Autonomic Responses during Atrial Fibrillation Ablation

Abstract

Left atrial radiofrequency catheter ablation (RFCA) is a therapy for atrial fibrillation. RFCA may alter sensory input from left atrium and pulmonary veins. It is speculated that RFCA may alter autonomic afferents and alter indices of sympathetic function. Although prior studies have shown that RFCA may alter autonomic function, which was assessed with heart rate variability (HRV), the effects of left atrial RFCA on sympathetic nerve activity have not been assessed. In this study, we hypothesized that RFCA would raise muscle sympathetic nerve activity (MSNA) during and after the RFCA procedure. Total of 18 patients (16 M, 2 F, 57 ± 3 years, 181 ± 2 cm, 97 ± 5 kg) were studied. In Protocol 1 (n = 10), the ECG, BP and MSNA from the peroneal nerve were recorded through the RFCA procedure in the electrophysiology laboratory. In Protocol 2 (n = 8), ECG, BP and MSNA were recorded before (within one week) and one day after the RFCA in a research laboratory. In Protocol 1, MSNA was obtained prior (n = 9), during (n = 3) and just post (within 15 min, n = 7) the RFCA procedure. Compared to prior RFCA, MSNA decreased during (28.4 ± 3.7 to 16.0 ± 2.6 bursts/min, P < 0.05) and just post (28.6 ± 3.1 to 16.5 ± 4.1 bursts/min, P < 0.05) the RFCA. Cardiac sympathetic tone (HRV) also decreased (prior, during, post LF/HF: 0.64 ± 0.15, 0.49 ± 0.11, 0.16 ± 0.04, P < 0.05, n = 10). Vagal tone (HRV indexes: RMSSD, SDSD, HF) increased during RFCA (all P < 0.05, n = 10). In Protocol 2, MSNA increased one day after RFCA (21.3 ± 3.7 to 35.7 ± 2.6 bursts/min, P < 0.05, n = 6), and blood pressure did not change. Vagal tone (HRV indexes) decreased (all P < 0.05, n = 8), while LF/HF also tended (P = 0.09, n = 8) to decrease one day after RFCA. Despite body motions and electronic noise during the RFCA procedure, we successfully obtained MSNA recordings during the RFCA procedure. The MSNA data suggest that the sympathetic activity is suppressed, and the HRV indexes suggest that the vagal tone is activated during the procedure. We speculate that the radiofrequency energy stimulates the vagal afferents, which in turn induces the observed effects during the procedure. Our data suggest the RFCA induces autonomic denervation in the heart and induces decreases in vagal and cardiac sympathetic tone one day post procedure. The rise in the sympathetic output to muscle after the procedure may represent a compensatory response to maintain blood pressure.Support or Funding InformationSupported by American Heart Association Grant 15GRNT24480051 (Cui), Penn State Heart and Vascular Institute Penny A. Garban Endowment (Cui), National Institutes of Health Grants P01 HL096570 (Sinoway) and UL1 TR000127 (Sinoway).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.