical hollow body 1010 which is telescopically mounted on the first section 1002, such that the second section 1008 is longitudinally slidable over a length of the first section 1002. The second section 1008 includes a fixing screw 1012 for fixing the position of the second section 1010 relative to the first section 1002. The fixing screw 1012 is engaged in a threaded hole in a sidewall of the hollow body 1010. Tightening the fixing screw 1012 in the threaded hole causes the fixing screw 1012 to engage the body 1004 of the first section 1002 to fix the position of the second section 1010 relative to the first section 1002. Loosening the fixing screw 1012 in the threaded hole disengages the fixing screw from the first section 1002, so that the second section 1008 can be slid relative to the first section 1002.

[0128] The second section 1008 includes a holder 1014 disposed on an inside of the body 1010 of the second section 1008. The holder 1014 is configured to hold a proximal end of a catheter of an electrosurgical instrument. The holder 1014 may, for example, be a clip or a clamp arranged to hold the proximal end of the catheter. In another example, the holder 1014 may be a surface to which the proximal end of the catheter may be secured (e.g. using an adhesive). In this manner, when a proximal end of a catheter is held in the holder 1014, a position of the catheter is fixed relative to the second section 1008. Thus, sliding the second section 1008 relative to the first section 1002 causes the catheter to move relative to the first section 1002.

[0129] The handpiece 1000 further includes a third section 1016. The third section 1016 is formed of a generally cylindrical hollow body 1018 which is telescopically mounted on the second section 1008, such that the third section 1016 is longitudinally slidable over a length of the second section 1008. A coaxial connector 1020 is mounted on a proximal end 1019 of the body 1018. A proximal end 1022 of the coaxial connector 1020 is exposed on an outside of the body 1018 of the third section 1016. The proximal end 1022 of the coaxial connector 1020 is connectable to an electrosurgical generator, e.g. via a connecting cable (not shown).

[0130] A distal end 1024 of the coaxial connector 1020 is disposed inside the hollow body 1018 of the third section 1016. The distal end 1024 of the coaxial connector 1020 is arranged to receive the proximal end of a coaxial cable of an electrosurgical device. For example, the distal end 1024 of the coaxial connector 1020 may include an inner conductor and an outer conductor which can, respectively, be electrically connected to a centre conductor and an outer conductor of the coaxial cable (e.g. via soldered or welded connections). Alternatively, the distal end 1024 of the coaxial connector 1020 may be adapted to mate with a corresponding connector on the proximal end of the coaxial cable. The coaxial connector 1020 is arranged to convey electromagnetic energy from a cable connected to its proximal end 1022 to a coaxial cable connected to its distal end 1024.

[0131] A slidable limiter 1026 is mounted on an outer surface of the body 1010 of the second section 1008. The slidable limiter 1026 is slidable along the outer surface of the body 1010 of the second section 1008. The position of the slidable limiter 1026 can be fixed relative to the second section 1008 via a fixing screw 1028 which is engaged in a threaded hole in the slidable limiter. The slidable limiter 1026 includes a stopping surface 1030 which is arranged to abut against a distal surface 1029 of the body 1018 of the third section 1016 when the third section is moved in the distal direction (i.e. towards the first section 1002), to prevent further motion of the third section 1016 in the distal direction. In this manner, a range of motion of the third section 1016 relative to the second section 1008 may be adjusted by adjusting the position of the slidable limiter 1026 on the second section 1008.

[0132] In the examples shown in FIGS. 10 and 11, a proximal end of an electrosurgical instrument 1031 is mounted in the handpiece 1000. The electrosurgical instrument may be an electrosurgical instrument according to an embodiment of the invention, e.g. as described above. A proximal end of a catheter 1032 of the instrument 1031 is held in the holder 1014 in the second section 1016 of the handpiece 1000. A proximal end of a coaxial cable 1034 of the instrument 1031 is electrically connected to the distal end 1024 of the coaxial connector 1020 in the third section 1016 of the handpiece 1000. The coaxial cable 1034 is disposed in the catheter 1032 and is slidable along the catheter 1032. The electrosurgical instrument 1031 extends within the hollow bodies of the first, second and third sections of the handpiece 1000. A distal portion of the electrosurgical instrument 1031 exits from the handpiece through the connector 1006 at the distal end of the first section 1002.

