Electrosurgical instrument and method of use

Abstract

Embodiments of the invention provide an electrosurgical jaw structure comprising first and second opposing jaws one or both of which include 3D variable resistance bodies. The jaw structure can be part of the working end of a surgical instrument. In one embodiment, the jaws can comprise first and second energy-delivery jaw surfaces having first and second 3D variable resistance bodies, with the jaw surface configured to be coupled to an Rf source. The 3D variable resistance bodies can define different temperature-resistance curves. The 3D bodies can be configured to control ohmic heating of tissue by modulating the delivery of Rf energy to tissue. Jaw structures having the 3D bodies can be used to engage and produce high strength tissue welds in targeted tissue including tissue volumes having varying tissue types. Such jaw structures can be configured to simultaneously apply different energy levels to each tissue type within the tissue volume.

1 . An electrosurgical jaw structure for applying Rf energy to tissue, the structure comprising:
 first and second jaws defining first and second tissue engagement surfaces, respectively, at least one of the engagement surfaces including opposing polarity conductor portions, the conductor portions configured to be coupled to an Rf energy source; and   a polymeric matrix portion positioned within at least one tissue engagement surface, the matrix configured to modulate at least one parameter of Rf energy application, the at least one parameter including at least one of voltage, current or impedance.   
   
   
       2 . A jaw structure of  claim 1 , wherein the matrix is configured to modulate Rf energy application from a conductor portion in the engagement surface to adjacent tissue. 
   
   
       3 . A jaw structure for applying energy to tissue, the structure comprising:
 first and second jaw bodies extending along an axis and defining first and second tissue-engaging surfaces, respectively; at least one jaw body comprising a three dimensional matrix of a temperature-responsive variable impedance material for impedance matching with engaged tissue, the matrix configured to modulate current density in the engaged tissue; and   opposing polarity conductor regions in the tissue-engaging surfaces, the regions configured to be coupled to a voltage source for providing contemporaneous current flow paths through engaged tissue.   
   
   
       4 . The jaw structure of  claim 3 , wherein the first and second jaw bodies comprise first and second temperature-responsive variable impedance matrices, respectively, the first matrix configured to be coupled to the voltage source in a first circuit and the second matrix configured to be coupled to the voltage source in a second circuit. 
   
   
       5 . The jaw structure of  claim 3 , wherein the first circuit is a series circuit and the second circuit is a parallel circuit. 
   
   
       6 . An electrosurgical jaw structure for controlled application of energy to tissue, the structure comprising:
 first and second jaw bodies defining first and second tissue-engaging surfaces, respectively, at least one of the jaw bodies comprising a three-dimensional (3D) matrix of a temperature-responsive variable impedance material for impedance matching with engaged tissue to thereby provide contemporaneous current flow paths through engaged tissue, the 3D matrix positioned within at least one of the jaw bodies and configured to modulate current density in the engaged tissue; and   opposing polarity conductor regions positioned on at least one of the tissue-engaging surfaces, the regions configured to be coupled to a voltage source.   
   
   
       7 . The electrosurgical jaw structure of  claim 6 , wherein the matrix defines spaced apart current flow paths (a) between the opposing polarity conductor regions proximate a tissue-engaging surface, and (b) between the opposing polarity conductor regions at an interior of at least one jaw body. 
   
   
       8 . The electrosurgical jaw structure of  claim 6 , wherein a portion of the first jaw body comprises a first 3D matrix of a temperature-responsive variable impedance material and a portion of the second jaw body comprises a second 3D matrix of a temperature-responsive variable impedance material. 
   
   
       9 . The electrosurgical jaw structure of  claim 8 , wherein the first and second 3D matrices have different impedance characteristics. 
   
   
       10 . The electrosurgical jaw structure of  claim 9 , wherein the different impedance characteristics include at least one of a baseline impedance or a temperature impedance response. 
   
   
       11 . The electrosurgical jaw structure of  claim 8 , wherein the first and second matrices are coupled in parallel circuits with the voltage source. 
   
   
       12 . The electrosurgical jaw structure of  claim 6 , wherein the matrix defines a positive temperature coefficient of impedance. 
   
   
       13 . The electrosurgical jaw structure of  claim 6 , wherein the matrix defines a negative temperature coefficient of impedance. 
   
   
       14 . An electrosurgical jaw structure comprising:
 first and second jaw bodies defining first and second energy-delivery surfaces, at least one jaw body comprising first and second opposing polarity portions; and   a temperature-responsive variable impedance body positioned intermediate the first and second opposing polarity portions.   
   
   
       15 . The electrosurgical instrument of  claim 14 , wherein a portion of the variable impedance body is exposed on one of the first or the second energy delivery surfaces. 
   
   
       16 . An electrosurgical jaw structure for application of Rf energy to tissue, the structure comprising:
 first and second tissue engagement means defining first and second tissue engagement surfaces, respectively;   opposing polarity conductor means coupled to the tissue engagement means, the conductor means configured to be coupled to an Rf source means; and   an Rf modulating means portion coupled to at least one tissue engagement surface, the Rf modulating means configured to modulate at least one parameter of Rf energy application from a conductor means portion in an engagement surface to the adjacent tissue, the parameter including at least one of voltage, current or impedance.   
   
   
       17 . A method of applying Rf energy to tissue, the method comprising:
 engaging tissue with an engagement surface including a three dimensional (3D) body of a temperature-responsive variable impedance material and opposing polarity conductor regions, the regions operatively coupled to an Rf source;   initiating current flow within the engaged tissue and the 3D body to cause ohmic tissue heating;   utilizing the ohmically heated tissue to conductively heat adjacent regions of the 3D body; and   utilizing an impedance response of the heated 3D body to modulate current flow between paths in tissue and paths in the 3D body.   
   
   
       18 . The method of  claim 19 , wherein the 3D body varies its impedance to substantially match impedance of adjacent tissue to modulate the current flow between paths in tissue and paths in the 3D body. 
   
   
       19 . The method of  claim 17 , wherein the variable impedance material is positioned intermediate the conductor regions. 
   
   
       20 . The method of  claim 17 , further comprising:
 utilizing the 3D body to modulate current to control at least one of tissue temperature; peak tissue temperature or tissue heating.   
   
   
       21 . The method of  claim 17 , wherein the current paths in the 3D body include paths in surface regions of the 3D body and paths in interior regions of the 3D body. 
   
   
       22 . A method of delivery Rf energy to tissue, the method comprising:
 engaging a tissue volume with an engagement surface including a three dimensional (3D) body of a temperature-responsive variable impedance material, wherein the tissue volume includes a plurality of tissue types;   initiating current flow within the engaged tissue volume and the 3D body to cause ohmic tissue heating;   utilizing the ohmically heated tissue to conductively heat adjacent regions of the 3D body; and   utilizing the 3D body to modulate energy delivery to the engaged tissue volume responsive to an impedance of at least one tissue type of the plurality of tissue types.   
   
   
       23 . The method of  claim 22 , wherein the impedance includes a first impedance of a first tissue type and a second impedance of a second tissue type. 
   
   
       24 . The method of  claim 22 , wherein the 3D body is used to continuously modulate energy delivery to the at least one tissue type. 
   
   
       25 . The method of  claim 22 , wherein the 3D body is used to modulate energy delivery to the at least one tissue type as a physical property of the least one tissue type changes. 
   
   
       26 . The method of  claim 25 , wherein the physical property includes at least one of a hydration level, impedance, conductivity or geometry. 
   
   
       27 . The method of  claim 22 , wherein the 3D body is used to modulate at least one of current or current density of the at least one tissue type.