Electrosurgical implement for tunneling through tissue

Claim 1

An electrosurgical instrument for tunneling through a tissue body comprising: (a) a relatively thin, flexible conductive core wire of a predetermined diameter having a proximal end and a distal end; (b) a continuous layer of insulating material adhered to said core wire except for an exposed portion at said proximal and distal ends, said layer being sufficiently thin and pliable so as not to impair the flexibility of said core wire; (c) a helical coil of conductive wire of a predetermined length wrapped onto said layer of insulating material and extending over substantially the entire length thereof with adjacent convolutions of said helical coil abutting one another, said helical coil having a proximal end and a distal end and a coating of insulation on the exterior surface of said coil except for a predetermined number of convolutions at said distal end thereof, said exposed portion at said distal end of said core wire flush with or extending beyond said distal end of said coil and spaced therefrom by a predetermined gap, said gap free of electrical insulation, said coil wrapped about said core wire exhibiting a predetermined flexibility sufficient to allow same to be routed through a tortuous path within the lumen of a hollow body organ, said core wire being immovable longitudinally relative to said helical coil and the surface area of said exposed portion of said core wire being substantially less than the surface area of said predetermined number of convolutions; and (d) terminal means connected to said exposed portion of said proximal end portion of said core wire and to said proximal end of said coil for receiving a voltage therebetween sufficient to create a spark discharge between said exposed portion of said distal end of said core wire and said predetermined number of convolutions to effect tunneling through said tissue body.