Quantitative Analysis And Outcome Prediction Of Fetal Right Aortic Arch By Echocardiography

Objective:To investigate normal fetuses and fetuses with right aortic arch(RAA)quantitatively in three-vessel and trachea view,the angle and distance between aortic arch and ductal arch were compared,and the different variation in normal and RAA fetuses during growth and risk stratification of fetuses with RAA were explored prenatally.Method:A total of 143 singleton fetuses between 21 and 36 weeks of gestation were enrolled.Five measurements were studied,including the angle and distance between the aortic arch(AO)and ductal arch(DA),the diameters of the AO and DA,and the distance growth rate(DGR).One hundred sixteen fetuses with normal heart structures and function comprised control group and 27 fetuses with RAA and left ductal arch were selected for study group,in which 20 fetuses had two echocardiograms in second and third trimesters respectively.Independent t-tests were performed in comparison of all normally distributed continuous parameters between the study and control groups.They were also applied in analysis of self-control group.The paired t-test was used to compare parameters of fetuses in study group who underwent two examinations in second and third trimesters.Result:The mean AO-DA angle(13.86±2.66°)in study group was significantly lower than that of normal controls(22.01±1.400,P<0.01).A significant increase in mean AO-DA distance was observed in the study group(4.89±1.07 mm)compared to the control group(1.62±0.33 mm,P<0.01).The AO-DA distance increased from the second trimester(1.52±0.35 mm,P<0.01,4.06±0.78 mm,P<0.01)to third trimester(1.71±0.29 mm,P<0.01,5.13±1.10 mm,P<0.01)in the normal and study groups respectively,while no difference was found in AO-DA angle.Fetuses with abnormalities other than RAAs had significantly lower distance growth rates(12.4±5.2%)than those with an isolated RAA(33.7±12.0%).Conclusion:Parameters in our study,especially AO-DA distance and DGR,may be clinically significant.AO-DA distance increased with advancing gestational age in fetuses with or without RAA,and we may speculate that if the AO-DA distance in RAA hardly increases or even decreases in the pregnancy process,pressure symptom and other malformations should be pay attention to.DGR may be restricted when an RAA exists with other malformations.Decreasing DGR in fetuses with RAAs indicate the presence of other malformations.