Legarth J, Thorup E
Department of Obstetrics and Gynaecology, Herlev Hospital, University of Copenhagen, Denmark.
Scand J Clin Lab Invest. 1989 Sep;49(5):451-7. doi: 10.1080/00365518909089121.
In order to study the indices describing the flow-velocity curves a cardiovascular in vitro model has been constructed. The model consists of two parts: (i) A heart simulator producing controllable cardiac output, pulse rate and pressure variations, (ii) a circulatory system made of elastic butyl rubber tubes with adjustable peripheral resistance bed. The flow-velocity curves were obtained by a Doppler velocity meter as a function of the pulse rate (PR) when pressure, volumetric flow, and peripheral resistances were constant. The four evaluated indices, pulsatility index (PI), peak velocity (Vpeak), rising slope (RS) and A/B ratio (A/B i.e. maximum/minimum velocity ratio) all showed significant correlation with pulse rate. PI, A/B and Vpeak showed a marked increased at low pulse rate and the inverse relation between these indices and pulse rate were best described by power functions, whereas RS was found to be inversely proportional to pulse rate. The results are in good agreement with the few existing clinical observations, and we suggest that the relations described are taken into consideration in the clinical interpretation of blood velocity indices.
为了研究描述血流速度曲线的指标，构建了一个心血管体外模型。该模型由两部分组成：（i）一个心脏模拟器，可产生可控的心输出量、脉搏率和压力变化；（ii）一个由弹性丁基橡胶管制成的循环系统，带有可调节的外周阻力床。当压力、体积流量和外周阻力恒定时，通过多普勒速度仪获得血流速度曲线作为脉搏率（PR）的函数。所评估的四个指标，搏动指数（PI）、峰值速度（Vpeak）、上升斜率（RS）和A/B比值（A/B即最大/最小速度比值）均与脉搏率显示出显著相关性。PI、A/B和Vpeak在低脉搏率时显著增加，这些指标与脉搏率之间的反比关系用幂函数描述最佳，而RS与脉搏率成反比。结果与现有的少数临床观察结果高度一致，我们建议在血流速度指标的临床解释中考虑所描述的关系。
