Cheng Cynthia, Daskalakis Constantine, Falkner Bonita
Department of Family and Community Medicine, Thomas Jefferson University.
J Vis Exp. 2013 Jan 29(71):e50008. doi: 10.3791/50008.
The authors have utilized capillaroscopy and forearm blood flow techniques to investigate the role of microvascular dysfunction in pathogenesis of cardiovascular disease. Capillaroscopy is a non-invasive, relatively inexpensive methodology for directly visualizing the microcirculation. Percent capillary recruitment is assessed by dividing the increase in capillary density induced by postocclusive reactive hyperemia (postocclusive reactive hyperemia capillary density minus baseline capillary density), by the maximal capillary density (observed during passive venous occlusion). Percent perfused capillaries represents the proportion of all capillaries present that are perfused (functionally active), and is calculated by dividing postocclusive reactive hyperemia capillary density by the maximal capillary density. Both percent capillary recruitment and percent perfused capillaries reflect the number of functional capillaries. The forearm blood flow (FBF) technique provides accepted non-invasive measures of endothelial function: The ratio FBF(max)/FBF(base) is computed as an estimate of vasodilation, by dividing the mean of the four FBF(max) values by the mean of the four FBFbase values. Forearm vascular resistance at maximal vasodilation (FVR(max)) is calculated as the mean arterial pressure (MAP) divided by FBF(max). Both the capillaroscopy and forearm techniques are readily acceptable to patients and can be learned quickly. The microvascular and endothelial function measures obtained using the methodologies described in this paper may have future utility in clinical patient cardiovascular risk-reduction strategies. As we have published reports demonstrating that microvascular and endothelial dysfunction are found in initial stages of hypertension including prehypertension, microvascular and endothelial function measures may eventually aid in early identification, risk-stratification and prevention of end-stage vascular pathology, with its potentially fatal consequences.
作者利用毛细血管显微镜检查和前臂血流技术来研究微血管功能障碍在心血管疾病发病机制中的作用。毛细血管显微镜检查是一种用于直接观察微循环的非侵入性、相对廉价的方法。通过将闭塞后反应性充血诱导的毛细血管密度增加（闭塞后反应性充血毛细血管密度减去基线毛细血管密度）除以最大毛细血管密度（在被动静脉闭塞期间观察到）来评估毛细血管募集百分比。灌注毛细血管百分比表示所有存在的毛细血管中被灌注（功能活跃）的比例，通过将闭塞后反应性充血毛细血管密度除以最大毛细血管密度来计算。毛细血管募集百分比和灌注毛细血管百分比都反映了功能性毛细血管的数量。前臂血流（FBF）技术提供了公认的内皮功能非侵入性测量方法：通过将四个FBF(max)值的平均值除以四个FBF(base)值的平均值来计算FBF(max)/FBF(base)比值，作为血管舒张的估计值。最大血管舒张时的前臂血管阻力（FVR(max)）计算为平均动脉压（MAP）除以FBF(max)。毛细血管显微镜检查和前臂技术都很容易被患者接受，并且可以很快学会。使用本文所述方法获得的微血管和内皮功能测量值可能在临床患者心血管风险降低策略中具有未来应用价值。正如我们已发表的报告所示，在包括高血压前期在内的高血压初始阶段就发现了微血管和内皮功能障碍，微血管和内皮功能测量值最终可能有助于早期识别、风险分层和预防具有潜在致命后果的终末期血管病变。
