**3. Dystrophic aortic roots**

#### **3.1 Dystrophic aortic roots: A diameter disease**

Dystrophic aortic roots are characterized by dilation of both functional diameters of the aortic root: the aortic annular base and sino-tubular junction (STJ) diameters (>25mm and >35 mm respectively), preventing coaptation of otherwise thin and pliable valves (De Waroux et al., 2007; La Canna et al., 2009; Lansac et al., 2008, 2010c). Cusp prolapse is often associated with root aneurysms and is the most common cause of isolated dystrophic aortic insufficiency (AI). On an echocardiographic study of patients with aortic root aneurysms (n=700) or isolated aortic insufficiency (n=595), average aortic annular base diameter was respectively 26.4mm (25-27.5mm) and 27.3mm (27-28mm), and average sinotubular junction was respectively 45.3mm (39.5-52.4mm) and 31mm (28-35mm). Ratio between the sinotubular junction and aortic annular base diameters was 1.7 in case of root aneurysms, whereas for isolated aortic insufficiency it was 1.1 (Lansac et al., 2008, 2010c).
