Fluid–structure interaction modeling of calcific aortic valve disease using patient-specific three-dimensional calcification scans

Abstract

Calcific aortic valve disease (CAVD) is characterized by calcification accumulation and thickening of the aortic valve cusps, leading to stenosis. The importance of fluid flow shear stress in the initiation and regulation of CAVD progression is well known and has been studied recently using fluid-structure interaction (FSI) models. While cusp calcifications are three-dimensional (3D) masses, previously published FSI models have represented them as either stiffened or thickened two-dimensional (2D) cusps. This study investigates the hemodynamic effect of these calcifications employing FSI models using 3D patient-specific calcification masses. A new reverse calcification technique (RCT) is used for modeling different stages of calcification growth based on the spatial distribution of calcification density. The RCT is applied to generate the 3D calcification deposits reconstructed from a patient-specific CT scans. Our results showed that consideration of 3D calcification deposits led to both higher fluid shear stresses and unique fluid shear stress distribution on the aortic side of the cusps that may have an impact on the calcification growth rate. However, the flow did not seem to affect the geometry of the calcification during the growth phase.

Image-Guided Fluid-Structure Interaction Simulation of Transvalvular Hemodynamics: Quantifying the Effects of Varying Aortic Valve Leaflet Thickness

“…Nevertheless, the reported numerical results for the peak flow velocity and the aortic orifice area were shown to be consistent with those seen in clinical observations, [38,39]. Remarkably, our results with a simple model of the valve calcification, but a more realistic model of aorta, were also consistent with the clinical observations reported in [13]. In our simulations the peak flow velocity is ranging 1.4-3.3 (m/s) and the aortic orifice area is ranging 4.3-1.3 (cm 2 ), depending on the valve thickness h 1 − h 3 .…”

“…In our simulations the peak flow velocity is ranging 1.4-3.3 (m/s) and the aortic orifice area is ranging 4.3-1.3 (cm 2 ), depending on the valve thickness h 1 − h 3 . In the clinical observations [13], the peak flow velocity is ranging from < 2 (m/s) to 3-3.9 (m/s) and the aortic orifice is ranging from 3.9 ± 1.2 (m/s) to 1.0-1.5 cm 2 for healthy and moderate stenosis, respectively. The agreement of those two sets of results with clinical observations can be considered to be partial validation for both the results presented in [13] and those presented in this work.…”

“…In the clinical observations [13], the peak flow velocity is ranging from < 2 (m/s) to 3-3.9 (m/s) and the aortic orifice is ranging from 3.9 ± 1.2 (m/s) to 1.0-1.5 cm 2 for healthy and moderate stenosis, respectively. The agreement of those two sets of results with clinical observations can be considered to be partial validation for both the results presented in [13] and those presented in this work. A better (or full) validation would need to relate to measurements corresponding to one specific patient and the numerical results that are based on a model correctly representing all essential features of that patient anatomy and disease, which include both the real aorta and advanced calcification model (if calcification is the problem).…”

“…A fluid-structure interaction solution with more realistic model of aortic valve calcification was reported in [13]. However, in [13], aorta was simplified to be in the shape of circular cylinder, and no supra-aortic branches were considered.…”

“…A fluid-structure interaction solution with more realistic model of aortic valve calcification was reported in [13]. However, in [13], aorta was simplified to be in the shape of circular cylinder, and no supra-aortic branches were considered. Nevertheless, the reported numerical results for the peak flow velocity and the aortic orifice area were shown to be consistent with those seen in clinical observations, [38,39].…”