Sensitivity analysis to haemodynamic boundary conditions in human coronary arteries

Abstract

Advances in medical imaging and computational power have led to the emergence of patient-specific computational modelling for non-invasive coronary stenosis severity assessment. Computational fluid dynamics (CFD) models are usually complex and expensive regarding the computational cost and the time required to create them, which does not satisfy clinicians’ requirements of accuracy and speed. In the case of coronary artery disease (CAD), there has been a lack of consensus on how to create high fidelity models to support the assessment of predictive applications based on haemodynamic indices and plaque characterization in order to provide personalized risk assessment, disease detection and progression to further guide therapy. Nowadays, fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are the two invasive methods mainly used to measure coronary stenosis severity. CFD is currently being used commercially to measure FFR indices non-invasively. Despite this, a thorough study regarding the haemodynamic boundary conditions to these CFD simulations constitute a necessary requirement to determine the model fidelity towards reproducing a physiological scenario. Furthermore, a 3-D computational assessment of iFR has never been done. The objective of this work was to asses the impact of boundary conditions and geometry on the blood flow dynamics of patients with coronary artery disease. A sensitivity analysis was conducted by creating computational models with different boundary conditions and anatomical differences, i.e., with and without including the aorta. Special focus was given to haemodynamic parameters, such as FFR and iFR. Results demonstrate the influence of the presence of the aorta, which is necessary to reproduce the effect of the arterial system, and therefore physiological pressure values. Furthermore, results also show the potential of the iFR as a new in-silico approach for non-invasive stenosis severity assessment using transient simulations.