(12) United States Patent ao) Patent No.: us 6,280,441 Bi
Ryan (45) Date of Patent: *Aug. 28,2001
(54) APPARATUS AND METHOD FOR RF LESIONING
(75) Inventor: Thomas Patrick Ryan, Fort Collins, CO (US)
(73) Assignee: Sherwood Services AG, Schaffhausen (CH)
( * ) Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions of 35 U.S.C. 154(a)(2).
Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 08/990,377
(22) Filed: Dec. 15, 1997
(51) Int. C I. A61B 17/36
(52) U.S. CI 606/45; 600/373; 606/41
To ablate target tissue a handle with proximal and distal ends connect to an interior passageway and along an axis. A semi rigid and helical effector at the distal end is along the axis and has a sharpened distal tip and a mount at its handle attachment. A source of radio frequency current supplies the effector and is insulated from the handle for delivery to bipolar and monopolar circuits. A return electrode connects between tissue and the source of radio frequency current. A sensor is carried on the handle positioned to measure target tissue ablation. A control couples the source of radio frequency current and the sensor for loop regulation of ablation. The effector is a wire bent into the helical shape with an insulating sleeve to prevent passage of radio frequency current near its mount. The sensor has a calculator to find impedance or temperature changes and the control examines for a rise. The effector is in an alternate a hollow tube bent into the helical shape and closed at its distal tip; the handle has a passage for fluid circulation. A return located on the effector insulating sleeve has a larger surface area than the distal tip. A bipolar delivery effector carries at least two electrodes supplied with current of opposite polarity between the electrodes. The effector is a framework with at least two supports for locating electrodes in spaced apart relationship about the distal tip. A plurality of electrodes are in an alternate coupled to the source of radio frequency current to receive opposite polarity from a multiplexer coupled electrically between the source of radio frequency current and the plurality of electrodes for selective delivery of radio frequency current of opposite polarity to at least two of the electrodes at the same time. An elongate shank extending from the mount to the helical shaped part of the effector for laparoscopic applications. Aportal near the distal tip diverts the sensor to a position to measure target tissue. A light based system has a fiber optic for measurement of radiation of the target tissue with a meter. The control has a power modulator to maintain the impedance at approximately its low point. A method of ablating subsurface tissue includes inserting the distal tip into an entry point, rotating the effector about its axis to screw the helical shape into the tissue, and delivering controlled amounts of radio frequency current to the tissue.
42 Claims, 18 Drawing Sheets