Electrophysiological Parameters of Vagal Denervation
In this study, both groups exhibited significant electrophysiological changes in all parameters related to the vagal effect. There was a notable increase in sinus rate and the Wenckebach point, along with a reduction in sinus node recovery time, sinoatrial conduction time, and AV refractory period. All other parameters unrelated to the vagus showed no significant changes, as detailed in Table 2 and Table 3.
The original CNA study we had no ECVS3. Ablations were directed towards areas with the highest density of AF-Nests, typically associated with the neuro-atrial interface in normal heart3,19,24,25. Additionally, extended ablations were applied to anatomical regions that presumably overlapped with the primary GPs, which also tend to harbor a higher number of AF-Nests. The goal was to achieve sufficient depth for epicardial GP ablation. In cases with a high risk of esophageal thermal injury, mechanical esophageal displacement was performed using a transesophageal echocardiogram transducer. Based on the initial CNA technique, relying on spectral mapping obtained through online spectral analysis26, we developed the Fractionation Mapping, making the innervation tracking easier and faster27, Figure 5.
Figure 5
While the ablated points appeared adequate, the depth of thermal effect on the atrial wall and epicardium, and consequently the extent of denervation, could not be measured. The increase in sinus rate and the Wenckebach point, along with the shortening of the AH and EAVRP, serve as important indicators of denervation (as detailed in Table 2 and Table 3); however they represent indirect parameters and do not necessarily indicate a full effect. Immediate results may be achieved by eliminating superficial fibers, but long-term outcomes depend on the disappearance of deep neural bodies. There are numerous instances where, despite modifications in all EP parameters, ECVS reveals a significant residual vagal response28, often leading to clinical recurrence. In this study, we found that although there was no statistically significant difference in the electrophysiological parameters of acute vagal denervation (as shown in Table 3), there was a significant difference in long-term outcomes, suggesting that immediate electrophysiological response alone may not be enough to predict the long-term efficacy of CNA.