Time and frequency domain analysis of long-term heart rate variability in an experimental model of diet-induced metabolic syndrome

Abstract

Background Metabolic syndrome (MetS) is defined as the set of at least three of the following conditions: central obesity, elevation of triglycerides, decreased in high-density lipoproteins, systemic hypertension and glucose intolerance. MetS is linked with a high prevalence of cardiovascular disease, including sudden cardiac death and atrial arrhythmias, which may be a consequence of changes related to the structure, function and autonomic control of the heart. One of the underlying mechanisms responsible could be the alteration of sinus node automaticity. Heart rate variability (HRV) analysis is a useful non-invasive tool for evaluating alterations in neural control of cardiac automaticity. Purpose To examine the changes in long-term HRV using time- and frequency- domain analyses in an experimental model of diet-induced MetS which develops all its components. Methods Male NZW rabbits were randomly assigned to control (n=10) or MetS group (n=10), fed with high-fat (10% coconut oil and 5% lard) and high sucrose (15% dissolved in water) diet during 28 weeks. At week 28, 24 hour ECG recording was performed (eMotion Faros 180, Mega Electronics®, 1 kHz). We analyzed 60 minutes of RR time series, comparing day (from 8:00 to 19:59 h) and night (from 20:00 to 7:59 h), and quantified the standard parameters of time and frequency domains: 1) Time domain: RR, SDNN, triangular index (Ti), RMSSD and TINN; 2) Frequency domain: very low (VLF), low (LF), high frequency (HF), and LF/HF index. Multivariate analysis of variance (MANOVA, factorial model) was used for statistical analysis (p<0.05). Results Time domain analysis showed a decrease in RR interval (p<0.001) and geometrical Ti (p=0.036) in MetS animals (Figure, A-B), indicative of an increased heart rate. The rest of parameters in the time domain (SDNN, RMSSD, TINN) were not modified. Further, in the frequency domain at FFT spectrum, we did find a significant decrease in the LF band (p=0.032) in MetS animals (Figure, C). The rest of the frequency domain parameters (VLF, HF and LF/HF index) remained unchanged. Conclusion MetS decreased RR interval duration and triangular index, suggesting an increased sympathetic activity during day and night. Those changes were reflected in LF modifications, and might be attributable to a deficiency in sympathetic-parasympathetic control, which requires adjustments to maintain normal autonomic balance. Collectively, these results could give insight into the autonomic mechanisms that underlie increased atrial arrhythmia susceptibility in MetS. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Generalitat Valenciana, University of Valencia

Electrifying insights into cardiac arrhythmias: from molecular mechanisms to therapeutic translations

“…Together, the combination of early metabolic syndrome detection through accessible heart rate variability biomarkers [1] and later post atrial fibrillation assessment of structural remodelling progression and arrhythmic risk [2] are both promising for clinical translation in the near term.…”

“…Most consider implications for the atria [1,2,[4][5][6], reflecting the dominant morbidity and mortality burden of atrial fibrillation in many parts of the world, with the balance studying ventricular electrical function [3,7,9]. The motivating pro-arrhythmic disease states are similarly varied and include metabolic syndrome [1], atrial fibrillation [2,4,6,8], long-QT syndrome [3], pulmonary arterial hypertension [5] and myocardial induced heart failure [9]. While some of the studies explicitly consider a range of scales or dimensions [3,5,6], others focus on the cellular or subcellular space [7,9], the whole heart [2,4,8] or non-invasive torso-scale signals [1].…”

“…They include in vivo [1,2], in silico [3][4][5][6][7], in vitro [8] and ex vivo [7,9] studies covering animal [1,7,9] and human [3,8] models and clinical imaging [2]. Most consider implications for the atria [1,2,[4][5][6], reflecting the dominant morbidity and mortality burden of atrial fibrillation in many parts of the world, with the balance studying ventricular electrical function [3,7,9]. The motivating pro-arrhythmic disease states are similarly varied and include metabolic syndrome [1], atrial fibrillation [2,4,6,8], long-QT syndrome [3], pulmonary arterial hypertension [5] and myocardial induced heart failure [9].…”

“…Together, the studies reported in this special edition of Interface Focus are a taster of the exciting research tracks currently pursued in the cardiac arrhythmia field. Some of these works are poised for clinical and health science translation [1,2], others present tantalizing new mechanistic insights and patient-specific pathways across complexity scales with digital models [3][4][5][6][7], while the final two studies seek to bridge from bench to bedside by examining the links between clinically accessible tissue structure and detailed function [8], as well as pharmaceutical interventions and outcomes [9].…”

Modifications of long-term heart rate variability produced in an experimental model of diet-induced metabolic syndrome

“…Data accessibility. All data generated or analysed during this study are included in the published study and electronic supplementary material [74].…”