Effect of Radiofrequency Catheter Ablation on Parasympathetic Denervation: A Comparison of Three Different Ablation Sites

Radiofrequency (RF) catheter ablation of supraventricular tachycardias (SVT) has been shown to result in local parasympathetic denervation. The purpose of this study was to estimate the correlation between RF cumulative energy and parasympathetic denervation at three different ablation sites. Methods: 45 patients who underwent RF ablation of 36 AV reentrant tachycardias and 9 AV nodal reentrant tachycardias were studied. Twenty patients had left free-wall accessory pathways (group L), 8 patients right free-wall accessory pathways (group R), and 17 patients septal accessory path ways (n = 8) or slow pathways (n -9)(groupS). Time and frequency domain analysis of heart rate variability on 24-hour ambulatory ECG recordings was performed before and after RF ablation, pNN50 and the high frequency (0.15 to 0.40 Hz, HF) component were measured to examine the effects on parasympathetic nerve activity. The values of Δ pNN50 and Δ HF were expressed as the percent change of pNN50 and HF that occurred after versus before RF ablation. Results: Both pNN50 and HF significantly decreased after RF ablation in all three groups. In group S, there was a significant correlation between RF cumulative energy and Δ pNN50r = 0.66, P < 0.01) or Δ HF (r = 0.58, P < 0,05). In contrast, there was no correlation between RF cumulative energy and Δ pNNSO or Δ HF in either group L or group R. Conclusion: These data suggest that RF ablation produces parasympathetic denervation at all three sites along the mitral or tricuspid annulus and that parasympathetic fibers may be located predominantly in the septal area.