An elongate structure, a bipolar electrosurgical device, and an electrosurgical system

Abstract

Various embodiments provide an elongate structure for delivery of bipolar energy. The elongate structure is for use in an electrosurgical device. The elongate structure comprises: one or more insulator strands; a first conductive strand configured to provide an elongate first electrode; and, a second conductive strand configured to provide an elongate second electrode. The first conductive strand is electrically isolated from the second conductive strand by the one or more insulator strands. The first electrode and second electrode are configured to deliver bipolar energy into biological tissue. Some other embodiments provide a bipolar electrosurgical device comprising the elongate structure, and an electrosurgical system comprising the bipolar electrosurgical device.

Description

[0001] An Elongate Structure, A Bipolar Electrosurglcal Device, and

[0002] An Electrosurglcal System

[0003] Field of the Invention

[0004] The present invention relates to an elongate structure for a bipolar electrosurglcal device, and a bipolar electrosurgical device having the elongate structure. The elongate structure includes two conductive strands which provide two electrodes for delivering bipolar energy into biological tissue. Also, the elongate structure includes one or more insulator strands which isolate the two conductive strands from each other. In a specific embodiment, the elongate structure is a rope.

[0005] Background

[0006] The invention relates to a bipolar electrosurgical device, e.g. an electrosurgical snare device for use in a polypectomy procedure, or an electrosurgical sphincterotome. In particular, the invention may relate to medical snares and sphincterotomes suitable for insertion down the instrument channel of an endoscope (or any other type of scoping device used in the gastrointestinal (Gl) tract or elsewhere in the human or animal body, such as the nasal cavity), and which may include a means for introducing electromagnetic energy into biological tissue.

[0007] Polyps in the Gl tract can be removed using a medical snare in an endoscopic procedure, e.g. using a colonoscope. In the case of pedunculated polyps, the snare is passed over the polyp and tightened around the polyp’s neck (or stem), which is then cut and the polyp removed. The cutting process may be performed or enhanced by passing a radiofrequency (RF) or microwave energy through the biological tissue. The energy may also facilitate cauterisation.

[0008] Some existing pseudo-bipolar snares comprise a first electrode located on the snare wire, and a second electrode provided as a cap at the end of a probe that the snare loop extends from. However, improvements on such arrangements are desired. In particular, the probe is typically used during a stage of inspecting of the human or animal body without the cap provided thereon, and thus, in order to make use of the pseudo-bipolar capabilities of such snares following inspection, it is necessary to remove the probe from the human or animal body, fit the cap, and subsequently re-insert the probe into the human or animal body.

[0009] Improvements in the structures for delivery of bipolar energy in electrosurgical sphincterotomes is also desired.

[0010] The present invention has been devised in light of the above considerations.

[0011] 008717373Summary of the Invention

[0012] In a first aspect there is provided an elongate structure for delivery of bipolar energy, the elongate structure for use in an electrosurgical device, the elongate structure comprising: one or more insulator strands; a first conductive strand configured to provide an elongate first electrode; and a second conductive strand configured to provide an elongate second electrode; and wherein the first conductive strand is electrically isolated (or insulated) from the second conductive strand by the one or more insulator strands, such that the first electrode and second electrode are configured to deliver bipolar energy into biological tissue.

[0013] The structure according to the first aspect is simple to manufacture, can provide a spacing (e.g. constant spacing) between the first and second electrodes along the length of the elongate structure, and allows for delivery of bipolar energy with a reduced risk of a short circuit (e.g. arcing) between the first and second electrodes

[0014] In an embodiment, the first conductive strand is electrically isolated from the second conductive strand by the one or more insulator strands, such that a spacing is maintained between the first electrode and second electrode along the length (e.g. entire length) of the elongate structure to avoid a short circuit. The first and / or second electrode may be provided along a length of the elongate structure (e.g. the first conductive strand and / or second conductive strand may be exposed on an outer surface of the elongate structure along a length of the elongate structure. In some embodiments, the length along which the first and / or second electrode is provided is spaced from a first end and / or a second end of the elongate structure. In some embodiments, the length along which the first electrode and / or second electrode is provided corresponds to a majority, or (substantially) all, of the length of the elongate structure.

[0015] The bipolar signal may be a radiofrequency (RF) electromagnetic (EM) signal, such that the RF EM energy can be delivered to tissue e.g. tissue contacting the first and / or second electrodes. In this way, the first electrode provided by the first conductive strand may be the active electrode, and the second electrode provided by the second conductive strand may be the return electrode, or vice versa. In use, the electromagnetic energy may be used to ablate or coagulate tissue that is in contact with the elongate structure and / or to assist in a cutting operation.

[0016] The first electrode and second electrode may be isolated (e.g. insulated) from each other by the insulator strands being interposed therebetween, and having no electrically conductive material extending between the first electrode and the second electrode.

[0017] In some embodiments, one or more of the insulator strands comprises an electrically conductive core and an insulating sheath (or insulating jacket, or insulating cladding) surrounding the electrically conductive core. The electrically conductive core may also assist with heat dissipation, as electrically conductive materials typically also provide high heat conductivity. In other examples, the insulator strands may consist of insulating material, e.g. being a homogenous strand of insulating material. In this way, manufacture of the insulator strands may be made simpler compared to sheathing an electrically conductive core, and the breakdown voltage of the elongate structure may be increased. The insulating

[0018] 008900573sheath or insulating material may comprise enamel, silicon, silicon-based paint, ceramic, polymer, perfluoroalkoxy alkanes, and / or diamond. Advantageously, such materials are electrically insulating and biocompatible. The insulating sheath or insulating material may comprise enamel (e.g. the insulating sheath or material may be formed of enamel). The enamel sheath and / or enamel material may have a thickness of less than or equal to 1.0 mm. The enamel sheath and / or enamel material may have a thickness of greater than or equal to 0.02 mm. Preferably, the enamel sheath and / or enamel material has a thickness between 0.3 mm and 0.1 mm, e.g. about 0.2 mm. The enamel may have a breakdown electric field strength between 170 V / pm and 220 V / pm. The electrically conductive core of the insulator strand, where present, may comprise stainless steel, tin, silver, gold and / or nitinol. Nitinol is a shape memory alloy, and therefore it may be possible to re-shape the elongate structure comprising a nitinol-containing insulator strand.

