Haemodynamic assessment of bicuspid aortic valve aortopathy: a systematic review of the current literature

Abstract

Both genetic and haemodynamic theories explain the aetiology, progression and optimal management of bicuspid aortic valve aortopathy. In recent years, the haemodynamic theory has been explored with the help of magnetic resonance imaging and computational fluid dynamics. The objective of this review was to summarize the findings of these investigations with focus on the blood flow pattern and associated variables, including flow eccentricity, helicity, flow displacement, cusp opening angle, systolic flow angle, wall shear stress (WSS) and oscillatory shear index. A structured literature review was performed from January 1990 to January 2018 and revealed the following 3 main findings: (i) the bicuspid aortic valve is associated with flow eccentricity and helicity in the ascending aorta compared to healthy and diseased tricuspid aortic valve, (ii) flow displacement is easier to obtain than WSS and has been shown to correlate with valve morphology and type of aortopathy and (iii) the stenotic bicuspid aortic valve is associated with elevated WSS along the greater curvature of the ascending aorta, where aortic dilatation and aortic wall thinning are commonly found. We conclude that new haemodynamic variables should complement ascending aorta diameter as an indicator for disease progression and the type and timing of intervention. WSS describes the force that blood flow exerts on the vessel wall as a function of viscosity and geometry of the vessel, making it a potentially more reliable marker of disease progression.

NOTCH Signaling in Aortic Valve Development and Calcific Aortic Valve Disease

“…These observations support that BAV-asociated CAVD has a developmental origin, and its postnatal stenotic progression by calcification is triggered by external stimuli as a second hit after the primary structural defect in utero (9). In support of this view of the pathogenesis of CAVD, the developmental defect of the aortic valve can cause abnormal flow dynamics and thereby predispose the valve to endothelial dysfunction and inflammatory activation, leading to earlier calcification in adulthood (9,(15)(16)(17)(18). Therefore, better understanding of molecular mechanisms regulating aortic valve development, as well as postnatal aortic valve homeostasis, is required for the development of new therapeutic strategies for CAVD.…”

Bicuspid aortic valve morphology and aortic valvular outflow jets: an experimental analysis using an MRI-compatible pulsatile flow circulation system

“…It has been recognized that BAV morphology, categorized according to the bicuspid fusion pattern and number of raphes 23 , affects the natural history of aortopathy in BAV 24 , 25 . Recent advances in 4D-flow MRI have suggested that outflow jet eccentricity is a potential index for the aortopathy phenotype in BAV; it was reported that type 3 aortopathy (involving the aortic arch) was more common in the right and non-coronary cusp fusion phenotype (RN-BAV), whereas type 2 aortopathy (dilatation in the ascending aorta) was more frequent in the right and left coronary cusp fusion phenotype (RL-BAV) 14 , 26 , 27 . However, due to the anatomical varieties and hemodynamic differences among patients clinically, the relationship between BAV morphology and characteristics of the aortic valvular outflow jet has not been determined.…”

The effects of age at correction of aortic coarctation and recurrent obstruction on adolescent patients: MRI evaluation of wall shear stress and pulse wave velocity

“…This result should be interpreted with caution, since no correlation was found within the entire patient group nor in the BAV subgroup. The absence of a comparable correlation for these groups may be explained by the abnormal haemodynamics of BAV patients [25], potentially resulting in different disease progressions for both aortic valve morphologies. Therefore, the significant finding in the TAV subgroup (notably, smaller in size than BAV subgroup) represents an evaluation of the CoA correction for patients selected on valve morphology.…”