Abstract: The invention relates to an HF generator and to a method for limiting the output effective power of the HF generator, especially for performing HF surgical cutting and coagulation of human or animal tissue. According to the invention, the output voltage and the HF output current of the HF generator are detected by at least two detector devices, the peak values and the effective values of the HF output voltage and of the output current as well as the mean value of the output effective power of the HF generator are determined by an evaluation device, and the calculated mean value is compared to a defined maximum mean value of the output effective power of the HF generator by a comparison device. Afterwards, a modulation device modulates the HF output voltage using a pulse-shaped modulation signal.

Abstract: Methods for heating tissue completely, thoroughly, and uniformly comprise delivering radio frequency energy through a bipolar surgical instrument having first and second jaws with first and second electrode members within the treatment region. Tissue is grasped between the first and second jaws of the bipolar instrument. The electrode members are energized at a power level to deliver electrical energy to and heat tissue between the first and second electrode members. The power level is increased at a predetermined rate from an initial level. The initial level and predetermined rate are selected to avoid creating a vapor layer and to permit an impedance increase to occur as a result of complete tissue desiccation. A tissue impedance may also be measured and compared to a preset impedance limit for terminating the power delivery when the measured impedance exceeds the impedance limit.

Abstract: The present invention relates, in general, to electrosurgical instruments and, more particularly, to a feedback light used in cooperation with an electrosurgical instrument. The present invention further comprises first and second moveable jaws. A first electrode is housed within the first moveable jaw and a second electrode is housed within the second moveable jaw, where the electrodes are connectable to a power source for providing an electric current between the electrodes. The present invention further comprises a feedback light connectable to a first lead and a second lead in order to form a second circuit, where the second circuit is adjacent to the first circuit in order to facilitate capacitive coupling between the first and second circuits in order to light a feedback light.

Abstract: The electric surgical operation apparatus of the present invention easily and securely shortens the rising time until incision and coagulation effects appear even if electrodes having different volumes or surface areas are used for the treatment tool. Cutting sharpness and safety are improved and the operation time is shortened. In the electric surgical operation apparatus, contact of a monopolar electrode of a monopolar treatment tool with organic tissue is detected by a voltage or current sensor. Based on a detection signal therefrom, a high-frequency output is supplied at a predetermined value from a high-frequency cautery power source device, and a high-frequency output is supplied at a higher initial setting value than the predetermined value during an initial period at a rising time. Setting of at least one of the initial period and the initial setting value can be changed.

Abstract: Disclosed is an electrosurgical generator that comprises a circuit and method to produce a filtering technique that utilizes the output transformer as the inductive element of the filter and places two capacitors on the output of the transformer to produce the desired filtering. The output filter configuration eliminates the use of power inductors and still creates the filtering required in electrosurgical applications. The filter utilizes the inductive properties of the output transformer along with several capacitors to form the bandpass filter.

Abstract: Described is a high-frequency surgical instrument with automatic control of the intensity of the electric arcs between the active electrode and the tissue that is to be cut or coagulated, whereby for determination of the extent of the electric arcs, a therefrom dependent signal (K) is shunted off through a filter and conducted to a rectifier whose output signal is conducted to a variable-gain amplifier in which this output signal is compared either with the set-point signal (S) of a set-point device for the cutting process or with the set-point signal (K) of a set-point device for the coagulation process. The variable-gain amplifier generates a signal proportional to the difference of the signals E minus S or E minus K, respectively, which is conducted to an amplitude modulator which controls the amplitude of the output voltage of the power amplifier.

Abstract: An electrosurgery system includes an electrosurgical generator (10) coupled to or part of an electrosurgical instrument, the generator being operable to generate electrosurgical power in low frequency (typically at 1 MHz) and high frequency bands (typically at 2.45 GHz) either simultaneously or individually the generator includes a load-responsive control circuit which, in one mode, causes power to be generated predominantly at 1 MHz when the load impedance is high and predominantly at 2.45 MHz when it is low. This allows automatic switching between cutting and coagulation operation. In one embodiment, the instrument includes a gas plasma generator operating such that an ionizable gas is energized in a gas supply passage by the 2.45 GHz component to form a plasma stream which acts as a conductor for delivering the 1 MHz component to a tissue treatment outlet of the passage. (FIG. 4).

