Reference intervals for the echocardiographic measurements of the right heart in children and adolescents: a systematic review
BACKGROUND Left atrial (LA) function is an important modulator of left ventricular filling and has a prognostic role in adult heart failure, but pediatric data are limited. The aim of this study was to characterize the normal LA and right atrial (RA) strain (ε) and strain rate (SR) in infants and children. METHODS Atrial ε and SR were prospectively investigated in 153 subjects using two-dimensional speckle-tracking echocardiography. High-frame rate, three-beat captures of LA (15-segment model; two-chamber, three-chamber, and four-chamber views) and RA (six-segment model; four-chamber view) were analyzed (Vivid 7, EchoPAC BT11). LA and RA segmental and global peak positive ε (εPos) and negative ε (εNeg) and peak positive SR, early negative SR, and late negative SR were measured. Linear and nonlinear regressions of ε and SR were performed with age and heart rate. Relationships of ε and SR with ventricular inflow Doppler and myocardial tissue Doppler indices were explored. RESULTS The age range was 3 days to 20 years, and body surface area range from 0.17 to 2.3 m(2) for the study cohort. Mean global LA εPos, LA εNeg, RA εPos, and RA εNeg were 28 ± 9%, -16 ± 6%, 23 ± 9%, and -15 ± 6%, respectively. Positive correlations were found for global atrial εPos and εNeg with age (P < .001). A marked rate of changes in ε and SR was seen in the first year of life, reaching normal adult values by adolescence. Peak positive SR had a strong negative correlation with age, and early negative SR had a strong positive correlation with age (P < .001), while late negative SR was correlated nonlinearly. Heart rate and age both influenced all LA and RA ε and SR indices. CONCLUSIONS Maturational changes in LA and RA ε and SR occur in normal children and are especially profound in infancy. Consequently, LA and RA performance indices must be interpreted in light of heart rate and age. Normal values and percentiles for atrial ε and SR reported here will provide a foundation for the study of pediatric atrial physiology and function in disease states.