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Selective vagal denervation of the atria eliminates heart rate variability and baroreflex sensitivity while
1Krannert Institute of Cardiology, Indiana University School of Medicine, and the Roudebush Veterans Administration Medical Center, Indianapolis 46202-4800, USA.
Insights
Radiofrequency catheter ablation (RFCA) of epicardial fat pads selectively denervated the atria and nodes but preserved ventricular vagal innervation. Heart rate variability and baroreflex sensitivity reflect sinus node activity, not ventricular efferent vagal signals.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Research
- Electrophysiology
Background:
- Epicardial fat pads contain autonomic nerve fibers.
- Radiofrequency catheter ablation (RFCA) is used to target these structures.
Purpose of the Study:
- To determine if RFCA of 3 specific epicardial fat pads, known to denervate atria and nodes, also affects ventricular vagal innervation.
Main Methods:
- Vagal innervation of ventricles assessed by ventricular effective refractory period changes during vagal stimulation.
- Heart rate variability (HRV) and baroreflex sensitivity (BRS) were measured.
- RFCA was performed on 3 epicardial fat pads.
Main Results:
- RFCA denervated sinus and AV nodes and atria but did not affect ventricular vagal innervation.
- Vagal denervation significantly decreased HRV and eliminated BRS.
- HRV and BRS changes primarily reflect sinus node vagal activity, not ventricular efferent signals.
Conclusions:
- Selective vagal denervation of atrial and nodal targets via epicardial fat pad ablation preserves ventricular innervation.
- HRV and BRS are not reliable indicators of efferent vagal activity at the ventricular level.
Background:
The purpose of this study was to test whether radiofrequency catheter ablation (RFCA) of 3 epicardial fat pads that resulted in efferent vagal denervation of the atria and sinus and atrioventricular nodes also denervated the ventricles.
Methods And Results:
Vagal innervation of the ventricles was determined by measuring prolongation of ventricular effective refractory period induced by bilateral vagal stimulation (20 Hz, 10 V, 4 ms). Changes in heart rate variability (HRV) and baroreflex sensitivity (BRS) were also examined. We found that RFCA of the 3 epicardial fat pads vagally denervated the sinus and AV nodes and atria without affecting vagal innervation of the ventricles, indicating that efferent vagal fibers to the ventricles do not travel through the 3 epicardial fat pads. Parameters of time-domain variables decreased significantly; the total-power, high-frequency, and low-frequency components of frequency-domain variables decreased significantly; and the ratio of the low- and high-frequency components increased significantly after chronic vagal denervation. Vagally modulated sinus arrhythmia and BRS were also eliminated after chronic vagal denervation. These data also indicate that HRV and BRS represent vagal activity at the level of the sinus node and may not accurately reflect efferent vagal activity at the ventricular level.
Conclusions:
Selective vagal denervation of the sinus and AV nodes and atria decreased HRV and eliminated BRS while preserving ventricular innervation.