Valve mediated hemodynamics and their association with distal ascending aortic diameter in bicuspid aortic valve subjects

Abstract

Purpose Valve mediated hemodynamics have been postulated to contribute to pathology of the ascending aorta (AAo). The objective of this study is to assess the association of aortic valve morphology and hemodynamics with downstream AAo size in subjects with bicuspid aortic valve (BAV) disease. Materials and Methods Four‐dimensional flow MRI at 1.5 or 3 Tesla was used to evaluate the hemodynamics in the proximal AAo of 52 subjects: size‐matched controls with tricuspid aortic valves (n = 24, mid ascending aorta [MAA] diameter = 38.0 ± 4.9 mm) and BAV patients with aortic dilatation (n = 14 right and left coronary leaflet fusion [RL]‐BAV, MAA diameter = 38.1 ± 5.3 mm; n = 14 right and noncoronary leaflet fusion [RN]‐BAV, MAA diameter = 36.5 ± 6.6 mm). A validated semi‐automated technique was used to evaluate hemodynamic metrics (flow angle, flow displacement, and jet quadrant) and valve morphology (orifice circularity) for all subjects. Regression analysis of these metrics to AAo diameter was performed. Results RN‐BAV subjects displayed a stronger correlation between hemodynamic metrics in the proximal AAo with diameter in the distal AAo compared with size‐matched tricuspid aortic valve (TAV) controls and RL‐BAV subjects. The distal AAo diameter was found to be strongly correlated to the upstream flow displacement (R2adjusted = 0.75) and flow angle (R2adjusted = 0.66) measured at the sino‐tubular junction (STJ). Orifice circularity was also strongly correlated (R2adjusted = 0.53) to the distal AAo diameter in RN‐BAV subjects. For TAV controls and RL‐BAV subjects, correlations were weaker (R2adjusted < 0.2). Conclusion Hemodynamics in the STJ were strongly correlated to the distal AAo diameter for the RN‐BAV subjects. Hemodynamic metrics were more strongly correlated to the downstream aortic size when compared with valve morphology metrics. Level of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:246–254.

Altered Ascending Aorta Hemodynamics in Patients After Arterial Switch Operation for Transposition of the Great Arteries

“…This study shows that children and adolescent TGA patients after ASO have an eccentric systolic flow in the ascending aorta: regions of most prominent flow eccentricity were detected at the level of the neo‐aortic root and STJ. Consistent with the results of studies in patients with a bicuspid aortic valve, we found a close linear relationship between aortic dimensions and the normalized FD. In one of these studies, systolic FD was correlated with future ascending aortic growth in patients with bicuspid valve anatomy .…”

Pathogenic Mechanisms of Bicuspid Aortic Valve Aortopathy

“…There is extensive evidence that blood flow and shear stress in the tubular ascending aorta are markedly altered by a BAV, even in the absence of significant flow obstruction (Entezari et al, 2014 ; Garcia et al, 2016 ; Cao et al, 2017 ; Raghav et al, 2017 ; Shan et al, 2017 ; Figure 9 ). However, fused-leaflet morphology is not a sole determinant of helicity of blood flow or region of maximal wall stress in the tubular ascending aorta (Raghav et al, 2017 ; Shan et al, 2017 ), as age and clinical characteristics are important (Burris et al, 2016 ; Girdauskas et al, 2016b ; van Ooij et al, 2016 ; Shan et al, 2017 ).…”

“…Aortic dimension has been the most used marker of aortic dissection risk, yet it provides little prognostic information over the clinically important range of 40–55 mm (2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines For the Diagnosis and Management of Patients with Thoracic Aortic Disease Representative, Erbel et al, 2014 ; 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines For the Diagnosis and Management of Patients with Thoracic Aortic Disease Representative Members et al, 2016 ), while the majority of aortic dissections occur at dimensions less than these (Pape et al, 2007 ). This limitation has led to other approaches such as examining morphometry (Biaggi et al, 2009 ; Habchi et al, 2017 ), hemodynamic factors (Atkins et al, 2016 ; DeCampli, 2017 ; Raghav et al, 2017 ), the position and shape of the aneurysm (Schaefer et al, 2008 ; Della Corte et al, 2014b ), aortic growth rate (Elefteriades and Farkas, 2010 ), and aortic distensibility parameters (Benedik et al, 2013 ). To date, observed population-based associations are weak and are unlikely to provide any predictive value for the individual patient.…”

Four-Dimensional Flow Magnetic Resonance Imaging for Cardiovascular Imaging: from Basic Concept to Clinical Application

“…A recent study reported that valve-mediated hemodynamics are even correlated with the distal ascending aorta [67]. Fourdimensional flow MRI can identify the eccentric jet flow in patients with BAV and may help stratify the risk for development of ascending aortic aneurysms and aortic dissection.…”