Silva Thiago O C, Sales Allan R K, Araujo Gustavo S M, Fonseca Guilherme W P, Braga Pedro G S, Faria Diego, Rocha Helena N M, Rocha Natalia G, Lima Marta F, Mady Charles, Negrão Carlos E, Alves Maria Janieire N N
Heart Institute, University of São Paulo Medical School, São Paulo, Brazil.
D'OR Institute for Research and Education, São Paulo, Brazil.
Front Physiol. 2021 Mar 11;12:629674. doi: 10.3389/fphys.2021.629674. eCollection 2021.
Disturbed blood flow, characterized by high retrograde and oscillatory shear rate (SR), is associated with a proatherogenic phenotype. The impact of disturbed blood flow in patients with heart failure with reduced ejection fraction (HFrEF) remains unknown. We tested the hypothesis that acute elevation to retrograde and oscillatory SR provoked by local circulatory occlusion would increase endothelial microparticles (EMPs) and decrease brachial artery flow-mediated dilation (FMD) in patients with HFrEF.
Eighteen patients with HFrEF aged 55 ± 2 years, with left ventricular ejection fraction (LVEF) 26 ± 1%, and 14 control subjects aged 49 ± 2 years with LVEF 65 ± 1 randomly underwent experimental and control sessions. Brachial artery FMD (Doppler) was evaluated before and after 30 min of disturbed forearm blood flow provoked by pneumatic cuff (Hokanson) inflation to 75 mm Hg. Venous blood samples were collected at rest, after 15 and 30 min of disturbed blood flow to assess circulating EMP levels (CD42b-/CD31+; flow cytometry).
At rest, FMD was lower in patients with HFrEF compared with control subjects ( < 0.001), but blood flow patterns and EMPs had no differences ( > 0.05). The cuff inflation provoked a greater retrograde SR both groups ( < 0.0001). EMPs responses to disturbed blood flow significantly increased in patients with HFrEF ( = 0.03). No changes in EMPs were found in control subjects ( > 0.05). Disturbed blood flow decreased FMD both groups. No changes occurred in control condition.
Collectively, our findings suggest that disturbed blood flow acutely decreases FMD and increases EMP levels in patients with HFrEF, which may indicate that this set of patients are vulnerable to blood flow disturbances.
以高逆行性和振荡性剪切速率（SR）为特征的血流紊乱与动脉粥样硬化前表型相关。射血分数降低的心力衰竭（HFrEF）患者中血流紊乱的影响尚不清楚。我们检验了这样一个假设，即局部循环阻塞引起的逆行性和振荡性SR急性升高会增加HFrEF患者的内皮微粒（EMP）并降低肱动脉血流介导的扩张（FMD）。
18例年龄55±2岁、左心室射血分数（LVEF）为26±1%的HFrEF患者和14例年龄49±2岁、LVEF为65±1%的对照受试者随机接受实验和对照实验。在通过气动袖带（Hokanson）充气至75 mmHg引发前臂血流紊乱30分钟前后，评估肱动脉FMD（多普勒）。在静息状态下、血流紊乱15分钟和30分钟后采集静脉血样本，以评估循环EMP水平（CD42b-/CD31+；流式细胞术）。
静息时，HFrEF患者的FMD低于对照受试者（<0.001），但血流模式和EMP无差异（>0.05）。袖带充气使两组的逆行性SR均显著增加（<0.0001）。HFrEF患者中，EMP对血流紊乱的反应显著增加（=0.03）。对照受试者中未发现EMP有变化（>0.05）。血流紊乱使两组的FMD均降低。在对照条件下未发生变化。
总体而言，我们的研究结果表明，血流紊乱会使HFrEF患者的FMD急性降低并使EMP水平升高，这可能表明这组患者易受血流紊乱影响。
