Electrical discharge devices and techniques for medical procedures
View Patent ↗A medical instrument coupled to first and second energy means and a computer controller for the controlled volumetric removal of thin tissue layers. The system provides a source for introducing a gas to controllably form and capture transient gas volumes in a microchannel structure at the working surface of the instrument that interfaces with a targeted tissue site. Each of the microchannel features of the working surface carries an electrode element coupled to the electrical source. The energy may be applied to the targeted site in either of two modes of operation, depending in part on voltage and repetition rate of energy delivery. In one mode of energy application, electrical potential is selected to cause an intense electrical arc across the transient ionized gas volumes to cause an energy-tissue interaction characterized by tissue vaporization. In another preferred mode of energy delivery, the system applies selected levels of energy to the targeted site by means of an energetic plasma at the instrument working surface to cause molecular volatilization of surface macromolecules thus resulting in material removal. Both modes of operation limit collateral thermal damage to tissue volumes adjacent to the targeted site. Another preferred embodiment provides and an ultrasound source or other vibrational source coupled to the working end to cause cavitation in fluid about the working end.
1. A method for application of energy to a targeted site on a body structure, comprising the steps of:
(a) positioning an instrument working surface in proximity to the targeted site, wherein the working surface carries at least one media entrance channel and at least one electrode;
(b) providing at least one bubble of a selected gas between a termination of the channel and the targeted site, wherein each bubble defines a selected dimension between the electrode in end and the targeted site;
(c) applying vibrational energy to said working surface; and
(d) applying electrical energy from said electrode to said targeted site across said at least one bubble wherein said vibrational energy alters said selected dimension of said at least one bubble to thereby reduce the voltage required for said application of energy thereacross.
2. The method of claim 1 wherein said vibrational energy comprises ultrasonic vibration.
3. The method of claim 1 wherein said vibrational energy reduces said selected dimension of said at least one bubble.
4. The method of claim 1 wherein step (b) provides said at least one bubble in a fluid environment
5. The method of claim 1 wherein said selected gas is a neutral gas and wherein step (d) further comprises the step of ionizing the said gas volume from a source independent of said electrode surfaces.
6. The method of claim 5 wherein the ionizing step is caused by ionization means selected from the class of photoionization means and field ionization means.
7. The method of claim 1 wherein in step (b) provides the selected gas through said at least one channel.
8. The method of claim 1 wherein in step (d) the energy application is of sufficient intensity to cause volumetric material removal.