Abstract: An electrosurgical apparatus supplies high-frequency power from a high-frequency power supply unit to an instrument placed in association with an organic tissue to dissect or coagulate the organic tissue. An impedance calculating section calculates the impedance value of the organic tissue. A rate-of-impedance-change calculating section calculates the rate of impedance change of the organic tissue based on the impedance value calculated by the impedance calculating section. A control section controls the high-frequency output of the high-frequency power supply unit based on a predetermined condition provided by combining the impedance value calculated by the impedance calculating section with the rate of impedance change calculated by the rate-of-impedance-change calculating section.

Abstract: An electrosurgical apparatus comprises a high frequency generator (I) with an associated power control system, a handpiece (2) with means for removably mounting an electrode (5) therein, and a connection cable (3) between an output (4) of the generator and the handpiece. The transfer characteristic of the system provides a substantially true ohmic transfer of loads on the electrode side of the connection cable (3) to the generator side thereof at or around a predetermined load on the electrode.

Abstract: An apparatus and method are provided for control contraction of tissue that includes collagen fibers. The apparatus includes a handpiece, and an electrode with an electrode proximal end associated with the handpiece. A distal end of the electrode has a geometry that delivers a controlled amount of energy to the tissue for a desired contraction of the collagen fibers. This is achieved while dissociation and breakdown of the collagen fibers is minimized. The handpiece, with electrode, is adapted to be introduced through an operating cannula in percutaneous applications. Additionally, an operating cannula may be included in the apparatus and be attached to the handpiece. The apparatus and method provides for a desired level of contraction of collagen soft tissue without dissociation or breakdown of collagen fibers.

Abstract: An electric surgical operation apparatus comprises: an active electrode which performs medical treatment to an area to be treated by applying electric energy to the area; an electric power supplying unit which supplies electric power to the active electrode; a measuring unit which measures at least one of the electrical power output voltage value supplied to the active electrode from the electric power supplying unit, and the output current value thereof; a discerning unit for discerning whether or not the change in at least one of the voltage value and the current value measured by the measuring unit has attained a predetermined change amount; and a voltage control unit for controlling the electric power supplying unit so that the supplied electric power is a constant voltage, according to the discerning results discerned by the discerning unit.

Abstract: An electrosurgical apparatus supplies high-frequency power from a high-frequency power supply unit to an instrument placed in association with an organic tissue to dissect or coagulate the organic tissue. An impedance calculating section calculates the impedance value of the organic tissue. A rate-of-impedance-change calculating section calculates the rate of impedance change of the organic tissue based on the impedance value calculated by the impedance calculating section. A control section controls the high-frequency output of the high-frequency power supply unit based on a predetermined condition provided by combining the impedance value calculated by the impedance calculating section with the rate of impedance change calculated by the rate-of-impedance-change calculating section.

Abstract: An electrosurgical system including an electrode assembly having two electrodes for use immersed in an electrically conductive fluid has a generator with control circuitry for rapidly reducing the delivered radio frequency output power by at least 50% within at most a few cycles of the peak radio frequency output voltage reaching a predetermined threshold limit. In this way, tissue coagulation can be performed in, for example, saline without significant steam generation. The same peak voltage limitation technique is used in a tissue vaporization or cutting mode to limit the size of the steam pocket at the electrodes and to avoid electrode burning. In a blended mode, the output voltage is alternately limited to a value appropriate for coagulation and a value appropriate for cutting or vaporization.

Abstract: A heating treatment system consists mainly of coagulating/incising forceps in which a plurality of heating elements are incorporated, and a main unit that feeds power to the heating elements incorporated in the coagulating/incising forceps and that drives and controls the heating elements. The main unit can be connected to coagulating/incising forceps in which up to four heating elements are incorporated. The main unit includes element temperature measurement/output control units and temperature setting units which are associated with four channels allocated to the heating elements. A control unit controls the element temperature measurement/output control units and temperature setting units. The control unit judges the type of connected forceps by referencing data stored in advance in a memory using information of the type of forceps received from the coagulating/incising forceps, and controls power feed to the heating elements.