[0019] The first conductive strand and / or the second conductive strand may comprise, or consist of, a conductive wire (e.g. a metal wire). The first and second conductive strands may be exposed on an outer surface of the elongate structure. In this way, the electrodes can be brought into contact with the biological tissue that bipolar energy is to be delivered to. The first electrode and second electrode may be exposed on an outer surface of the elongate structure along its length (e.g. along a major portion, or all, of its length). That is, the first conductive strand and second conductive strand may be unsheathed along their length (e.g. along a major portion, or all, of its length). In this way, delivery of bipolar energy into biological tissue along the length of the elongate structure, as opposed to at a single position, can be facilitated. The delivery of energy / radiation to tissue from the electrodes may be via conduction, for example, the electrodes may contact the tissue to conduct bipolar energy (e.g. bipolar radio frequency (RF) energy) to the tissue.

[0020] The first conductive strand and / or the second conductive strand may comprise stainless steel, tin, silver, gold and / or nitinol. Advantageously, such materials are highly conductive and biocompatible. Nitinol is a shape memory alloy, and therefore it may be possible to re-shape the elongate structure comprising a nitinol-containing conductive strand.

[0021] The conductive strands may extend along the elongate (e.g. length) dimension of the elongate structure, e.g. between a first end and a second end of the elongate structure. The insulator strands may extend along the elongate dimension of the elongate structure, e.g. between a first end and a second end of the elongate structure.

[0022] The one or more insulator strands may provide a first recess in which the first conductive strand may be located / received. Similarly, the one or more insulator strands may provide a second recess in which the second conductive strand may be located / received. In this way, the position of the first conductive strand and / or second conductive strand in the elongate structure may be supported by the one or more insulator strands. In this way, the likelihood of the first conductive strand coming into electrical contact with the second conductive strand can be reduced. The recesses may be diametrically opposed from each other on the elongate structure.

[0023] 008900573In some embodiments, the elongate structure comprises a plurality of insulator strands. This may improve the flexibility of the elongate structure compared to a single insulator strand having substantially the same shape and size as the combined plurality of insulator strands.

[0024] The elongate structure may be a rope. That is, the conductive and insulator strands of the elongate structure may be twisted, wound, and / or braided together. The elongate structure can thus be used to deliver bipolar energy around its outer surface at different circumferential positions, because both the first conductive strand and second conductive strand wrap around the elongate structure between different circumferential positions. The rope may be a helically wound rope. This provides a simple manner in which to manufacture the elongate structure such that the conductive strands and insulator strands are held together and can provide a flexible and strong elongate structure. The helically wound rope may have a 1x7 structure. That is, the rope may comprise 7 strands, with 6 outer strands being helically wound around a central strand. The central strand and four outer strands may be insulator strands. This can provide reliable electrical insulation between the first conductive strand and second conductive strand, even during movement and bending of the elongate structure.

[0025] The first conductive strand and second conductive strand may be provided on diametrically opposite sides of the elongate structure. In this way, the likelihood of a direct electrical connection and / or shorting between the first conductive strand and second conductive strand is reduced, since the conductive strands are maximally spaced from each other within the elongate structure. Where the elongate structure is a rope, e.g. a helically wound rope, it can be appreciated that the position of the first and second conductive strands on the outer surface of the elongate structure changes along the length of the elongate structure, but that at any given point along the length of the elongate structure, the first conductive strand may be diametrically opposed to the second conductive strand (e.g. in a plane substantially perpendicular to the elongate dimension of the elongate structure).

[0026] One or more of the first conductive strand, the second conductive strand, and the one or more insulating strands may be circular in cross section (e.g. in a plane substantially perpendicular to the elongate dimension of the elongate structure). The strands having a circular cross section may provide the elongate structure with improved flexibility by a reduction in the friction between strands compared to other cross-sectional shapes.

[0027] The elongate structure may have a diameter greater than or equal to 0.25 mm. The elongate structure may have a diameter less than or equal to 1.0 mm, e.g. greater than or equal to 0.4 mm and less than or equal to 1.0 mm. Preferably, the diameter of the elongate structure is about 0.6 mm. In this way, the elongate structure can be made very flexible. Additionally, such a diameter can provide suitable spacing between the first conductive strand and second conductive strand such that the risk of direct electrical contact and / or shorting between the first conductive strand and second conductive strand is low or negligible, whilst still allowing for effective transfer of bipolar energy into the biological tissue such that both cutting and coagulation of the biological tissue are possible. Distances less than 0.25 mm, e.g. 0.1 mm, may increase the likelihood of electrical breakdown in air between adjacent electrodes. Distances greater than 1.0 mm may reduce the ease of forming a conductive path through the biological tissue between adjacent electrodes. The diameter of the elongate structure may be defined as the diameter of 008900573the circle circumscribing the cross section of the elongate structure in a plane substantially perpendicular to the elongate dimension of the elongate structure.

