Patent ID: 6143018
Filing Date: 2000-11-07
Classification: A61B,A61N

Abstract:
A process for thermally obliterating biological tissue by means of laser radiation transmission through a light waveguide, comprising the steps ofintroducing a light waveguide's distal end into a biological tissue through a multichannel hollow needle and apparatus;injecting a biocompatible fluid, having a selected viscosity, into said tissue near said distal end, wherein said fluid essentially scatters said laser radiation but does not absorb said laser radiation;creating a deposit of said scattering fluid surrounding said lightguide's distal end which functions as an exit surface of said laser radiation;creating said scattering fluid deposit substantially from two components, an essentially transparent component and a highly light-scattering component, wherein said components are injected into said tissue through separate channels within a concentric double channel hollow needle such that said transparent component is injected through an inner channel and said highly light-scattering component is injected through a concentric outer channel enveloping said transparent component,wherein said viscosity of said scattering fluid has been selected to diffuse said scattering fluid within said tissue to be thermally obliterated prior to and during laser irradiation in such a way that said scattering fluid deposit maintains a stable structure for the duration of treatment; andtransmitting said laser radiation through said waveguide and into said scattering fluid within said biological tissue to coagulate and to cause necrosis of said tissue.