Patent ID: 6113592
Filing Date: 2000-09-05
Classification: A61B,A61N

Abstract:
Apparatus for ablating tissue at an ablation site in the heart of a human being while avoiding the possibility of tip coagulation, tissue sticking or tissue perforation, said apparatus comprising in combination:(a) a source of RF energy for irradiating the tissue at the ablation site to cause a temperature rise of the tissue at the ablation site;(b) a catheter having a first electrode for contactingly engaging the ablation site and for irradiating the tissue with RF energy to heat the tissue at the ablation site, said electrode comprising a first electrode of material having a first work function;(c) transmission means for conveying RF energy from said source to said first electrode;(d) a second electrode displaced from said first electrode and of material having a second work function different from the first work function for electrically contacting an area of tissue of the human being;(e) a galvanic cell formed by said first electrode, said second electrode and the tissue of the human being serving as an electrically interconnecting electrolyte for generating an electrical signal having a peak value corresponding with initial occurrence of ablation of the tissue at the ablation site followed by a decreasing value, an inflection in value and a decreasing value; and(f) a control circuit responsive to said electrical signal generated by said galvanic cell for regulating the operation of said source of RF energy to control RF radiation of the ablation site before and after said electrical signal has reached a peak value and to terminate radiation of the ablation site upon detection of the inflection in value of said electrical signal.