WO1997040882A2 - Systemes et procedes d'optimisation de l'apport en energie radiofrequence pour la formation de lesions dans des tissus humains - Google Patents

Systemes et procedes d'optimisation de l'apport en energie radiofrequence pour la formation de lesions dans des tissus humains Download PDF

Info

Publication number
WO1997040882A2
WO1997040882A2 PCT/US1997/007311 US9707311W WO9740882A2 WO 1997040882 A2 WO1997040882 A2 WO 1997040882A2 US 9707311 W US9707311 W US 9707311W WO 9740882 A2 WO9740882 A2 WO 9740882A2
Authority
WO
WIPO (PCT)
Prior art keywords
tissue
temperature
electrode
energy
time
Prior art date
Application number
PCT/US1997/007311
Other languages
English (en)
Other versions
WO1997040882A9 (fr
WO1997040882A3 (fr
Inventor
John N. Hendrick
Laurent P. Bonnaure
Donald P. Kannenberg
Bruno Strul
Original Assignee
Vidamed Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vidamed Incorporated filed Critical Vidamed Incorporated
Priority to AU31168/97A priority Critical patent/AU3116897A/en
Publication of WO1997040882A2 publication Critical patent/WO1997040882A2/fr
Publication of WO1997040882A3 publication Critical patent/WO1997040882A3/fr
Publication of WO1997040882A9 publication Critical patent/WO1997040882A9/fr

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/40—Applying electric fields by inductive or capacitive coupling ; Applying radio-frequency signals
    • A61N1/403—Applying electric fields by inductive or capacitive coupling ; Applying radio-frequency signals for thermotherapy, e.g. hyperthermia
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B18/1485—Probes or electrodes therefor having a short rigid shaft for accessing the inner body through natural openings

