Relation of aortic wall alterations and ascending aorta diameter in patients with bicuspid aortic valve

Patients with a bicuspid aortic valve tend to develop local enlargement in the convexity of the ascending aorta. There is controversial discussion as to whether this is a dilatation caused by abnormal hemodynamic stress or an aneurysm due to a common developmental defect of the aortic valve and the aortic media. Systematic studies of aortic wall specimens from patients with different diameters of the ascending aorta have not been available until now. We investigated histologically (HE, E.v.G., alpha-Actin, Alcian blue/van Gieson) aortic wall tissue obtained from 107 patients (31 female, 76 male, mean age 60.9+/-12.8 years) with a bicuspid aortic valve. According to the preoperative measurement of the ascending aorta diameter, which was done by CT scan, angiography or echocardiography, the patients were divided into three groups [Group 1: ascending aorta diameter <3.8 cm; Group 2: diameter >/=3.8-4.9 cm and Group 3: diameter >/=5.0 cm]. We looked for histological signs of dilatation or more severe structural changes. All patients of group 1 showed normal findings in histological examination. In 23 of 43 patients in group 2 (65.1%), we found histological signs of dilatation. Histological signs of dilatation were present in all patients in group 3. We conclude that in patients with a bicuspid aortic valve histological signs of dilatation were more frequently found with increasing diameter of the ascending aorta. More severe histological changes, such as cystic media necrosis, were not present.