Kauzální vztah mezi systolickým krevním tlakem a srdečními intervaly u pacientů s míšní lézí
| Title in English | A causal relationship between systolic blood pressure and cardiac intervals in patients after spinal cord injury |
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| Authors | |
| Year of publication | 2015 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Introduction: The height and the extent of the spinal cord injury (SCI) caused not only sensory deficiency but also cardiovascular regulation impairment. Chronotropic influence of parasympaticus on cardiovascular system is intact, but baroreflex function is disturbed by interruption of descendent sympathetic nerves by spinal cord lesion. Aim of the study was estimation of the baroreflex blood pressure (BP) regulation impairment in patients with cervical (CSCI) and thoracic (TSCI) SCI compared with healthy controls (Con). For the estimation causal analysis of the interaction between systolic BP (SBP) and inter-beat intervals (IBI) was used. Methods: Continual BP was measured in 13 CSCI (median: 29 years), 9 TSCI (27 years) and 13 Con (27 years) in two phases of experiment: pR - resting condition in siting position with paced breathing on frequency 0.33 Hz, pV - passive verticalization with Balance Thera-trainer. From continual BP sequences of SBP and IBI were evaluated. Using linear bivariate autoregressive model causal gain (Gain_sbp-ibi) and causal coherence (Coh_ibi-sbp) were estimated. Gain_sbp-ibi in practice represented baroreflex sensitivity (BRS). Coh_ibi-sbp represented linear coupling between SBP and IBI given by baroreflex nerve pathways. Differences between both phases of experiment as well as differences between groups were examined. Results: During pR, no differences between groups were found in both variables. pV led to increase of Coh_ibi-sbp in Con and TSCI and no change in CSCI. In the other hand pV led to decrease of Gain_sbp-ibi in CSCI and no change in Con and TSCI. This caused lower Coh_ibi-sbp and Gain_sbp-ibi in CSCI compared with the other two groups. Both parameters negatively correlated with spinal cord lesion height. Conclusion: Difference in BP regulation occurred only during orthostatic stress. In CSCI, transfer of variability from SBP to IBI via baroreflex was decreased, therefore orthostatic hypotension symptoms occurred. |
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