Publication details

Development of causal interactions between systolic blood pressure and inter-beat intervals in adolescents



Year of publication 2015
Type Article in Periodical
Magazine / Source Physiological Research
MU Faculty or unit

Faculty of Medicine

Field Physiology
Keywords Baroreflex; Causality; Conditional entropy; Autonomic nervous system; Adolescents
Description Systolic blood pressure (SBP) changes control the cardiac inter-beat intervals (IBI) duration via baroreflex. Conversely, SBP is influenced by IBI via non-baroreflex mechanisms. Both causal pathways (feedback – baroreflex and feedforward – non-baroreflex) form a closed loop of the SBP – IBI interaction. The aim of this study was to assess the age-related changes in the IBI – SBP interaction. We have non-invasively recorded resting beat-to-beat SBP and IBI in 335 healthy subjects of different age, ranging from 11 to 23 years. Using a linear autoregressive bivariate model we obtained gain (GainSBP,IBI, used traditionally as baroreflex sensitivity) and coherence (CohSBP,IBI) of the SBP–IBI interaction and causal gain and coherence in baroreflex (GainSBP IBI, CohSBP IBI) and coherence in non-baroreflex (CohIBI SBP) directions separately. A non-linear approach was used for causal coupling indices evaluation (CSBP IBI, CIBI SBP) quantifying the amount of information transferred between signals. We performed a correlation to age analysis of all measures. CohIBI SBP and CIBI SBP were higher than CohSBP IBI and CSBP IBI, respectively. GainSBP,IBI increased and CohSBP IBI decreased with age. The coupling indices did not correlate with age. We conclude that the feedforward influence dominated at rest. The increase of GainSBP,IBI with age was not found in the closed loop model. A decrease of CohSBP IBI could be related to a change in the cardiovascular control system complexity during maturation.
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