Definitions

  • This invention relates generally to systems and methods for delivering radio frequency (RF) energy to an area of tissue within an organ for lesion formation and, more particularly, to improved systems and methods for optimizing the delivery of RF energy for lesion formation within human tissue.
  • RF radio frequency
  • Radio frequency (RF) ablation has heretofore been used particularly in cardiology for the treatment of cardiac arrhythmias and in neurosurgery for the relief of pain and other disorders.
  • RF energy for the treatment of benign prostate hyperplasia (BPH) in transurethral needle ablation procedures is disclosed in co-pending Application Serial No. 08/368,936 filed January 5, 1995 and Application Serial No. 08/588,452 filed January 18, 1996, both of which are hereby incorporated by reference as if fully set forth herein.
  • the critical factor which must be addressed is not the amount of RF energy provided to the area of tissue but, rather, the manner in which the RF energy is provided to the area.
  • the present invention is directed to improved systems and methods for delivering RF energy to an area of tissue within the human body, such that one or more lesions of a predetermined and, in some instances, maximum size may be produced in that area.
  • the systems and methods of the present invention provide for the formation of a lesion of maximum size within an organ or other selected area of tissue, such as the male prostate.
  • RF energy is delivered to one or more elec ⁇ trodes disposed within an area of tissue such that the temperature of the tissue surrounding the electrode (s) may be elevated in a controlled manner over a first period of time to a selected target value and, thereafter, main ⁇ tained at substantially the selected target value for a second period of time. In this manner, heat transfer through convection may be maximized and maximum lesion formation may be obtained.
  • the systems and methods of the present invention provide a second means for regulating the amount of RF energy applied to an electrode deployed within an area of tissue to insure that a sub ⁇ stantial amount of heat transfer within the area will be achieved via convection, thus allowing for maximum lesion formation.
  • the impedance of the tissue surrounding the electrode is monitored and, if it is determined that the rate of change of the impedance exceeds a predetermined value, the amount of RF energy delivered to the electrode(s) is reduced by a selected amount.
  • the present invention is directed to an improved microprocessor controlled RF generator system, which may be operated in either an automatic or manual mode, to effect optimal lesion formation within a selected organ or area of tissue.
  • the microprocessor may be configured to automatically control the amount of RF energy delivered to one or more electrodes deployed within a selected area of tissue in response to feedback signals indicative of the temperature and/or impedance of the tissue surrounding electrode(s) , such that maximum lesion formation is achieved within the area.
  • Fig. 1 is an isometric view of an apparatus utilized in effecting lesion formation within a human prostate in accordance with one embodiment of the present invention.
  • Fig. 2 is a graph illustrating a tissue heating profile in accordance with one form of the present inven tion.
  • Fig. 3 is a block diagram illustrating the elements comprising an RF generator in accordance with one form of the present invention.
  • Fig. 4 is a flow chart illustrating a series of software control functions which may be executed by the microprocessor of a RF generator system in accordance with the present invention.
  • Fig. 5 is a flow chart illustrating a series of software control functions which may be executed by the microprocessor of a RF generator system in accordance with a second preferred form of the present invention.
  • the present inven- tion is directed to an improved method for effecting lesion formation, via RF ablation, within a selected area or target volume of tissue. While the following discus ⁇ sion focuses primarily on improved methods for effecting lesion formation within the male prostate, it should be understood that the described methods are not limited to use within prostatic tissue but, on the contrary, may have application in a wide variety of tissues and/or organs.
  • the human male has a bladder with a base and a penis with a urethra therein formed by a urethral wall extending into the base of the bladder along a longitudinal axis with the tissue of the prostate surrounding the urethra near the base of the bladder.
  • a method of trans- urethral needle ablation may be performed by the use of an elongate probe member having proximal and distal extremi ties, wherein the probe member is sized so that it can be introduced into the urethra and has a length so that when the distal extremity of the elongate probe member is disposed in the vicinity of the prostate, the proximal extremity extends out of the urethra.
  • a control handle is coupled to the proximal extremity of the elongate probe member. At least one, but more preferably first and second stylets are slidably carried by the elongate probe member.
  • the control handle includes control means coupled to the first and second stylets for moving the first and second stylets through the urethral wall into the target volume of tissue in the prostate.
  • Each of the stylets has an electrode and an insulating sleeve surrounding the electrode, each of the electrodes being coupled to an RF energy power supply.
  • RF energy from the RF power supply may be provided to the electrodes to heat the tissue surrounding the electrodes in a controlled fashion to a final temper ⁇ ature of, for example, between 50°C and 60°C.
  • the RF energy is supplied over a first period of time (e.g., a rise time) ranging, for example, from 2 to 8 minutes to cause the temperature of the tissue in the prostate to rise, preferably in a substantially linear fashion, from an initial temperature to approximately the final temper ⁇ ature.
  • RF energy is supplied to maintain the prostatic tissue being ablated at or near the final temperature for a second period of time (e.g., a dwell time) of, for example, from 1 to 4 minutes.
  • a second period of time e.g., a dwell time
  • the system may comprise a transurethral needle ablation probe or catheter 12 which has mounted therein an optical device 13.
  • the probe or catheter 12 is connected by a cable 16 to a radio frequency (RF) generator 17.
  • RF radio frequency
  • a return electrode 18 is provided which is connected by a cable 19 to the RF generator 17.
  • a foot pedal 21 is provided which is connected by a cable 22 to the RF generator 17 for controlling the operation of the RF generator 17 as hereinafter described.
