Abstract: Systems and methods are provided for priming or purging an electrosurgical fluid irrigation system. The electrosurgical system can include a high frequency power supply, a fluid delivery system, a handheld device having one or more electrodes, and one or more connectors for connecting the handheld device to the fluid delivery system and the RF generator. The electrosurgical system may be configured to deliver RF current and irrigation fluid until a threshold current level is detected, which is indicative of a continuous flow of fluid at the electrode and purging completion. The systems and methods of purging an electrosurgical system may further include dynamically controlling an RF output and fluid delivery system in accordance with varied parameters of detected threshold current levels.

Abstract: A method and apparatus include determining a value of a parameter associated with operation of an electrosurgical probe having a particular probe design, and determining whether the value of the parameter is within a range of values that has been predetermined for the particular probe design to indicate that the probe is treating tissue in a desired manner. Power is delivered to the probe according to an algorithm based upon a determination that the value of the parameter is outside the range of values The algorithm delivers power in a pulsed profile including portions of low power and portions of high power. In one embodiment, the tissue treatment is ablation, the parameter is impedance, and the method limits tissue necrosis to less than 200 microns. In another embodiment, the tissue treatment is shrinkage, the parameter is temperature, and the method limits power delivery when the probe is not shrinking tissue.

Abstract: A microwave system for generating microwave energy to tissue according to an energy control algorithm is disclosed. The system includes a microwave generator configured to select an energy control algorithm, programmed in the microwave generator that corresponds to a microwave energy delivery device connected to the generator.

Abstract: A medical device system includes at least one controllable patient-worn or patient-carried medical device, and a plurality of controller devices that are capable of independently controlling features or functions of the patient medical device. Control commands and other data is wirelessly communicated among the patient medical device and the multiple controller devices. A number of techniques, protocols, and other measures are provided to coordinate wireless communication between the various devices in a medical device system. These control command coordination processes address situations where conflicting, redundant, or concurrent control commands might be independently issued by the multiple controller devices.

Abstract: A high frequency generator connected to an electrosurgical instrument comprising an electrical output terminal, a power source electrically connected to the output terminal, an arc detector, and a power control for controlling the electrical power delivered through the output terminal. The power control initially causes the delivery of a high output power for a phase for initial cutting support and thereafter, if ignition of an arc has occurred for a predetermined period of time to cause the delivery of reduced or no power and subsequently for a predetermined period of time to cause the delivery of reduced or no 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 reduced or no power for a predetermined period of time of a short pause interval.

Abstract: A surgical system includes: a treatment portion for treating living body tissue targeted for treatment; an ultrasound supplying section for supplying ultrasound via ultrasound transducers which produce ultrasound vibration; a radio-frequency electrical power supplying section for supplying, to the treatment portion, radio-frequency electrical power having an output wave-form defined by a base frequency and a repetition frequency; and a controlling section for controlling at least one of a voltage root-mean-square value and a crest factor, so that the voltage peak value of the output wave-form of the radio-frequency electrical power does not exceed a fixed value.

Abstract: An electrosurgical generator system includes an electrical generator having an RF stage for outputting electrical energy having at least one waveform for performing an electrosurgical procedure. The system further includes at least one control module executable on at least one processor which controls at least one parameter of the outputted electrical energy and a configuration controller operably associated with the electrical generator which generates configuration data to configure the at least one control module to provide at least one modality of control of the outputted electrical energy based on the configuration data.

Abstract: An electrosurgical generator for supplying electrosurgical energy to tissue is disclosed. The generator includes sensor circuitry configured to measure an imaginary impedance and/or a rate of change of the imaginary impedance of tissue. The generator also includes a controller configured to regulate output of the electrosurgical generator based on the measured imaginary impedance and/or the rate of change of the imaginary impedance.

