MAPPING R- F ABLATING LIQUID INJECTING SCREW- IN CATHETER MOUNTED ELECTRODE

摘要

A method and apparatus for ablation of body tissue. A catheter provided with a hollow needle is employed both for mapping the location to be ablated by injection of an excitability reducing agent and for ablating tissue, employing RF energy in conjunction with an injected, conductive fluid. The hollow needle can be shaped in the form of a spring like helix intended to pierce the surface of the organ and then to penetrate into the tissue under the action of a rotation imposed upon the catheter by the operator. The penetration of the electrode into the tissue guarantees efficiency of ablation and prevents dispersion of energy on not targeted locations. A second ablation electrode may be present in a recessed cavity at the catheter distal end. The injection of cool or warm liquids through the helix like needle requires the liquid to be kept at the wished-for temperature along the length of the catheter. To this objective the catheter main lumen is made into three coaxial channels, the innermost of which carries the injection liquid, and the two others create a two way circuit where another heated or cooled liquid is forced to circulate to maintain the temperature of the injection liquid in the innermost tube at the distored level.