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

1. An ablation device, comprising:

a feedline including an inner conductor having a distal end and a first diameter, 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 and a second diameter different than the first diameter;

a dielectric layer coaxially disposed around a first portion of the outer conductor;

a first balun disposed over the first portion of the outer conductor and positioned so that a distal end of the first balun is located at a first distance from the proximal end of the elongated electrically-conductive member, the first balun including an electrically-conductive layer coaxially disposed around a proximal portion of the dielectric layer, wherein the dielectric layer extends distally beyond a distal-most end of the inner conductor; and

a second balun disposed over a second portion of the outer conductor and positioned so that a distal end of the second balun is located at a second distance from the proximal end of the elongated electrically-conductive member.

2. The ablation device of claim 1 , wherein the first balun is operably associated with a first operating frequency.

3. The ablation device of claim 2 , wherein the first balun 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 is operably associated with a 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 5 , further comprising a third balun structure, wherein the third balun is operably associated with a third operating frequency.

8. 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.

9. 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.

10. The ablation device of claim 9 , wherein the lumen is configured to contain the elongated electrically-conductive member and the first and second baluns therein.

11. The ablation device of claim 10 , further comprising a coolant chamber defined between the substantially tubular member and the elongated electrically-conductive member and the first and second baluns.

12. The ablation device of claim 11 , further comprising an outer dielectric layer disposed over at least a portion of the elongated electrically-conductive member and the first and second baluns.

13. The ablation device of claim 1 , wherein the dielectric layer extends distally beyond the distal-most end of the electrically-conductive layer to direct current into the first balun.

14. 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, the inner conductor having a first diameter;

an elongated electrically-conductive member disposed at a distal end of the inner conductor and having a second diameter different than the first diameter;

a dielectric layer coaxially disposed around a distal portion of the outer conductor;

a first balun operably associated with a first operating frequency, the first balun including an electrically-conductive layer coaxially disposed around a proximal portion of the dielectric layer, wherein the dielectric layer extends distally beyond a distal-most end of the inner conductor; and

a second balun operably associated with a second operating frequency, wherein the second balun is electrically coupled to the outer conductor.

15. The system of claim 14 , 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.

16. The system of claim 15 , further comprising a coolant supply system in fluid communication with the lumen.

17. The ablation device of claim 14 , wherein the dielectric layer extends distally beyond the distal-most end of the electrically-conductive layer to direct current into the first balun.

18. An ablation device, comprising:

a feedline including an inner conductor having a distal end and a first diameter, 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 and a second diameter different than the first diameter;

a dielectric layer coaxially disposed around a first portion of the outer conductor;

a first balun disposed over the first portion of the outer conductor and positioned so that a distal end of the first balun is located at a first distance from the proximal end of the elongated electrically-conductive member, the first balun including an electrically-conductive layer coaxially disposed around a proximal portion of the dielectric layer, wherein the dielectric layer extends distally beyond a distal-most end of the inner conductor, and wherein a proximal end of the electrically-conductive layer is adapted to allow for connection to the outer conductor; and

a second balun disposed over a second portion of the outer conductor and positioned so that a distal end of the second balun is located at a second distance from the proximal end of the elongated electrically-conductive member.