The human organism can be understood as a complex system of dynamic interactions regulating physiological functions to maintain a state of homeostasis. Mental stress disrupts homeostasis and triggers a cardiovascular response controlled by the autonomic nervous system (ANS). Although the underlying mechanisms are not yet fully understood, we hypothesize that the cardiovascular response leads to increased interactions within the ANS itself, whereas fewer interactions are required to maintain homeostasis. We investigated the effects of acute mental stress on dynamic interactions between 21 parameters of hemodynamics, heart rate variability, QT variability, respiration, and skin conductance in 35 healthy subjects. After a period of homeostasis (baseline), acute mental stress was induced by an arithmetic task complemented by several other stressors. To characterize dynamic interactions, we calculated transfer entropy for quantifying the connectivity between all combinations of the 21 parameters during baseline and acute mental stress. Statistical group comparisons were performed using the Wilcoxon signed-rank test. Significant changes were found in the dynamic interactions of 70 combinations between baseline and acute mental stress (p<0.05). Overall connectivity increased by 12.1 % compared to baseline (p<0.001). Specifically, we observed a connectivity decrease of 7.5 % for the left ventricular work index (LVWI) and a connectivity increase of 5.4 % for the variability ratio (VR). While LVWI describes hemodynamic activity, VR represents the ratio of short-term QT interval variability to short-term RR interval variability as a measure of ANS activity. Our results indicate that acute mental stress leads to increased autonomic regulation. Thereby, the ANS appears to have a leading role within the complex network of dynamic interactions, while interactions that are dominant during homeostasis decrease. The characterization of dynamic interactions during acute mental stress provides insights for a better understanding of the behavior of the autoregulatory system.
|Title of host publication
|Computing in Cardiology Conference (CinC)
|Number of pages
|Accepted/In press - 2023