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Abstract

An electrosurgery system for electrosurgically cutting or vaporising living tissue includes an electrosurgical generator having a pair of output terminals coupled to an electrosurgical instrument containing an electrode assembly. The electrode asssembly has at least one treatment electrode and an adjacent return electrode. The generator and the assembly are arranged to deliver to the treatment and return electrodes radio frequency (r.f.) energy individually or simultaneously at at least two frequencies, one of which is below 100 MHz and the other of which is above 300 MHz. The generator includes a load-responsive control circuit which, in one mode, causes power to be generated predominantly at the lower frequency when the load impedance is high and predominantly at the upper frequency when it is low. This allows automatic switching between cutting and coagulation operation. In another embodiment the r.f. current delivered at the lower frequency is limited in order to restrict dissipation of power in the tissue at that frequency and to permit tissue cutting or vaporisation using energy delivered simultaneously at the higher frequency. In yet another embodiment, the instrument includes a gas plasma generator operating such that an ionisable gas is energised in a gas supply passage by the upper frequency component to form a plasma stream which acts as a conductor for delivering the lower frequency component to a tissue treatment outlet of the passage.

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First Claim