Quantitative Assessment Of Left Atrial Volume In Normal Human Fetuses Using Left Atrial Volume Tracking Method

ObjectivesUsing left atrial volume tracking method (LAVT), time-left atrial(LA) volume curves(TLAVCs) can be automatically obtained. The goal of this study was to examine whether this method can be used to evaluate LA volumes and provide reference values for LA volumes in normal human fetuses.Materials And MethodsTwo hundred and four normal human fetuses (21 to 40 weeks) were enrolled in this study to establish normal values for human LA volumes during the second and third trimester of gestations. Using LAVT, the maximal and minimal LA volumes (LAVmax and LAVmin) were measured from TLAVCs. Calculations were made in 4 to 6 consecutive cardiac cycles and averaged. LA empting fraction (EF)was calculated as the difference between LAVmax and LAVmin,divided by LAVmax. The maximal and minimal LA area (LAAmax and LAAmin) were measured from the 4-chamber view using manual tracing method. Calculations were made in 3 consecutive cardiac cycles and averaged. The results were correlated with gestational weeks to establish reference values. Curve estimation and Pearson correlation analysis was used to examine the relation between gestational age and Vmax and Vmin. Amax and Amin was plotted against gestational age using linear regression analysis. Based on the equations acquired for both the mean and the SD, population reference intervals for gestational age were estimated. Bland-Altman analysis was used to compare the measurement agreement and bias for a single observer and two observers. P<0.05 was considered statistically significant.ResultsMean LAVmax increased from 0.27 ml at 21 weeks to 4.15 ml at 40 weeks, and mean LAVmin increased from 0.13ml at 21 weeks to 2.26ml at 40 weeks. Mean LAAmax increased from 0.61cm2 at 21 weeks to 2.64 cm2 at 40 weeks, and mean LAAmin increased from 0.34 cm2 at 21 weeks to 1.53 cm2 at 40 weeks. Multiple regression analysis was used to examine the relation between gestational age and LAVmax and LAVmin. The curves of best fit for mean left atrial Vmax and Vmin against gestational age as the independent variable were quadratic regression equations. Linear regression equations provided the best fit for the relationships of mean LAVmax and LAVmin with mean LAAmax and LAAmin, respectively. Bland-Altman analysis showed that there was good intra- and interobserver agreement of the LAVmax measurements.ConclusionThis study establishes reference values for fetal left atrial volumes during the second half of gestation. The growth curve of LA volume of normal human fetus is in line with that of left ventricular. It indicates that the LAVT is a feasible and repeatable method to estimate fetal LA volumes during the second half of gestation.