Hickson Stacey S, Nichols Wilmer W, McDonnell Barry J, Cockcroft John R, Wilkinson Ian B, McEniery Carmel M
Division of Experimental Medicine and Immunotherapeutics, Department of Medicine, University of Cambridge, Cambridge, UK.
Division of Cardiovascular Medicine, Department of Medicine, University of Florida, Gainesville, FL, USA.
Hypertens Res. 2016 Oct;39(10):723-729. doi: 10.1038/hr.2016.64. Epub 2016 Jun 16.
In individuals with compliant aortas, peripheral muscular artery stiffness exceeds central elastic artery stiffness. With aging, central stiffness increases with little change in peripheral stiffness, resulting in a reversal of the normal stiffness gradient. This reversal may reduce the wave reflection amplitude due to the movement of the major 'effective' reflection site further from the heart. To test this phenomenon, we investigated the relationship among arterial stiffness gradients (normal and reversed), wave reflection amplitude and reflection site distance. Subjects aged ⩾50 years were recruited from the Anglo-Cardiff Collaborative Trial. Central stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV). In Study 1, peripheral PWV was also measured in the arm (carotid-radial pulse wave velocity) and, in Study 2, in the leg (femoral-dorsalis pedis). Reflection site distance was calculated from cfPWV and the reflected wave Tr. Subjects were dichotomized into those with a normal stiffness gradient (peripheral >central PWV) or a reversed gradient (peripheral <central PWV). In Study 1, the reflection site distance was greater in subjects with a reversed gradient (P<0.01), whereas time-to-reflection was lower (P<0.001). Both the augmentation pressure (P<0.001) and augmentation index (P<0.05) were greater in subjects with a reversed gradient. In Study 2, the augmentation pressure, augmentation index and reflection site distance were greater in subjects with a reversed stiffness gradient (P<0.01, P<0.05 and P<0.01, respectively), and time-to-reflection was not different between groups. A reversed arterial stiffness gradient is associated with an increased reflection site distance, and a paradoxical increase in reflected wave amplitude and augmentation index.
在主动脉顺应性良好的个体中，外周肌性动脉僵硬度超过中心弹性动脉僵硬度。随着年龄增长，中心僵硬度增加，而外周僵硬度变化不大，导致正常僵硬度梯度发生逆转。这种逆转可能会由于主要“有效”反射部位远离心脏的移动而降低波反射幅度。为了验证这一现象，我们研究了动脉僵硬度梯度（正常和逆转）、波反射幅度与反射部位距离之间的关系。从英-加的夫协作试验中招募了年龄≥50岁的受试者。通过颈股脉搏波速度（cfPWV）评估中心僵硬度。在研究1中，还测量了手臂的外周脉搏波速度（颈-桡脉搏波速度），在研究2中，测量了腿部的外周脉搏波速度（股-足背动脉脉搏波速度）。根据cfPWV和反射波Tr计算反射部位距离。将受试者分为具有正常僵硬度梯度（外周＞中心PWV）或逆转梯度（外周＜中心PWV）的两组。在研究1中，具有逆转梯度的受试者反射部位距离更大（P<0.01），而反射时间更低（P<0.001）。具有逆转梯度的受试者增强压（P<0.001）和增强指数（P<0.05）均更高。在研究2中，具有逆转僵硬度梯度的受试者增强压、增强指数和反射部位距离更大（分别为P<0.01、P<0.05和P<0.01），两组之间的反射时间无差异。动脉僵硬度梯度逆转与反射部位距离增加以及反射波幅度和增强指数的反常增加有关。
