The Reverse Calcification Technique and its Impact on Fluid–Structure Interaction and Transcatheter Replacement Simulations in Bicuspid Aortic Valve

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Calcific aortic valve disease (CAVD) is characterized by stiffened aortic valve leaflets, which rapidly leads to aortic stenosis (AS). Bicuspid Aortic Valve (BAV) is a congenital heart disease, where the valve is composed of two leaflets. Half of the patients with diagnosed AS has a BAV. Our group has previously introduced a novel method, termed Reverse Calcification Technique (RCT). It generates spatial calcified densities from computed tomography (CT) scans of pre-intervention AS patients. The RCT is capable of predicting the CAVD progression that leads to the current stage. Transcatheter aortic valve replacement (TAVR) is a treatment approach for CAVD where a stent with mounted bioprosthetic valve is deployed on the stenotic valve. The off-label use of TAVR within calcified BAV patients raise concerns stemming from the asymmetrical structure of the BAV, which can cause partial anchoring and paravalvular leakage (PVL).

This study aims to extend the RCT for predicting CAVD progression in calcified BAVs. In addition, fluid–structure interaction (FSI) simulations were employed to investigate the hemodynamics of the calcified BAV, followed by refined computational models of the deployments of self and balloon-expandable TAVR devices inside the calcified BAV. The PVL was also calculated by CFD simulations. CT scan of severely stenotic BAV patient was acquired. The RCT was employed to generate the 3D calcification deposits for several stages of the disease. The 3D calcium deposits were embedded inside a parametric model of the BAV. FSI simulations of the calcified BAV were conducted, together with deployment simulations of the Evolut R, PRO and Sapien 3 inside the calcified BAV. The Evolut stent was characterized in asymmetric and elliptic deployment, with lower anchoring forces compared with the Sapien 3. The Sapien 3 and Evolut PRO had comparable PVL values, reduced in half compared with the Evolut R. The proposed biomechanical computational models are a step towards patient-specific simulations to improve future treatment in BAV patients.