Kauzální vztah mezi tepovými intervaly a systolickým krevním tlakem: změny s věkem v průběhu dospívání

Title in English Causal interaction between inter-beat intervals and systolic blood pressure: changes with age during adolescence


Year of publication 2015
Type Conference abstract
MU Faculty or unit

Faculty of Medicine

Description Introduction: Blood pressure oscillations are transferred in inter-bear intervals (IBI) via baroreflex. Simultaneously blood pressure is influenced by IBI in forward mechanical way. Both pathways of interaction create closed-loop. Bivariate autoregressive model enables estimation of traditional closed-loop gain (Gain_sbp,ibi) as well as open-loop causal gain (Gain_sbp-ibi) from systolic blood pressure (SBP) to IBI. Open-loop gain describes only baroreflex transfer of variability from SBP to IBI, closed-loop additionally contains non-baroreflex component. Linear coupling between signals of IBI and SBP can be evaluated as non-causal coherence (Coh_ibi,sbp) and causal coherences in baroreflex and non-baroreflex ways (Coh_sbp-ibi, Coh_ibi-sbp). Using non-linear method based on conditional entropy causal coupling indices (C_sbp-ibi, C_ibi_sbp) can be computed to assess amount of information transferred between SBP and IBI in both ways separately. Aim of the study was estimation of the IBI – SBP interaction in children and adolescents. Methods: Continual blood pressure was measured in 335 young healthy volunteers (11 – 23 years) in resting condition, sitting position and paced breathing (0.33 Hz). Sequences of SBP and IBI were evaluated beat to beat from blood pressure. Results: Gain_sbp,ibi increased with age, Gain_sbp-ibi did not change. C_sbp-ibi, C_ibi_sbp, Coh_sbp, ibi and Coh_ibi-sbp did not change with age as well. On the other hand, Coh_ibi-sbp significantly decreased with age, mainly until 16 years. In each age group causal coherences and coupling indices in baroreflex way were lower than coherences and indices in non-baroreflex way. Conclusion: We proved that in resting conditions transfer of information from SBP to IBI was dominant regardless age. Increase of Gain_ibi,sbp and any change of Gain_ibi-sbp during maturation was given by decrease of causal coherence from SBP to IBI. Decrease of Gain_ibi-sbp was probably given by increase of complex influence on IBI.
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