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: An electrosurgical generator may reduce unintended tissue damage by improving regulation of output power. The electrosurgical generator may control the power during a cycle, and react to a change in power if arcing occurs. Voltage sources, especially, demonstrate the tendency to have large, uncontrolled power excursions during normal electrosurgical use. The magnitude of the power excursions may be dependent on various factors. An exemplary electrosurgical generator control scheme reduces or minimizes the thermal spread by accurately supplying the specified power within a few cycles. Additionally, fast and accurate regulation provided by the constant voltage mode reduces or minimizes unintentional tissue charring. Thus, reduced thermal spread and charring should result in better surgical outcomes by reducing scarring and decreasing healing times.

Abstract: A system, apparatus and method for dissipating standing waves in a microwave energy delivery system including a microwave energy source configured to intermittently delivery microwave energy as a periodic microwave signal an energy delivery network configured to transmit the periodic microwave signal and a circuit connected between the microwave energy source and the energy delivery network. The circuit is configured to pass the periodic microwave signal from the microwave energy source to the energy delivery network when the periodic microwave signal is present and to dissipate standing waves when the periodic microwave signal is absent.

Abstract: A method of applying ablation energy to achieve transmurality including applying ablation energy at a starting power to a tissue site and monitoring the impedance of the tissue site. A power applied to the tissue site can be reduced as a function of a rate of an increase in impedance according to some embodiments.

Abstract: An electrosurgical system is disclosed. The electrosurgical system includes an electrosurgical generator adapted to supply electrosurgical energy to tissue. The electrosurgical generator includes impedance sensing circuitry which measures impedance of tissue, a processor configured to determine whether a tissue reaction has occurred as a function of a minimum impedance value and a predetermined rise in impedance, wherein tissue reaction corresponds to a boiling point of tissue fluid, and an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue. A tissue cooling period is provided to enhance operative outcomes.

Abstract: A method for controlling an electrosurgical waveform includes the initial steps of activating an electrosurgical generator and increasing power during a first sample window and determining a direction of change in a first average impedance during the first sample window. The method also includes the steps of performing a first adjustment of power in response to the direction of change in the first average impedance during a subsequent sample window and determining a direction of change in a subsequent average impedance during the subsequent sample window in response to the first adjustment of power. The method also includes performing a subsequent adjustment of power in response to the direction of change in the subsequent average impedance, wherein the subsequent adjustment of power is reverse to that of the first adjustment of power when the direction of change in the first and subsequent average impedances is the same.

Abstract: A method for controlling energy applied to tissue as a function of at least one detected tissue property includes the initial step of applying energy to tissue. The method also includes the steps of initially adjusting the energy applied to tissue and determining a direction of change of the at least one detected tissue property.

Abstract: A method for controlling an electrosurgical generator configured to apply energy to tissue as a function of a detected tissue property is contemplated by the present disclosure. The method includes the step of applying energy to the tissue in a first state, wherein the first state is configured to adjust the power output of the generator to continuously achieve peak tissue conductance as a function of the detected tissue property. The method also includes the step of monitoring a trend of the at least one detected tissue property indicative of a bubble field formation during a second state, which is running concurrently with the first state. The second state is configured to interrupt the bubble field to collapse the bubble field based on the trend of the at least one detected tissue property.

Abstract: A method for controlling energy applied to tissue in two or more states as a function of a detected tissue property is provided. The method includes the steps of: determining an initial value of the detected tissue property, recursively processing the detected tissue property to obtain an averaged value thereof, updating the recursively processing step with the initial value of the detected tissue property and transitioning between two or more states based on a comparison of averaged values obtained by two or more recursive filters.

Abstract: An electrosurgical system for treating tissue is disclosed. The system includes an electrosurgical generator, a printed circuit board, a generator ground and a patient ground. The printed circuit board is disposed in mechanical cooperation with the electrosurgical generator and includes a plurality of conductive layers. The generator ground includes a first portion and a second portion. The first portion is electro-mechanically connected to a conductive layer of the printed circuit board and the second portion is electro-mechanically connected to another conductive layer of the printed circuit board. The patient ground includes a portion that is at least partially interposed between the first portion of the generator ground and the second portion of the generator ground.

