Electrosurgical instrument
First Claim
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1. An electrosurgical system for the vaporisation of tissue in the presence of an electrically-conductive medium, the system comprising an electrosurgical generator for generating radio frequency power, and an electrosurgical instrument connectible to the generator, wherein:
- the generator has a radio frequency output stage for delivering radio frequency power to a pair of output connections, which output stage has an open loop output impedance of less than 250 ohms;
the electrosurgical instrument comprises an instrument shaft and, situated at a distal end of the shaft, an electrode assembly comprising an active electrode with an exposed treatment portion and a return electrode with an exposed fluid contact surface, the fluid contact surface being set back from the treatment portion so that, when the electrode assembly is brought into an operative position with the treatment portion on or adjacent to the surface of the tissue to be treated, the fluid contact surface is further from the tissue surface than the treatment portion; and
the ratio of the surface area of the exposed treatment portion to the surface area of the exposed fluid contact surface is greater than or equal to 0.5 to 1;
the electrode assembly further comprising means associated with the active electrode for hindering the dissipation of heat from the active electrode to its surroundings, thereby to encourage the formation and maintenance of a layer of vapour over its surface.
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Accused Products
Abstract
An electrosurgical instrument is disclosed for the treatment of tissue in the presence of an electrically-conductive fluid. The instrument comprises an instrument shaft, and a tissue treatment electrode at one end of the shaft, the tissue treatment electrode being constructed to define thermal barriers for limiting thermal conduction therealong, thereby to encourage the formation and maintenance of a layer of vapor over the electrode.
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Citations
20 Claims
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1. An electrosurgical system for the vaporisation of tissue in the presence of an electrically-conductive medium, the system comprising an electrosurgical generator for generating radio frequency power, and an electrosurgical instrument connectible to the generator, wherein:
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the generator has a radio frequency output stage for delivering radio frequency power to a pair of output connections, which output stage has an open loop output impedance of less than 250 ohms; the electrosurgical instrument comprises an instrument shaft and, situated at a distal end of the shaft, an electrode assembly comprising an active electrode with an exposed treatment portion and a return electrode with an exposed fluid contact surface, the fluid contact surface being set back from the treatment portion so that, when the electrode assembly is brought into an operative position with the treatment portion on or adjacent to the surface of the tissue to be treated, the fluid contact surface is further from the tissue surface than the treatment portion; and the ratio of the surface area of the exposed treatment portion to the surface area of the exposed fluid contact surface is greater than or equal to 0.5 to 1; the electrode assembly further comprising means associated with the active electrode for hindering the dissipation of heat from the active electrode to its surroundings, thereby to encourage the formation and maintenance of a layer of vapour over its surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An electrosurgical instrument for the treatment of tissue in the presence of an electrically-conductive fluid medium, the instrument comprising an instrument shaft and an electrode assembly at a distal end of the shaft, wherein the electrode assembly comprises:
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a single active electrode having an exposed tissue treatment portion; a return electrode having an exposed fluid contact surface; and an insulating member positioned between and electrically insulating the active electrode and the return electrode, and serving to space apart the exposed treatment portion of the active electrode and the exposed fluid contact surface of the return electrode, the fluid contact surface of the return electrode being set back in the direction of a treatment axis of the assembly from the active electrode exposed treatment portion; and wherein the ratio of the area of the exposed treatment portion to the area of the exposed fluid contact surface is greater than or equal to 0.5 to 1; and the active electrode is constituted by a singled coiled filament which defines a generally tubular member, adjacent turns of the coiled filament defining indentations in said generally tubular member, said indentations constituting thermal barriers for limiting thermal conduction along said generally tubular member, whereby, in use, application of sufficient radio frequency power to the electrode assembly vaporises the conductive fluid medium adjacent to the tissue treatment portion to create a stable vapour pocket around the tissue treatment portion.
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20. An electrosurgical instrument for the treatment of tissue in the presence of an electrically-conductive fluid medium, the instrument comprising an instrument shaft and an electrode assembly at a distal end of the shaft, wherein the electrode assembly comprises:
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a single active electrode having an exposed tissue treatment portion; a return electrode having an exposed fluid contact surface; and an insulating member positioned between and electrically insulating the active electrode and the return electrode, and serving to space apart the exposed treatment portion of the active electrode and the exposed fluid contact surface of the return electrode, the fluid contact surface of the return electrode being set back in the direction of a treatment axis of the assembly from the active electrode exposed treatment portion; and wherein the ratio of the area of the exposed treatment portion, to the area of the exposed fluid contact surface is greater than or equal to 0.5 to 1; and the active electrode is configured to define thermal barriers for limiting thermal conduction therealong, whereby, in use, application of sufficient radio frequency power to the electrode assembly vaporises the conductive fluid medium adjacent to the tissue treatment portion to create a stable vapour pocket around the tissue treatment portion.
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Specification