Bicuspid aortic valve aortopathies: An hemodynamics characterization in dilated aortas

Abstract

Bicuspid aortic valve (BAV) aortopathy remains of difficult clinical management due to its heterogeneity and further assessment of related aortic hemodynamics is necessary. The aim of this study was to assess systolic hemodynamic indexes and wall stresses in patients with diverse BAV phenotypes and dilated ascending aortas. The aortic geometry was reconstructed from patient-specific images while the aortic valve was generated based on patient-specific measurements. Physiologic material properties and boundary conditions were applied and fully coupled fluid-structure interaction (FSI) analysis were conducted. Our dilated aortic models were characterized by the presence of abnormal hemodynamics with elevated degrees of flow skewness and eccentricity, regardless of BAV morphotype. Retrograde flow was also present. Both features, predicted by flow angle and flow reversal ratios, were consistently higher than those reported for non-dilated aortas. Right-handed helical flow was present, as well as elevated wall shear stress (WSS) on the outer ascending aortic wall. Our results suggest that the abnormal flow associated with BAV may play a role in aortic enlargement and progress it further on already dilated aortas.

Biomechanical Assessment of Bicuspid Aortic Valve Phenotypes: A Fluid–Structure Interaction Modelling Approach

“…Dimensions employed for all models are presented in Table 1 and displayed in Figure 2, based on clinical measurements [21], consistent with other aortic valve studies [22], and previous BAV models [9,15,23]. As per previous studies [24,25], the geometry of interest was the thoracic aorta, including aortic root, ascending aorta and aortic arch, with the model subsequently truncated at the descending aorta (Figure 3). The same diameter was assumed for ascending and descending aortas.…”

“…WSS is an important vascular regulator that can induce vascular remodelling by directly influencing endothelial cell function [66]. This then contributes towards aortic wall degeneration, associated with aortic dissection [67] and dilation [67,68] and present in BAV patients [69]. Therefore, increased WSS in the ascending aorta may anticipate the onset of aortopathy and contribute to its triggering [24]; which is consistent with our present results that suggest increases in the average WSS along the ascending wall of aorta (measured at three distinct cross-sections along the wall of the ascending aorta).…”

Computational fluid dynamics of the right atrium: Assessment of modelling criteria for the evaluation of dialysis catheters

“…Previous clinical [57] and computational [58,59] studies have linked abnormal flow with high WSS, as well as different WSS distributions, in the ascending aorta. Abnormally high WSS has, in fact, been assumed as a trigger for aortic dilation in congenital diseases by changing the wall tissue mechanical properties [60][61][62].…”

A Fluid–Structure Interaction Study of Different Bicuspid Aortic Valve Phenotypes Throughout the Cardiac Cycle

“…The force, velocity, and displacement at the interface could be exchanged by interpolation of adjacent nodes, which means that the fluid nodes do not need to coincide with the solid grid at the interface. IBM method had been demonstrated to be effective for FSI problems with large deformation ( Marom, 2015 ; Bavo et al, 2016 ; Oliveira et al, 2019 ).…”