Electrode assembly for an electrosurical instrument

An electrode assembly for the electrosurgical removal of tissue immersed in a electrically conductive liquid, wherein the assembly comprises at least first and second electrodes mounted on a insulator, and at least a pair of conductor wires forming an elongate support structure for housing in an endoscope, the combination of the electrodes and the insulator being secured to distal ends of the wires with one wire of the pair fixedly connected to the first electrode and the other wire of the pair fixedly connected to the second electrode, and wherein the electrodes comprise transversely extending metallic coverings mounted on oppositely directed surfaces of the insulator, the first electrode being mounted on a downwardly directed surface of the insulator and the second electrode being mounted on an upwardly directed surface of the insulator.

A method of electrosurgically removing tissue, comprising:

• providing an electrode assembly having an elongate support structure which includes a pair of conductors and, mounted on a distal end of the support structure, a transversely extending insulator with a tissue treatment electrode secured on a lower face of the insulator and a return electrode secured on an oppositely directed upper face of the insulator, the electrodes being fixedly connected to respective conductors of the said pair, immersing the tissue to be treated in an electrically conductive liquid, bringing the electrode assembly to a location adjacent the tissue to be treated with the electrodes immersed in the conductive liquid, applying an electrosurgical radio frequency voltage between the electrodes of a sufficient magnitude to cause vaporisation of the conductive liquid at the tissue treatment electrode, applying the tissue treatment electrode to the surface of the tissue to be treated with the electrode assembly oriented such that the return electrode is directed away from the tissue surface, and reciprocating the electrode assembly generally in the lengthwise direction of the support structure to ablate the tissue by vaporisation thereof when contacted by the vapour layer over the tissue treatment electrode.

An electrode assembly for the electrosurgical removal of tissue immersed in an electrically conductive liquid, the assembly comprising an elongate support structure including a pair of conductor arms for carrying radio frequency electrosurgical currents, said conductor arms lying substantially in a common plane, an electrically insulative body mounted at a distal end of the support structure and extending transversely with respect to the support structure;

• a transversely extending conductive tissue treatment electrode secured to one side of the insulative body and electrically connected and fixedly secured to a first one of the conductor arms, and a transversely extending conductive return electrode secured to an opposite side of the insulative body and electrically connected and fixedly secured to a second one of the conductor arms, said insulative body, tissue treatment electrode, and return electrode, when secured together, forming a sandwich-like structure having an orientation that is substantially parallel to the plane in which the conductor arms lie.