Abstract: A method for electrosurgically sealing a tissue includes steps of: (A) applying an initial pulse of RF energy to the tissue, the pulse having characteristics selected so as not to appreciably heat the tissue; (B) measuring a value of an impedance of the tissue in response to the applied pulse; (C) in accordance with the measured impedance value, determining an initial set of pulse parameters for use during a first RF energy pulse that is applied to the tissue; and (D) varying the pulse parameters of individual ones of subsequent RF energy pulses in accordance with at least one characteristic of an electrical transient that occurs during subsequent RF energy pulses. The method terminates the generation of subsequent RF energy pulses upon a determination that the electrical transient is absent or that a minimum output voltage has been reached.

Abstract: An arthroscopic probe with a distally orientated concave curve which constrains tissue is disclosed. It is particularly adapted to cutting ligaments and tendons. Also disclosed is a thermal energy delivery apparatus that includes (a) a probe with a distal end and a proximal end, (b) a first electrode positioned at the distal end of the probe and (c) a cabling coupled to the proximal end of the probe.

Abstract: When a user steps on a footswitch, high-frequency output power is delivered. A control circuit included in a diathermic power supply calculates the impedance ZSn that is offered by a living tissue immediately after delivery of high-frequency output power is started during the n-th delivery period. The control circuit also calculates the impedance ZEn that is offered thereby immediately before delivery of high-frequency output power is discontinued with elapse of predetermined time. The control circuit then discontinues delivery of high-frequency output power for the predetermined time, and calculates a difference &Dgr;Az between the impedances. When the difference meets a predetermined condition that implies coagulation or when the number of times of delivery reaches a predetermined value, the control circuit discontinues delivery of high-frequency output power.

Abstract: An electrosurgical apparatus supplies high-frequency power from a high-frequency power supply unit to an instrument placed in association with an organic tissue to dissect or coagulate the organic tissue. An impedance calculating section calculates the impedance value of the organic tissue. A rate-of-impedance-change calculating section calculates the rate of impedance change of the organic tissue based on the impedance value calculated by the impedance calculating section. A control section controls the high-frequency output of the high-frequency power supply unit based on a predetermined condition provided by combining the impedance value calculated by the impedance calculating section with the rate of impedance change calculated by the rate-of-impedance-change calculating section.

Abstract: An electrosurgical system including an electrode assembly having two electrodes for use immersed in an electrically conductive fluid has a generator with control circuitry for rapidly reducing the delivered radio frequency output power by at least 50% within at most a few cycles of the peak radio frequency output voltage reaching a predetermined threshold limit. In this way, tissue coagulation can be performed in, for example, saline without significant steam generation. The same peak voltage limitation technique is used in a tissue vaporization or cutting mode to limit the size of the steam pocket at the electrodes and to avoid electrode burning. In a blended mode, the output voltage is alternately limited to a value appropriate for coagulation and a value appropriate for cutting or vaporization.

Abstract: Ultrasonic instruments, and particularly solid core ultrasonic instruments, are advantageous because they may be used to cut and/or coagulate organic tissue using energy in the form of mechanical vibrations transmitted to a surgical end-effector at ultrasonic frequencies. The present invention provides a surgical instrument including force feedback system, in a closed loop arrangement that modulates the force applied to tissue from a surgical instrument. A generator provides electrical energy to the surgical instrument and an electrical signal representative of the generator load. The surgical instrument includes a handle that includes an actuating lever, and an end-effector located at the distal end of the handle. A force responsive element is operatively coupled to the actuating lever and the end-effector, wherein the force responsive element is adapted to alter a force on the end-effector in response to the electrical signal from the generator.

Abstract: In an electrosurgical instrument susceptible to varying load impedance, particularly varying load reactance, a fixed frequency radio frequency generator has an output stage (Q1, Q2, TR2-TR4, C1, VC2, 42) consisting of at least one output power device and, coupled to the power device, an output network with a load-dependent resonant condition. To compensate for variations in the load reactance, the output network has a dynamically variable capacitor (VC2) which maintains the tuning of the network substantially constant. Variation of the capacitor (VC2) is performed by means of a phase comparator and servo device (44) which are responsive to variations in phase difference occurring in the output stage due to load reactance changes.

Abstract: During an ablation procedure in a chamber of the heart RF energy is used to form a myocardial lesion for treatment of some arrhythmias such as sustained supraventricular tachycardia and accessory pathways. A galvanic cell formed by a metallic electrode having a first work function at the ablation site, a second metallic electrode having a second work function located remote from the ablation site and the intervening tissue serving as an electrolyte, produces an output current signal reflective of the formation of a lesion at the ablation site and is used to control the RF energy applied. A curve depicting the output current signal has a maximum value at the point a burn or lesion formation and thereafter decreases in value. A short duration inflection or bump of the curve occurs prior to charring and carbonization of the lesion.