[0028] One or more of the first conductive strand, the second conductive strand, and the one or more insulator strands may have a diameter greater than or equal to 0.1 mm. One or more of the first conductive strand, the second conductive strand, and the one or more insulator strands may have a diameter less than or equal to 0.3 mm, e.g. greater than or equal to 0.1 mm and less than or equal to 0.3 mm. Preferably, the diameter of one or more of the first conductive strand, the second conductive strand, and the one or more insulator strands is about 0.2 mm. In this way, the elongate structure can be made very flexible and the resistance of the first conductive strand and second conductive may be kept low. The diameter of a strand may be defined as the diameter of the circle circumscribing the cross section of the rope in a plane substantially perpendicular to an elongate dimension of the strand.

[0029] The first electrode may be configured as an active electrode and the second electrode may be configured as return electrode for delivering bipolar energy (e.g. RF EM energy) corresponding to the bipolar signal (e.g. an RF signal) into the biological tissue (e.g. via conduction). In this way, bipolar energy may be delivered from the elongate structure to the surrounding tissue.

[0030] In second aspect, there is provided a bipolar electrosurgical device comprising an elongate structure according to the first aspect.

[0031] Any one or more of the optional features set out with respect to the first aspect are equally applicable to, and are hereby restated in respect of, the second aspect, except where clearly impermissible or expressly avoided.

[0032] The bipolar electrosurgical device may comprise: a sleeve; and a transmission line for conveying a bipolar signal, the transmission line extending through the sleeve; and wherein: the elongate structure extends from the sleeve; and the first and second conductive strands are coupled to the transmission line for receipt of the bipolar signal therefrom, such that the first electrode and second electrodes are configured to deliver bipolar energy corresponding to the bipolar signal into biological tissue. In this way, the bipolar electrosurgical device can be configured for the delivery of bipolar energy.

[0033] The transmission line may comprise a first conductor electrically connected (directly or indirectly) to the first conductive strand and a second conductor electrically connected (directly or indirectly) to the second conductive strand. This arrangement can allow for delivery of electromagnetic energy (e.g. a bipolar electromagnetic signal) to the elongate structure via the transmission line. The transmission line can be connected (e.g. at its proximal end) to a suitable electrosurgical generator to receive bipolar energy (e.g. RF EM energy). The two conductors may be electrically isolated from each other. In some embodiments, the transmission line may comprise a twisted pair. In other embodiments, the transmission line may comprise a coaxial cable, i.e. having an inner conductor, an outer conductor surrounding and coaxial with the inner conductor, and a dielectric material separating the inner conductor from the outer conductor. The bipolar electrosurgical device may further comprise a handle / interface joint. The handle / interface joint may be located at a proximal end of the sleeve. The handle / interface joint may comprise an actuation mechanism for driving the actuator. The handle / interface joint may comprise an energy port 008900573(e.g. a radiofrequency (RF) electromagnetic (EM) energy port). The handle / interface joint may provide a junction between an interface cable (e.g. a cable for delivery of RF EM energy from a generator to the energy port) connected to the handle / interface joint and the transmission line of the bipolar electrosurgical device. The handle / interface joint described in WO 2019 / 073037may be used.

[0034] The sleeve may be arranged to enclose the transmission line, control rod, transformer portion and parts of the bipolar electrosurgical device other than at least a portion of the elongate structure. The sleeve may have an internal longitudinal partition which separates an internal volume of the sleeve into a first lumen for carrying the transmission line and a second lumen for carrying a control rod that is connected to the elongate structure. The control rod (otherwise known as a control wire, actuation wire, actuation rod, or push rod) may be a tube or sheath mounted around the transmission line and slidable relative to it. The sleeve may be electrically insulative. The sleeve being electrically insulative may be understood as meaning that the sleeve is formed from an electrically insulative material. By way of example, the insulative sleeve may be formed from a material selected from a group consisting of: polytetrafluoroethylene; silicone; polyvinylchloride; and polypropylene. A first end of the elongate structure may extend into the first lumen of the sleeve, and a second end of the elongate structure may extend into the second lumen of the sleeve; in this way, the internal longitudinal partition can prevent the portions of the electrodes at the first end of the elongate structure contacting the electrodes at the second end of the elongate structure.

[0035] The bipolar electrosurgical device of the second aspect may be configured for insertion down an instrument channel of a surgical scoping device, e.g. an endoscope, gastro scope, bronchoscope, etc., or may be arranged for use in laparoscopic surgery or in natural orifice translumenal endoscopic surgery (NOTES), transanal endoscopic microsurgery (TEMS), or trans-anal submucosal endoscopic resection (TASER) procedures or in a general open procedure. The diameter of the instrument channel in the endoscope may be 2.2 mm, 2.8 mm, 3.2 mm or larger. The maximum width of the structures discussed herein may thus be set to be lower than one or more of these dimensions.

[0036] The sleeve may be flexible. This can aid with inserting the electrosurgical device into a patient and positioning the device as required for the electrosurgical operation.

[0037] In one embodiment, the bipolar electrosurgical device may be a snare device or surgical snare device. A retractable loop for ensnaring an area containing biological tissue is formed at least in part by the elongate structure, the elongate structure being movable relative to the sleeve for retraction of the retractable loop. An axial position of the elongate structure may be fixed relative to the transmission line and / or the handle / interface joint and the retractable loop may be retractable by movement of the sleeve relative to the elongate structure and transmission line and / or the handle / interface joint; for example, the actuator may be configured to move the sleeve. Alternatively, an axial position of the sleeve may be fixed relative to the transmission line and / or the handle / interface joint and the retractable loop may be retractable by movement of the elongate structure relative to the sleeve and transmission line and / or the handle / interface joint; for example, the actuator may be configured to move the elongate structure e.g. by movement of the control rod to which at least one end of the elongate structure is connected, as

[0038] 008900573discussed above. Either arrangement may provide a simple mechanism for retraction and extension of the retractable loop from the sleeve.

