Impact of modeling fluid-structure interaction in the computational analysis of aortic root biomechanics

Numerical modeling can provide detailed and quantitative information on aortic root (AR) biomechanics, improving the understanding of AR complex pathophysiology and supporting the development of more effective clinical treatments. From this standpoint, fluid-structure interaction (FSI) models are currently the most exhaustive and potentially realistic computational tools. However, AR FSI modeling is extremely challenging and computationally expensive, due to the explicit simulation of coupled AR fluid dynamics and structural response, while accounting for complex morphological and mechanical features. We developed a novel FSI model of the physiological AR simulating its function throughout the entire cardiac cycle. The model includes an asymmetric MRI-based geometry, the description of aortic valve (AV) non-linear and anisotropic mechanical properties, and time-dependent blood pressures. By comparison to an equivalent finite element structural model, we quantified the balance between the extra information and the extra computational cost associated with the FSI approach. Tissue strains and stresses computed through the two approaches did not differ significantly. The FSI approach better captured the fast AV opening and closure, and its interplay with blood fluid dynamics within the Valsalva sinuses. It also reproduced the main features of in vivo AR fluid dynamics. However, the FSI simulation was ten times more computationally demanding than its structural counterpart. Hence, the FSI approach may be worth the extra computational cost when the tackled scenarios are strongly dependent on AV transient dynamics, Valsalva sinuses fluid dynamics in relation to coronary perfusion (e.g. sparing techniques), or AR fluid dynamic alterations (e.g. bicuspid AV).