Abstract: An electric operation apparatus including: a high frequency current generating circuit for feeding a high frequency current to electrodes; a direct power supply circuit for supplying variable electric power to the high frequency current generating circuit; a therapeutic condition monitoring circuit for monitoring a therapeutic condition brought about by the high frequency current on the basis of the high frequency current outputted by the high frequency electric current generating circuit; and a supplied power setting circuit for supplying a setting signal for supplied electric power to the power supply circuit on the basis of the monitoring results obtained by the therapeutic condition monitoring circuit.

Abstract: An electric medical apparatus according to the present invention performs an incising treatment automatically after the coagulating treatment has been performed without a necessity for an operator to perform another operation between the two treatment operations when the incising treatment performs after a coagulating treatment. The electric medical apparatus comprises a CPU, a waveform generating circuit, an amplifier and an output control unit to supply an output for performing the coagulating treatment to a treatment device and an output for performing the incising treatment to the treatment device. The impedance of a living tissue with which the treatment device is brought into contact is measured and calculated by a voltage sensor, a current sensor and an impedance calculating portion.

Abstract: During the treatment of biological tissues by high-frequency surgery, contaminants, in particular smoke, are produced. In the present invention a suction device for removal of the contaminants is controlled in such a way that it becomes active only when a voltage sufficient to ignite an arc exists at an applicator of the HF-surgery device, and/or an arc is burning between the applicator and the treatment region, and/or the treatment region reaches a temperature at which smoke can be produced.

Abstract: A high frequency power supply for applying electrical energy to a target site on or within a patient's body includes an electrical output driver, an output current sensor detecting the current output from the driver, and a power limiting device coupled to the current sensor during normal conditions, the power limiting device operates on a continuous basis. When current output exceeds a predetermined threshold level, the power limiting device is adapted to reduce power on the output driver to a standby mode. The power limiting device operates on a periodic detection or duty cycle when in the standby mode. The power limiting device switches into the stand-by mode to prevent excessive power drains. The power supply operates at a low power, pulsatile manner when an attached probe is in conductive or isotonic fluid but is not engaging body tissue or near a high impedance source. In this pulsatile mode, the power supply operates in a cyclical manner, typically at a predetermined duty cycle.

Abstract: An electrosurgical system including an electrode assembly having two electrodes for use immersed in an electrically conductive fluid has a generator with control circuitry for rapidly reducing the delivered radio frequency output power by at least 50% within at most a few cycles of the peak radio frequency output voltage reaching a predetermined threshold limit. In this way, tissue coagulation can be performed in, for example, saline without significant steam generation. The same peak voltage limitation technique is used in a tissue vaporization or cutting mode to limit the size of the steam pocket at the electrodes and to avoid electrode burning.

Abstract: This invention is an improved method and apparatus for tissue electrical impedance determination and electrical power control in a surgical device. In an embodiment of the invention an apparatus for controlling power delivery in an electro-surgical instrument is disclosed. The electro-surgical instrument includes a first channel and a second channel for delivery of energy to a surgical site. The apparatus includes: a switch, a measuring unit, a processor and a drive unit. The switch electrically isolates the second channel during a first measurement interval and the first channel during a second measurement interval. The measuring unit is coupled to the first and the second channel. The measurement unit measures a first power level of the first channel during a first measurement interval and a second power level of the second channel during a second measurement interval. The processor is coupled to the measuring unit and to the switch.

Abstract: The invention relates to an ablation apparatus for intracardiac treatments which comprises a high-frequency source whose power output is controlled in a power-or temperature-controlled mode. Ablation catheters which each comprise at least one energy-emitting pole can be used with the apparatus, the or each pole comprising at least one temperature sensor for measuring the temperature of a tissue. The temperature sensors of the poles are either thermistors or thermocouples. The instrument further comprises a sensor-detection system and corresponding devices by means of which the power output can be automatically regulated such that the power is regulated according to the actual catheter type. To that end, it is not necessary to use a specially coded catheter and no special manual operations are necessary for adjusting the catheter type.

