Echocardiographic anatomy of ascending aorta dilatation: correlations with aortic valve morphology and function

Different anatomical forms of proximal aortic dilations associated with aortic valve disease can be distinguished by echocardiography. Differences in the anatomy could reflect different pathogeneses and need for different therapeutic approaches. The present study assessed the clinical features associated to each anatomical form, particularly focusing on the relations with valve morphology and function.

Trans-thoracic and trans-esophageal echocardiography reports of 552 adult patients (mean age 60.4+/-12.8 years; 379 male) with mild to severe proximal aorta dilation were reviewed. The relationships between the anatomy of aorta dilatation (distinguished into "root type" dilatation, with maximal enlargement at the sinuses, and "mid-ascending type", with maximal diameter at the mid-ascending tract) and aortic valve morphology (tricuspid/bicuspid) and function (normal/stenosis/regurgitation) were assessed. The relations with other clinico-echocardiographic variables were also tested in univariate and multivariate analysis.

A "root type" dilatation was found in 4.9% tricuspid patients with stenosis, 32.3% with regurgitation, 22.5% with normal valve function (p=0.018). Dilatation prevailed at the mid-ascending tract in patients with bicuspid aortic valve, irrespective of valve function (stenotic: 92.9%, regurgitant: 87.9%, normal: 94.3%; p=0.23). Predominant root involvement was significantly more prevalent in male patients (24.8% versus 5.2% in females; p<0.001). In multivariate analysis, predominant aortic valve regurgitation (OR=1.83; p=0.028) independently predicted root site, while predominant aortic valve stenosis (OR=3.70; p=0.001), bicuspidity (OR=2.90; p=0.005) and female sex (OR=6.10; p<0.001) predicted mid-ascending site.

Pathogenetical considerations arise from the evidence of preferential mid-ascending localization of bicuspid-associated aortic dilatations. This finding is consistent with previous studies on bicuspid valve models revealing a wall stress overload beyond the sino-tubular ridge.