SELECTIVE VAGAL DENERVATION OF THE ATRIA ELIMINATES HEART-RATE-VARIABILITY AND BAROREFLEX SENSITIVITY WHILE PRESERVING VENTRICULAR INNERVATION

Background-The purpose of this study was to test whether radiofrequenc y catheter ablation (RFCA) of 3 epicardial fat pads that resulted in e fferent vagal denervation of the atria and sinus and atrioventricular nodes also denervated the ventricles. Methods and Resnlts-Vagal innerv ation of the ventricles was determined by measuring prolongation of ve ntricular effective refractory period induced by bilateral vagal stimu lation (20 Hz, 10 V, 4 ms). Changes in heart rate variability (HRV) an d 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, indi cating that efferent vagal fibers to the ventricles do not travel thro ugh the 3 epicardial fat pads. Parameters of time-domain variables dec reased significantly; the total-power, high-frequency, and low-frequen cy components of frequency-domain variables decreased significantly; a nd the ratio of the low- and high-frequency components increased signi ficantly after chronic vagal denervation. Vagally modulated sinus arrh ythmia and BRS were also eliminated after chronic vagal denervation. T hese data also indicate that HRV and BRS represent vagal activity at t he level of the sinus node and may not accurately reflect efferent vag al activity at the ventricular level. Conclusions-Selective vagal dene rvation of the sinus and AV nodes and atria decreased HRV and eliminat ed BRS while preserving ventricular innervation.