Measurement and analysis of extracellular cardiac potentials to guide radiofrequency ablation therapy for fibrillation

Metrics for completeness of cardiac antiarrhythmic ablation lesions are needed to guide ablation therapy. Extracellular bipolar cardiac potentials were measured on either side of the lesion in isolated rabbit hearts (N=25). Three analyses of the signals were examined as possible metrics. Variances in dominant frequency of fibrillatory recordings decreased after ablation by factors of 1.51 for the frequency-domain analysis using the Fast-Fourier Transform; and 1.45 for the time-domain analysis using intervals between super-threshold peaks. This suggests an increase in organization of fibrillation. Morphologies of the signals from different sides of the lesion examined with cross-correlation indicated no consistent change in morphology before vs. after ablation. Slow pacing to determine translesion stimulus-excitation delays (TED) showed that mean TED increased post-ablation, consistent with increased conduction path length. During fibrillation, no consistent change in TED was observed. Thus, certain metrics may be useful to distinguish lesion completeness.