Abstract: The present disclosure provides a method for determining the probability of a patient burn under a return electrode in a momopolar electrosurgical system comprising calculating a heating factor adjacent the return electrode utilizing a first algorithm, calculating a cooling factor adjacent the return electrode utilizing a second algorithm, subtracting the calculated cooling factor from the calculated heating factor to obtain a difference value, comparing the difference value to a threshold value, and adjusting the power dependent on the relationship of the difference value to the threshold value.

Abstract: A system for applying high frequency electrical energy to a body structure within a patient where the system detects the presence of conductive fluid. In one embodiment, the system includes a high frequency power supply, a surgical instrument having an electrode terminal, and a conductive fluid sensor coupled to the probe for detecting the presence of conductive fluid near the electrode terminal. The surgical instruments preferably has a shaft with a distal end and a proximal end, an electrode terminal on or near the distal end, and a connector coupling the electrode terminal to the power supply. The conductive fluid sensor may comprise of an electric switch adapted to create an open circuit when in contact with conductive fluid. Alternatively, the conductive fluid sensor may be a resistor that changes resistance when in contact with conductive fluid. The sensor detects for conductive fluid such as body fluid or saline solution. For devices having an active and return electrode (i.e.

Abstract: An electrosurgical generator control responds to tissue impedance between active and return electrodes during desiccation. Active and return generator leads to supply energy and a user control sets the level of energy desired for electrosurgery. Voltage and current sensing circuits respond to high frequency energy in the leads to signal voltage and current in the leads. A multiplier receives the signals to calculate power. A clock sets units of time during for which power calculation. An integrator calculates the energy supplied through the leads per time unit. The user control sets a reference signal for the energy level desired. A correlation circuit receives the energy calculations from the integrator and the reference signal and provides a feedback signal to indicate when the energy calculation equals the user control setting for altering the generator supply of energy to the leads.

Abstract: An automatic circuit that controls a surgical instrument having a pair of bipolar electrodes. The circuit comprises means for measuring the current between the pair of electrodes, an impedance detection circuit in electrical communication with the current measuring means, a comparator in electrical communication with the impedance detection circuit and a controller electrically connected to the comparator. The impedance detection circuit calculates the impedance between the electrodes based on the measured current and generates a first signal indicative of the calculated impedance. The comparator processes the first signal and generates an activation signal if the calculated impedance falls within a predetermined range of impedance values and generates a deactivation signal if the calculated impedance exceeds a deactivation threshold.

Abstract: The invention is an improved phacoemulsification probe drive circuit for supplying electrical power to an ultrasonic transducer. The drive circuit has a power control loop and a frequency control loop. The power control loop has a variable gain amplifier whose output is an input to a power amplifier. After the power amplifier amplifies power, power is delivered to a transformer and, thereafter, to a transducer. The voltage and current applied to the primary of the transformer are sensed to generate a signal proportional to the power (real or apparent) and the result is compared against a power command originating from a foot pedal. Once compared, the result of this comparison is sent to a first controller which acts upon the information by sending a corrective signal to the variable gain amplifier. Also, the phase of the voltage and current waveforms applied to the primary of the transformer are sensed by a phase detector.

Abstract: A method is described for the operation of a radiofrequency ablation instrument comprising a radiofrequency energy source having a plurality of regulatable outputs, with a plurality of electrodes being connectable to its outputs. A respective power value and/or current value representative of the power and/or the current transmitted by the radiofrequency energy source is detected for each output. The voltage delivered from the radiofrequency energy source is regulated in dependence on the detected power value and/or current value in such a way that the latter corresponds substantially to a predetermined power value and/or current value. A predetermined phrase relationship is in each case maintained between the currents or between the voltages at the outputs of the radiofrequency energy source. Furthermore, a corresponding apparatus is described.

Abstract: A catheter for use in an electrophysiological procedure to ablate a site includes a metallic tip having a first work function and energized by a source of RF energy. The RF energy return path is through a relatively large plate of a metallic material having a second work function and disposed at a location removed from the ablation site. The difference in work functions of the tip and the plate, operating in the presence of an electrolyte represented by the intermediate tissue, produces an exchange of electrical charges through chemical reaction to create a galvanic cell. By loading the galvanic cell with a shunt resistor, it becomes a current source providing a current linear with and highly dependent on the tissue temperature at the ablation site. This accurate representation of the tissue temperature at the ablation site is used to regulate the RF energy applied to maintain the tissue at the ablation site at a predetermined temperature during the ablation procedure.

