Quantification of the distance of pulmonary valve to pulmonary artery bifurecation of normal fetuses in second and late trimester

Abstract

Objective To quantitatively study the correlation of the distance of pulmonary valve to pulmonary artery bifurcation (DPVB) of normal fetuses in second and late trimester with the fetal biometric parameters using fetal echocardiography. Methods The distances of pulmonary valve to pulmonary artery bifurcation in end-systole (DPVBs) and in end-diastole (DPVBd) were measured in a standard short axis view or right ventricular outflow tract view using fetal echocardiography on 419 normal fetuses. The gestation ages ranged from 20 to 35+ weeks. Fetal non-cardiac biometric parameters including biparietal diameter (BPD), femoral length (FL) and gestation age (GA) based on menstrual age, pulmonary valve annulus diameters (PA) at end-systole were measured. The correlation between DPVBs, DPVBd and non-cardiac biometric parameters were analyzed. Results In normal fetuses, the DPVBs was (1.14±0.24)cm with a range of 0.67 to 1.61 cm, the DPVBd was (0.93±0.20)cm with a range of 0.53 to 1.33 cm. The DPVBs and DPVBd were increased with the growth of GA, and were positively correlated with GA, BPD, FL and PA (r=0.827, 0.798, 0.793, 0.769; 0.802, 0.764, 0.773 and 0.771, respectively, all P<0.001). The linear regression equations between DPVBs, DPVBd and GA, BPD, FL, PA were: Y=0.054×GA-0.369, Y=0.184×BPD-0.179, Y=0.217×FL+ 0.011, Y=1.602×PA+ 0.156, Y=0.045×GA-0.330, Y=0.152×BPD-0.157, Y=0.182×FL-0.018, Y=1.380×PA+ 0.080. Conclusions In normal fetuses, the DPVBs and DPVBd increase with the growth of GA, and have good correlation with GA, BPD, FL and PA, respectively. Normal reference ranges of DPVBs and DPVBd have been provided. These normative data may become a new tool for assessment of fetal heart, especially has potential applications in screening of complex congenital heart defects. Key words: Echocardiography; Fetus; Developmental biology; Distance of pulmonary valve to pulmconary artery bifurcation