We read with interest the article by den Dekker et al . titled “Comparability of Z -Score Equations of Cardiac Structures in Hypoplastic Left Heart Complex,” which was recently published in JASE and highlights previous observations pertaining to the limitations of current pediatric nomograms.

Despite recent advances, current nomograms still present several numerical and interpretative dilemmas. Indeed, different published nomograms may generate considerably discordant Z scores for a given measurement, thus creating confusion in grading the severity of a given defect.

Newborns with underdeveloped left ventricles illustrate how these discrepancies in children with congenital heart disease (CHD) may result in surgical and outcomes data that cannot be compared.

We believe, however, that some clarifications are needed. Although den Dekker et al . emphasized the limitations of current pediatric nomograms, this issue has been discussed by a number of authors over the past 2 years. The lack of standardization in pediatric echocardiography is an important problem that includes not only the paucity of solid pediatric nomograms but also the lack of a standardized approach to classifying the severity of some common forms of CHD. In particular, there is an absence of clear recommendations for (1) defining and classifying the severity of valvular heart disease in children, (2) grading the severity of defects characterized by left-to-right shunting, and (c) differentiating between some conditions that are often benign and others that are often pathologic (such as patent foramen ovale vs true atrial septal defect). The lack of a standardized system to classify the severity of CHD, and the absence of guidelines and recommendations for their management, may result in discordant decisions for managing children with the same defect, which at times may be extremely relevant.

Unfortunately, what occurs for children with underdeveloped left ventricles is not an isolated case but instead is the tip of the iceberg. In fact, discrepancies in the evaluation of echocardiographic data may result in opposite strategies and outcomes in a number of types of CHD, including not only complex disorders but also benign lesions such as hemodynamically insignificant left-to-right shunts such as small septal defects or silent patent ductus arteriosus, for which decisions regarding hospital discharge, follow-up, and even treatment may depend on the clinician’s opinion or local practice patterns. For instance, in the United States, some centers advocate immediate discharge of children with silent patent ductus arteriosus, whereas others recommend routinely closing the duct to prevent infective endocarditis.

Regarding the need for new and more reliable nomograms, awareness of the problem has led to efforts to address some of the present drawbacks. Approaches to overcoming some of the numerical and methodologic limitations inherent in current nomograms have been proposed, and new studies to establish more robust and accurate pediatric nomograms are ongoing. Nevertheless, we would emphasize the intrinsic difficulty in eliminating some source of error related to physiologic variations during the first hours and days of life. Such variations may strongly affect echocardiographic evaluation in both physiologic and pathologic conditions (such as in the case of hypoplastic left heart complex). Thus, echocardiographic data in newborns with complex CHD should never be considered in isolation (or used as absolute cutoffs for clinical decision making) but rather considered within the clinical context.

In conclusion, we think it is time to issue a loud call regarding the need for standardization in pediatric echocardiography. This will require an extended, and perhaps difficult, step-by-step process that includes the development of more robust nomograms, as well as recommendations based on expert consensus, to classify and grade the severity of the most important congenital and acquired disorders seen in neonates, children, and adolescents in a manner that is widely supported and accepted.