Diabetes and Vascular Medicine Research Centre, National Institute of Health Research Exeter Clinical Research Facility, University of Exeter Medical School , Exeter , United Kingdom.
Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa , Pisa , Italy.
J Appl Physiol (1985). 2018 Jan 1;124(1):150-159. doi: 10.1152/japplphysiol.00310.2017. Epub 2017 Sep 21.
Wall shear rate (WSR) is an important stimulus for the brachial artery flow-mediated dilation (FMD) response. However, WSR estimation near the arterial wall by conventional Doppler is inherently difficult. To overcome this limitation, we utilized multigate Doppler to accurately determine the WSR stimulus near the vessel wall simultaneously with the FMD response using an integrated FMD system [Ultrasound Advanced Open Platform (ULA-OP)]. Using the system, we aimed to perform a detailed analysis of WSR-FMD response and establish novel WSR parameters in a healthy young population. Data from 33 young healthy individuals (27.5 ± 4.9 yr, 19 females) were analyzed. FMD was assessed with reactive hyperemia using ULA-OP. All acquired raw data were postprocessed using custom-designed software to obtain WSR and diameter parameters. The acquired velocity data revealed that nonparabolic flow profiles within the cardiac cycle and under different flow states, with heterogeneity between participants. We also identified seven WSR magnitude and four WSR time-course parameters. Among them, WSR area under the curve until its return to baseline was the strongest predictor of the absolute ( R = 0.25) and percent ( R = 0.31) diameter changes in response to reactive hyperemia. For the first time, we identified mono- and biphasic WSR stimulus patterns within our cohort that produced different magnitudes of FMD response [absolute diameter change: 0.24 ± 0.10 mm (monophasic) vs. 0.17 ± 0.09 mm (biphasic), P < 0.05]. We concluded that accurate and detailed measurement of the WSR stimulus is important to comprehensively understand the FMD response and that this advance in current FMD technology could be important to better understand vascular physiology and pathology. NEW & NOTEWORTHY An estimation of wall shear rate (WSR) near the arterial wall by conventional Doppler ultrasound is inherently difficult. Using a recently developed integrated flow-mediated dilation ultrasound system, we were able to accurately estimate WSR near the wall and identified a number of novel WSR variables that may prove to be useful in the measurement of endothelial function, an important biomarker of vascular physiology and disease.
壁面切变率（WSR）是肱动脉血流介导扩张（FMD）反应的重要刺激因素。然而，传统多普勒技术在动脉壁附近估计 WSR 存在固有困难。为了克服这一限制，我们利用多门控多普勒技术，通过集成的 FMD 系统[超声高级开放平台（ULA-OP）]，同时准确地确定血管壁附近的 WSR 刺激和 FMD 反应。使用该系统，我们旨在对健康年轻人群中的 WSR-FMD 反应进行详细分析，并建立新的 WSR 参数。对 33 名年轻健康个体（27.5±4.9 岁，19 名女性）的数据进行了分析。使用 ULA-OP 通过反应性充血评估 FMD。使用定制设计的软件对所有采集的原始数据进行后处理，以获得 WSR 和直径参数。采集到的速度数据显示，在心动周期内和不同的流动状态下，非抛物线流型，参与者之间存在异质性。我们还确定了 7 个 WSR 幅度和 4 个 WSR 时程参数。其中，WSR 曲线下面积直到其回到基线是反应性充血引起的绝对（ R=0.25）和百分比（ R=0.31）直径变化的最强预测因子。我们首次在我们的队列中确定了单峰和双峰 WSR 刺激模式，它们产生不同幅度的 FMD 反应[绝对直径变化：0.24±0.10 mm（单峰）与 0.17±0.09 mm（双峰），P <0.05]。我们得出结论，准确和详细的 WSR 刺激测量对于全面了解 FMD 反应很重要，并且当前 FMD 技术的这一进步对于更好地理解血管生理学和病理学可能很重要。
使用传统多普勒超声技术，对动脉壁附近的壁面切变率（WSR）进行估计固有困难。使用最近开发的集成血流介导扩张超声系统，我们能够准确地估计壁面附近的 WSR，并确定了一些新的 WSR 变量，这些变量可能在测量内皮功能方面很有用，内皮功能是血管生理学和疾病的一个重要生物标志物。
