Two-dimensional echocardiographic aortic root dimensions in normal children and adults

Abstract

Two-dimensional echocardiography is increasingly used to measure aortic root dimensions, which provide prognostic information in aortic regurgitation and the Marfan syndome. Aortic root dilatation is currently detected by nomograms based on M-mode echocardiographic data. Aortic root diameters measured by 2-dimensional echocardiography at the anulus, sinuses of Valsalva, supraaortic ridge and proximal ascending aorta in 135 normal adults and 52 normal children were compared with age, gender, body habitus, blood pressure and stroke volume, and with M-mode findings and normal limits. Two-dimensional measurements at the sinuses of Valsalva were larger than M-mode aortic root values (p < 0.001), and use of 2-dimensional values with M-mode nomograms falsely diagnosed aortic dilatation in 40% of normal children and 19% of normal adults. Two-dimensional measurements at the sinuses closely correlated with body surface area in children (r = 0.93, p < 0.0005), moderately in adults younger than 40 years of age (r = 0.71, p < 0.0005) and weakly in older adults (r = 0.40, p < 0.0005). In adults, gender influenced aortic root size at all levels (p < 0.001), but dimensions were similar when indexed for body surface area. Age strongly influenced supraaortic ridge and ascending aortic diameters; blood pressure and stroke volume had no independent effect on aortic size. In conclusion, (1) 2-dimensional echocardiographic aortic root dimensions are influenced by age and body sue but not by blood pressure; (2) aortic root dilatation is overdiagnosed when aortic diameter at the sinuses of Valsalva is compared with M-mode nomograms; (3) nomograms comparing aortic diameter with body surface area should be used in children; and (4) although use of nomograms based on body size in adults should maximize sensitivity for aortic dilatation, 98% specificity is attained by use of an upper normal limit of 2.1 cm/m 2 for aortic diameter at the sinuses of Valsalva in both men and women.