Abstract: A high frequency power supply for applying electrical energy to a target site on or within a patient's body includes an electrical output driver, an output current sensor detecting the current output from the driver, and a power limiting device coupled to the current sensor during normal conditions, the power limiting device operates on a continuous basis. When current output exceeds a predetermined threshold level, the power limiting device is adapted to reduce power on the output driver to a standby mode. The power limiting device operates on a periodic detection or duty cycle when in the standby mode. The power limiting device switches into the stand-by mode to prevent excessive power drains. The power supply operates at a low power, pulsatile manner when an attached probe is in conductive or isotonic fluid but is not engaging body tissue or near a high impedance source. In this pulsatile mode, the power supply operates in a cyclical manner, typically at a predetermined duty cycle.

Abstract: Disclosed herein is a new arthroscopic probe with a concave distal tip which simultaneously constrains and cuts tissue. It is particularly adapted to cutting ligaments and tendons. Also disclosed is a thermal energy delivery apparatus which includes (a) a probe means with a distal end and a proximal end, wherein the distal end has a concave tip; (b) a first electrode means positioned at the distal end of the probe means, wherein the first electrode means is configured to deliver sufficient thermal energy to cut ligaments or tendons; and (c) a cabling means coupled to the proximal end of the probe means.In another embodiment of the invention a controller for controlling the delivery of energy and liquid to a surgical instrument with a temperature sensor is disclosed. The energy is supplied by an energy source and the liquid is supplied by a pump. The controller includes a temperature and a flow regulator. The temperature regulator is coupled to the energy source and coupled to the pump.

Abstract: Methods and apparatus are provided for welding or sealing vessels or organs by collapsing and elongating a vessel with a jaw-like structure, and then applying an RF current between first and second bi-polar electrodes to weld the approximated vessel walls together. The jaw-structure is configured to progressively collapse the section of tissue to squeeze fluids out of the lumen of the vessel. The device also may include one or more sensors providing signals to a power controller that modulates application of RF energy to the vessel based on power, temperature or tissue impedance.

Abstract: Methods and apparatus are provided for welding or sealing vessels or organs by collapsing a vessel with a jaw-like structure, applying an RF current between first and second bi-polar electrodes, and directing path of the RF current using a channeling electrode disposed intermediate the first and second bi-polar electrodes. The jaw-structure may be configured to progressively collapse the section of tissue to may squeeze fluids out of the lumen of the vessel. In addition, the jaw-structure may be configured to elongated the collapsed section of vessel to alter its impedance characteristics prior to application of RF energy. The device also may include one or more sensors providing signals to a power controller that modulates application of RF energy to the vessel.

Abstract: A multi-electrode probe for use with a catheter in an electrophysiological procedure to map and to ablate any of several tissue sites without repositioning the probe includes at least a plurality of electrodes, such as a tip and metallic rings, less than all of the electrodes has a first work function and are selectively energized by a source of RF energy. The RF energy return path is through a further electrode(s) of a metallic material having a second work function and disposed at a tissue location removed from the ablation site. After the sites have been mapped and one or more sites are selected for ablation, the selected site(s) is ablated prior to any repositioning of the probe. Regulation of the temperature at the ablation site(s) is achieved by sensing the temperature dependent current of a galvanic cell created by the tissue between the energized tip/ring and the further electrode due to their different work functions.

Abstract: Methods and apparatus are provided for welding or sealing vessels or organs by collapsing a vessel with a jaw-like structure, applying an RF current between first and second bi-polar electrodes, and directing path of the RF current using a channeling electrode disposed intermediate the first and second bi-polar electrodes. The jaw-structure may be configured to progressively collapse the section of tissue to may squeeze fluids out of the lumen of the vessel. In addition, or alternatively, the jaw-structure may be configured to elongated the collapsed section of vessel to alter its impedance characteristics prior to application of RF energy. The device also may include one or more sensors providing signals to a power controller that modulates application of RF energy to the vessel.

