Role of tapering in aortic wave reflection: hydraulic and mathematical model study
Role of tapering in aortic wave reflection: hydraulic and mathematical model study
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DOI：
10.1016/s0021-9290(99)00180-3
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发表时间：
2000-03-01
影响因子：
2.4
通讯作者：
Verdonck, P
中科院分区：
文献类型：
--
作者：
Segers, P;Verdonck, P
在解剖上正确的1：1比例的动脉树液压弹性管模型上，沿主动脉的六个位置同时测量了压力和流量。根据(I)四分之一波长公式和(Ii)足对足(c(Ff))和表观相速度(c(App))的比较，我们的结果建议在肾动脉水平上有一个离散的反射点。然而，压力波在所有六个位置的入射波和反射波的分离表明是连续的反射：当正向波经过时，每个位置都会产生一个反射波。我们使用简单的锥形几何结构(长度分别为50 cm、31 mm和11 mm的近端和远端直径)的数学传输线模型对低(0.32毫升/毫米汞柱)、正常(1.6毫升/毫米汞)和高(8毫升/毫米汞)的总动脉顺应性进行了进一步的分析。利用四分之一波长公式，在x=33 cm处发现了一个离散的反射点，即肾动脉的水平，与总顺应值无关。然而。局部分析比较c(Ff)和c(App)没有发现明显的反射位置，而对入射和反射波的分析仅仅表明是连续反射。因此，我们得出结论，体内测量的主动脉波反射指数是至少两个相互作用的现象的结果。由于锥度而产生的连续波反射，以及由横隔膜水平上的分支引起的局部反射。连续反射隐藏在输入阻抗模式中。使用四分之一波长公式或经典的波分离理论，它看起来像是来自单个离散位置的反射，混淆地也位于隔膜水平，因此，应谨慎使用四分之一波长公式和线性波分离理论来识别存在锥度的波反射区，即在大多数哺乳动物动脉中，(C)2000 Elsevier Science Ltd.。
Pressure and flow have been measured simultaneously at six locations along the aorta of an anatomically correct 1:1 scale hydraulic elastic tube model of the arterial tree. Our results suggest a discrete reflection point at the level of the renal arteries based on (i) the quarter-wavelength formula and (ii) the comparison of foot-to-foot (c(ff)) and apparent phase velocity (c(app)). However, separation of the pressure wave into an incident and reflected wave at all six locations indicates continuous reflection: a reflected wave is generated at each location as the forward wave passes by. We did a further analysis using a mathematical transmission line model with a simple tapering geometry (length 50 cm, 31 and 11 mm proximal and distal diameter, respectively) for a low (0.32 ml/mmHg), normal (1.6 ml/mmHg) and high (8 ml/mmHg) value of total arterial compliance. Using the quarter-wavelength formula, a discrete reflection point is found at x = 33 cm, the level of the renal arteries, independent of the value of total compliance. However. local analysis comparing c(ff) and c(app) does not reveal a marked reflection site, and the analysis of incident and reflected waves merely suggests a continuous reflection. We therefore conclude that the measured in vivo aortic wave reflection indices are the result of at least two interacting phenomena. a continuous wave reflection due to tapering, and local reflections arising from branches at the level of the diaphragm. The continuous reflection is hidden in the input impedance pattern. Using the quarter-wavelength formula or the classical wave separation theory, it appears as a reflection coming from a single discrete site, confusingly also located at the level of the diaphragm, Therefore, the quarter-wavelength formula and the linear wave separation theory should be used with caution to identify wave reflection zones in the presence of tapering, i.e., in most mammalian arteries, (C) 2000 Elsevier Science Ltd. All rights reserved.