[0133] A reinforcing tube 1036 is provided around an outer surface of a proximal portion of the coaxial cable 1034. The reinforcing tube 1036 is secured to the coaxial connector 1020. The reinforcing tube 1036 is made of a rigid material, e.g. a rigid metal or plastic. The reinforcing tube 1036 serves to increase the longitudinal rigidity of proximal portion of the coaxial cable 1034, to facilitate transmission of longitudinal force to the coaxial cable 1034 when the third section 1016 is moved relative to the second section 1008. A proximal portion 1038 of the catheter 1032 has an expanded diameter to enable the proximal portion of the coaxial cable 1034 and the reinforcing tube 1036 to slide within the catheter 1032.

[0134] In use, the distal portion of the electrosurgical instrument 1031 that exits from the connector 1006 may be inserted into the instrument channel of a surgical scoping device. Then, the connector 1006 of the handpiece 1000 may be connected to a corresponding connector on an input port of the surgical scoping device to secure the handpiece 1000 to the surgical scoping device. Subsequently, a length of the catheter 1032 in the instrument channel may be adjusted by sliding the second section 1008 relative to the first section 1002. As the catheter 1032 is fixed relative to the second section 1008 (via the holder 1014), moving the second section 1008 relative to the first section 1002 changes the length of the catheter 1032 which exits from the connector 1006, and hence the length of the catheter 1032 located in the instrument channel. A set of markers 1040 is provided on an outer surface of the body 1004 of the first section 1002. Each marker of the set of markers 1040 indicates a length of the catheter exiting from the handpiece when a distal surface 1041 of the second section 1008 is aligned with that marker. Thus, the second section 1008 may be moved along the first section 1002 to a marker on the first section 1002 corresponding to a desired length of the catheter 1032 in the instrument channel. When the desired length is obtained, the position of the second section 1008 may be fixed relative to the first section 1002, by tightening the fixing screw 1012.

[0135] After adjusting the length of the catheter 1032, the coaxial cable 1034 may be moved along the catheter 1032, e.g. to expose or retract the radiating tip portion of the instrument 1031. The coaxial cable 1034 may be moved along the catheter 1032 by sliding the third section 1016 relative to the second section 1008. Longitudinal motion of the third section 1016 relative to the second section 1008 is transmitted to the distal end of the coaxial cable 1034 which is connected to the coaxial connector 1020 in the third section 1016. The reinforcing tube 1036 prevents the proximal end of the coaxial cable 1034 from bending, so that longitudinal motion of the third section 1016 is transmitted to the coaxial cable 1034. When the third section 1016 is moved in a proximal direction relative to the second section 1008, the reinforcing tube slides into the expanded proximal portion 1038 of the catheter 1032.

[0136] As the catheter 1032 is fixed relative to the second section 1008, sliding the third section 1016 relative to the second section 1008 causes the coaxial cable 1034 to slide within the catheter 1032. Thus, when the handpiece 1000 is used with an electrosurgical instrument of the invention (e.g. electrosurgical instrument 200), the electrosurgical device may be moved between the retracted and deployed positions by moving the third section 1016 backwards and forwards relative to the second section 1008. Specifically, the electrosurgical device may be moved to the deployed position by moving the third section 1016 in a proximal direction relative to the second section 1008, and the electrosurgical device may be moved to the retracted position by moving the third section 1016 in a distal direction relative to the second section 1008.

[0137] A user may adjust the position of the slidable limiter 1026 on the second section 1008 to set a maximum forward position of the third section 1016 relative to the second section 1008. This may set a maximum extension of the radiating tip portion beyond the distal end of the catheter 1032 when the electrosurgical device is in the deployed position. In this manner, the slidable limiter 1026 may prevent the radiating tip portion from being pushed too far beyond the distal end of the catheter 1032. A set of markers 1042 is provided on an outer surface of the body 1010 of the second section 1008. Each marker of the set of markers 1042 indicates a maximum extension of the radiating tip portion beyond the distal end of the catheter 1032 when the slidable limiter 1026 is aligned with that marker and the distal surface 1029 of the third section 1016 abuts against the stopping surface 1030 of the slidable limiter 1026. The slidable limiter 1026 may be thus be moved to a corresponding marker of the set of markers 1042 to set a desired maximum extension of the radiating tip portion.

