Normal aortic dimensions and flow in 168 children and young adults

Knowledge of normal aortic dimensions is important while evaluating children with aortic root dilatation.

The purpose of the study was to create normal values for aortic dimensions with two-dimensional echocardiography and for aortic flow velocities with Doppler echocardiography in healthy children and young adults.

One hundred and sixty-eight healthy children were studied by a single observer using digitized two-dimensional (2DE) and Doppler echocardiography.

The 2DE measurements were obtained at the level of aortic annulus, sinus, sinotubular junction, before the origin of innominate artery, before and after the origin of left carotid artery, after left subclavian artery and descending aorta at the level of the diaphragm. Doppler measurements were made from ascending aorta and from descending aorta.

For the analysis the subjects were divided into five groups according to body surface area (BSA): 0.5-0.75 m2, 0.75-1.0 m2, 1.0-1.25 m2, 1.25-1.5 m2 and over 1.5 m2. Aortic dimensions normalized to BSA were greater in smaller children at all levels. All diameters correlated closely with age, BSA, height and weight (for each r>0.75, P<0.001). The best predictor of aortic dimensions was BSA with r values over 0.84 for all estimates (P<0.001). The diameters of ascending and descending aorta were similar in both genders when indexed to BSA. Flow velocities in descending aorta were greater than those measured in ascending aorta (P<0.001 for all measurements). There were significant inverse correlations with heart rate and velocity time integral in ascending and descending aorta (r=-0.32 and -0.53, P<0.001, respectively).

The presented aortic dimensions at eight levels from the valve annulus to the descending thoracic aorta by 2DE in conjunction with Doppler measurements of ascending and descending aorta in 168 healthy subjects will serve as reference data for further studies and clinical use in patients with various cardiac abnormalities.