  • An optional rectal temperature monitoring device 26 is provided which is adapted to be connected by a cable 27 to the RF generator 17.
  • the transurethral needle ablation probe or catheter 12 can be of any suitable type such as those disclosed in earlier co-pending applications which are referenced in U.S. Patent Application Serial No. 08/368,936 filed on January 5, 1995 or, alternatively, it can be of the type disclosed in U.S. Patent Application Serial No. 08/588,452 filed on January 18, 1996.
  • a transurethral needle ablation probe or catheter 12, such as that shown in Fig. 1, may comprise a bridge assembly 31 which has removably mounted thereon an elon ⁇ gate rigid sheath 32 formed of a suitable material such as stainless steel and having a suitable size as for example 22 French.
  • the sheath 32 is provided with an oval-shaped bore 33 which extends from the bridge assembly 31 to a distal extremity 34 of the sheath 32 where the bore opens into an upwardly facing opening 36 provided in the sheath 32.
  • First and second stylets 41 and 42 extend through the bore 33 and through the upwardly facing opening 36 for the formation of lesions as hereinafter described.
  • a scale 38 is provided on the exterior of the sheath 32 making it possible to ascertain the distance the sheath 32 has been inserted into the urethra.
  • the first and second stylets 41 and 42 are of the type described in co-pending U.S. Patent Application Serial No. 08/588,452 filed January 18, 1996 and include a flexible electrode 43 covered by a movable or, if desired, stationary insulating sleeve 44 so that the electrode can be introduced into the prostate through the urethral wall with the insulating sleeve extending through the urethral wall and protecting the urethral wall during RF ablation.
  • the first and second stylets 41 and 42 extend through the bore 33 in the sheath 32 and into the bridge assembly 31.
  • the bridge assembly 31 includes a depending control handle 46 which carries a knob mechanism 47 coupled to the stylets 41 and 42 for controlling the deployment of the first and second stylets 41 and 42, either one at a time or in unison from the sheath 32.
  • Another knob 48 is provided for controlling the relative deployment between the electrode 43 and the insulating sleeve 44 of each stylet 41 and 42.
  • the optical device 13 is removably mounted in the bridge assembly 13 and includes rod lens optics (not shown) and has a distal extremity forming an eyepiece 57 as shown in Fig. 1 which is disposed adjacent the opening 36 to permit viewing of the first and second stylets 41 and 42 as they are deployed.
  • the optical device 13 also includes an eyepiece 57 to permit viewing by the human eye during the time that the transurethral needle ablation probe or catheter 12 is being utilized.
  • the optical device 13 is connected by an optical cable 58 to a light source 59.
  • the RF generator 17 may comprise a metal case 66 which is provided with an inclined front wall 67 that is labelled front panel 68.
  • the front panel 68 has a plurality of display areas 71 having associated indicia 72 as hereinafter described.
  • the RF generator 17 is provided with a power cord (not shown) which is connected through an on-off switch 76 mounted on a vertical panel 77 ad- joining the front inclined wall 67.
  • This front wall 67 carries a plurality of receptacles as shown for connection to the various cables hereinbefore described and as shown.
  • the RF generator 17 also includes electronics of the type disclosed in U.S. Patent No. 5,484,400 and in U.S. Patent Application Serial No. 08/314,190 filed on Septem ber 28, 1994, both of which are hereby incorporated by reference as if fully set forth herein.
  • the microprocessor of an RF generator in accordance with the present invention is configured or, stated different ⁇ ly, programmed to implement the methods described and claimed herein.
  • the RF generator 17 has the capability of supplying dual RF signals which are applied to the target prostate tissue through the first and second stylets 41 and 42.
  • the RF genera ⁇ tor 17 includes means for monitoring the temperature in the urethra at the proximal extremity of the insulating sleeve 44, as for example by a temperature sensor carried by the proximal extremity of the sleeve 44.
  • the RF generator 17 also includes means for monitoring the temperature of tissue in the prostate by temperature sensors carried by the distal extremity of the insulating sleeve for each of the first and second stylets 41 and 42, and means for monitoring an impedance of the tissue surrounding the first and second stylets 41 and 42.
  • tempera ⁇ tures can be monitored in the rectal area in the vicinity of the prostate, as for example as many as three spaced- apart electrodes can be carried by the rectal probe 26.
  • the methods of the present invention may be employed to perform a transurethral needle ablation procedure as described below.
  • the rigid sheath is introduced into the urethra so that the distal extremity is disposed in the vicinity of the prostate with the proximal extremity remaining extending out of the urethra by the physician's use of the control handle.
  • one or more of the stylets can be deployed through the urethral wall by operation of the knob assembly 47 so that the needle electrodes protrude through the urethral wall in a direction which is at substantially right angles to the longitudinal axis of the urethra and with the insu- lating sleeve of each stylet following the electrode so that the electrode is disposed in the tissue with the insulating sleeve still being disposed in the urethral wall to protect the urethral wall.
  • the amount of exten ⁇ sion of the electrode beyond the insulating sleeve is determined by the setting of the knob 48.
  • first and second stylets 41 and 42 are being disposed in the manner hereinbefore described, their positioning can be observed by the physician through the eyepiece 57.
  • RF energy may be supplied from the RF generator 17 in the manner hereinafter described either singly or in parallel and either in a monopolar mode in which the return path is through the electrode 18 and a bipolar mode in which the return path is through one of the stylets 41 and 42.
  • the stylets 41 and 42 can be retracted and the sheath 32 rotated to another angular position and the stylets 41 and 42 can be introduced into another lobe in a similar manner and RF energy supplied to the electrodes to ablate tissue in the other lobe of the prostate.
  • RF lesions are created in the prostatic tissue.
  • These lesions can be characterized in a number of ways, for example by their electrical characteristics, their thermal pathological characteristics and their thermal physiological characteristics.
  • the active electrode surface area of the needle electrode is much smaller than that of a dispersive electrode and therefore the current density is very high in the vicinity of the needle electrode as shown by Equation 1 below.
