Reference Values and Calculation of Z-Scores of Echocardiographic Measurements of the Normal Pediatric Right Atrium and Right Atrial Enlargement in Children with Atrial Septal Defect or Pulmonary Hypertension

Background: Determination of right atrial (RA) size has recently gained more interest, especially in patients with congenital heart disease (CHD) with right heart dysfunction. We investigated growth related changes of RA dimensions in healthy children and the predictive value of RA variables in identifying enlarged RAs in children with secundum atrial septal defect (ASD) and children with pulmonary hypertension (PH) secondary to CHD (PH-CHD).

Methods: We conducted a prospective study in 516 healthy children (age range: 1 day to 18.9 years), in 80 children with a moderate-sized to large ASD (> 7 mm superior-inferior dimension; age range: 2 days to 18.1 years), and in 42 children with PH-CHD (age range: 2 days to 18.2 years). We determined the effects of age, body weight (BW), body length (BL), and body surface area (BSA) on three RA variables, i.e.: end-systolic major-axis length, end-systolic minor-axis length, and end-systolic area. RA end-systolic length and area z-scores, derived from the healthy population, increased with age, BW, BL, and BSA in ASD (r 0.30–0.55) and PH (r 0.35 to 0.50) patients. RA dimensions above the upper normal reference range (z-score of > +2) indicated the existence of an ASD or PH-CHD, with a sensitivity of 64% and 78%, and a specificity of 96 to 98%.

Conclusion: We provide normal values (z-scores -2 to +2) for RA length, and area. Enlarged RA variables with scores > +2 were important predictors in identifying enlarged RÁs in children with ASD and/or PH-CHD.