Abstract: A method with apparatus for performing surgery using plasma is described. In one exemplary embodiment, the apparatus includes a radiofrequency signal generator, a conditioning network coupled to the radiofrequency signal generator, and a catheter coupled to the conditioning network, the catheter including at least one electrode, such that the conditioning network conditions radiofrequency energy produced by the radiofrequency signal generator to create plasma at the at least one electrode of the catheter. Such novel plasma ablation system provides the capability to create high precision ablation with minimal damage to adjacent structures in numerous types of matter while employing multiple operation platforms including catheter based plasma application.

Abstract: The invention features compact apparatuses useful in electrosurgery. The compact apparatuses have a housing having a cavity, an electrosurgical system located within the cavity, the electrosurgical system having optionally a monopolar output system, optionally a bipolar output system, optionally an argon plasma coagulation output system, a processor located within the cavity, the processor operatively coupled to each output system of the electrosurgical system to control outputs generated by each output system, optionally a high frequency generator located within the cavity and operatively coupled to the processor; and a gas canister holder and control system located within the cavity of the housing for receiving a gas canister within the cavity of the housing.

Abstract: Methods and apparatus for delivering, monitoring, balancing, and/or dispersing high-frequency current flow in monopolar electrosurgery. The methods generally include positioning an active electrode in or on target tissue, positioning at least two dispersive electrodes on tissue remote from the target tissue, establishing electrical current flow from the active electrode through the dispersive electrodes, and individually adjusting the current through at least one of the dispersive electrodes to balance the current through the dispersive electrodes. By adjusting and balancing the current through two or more dispersive electrodes, safety of electrosurgical systems may be enhanced by preventing unwanted patient burns.

Abstract: An energy delivery apparatus for delivering electrical energy at a target location, the energy delivery apparatus being usable in combination with a magnetic field. The energy delivery apparatus includes an electrical conductor, the electrical conductor having a substantially elongated configuration; an electrode for delivering the electrical energy at the target location, the electrode being electrically coupled to the electrical conductor and located at a predetermined location therealong; and a guiding element mounted to the electrical conductor in a substantially spaced apart relationship relative to the electrode, the guiding element including a magnetically responsive material. The energy delivery apparatus is constructed such that a movement of the guiding element causes a corresponding movement of the electrode. The magnetic field is used to move the guiding element in order to position the electrode substantially adjacent to the target location.

Abstract: An apparatus and method for performing surgery using plasma is described. In one exemplary embodiment, the apparatus includes a radiofrequency signal generator, a conditioning network coupled to the radiofrequency signal generator, and a catheter coupled to the conditioning network, the catheter including at least one electrode, such that the conditioning network conditions radiofrequency energy produced by the radiofrequency signal generator to create plasma at the at least one electrode of the catheter.

Abstract: An electrosurgical generator system includes an electrical generator having an RF stage for outputting electrical energy having at least one waveform for performing an electrosurgical procedure. The system further includes at least one control module executable on at least one processor which controls at least one parameter of the outputted electrical energy and a configuration controller operably associated with the electrical generator which generates configuration data to configure the at least one control module to provide at least one modality of control of the outputted electrical energy based on the configuration data.

Abstract: A method and apparatus include determining a value of a parameter associated with operation of an electrosurgical probe having a particular probe design, and determining whether the value of the parameter is within a range of values that has been predetermined for the particular probe design to indicate that the probe is treating tissue in a desired manner. Power is delivered to the probe according to an algorithm based upon a determination that the value of the parameter is outside the range of values The algorithm delivers power in a pulsed profile including portions of low power and portions of high power. In one embodiment, the tissue treatment is ablation, the parameter is impedance, and the method limits tissue necrosis to less than 200 microns. In another embodiment, the tissue treatment is shrinkage, the parameter is temperature, and the method limits power delivery when the probe is not shrinking tissue.

Abstract: The disclosure describes a user interface that may be used to control ablation therapy and monitor ablation therapy progress in systems that utilize wet electrode ablation techniques. The user interface presents a virtual electrode depth icon to a user that indicates the size of a lesion that may be created with the selected virtual electrode depth. The virtual electrode depth may be changed by the user according to the ablation therapy most appropriate for a patient, and the user may interact with the user interface to define the virtual electrode depth. In this manner, the user interface may be a touchscreen or other input device such as a mouse, pointing device, or keyboard. The user interface may also provide a thermometer icon that represents a patient temperature, a timer icon that represents a remaining time for therapy, and other representations of therapy progress.