  • J current density (A/m 2 )
  • I intensity (A)
  • r distance (radius) from the needle (m)
  • 1 needle length (m) .
  • RF high frequency current is delivered from the electrode into the tissue to heat the tissue because of the resistance encountered. This typically only happens where the current density is high, i.e., up to 3 mm away from the needle electrode.
  • the mechanism of this resis ⁇ tive RF heating occurs because of the frequency of the current. Ions in the tissue around the needle electrode try to follow changes in the current direction of the alternating current. This agitation of the ions develops frictional heat and conductive heating.
  • the tissue being subjected to ablation by the needle electrode has a typical rugby-ball shape surrounding the needle. The cells in this rugby-ball shape are penetrated by the alternating currents produced by the RF energy.
  • Frequencies ranging from 300 kHz to 1 MHZ have been used for RF ablation of tissue.
  • Equation 2 establishes that the heat generated varies as L/R 4 which assumes cylindrical integration versus spherical integration, although spherical integration is more appropriate for the transurethral needle ablation geometry.
  • Equation 4 is not a steady state equation and is valid when secondary effects such as heat transfer to surrounding tissues or physiologic endothermic effects are negligible.
  • Equation 5 establishes that in each part in the lesion, the temperature is growing linearly with time. However at 1 mm away from the needle electrode where the major heating effect is known to be purely RF electrical, the temperature should then vary as 0.897 t. After a three-minute lesion, the temperature should therefore be in the 200°C range, which however does not occur. Audible pops do occur when the tissue is overheated and boils, after which it vaporizes or eventually chars. This indicates that other important thermal phenomena occur in the overall lesion formation to balance the effect of RF electrical direct heating.
  • T eleotrode temperature at the interface between the electrode and the tissue at a time t
  • T sCart temperature at the beginning of the le ⁇ sion, i.e., 37 deg C
  • a needle/tissue interface is at a temperature of approximately 90°C.
  • Equation 5 also shows that the control parameters for the RF electrical energy are not only the lesion time and the current density (or power) , but also by the contact area between the needle electrode and the tissue. Therefore, a good contact between the needle electrode and tissue is necessary. Improved results are obtained when the contact between the needle electrode and the prostatic tissue is constant.
  • the other RF induced effects will now be discussed, including the thermal, physiological and pathological effects.
  • the small portion of tissue heated by RF energy around the needle electrode acts as a heater to the remaining surrounding prostatic tissue and, as will be more fully described below, preferably causes that sur ⁇ rounding tissue to be heated in substantial part by convection.
  • This heating effect can be maintained by supplying low RF power to the needle electrode as during a dwell portion of a transurethral needle ablation proce dure as hereinafter described. From a macroscopic stand point, two thermal lesion zones, in addition to the RF electrical lesion hereinbefore discussed, are found in a transurethral needle ablation.
  • the pathological lesion is created by typical coagulation necrosis, and the physio ⁇ logical lesion surrounds the pathological zone or lesion with edema, hemorrhage and acute inflammation forming a gelatinous layer around the pathological zone.
  • This can be explained by considering that when one specific part of the tissue is progressively heated, it first develops into a physiological lesion at 45°C to 50°C. At this tempera ture, the protein chains change, the amino-acids crosslink and the electrophysiology properties change from a pro- gressive reversible depolarization of the cell to total irreversible loss of the cellular excitability and tissue injury as temperature increases.
  • This physiological injury is accompanied with edema, inflammation and loss of the water and of the ions in the tissue.
  • the cell plasma is liberated and creates a gelatinized layer which tries to protect the rest of the tissue against further heat damage.
  • the tissue reaches temperatures higher than 50°C, the tissue is reliably destroyed and the physiolog ⁇ ical lesion turns into a pathological lesion.
  • the main heat transfer in RF-induced thermal injuries is substantially solely convective.
  • the blood circulating in the prostate therefore has two opposite effects.
  • the blood vessels dissipate heat which limits the lesion size and two, the blood enhances convection which favors thermal lesion formation.
  • the blood flow in large vessels is not affected by the RF ablation.
  • the microcirculation ceases and RF-induced thermal damage desiccates the capillary blood vessels in the prostate and seals them.
  • Such blood would be constricted inside the lesion area and would be available to convect heat within the lesion and thus would lead to tissue necrosis.
  • Lesions in the prostate usually have a high plasma/water content. Because of the gradient of ion concentration within the overall lesion, diffusion and convection of ions (Na+, K+ and Ca++ mainly) occurs in accordance with Pick's law.
  • the pathophysiology of the RF-induced thermal lesion occurs principally because of convective heat transfer which explains the fairly large overall lesion size (up to 20 mm away from the needle electrode, whereas the RF electrical injury is only within 2 mm from the needle electrode) .
  • the physiological lesion area will progress or regress over time depending on the degree of injury in the lesion.
  • the region of acute physiological injury is more extensive than the acute pathological lesion which explains the critical late effects of a transurethral needle ablation in accordance with the present invention in which urinary flow may keep increasing even 12 months after the proce ⁇ dure.
  • the RF-induced thermal, physiological and pathological lesions are created by convection mechanism in which gelatinization, as herein ⁇ before described, creates a lag in the creation of the lesion.
  • the lesion volume was highly correlated with the energy delivered to the prostatic tissue except where the lesion volume was the greatest, even though the energy delivered may actually be very low.
  • This phenomena can be explained in that the tissue being treated may be in a thermal resonance mode with the three different types of heat transfer hereinbefore discussed in different areas of the tissue interacting, i.e., the conductive resistive heat for the RF electrical lesion, the convective heat for the RF-induced thermal physiological and pathological lesions and the latent gelatinization heat.
