Abstract: An electrosurgical high frequency (HF) generator comprising a generator circuit that produces an HF current between an active electrode and at least one neutral electrode. During the cutting or coagulating of biological tissue, unwanted tissue heating due to the HF current can be reduced because the electrosurgical HF generator comprises at least one further auxiliary neutral electrode connected in parallel to the neutral electrode.

Abstract: In surgery using monopolar HF (high frequency), there is a constant risk of patients suffering burns at the neutral electrode. The problem stems from the fact that numerous methods have been devised by which relatively high HF currents are applied for extended periods of time. The present disclosure solves said problem by providing a neutral electrode device to be used for applying an HF current to a biological tissue. The improved neutral electrode device comprises at least one latent heat accumulator for absorbing heat. Thus, heat peaks can be at least temporarily accumulated until the accumulated thermal energy can be safely released.

Abstract: A device to visually indicate the presence of electric fields in electrosurgical apparatus, without the necessity of wiring or an electrical connection to the apparatus, to visually annunciate when an electrosurgical instrument is active is disclosed. This is to alert the operating surgeon, and observing personnel, that the device is operational to mitigate the possibility of anyone inadvertently being injured. The device is comprised of an electrically insulated enclosure filled with a gas in close proximity to a surgical handpiece connected to a radio frequency current generator.

Abstract: The invention relates to a high frequency surgical device for generating high frequency energy for cutting and/or coagulating biological tissues, comprising at least one resonance circuit with at least two switches, through which an electrical connection between the resonance circuit and an electrical energy source can be switched respectively during operation, in order to supply electrical energy to the resonance circuit during operation at least for periods of time, and with at least one control device associated with the switches through which control device the switches can be switched independently from another.

Abstract: An electrosurgical apparatus for cutting and/or coagulating living tissue, a method of forming the electrosurgical apparatus, and a method of using the electrosurgical apparatus. The cutting and/or coagulating living tissue is performed with one or two heated loops of resistance wire accompanied by sufficient electrical current across the living tissue to enable said cutting and/or coagulating to be performed. The electrosurgical apparatus may include: a glow blade having one or two glow loops of resistance wire; a radio frequency (RF) generator; and one or two voltage supplies configured to operate concurrently, while the one or two glow loops are heated to said glow, to supply both sufficient RF power and associated electrical current across the living tissue for cutting and/or coagulating the living tissue by the one or two glow loops. A first output of the RF generator is electrically coupled to the one or two glow loops.

Abstract: An electrosurgical generator is disclosed. The generator includes an output stage configured to generate a waveform, a first input configured to adjust a cut setting representative of a cutting effect of the waveform, and a second input configured to adjust a hemostasis setting representative of a hemostasis effect of the waveform. The generator also includes a controller configured to receive cut and hemostasis settings and to adjust one of a duty cycle, a crest factor and a power level of the waveform to achieve a combined cutting and hemostasis effect based on the cut and hemostasis settings.

Abstract: A surgical instrument has a first grasping member, a second grasping member which is provided to the first grasping member to open and close to the first grasping member, and grasps a living tissue between them, an ultrasonic coagulation-cutting unit which includes an ultrasonic vibrating portion provided in one of the first and second grasping members and connected to an ultrasonic transducer to generate ultrasonic vibration, and a pressing portion provided in the other of the first and second grasping members, and facing the ultrasonic vibrating portion, the pressing portion and the ultrasonic vibrating portion pressing the living tissue between them, and a high-frequency coagulation unit which includes a first electrode provided in the first grasping member, and a second electrode provided in the second grasping member, the first electrode and the second electrodes facing each other to coagulate the living tissue.

Abstract: In an electro-surgical high-frequency generator, the signal frequency or the modulation frequency or a clock frequency or any combination thereof are modulated using a low-frequency modulation signal in such a way that the spectra thereof are widened. This results in a reduction of interference on peripheral devices.

Abstract: A surgical apparatus for coagulating and cutting tissue includes a handle assembly and a tool cartridge. The tool cartridge includes electrically conductive movable tools, such as jaws and a blade, for cutting tissue. The jaws and blade each are connected to a transmission to facilitate movement. Multiple sheaths are used to encompass and protect the transmissions. Slidable grips are disposed outside of the sheaths and operatively connected to the transmissions that are disposed within the sheaths. At least one lever is supported by the handle assembly and engagable with the grips to facilitate movement of the grips, and thus, the tools.

