Ablation devices with dual operating frequencies, systems including same, and methods of adjusting ablation volume using same

Abstract

An ablation device includes a feedline including an inner conductor having a distal end, an outer conductor coaxially disposed around the inner conductor, and a dielectric material disposed therebetween, an elongated electrically-conductive member longitudinally disposed at the distal end of the inner conductor and having a proximal end, a first balun structure disposed over a first portion of the outer conductor and positioned so that a distal end of the first balun structure is located at a first distance from the proximal end of the electrically-conductive member and a second balun structure disposed over a second portion of the outer conductor and positioned so that a distal end of the second balun structure is located at a second distance from the proximal end of the electrically-conductive member.

What is claimed is: 
     
         1 . An ablation device, comprising:
 a feedline including an inner conductor having a distal end, an outer conductor coaxially disposed around the inner conductor, and a dielectric material disposed therebetween;   an elongated electrically-conductive member longitudinally-disposed at the distal end of the inner conductor and having a proximal end;   a first balun structure disposed over a first portion of the outer conductor and positioned so that a distal end of the first balun structure is located at a first distance from the proximal end of the electrically-conductive member; and   a second balun structure disposed over a second portion of the outer conductor and positioned so that a distal end of the second balun structure is located at a second distance from the proximal end of the electrically-conductive member.   
     
     
         2 . The ablation device of  claim 1 , wherein the first balun structure is operably associated with the first operating frequency. 
     
     
         3 . The ablation device of  claim 2 , wherein the first balun structure is a quarter-wave sleeve balun. 
     
     
         4 . The ablation device of  claim 2 , wherein the first operating frequency is about 915 MHz. 
     
     
         5 . The ablation device of  claim 1 , wherein the second balun structure is operably associated with the second operating frequency. 
     
     
         6 . The ablation device of  claim 5 , wherein the second operating frequency is about 2.45 GHz. 
     
     
         7 . The ablation device of  claim 1 , wherein a portion of the inner conductor and the dielectric material of the feedline extend beyond the outer conductor at a distal end of the feedline. 
     
     
         8 . The ablation device of  claim 1 , further comprising a sheath including a substantially tubular member defining a lumen therein, wherein the lumen is configured to contain at least a portion of the ablation device therein. 
     
     
         9 . The ablation device of  claim 8 , wherein the lumen is configured to contain the elongated electrically-conductive member and the first and second balun structures therein. 
     
     
         10 . The ablation device of  claim 9 , further comprising a coolant chamber defined between the tubular member and the elongated electrically-conductive member and the first and second balun structures. 
     
     
         11 . The ablation device of  claim 10 , further comprising an outer dielectric layer disposed over at least a portion of the elongated electrically-conductive member and the first and second balun structures. 
     
     
         12 . The ablation device of  claim 1 , further comprising a third balun structure, wherein the third balun structure is operably associated with a third operating frequency. 
     
     
         13 . A system, comprising:
 a generator assembly; and   an ablation device operably associated with the generator assembly, the ablation device including:
 a feedline having an inner conductor, an outer conductor coaxially-disposed around the inner conductor, and a dielectric material disposed therebetween; 
 a first balun structure operably associated with a first operating frequency, wherein the first balun structure is electrically coupled to the outer conductor; and 
 a second balun structure operably associated with a second operating frequency, wherein the second balun structure is electrically coupled to the outer conductor. 
   
     
     
         14 . The system of  claim 13 , wherein the ablation device further includes a sheath including a substantially tubular member defining a lumen therein, wherein the lumen is configured to contain at least a portion of the ablation device therein. 
     
     
         15 . The system of  claim 14 , further comprising a coolant supply system in fluid communication with the lumen. 
     
     
         16 . A method of adjusting ablation volume, comprising the steps of:
 position an ablation device in tissue, the ablation device capable of operating at a first operating frequency and a second operating frequency, the ablation device including an antenna assembly configured with a first balun operably associated with the first operating frequency and a second balun operably associated with the second operating frequency;   transmitting energy from an energy source through the antenna assembly to tissue at the first operating frequency; and   transmitting energy from the energy source through the antenna assembly to tissue at the second operating frequency.   
     
     
         17 . The method of adjusting ablation volume of  claim 16 , further comprising the step of:
 adjusting the ablation field radiating about at least a portion of the ablation device by selectively transmitting energy through the antenna assembly to tissue at the first operating frequency and the second operating frequency.   
     
     
         18 . The method of adjusting ablation volume of  claim 16 , wherein the first operating frequency is about 914 MHz. 
     
     
         19 . The method of adjusting ablation volume of  claim 16 , wherein the second operating frequency is about 2.45 GHz. 
     
     
         20 . The method of adjusting ablation volume of  claim 16 , wherein the second operating frequency is about 5.8 GHz.