[0039] In an embodiment, the bipolar electrosurgical snare device also provides a cold cut capability in which tissue ensnared by the retractable loop can be mechanically cut by retracting (i.e. tightening) the retractable loop around tissue until that tissue is cut off or removed from surrounding tissue. That is, the cut may not be performed or enhanced by bipolar energy, such as, RF energy. The elongate structure and / or sleeve may be structurally modified in order to enhance this mechanical cutting capability, for example, by including one or more sections which are sharpened to form a blade or blade-type structure to improve cutting of ensnared tissue. As such, the bipolar electrosurgical snare may be a hybrid device (or hybrid snare) capable of selectively cutting via mechanical means and / or using bipolar energy (such as RF energy).

[0040] The first and second electrodes may be configured to deliver bipolar energy corresponding to the bipolar signal into biological tissue that is in the area ensnared by the retractable loop and / or may be configured to deliver bipolar energy corresponding to the bipolar signal into bipolar tissue outside said area.

[0041] The elongate structure may form a closed loop (that is, the elongate structure may extend around the entire circumference of the retractable loop), e.g. the elongate structure may comprise a first end that is (directly) connected to a second end of the elongate structure to form the loop. Alternatively, the retractable loop may be formed by a combination of the elongate structure and a distal end (e.g. a distal end surface) of the sleeve (e.g. the elongate structure may comprise a first end that is not directly connected to a second end of the elongate structure); for example, even with the elongate structure in a fully extended position from the distal end of the sleeve, the retractable loop may be formed by a combination of the elongate structure and the distal end of the sleeve.

[0042] The bipolar electrosurgical snare device may further comprise an actuator configured to actuate the retractable loop from a retracted state to an extended state and vice versa. The actuator may act to move the elongate structure relative to the sleeve. In this way, the snare device can cut tissue by applying a mechanical force to tissue ensnared therein, in addition to, or alternatively to, by applying electromagnetic energy to the tissue. The actuator may include a gearing system, e.g. having a ratio of 2:1 or 3:1 , to give the operator fine control over the retraction and extension of the loop. A rack and pinion type arrangement may be suitable for the gearing mechanism.

[0043] A first end of the elongate structure may be connected to the control rod that is axially slidable relative to the distal end of the sleeve, and a second end of the elongate structure may be attached such that is it axially fixed relative to the distal end of the sleeve. Movement of the first end relative to the distal end of the sleeve causes the retractable loop to extend and retract. Alternatively, the second end may also be axially slidable relative to the distal end of the sleeve (i.e. the first and second ends are both axially slidable relative to the distal end of the sleeve). By way of example, the first and second ends may be movable simultaneously with respect to the distal end of the sleeve e.g. by the second end also being connected to the control rod. In this way, alignment of the loop (e.g. such that the same portion of the elongate structure is the distalmost point of the retractable loop regardless of whether the retractable loop

[0044] 008900573is in a retracted or an extended state) may be maintained, and moreover, the length of the device can be shortened, since the control rod only needs to traverse half the distance along the transmission line to achieve the same change in the size of the loop as an arrangement in which only one end of the elongate structure is attached to the control rod. In these ways, the control rod can provide the actuator of the bipolar electrosurgical snare device.

[0045] In the retracted state, the retractable loop may have a diameter of between 5 mm and 0.5 mm. In this manner, the device can be used to “spot” coagulate the area around a polyp stalk to stem blood flow before beginning a polypectomy procedure. The device may be used in this retracted configuration to coagulate vessels in the bowel or around an area where the polyp stalk is to be removed. Alternatively or additionally, the device may be used in the retracted configuration to mark out a region around a sessile polyp or tumour. Post procedure, the user may apply energy using the snare in the retracted configuration to coagulate / thermally destroy tissue.

[0046] An axial position of the elongate structure may be fixed relative to the transmission line and / or the handle / interface joint and the retractable loop may be retractable by movement of the sleeve relative to the elongate structure and transmission line and / or the handle / interface joint; for example, the actuator may be configured to move the sleeve. Alternatively, an axial position of the sleeve may be fixed relative to the transmission line and / or the handle / interface joint and the retractable loop may be retractable by movement of the elongate structure relative to the sleeve and transmission line and / or the handle / interface joint; for example, the actuator may be configured to move the elongate structure e.g. by movement of the control rod to which at least one end of the elongate structure is connected, as discussed above. Either arrangement may provide a simple mechanism for retraction and extension of the retractable loop from the sleeve.

[0047] In another embodiment, the bipolar electrosurgical device may be a sphincterotome. The sphincterotome may comprise a cutting wire extending from the sleeve at a position spaced from a distal end of the sleeve. The cutting wire may be formed at least in part by the elongate structure, the cutting wire (e.g. the elongate structure) being movable relative to a portion of the sleeve for deflection of the distal end of the sleeve. Typically, the cutting wire is fixed / attached to the distal end portion of the sleeve, and the portion of the sleeve that the elongate structure is movable relative to is the remainder of the sleeve (i.e. the whole of the sleeve except the distal end portion). The distal end portion of the sleeve may have a rest position relative to the remainder of the sleeve, which the distal end portion of the sleeve adopts absent an external force on the distal end of the sleeve, and deflection of the distal end portion of the sleeve may comprise moving the distal end of the sleeve out of the rest position by application of an external force (e.g. by the cutting wire exerting a bending moment on the sleeve).

