Quantification of Z-scores of normal fetal left and right ventricular diameters using early fetal echocardiography / 中华超声影像学杂志

ABSTRACT

Objective:To investigate the association of left and right ventricular diameters in normal early pregnancy and early middle pregnancy to the biological growth parameters of fetus, and to establish the reference and Z-score model for left and right ventricles.Methods:Two hundred and forty-six fetuses in normal early pregnancy (11-13 + 6 weeks) and early middle pregnancy (14-17 + 6 weeks) from February 2019 to May 2019 in Sir Run Run Shaw Hospital were examined by routine ultrasound. Non-cardiac fetal biometric parameters included crown-rump length (CRL), biparietal diameter (BPD) and femoral length (FL) and gestation age (GA) based on menstrual age were assessed. The left and right ventricular widths (LVW, RVW) and ventricular lengths (LVL, RVL) were measured at the end of diastolic period by obtaining the standard four chamber view of fetal echocardiography. The end-diastolic areas (LVA, RVA) as the products of the ventricular widths and lengths, the global spherical indexes (GSI) of left and right ventricles (LVSI, RVSI), the ratios of left and right ventricular widths (LVW/RVW), the length ratios (LVL/RVL) and the area ratios (LVA/RVA) of both ventricles were calculated.GA, BPD and FL were used as independent variables. The predicted cardiac parameters and its derivative parameters were used as dependent variables. The corresponding reference range was established. The correlation between each standard deviation (SD) and independent variables was analyzed, and the corresponding Z-scores of left and right ventricular diameters were calculated by using the formula. Results:①LVW, RVW, LVL, RVL were found positively correlated with the increase of GA, BPD and FL, and the correlation between GA and LVW, RVW was the highest ( r=0.928, 0.930; all P<0.000 1). ②There was a positive correlation between LVA, RVA and GA ( r=0.868, 0.872; all P<0.000 1). LVSI, RVSI were found negatively correlated with GA ( r=-0.844, -0.861; all P<0.000 1), and LVSI>RVSI. LVW/RVW<1 and almost close to 1, the ratios decreased with the increase of GA( r=0.147, P<0.000 1). LVL/RVL>1, the ratios increased with the increase of GA( r=0.313, P<0.000 1). LVA/RVA>1, but there was no correlation with GA. ③The SD values of LVW, RVW, LVL, RVL positively correlated with independent variables. Taking GA and LVW as an example, the linear regression equation of LVW was Y=-5.338+ 0.549GA ( r=0.928, P<0.000 1), and the linear regression equation of LVW-SD was Y=-0.322+ 0.037GA( r=0.131, P<0.000 1). The Z-scores of LVW, RVW, LVL, RVL, LVA, RVA did not change with the changes of GA, BPD, and FL. Conclusions:The normal reference range and Z-scores of left and right ventricular lengths and widths can be simply and reliably established using statistical analysis, and these parameters might have potentials for more accurately and more early evaluating the normal development of fetal heart.