Tissue ablation systems and method
Tissue is treated using a radiofrequency power supply connected to an applicator having a chamber filled with an electrically non-conductive gas surrounded by a thin dielectric wall. A radiofrequency voltage is applied at a level sufficient to ionize the gas into a plasma and to capacitively couple the ionized plasma with the tissue to deliver radiofrequency current to ablate or otherwise treat the tissue.
1 . A method of applying energy to tissue, said method comprising:
engaging a dielectric wall against the tissue, the dielectric wall defining a chamber therein;
delivering an electrically non-conductive gas into the chamber;
applying a voltage between a first electrode and a second electrode to initiate ionization of the gas into a plasma completely contained within the chamber and separated from the tissue by the dielectric wall; and
capacitively coupling the plasma across the dielectric wall and into the tissue.
2 . The method of claim 1 , wherein the first electrode is positioned within the chamber.
3 . The method of claim 2 , wherein the second electrode is posited exterior of the chamber.
4 . The method of claim 1 , wherein the step of delivering the electrically non-conductive gas into the chamber includes providing a continuous flow of the gas into the chamber.
5 . The method of claim 4 , wherein the gas is provided at a flow rate of 5 ml/sec. to 30 ml/sec.
6 . The method of claim 1 , wherein the voltage is at least 100 volts.
7 . The method of claim 1 , wherein the dielectric wall is formed of a conformable silicone.
8 . The method of claim 1 , wherein the dielectric wall has a thickness in a range of 0.004 inches to 0.03 inches.
9 . The method of claim 1 , wherein a frame is provided within the chamber.
10 . The method of claim 9 , further comprising:
expanding the frame to open the dielectric wall.
11 . The method of claim 1 , further comprising:
ablating the tissue.
12 . The method of claim 11 , wherein the tissue is ablated to a depth of 1 mm to 5 mm.
13 . The method of claim 1 , wherein the dielectric wall is coupled to an elongate shaft.
14 . The method of claim 13 , wherein the gas flows through the elongate shaft into the chamber.
15 . The method of claim 1 , wherein the gas is argon.
16 . A method of applying energy to tissue, said method comprising:
engaging a dielectric wall against the tissue, the dielectric wall defining a chamber therein;
delivering an electrically non-conductive gas into the chamber;
passing a radiofrequency energy between a first electrode within the chamber and a second electrode exterior of the chamber to initiate ionization of the gas into a plasma completely contained within the chamber and separated from the tissue by the dielectric wall; and
ablating the tissue with the radiofrequency energy.
17 . The method of claim 16 , wherein the tissue is ablated to a depth of 1 mm to 5 mm.
18 . The method of claim 16 , wherein the step of delivering the electrically non-conductive gas into the chamber includes providing a continuous flow of the gas into the chamber.
19 . The method of claim 16 , wherein a frame is provided within the chamber.
20 . The method of claim 19 , further comprising:
expanding the frame to open the dielectric wall.