Patent ID: 6056745
Filing Date: 2000-05-02
Classification: A61B,A61M

Abstract:
A system for ablating body tissue comprisingan electrode adapted to contact tissue to form a tissue-electrode interface, the electrode being coupled to a source of ablation energy for transmitting ablation energy at a determinable ablation power level into tissue to form, over a prescribed ablation time period, a therapeutic result including a lesion that extends beneath the tissue-electrode interface to a boundary depth between viable and nonviable tissue and a maximum tissue temperature developed within the lesion between the tissue-electrode interface and the boundary depth,a heat removal element in thermal conductive contact with the electrode and operable to remove heat from the electrode at a determinable heat removal rate,a temperature sensing element in thermal conductive contact with the electrode to sense temperature of the electrode, anda controller coupled to the electrode, the heat removal element, and the temperature sensing element and includingan input element for inputting a desired therapeutic result including at least a targeted lesion boundary depth, anda processing element coupled to the input element for retaining a function that correlates an observed relationship among lesion boundary depth, ablation power level, ablation time, tissue temperature beneath the tissue-electrode interface, and electrode temperature; for sampling an actual operating condition including the ablation power level at which the electrode transmits ablation energy, the heat removal rate, and the temperature of the electrode sensed by the temperature sensing element, without sampling an actual tissue temperature beneath the tissue-electrode interface; for comparing the actual operating condition to the function to derive a prediction of the maximum tissue temperature condition beneath the tissue-electrode interface based upon the desired therapeutic result; and for controlling the ablation power level transmitted by the electrode, or the heat removal rate, or both, at least in part, upon the prediction of the maximum tissue temperature and without sampling an actual tissue temperature beneath the tissue-electrode interface.