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

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Title in English Causal interaction between systolic blood pressure and inter-beat intervals: changes with age between 11 and 23 years
Authors

SVAČINOVÁ Jana JAVORKA Michal NOVÁKOVÁ Zuzana ZÁVODNÁ Eva CZIPPELOVÁ Barbora HONZÍKOVÁ Nataša

Year of publication 2015
Type Conference abstract
MU Faculty or unit

Faculty of Medicine

Citation
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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