Limitations of Current Echocardiographic Nomograms for Left Ventricular, Valvular, and Arterial Dimensions in Children: A Critical Review

An echocardiographic quantitative evaluation of the cardiac and vascular structures is often of critical importance for the diagnosis and management of congenital heart diseases. The authors reviewed the accuracy and limits of published echocardiographic nomograms for cardiac chamber, valve, and main vessel dimensions in children, with special attention to the neonatal age group. A computerized literature search in the National Library of Medicine using the keywords “echocardiographic normal/references values ± children/neonates/newborns” was performed. The research was redefined adding separately the keywords “aortic valve/annulus,” “aortic arch,” “atrio-ventricular valve/annulus,” “left ventricle,” “mitral valve/annulus,” “pulmonary valve/annulus,” “pulmonary artery,” and “tricuspid valve/annulus.” The analysis highlights the accuracy of the latest studies but also underscores that some limitations remain. In many studies, the number of healthy subjects was limited, with poor differentiation among age subgroups, and neonates were fully investigated in a very limited number of studies; moreover, data for many cardiac structures were not numerous, especially for the aortic arch and pulmonary branches. Finally, several methodologic limitations were encountered, including the lack of standardization, the different types of body size measurements used for normalization, and the various ways to express normalized data. As a result, nomograms were heterogeneous and although for some cardiac structures provided comparable confidence intervals, for others showed widely different values. The lack of solid, standardized nomograms, based on a large set of healthy children, may affect accuracy in estimating the severity of defects, especially in neonates, and possibly introduce bias in the clinical decision-making process.