Key result
Surgical aortic valve replacement was associated with an increased degree of asynchrony between mean arterial pressure and mean cerebral blood flow at rest.
Why the study?
Cerebrovascular control involves multiple nonlinear mechanisms coupling mean arterial pressure and mean cerebral blood flow, but the utility of nonlinear information-domain tools to assess their asynchrony remains to be explored.
Does surgical aortic valve replacement alter the asynchrony between mean arterial pressure and mean cerebral blood flow?
Observational (n=23)
Does surgical aortic valve replacement alter the asynchrony between mean arterial pressure and mean cerebral blood flow?
Cross-entropy methods can noninvasively evaluate cerebrovascular control by assessing MAP and MCBF variability, revealing changes in asynchrony after SAVR at rest that disappear during standing.
Hypothesis-generating tools for MAP-MCBF asynchrony after valve surgery; leaves open their specificity for control versus reduced MAP variability.
Cerebrovascular control is carried out by multiple nonlinear mechanisms imposing a certain degree of coupling between mean arterial pressure (MAP) and mean cerebral blood flow (MCBF). We explored the ability of two nonlinear tools in the information domain, namely cross-approximate entropy (CApEn) and cross-sample entropy (CSampEn), to assess the degree of asynchrony between the spontaneous fluctuations of MAP and MCBF. CApEn and CSampEn were computed as a function of the translation time. The analysis was carried out in 23 subjects undergoing recordings at rest in supine position (REST) and during active standing (STAND), before and after surgical aortic valve replacement (SAVR). We found that at REST the degree of asynchrony raised, and the rate of increase in asynchrony with the translation time decreased after SAVR. These results are likely the consequence of the limited variability of MAP observed after surgery at REST, more than the consequence of a modified cerebrovascular control, given that the observed differences disappeared during STAND. CApEn and CSampEn can be utilized fruitfully in the context of the evaluation of cerebrovascular control via the noninvasive acquisition of the spontaneous MAP and MCBF variability.
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Porta et al. (2022) conducted an observational in Surgical aortic valve replacement (n=23). Surgical aortic valve replacement (SAVR) vs. Before SAVR was evaluated on Degree of asynchrony between spontaneous fluctuations of mean arterial pressure and mean cerebral blood flow. Surgical aortic valve replacement was associated with an increased degree of asynchrony between mean arterial pressure and mean cerebral blood flow at rest.
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