Irreversible changes in reactive and resistive components of impedance, particularly phase angle, correlate better with in vitro RF ablation lesion size than impedance alone.
Do biophysical parameters such as phase angle and impedance components accurately estimate myocardial lesion size during in vitro RF catheter ablation?
Monitoring phase angle and specific impedance components during RF ablation may provide a more accurate estimation of lesion size than standard impedance monitoring.
We report our experience with a system that utilizes changes in several biophysical characteristics of cardiac tissue to determine lesion formation and to estimate lesion size both on and off-line in vitro during radio frequency (RF) energy delivery. We analyzed the reactive and resistive components of tissue impedance and tracked the change of phase angle during RF ablation. We correlated the amount of tissue damage with these and other biophysical parameters and compared them with off-line analysis. We found that there are irreversible changes in the reactive and resistive components of impedance that occurred during tissue ablation. The irreversible changes of these components are greater in magnitude, and correlate better with the size of lesions than that of impedance alone that is currently used. Numerically, the best single on-line and off-line correlation for combined perpendicular and parallel electrode orientation was with phase angle. On-line and off-line capacitance and susceptance correlations were essentially similar suggesting that they may be useful as lesion size predictors, given these parameter's persistent change without temperature sensitivity. This study indicates that it is technically feasible to assess lesion formation using biophysical parameters.
He et al. (2003) studied Radio frequency catheter ablation. Assessment of biophysical parameters (phase angle, capacitance, susceptance) vs. Impedance alone was evaluated on Correlation of biophysical parameters with lesion size. Irreversible changes in reactive and resistive components of impedance, particularly phase angle, correlate better with in vitro RF ablation lesion size than impedance alone.