AUTHOR=Geeraert Patrick , Jamalidinan Fatemehsadat , Burns Fiona , Jarvis Kelly , Bristow Michael S. , Lydell Carmen , Hidalgo Tobon Silvia S. , de Celis Alonso Benito , Fedak Paul W. M. , White James A. , Garcia Julio 

TITLE=Hemodynamic Assessment in Bicuspid Aortic Valve Disease and Aortic Dilation: New Insights From Voxel-By-Voxel Analysis of Reverse Flow, Stasis, and Energetics

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.725113

DOI=10.3389/fbioe.2021.725113

ISSN=2296-4185

ABSTRACT=<p><bold>Objectives:</bold> Clinical management decisions surrounding ascending aorta (AAo) dilation in bicuspid aortic valve (BAV) disease benefit from personalized predictive tools. 4D-flow MRI may provide patient-specific markers reflective of BAV-associated aortopathy. This study aims to explore novel 4D-flow MRI parametric voxel-by-voxel forward flow, reverse flow, kinetic energy and stasis in BAV disease. We hypothesize that novel parametric voxel-by-voxel markers will be associated with aortic dilation and referral for surgery and can enhance our understanding of BAV hemodynamics beyond standard metrics.</p><p><bold>Methods:</bold> A total of 96 subjects (73 BAV patients, 23 healthy controls) underwent MRI scan. Healthy controls had no known cardiovascular disease. Patients were clinically referred for AAo dilation assessment. Indexed diameters were obtained by dividing the aortic diameter by the patient’s body surface area. Patients were followed for the occurrence of aortic surgery. 4D-flow analysis was performed by a single observer in five regions: left ventricular outflow tract (LVOT), AAo, arch, proximal descending aorta (PDAo), and distal descending aorta (DDAo). In each region peak velocity, kinetic energy (KE), forward flow (FF), reverse flow (RF), and stasis were measured on a voxel-by-voxel basis. T-tests (or non-parametric equivalent) compared flow parameters between cohorts. Univariate and multivariate analyses explored associations between diameter and parametric voxel-by-voxel parameters.</p><p><bold>Results:</bold> Compared to controls, BAV patients showed reduced stasis (<italic>p</italic> &lt; 0.01) and increased RF and FF (<italic>p</italic> &lt; 0.01) throughout the aorta, and KE remained similar. In the AAo, indexed diameter correlated with age (R = 0.326, <italic>p</italic> = 0.01), FF (R = −0.648, <italic>p</italic> &lt; 0.001), RF (R = −0.441, <italic>p</italic> &lt; 0.001), and stasis (R = −0.288, <italic>p</italic> &lt; 0.05). In multivariate analysis, FF showed a significant inverse association with AAo indexed diameter, independent of age. During a median 179 ± 180 days of follow-up, 23 patients (32%) required aortic surgery. Compared to patients not requiring surgery, they showed increased KE and peak velocity in the proximal aorta (<italic>p</italic> &lt; 0.01), accompanied by increased RF and reduced stasis throughout the entire aorta (<italic>p</italic> &lt; 0.01).</p><p><bold>Conclusion:</bold> Novel voxel-by-voxel reverse flow and stasis were altered in BAV patients and are associated with aortic dilation and surgical treatment.</p>