Abstract: An electrosurgical system and method are disclosed. The system includes an electrosurgical generator adapted to supply electrosurgical energy to tissue. The generator is further adapted to supply an electrical signal having at least one substantially constant value to tissue to determine initial tissue impedance response. The generator includes sensor circuitry adapted to continuously monitor initial tissue impedance response, wherein the initial tissue impedance response includes one of an initial impedance, an impedance drop, an impedance minimum and a first impedance rise. The generator also includes a microprocessor adapted to generate at least one tissue parameter based as a function of the initial impedance, the impedance drop, the impedance minimum and the first impedance rise. The system also includes an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue for treatment.

Abstract: An electrosurgical pencil configured and adapted to support an electrocautery blade. A strain gauge is affixed to the proximal end of the electrocautery blade and measures the displacement of the blade as a result of resistance and drag acting on the blade. The electrosurgical pencil also includes a meter electrically connected to the strain gauge for monitoring either a change in voltage, a change in electrical current or a change in optical wavelength. The amount of blade displacement as measured by the strain gauge is available for display to the surgeon and/or as sensory input for a control circuit in the electrosurgical generator that modulates the generator output waveform. The electrosurgical pencil further includes a control circuit electrically coupled between the electrocautery blade and the electrosurgical generator. The control circuit is configured and adapted to control power supplied to electrocautery blade based on the displacement measured by the strain gauge.

Abstract: A method and system are disclosed enabling configuration of a control system for an electrosurgical generator system for creating new surgical applications without changing the underlying software system. The system includes an outer loop controller for generating a control signal in accordance with at least a first subset of sensor data from at least one sensor; an inner loop controller for generating a setpoint control signal which is provided to an RF stage in accordance with at least the control signal generated by the outer loop controller and a second subset of sensor data from the at least one sensor; and a configuration controller for generating configuration data and providing first and second configuration data sets of the configuration data to the inner loop and outer loop controllers, respectively, for configuration thereof to provide a type of control selectable from a variety of types of control.

Abstract: An electrosurgical system is disclosed comprising a generator configured to electrosurgical coagulation waveforms. The generator includes a closed loop control system for controlling the electrosurgical coagulation waveforms. The closed loop control system includes a sensor configured to sense a tissue property and/or an energy property and to transmit the tissue property and/or the energy property as one or more sensor signals having an amplitude. The control system also includes a gain controller configured to process the at least one sensor signal to reduce the amplitude of the sensor signals and to obtain a signal to noise ratio of the at sensor signals within a predetermine range. A microprocessor coupled to the generator and is configured to adjust the electrosurgical coagulation waveforms as a function of the sensor signals.

Abstract: The functionality and the output power delivered are evaluated in an electrosurgical generator by calculating first and second values related to the output power delivered by using separate first and second computations. The two calculated values are compared, and an error condition is indicated when the two values differ by a predetermined amount. The separate computations, coupled with the other separate activities of measuring, averaging and sampling the output current and voltage measurements, serve as an effective basis for detecting errors caused by malfunctions or equipment failure. The error condition may be used to as a basis to terminate the output power delivery or indicate the error.

Abstract: A method of applying ablation energy to achieve transmurality including applying ablation energy at a starting power to a tissue site and monitoring the impedance of the tissue site. The power applied to the tissue site can be increased in response to detection of a power plateau or application of a first power for a minimum time according to some embodiments. A power applied to the tissue site can be reduced in response to an increase in impedance according to some embodiments. Transmurality can be indicated in response to a transmurality plateau following a rise in impedance according to some embodiments.

Abstract: An electrosurgical instrument for treating tissue includes a housing having at least one tissue treating member attached thereto. The tissue treating member includes an electrically conductive tissue contacting surface connected to a source of electrosurgical energy such that the tissue contacting surface is capable of conducting electrosurgical energy to tissue. An energy conductive, ablative material is disposed on the electrically conductive tissue contacting surface and is configured to at least partially deplete during electrosurgical activation to reduce tissue adhesion.

