Quantitative Study Of The Distance Between The Left Atrial Posterior Wall And The Descending Aorta In Four Chamberview Of The Fetal Heart

Objective:The main goal was to quantitatively study the distance between the left atrium posterior wall and the descending aorta (DLD) in the normal fetal four-chamber view using fetal echocardiography and to develop a normal reference range for it.Methods:A retrospective cross-sectional study of 300 singleton normal fetals was performed for standard biometry biparietal diameter (BPD) and femoral diaphysis length (FL) and an assessment of gestation age (GA) (no more than 2 weeks). 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. 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 were found 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= 0.011GA +0.083, Y= 0.048BPD+0.063, Y= 0.054FL+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), or absent pulmonary valve syndrome (APVS) or other complex congenital heart defects.