RESUMO
Objective To quantitatively study the distance between the left atrial posterior wall and the descending aorta(DLD)in the normal fetal four-chamber view using fetal echocardiography.Methods The distances between the left atrial posterior wall and the descending aorta in end-systole (DLDs) and in end-diastole(DLDd) were measured in a standard apical four-chamber view using fetal echocardiography in 300 normal fetuses.The gestation ages ranged from 20 to 40 weeks.Fetal non-cardiac biometric parameters included femoral length(FL),biparietal diameter(BPD) and gestation age (GA) based on menstrual age. The correlation between DLDs,DLDd and non-cardiac biometric parameters were analyzed.Results In normal fetuses,the DLDs was (0.32±0.08)cm with a range of 0.19 -0.48 cm,the DLDd was (0.43 ± 0.10)cm with a range of 0.25-0.62 cm.The DLDs and DLDd increased with the growth of GA,and were correlated with GA and BPD and FL significantly (r = 0.545,0.556,0.574,0.530,0.563 and 0.576, respectively,all P <0.001).The linear regression equations between DLDs,DLDd and GA,BPD,FL were:Y =0.009GA+0.041 ,Y =0.038BPD+0.028,Y =0.044 FL+0.073,Y =0.01 1 GA+0.083,Y =0.048 BPD+0.063,Y = 0.054 FL + 0.124,respectively.Conclusions In normal fetuses,the DLDs and DLDd increase with the growth of GA,and have good correlation with GA,BPD,and FL respectively.Normal reference ranges of DLDs and DLDd have been provided.These normative data may be a new tool for assessment of fetal heart,especially has potential applications in screening of total anomalous pulmonary venous connection(TPVAC),absent pulmonary valve syndrome(APVS)or other complex congenital heart defects.