Abstract: Lesion size or volume prediction shortly after the onset of an ablation procedure can inform or control the ablation procedure. The prediction and/or control is made without regard to an actual detected temperature in the vicinity of the ablation electrodes. As a consequence, the system has utility with irrigated catheter constructions and other situations in which local irrigation in the vicinity of an ablation site would otherwise interfere with a prediction or control scheme that solely relies upon temperature measurements.

Abstract: Lesion size or volume prediction shortly after the onset of an ablation procedure can inform or control the ablation procedure. The prediction and/or control is made without regard to an actual detected temperature in the vicinity of the ablation electrodes. As a consequence, the system has utility with irrigated catheter constructions and other situations in which local irrigation in the vicinity of an ablation site would otherwise interfere with a prediction or control scheme that solely relies upon temperature measurements.

Abstract: Impedance and capacitance-related parameters are monitored in the electrical circuit of a tissue-ablation apparatus wherein RF electrical power is administered at predetermined frequencies. Tissue temperature has been found to correlate well with low-frequency impedance, or with the resistive component of impedance at any frequency. Therefore, one or both of these parameters are calculated and tracked during the ablation procedure to estimate tissue temperature. Similarly, tissue lesion formation has been found to correlate well with changes in the capacitive component of tissue impedance. Thus, this parameter can be used to track tissue lesion formation during the ablation procedure. The ratio of tissue-to-blood interface with the ablation electrode is estimated by measuring impedance at a very low frequency and a very high frequency. The difference between these two values divided by the high-frequency value is taken to be a measure of such ratio.