Abstract: High-strength microwave antenna assemblies and methods of use are described herein. The microwave antenna has a radiating portion connected by a feedline to a power generating source, e.g., a generator. The antenna is a dipole antenna with the distal end of the radiating portion being tapered and terminating at a tip to allow for direct insertion into tissue. The antenna can be used individually or in combination with multiple antennas to create a combined ablation field. When multiple antennas are used, microwave energy can be applied simultaneously to all the antennas or sequentially between the antennas. Furthermore, to facilitate positioning the antennas in or near the tissue to be treated, RF energy may be applied at the tip of the antenna to assist in cutting through the tissue.

Abstract: Apparatus and methods for reducing nerve stimulation in electrosurgical instruments utilizing electrically isolated pairs of electrodes are disclosed. At least two pairs of electrodes may be configured to create at least two opposing currents which effectively cancel one another such that a net current flow is inhibited from developing within surrounding tissue structures to mitigate or eliminate undesired electrical stimulation of the tissue.

Abstract: An electrosurgical controller with wave-shaping. At least some embodiments are methods including generating an alternating current (AC) voltage signal within an electrosurgical controller. The generating may be by inducing an intermediate AC voltage signal on a secondary winding of a first transformer, and wave-shaping the intermediate AC voltage signal by a second winding of a second transformer coupled to the first transformer, and thereby creating a final AC voltage signal. Thereafter, the method includes applying the final AC voltage signal to electrical pins of a connector configured to couple to an electrosurgical wand.

Abstract: Systems, devices, and methods for electrosurgery wherein a circuit bridge is created for a monopolar electrosurgical circuit that provides a matched impedance to load condition thereby joining the active (working) and return (reference) electrode leads into a single bipolar mode device.

Abstract: A patient is provided with an increased sense of satiety by increasing resistance to the outflow of food from the stomach and through the intestines. Stomach emptying may be slowed with devices implantable within the gastrointestinal tract below the stomach. Implants are preferably removable and can include artificial strictures or apertures that may be adjustable or elastic to vary the rate of stomach emptying. Slowing gastric emptying may induce satiety for a longer period and may therefore reduce food consumption. Many of the embodiments include intestinal sleeves or sleeves, but they need not. The resistor concept may be applied to a simple anchor and resistor without a long sleeve.

Abstract: An ultrasonic treatment device comprises a transducer unit, probe unit, and a main unit. The transducer unit comprises an ultrasonic transducer generating ultrasonic vibration in response to supply of power. The probe unit has a treatment member at a distal end thereof. The probe unit is detachably loaded to the transducer unit, and is equipped with an ultrasonic probe transmitting the ultrasonic vibration to the distal end of the treatment member when the transducer unit is loaded to the probe unit. The main unit is manually grasped by an operator. The probe unit with the transducer unit loaded thereto is detachably loaded to the main unit. The main unit has a cylindrical insert through which the ultrasonic probe is inserted to have the treatment member protruded outwardly when the probe unit is loaded. The main unit further has an outer sheath detachably covering an outer surface of the insert.

Abstract: An electrosurgical controller with output RF energy control. At least some of the illustrative embodiments are electrosurgical controllers configured to change a first output voltage on the first active terminal relative to the first return terminal by selective control of a number of turns of the primary winding of a transformer used to create the output voltage.

Abstract: A combination tissue removal and cauterization instrument includes one or more heads configured to remove tissue by mechanical cutting action resulting from rotation, vibration and/or other type of powered motion. The heads also have electroconductive outer surfaces to which electrical energy is supplied, thereby permitting the heads to simultaneously cauterize tissue that is not removed.

Abstract: This invention relates to a method of straddling an intraosseous nerve with an energy transmitting device to improve the therapeutic treatment of the nerve.

Abstract: A high-frequency power supply device and an electrosurgical device are provided which can automatically control the output of an appropriate high-frequency current in accordance with the condition of a biological tissue to be treated. A phase detection unit detects respective phases of a high-frequency voltage and a high-frequency current outputted in a high-frequency power generation unit, and thereafter a phase difference calculation unit calculates the phase difference based on the respective phases. Meanwhile, an impedance calculation unit calculates the impedance on the basis of respective magnitudes of the high-frequency voltage and the high-frequency current. In this case, on the basis of at least one of the impedance and the phase difference and the output state of an instruction signal, a control unit performs a control to output a high-frequency voltage and a high-frequency current having a predetermined waveform.

