Age-dependent contribution of intrinsic mechanisms to sinoatrial node function in humans

Figures

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  Figure 1. Representative example of ECG data and BIV analysis of a young patient. (A) Data acquisition process, which included ECG Holter recording in basal state (BSL), in anesthesia state and following autonomic blockade under anesthesia (ABK). Representative example of (B) ECG recordings, (C) intervalogram, (D) beat interval histogram, (E) normalized power spectral density (PSD), (F) frequency bands and (G) multiscale entropy (MSE) in all three states.

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  Figure 2. Representative example of ECG data and BIV analysis of an adult patient. (A) Data acquisition process, which included ECG Holter recording in basal state (BSL), in anesthesia state and following autonomic blockade under anesthesia (ABK). Representative example of (B) ECG recordings, (C) intervalogram, (D) beat interval histogram, (E) normalized power spectral density (PSD), (F) frequency bands and (G) multiscale entropy (MSE) in all three states.

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  Figure 3. The relation between selected beat interval variability in each state in young and adult patients. (A) The average level of (A) beat interval (BI), (B) standard deviation (STD) of BIs, (C) SD2, and (D) normalized very-low-frequency (VLF) band, between each state (BSL, Anesthesia, ABK) in young and adult patients. Significant comparisons are based on FDR adjusted p-values from post-hoc pairwise comparisons from the mixed ANOVA models, *p–v < 0.05, **p–v < 0.001.

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  Figure 4. Linear association between beat interval and age. (A) Average beat interval (BI) as a function of age, of all recordings in basal state (BSL; blue), anesthesia (purple) and autonomic blockade under anesthesia (ABK; orange). Dashed vertical line represents 21 years of age (cut off age of the two age groups). The linear regression line represents the linear regression between BI and age. (B) Average heart rate as a function of age, of all ABK recordings under anesthesia (light orange). The linear regression lines were highly similar to those obtained in previous publications.

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  Figure 5. Effect of anesthesia on ANS and SAN signatures in human basal electrocardiogram recordings. Presented is the MSE at basal, anesthesia, and after filter for (A) young and (B) adult patients (bolded line represents the mean, error bars represent SE, shaded band represents 95% confidence interval). For young patients, the filter included band-pass filtering of a segment of the VLF band and all LF bands. The data were divided into train (n = 5) and test (n = 9) sets. The similarity between the anesthesia state and the filter is expressed by the high mean p-value across all scales, which was found to be 0.46 and 0.31 for train and test groups, respectively. For adult patients, the filter included a segment of the VLF band, all LF bands, and a segment of the HF band. The data were divided into train (n = 6) and test (n = 5) sets. The similarity between the anesthesia state and the filter is expressed by the high mean p-value across all scales, which was found to be 0.34 and 0.23 for train and test groups, respectively. (ANS autonomic nervous system, SAN sinoatrial node, ECG electrocardiogram, MSE multiscale entropy, SE standard error).

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  Figure 6. The ANS and SAN signatures in human basal ECG. (A) The MSE at anesthesia, autonomic blockade (ABK), and after applying a filter on the data from young patients. The filter included band-pass filtering of most of the LF band and almost all HF bands, as shown on the spectrum. The data were divided into train (n = 5) and test (n = 5) sets. The similarity between ABK state and the filter is expressed by the high mean p-value across all scales, which was found to be 0.63 and 0.55 for the train and test sets, respectively. (B) The MSE at basal, ABK under propofol and dexmedetomidine anesthesia, and after applying filter on the data from adult patients. The filter included most of the VLF and LF bands and almost all HF bands. The data were divided into train (n = 9) and test (n = 5) sets. The similarity between the anesthesia state and the filter is expressed by the high mean p-value across all scales, which was found to be 0.69 and 0.55 for the train and test sets, respectively. (MSE bolded line represents the mean, error bars represent SE, shaded band represents 95% confidence interval). (ANS autonomic nervous system, SAN sinoatrial node, ECG electrocardiogram, MSE multiscale entropy,…