Abstract: The invention is concerned with cauterizing and resecting tissue. A pair of electrodes are placed on opposed tissue surfaces, and radio frequency power is applied through the electrodes to cauterizing a tissue mass therebetween. After cauterization has been effected, the tissue may be resected along a plane within the cauterized region with minimum or no bleeding. The tissue mass may then be removed.

Abstract: An electrosurgical system is disclosed comprising a generator configured to electrosurgical coagulation waveforms. The generator includes a closed loop control system for controlling the electrosurgical coagulation waveforms. The closed loop control system includes a sensor configured to sense a tissue property and/or an energy property and to transmit the tissue property and/or the energy property as one or more sensor signals having an amplitude. The control system also includes a gain controller configured to process the at least one sensor signal to reduce the amplitude of the sensor signals and to obtain a signal to noise ratio of the at sensor signals within a predetermine range. A microprocessor coupled to the generator and is configured to adjust the electrosurgical coagulation waveforms as a function of the sensor signals.

Abstract: An electrosurgical system comprises a generator and an instrument including a first electrode, a second electrode, and an insulating spacer separating the first and second electrodes. The generator repeatedly measures a characteristic of the radio frequency output such as the impedance between the first and second electrodes. The generator analyses the impedance measurements, and interrupts the radio frequency signal when the rate of change of the impedance is such as to indicate the onset of a “flare-out”. In this way, the power is reduced before the flare-out leads to permanent damage or failure of the instrument.

Abstract: This disclosure describes impedance computation techniques that may reduce the effect of crosstalk, thus generating more accurate impedance measurements. In particular, an ablation system models the electrical interaction among the active electrodes and a common return electrode using a star-configuration resistor model. The ablation system computes one or more parameters of the star-configuration resistor model and adjusts the therapy based on at least the computed parameters of the star-configuration resistor model.

Abstract: An electrosurgical system comprising, among other things, a control console to which detachably connects one or more electrosurgical probes capable of coagulating and ablating tissue. The control console generates a selectively variable power signal having a duty cycle that is dynamically modulated so as to maintain an average power level of a probe that is lower than a predefined maximum power level. The system can also incorporate both an impedance monitoring system and a current monitoring system as means to detect potentially dangerous situations, as well as a monitoring system for detecting impedance at relatively low power levels upon first activation of the probe. The probe can also incorporate non-volatile memory for storing probe-specific operating parameter data, probe usage data, data restricting probe use, error codes, and control console updates.

Abstract: Methods and apparatus for delivering, monitoring, balancing, and/or dispersing high-frequency current flow in monopolar electrosurgery. The methods generally include positioning an active electrode in or on target tissue, positioning at least two dispersive electrodes on tissue remote from the target tissue, establishing electrical current flow from the active electrode through the dispersive electrodes, and individually adjusting the current through at least one of the dispersive electrodes to balance the current through the dispersive electrodes. By adjusting and balancing the current through two or more dispersive electrodes, safety of electrosurgical systems may be enhanced by preventing unwanted patient burns.

Abstract: The invention is concerned with cauterizing and resecting tissue. A pair of electrodes are placed on opposed tissue surfaces, and radio frequency power is applied through the electrodes to cauterizing a tissue mass therebetween. After cauterization has been effected, the tissue may be resected along a plane within the cauterized region with minimum or no bleeding. The tissue mass may then be removed.

Abstract: An electrosurgical generator apparatus controls a variable output signal to electrodes. The generator apparatus operates in a cut mode, a coagulation mode or a stimulate mode. The generator apparatus comprises a DC power supply that provides regulated low voltage and high voltage outputs and a radio frequency (RF) waveform generator circuit that provides pulse duration modulation (PDM) of a carrier signal. The carrier signal directly affects the variable output signal to the electrodes. A control circuit controls a variable output signal to electrodes used in electrosurgical procedures. The control circuit comprises a DC power supply circuit that provides regulated low voltage and high voltage outputs and an RF waveform generator circuit that provides pulse duration modulation of a carrier signal. The carrier signal directly affects the variable output signal to the electrodes.

