Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
The effect of different anesthetics on the function of the autonomic nervous system (ANS) is not well known. As a relatively new treatment option, ganglionated plexus (GP) ablation aims to modify the behavior of the cardiac ANS to prevent some/all of the autonomic processes occurring in vasovagal syncope (VVS) by using endocardial ablation techniques.
Purpose
The purpose of this study was to determine the effects midazolam and propofol on the vagal response (VR) characteristics during GP ablation in patients with vasovagal syncope (VVS).
Methods
Forty consecutive patients undergoing GP ablation for VVS were divided to receive local anesthesia with midazolam (group 1, n = 29) or general anesthesia with propofol (group EA, n = 11). All GP sites were detected by using previously defined fragmented electrogram based strategy. VR was defined on 3 levels: 1) R-R interval increased by 50% (level 1); 2) R-R interval increased by 20-50% (level 2); and 3) R-R interval increase lower than 20% (level 3).
Results
Baseline characteristics and mean follow-up times were comparable between groups. In both groups, the left superior GP (LSGP) was the most common GP site at which a VR was observed. However, there was a significant difference between groups for level of VR. While ablation on the LSGP caused a level 1 VR in 89.6% of cases in group 1, level 1 VR was seen in 22.2% of cases in group 2 (p < 0.0001). Similarly, ratio of level 1 VR during ablation on the left inferior GP (LIGP) was significantly lower in group 2 (44.8% vs 9%, p = 0.034). Once cut-off for VR was decreased to level 2, the ratio of (+) VR increased to 90.9% during ablation on the LSGP in group 2. Level 2 VR was detected in 45.4% of cases during ablation on the LIGP. Ratio of positive VRs in any level was lower than 20% during ablation on the right superior and inferior GPs in both groups. During a mean follow-up time of 12.1 ± 7 months, all but 2 (5%) of 40 patients were free of syncope.
Conclusions
The autonomic nervous tone might be affected in different ways by local and general anesthesia. Propofol may reveal a shift in the sympathovagal balance toward sympathetic predominance which may cause a blunting on VR during GP ablation. Further randomized, controlled and multicenter studies should be performed to confirm these findings.