• Matthew A Thompson, Benjamin Kramer, Samar A Tarraf, Emily Vianna, Callan Gillespie, Emidio Germano, Brett Gentle, Frank Cikach, Ashley M Lowry, Amol Pande, Eugene Blackstone, Jennifer Hargrave, Robb Colbrunn, Chiara Bellini, and Eric E Roselli.
• Department of Thoracic and Cardiovascular Surgery, Aortic Center, Heart, Vascular & Thoracic Institute, Cleveland Clinic, Cleveland, Ohio.
• J. Thorac. Cardiovasc. Surg. 2023 Dec 26.

ObjectivesBicuspid aortic valve (BAV) aortopathy is defined by 3 phenotypes-root, ascending, and diffuse-based on region of maximal aortic dilation. We sought to determine the association between aortic mechanical behavior and aortopathy phenotype versus other clinical variables.MethodsFrom August 1, 2016, to March 1, 2023, 375 aortic specimens were collected from 105 patients undergoing elective ascending aortic aneurysm repair for BAV aortopathy. Planar biaxial data (191 specimens) informed constitutive descriptors of the arterial wall that were combined with in vivo geometry and hemodynamics to predict stiffness, stress, and energy density under physiologic loads. Uniaxial testing (184 specimens) evaluated failure stretch and failure Cauchy stress. Boosting regression was implemented to model the association between clinical variables and mechanical metrics.ResultsThere were no significant differences in mechanical metrics between the root phenotype (N = 33, 31%) and ascending/diffuse phenotypes (N = 72, 69%). Biaxial testing demonstrated older age was associated with increased circumferential stiffness, decreased stress, and decreased energy density. On uniaxial testing, longitudinally versus circumferentially oriented specimens failed at significantly lower Cauchy stress (50th [15th, 85th percentiles]: 1.0 [0.7, 1.6] MPa vs 1.9 [1.3, 3.1] MPa; P < .001). Age was associated with decreased failure stretch and stress. Elongated ascending aortas were also associated with decreased failure stress.ConclusionsAortic mechanical function under physiologic and failure conditions in BAV aortopathy is robustly associated with age and poorly associated with aortopathy phenotype. Data suggesting that the root phenotype of BAV aortopathy portends worse outcomes are unlikely to be related to aberrant, phenotype-specific tissue mechanics.Copyright © 2023 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

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