[0048] The cutting wire may extend from inside the sleeve to outside the sleeve through an aperture in the sleeve. The aperture may be at a position spaced from the distal end of the sleeve. The aperture may be a through-hole in a sidewall of the sleeve.

[0049] The bipolar electrosurgical sphincterotome device may further comprise an actuator configured to deflect the distal end of the sleeve by movement of the elongate structure relative to the portion of the sleeve. In

[0050] 008900573this way, the sphincterotome device can cut tissue by applying a mechanical force to tissue ensnared therein, in addition to, or alternatively to, by applying electromagnetic energy to the tissue. The actuator may include a gearing system, e.g. having a ratio of 2:1 or 3:1 , to give the operator fine control over the deflection of the tip. A rack and pinion type arrangement may be suitable for the gearing mechanism. The sphincterotome may comprise a control rod (otherwise known as a control wire, actuation wire, actuation rod, or push rod) attached to a proximal end of the cutting wire. The control rod may be the same structure as, or a different structure to, the transmission line. A first (e.g. proximal) end of the cutting wire may be attached to the control rod. A second (e.g. distal) end of the cutting wire may be attached to the distal end portion of the sleeve. The control rod may be movable relative to the sleeve for deflection of the distal end portion of the sleeve, e.g. movement of the control rod in a proximal direction relative to the sleeve may deflect the distal end portion of the sleeve. The cutting wire and elongate structure may be movable in an axial direction relative to all of the sleeve apart from the distal end portion of the sleeve where the second end of the cutting wire is attached to the sleeve.

[0051] The control rod may be slidable relative to the sleeve. In this way, the control rod provides an actuator that is able to actuate a distal portion of the sphincterotome by changing the length of the portion of cutting wire extending outside the sleeve between the aperture and the distal end. Actuation of the control rod to move it in a proximal direction (i.e. in a direction away from the distal end of the sleeve) results in the distal portion of the sleeve (i.e. between the aperture and distal end) bowing to form an arc and the distal end deflecting. The exposed portion of the cutting wire (i.e. that extending outside the sleeve) may form a secant of the arc, so as to facilitate a transection procedure with the sphincterotome.

[0052] In a third aspect there is provided a method of manufacturing the elongate structure according to the first aspect or the bipolar electrosurgical device according to the second aspect.

[0053] Any one or more of the optional features set out with respect to the first aspect and / or second aspect are equally applicable to, and are hereby restated in respect of, the third aspect, except where clearly impermissible or expressly avoided.

[0054] The method may comprise winding the first conductive strand, the second conductive strand, and the one or more insulating strands together.

[0055] The method may comprise connecting the elongate structure to the control rod and / or the sleeve.

[0056] In a fourth aspect, there is provided an electrosurgical system comprising a bipolar electrosurgical device according to the second aspect and an electrosurgical generator for generating bipolar energy.

[0057] Any one or more of the optional features set out with respect to the first aspect, second aspect, and / or third aspect are equally applicable to, and are hereby restated in respect of, the fourth aspect, except where clearly impermissible or expressly avoided.

[0058] The electrosurgical generator may comprise a first terminal and a second terminal, the first conductive strand (and first electrode) may be electrically connected to the first terminal and the second conductive strand (and second electrode) may be electrically connected to the second terminal. The first terminal may be a positive terminal and the second terminal may be a negative terminal, or vice versa.

[0059] 008900573Alternatively, the first terminal may be a positive terminal and the second terminal may be an earth terminal, or vice versa. Alternatively, the first terminal may be a negative terminal and the second terminal may be an earth terminal, or vice versa.

[0060] The electrosurgical generator may be any device capable of delivery RF EM energy (and optionally microwave frequency EM energy) for treatment of biological tissue. For example, the generator described in WO 2012 / 076844 may be used.

[0061] Where the bipolar electrosurgical device comprises a handle / interface joint, the system may further comprise an interface cable configured for connecting the generator to the handle. In this way, the bipolar signal can be delivered from the generator to the device. The handle / interface joint may provide the junction between the interface cable and the transmission line of the device.

[0062] Herein, an electrosurgical device may be any device which in use is arranged to use RF EM energy and / or microwave frequency EM energy for the treatment of biological tissue. The electrosurgical device may use the RF EM energy and / or microwave frequency EM energy for any or all of resection, coagulation and ablation.

[0063] Herein, “microwave energy” may be used broadly to indicate an electromagnetic energy in a frequency range of 400 MHz to 100 GHz, but preferably in a range of 1 GHz to 60 GHz, more preferably 2.45 GHz to 30 GHz or 5 GHz to 30 GHz. The invention may be used at a single specific frequency, such as any one or more of: 915 MHz, 2.45 GHz, 3.3 GHz, 5.8 GHz, 10 GHz, 14.5 GHz and 24 GHz.

[0064] Herein, radiofrequency (RF) may mean a stable fixed frequency in the range 10 kHz to 300 MHz. The RF energy should have a frequency high enough to prevent the energy from causing nerve stimulation and low enough to prevent the energy from causing tissue blanching or unnecessary thermal margin or damage to the tissue structure. Preferred spot frequencies for the RF energy include any one or more of: 100 kHz, 250 kHz, 400kHz, 500 kHz, 1 MHz, 5 MHz.

[0065] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0066] Summary of the Figures

[0067] Embodiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0068] Figure 1 is a perspective view of a section of an elongate structure for delivery of bipolar energy;

[0069] Figure 2 is a schematic view of an electrosurgical system having a bipolar electrosurgical snare device in the instrument channel thereof;

[0070] Figure 3 is a schematic partial cross-sectional view of the bipolar electrosurgical snare device in Figure 2; and

[0071] Figure 4 is a schematic partial cross-sectional view of a bipolar electrosurgical sphincterotome.

