Background: A geometrical and functional asymmetry in the normal aortic root has been recently demonstrated. Whether the distribution of medial degeneration (MD) within the wall of the dilated ascending aorta in adult patients reflects such asymmetry, still has to be assessed.
Methods: Nineteen patients with fibrocalcific aortic valve disease and dilatation of the intrapericardial aorta, without clinical signs and familiar history of primary elastic connective tissue disorders, underwent surgery. Biopsies (57 specimens) were taken in each patient from three areas of the ascending aortic wall distal to the three sinuses of Valsalva. MD lesions found at histology in each specimen were classified in three degrees. Comparisons were made between the three sites as to distribution of the three degrees and between one site and the other two as to incidence of the highest degree.
Results: A mild degree of MD was found in 26 specimens (45.6%), moderate in 14 (24.6%), severe in 17 (29.8%). The distribution of the three degrees of MD changes was significantly different between one of the three studied wall areas and the other two (P<0.001): a significantly greater incidence of the highest degree of involvement in the aortic wall distal to the non-coronary sinus than in the wall areas corresponding to the coronary sinuses was found (P<0.001).
Conclusions: MD lesions in dilated intrapericardial aorta are more severe in the wall area distal to the non-coronary sinus, likely due to haemodynamic stress asymmetry.