Characterization of the Relationship between Bicuspid Aortic Valve Morphology and Hemodynamics
Mangiameli, Daniel J
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Bicuspid aortic valve (BAV) is the most common congenital heart defect and may lead to secondary aortopathy such as aortic valve stenosis and regurgitation, potentially causing noticeable symptoms such as shortness of breath, chest pain, and dizziness. Although previously overshadowed by the genetic theory, there has recently been a belief that hemodynamics may play a larger role in the cause of secondary aortopathy in BAV than previously thought. However, hemodynamic studies have been impeded by lengthy data analysis protocols limiting their effectiveness and reproducibility. This work applied and further refined a novel semi-automated technique developed during a pilot study to process and analyze MRI data of the aorta and aortic valve based on 2D bSSFP cine and 4D flow MRI. The results were then used to characterize the morphology and hemodynamics between BAV fusion patterns. The protocol was applied to 24 size-matched TAV controls (n =24, mid ascending aorta (MAA) diameter =38.0±4.9 mm) and 28 BAV patients with aortic dilatation (n =14 RL- BAV, MAA diameter =38.1±5.3 mm; n =14 RN-BAV, 36.5±6.6 mm). RN-BAV subjects displayed a stronger correlation between hemodynamic metrics in the proximal AAo with diameter in the distal AAo when compared to size-matched TAV controls and RL-BAV subjects. The distal AAo diameter was found to be strongly correlated to the flow displacement (R2adjusted =0.75) and flow angle (R2adjusted =0.66) at the proximal AAo. Orifice circularity was also strongly correlated (R2adjusted =0.53) to the distal AAo diameter in RN-BAV subjects. This study not only demonstrated the feasibility of a less user dependent protocol, but also highlighted several key metrics that are significantly different between fusion patterns of RN-BAV and RL-BAV patients.