[0072] 008900573Detailed Description of the Invention

[0073] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0074] Figure 1 is a perspective view of a section of an elongate structure 10 that is capable of delivering bipolar energy into biological tissue.

[0075] In Figure 1, the elongate structure 10 is illustrated as a linear structure, however, it can be appreciated that when incorporated into a bipolar electrosurgical device, the elongate structure 10 may be deformed into a non-linear (e.g. curved) shape e.g. such as to form at least part of a retractable loop of a snare device.

[0076] The elongate structure 10 comprises a plurality of strands, including a first conductive strand 1 , a second conductive strand 2, and five insulator strands 3. The elongate structure 10 in Figure 1 is in the form of a rope, where the strands have been wound together into a helical structure. As a result of a combination of the number, shape, size, and configuration of the strands, the plurality of insulator strands 3 electrically insulate the first conductive strand 1 from the second conductive strand 2.

[0077] Specifically, the rope structure in Figure 1 is a 1x7 structure, with the rope comprising a central strand (being one of the insulator strands 2) and six outer strands, the outer strands being four insulator strands 3 and the first and second conductive strands 1 , 2). The first and second conductive strands 1 , 2 are a diametrically opposed pair of outer strands, and are separated by the five insulator strands 2, such that no electrically conductive material extends between the first conductive strand 1 and second conductive strand 2 within the elongate structure 10, such that the conductive strands 1 , 2 are electrically isolated from each other. It can be appreciated that the 1x7 structure results in the insulator strands 3 providing first and second recesses within the elongate structure that the first conductive strand 1 and second conductive strand 2 are located, the recesses being diametrically opposed from each other within the elongate structure 10.

[0078] The first conductive strand 1 and second conductive strand 2 are exposed on the outer surface of the elongate structure 10 along its length, such that the conductive strands 1 , 2 can be brought into contact with the biological tissue that bipolar energy is to be delivered to. In this way, it can be understood that the first and second conductive strands 1 , 2 provide the elongate structure 10 with a first electrode and a second electrode, respectively. Although the first and second conductive strands 1 , 2 wrap around the elongate structure 10 between different circumferential positions, the 1x7 structure of the rope means that the gap between the first and second conductive strands 1 , 2 is constant across the outer surface of the elongate structure 10.

[0079] The strands 1 , 2, 3 of the elongate structure 10 are substantially circular in cross section (i.e. in the cross section shown in Figure 1 that is substantially perpendicular to the elongate dimension L of the elongate structure 10). As illustrated in Figure 1, the insulator strands 3 are sheathed strands, comprising an

[0080] 008900573electrically conductive metal core 3a and an electrically insulating sheath 3b that then means that the insulator strands 3 act to insulate the electrically conductive strands 1 , 2 from each other. In contrast, the first and second conductive strands 1 , 2 are unsheathed conductive metal wires. The strands each have a diameter of about 0.2 mm, and thus the overall diameter D of the elongate structure 10 is about 0.6 mm. The material for the conductive strands 1 , 2 and the conductive metal cores 3a is typically one of stainless steel, tin, silver, gold and nitinol, whilst the insulating sheaths 3b are typically formed of one of enamel, silicon, silicon-based paint, ceramic, polymer, perfluoroalkoxy alkanes, and diamond.

[0081] The bipolar signal is typically a radiofrequency (RF) electromagnetic (EM) signal, such that the RF EM energy can be delivered to tissue e.g. tissue contacting the first and / or second electrodes. In this way, the first electrode provided by the first conductive strand 1 may be the active electrode, and the second electrode provided by the second conductive strand 2 may be the return electrode, or vice versa. In use, the electromagnetic energy may be used to ablate or coagulate tissue that is in contact with the elongate structure and / or to assist in a cutting operation.

[0082] Figure 2 is a schematic diagram of a complete electrosurgery system 100 that is capable of selectively supplying to the distal end of an invasive electrosurgical device, RF energy and / or microwave energy. The system 100 comprises a main body 102 and a flexible shaft 104 extending from the main body, which is suitable for insertion into the body to access the treatment site. The shaft 104 houses various channels, e.g. a surgical device channel and an observation channel (not shown) as is conventional. The observation channel may carry optical equipment suitable for delivering an image of the treatment site to an observation port 106.

[0083] The main body 102 includes a surgical device port 108 for receiving a surgical device (in this case a bipolar electrosurgical snare device) into the instrument channel.

[0084] As explained in more detail below, the bipolar electrosurgical device comprises a flexible sleeve 110 which has at its distal end the elongate structure of Figure 1 , in this case forming a retractable loop 112 of an electrosurgical snare device. The retractable loop 112 is connected to a flexible control rod (not shown in Figure 1) which is conveyed by the sleeve 110. The retractable loop 112 is an active tip for delivering RF EM energy and / or microwave EM energy into biological tissue.

[0085] The system 100 further comprises a generator 105 for controllable supplying electromagnetic (EM) energy. In the present embodiment, the EM energy includes RF EM energy and / or microwave frequency EM energy. A suitable generator for this purpose is described in WO 2012 / 076844, which is incorporated herein by reference.

[0086] The generator 105 is connected to a handle / interface joint 114 of the bipolar electrosurgical snare device by an interface cable 103. A function of the handle / interface joint 114 is to combine the inputs from the generator 105 and a slider (actuation mechanism) 116 into the flexible sleeve 110, which extends from the distal end of the handle / interface joint 114. In this embodiment, an energy port 117 (for receiving EM energy from the generator 105) is angled relative to an outlet to the flexible sleeve 110 and the slider 116 (for driving the actuator) is in-line with the outlet to the flexible sleeve 110. The interface cable 104 is connected to the generator 105 using a QMA-type coaxial interface, which is designed to 008900573allow continuous clockwise or counterclockwise rotation. An assistant supports the interface joint 106 throughout the procedure in order to assist the user with sympathetic instrument rotation.