[0138] FIGS. 13a and 13b illustrate an operation of the handpiece 1000 to move an electrosurgical device of instrument 1031 between a retracted position and a deployed position. In FIG. 13a, the electrosurgical device of instrument 1031 is in a retracted position, i.e. a radiating tip portion of the electrosurgical device does not protrude beyond a distal end 1044 of the catheter 1032. In FIG. 13b, the electrosurgical device of instrument 1031 is in a deployed position, i.e. a radiating tip portion 1046 of the electrosurgical device protrudes beyond the distal end 1044 of the catheter 1032. In this configuration, electromagnetic energy may be delivered to the radiating tip portion 1046 via the coaxial connector 1020 to deliver the energy into target tissue.

[0139] To go from the configuration shown in FIG. 13a to that shown in FIG. 13b, first, the limiter 1026 may be moved to a desired position on the body 1010 of the second section 1008. Then, the third section 1016 may be slid over the second section 1008 in the distal direction. The third section 1016 may be advanced until the distal surface 1029 of the third section 1016 abuts against the slidable limiter 1026, as shown in FIG. 13b. Once treatment of the target tissue has been completed, the radiating tip portion 1046 may be withdrawn back into the catheter 1032 by sliding the third section 1016 in the proximal direction relative to the second section, to return to the configuration shown in FIG. 13a. For illustration purposes, a length of the instrument 1031 is omitted from FIGS. 13a and 13b, as indicated by dashed lines 1048.

[0140] FIG. 14a shows cross-sectional view of a catheter 1400 that may be used as part of an electrosurgical instrument of the invention. The catheter 1400 defines a lumen 1402 extending therethrough and in which an electrosurgical device is receivable. The catheter 1400 includes a proximal section 1404 having a first diameter 1406 and a distal section 1408 having a second, smaller, diameter 1410. Example dimensions for the first and second diameters are 2.70 mm and 2.30 mm, respectively. A stepped section 1412 links the proximal section 1404 and the distal section 1408. The larger diameter of the proximal section 1404 is arranged so that the proximal section 1404 can receive a proximal section of a coaxial cable of an electrosurgical device which includes a reinforcing element (which increases an effective outer diameter of the proximal section of the coaxial cable).

[0141] FIG. 14b shows a cross-sectional view of another catheter 1414 that may be used as part of an electrosurgical instrument of the invention. The catheter 1414 defines a lumen 1416 extending therethrough and in which an electrosurgical device is receivable. The catheter 1414 includes a proximal section 1418 having a first diameter 1420 and an intermediate section 1422 having a second, smaller, diameter 1424. The larger diameter of the proximal section 1404 is arranged so that the proximal section 1404 can receive a proximal section of a coaxial cable of an electrosurgical device which includes a reinforcing element. The proximal section 1418 and intermediate section 1422 are joined by a stepped section 1426.

[0142] A tapered section 1428 is located at a distal end of the catheter 1414. The tapered section 1428 serves to reduce a diameter of the catheter 1414 at the distal end of the catheter from the second diameter 1424 to a third, smaller, diameter 1430. The tapered section 1428 defines a distal opening 1432 of the catheter 1414, a diameter of the distal opening 1432 being the third diameter 1430. The third diameter 1432 is set so that it is larger than an outer diameter of a radiating tip portion of the electrosurgical instrument, and smaller than an outer diameter of a coaxial cable of the instrument. In this manner, the radiating tip portion may protrude through the distal opening 1432 (e.g. when the electrosurgical device is in a deployed position), but the coaxial cable (which has a larger outer diameter than the radiating tip portion) may be prevented from passing through the distal opening 1432. In this manner, the tapered section 1428 may fulfil a similar function to the plug 222 at the end of catheter 204. By providing a tapered section 1428 at the distal end of the catheter 1414, it may thus not be necessary to provide a plug at the distal end of the catheter 1414. This may simplify construction of the electrosurgical instrument. Example dimensions for the first, second and third diameters are 2.70 mm, 2.30 mm and 1.10 mm respectively.

[0143] The different sections of catheters 1400 and 1414 may be made by bonding tubes of different diameters together. Alternatively, catheters 1400 and 1414 may be made from a single tube that is formed by a multi-diameter extrusion process. This may be done by extruding a tube at a first diameter, and then post processing a portion of the tube to remould that portion to a different (e.g. larger) diameter.