  • Thermal resonance modes can be described with thermal equations of the same nature as mechanical equations for mechanical resonance.
  • the RF energy is applied to tissue in the prostate serving as a heater so that the remainder of the tissue of the prostate being ablated will heat in phase (or with a 180° out-of-phase) and enter a resonance mode with the remain der of the tissue of the prostate.
  • the term "resonance" as used herein means that the energy is delivered to the prostatic tissue in a manner that matches the tissue characteristics.
  • the optimum control strategy for the RF generator 17 is to perform an RF ablation with a 4.0 minute temperature rise time and to hold this temperature for 1.5 minutes.
  • the targeted temperature is 60°C, but in case the tissue impedance starts to rise too soon, the temperature objec tive is lowered to 55°C by an adaptive control algorithm in the microprocessor of the RF generator 17.
  • the optimum settings for the RF generator 17 as set forth above can be easily programmed into the RF generator.
  • the RF generator 17 in operating with these optimized settings will supply the necessary power to reach the desired temperature under the control of an appropriate algorithm in the computer in the RF generator 17.
  • the algorithm requires that the power delivered by the RF generator 17 be adequate to arrive at the desired temperature within a predetermined period of time. For example, as shown in Fig. 2, it may be required to reach the desired temperature of 55°C within a period of two minutes.
  • energy delivered by the RF generator 17 can be in the vicinity of 2 to 2.3 watts per electrode, and an electrode with 6 millimeters or less being exposed in the tissue of the insulating sleeve 44, depending upon the size of the prostate with the higher wattage being utilized for the larger prostates.
  • the RF energy delivered is progressively increased to reach the desired temperature without causing an undue rise in the temperature at the needle which could result in desiccation of the tissue around the needle, causing significant resistance to the flow of current and inter ⁇ fering with the formation of the optimal thermal lesion in accordance with the present invention.
  • the algorithm can cause automatic increase of the RF energy delivered by increasing the wattage 0.5 watt at each 30-second interval with the increases continuing throughout the entire rise time. If the temperature does not increase as rapidly as required by the algorithm, the computer will cause additional RF energy to be delivered to the electrode.
  • the power supplied by the RF generator 17 typically can vary from 2 to 9 watts per needle, with the supply of power being controlled by the computer and the RF generator 17 to insure that the final temperature is reached within a predetermined rise time without creating undesired desiccation of tissue, which could cause the needle to impede out.
  • RF power is continued to be supplied to the tissue in the prostate during the dwell time by keeping the tissue at the desired final temperature, also without the desiccation of prostatic tissue. It should be appreciated that the foregoing steps which have been set forth in the method have been carried out automatically under the control of the computer in the RF generator 17. After the desired rise and dwell times have elapsed, the application of RF power is automatically terminated.
  • the physician at any time can assume control if desired by touching an appropriate switch on the control panel after which the physician can control the remaining steps manually. Also, at any time the physician can again return to automatic control by touching the appropriate control legend on the control panel of the RF generator 17.
  • the opti ⁇ mized settings discussed above need only be utilized during the first 30 seconds of a transurethral needle ablation procedure, after which an adaptive or LQR control system can be utilized to automate the entire transure- thral needle ablation procedure and to have as its objec tive an optimal 55°C final temperature.
  • the controller in the RF generator 17 adapts itself based on the values of the stated parameters and of the control parameters recorded following the beginning of the transurethral needle ablation procedure on the patient.
  • Such a control algorithm will not force the prostatic tissue to impede out when trying to reach 55°C and will not permit a minimal lesion to be created with a 55°C final temperature.
  • the foregoing considerations have primarily been set forth in connection with operation of the first and second stylets in a monopolar mode in which the RF energy travels between the stylets and the return electrode 18 rather than in a bipolar mode in which the current is concentrat ⁇ ed between the two needle electrodes of the first and second stylets 41 and 42.
  • the current density is dis- tributed equally between the two needle electrodes and the current concentration around them in comparison to current concentration in the monopolar mode is limited. This limits charring of the "heater" portion of the tissue being ablated. , the power required is minimal and the RF lesion will be much larger. Also, the shape of the lesion will be more evenly distributed, and in particular between the two needle electrodes.
  • an RF generator system 100 in accordance with the present invention may comprise an RF energy power source 110, a microprocessor 112, a memory 114 (for example, RAM, ROM, EPROM or EEPROM), a temperature feedback circuit 116, and an impedance feedback circuit 118.
  • a microprocessor 112 for example, RAM, ROM, EPROM or EEPROM
  • a temperature feedback circuit 116 for example, a temperature feedback circuit 116
  • impedance feedback circuit 118 an impedance feedback circuit 118.
  • the specific imple ⁇ mentation of the aforementioned components is well know in the art, and an exemplary implementation is set forth in U.S. Patent 5,484,400, which has been incorporated herein by reference.
  • the microprocessor 112 of the RF generator 100 of the present invention is configured in a manner which is markedly different from that illustrated in U.S. Patent No. 5,484,400.
  • the programming stored in the memory 114 of the RF generator 100 differs markedly from that utilized by the system described in U.S. Patent No. 5,484,400.
  • the microprocessor 112 may be configured to automatically regulate the amount of RF energy provided to the elec- trodes of the stylets 41 and 42 in response to signals received from the temperature and impedance feedback circuits 116 and 118, respectively.
  • the microprocessor 112 when configured such that the RF generator system 100 operates in an "automatic" mode, the microprocessor 112, in one embodiment, may cause the RF power source to deliver power to the electrode of a given channel in the following manner.