Abstract: An electrosurgical device is provided which can prevent the decrease of the effect of a treatment performed by an operator or the like on a biological tissue. A high-frequency voltage generated in an alternating power supply is transformed in a transformer. A high-frequency current in accordance with the transformed high-frequency voltage is supplied to the biological tissue via two high-frequency current supply lines. In this case, the impedance between the two high-frequency current supply lines is set in an impedance matching circuit so as to become maximum with respect to the frequency of the high-frequency current. Accordingly, the decrease of the effect of the treatment performed on the biological tissue can be prevented.

Abstract: An electrosurgical instrument for use by a surgeon that provides additional features and benefits compared with known designs. The operating mode as well as other operating parameters, especially power level, can be preset by the surgeon before commencing the procedure. Five operating modes are available using a three-button fingerswitch handpiece and a 3-way footswitch, including three unipolar modes and two bipolar modes over a full range of power levels including a new turbo mode for treating heavy bleeders.

Abstract: A surgical instrument, such as an endoscopic or laparoscopic instrument, includes an ablation device. The ablation device includes an elongate flexible member having a proximal end and a distal end. A first working channel is formed within the flexible member. A first diagnostic probe having a proximal end and distal end is located within the first working channel and extends through the distal end of the flexible member. A first electrode is connected to the distal end of the first diagnostic probe electrode is adapted to be endoscopically located in a tissue treatment region. The first electrode is adapted to couple to an electrical waveform generator to receive an irreversible electroporation electrical waveform sufficient to ablate tissue located proximate to the first electrode. A system further includes an electrical waveform generator electrically coupled to the first electrode of the ablation device to generate an IRE waveform sufficient to ablate tissue located proximate to the first electrode.

Abstract: The electrosurgical instrument is configured to selectively perform ablation or coagulation as desired. The electrosurgical instrument includes at least two electrodes on the electrode probe that can be activated using an RF generator. The electrosurgical instrument is selectively switchable between an ablation mode and a coagulation mode by changing the amount of active surface area. In particular, in the ablation mode, a relatively small surface area is active. Thus, for a given power input, the current density is relatively high. In the coagulation mode, the active surface area is increased, thereby reducing the current density in the coagulation mode for the given power input.

Abstract: The invention concerns a high frequency generator for the connection of an electrosurgical instrument comprising an electrical output terminal for an electrosurgical instrument, a current or voltage source connected at least indirectly to the output terminal, an arc detector, and a power control for controlling the electrical power delivered by way of the output terminal, wherein the power control is adapted firstly to cause the delivery of a high output power for a phase for the initial cutting support and subsequently thereto either if ignition of an arc has occurred during the phase for initial cutting support for a predetermined period of time of a cutting phase to cause the delivery of a power which is reduced in relation to the high power and subsequently for a predetermined period of time of a long pause interval to cause the delivery of no power or a lower power at which no arc occurs, or if no ignition of an arc has occurred during the phase for initial cutting support to cause the delivery of no pow

Abstract: An electrosurgical electrode capable of vaporization, coagulation, desiccation or cutting of tissue is disclosed. The probe has a first portion configured for tissue vaporization, and a second portion configured for tissue desiccation or coagulation. Simultaneous vaporization and desiccation may be achieved, the balance between the effects being controlled by the orientation and motions of the electrode. The electrode may have irrigation and aspiration means.

Abstract: An electrosurgical system includes an electrosurgical generator including at least one source of radio frequency (RF) power, and a plurality of output connections, only one of the output connections at any one time being active in that it is able to receive radio frequency power from the source. The generator includes selection means adapted to change the active output connection, and a controller adapted to control the supply of radio frequency power from the source to the active output connection. The system also includes a plurality of electrosurgical assemblies, each including an electrosurgical instrument and a cable connecting the electrosurgical instrument to one of the output connections. The electrosurgical assemblies each include a handswitch adapted to send a signal to the selection means to change the active output connection.

