Strategies for diagnosis of fetal right atrium dilation: based on fetal cardiac anatomy and hemodynamics

BACKGROUND: Fetal right atrium (RA) dilation is frequently detected in routine screenings while it remains a challenge to clarify the reasons. This study aimed to analyze the cardiac anatomy and hemodynamics of fetal RA dilation and the changes of hemodynamic indexes. METHODS: In the retrospective study, 420 fetuses with RA dilation were included, which were classified into the physiological group (n = 202), volume overload group (n = 142), and the pressure overload group (n = 76). The ratio of right atrium to left atrium (RA/LA) were measured at four-chamber view. Peak velocity of tricuspid regurgitation (V(TR)) was recorded in each case, if existed. RESULTS: The RA/LA ratio in the volume overload group is significantly higher than both the pressure overload group and the physiological group (both P = 0.000) throughout the pregnancy while no difference presents between the pressure overload group and the physiological group (P = 0.694 for 19–31 GW, and P = 0.974 for 32–36 GW, respectively). The V(TR) in the pressure overload group (3.29 ± 0.58 m/s) is significantly higher than both the volume overload group (1.85 ± 0.45 m/s, P = 0.000) and the physiological group (0.88 ± 0.45 m/s, P = 0.000). The volume overload group shows a significantly higher V(TR) than the physiological group (P = 0.000). In the volume overload group, the ductal contraction/closure shows a significantly higher V(TR) than that in the pulmonary valve stenosis/atresia (3.98 ± 0.41 m/s vs. 3.03 ± 0.38 m/s, P = 0.000). CONCLUSIONS: A strategy proposed herein is useful to clarify the reasons for RA dilatation by systematically assessing fetal hemodynamics, which may facilitate the sonographers to make an accurate diagnosis of congenital heart disease.