A total of 76 consecutive patients with BAV disease (57±10 years, 71% male) underwent aortic valve replacement (AVR) ± proximal aortic surgery from January, 2012 through April, 2013. There was a subgroup of 58 (76%) patients with BAV stenosis (Group I), whereas the remaining 18 (14%) patients had isolated BAV insufficiency (Group II). Preoperative cardiac phase-contrast cine-magnetic resonance imaging (MRI) was performed in order to detect the area of maximal flow-induced stress in the proximal aorta. Based on MRI-data, two aortic wall samples i.e., area of the maximal stress (jet-sample) and the opposite aortic wall (control-sample) were collected during surgery. Aortic wall changes were graded based on 7 histological criteria (i.e., each from 0 to 3+) and were summarized in a sum-score. Histological sum-score (0 to 21+) was calculated and compared between samples (i.e., jet- vs. control-sample).