Abstract: Surgical instruments are arranged for cutting and cauterizing tissue with a closed-loop wire. An extension/retraction mechanism forces a closed wire loop to constrict upon tissue enclosed by the loop as the loop is retracted and drawn to a smaller size. Simultaneously, as electrical current is passed through the wire loop and further into the tissue, the tissue is resected and cauterized. The closed wire loop is electrically coupled to a remote power source via conductor(s) which cooperate with the extension/retraction mechanisms. The extension/retraction mechanism permits the loop to be extended and retracted as it is adjusted from a first limit position towards a second limit position and respectively back again. Further, the entire instrument is devised to function in cooperation with common laparoscopic port systems.

Abstract: A surgical apparatus for coagulating and cutting tissue includes a handle assembly and a tool cartridge. The tool cartridge includes electrically conductive movable tools, such as jaws and a blade, for cutting tissue. The jaws and blade each are connected to a transmission to facilitate movement. Multiple sheaths are used to encompass and protect the transmissions. Slidable grips are disposed outside of the sheaths and operatively connected to the transmissions that are disposed within the sheaths. At least one lever is supported by the handle assembly and engagable with the grips to facilitate movement of the grips, and thus, the tools.

Abstract: An ultrasonic clamp coagulator assembly that is configured to permit selective cutting, coagulation and clamping of tissue during surgical procedures. An elongated portion of the instrument can be configured for endoscopic applications and has an outside diameter of less than 6 mm. The construction includes a clamping mechanism, including a clamp arm pivotally mounted at the distal portion of the instrument, which is specifically configured to create a desired level of tissue clamping forces, exceeding 4 pounds when the trigger is fully closed. The clamping mechanism includes a two-piece pad design and pad material that enables the higher tissue clamping forces and a force-limiting mechanism that effectively smooths out abusive tissue forces. The assembly also features hand activation configured to provide an ergonomical grip and operation for the surgeon. Hand switches are placed in the range of the natural swing of the surgeon's thumb, whether gripping the surgical instrument right-handed or left handed.

Abstract: The surgical tool comprises a longitudinally extending waveguide (1) defining a longitudinal axis (2). A first jaw member (1b) is connected at a distal end of the waveguide (1). A longitudinally extending carrier tube (3) is rotatable about the waveguide (1) and a second jaw member (6) is pivotably mounted to a distal end of the carrier tube (3). An outer shroud (7) includes a guide lobe (9) bearing on a rearward face of the second jaw member. Rotation of the carrier tube (3) causes pivoting of the second jaw member (6) into and out of operative relationship with the first jaw member (1b).

Abstract: The invention relates to an electrosurgical instrument (5) for an endoscope or a catheter, which can be operated by means of a high-frequency current, contact electrosurgical treatment and non-contact plasma coagulation in an ionisable gas. A stationary electrode (33) is arranged on the distal end of a guiding tube (7) that can be introduced into the instrument channel (1) of an endoscope catheter (3), and when the electrosurgical electrode for the contact treatment is in the retracted position in the guiding tube (7), the stationary electrode is connected to the electrosurgical electrode (11) by means of a contact element (37).The retracted position of the electrode (11) can, but not necessarily, be maintained by an abutment (21) of a handling device (13) and/or by a suitable arrangement and measurement of the contact element (37). The retracted position of the electrode (11) does not need to be optically controlled.

Abstract: An electrosurgical generator is disclosed, which includes an RF output stage connected to a DC power supply and first and second connections. The first connection includes a first switching component and a first parallel inductor-capacitor resonant circuit. The second connection includes a second switching components and a second parallel inductor-capacitor resonant circuit. The first and second switching components are configured to open and close at a predetermined frequency based on a phase-correlated dual drive signal emitted by a driver and are in a 180 degree out-of-phase relationship. The first parallel inductor-capacitor resonant circuit is further configured to produce a first half-sinusoidal waveform and the second parallel inductor-capacitor resonant circuit is configured to produce a second half-sin half-sinusoidal waveform.

Abstract: An electrosurgical pencil is provided and includes an elongated housing having an electrocautery blade supported therein and extending distally from the housing. The electrocautery blade is connected to a source of electrosurgical energy. The pencil further includes a plurality of activation switches supported on the housing for activating electrocautery blade. Each activation switch is configured and adapted to selectively complete a control loop extending from the source of electrosurgical energy upon actuation thereof. In use, actuation of at least one of the plurality of activation switches produces a dividing with hemostatic effect at the electrocautery blade. The electrosurgical pencil further includes at least one voltage divider network supported on the housing. The at least one voltage divider network is electrically connected to the source of electrosurgical energy and controls the intensity of electrosurgical energy being delivered to the electrosurgical pencil.

