There is a genetic cause of bicuspid aortic valve. Dilatation of the aortic root and ascending aorta has long been considered genetically determined too and treated accordingly. In recent years, basic research combined with advanced cardiac imaging has made a strong case for another cause of this dilatation: an altered flow profile in the ascending aorta due to the abnormal geometry of the bicuspid valve, leading to an area of altered wall shear stress, which in turn leads to remodelling of the aortic wall, with apoptosis of vascular smooth muscle cells and disruption of media layer as a result. These histological changes, previously referred to as cystic medial necrosis, form the basis of a loss of structural integrity of the aortic wall, which makes it prone to dilatation, dissection, and rupture.
Spontaneous rupture of abdominal aorta — an unusual manifestation of an idiopathic cystic medial necrosis (Gsell-Erdheim syndrome) and literature overview
