Sympathetic and vagal control differently affect entropy (MSE) and fractal properties (DFA) of heart rate variability, with atropine reducing short-scale MSE and atenolol decreasing short-scale DFA.
Does selective or combined autonomic blockade affect the complexity of heart rate dynamics (MSE and DFA) in conscious male Wistar rats?
Sympathetic and vagal control differently affect entropy and fractal properties of heart rate variability, clarifying the physiological interpretation of these nonlinear approaches.
Analysis of heart rate variability (HRV) by nonlinear approaches has been gaining interest due to their ability to extract additional information from heart rate (HR) dynamics that are not detectable by traditional approaches. Nevertheless, the physiological interpretation of nonlinear approaches remains unclear. Therefore, we propose long-term (60 min) protocols involving selective blockade of cardiac autonomic receptors to investigate the contribution of sympathetic and parasympathetic function upon nonlinear dynamics of HRV. Conscious male Wistar rats had their electrocardiogram (ECG) recorded under three distinct conditions: basal, selective (atenolol or atropine), or combined (atenolol plus atropine) pharmacological blockade of autonomic muscarinic or β 1 -adrenergic receptors. Time series of RR interval were assessed by multiscale entropy (MSE) and detrended fluctuation analysis (DFA). Entropy over short (1 to 5, MSE 1–5 ) and long (6 to 30, MSE 6–30 ) time scales was computed, as well as DFA scaling exponents at short (α short , 5 ≤ n ≤ 15), mid (α mid , 30 ≤ n ≤ 200), and long (α long , 200 ≤ n ≤ 1,700) window sizes. The results show that MSE 1–5 is reduced under atropine blockade and MSE 6–30 is reduced under atropine, atenolol, or combined blockade. In addition, while atropine expressed its maximal effect at scale six, the effect of atenolol on MSE increased with scale. For DFA, α short decreased during atenolol blockade, while the α mid increased under atropine blockade. Double blockade decreased α short and increased α long . Results with surrogate data show that the dynamics during combined blockade is not random. In summary, sympathetic and vagal control differently affect entropy (MSE) and fractal properties (DFA) of HRV. These findings are important to guide future studies. NEW & NOTEWORTHY Although multiscale entropy (MSE) and detrended fluctuation analysis (DFA) are recognizably useful prognostic/diagnostic methods, their physiological interpretation remains unclear. The present study clarifies the effect of the cardiac autonomic control on MSE and DFA, assessed during long periods (1 h). These findings are important to help the interpretation of future studies.
Silva et al. (Fri,) reported a other. Selective (atenolol or atropine) or combined pharmacological blockade vs. Basal condition was evaluated on Time series of RR interval assessed by multiscale entropy (MSE) and detrended fluctuation analysis (DFA). Sympathetic and vagal control differently affect entropy (MSE) and fractal properties (DFA) of heart rate variability, with atropine reducing short-scale MSE and atenolol decreasing short-scale DFA.