Method for treating tissue with a wet electrode and apparatus for using same

Abstract

A method for treating tissue of a mammalian body in which the conductivity of the tissue is characterized. The amount of a conductive liquid to supply to the tissue is determined as a function of the conductivity of the tissue and injected into the tissue over an interval of time. Electromagnetic energy is supplied to the tissue to form a lesion in the tissue. A computer-readable memory and a radio frequency generator and controller utilizing such method are further provided.

1 . A method for treating tissue of a mammalian body comprising the steps of determining a volume of an electrode that will enhance lesion foflllation when an electrode having such volume is placed in the tissue and energy is supplied thereto, injecting an amount of a conductive liquid approximating the volume into the tissue to create a wet electrode and  5  supplying radio frequency energy to the wet electrode to ablate the tissue.  
   
   
       2 . The method of  claim 1  wherein the amount of the conductive liquid equals the volume.  
   
   
       3 . The method of  claim 1  wherein the energy is radio frequency energy.  
   
   
       4 . The method of  claim 3  wherein the injecting step includes injecting the conductive liquid through a stylet having a radio frequency electrode.  
   
   
       5 . A method for treating tissue of a mammalian body comprising the steps of characterizing the conductivity of the tissue, deteflllining the amount of radio frequency energy to supply to the tissue for fofllling a lesion in the tissue as a function of the conductivity of the tissue and supplying the radio frequency energy to the tissue.  
   
   
       6 . The method of  claim 5  further comprising the steps of deteflllining an “V” amount of a conductive liquid to supply to the tissue as a function of the conductivity of the tissue and injecting the amount of conductive liquid into the tissue.  
   
   
       7 . A method for treating tissue of a prostate of a human male with a stylet having a needle electrode and a layer of insulating material extending around the needle electrode but exposing a distal portion of the needle electrode and a temperature sensor carried by the stylet comprising the steps of introducing the stylet into the tissue of the prostate, characterizing the conductivity of the tissue, determining an amount of a conductive liquid to supply to the tissue as a function of the conductivity of the tissue, injecting the amount of conductive liquid through the stylet into the tissue and supplying radio frequency energy to the conductive electrode by means of the needle electrode to form a lesion in the tissue.  
   
   
       8 . The method of  claim 7  wherein the characterizing step includes the steps of supplying radio frequency power to the tissue by means of the needle electrode at a first power level and for a first length of time and thereafter measuring the temperature of the tissue with the temperature sensor and supplying radio frequency power to the tissue by means of the needle electrode at a second power level and for a second length of time and thereafter measuring the temperature of the tissue with the temperature sensor.  
   
   
       9 . A computer-readable memory for use with a radio frequency generator and controller and a reservoir of a conductive liquid coupled to the controller, the memory containing a computer program for causing the controller to treat tissue of a mammalian body by determining a volume of an electrode that will enhance lesion formation when an electrode having such volume is placed in the tissue and radio frequency energy is supplied thereto, signaling the reservoir to inject an amount of a conductive liquid approximating the volume into the tissue to create a wet electrode and supplying radio frequency energy to the wet electrode to ablate the tissue.  
   
   
       10 . A computer-readable memory for use with a radio frequency generator and controller, the memory containing a computer program for causing the controller to treat tissue of a mammalian body by characterizing the conductivity of the tissue, determining the amount of radio frequency energy to supply to the tissue for forming a lesion in the tissue as a function of the conductivity of the tissue and supplying the radio frequency energy to the tissue.  
   
   
       11 . A radio frequency generator and controller for use with a stylet having proximal and distal extremities and a lumen extending longitudinally from the proximal extremity to the distal extremity and a temperature sensor carried by the distal extremity comprising a computer-readable memory containing a computer program for causing the controller to treat tissue of a mammalian body by characterizing the conductivity of the tissue, determining the amount of a conductive liquid to supply through the lumen of the stylet for forming a wet electrode in the tissue as a function of the conductivity of the tissue and supplying radio frequency energy to the wet electrode, and a central processing unit coupled to the memory for executing the program in the memory.  
   
   
       12 . The controller of  claim 11  wherein the computer program further causes the controller to determine the amount of radio frequency energy to supply to the tissue for forming a lesion in the tissue as a function of the conductivity of the tissue.  
   
   
       13 . The controller of  claim 11  for use with a reservoir of a conductive liquid coupled to the proximal extremity of the stylet in communication with the lumen wherein the computer program further causes the controller to signal the reservoir to inject the amount of the conductive liquid into the tissue.