Influence of model boundary conditions on blood flow patterns in a patient specific stenotic right coronary artery

Abstract

BackgroundIn literature, the effect of the inflow boundary condition was investigated by examining the impact of the waveform and the shape of the spatial profile of the inlet velocity on the cardiac hemodynamics. However, not much work has been reported on comparing the effect of the different combinations of the inlet/outlet boundary conditions on the quantification of the pressure field and flow distribution patterns in stenotic right coronary arteries.MethodNon-Newtonian models were used to simulate blood flow in a patient-specific stenotic right coronary artery and investigate the influence of different boundary conditions on the phasic variation and the spatial distribution patterns of blood flow. The 3D geometry of a diseased artery segment was reconstructed from a series of IVUS slices. Five different combinations of the inlet and the outlet boundary conditions were tested and compared.ResultsThe temporal distribution patterns and the magnitudes of the velocity, the wall shear stress (WSS), the pressure, the pressure drop (PD), and the spatial gradient of wall pressure (WPG) were different when boundary conditions were imposed using different pressure/velocity combinations at inlet/outlet. The maximum velocity magnitude in a cardiac cycle at the center of the inlet from models with imposed inlet pressure conditions was about 29% lower than that from models using fully developed inlet velocity data. Due to the fact that models with imposed pressure conditions led to blunt velocity profile, the maximum wall shear stress at inlet in a cardiac cycle from models with imposed inlet pressure conditions was about 29% higher than that from models with imposed inlet velocity boundary conditions. When the inlet boundary was imposed by a velocity waveform, the models with different outlet boundary conditions resulted in different temporal distribution patterns and magnitudes of the phasic variation of pressure. On the other hand, the type of different boundary conditions imposed at the inlet and the outlet did not have significant effect on the spatial distribution patterns of the PD, the WPG and the WSS on the lumen surface, regarding the locations of the maximum and the minimum of each quantity.ConclusionsThe observations from this study indicated that the ways how pressure and velocity boundary conditions are imposed in computational models have considerable impact on flow velocity and shear stress predictions. Accuracy of in vivo measurements of blood pressure and velocity is of great importance for reliable model predictions.

Computational prediction of hemodynamical and biomechanical alterations induced by aneurysm dilatation in patient‐specific ascending thoracic aortas

“…The literature shows that the pressure and velocity boundary conditions used in the computational models have an impact on flow velocity and shear stress predictions. Hence, the accuracy of in vivo measurements of blood pressure and velocity is of great importance for reliable model predictions . Since in our study we have used the same velocity profiles to evaluate the hemodynamic descriptors for various stages of aneurysm progression, this may be the reason for a larger athero‐susceptible surface area in healthy subject than the patient.…”

Hemodynamic Interference of Serial Stenoses and Its Impact on FFR and iFR Measurements

“…In addition, the impeded flow from guiding catheter might also alter velocity and pressure fields [30]. The dynamic outlet boundary condition will be more appropriate [37] for quantifying the hemodynamic interference and its clinical measurements. Despite these simplifications, the present work demonstrated a novel way to define the hemodynamic interference and to evaluate the measurement accuracy of both FFR and iFR, which may have significant clinical implications for diagnosis and treatment decisions of serial stenosis.…”

Virtual FFR Quantified with a Generalized Flow Model Using Windkessel Boundary Conditions

“…Since the processed image treated corresponds to a left coronary artery, we used sinusoidal functions to approach the inlet flow distribution into the left coronary artery. e shape of this function is well known (see [6]). Considering that T sys is the period of systole, t s the start of the systolic phase of the current cardiac cycle, and t d the start of the diastolic phase, this periodic function I(t) can be written as follows:…”

“…In the case where the study aims at comparing the results to in vivo measurements, the inlet boundary condition should be adequately chosen. Many works explored the effect of the inlet boundary condition; among them, Liu et al [6] and Taylor and Steinman [7] presented realistic forms of inlet boundary condition in the case of coronary blood flow. Concerning the outlet, the most common boundary condition for blood flow corresponds to a constant pressure.…”