Abstract

Transcatheter aortic valve replacement (TAVR) has emerged as an alternative treatment for inoperable and high risk patients with severe symptomatic aortic stenosis. TAVR short and medium term results are very promising, however paravalvular leak (PVL) post-TAVR still represents a significant complication. PVL post-TAVR is shown to be an independent predictor of short-term and long-term mortality. Despite, its importance and prevalence, with a wide range of reported incidences, only few studies addressed the PVL after TAVR.

In the present study, first, the mathematical lumped parameter model is used to model the simplified circulatory system in presence of PVL and to evaluate the performance of TAVR by computing the variation of the left ventricle stroke work (LVSW) under several pre-TAVR and post-TAVR conditions. Results show that in a large majority of cases, TAVR significantly reduced LVSW. However, in cases with pre-existing aortic stenosis conditions with trace/mild aortic regurgitation, it did not significantly reduce LVSW or even led to an increase.

Second, a three-dimensional (3D) computational fluid dynamics (CFD) simulation is performed in order to investigate the effect of PVL on the diastolic flow-field characteristics post-TAVR. Results show that PVL leads to significant disturbances in blood flow, which characterized by high speed jets, coherent structures and markedly elevated shear stress on both sides of the implanted aortic leaflets, which could promote a more rapid degeneration of the valve leaflets.

Results could be useful in understating the hemodynamics of PVL post-TAVR and estimating some important parameters, which could not be obtained during the medical assessment (e.g. wall shear stress). Also, they could be a help in the process of choosing the appropriate valve for TAVR procedure, based on comparing the pre and post TAVR different scenarios.