Abstract Body (Do not enter title and authors here):
Background: Fragility of the ascending aortic wall has been reported in patients with aortic regurgitation (AR), thought to be affected by turbulence in the ascending aorta. However, the mechanism behind this effect is unclear. We hypothesized that turbulence in the ascending aorta of AR patients causes changes in the polarization of endothelial cells. This study aimed to clarify that the polarization of endothelial cells in the ascending aortic wall is altered in AR patients.
Methods: Twenty patients who underwent ascending aortic replacement at our institution from October 2022 to July 2023 were included: ten with thoracic aortic aneurysms (TAA) and ten with TAA and AR. The polarization of endothelial cells in the greater curvature of the ascending aortic wall collected during surgery was evaluated by measuring the ratio of the long axis to the short axis, the angle between the long axis and the blood flow axis, and the alignment of the Golgi apparatus and nucleus parallel to the blood flow.
Results: There were no significant differences in patient background between the AR and non-AR groups. Additionally, there was no significant difference in the diameter of the ascending aorta between the two groups (AR vs. non-AR, 47.7±3.8 mm vs. 44.5±2.2 mm, p=0.479). The long axis to short axis ratio (aspect ratio) of endothelial cells in the ascending aorta was significantly smaller in the AR group than in the non-AR group. The angle (θ) between the long axis of the endothelial cells and the blood flow axis was significantly smaller in the AR group than in the non-AR group. The ratio of Golgi apparatus and nucleus alignment parallel to the blood flow was significantly lower in the AR group than in the non-AR group. Degeneration of the aortic tunica media was also observed in the AR group compared to the non-AR group.
Conclusion: The results of this study suggest that the presence of AR alters the polarization of endothelial cells in the ascending aortic wall.