Abstract: An electrosurgical electrode for use in a surgical procedure includes an elongated body in the shape of a Freer elevator having a working end portion in the shape of a spoon at a distal end thereof. The working end portion is an active electrosurgical end capable of supplying electrosurgical currents when the electrode is operatively connected to an electrosurgical apparatus and the later is activated. An opposite proximal end of the body includes a means, such as a connector, for operatively connecting the electrode to the electrosurgical apparatus for supplying the electrosurgical currents to the working end portion.

Abstract: An electrosurgical instrument that is capable of generating high-quality RF energy carriers at one of three different frequencies and combining any of the three carriers with any one of four electrosurgical mode waveform modulations and selectively supplying the modulated carriers to either a monopolar or a bipolar handpiece. In a preferred embodiment, the first carrier frequency is in the range of about 3.8-4.0 MHz, the second carrier frequency is in the range of about 1.7-2.0 MHz, and the third carrier frequency is in the range of about 400-600 KHz.

Abstract: Electrosurgical tissue specimen recovery apparatus and system employing a multi-leaf capture component configured with pursing cables which are electrosurgically excited to define a cutting leading edge. To complete a capture, the cables are loaded in tension to purse and thus converge the tips of the capture component leafs together. The forward regions of the leafs are configured with a combination of a thin flat stainless steel region over which a polymeric cable guide is positioned. The polymeric cable guide and stainless steel leaf driving combination improves frictional aspects as well as the resulting aspect ratio of a recovered tissue specimen.

Abstract: A treatment device to treat a living tissue includes a sealing member which joints desired regions of at least two living tissues to each other in a sealed state, and a maintaining member which maintains contact between the tissues located in the vicinity of parts jointed by the sealing member.

Abstract: An electrosurgical system includes a generator for generating radio frequency power, and an electrosurgical instrument including at least three electrodes and. The generator includes a radio frequency output stage having at least a pair of RF output lines, and a power supply coupled to the output stage for supplying power to the output stage. A controller is operable to limit the radio frequency output voltage developed across the output lines to at least a first predetermined threshold value to produce a cutting RF waveform, and a second threshold value to produce a coagulating RF waveform. In a combined mode, the controller delivers both cutting and coagulating waveforms, either simultaneously or by alternating constantly between the first and second threshold values to form a blended signal.

Abstract: An intelligent selection system for operating an electrosurgical instrument for use by a surgeon that depends primarily on the surgical procedure to be employed. The operating mode as well as other operating parameters can be controlled by the handpiece chosen by the surgeon to perform the procedure. Each handpiece is customized to activate when operated one of several preset operating modes of the electrosurgical instrument.

Abstract: The invention relates to a HF surgical instrument for treating, in particular, for cutting and coagulating biological tissue by means of a HF current. The HF surgical instrument comprises a HF generator for supplying a HF current to a cutting electrode and comprises at least one control device for interrupting a HF current circuit. The design of this HF surgical instrument is improved in that a cutting capacity is enhanced. In addition, the control device comprises a current monitoring device that detects the amplitude of the HF current and then generates a first switch-off signal when the HF current decreases over a defined period of time and/or the HF current falls below a threshold value characterizing a state of the treated tissue. The control device also comprises an electric arc monitoring device, which then generates a second switch-off signal when an electric arc occurs between the cutting electrode and the tissue.

Abstract: A surgical instrument, such as an endoscopic or laparoscopic instrument, includes an ablation device. The ablation device includes an elongate relatively flexible member having a proximal end and a distal end, the flexible member includes at least a first working channel. A first and second electrode extends from a working channel at the distal end of the flexible member. The first and second electrodes are adapted to be endoscopically located in a tissue treatment region. The first and second electrodes are adapted to couple to an electrical waveform generator to receive an irreversible electroporation electrical waveform sufficient to ablate tissue located between the first and second electrodes.

Abstract: An apparatus comprises an ultrasonic transducer, a probe portion, the proximal end being coupled to the ultrasonic transducer, ultrasonic waves output from the ultrasonic transducer being transmitted to the probe portion, a storage portion which stores the ultrasonic transducer, a cylindrical casing portion which has a distal end and a proximal end and which is installed outside the storage portion, an electric path provided to extend between an electric contact disposed at the distal end of the casing portion and an electric cable connecting portion provided at the proximal end of the casing portion, and an electric cable which has a distal end and a proximal end, the proximal end being connected to a power supply unit, the distal end being coupled to the electric cable connecting portion, the electric path being disposed between the storage portion and the casing.

