Estimation of Right Atrial Pressure from the Inspiratory Collapse of the Inferior Vena cava in Pediatric Patients

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 RAP≥ 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.