Structural abnormalities in the non-dilated ascending aortic wall of bicuspid aortic valve patients

Background: A bicuspid aortic valve (BAV) is the most common congenital cardiac malformation. The development of the aortic valve is closely related to the development of the ascending aorta, associated with structural differences in the bicuspid aorta. Here we describe the non-dilated ascending aortic wall in bicuspid aortic valve patients.Methods: BAV (n = 41) and tricuspid aortic valve (TAV) (n = 18) non-dilated ascending aortic wall samples were studied. We investigated the following features of the aortic wall: vessel wall thickness, endothelial cell morphology, atherosclerosis, and elastic lamellae organization. Medial pathologic features encompass-ing elastic fiber thinning, fragmentation and degeneration, overall medial degeneration, mucoid extracel-lular matrix accumulation, and smooth muscle cell nuclei loss were studied. Furthermore, we included apoptosis, periaortic inflammation, and the level of expression of differentiated vascular smooth muscle cells.Results: The non-dilated BAV ascending aortic wall is characterized by a significantly thinner intimal layer, without features of atherosclerosis ( P < .001). The medial layer is significantly thicker ( P < .001) with more mucoid extracellular matrix accumulation ( P < .001). All other medial pathologic features were more prominent in the TAV ( P < .001). The media has significantly less differentiated vascular smooth muscle cells ( P < .001) between the neatly regulated elastic lamellae which are thinner in the BAV as compared to the TAV ( P < .0 0 01).Conclusions: The BAV ascending aorta without dilatation is characterized by a differentiation def ect of vascular smooth muscle cells in the media and a significantly thinner intimal layer without overt patho-logic features.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

Non-dilated ascending aortic wall in patients with bicuspid aortic valve is characterized by a thinner intimal layer, thicker medial layer with more mucoid extracellular matrix accumulation, and less differentiated vascular smooth muscle cells compared to patients with tricuspid aortic valve. Other medial pathologic features are more prominent in patients with tricuspid aortic valve.