Abstract: A cautery tool is provided with a compact, lightweight, user-directable lighting facility that can be powered by either a shared external power source from which a power flow is shared continuously with the cautery function, by a supplemental self-contained power cell that may be recharged by a portion of the external power for use independently of the cautery function, or by sharing of a self-contained power cell by the cautery and the lighting functions. Waste heat generated during exercise of the lighting function is continuously removed from a light-emitting element by electrical conductors also serving as heat transfer conduits.

Abstract: Electrosurgery method and apparatus. In the method, tissue is cut or coagulated, with an electrically low conductive liquid providing cooling. In another method, skin is cut by electrosurgery in a dry field using a low duty cycle signal energizing the cutting electrode, minimizing tissue charring. A combination coagulation and cutting electrode performs both functions. The cutting is performed by a blade edge generating a local plasma adapted for cutting. Superimposed on the blade edge is an electrode of greater surface area electrically insulated from the cutting electrode, for coagulation. In another version, a single component cutting/coagulation blade (electrode) has a cutting and a flat partially insulated portion defining through holes in the insulation for coagulation. Also provided is an electrical circuit whereby each electrode is isolated by a filter from cross talk and feedback of the RF signal from the other electrode, minimizing arcing.

Abstract: A surgical instrument has a first grasping member, a second grasping member which is provided to the first grasping member to open and close to the first grasping member, and grasps a living tissue between them, an ultrasonic coagulation-cutting unit which includes an ultrasonic vibrating portion provided in one of the first and second grasping members and connected to an ultrasonic transducer to generate ultrasonic vibration, and a pressing portion provided in the other of the first and second grasping members, and facing the ultrasonic vibrating portion, the pressing portion and the ultrasonic vibrating portion pressing the living tissue between them, and a high-frequency coagulation unit which includes a first electrode provided in the first grasping member, and a second electrode provided in the second grasping member, the first electrode and the second electrodes facing each other to coagulate the living tissue.

Abstract: The present invention provides systems, apparatus and methods for selectively applying electrical energy to body tissue in order to ablate, contract, coagulate, or otherwise modify a target tissue or organ. The closed configuration is adapted for clamping and coagulating a target tissue while the apparatus is operating in the sub-ablation mode, while the open configuration is adapted for ablating the target tissue via molecular dissociation of tissue components. A method of the present invention comprises clamping a target tissue or organ with an electrosurgical probe. A first high frequency voltage is applied between the active electrode and the return electrode to effect coagulation of the clamped tissue. Thereafter, a second high frequency voltage is applied to effect localized molecular dissociation of the coagulated tissue.

Abstract: The invention features compact apparatuses useful in electrosurgery.

Abstract: A tissue ablation probe comprises an elongated probe shaft, at least one fluid perfusion lumen longitudinally extending through the probe shaft, and a plurality of electrodes carried by the distal end of the probe shaft. Each of the electrodes includes a porous structure in fluid communication with the at least one perfusion lumen. The electrodes have a substantially co-extensive surface.

Abstract: In an electrosurgical generator for generating radio frequency power, the generator comprises a radio frequency output stage having three or more output connections, one or more sources of output power coupled to the output stage, and a controller operable to cause the generator to supply a first cutting RF waveform to the output connections or a second coagulating RF waveform to the output connections. In a combined mode, the controller causes the generator to deliver both first and second RF waveforms, the controller including means for feeding the waveforms to the output connections such that the first RF waveform is delivered between a first pair of the output connections, and the second RF waveform is delivered between a second pair of the output connections. The combined mode is adjustable between various settings, each setting having a different proportion of the first and second RF waveforms.

Abstract: An electrosurgical generator has output terminals for connection to active and return electrodes respectively of an electrosurgical instrument and, connected to the output terminals via at least one isolation capacitor, a radio frequency (r.f.) source which may be pulsed by a pulsing circuit. To permit tissue removal at a high rate, the source and the pulsing circuit are arranged so as to generate a pulsed r.f. output signal having a peak-to-peak voltage of at least 1250V, a mark-to-space ratio not more than 1:1, and a pulse length not more than 100 ?s.