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.

A patient-specific lumped-parameter model of coronary circulation

“…Qureshi et al . 18 studied the pressure wave reflections in the pulmonary arteries using the conventional wave intensity analysis and a 1D computational model. It was found that the geometric properties of the pulmonary musculature play an important role in the system.…”

Study of cardiovascular function using a coupled left ventricle and systemic circulation model

“…In our model of the systemic arteries, the pulse wave velocity (PWV) is determined by the pressure–area relationship for the arteries (the tube law), specifically . We have studied the clinical estimates of the PWV in a model of the pulmonary circulation ( Qureshi and Hill, 2015 ). It would be possible in principle to use the clinical estimates of the PWV to assess the tube law although errors in the measurements may make this difficult.…”

A One-Dimensional Hemodynamic Model of the Coronary Arterial Tree

“…To perform the WI analysis, the forward and backward wave fronts of the pressure δpi± and velocity δui± are defined as in Qureshi and Hill (2015):…”

“…Olufsen et al studied such a model for systemic circulation in which a structured tree boundary condition was used (Olufsen, 1999; Olufsen et al, 2000). A 1D model was also developed for subject-specific human pulmonary circulation (Qureshi and Hill, 2015). Similar approaches were used to predict flow and pressure in the pulmonary arteries (Olufsen et al, 2012), which showed that a decrease of the compliance in the large arteries leads to a pressure rise.…”