Qureshi M Umar, Hill N A
Department of Mathematics, International Islamic University, Sector H10, Islamabad, 44000, Pakistan.
School of Mathematics and Statistics, University of Glasgow, Glasgow, G12 8QW, UK.
J Math Biol. 2015 Dec;71(6-7):1525-49. doi: 10.1007/s00285-015-0867-2. Epub 2015 Mar 10.
Experiments using wave intensity analysis suggest that the pulmonary circulation in sheep and dogs is characterized by negative or open-end type wave reflections, that reduce the systolic pressure. Since the pulmonary physiology is similar in most mammals, including humans, we test and verify this hypothesis by using a subject specific one-dimensional model of the human pulmonary circulation and a conventional wave intensity analysis. Using the simulated pressure and velocity, we also analyse the performance of the P-U loop and sum of squares techniques for estimating the local pulse wave velocity in the pulmonary arteries, and then analyse the effects of these methods on linear wave separation in the main pulmonary artery. P-U loops are found to provide much better estimates than the sum of squares technique at proximal locations, but both techniques accumulate progressive error at distal locations away from heart, particularly near junctions. The pulse wave velocity estimated using the sum of squares method also gives rise to an artificial early systolic backward compression wave. Finally, we study the influence of three types of pulmonary hypertension viz. pulmonary arterial hypertension, chronic thromboembolic pulmonary hypertension and pulmonary hypertension associated with hypoxic lung disease. Simulating these conditions by changing the relevant parameters in the model and then applying the wave intensity analysis, we observe that for each group the early systolic backward decompression wave reflected from proximal junctions is maintained, whilst the initial forward compression and the late systolic backward compression waves amplify with increasing pathology and contribute significantly to increases in systolic pressure.
使用波强度分析的实验表明，绵羊和狗的肺循环具有负向或开放式波反射特征，这会降低收缩压。由于包括人类在内的大多数哺乳动物的肺生理学相似，我们通过使用人类肺循环的个体特异性一维模型和传统的波强度分析来测试和验证这一假设。利用模拟的压力和速度，我们还分析了P-U环和平方和技术在估计肺动脉局部脉搏波速度方面的性能，然后分析了这些方法对主肺动脉线性波分离的影响。结果发现，在近端位置，P-U环比平方和技术能提供更好的估计，但在远离心脏的远端位置，尤其是在分支附近，这两种技术都会累积渐进性误差。使用平方和方法估计的脉搏波速度还会产生一个人为的早期收缩期向后压缩波。最后，我们研究了三种类型的肺动脉高压，即肺动脉高压、慢性血栓栓塞性肺动脉高压和与低氧性肺病相关的肺动脉高压的影响。通过改变模型中的相关参数来模拟这些情况，然后应用波强度分析，我们观察到，对于每组情况，从近端分支反射的早期收缩期向后减压波得以保留，而初始向前压缩波和晚期收缩期向后压缩波随着病变加重而放大，并对收缩压升高有显著贡献。