  • the microprocessor 112 Upon initiation of the therapy cycle, the microprocessor 112 will prompt the user to input a rise time value (step 200) , a dwell time value (step 201) and a target temperature value (step 202) .
  • the microprocessor 112 will then set the power to be delivered (P x ) to a value appropriate for the selected rise time and target temperature settings (step 203) .
  • the initial power P x will be set to 1.5 watts.
  • the microprocessor 112 will cause the RF power source to provide, for example, 3.0 watts of power at a frequency of 460 kHz to the electrode (step 204) .
  • the microprocessor 112 will then monitor the temperature and impedance of the tissue surrounding the electrode, via the temperature and impedance feedback circuits 116 and 118, respectively.
  • the microprocessor 112 will cause the RF power source 110 to increase the amount of power supplied to the electrode by 0.5 watts (step 211) , at each 30 second interval, until the temperature of the tissue surrounding the electrode reaches the selected target temperature of, for example, between 45°C and 70°C with the default value being 55°C (step 206) .
  • the microprocessor 112 will not step up the power delivered by the RF power source 110 at the next interval. Further, if the micro ⁇ processor 112 determines that the impedance of the tissue surrounding the electrode is rising at a rate of more than 25 ohms per 0.1 second interval (step 210), the micropro cessor 112 will cause the RF power source 110 to reduce the amount of power delivered to the electrode by, for example, 0.5 watts (step 212). While the time provided for raising the temperature of the tissue surrounding the electrode to the target temperature is programmable, it is presently preferred that this "rise time" period have a duration of between 2.0 and 7.0 minutes with 4.0 minutes being the default value.
  • the micro ⁇ processor will maintain the amount of power delivered by the RF power source 110 at a constant level for a program- mably selectable period of time (step 207) .
  • This period is referred to as the “dwell time” or “hold time” period and, it is presently preferred that the dwell time range from 1.0 to 4.0 minutes with 1.5 minutes being the default value.
  • the microprocessor 112 may regulate the power delivered to a selected electrode in the following manner. As in the case previously discussed, the microprocessor 112 will first prompt the operator of the system to input a rise time value (step 300) , a dwell (or hold) time value
  • the temperature profile for a given channel is established by (1) deter ⁇ mining the temperature of the tissue adjacent an eiec- trode, e.g., via the temperature sensor located at the distal end of the insulating sleeve of the electrode; (2) setting the profile start temperature (T 0 ) to a value 2°C higher than the tissue temperature; (3) plotting a curve between the start temperature value T 0 and the target temperature (or final temperature) value T f over the entered rise time period; and (4) setting the temperature for the dwell time period to the entered target tempera ⁇ ture value.
  • the microprocessor will set the power to be delivered (P : ) to an initial value, for example, 1.5 watts (step 304) , and the microprocessor will cause the RF power source 110 to commence the delivery of power to the electrode (step 305) .
  • the microprocessor 112, thereafter, will continuously adjust the amount of power provided by the RF power source 110 to the electrode, such that the temperature of the tissue in the vicinity of the electrode is elevated and maintained substantially as defined by the temperature profile (step 306) .
  • the following methodology is utilized to maintain the tissue temperature elevation in accordance with the temperature profile.
  • the power delivered by the RF power supply will be increased linearly at a rate of 0.5 watts per minute. If the profile temperature T P exceeds the tissue temperature T tis by 3°C or less (i.e., T p -T tis ⁇ 3°C) , the power delivered by the RF power supply will be in ⁇ creased at a rate of (T p -T tis /3) (0.5) watts per second.
  • tissue temperature T tls exceeds the desired profile temperature T p by 3°C or less (i.e., T tia -T P ⁇ 3°C)
  • the power delivered by the RF power source will be decreased at a rate of (T tis -T p /3) (0.2) watts per second
  • the tissue temperature T tis exceeds the desired profile temper- ature T p by more than 3°C (i.e., T tis -T p > 3°C)
  • the power delivered by the RF power supply will be reduced by M, and held at that level for 6.0 seconds. Thereafter, the power regulation will continue as described above.
  • the microprocessor 112 will terminate the procedure (step 307) .
  • the microprocessor 112 determines that the impedance of the tissue in the area of the electrode is increasing too quickly, for example, at a rate in excess of 25 ohms per 0.1 second or, alternatively, if the microprocessor 112 determines that the impedance of the tissue is more than, for example, 25 ohms greater than an average running impedance of the tissue (step 310) , the microprocessor 112 will cause the RF power source 110 to reduce the amount of power delivered to the electrode by a selected amount, for example, to the minimum operating power (step 308) .
  • the power will be held at that level for a selected period, for example, 0.5 seconds, and thereafter, at selected intervals, e.g., 1.0, 2.0 or 5.0 second intervals, the microprocessor will cause the power delivery to be restored to 25% of the power delivered at the impedance rise point (P m ) , 50% of the power delivered at the impedance rise point P m , and 75% of the power delivered at the impedance rise point, if that is possible without exceeding the impedance rate limit and without exceeding the desired temperature value, as determined from the temperature profile (step 309) .
  • the power delivery will then be continuously adjusted to maintain the temperature of the tissue in accordance with the temperature profile (step 306), as described above. If at any point within the power stepping up procedure the impedance again rises too quickly, the procedure described above will be repeated.
  • the RF power may be delivered via two separate and distinct channels and in either a bi-polar or mono-polar mode, as described in U.S. Patent No. 5,484,400.
  • the power delivered to each channel may be independently controlled by the microprocessor 112 in the manner set forth above.
  • the temperature of the patient's urethra exceeds a predetermined temperature, for example, a temperature exceeding 47°C, the procedure will be terminated, and the delivery power to the electrode(s) will be terminated. Further, if at any time during a procedure the impedance of the tissue surrounding an electrode exceeds, for example, 540 ohms, the delivery of RF energy to that electrode will be terminated.

