Pulsatile hemodynamics of hypertension: systematic review of aortic input impedance.
Pulsatile hemodynamics of hypertension: systematic review of aortic input impedance.
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DOI：
10.1097/hjh.0b013e328354e81d
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发表时间：
2012-08
影响因子：
4.9
通讯作者：
Ahn AC
中科院分区：
文献类型：
--
作者：
Li W;Ahn AC
输入阻抗是脉动血流的频率依赖性后负荷。输入阻抗的研究早在20世纪60年代就已进行，并已应用于高血压（HTN）。然而，迄今为止，这些研究尚未得到系统评价。本系统综述旨在总结文献，从阻抗理论的角度解释现有数据，并讨论其对HTN产生生理学见解的潜力。我们确定了11项研究，其中报告了HTN和对照组（CNT）的计算阻抗模量。此外，我们对其中3项研究的原始数据进行了双变量分析。主要发现包括：（1）与CNT组相比，HTN组在0 Hz（Z 0）和心率频率（Z1）处的阻抗模量持续升高，阻抗相位首次穿过0的频率（f0）增加，但特征阻抗（Zc）没有一致的模式;（2）收缩压（SBP）、舒张压（DBP）与Z 0、Z1高度相关，与f0中度相关，与Zc相关性较小;（3）Zc的测量和计算方法多种多样且不一致;（4）有相当比例的高血压患者具有“正常”的Z 0、Z1和Zc值。这些发现受到异质性研究人群和小样本量的限制。这些结果表明，Z 0，Z1和f0与高血压显著相关，而Zc的作用不太清楚。需要额外的研究来评估这些输入阻抗变量，以便在临床环境中产生实质性的影响。
Input impedance is the frequency-dependent afterload to pulsatile blood flow. Studies of input impedance have been performed as early as the 1960s and have been applied to hypertension (HTN). However, to date, these studies have not been systematically evaluated. This systematic review aims to summarize the literature, interpret existing data from the perspective of impedance theory, and to discuss their potential for generating physiological insights into HTN. We identified 11 studies where computed impedance moduli from both HTN and control (CNT) groups were reported. In addition, we performed bivariate analyses of raw data from 3 of these studies. Major findings include (1) HTN groups had consistently elevated impedance moduli at 0Hz (Z0) and at heart rate frequency (Z1), an increased frequency where impedance phase first crosses 0 (f0), but no consistent pattern in characteristic impedance (Zc), when compared to CNT groups; (2) systolic (SBP) and diastolic (DBP) blood pressure are highly correlated with Z0 and Z1, moderately correlated with f0, less correlated with Zc; and (3) the measurement and calculation methods for Zc are varied and inconsistent, and (4) a not insignificant proportion of hypertensive subjects have “normal” Z0, Z1 and Zc values. These findings are limited by the heterogeneous study populations and small sample sizes. These findings suggest that Z0, Z1 and f0 are significantly associated with hypertension, while the role of Zc is less clear. Additional studies are needed to evaluate these input impedance variables in order to generate substantial implications in clinic settings.