Abstract: During an ablation procedure in a chamber of the heart RF energy is used to form a myocardial lesion for treatment of some arrhythmias such as sustained supraventricular tachycardia and accessory pathways. A galvanic cell, formed by a metallic electrode having a first work function at the ablation site, a second metallic electrode having a second work function located remote from the ablation site and the intervening tissue serving as an electrolyte, produces an output current signal reflective of the formation of a lesion at the ablation site and is used to control the RF energy applied. A curve depicting the output current signal has a maximum value at the point a burn or lesion begins and thereafter begins to decrease in value. A short duration inflection or bump of the curve occurs prior to charring and carbonization of the lesion and predicts lesion formation of a sufficient depth. Thereafter, RF energy should no longer be applied to prevent unnecessary damage to the myocardial tissue.

Abstract: An ablation apparatus system for treating tissues in a patient, the ablation apparatus comprising temperature sensing means for measuring a temperature, wherein said temperature sensing means comprises a temperature sensing probe and at least one temperature sensing wire secured to the temperature sensing probe; force measuring means for measuring force exerted onto the temperature sensing probe by a tissue; and RF current generating means for generating RF current, wherein the RF current generating means is connected to and controlled by the temperature sensing means and force measuring means, adapted for supplying RF current to the temperature sensing probe as an electrode for tissue treatment.

Abstract: Systems and associated methods for ablating body tissue employ an electrode for contacting tissue to form a tissue-electrode interface. The electrode is adapted to be connected to a source of ablation energy to conduct ablation energy for transmission by the electrode into tissue at the tissue-electrode interface. The systems and methods also include an element to cool the electrode. The systems and methods hold a tissue temperature sensing element in a carrier in thermal conductive contact with tissue beneath the tissue-electrode interface. The systems and methods include a controller that is coupled to the tissue temperature sensing element to control either the supply of ablation energy, or the rate at which the electrode is cooled, or both based, at least in part, upon temperature sensed by the temperature sensing element.

Abstract: In an electric operation apparatus, a counter plate of a mono-polar type and a counter plate of a separate type are used to perform an electric operation. A counter plate connector connects a counter plate of a mono-polar type and a counter plate of a separate type. A first monitor is connected to the counter plate connector, and monitors the condition of the counter plate of the mono-polar type. A second monitor is connected to the counter plate connector, and monitors the condition of the counter plate of the separate type. A detector makes the first and second monitors operate on the basis of a predetermined operation procedure, thereby to detect the attachment conditions of the counter plates of respective types connected to the counter plate connector.

Abstract: A catheter for use in an electrophysiological procedure to ablate a site includes a first electrode having a first work function and energized by a source of RF energy. A second electrode having a second work function is disposed adjacent tissue. The difference in work functions of the first and second electrodes, operating in the presence of an electrolyte represented by intermediate tissue, produces an exchange of electrical charges through chemical reaction to create a galvanic cell. The galvanic cell serves as a current source to provide a unique electrode signal used to regulate the RF energy applied to the first electrode.

Abstract: An electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated. The advantage of the power control system is that thermal spread and charring are reduced. In addition, the power control system offers improved performance for electrosurgical vessel sealing and tissue welding. The output power is applied cyclically by a control system with tissue impedance feedback. The impedance of the tissue follows the cyclic pattern of the output power several times, depending on the state of the tissue, until the tissue becomes filly desiccated. High power is applied to cause the tissue to reach a high impedance, and then the power is reduced to allow the impedance to fall. Thermal energy is allowed to dissipate during the low power cycle. The control system is adaptive to tissue in the sense that output power is modulated in response to the impedance of the tissue.

Abstract: Systems and methods for ablating body tissue use an ablation element for contacting tissue to form a tissue interface. The ablation element is adapted to be connected to a source of ablation energy to conduct ablation energy for transmission by the ablation element into tissue at the tissue interface. The systems and methods include a tissue temperature sensing element held in a carrier in thermal conductive contact with tissue beneath the tissue interface. A mechanism attached to the carrier selectively advances the carrier relative to the ablation element to different depths beneath the tissue interface. A controller is coupled to the mechanism and to the tissue temperature sensing element to control advancement of the carrier beneath the tissue interface based, at least in part, upon tissue temperatures sensed by the sensing element beneath the tissue interface. Preferably, the controller controls the mechanism to locate the sensing element at the depth where the hottest sensed tissue temperature exists.

Abstract: The present invention relates to a high-frequency surgical generator (1) for adjusted cutting and coagluation having adjustment devices for setting the momentary electric output values, such as, e.g., current, voltage and power and having a device for direct and/or indirect determination of the state of the tissue in the vicinity of the cutting electrodes.