[0087] The flexible sleeve 110 is insertable through the entire length of the surgical device port 108 of the main unit 102 and the surgical device channel of the flexible shaft 104.

[0088] Alternatively to the snare device in Figure 2, the system 100 may comprise an electrosurgical sphincterotome, wherein a cutting wire of the sphincterotome is formed at least in part by the elongate structure of Figure 1 , as is discussed further below in relation to Figure 4.

[0089] Figure 3 is a schematic partial cross-sectional view of the distal end of the bipolar electrosurgical snare device in Figure 2. As discussed in relation to Figure 2, the snare device comprises a flexible sleeve 110 (e.g. made from nylon) and an inner control rod 111 (e.g. made from stainless steel) that is mounted within and slidable relative to the outer sleeve 110. The elongate structure 10 is connected to a distal end of the control rod 111. In this example, both ends of the elongate structure 10 are connected to the control rod 111. It can be appreciated that the retractable loop 112 of the device in Figure 3 is formed by a distal end surface 115 of the sleeve 110 and the elongate structure 10 of Figure 1. The control rod 111 does not extend beyond the distal end surface 115 of the sleeve 110, and thus, even with the elongate structure 10 in a fully extended position from the sleeve 110, the retractable loop 112 is formed by a combination of the elongate structure 10 and the distal end surface 115 of the sleeve 110, rather than by the elongate structure 10 and the control rod 111. In an alternative configuration, the elongate structure 10 may form a closed loop, with both ends connected together, such that, at least in the fully extended position, the closed loop 112 is defined by just the elongate structure 10.

[0090] By being slidable relative to the outer sleeve 110, the control rod 111 provides an actuator that is able actuate the retractable loop 112 from a retracted state to an extended state and vice versa. Where a distal end of the control rod 111 is proximate the distal end surface 115 of the sleeve 110, the retractable loop 112 is in the extended state, and sliding of the control rod 111 to move the distal end of the control rod 111 away from the distal end surface 115 of the sleeve 110 in the direction of the proximal end of the sleeve 110 causes retraction of the retractable loop 112. Accordingly, in use, biological tissue can be ensnared in the retractable loop 112, with the retractable loop 112 then being capable of retraction around said tissue to reduce the size of the loop and exert a mechanical force on the ensnared biological tissue.

[0091] As illustrated in Figure 3, the control rod 111 is a tube and the bipolar electrosurgical snare device further comprises a transmission line 118 extending through the sleeve 110 and the control rod 111. The transmission line 118 comprises a first conductor 118a and a second conductor 118b, and allows for delivery of bipolar electromagnetic energy to the elongate structure 10 at the distal end of the transmission line 118. Specifically, the first conductor 118a is electrically connected to the first conductive strand 1 of the elongate structure 10, whilst the second conductor 118b is electrically connected to the second conductive strand 2 of the elongate structure 10. The handle 114 in the system of Figure 2 comprises the energy port 117 that provides a junction between the transmission line 118 and the

[0092] 008900573interface cable 103 connected to an electromagnetic (EM) signal generator 105, such that the EM signal can be fed to the transmission line 118 and subsequently delivered to the elongate structure 10.

[0093] In order for the bipolar electrosurgical snare device to be able to deliver bipolar energy to tissue, the elongate structure 10 comprises the first electrodes provided by the first conductive strand 1 that is electrically isolated from the second electrode provided by the second conductive strand 2, the first electrode being configured as an active electrodes and the second electrode being configured as a return electrodes (or vice versa).

[0094] Figure 4 is a schematic partial cross-sectional view of the distal end of a bipolar electrosurgical sphincterotome device. The sphincterotome device comprises a flexible sleeve 210 (e.g. made from nylon) and an inner control rod 211 (e.g. made from stainless steel) that is mounted within and slidable relative to the outer sleeve 210. The sphincterotome further comprises a cutting wire 213 that is formed at least in part by the elongate structure 10 of Figure 1. A first end of the cutting wire 213 is connected to a distal end of the control rod 213, whilst a second end of the cutting wire 213 is connected to a distal end 219 of the flexible sleeve 210. The cutting wire 213 extends from inside the sleeve 210 to outside the sleeve 210 through an aperture 215 in the sleeve 210 at a position spaced from the distal end 219 of the sleeve. The cutting wire 213 and elongate structure 10 are movable in an axial direction relative to all of the sleeve 210 apart from the distal end 219 where the second end of the cutting wire is connected to the sleeve 210.

[0095] By being slidable relative to the sleeve 210, the control rod 211 provides an actuator that is able to actuate a distal portion of the sphincterotome by changing the length of the portion of cutting wire extending outside the sleeve 210 between the aperture 215 and the distal end 219.

[0096] Accordingly, in combination with the sleeve 210 being flexible, movement of the cutting wire 213 and elongate structure 10 (e.g. in an axial direction using the control rod 211 ) can cause deflection of the distal end 219 of the sleeve 210 by flexion of the portion of the sleeve 210 positioned between the aperture 215 and the distal end 219 of the sleeve. Actuation of the control rod 211 to move it in a proximal direction (i.e. in a direction away from the distal end 219 of the sleeve 210) results in the distal portion of the sleeve 210 (i.e. between the aperture 215 and distal end 219) bowing to form an arc (as illustrated in Fig. 4) and the distal end 219 deflecting. The exposed cutting wire 213 forms a secant of the arc, so as to facilitate a transection procedure with the sphincterotome.

