Right to Left Ventricular Diameter Ratio ≥0.42 is the Warning Flag for Suspecting Atrial Septal Defect in Preschool Children: Age- and Body Surface Area-Related Reference Values Determined by M-Mode Echocardiography

Normal Echocardiographic Reference Values of the Right Ventricular to Left Ventricular Endsystolic Diameter Ratio and the Left Ventricular Endsystolic Eccentricity Index in Healthy Children and in Children With Pulmonary Hypertension

Background

An accurate assessment of the right and left ventricle and their interaction is important in pediatric pulmonary hypertension (PH). Our objective was to provide normal reference values for the right ventricular to left ventricular endsystolic (RV/LVes) ratio and the LV endsystolic eccentricity index (LVes EI) in healthy children and in children with PH.

Methods

We conducted an echocardiographic study in 769 healthy children (median age: 3.36 years; range: 1 day—18 years) and validated abnormal values in 44 children with PH (median age: 2.1 years; range: 0.1 months—17.7 years). We determined the effects of gender, age, body length, body weight, and body surface area (BSA) on RV/LVes ratio and LVes EI values. The RV/LVes ratio and LVes EI were measured from the parasternal short axis view between papillary muscle from the endocardial to endocardial surfaces.

Results

Both, the RV/LVes ratio and the LVes EI were highly age-dependent: (i) neonates RV/LVes ratio [median 0.83 (range 0.53–1.37)], LVes EI [1.21 (0.92–1.45)]; (ii) 12–24 months old: RV/LVes ratio: [0.55 (0.35–0.80)], LVes EI: [1.0 (0.88–1.13)]; iii) 18th year of life RV/LVes ratio: [0.53 (0.32–0.74)], LVes EI: [1.0 (0.97–1.07)]. Healthy neonates had high LVes EI and RV/LVes ratios, both gradually decreased within the first year of life and until BSA values of about 0.5 m2, body weight to about 15 kg and body length to about 75 cm, but were almost constant thereafter. Children (>1 year) and adolescents with PH had significantly higher RV/LVes ratio (no PH: median 0.55, IQR 0.49–0.60; PH: 1.02, 0.87–1.26; p < 0.001) and higher LVes EI values (no PH: 1.00, 0.98–1.00; PH: 1.53, 1.26–1.71; p < 0.001) compared to those without PH. To predict the presence of PH in children > 1 year, we found the following best cutoff values: RV/LVes ratio ≥ 0.67 (sensitivity: 1.00, specificity: 0.95) and LVes EI ≥ 1.06 (sensitivity: 1.00, specificity: 0.97).

Conclusion

We provide normal echocardiographic reference values of the RV/LVes ratio and LVes EI in healthy children, as well as statistically determined cutoffs for the increased values in children with PH.

Growth of Cardiovascular Structures from the Fetus to the Young Adult

The size, hemodynamics, and function of cardiovascular structures change dramatically from the early fetal life to late adolescence. The principal determinants of cardiovascular dimensions are related to the blood flow needed to meet metabolic demands. This demand is in turn tightly related to body size and body composition, keeping in mind that various tissues may have different metabolic rates. There is no simple model that links cardiac dimensions with a single body size measurement. Consequently, despite abundant scientific literature, few studies have proposed pediatric reference values that efficiently and completely account for the effect of body size. Other factors influence cardiovascular size and function in children, including sex. The influence of sex is multifactorial and not fully understood, but differences in body size and body composition play an important role. We will first review the determinants of cardiovascular size and function in children. We then explore the evaluation and normalization of cardiovascular size and function in pediatric cardiology in relation to the growth of cardiovascular structures during childhood, with a particular focus on sex differences.