Abstract

Systèmes et procédés perfectionnés permettant de provoquer des lésions dans des tissus humains par ablation radiofréquence. Un système générateur d'énergie R.F. est utilisé pour réguler automatiquement un niveau d'énergie R.F. fourni à une électrode déployée dans la zone de tissus à soumettre à une ablation. Cette énergie R.F. est appliquée de telle façon que la température du tissu dans ladite zone est augmentée de manière régulée jusqu'à une valeur cible sur une première période sélectionnée, puis maintenue à cette valeur cible pendant une deuxième période. Une formation de lésion maximale peut être obtenue au moyen des systèmes et des procédés selon la présente invention.
PCT/US1997/007311 1996-05-01 1997-04-30 Systemes et procedes d'optimisation de l'apport en energie radiofrequence pour la formation de lesions dans des tissus humains WO1997040882A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU31168/97A AU3116897A (en) 1996-05-01 1997-04-30 Systems and methods for optimizing the delivery of radio frequency energy for lesion formation within human tissue

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US64152896A 1996-05-01 1996-05-01
US08/641,528 1996-05-01

Publications (3)

Publication Number Publication Date
WO1997040882A2 true WO1997040882A2 (fr) 1997-11-06
WO1997040882A3 WO1997040882A3 (fr) 1997-12-18
WO1997040882A9 WO1997040882A9 (fr) 1998-02-12

Family

ID=24572768

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/007311 WO1997040882A2 (fr) 1996-05-01 1997-04-30 Systemes et procedes d'optimisation de l'apport en energie radiofrequence pour la formation de lesions dans des tissus humains

Country Status (3)

Country Link
AU (1) AU3116897A (fr)
TW (1) TW351673B (fr)
WO (1) WO1997040882A2 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6047215A (en) * 1998-03-06 2000-04-04 Sonique Surgical Systems, Inc. Method and apparatus for electromagnetically assisted liposuction
WO2006069313A1 (fr) * 2004-12-20 2006-06-29 Vnus Medical Technologies, Inc. Systemes et procedes de traitement d'une structure anatomique creuse
US9750560B2 (en) 2010-10-25 2017-09-05 Medtronic Ardian Luxembourg S.A.R.L. Devices, systems and methods for evaluation and feedback of neuromodulation treatment
US10433902B2 (en) 2013-10-23 2019-10-08 Medtronic Ardian Luxembourg S.A.R.L. Current control methods and systems
US10610292B2 (en) 2014-04-25 2020-04-07 Medtronic Ardian Luxembourg S.A.R.L. Devices, systems, and methods for monitoring and/or controlling deployment of a neuromodulation element within a body lumen and related technology
US10722288B2 (en) 2006-06-28 2020-07-28 Medtronic Ardian Luxembourg S.A.R.L. Devices for thermally-induced renal neuromodulation
CN113631113A (zh) * 2019-03-28 2021-11-09 坎德拉公司 用于治疗组织的设备和方法
SE2150579A1 (en) * 2021-05-06 2022-11-07 Curative Cancer Treat By Heat Cctbh Ab Tumor denaturization control in curative cancer treatment

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4950267A (en) * 1987-11-27 1990-08-21 Olympus Optical Co., Ltd. Laser beam treatment device for an endoscope
US5370675A (en) * 1992-08-12 1994-12-06 Vidamed, Inc. Medical probe device and method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4950267A (en) * 1987-11-27 1990-08-21 Olympus Optical Co., Ltd. Laser beam treatment device for an endoscope
US5370675A (en) * 1992-08-12 1994-12-06 Vidamed, Inc. Medical probe device and method

