Sensitivity Analysis of a Hemodynamic-based Model for Thrombus Formation and Growth

Aortic dissection is a severe cardiovascular disease caused by the occurrence of a tear in the aortic wall. As a result, the blood penetrates the wall and makes a new blood channel called falselumen. The hemodynamic conditions in the false lumen may contribute to the formation of thrombi, which influence the patient diagnosis and outcomes. In this study, the focus is on a hemodynamic-based modelof thrombus formation. Since the model construction presents sources of uncertainties in the model parameter, a variance-based sensitivity analysis is performed. Thrombus formation at abackwards-facing step is considered as a benchmarkfor the numerical simulations and sensitivity analysis.This geometry is capable of representing the main contributions of the model in thrombus formation.The study aims not only at getting a better insight into the model’s structurebut also at preparing model simplifications with the aim of future patient-specific simulations. Apolynomial chaos expansion is employed as a surrogate model, from which the derivation of quantitative sensitivity indices is enhanced. In this study, nine model parametersare selected,whoseactualvaluesarenot well known. The model responsestaken into account are the maximum volume fraction of thrombosis, its time development, and the thrombus growth rate. The results show that the model lends itselfto model reduction since some of the model parameters show little to no influence on the model’s outputs. A thresholdvaluerelated to the concentration of bounded platelets is identified as the key input parameter dominating the model predictions in the current geometry.