Helical needle apparatus for creating a virtual electrode used for the ablation of tissue

Abstract

A surgical apparatus for delivering a conductive fluid to a target site for subsequent formation of a virtual electrode to ablate bodily tissue at the target site by applying a current to the delivered conductive fluid. The surgical apparatus includes an elongated device forming a helical needle. The helical needle is configured to engage bodily tissue and is hollow for delivering conductive fluid from a fluid source. Finally, the helical needle terminates in a needle tip. In one preferred embodiment, an electrode is associated with the helical needle for applying a current to conductive fluid delivered from the helical needle. During use, following delivery of conductive fluid, the electrode applies a current to the delivered conductive fluid for creating a virtual electrode. The virtual electrode ablates bodily tissue contacted by the conductive fluid.

1 . A surgical apparatus for delivering conductive fluid to a target site for subsequent formation of a virtual electrode to ablate bodily tissue at the target site by applying a current to the delivered conductive fluid, the apparatus comprising: 
 an elongated device forming a helical needle assembly including a first helical needle configured to engage bodily tissue, the first helical needle being hollow for delivering conductive fluid from a fluid source and forming a needle tip.    
     
     
         2 . The surgical apparatus of  claim 1 , wherein the first helical needle forms an electrode.  
     
     
         3 . The surgical apparatus of  claim 1 , wherein the first helical needle includes a plurality of adjacent coils, and further wherein a pitch between each of the plurality of adjacent coils is variable.  
     
     
         4 . The surgical apparatus of  claim 3 , wherein the pitch decreases proximally along at least a portion of the length of the first helical needle.  
     
     
         5 . The surgical apparatus of  claim 1 , wherein the first helical needle includes a plurality of adjacent coils defining an outer diameter, and further wherein the outer diameter is variable along at least a portion of a length of the first helical needle.  
     
     
         6 . The surgical apparatus of  claim 5 , wherein the outer diameter decreases proximally from the needle tip.  
     
     
         7 . The surgical apparatus of  claim 5 , wherein the outer diameter increases proximally from the needle tip.  
     
     
         8 . The surgical apparatus of  claim 5 , wherein the first helical needle includes a proximal portion, a central portion and a distal portion, and further wherein the outer diameter decreases from the central portion to the proximal portion and the distal portion.  
     
     
         9 . The surgical apparatus of  claim 5 , wherein the first helical needle includes a proximal portion, a central portion and a distal portion, and further wherein the outer diameter increases from the central portion to the proximal portion and the distal portion.  
     
     
         10 . The surgical apparatus of  claim 1 , wherein the helical needle assembly further includes: 
 a second helical needle concentrically arranged with the first helical needle, the second helical needle having an outer diameter less than an inner diameter defined by the first helical needle.    
     
     
         11 . The surgical apparatus of  claim 1 , wherein the helical needle assembly further includes: 
 a second helical needle wound parallel with the first helical needle.    
     
     
         12 . The surgical apparatus of  claim 1 , wherein the helical needle assembly further includes: 
 a second helical needle concentrically disposed within the first helical needle.    
     
     
         13 . The surgical apparatus of  claim 1 , wherein the first helical needle includes: 
 a central shaft, the shaft being hollow for delivering conductive fluid; and    a helical flight extending from an outer circumference of the central shaft.    
     
     
         14 . The surgical apparatus of  claim 1 , wherein the first helical needle includes: 
 a substantially straight tube, the tube being hollow for delivering conductive fluid;    a disc extending radially from the tube; and    a plurality of starter threads extending from the disc spaced from the tube, the plurality of starter threads defining a helical pattern.    
     
     
         15 . The surgical apparatus of  claim 1 , wherein the first helical needle forms openings along at least a portion of an outer diameter for delivering conductive fluid.  
     
     
         16 . The surgical apparatus of  claim 1 , wherein the first helical needle forms a continuous slit along an outer diameter for delivering conductive fluid.  
     
     
         17 . The surgical apparatus of  claim 1 , wherein the first helical needle forms a continuous slit along an inner diameter for delivering conductive fluid.  
     
     
         18 . A surgical system for creating a virtual electrode to ablate bodily tissue, the system comprising: 
 a fluid source maintaining a supply of conductive fluid;    a current source for selectively supplying a current; and    a surgical instrument including: 
 an elongated device for forming a helical needle configured to engage bodily tissue, the helical needle being hollow and fluidly connected to the fluid source for delivering the conductive fluid and terminating in a needle tip,  
 an electrode associated with the helical needle, the electrode being connected to the current source for applying a current to conductive fluid delivered from the helical needle to create a virtual electrode.  
   
     
     
         19 . The surgical system of  claim 18 , wherein the helical needle includes a plurality of adjacent coils, and further wherein a pitch between each of the plurality of adjacent coils is variable.  
     
     
         20 . The surgical system of  claim 18 , wherein the helical needle forms openings along at least a portion of an outer diameter of the first helical needle for delivering conductive fluid.