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6047215A (en) * 1998-03-06 2000-04-04 Sonique Surgical Systems, Inc. Method and apparatus for electromagnetically assisted liposuction
WO2006069313A1 (fr) * 2004-12-20 2006-06-29 Vnus Medical Technologies, Inc. Systemes et procedes de traitement d'une structure anatomique creuse
US7842076B2 (en) 2004-12-20 2010-11-30 Tyco Healthcare Group, Lp Systems and methods for treating a hollow anatomical structure
US10722288B2 (en) 2006-06-28 2020-07-28 Medtronic Ardian Luxembourg S.A.R.L. Devices for thermally-induced renal neuromodulation
US11801085B2 (en) 2006-06-28 2023-10-31 Medtronic Ireland Manufacturing Unlimited Company Devices for thermally-induced renal neuromodulation
US9750560B2 (en) 2010-10-25 2017-09-05 Medtronic Ardian Luxembourg S.A.R.L. Devices, systems and methods for evaluation and feedback of neuromodulation treatment
US10179020B2 (en) 2010-10-25 2019-01-15 Medtronic Ardian Luxembourg S.A.R.L. Devices, systems and methods for evaluation and feedback of neuromodulation treatment
US11006999B2 (en) 2010-10-25 2021-05-18 Medtronic Ardian Luxembourg S.A.R.L. Devices, systems and methods for evaluation and feedback of neuromodulation treatment
US10433902B2 (en) 2013-10-23 2019-10-08 Medtronic Ardian Luxembourg S.A.R.L. Current control methods and systems
US10610292B2 (en) 2014-04-25 2020-04-07 Medtronic Ardian Luxembourg S.A.R.L. Devices, systems, and methods for monitoring and/or controlling deployment of a neuromodulation element within a body lumen and related technology
CN113631113A (zh) * 2019-03-28 2021-11-09 坎德拉公司 用于治疗组织的设备和方法
SE2150579A1 (en) * 2021-05-06 2022-11-07 Curative Cancer Treat By Heat Cctbh Ab Tumor denaturization control in curative cancer treatment

Also Published As

Publication number Publication date
WO1997040882A3 (fr) 1997-12-18
AU3116897A (en) 1997-11-19
TW351673B (en) 1999-02-01

Similar Documents

Publication Publication Date Title
US7131445B2 (en) Electrosurgical method and apparatus
EP1862137B1 (fr) Système de contrôle de la vitesse de chauffage d'un tissu avant une vaporisation cellulaire
US7377918B2 (en) Electrosurgical method and apparatus
US6818000B2 (en) Electrode arrangement for electrothermal treatment of human or animal bodies
US7094215B2 (en) Systems and methods for electrosurgical tissue contraction
JP5322266B2 (ja) マイクロ波適用のための反射電力モニタリング
CA2303187C (fr) Systeme de chauffage des tissus solides et son utilisation
JP4484256B2 (ja) 電気手術用のジェネレータ及びシステム
US5843026A (en) BPH ablation method and apparatus
US6280441B1 (en) Apparatus and method for RF lesioning
WO2004056277A1 (fr) Procede et appareil d'electrochirurgie
EP1018994B1 (fr) Systemes et methodes pour retraction tissulaire electrochirurgicale
US6512956B2 (en) Method of constructing a microwave antenna
JP2001514557A (ja) 組織切除のための方法および装置
JP2006520622A (ja) 医療アブレーションのためのマイクロ波アンテナ
WO1997040882A2 (fr) Systemes et procedes d'optimisation de l'apport en energie radiofrequence pour la formation de lesions dans des tissus humains
WO1997040882A9 (fr) Systemes et procedes d'optimisation de l'apport en energie radiofrequence pour la formation de lesions dans des tissus humains
JP6570813B2 (ja) 双極アブレーションのための適応電極
US5928225A (en) Device for the treatment of benign prostatic hyperplasia
Smith et al. Radiofrequency electrosurgery
Desinger et al. High-frequency current application in bipolar technique for interstitial thermotherapy (HF-ITT)
WO2000056229A1 (fr) Systemes et procedes de contraction tissulaire electrochirurgicale

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AU CA CN JP KR

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

AK Designated states

Kind code of ref document: A3

Designated state(s): AU CA CN JP KR

AL Designated countries for regional patents

Kind code of ref document: A3

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

COP Corrected version of pamphlet

Free format text: PAGES 4/5 AND 5/5, DRAWINGS, REPLACED BY NEW PAGES BEARING THE SAME NUMBER

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
NENP Non-entry into the national phase in:

Ref country code: JP

Ref document number: 97539207

Format of ref document f/p: F

NENP Non-entry into the national phase in:

Ref country code: CA

122 Ep: pct application non-entry in european phase