Objective: Paucity of data exists between mean right atrial pressure (RAP) and inferior vena cava (IVC) size and collapsibility in pediatric patients with congenital heart disease.

Methods: In a prospective study, fifty consecutive pediatric patients with different congenital heart diseases who had right side cardiac catheterization were studied, comparing right atrial pressure with simultaneous M-mode echocardiographic measurement of inferior vena cava diameter. Mean age of the patients was 4.96±4.05 years (30 male and 20 female). Patients were categorized into two groups according to their right atrial pressure (RAP) as measured by cardiac catheterization: Group 1 (40 patients) were those with mean RAP <8 mmHg and group 2 (10 patients) who had a mean RAP³ 8 mmHg.

Findings: In M-mode echocardiography IVC size was statistically different (P=0.004 and 0.009) in inspiration and expiration in the two groups. Mean RAP was estimated to be > 8 mmHg when IVC diameter in inspiration was >3.6 (sensitivity of 100%, specificity of 47.5%, +LR=1.9) or if IVC diameter was >6mm in expiration (sensitivity of 70%, specificity of 87%, +LR=4.67).

Conclusion: This study showed that measurement of IVC size in inspiration and expiration can be used as a reliable method for estimation of mean right atrial pressure.