Evaluation of Autonomic Functions by Heart Rate Variability after Stenting in Patients with Carotid Artery Stenosis

Objective Although carotid stenting is an effective treatment for severe carotid stenosis, it has been associated with alterations in autonomic functions during or shortly after the procedure. Heart rate variability (HRV) is an established tool for the asessment of autonumic functions. In this study, our aim was to investigate the relation between the alterations in autonomic functions and HRV by Holter monitoring parameters. Methods Patients (19 male, 8 female) that are suitable for carotid artery stenting, without a history of hypertension, diabetes mellitus, severe coronary artery or valvular heart disease, were enrolled to our study. Short-term HRV analysis recordings were obtained at the beginning, and after the procedure. The square root of the mean squared differences of successive NN intervals (RMSSD), total frequency, low frequency (LF), high frequency (HF), normalized units LF (LFnu), normalized units HF (HFnu), LF/HF ratios were analyzed. Results were statistically analysed by using Wilcoxon test. Results Total frequency did not show any significant changes after the procedure (1101 +/- 829, 981 +/- 855). While RMSSD and HFnu values significantly increased respectively (23 +/- 12/33 +/- 22, and 22 +/- 10/35 +/- 10, p < 0.05) after the procedure, HF values increased nonsignificantly after the procedure (82 +/- 92/92 +/- 108). LF, LFnu, and LF/HF values were significantly decreased after the procedure. (228 +/- 166/112 +/- 100, 70 +/- 15/55 +/- 18, 4 +/- 2.5/2.1 +/- 2, respectively, p < 0.05) Conclusions While RMSSD and HF are used as markers of vagal activity, LF is a marker of sympathetic modulation and LF/HF ratio shows sympathovagal balance. In our study, we showed that carotid artery stenting is associated with increase in parasympathetic activation, and this finding is demonstrated by HRV parameters.