Autonomic impairment in advanced heart-failure patients revealed by nonlinear heart rate variability measured during exercise

Figures

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  Fig. 1. Distribution of HRV metrics. (a) Time-domain HRV [ms]. Boxplots depict MeanRR (left), SDRR (center) and RMSSD (right). (b) Frequency-domain HRV [%]. Boxplots depict normalized very low frequency (VLF, left), low frequency (LF, center) and high frequency (HF, right) power. (c) Information-theoretic domain HRV [nats]. Boxplots depict entropy (H, left), conditional entropy (CE, center) and self-entropy (SE, right). The boxplots illustrate the distribution of the data: the central line within the box represents the median (50th percentile); the box edges denote the first quartile (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Q_1$$\end{document}, 25th percentile) and the third quartile (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Q_3$$\end{document}, 75th percentile), with the box length representing the Interquartile…

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  Fig. 2. Frequency-domain HRV results. Power spectral density (PSD) profiles computed as the median across all subjects (VLF, blue; LF, green; HF, red) across the three exercise phases.

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  Fig. 3. Surrogate data analysis results for Self-Entropy (SE) statistical assessment across the three exercise stages. Bars represent the percentage of RR time series exhibiting statistically significant nonlinear dynamics. Numbers above each bar report the count of time series showing a significant SE value.

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  Fig. 4. Distribution of HRV metrics across groups. (a) Frequency-domain HRV [%]. Boxplots depict normalized very low frequency (VLF, left), low frequency (LF, center) and high frequency (HF, right) power. (b) Information-theoretic domain HRV [nats]. Boxplots depict entropy (H, left), conditional entropy (CE, center) and self-entropy (SE, right). The boxplots illustrate the distribution of the data: the central line within the box represents the median (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$50\textrm{th}$$\end{document} percentile); the box edges denote the first quartile (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Q_1$$\end{document}, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek}…

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  Fig. 5. Kaplan–Meier curves depicting cardiovascular survival stratified by tertiles of self-entropy (SE) values measured during the early exercise phase. Subjects were divided into three groups based on the lower (low; red), middle (medium; green) and upper (high; blue) thirds of SE distribution. Survival probabilities across groups were compared using the log-rank test, with the corresponding p-value (p). Vertical tick marks show censored patients. The number at risk in each tertile at 0, 200, 400, 600 and 800 days from enrollment is displayed below the plot.