Abstract: An electrosurgical generator has a control system formed by an array of logic gates programmed to execute mathematical algorithms for regulating at least one parameter of output power, output voltage or output current of an output electrosurgical signal in a closed loop response to sensed values of the output voltage and the output current.

Abstract: An electrosurgical system is disclosed. The electrosurgical system includes a multiple-secondary transformer configured for sensing voltage. The multiple-secondary transformer includes a primary winding coupled to an active terminal and a return terminal of the electrosurgical system and a plurality of secondary windings. Each of the secondary windings is configured to transform the radio frequency voltage into a sensed voltage. Each of the secondary windings includes an output coupled to a sensor circuit and configured to transmit the sensed voltage to the sensor circuit.

Abstract: An apparatus and method for cutting a material including conducting and non-conducting materials such as biological tissue, cellulose or plastic while the material is submerged in a conductive liquid medium. The apparatus has a cutting electrode with an elongate cutting portion having an aspect ratio (length to width) of 1 or more and a return electrode. The two electrodes are immersed in the conductive medium and a voltage is applied between them to heat the medium, thus producing a vapor cavity around the elongate cutting portion and ionizing a gas inside the vapor cavity to produce a plasma. The voltage applied between the electrodes is modulated in pulses having a modulation format selected to minimize the size of the vapor cavity, its rate of formation and heat diffusion into the material while the latter is cut with an edge of the elongate cutting portion. The modulation format includes pulses ranging in duration from 10 ?s to 10 ms, as well as minipulses and micropulses, as necessary.

Abstract: The invention concerns an HF-surgery device for cutting and/or coagulating biological tissue and a method for same, which in operation monitors the patient skin contact of a connected neutral electrode having at least two separate contact surfaces. The HF-surgery device includes at least one parallel resonant circuit arranged in a patient circuit, at least one measurement energy source arranged in a measurement circuit galvanically separated from the patient circuit for producing a measurement voltage/current acting between the contact surfaces of the neutral electrode, and at least one measuring and computing unit which in operation determines by means of the measurement voltage/current a tissue impedance which is representative of the patient skin contact and which acts between the contact surfaces. An HF-current flows in the patient circuit which is closed in the cutting or coagulation operation and the measurement voltage which is independent of the HF-current can be produced in the measurement circuit.

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: Voltage and current of an electrosurgical output signal which is conducted by a transformer are accurately simulated by executing a simulation algorithm to compensate for inherent distortion in the values of the current and voltage induced between primary and secondary windings of the transformer. The simulation algorithm is executed in response to voltage and current signals from a primary winding of the transformer, which may be a power output transformer or part of an electrosurgical output signal sensor.

Abstract: A polyphase electrosurgical system and method are provided. In embodiments, a radiofrequency generator having the capability of delivering a plurality of independent electrosurgical signals is disclosed. An electrosurgical instrument having an array of electrodes that correspond to the plurality of signals may be used to deliver the electrosurgical signals to tissue. In embodiments, three RF signals having a phase offset of about 120° therebetween, i.e., a three-phase configuration, may be used to achieve a balanced delivery of electrosurgical energy, which may lead to increased rates of energy delivery, improved control of tissue ablation regions, and improved operative outcomes. The phase, amplitude, and/or frequency of each signal may be independently variable in response to user inputs and/or biological parameters such as tissue impedance or return electrode current.

Abstract: A method and apparatus include determining a value of a parameter associated with operation of an electrosurgical probe having a particular probe design, and determining whether the value of the parameter is within a range of values that has been predetermined for the particular probe design to indicate that the probe is treating tissue in a desired manner. Power is delivered to the probe according to an algorithm based upon a determination that the value of the parameter is outside the range of values The algorithm delivers power in a pulsed profile including portions of low power and portions of high power. In one embodiment, the tissue treatment is ablation, the parameter is impedance, and the method limits tissue necrosis to less than 200 microns. In another embodiment, the tissue treatment is shrinkage, the parameter is temperature, and the method limits power delivery when the probe is not shrinking tissue.