[0097] As illustrated in Figure 4, the control rod 211 is a tube and the bipolar electrosurgical sphincterotome device further comprises a transmission line 218 extending through the sleeve 210 and the control rod 211. The transmission line 218 comprises a first conductor 218a and a second conductor 218b, and allows for delivery of bipolar electromagnetic energy to the elongate structure 10 at the distal end of the transmission line 218. Specifically, the first conductor 218a is electrically connected to the first conductive strand 1 of the elongate structure 10, whilst the second conductor 218b is electrically connected to the second conductive strand 2 of the elongate structure 10. The handle 114 in the system of Figure 2 comprises the energy port 117 that provides a junction between the transmission line 218 and the

[0098] 008900573interface cable 103 connected to the electromagnetic (EM) signal generator 105, such that the EM signal can be fed to the transmission line 218 and subsequently delivered to the elongate structure 10.

[0099] In order for the bipolar electrosurgical sphincterotome device to be able to deliver bipolar energy to tissue, the elongate structure 10 comprises the first electrodes provided by the first conductive strand 1 that is electrically isolated from the second electrode provided by the second conductive strand 2, the first electrode being configured as an active electrodes and the second electrode being configured as a return electrodes (or vice versa).

[0100] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0101] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0102] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0103] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0104] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0105] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

[0106] 008900573

Claims

Claims:

1. An elongate structure for delivery of bipolar energy, the elongate structure for use in an electrosurgical device, the elongate structure comprising:one or more insulator strands;a first conductive strand configured to provide an elongate first electrode ; anda second conductive strand configured to provide an elongate second electrode;wherein the first conductive strand is electrically isolated from the second conductive strand by the one or more insulator strands, andwherein the first electrode and second electrode are configured to deliver bipolar energy into biological tissue.

2. The elongate structure according to claim 1 , wherein the one or more insulator strands comprise an electrically conductive core and an insulating sheath surrounding the electrically conductive core.

3. The elongate structure according to claim 2, wherein the insulating sheath comprises enamel, silicon, silicon-based paint, ceramic, polymer, perfluoroalkoxy alkanes, and / or diamond.

4. The elongate structure according to any preceding claim, wherein the first conductive strand and / or the second conductive strand comprises, or consists of, a conductive wire.

5. The elongate structure according to claim 4, wherein the conductive wire comprises stainless steel, tin, silver, gold, and / or nitinol.

6. The elongate structure according to any preceding claim, wherein the elongate structure comprises a plurality of insulator strands.

7. The elongate structure according to any preceding claim, wherein the elongate structure is a rope.

8. The elongate structure according to claim 7, wherein the rope is a helically wound rope, optionally having a 1x7 structure.

9. The elongate structure according to claim 8, wherein a central strand and four outer strands are insulator strands.

10. The elongate structure according to any preceding claim, wherein the first conductive strand and second conductive strand are provided on diametrically opposite sides of the elongate structure.

11. The elongate structure according to any preceding claim, wherein one or more of the first conductive strand, the second conductive strand, and the one or more insulating strands are circular in cross section.00890057312. The elongate structure according to any preceding claim, wherein the diameter of the elongate structure is greater than or equal to 0.4 mm and less than or equal to 1 mm.

13. The elongate structure according to any preceding claim, wherein one or more of the first conductive strand, the second conductive strand and the one or more insulator strands has a diameter greater than or equal to 0.1 mm and less than or equal to 0.3 mm.

14. A bipolar electrosurgical device comprising an elongate structure according to any one of claims 1 to 13.

15. The bipolar electrosurgical device according to claim 14, wherein the bipolar electrosurgical device comprises:a sleeve; anda transmission line for conveying a bipolar signal, the transmission line extending through the sleeve; andwherein:the elongate structure extends from the sleeve; andthe first and second conductive strands are coupled to the transmission line for receipt of the bipolar signal therefrom, such that the first electrode and second electrodes are configured to deliver bipolar energy corresponding to the bipolar signal into biological tissue.

16. The bipolar electrosurgical device according to claim 14 or 15, wherein the bipolar electrosurgical device is a surgical snare.

17. The bipolar electrosurgical device according to claim 16, wherein a retractable loop for ensnaring an area containing biological tissue is formed at least in part by the elongate structure, the elongate structure being movable relative to the sleeve for retraction of the retractable loop.

18. The bipolar electrosurgical device according to claim 17, wherein:an axial position of the elongate structure is fixed relative to the transmission line and the retractable loop is retractable by movement of the sleeve relative to the elongate structure and transmission line; oran axial position of the sleeve is fixed relative to the transmission line and the retractable loop is retractable by movement of the elongate structure relative to the sleeve and transmission line.

19. The bipolar electrosurgical device according to claim 14 or 15, wherein the bipolar electrosurgical device is a sphincterotome.

20. The bipolar electrosurgical device according to claim 19, wherein:008900573the sphincterotome comprises a cutting wire extending from the sleeve at a position spaced from a distal end of the sleeve; andthe cutting wire is formed at least in part by the elongate structure, the cutting wire being movable relative to a portion of the sleeve for deflection of the distal end of the sleeve.

21. The bipolar electrosurgical device according to claim 20, wherein:the sphincterotome comprises a control rod attached to a proximal end of the cutting wire; and the control wire is movable relative to the sleeve for deflection of the distal end of the sleeve.

22. An electrosurgical system comprising:the bipolar electrosurgical device according to any one of claims 13 to 18; andan electrosurgical generator for generating bipolar energy.008900573

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