Method for electrosurgery with enhanced electric field and minimal tissue damage

Abstract

The present invention is directed towards an electrosurgical cutting system. The system comprises an electrically conductive blade, having first and second blade surfaces. First and second insulators are affixed to the first and second blade surfaces, respectively. A blade edge, a region between the first and second blade surfaces, has an edge radius of curvature, which preferably is small. A source of pulsed electrical energy coupled to the electrically conductive blade provides a substantially uniform and highly enhanced electric field along a cutting portion of the blade edge. The system can also be comprised of a wire electrode. Despite the fact that its field is strongly enhanced around the apex, a uniform vapor cavity is formed and then ionized using an appropriately designed burst of pulses, preferably of alternating polarity.

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         28 : A method for cutting of biological tissue along a cutting zone of an electrode immersed in a liquid medium, the method comprising:
 a) delivering a burst of electrical pulses to said electrode to form a vapor layer of said liquid medium surrounding the cutting zone of the electrode, wherein a first vapor cavity forms in a high electric field region of said electrode, and wherein said electrical pulses do not ionize said first vapor cavity, and wherein said burst of electrical pulses vaporizes said liquid medium in regions of lower electric field wherein said vapor layer is formed along the whole cutting zone before said first vapor cavity collapses; and   b) ionizing said vapor layer resulting in plasma-mediated discharge into the biological tissue contacting said vapor layer.   
     
     
         29 : The method of  claim 28 , wherein a total duration of said burst of pulses is less than 10 ms, whereby thermal damage to said tissue is reduced. 
     
     
         30 : The method of  claim 29 , wherein said total duration of said burst of pulses is less than 1 ms. 
     
     
         31 : The method of  claim 30 , wherein said total duration of said burst of pulses is less than 0.1 ms. 
     
     
         32 : The method of  claim 28 , wherein said pulses have a pulse duration between 10 ns and 10 μs. 
     
     
         33 : The method of  claim 28 , wherein each pulse in said burst of pulses has opposite polarity than the previous pulse. 
     
     
         34 : The method of  claim 28 , further comprising repetitively performing said delivering a burst of electrical pulses, wherein any two time-adjacent bursts are separated by an interval greater than 1 ms in duration.