Image-based computational hemodynamics in the right heart.

Characterizing flow within the right heart (RH) is particularly challenging due to its complex geometries. However, gaining insight into RH fluid dynamics is of extreme diagnostic importance, given the high prevalence of acquired and congenital heart diseases with impaired RH function. In this proof-of-concept study, we propose a pipeline for patient-specific simulations of RH hemodynamics. We reconstruct the geometry and motion of the patient's right atrium, ventricle, and pulmonary and tricuspid valves, from multi-series cine MRI. For this purpose, we develop a novel and flexible reconstruction procedure that, for the first time, integrates patient-specific tricuspid valve dynamics into a computational model, enhancing the accuracy of our RH blood flow simulations. We apply this approach to study the hemodynamics in both healthy and repaired-ToF RH with severe pulmonary regurgitation, as well as to assess the hemodynamic changes induced by the pulmonary valve replacement intervention. Modeling the entire RH enables us to understand the contribution of the superior and inferior vena cava inflows to the ventricular filling, as well as the impact of the impaired right atrial function on the ventricular diastole. To analyze the turbulent and transitional behavior, we include the large eddy simulation sigma model in our computational framework, which reveals how the contribution of the smallest scales in the dissipation of the turbulent energy changes among health and disease.