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Multi-metrics assessment of dynamic cerebral autoregulation in middle and posterior cerebral arteries in young fit women
bioRxiv - Physiology Pub Date : 2020-05-27 , DOI: 10.1101/2020.05.25.114447
Lawrence Labrecque , Audrey Drapeau , Kevan Rahimaly , Sarah Imhoff , François Billaut , Patrice Brassard

Individuals with low orthostatic tolerance show greater decrease in posterior cerebral artery mean blood velocity (PCAvmean). Since young fit women often experience presyncopal symptoms, their posterior cerebral circulation may be prone to greater decreases in PCAvmean, probably explained by an attenuated dynamic cerebral autoregulation (dCA). Regional differences in dCA have never been evaluated in young fit women. We compared dCA in the middle cerebral artery (MCA) and posterior cerebral artery (PCA) in 11 young fit women (25 ± 4y; V̇O2 max: 48.1 ± 4.1 ml x kg-1min-1) in response to a sit-to-stand (5 min sitting followed by 5 min standing) and repeated squat-stand maneuvers performed at 0.05 Hz and 0.10 Hz. The cerebral pressure-flow relationship was characterized using four metrics: 1) percent reduction in blood velocity (BV) per percent reduction in MAP (% BV/% MAP) during initial orthostatic stress (0-15 s after sit-to-stand); 2) onset of the regulatory response (i.e. time delay before an increase in conductance (BV/MAP); 3) rate of regulation (RoR), following sit-to-stand and; 4) transfer function analysis (TFA) of forced MAP oscillations induced by repeated squat-stands. Upon standing, the relative decline in MCAvmean and PCAvmean was similar (-25 ± 9 vs. -30 ± 13%; p=0.29). The onset of the regulatory response (p=0.665), %ΔBV/%ΔMAP (p=0.129) and RoR (p=0.067) were not different between MCA and PCA. In regard to TFA, there was an ANOVA artery effect for gain (p<0.001) and a frequency effect for phase (p<0.001). These findings indicate the absence of regional differences in dCA in young fit women.

中文翻译:

青年女性中脑后动脉动态脑自动调节的多指标评估

体位耐受性低的个体显示大脑后动脉平均血流速度(PCAvmean)下降更大。由于年轻健康的女性经常会出现晕厥前的症状,因此他们的后脑循环可能倾向于PCAvmean更大程度的下降,这可能是由于动态脑自动调节(dCA)减弱所致。从未对年轻健康女性评估dCA的区域差异。我们比较了11位健康的年轻女性(25±4y;V̇O2最大值:48.1±4.1 ml x kg-1min-1)对大脑中动脉(MCA)和大脑后动脉(PCA)的dCA的影响,站立(坐5分钟,然后坐5分钟),然后在0.05 Hz和0.10 Hz下进行重复的深蹲动作。使用四个指标来表征脑压-流量关系:1)初始体位性压力(坐姿后0到15 s)期间MAP降低的百分比(BV / MAP的百分比)引起的血流速度降低百分比;2)调节反应的开始(即电导增加之前的时间延迟(BV / MAP); 3)静坐后的调节率(RoR);以及 4)重复蹲架引起的强制MAP振荡的传递函数分析(TFA)。站立时,MCAvmean和PCAvmean的相对下降幅度相似(-25±9比-30±13%; p = 0.29)。MCA和PCA之间的调节反应(p = 0.665),%ΔBV/%ΔMAP(p = 0.129)和RoR(p = 0.067)的发作无差异。关于TFA,ANOVA动脉对增益有影响(p <0.001),频率对相位有影响(p <0.001)。这些发现表明,年轻健康女性的dCA没有区域差异。
更新日期:2020-05-27
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