Bicuspid aortic valve (BAV) affects ∼2% of the general population and is associated with thoracic aortic aneurysm (TAA) formation. Although there is a genetic component underlying TAA susceptibility, local mechanical environment also plays an important role and this presents a critical gap in our understanding of BAV disease. We sought to investigate the relative contribution of these parameters in BAV patients, applying integrated computational and histological analyses.Methods
Mechanical stress was analysed in patients with BAV planned to undergo surgery using patient-specific imaging data and computational modelling. During surgery, aortic tissue biopsies were collected from discrete areas and the degree of medial wall degeneration was correlated to mechanical stress.Results
Seven male patients (30y, 2-68) with a BAV were studied. Informed consent form was obtained as per institutional guidelines. Phenotypes of aortic dilatation included: mild dilatation of the ascending aorta (n=2), PWS 35KPa (2-79), aneurysm of the ascending aorta extending to the aortic arch (n=3), PWS 59KPa (2-450), and isolated aneurysm of the aortic root (n=2), PWS 56KPa (2-130). The histological analyses displayed marked disruption of the aortic media architecture in areas of elevated mechanical stress (Figure). However, there was no significant association between the degree of medial wall degeneration and corresponding mechanical stress, which may reflect the presence of inherent wall abnormalities.Conclusions
The aneurysmal segments of the aorta were uniformly subjected to higher mechanical stress. Medial wall degeneration was more severe in areas of elevated stress. Mechanical stress may exacerbate structural abnormalities of the aortic wall in BAV disease, which are intrinsic in nature.