title: A computational study of pressure wave reflections in the pulmonary arteries.
abstract: 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.
authors.affiliation: Department of Mathematics, International Islamic University, Sector H10, Islamabad, 44000, Pakistan. muquresh@ncsu.edu.|School of Mathematics and Statistics, University of Glasgow, Glasgow, G12 8QW, UK. muquresh@ncsu.edu.
authors.forename: M Umar
authors.initials: MU
authors.lastname: Qureshi
authors.affiliation: School of Mathematics and Statistics, University of Glasgow, Glasgow, G12 8QW, UK. Nicholas.Hill@glasgow.ac.uk.
authors.forename: N A
authors.initials: NA
authors.lastname: Hill
mesh_terms: D000465:Algorithms; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003198:Computer Simulation; D004285:Dogs; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology; D055641:Mathematical Concepts; D008955:Models, Cardiovascular; D011651:Pulmonary Artery / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology; D063177:Pulse Wave Analysis; D034561:Sheep, Domestic
keywords: Numerical simulations; Pulmonary arteries; Pulmonary hypertension; Pulse wave velocity; Wave intensity analysis; Wave reflections