Quantitative study of atrial diameter and Z-score of normal fetuses in middle and late trimester by echocardiography / 中华超声影像学杂志

ABSTRACT

Objective:To analyze the correlation between left and right atrial diameters and fetal biological growth parameters of normal fetuses in middle and late trimester, and to establish normal reference and Z-score model for left and right atria.Methods:Three hundred and ninety-two fetuses in middle and late trimester were prospectively selected from July 2022 to October 2022 in Sir Run Run Shaw Hospital.Non-cardiac biometric parameters included biparietal diameter (BPD), femoral length (FL), and gestational age (GA) based on menstrual age were assessed.Left and right atrial widths (LAW, RAW) and atrial lengths (LAL, RAL) at end-systole, left and right atrial areas (LAA, RAA) at end-systole and the heart area (HA) at end-diastole were measured in standard apical four-chamber or basal four-chamber view. The ratio of RA and LA transverse diameters (RAW/LAW), the ratio of RA and LA length diameters (RAL/LAL), ratio of RA and LA area (RAA/LAA), spherical index of the ratio of RA and LA length to transverse diameter (RASI, LASI), ratio of LA and RA area to heart area (LAA/HA, RAA/HA) were calculated. The best regression equation was established using GA, BPD and FL as independent variables and LAL, LAW, LAA, RAL, RAW, RAA as dependent variable. The correlation between the standard deviation (SD) and the independent variables GA, BPD and FL was analyzed, and then the above statistics were used to calculate the corresponding Z-score for each variable of RA and LA using the regression equation.Results:①Significant positive correlations were found between LAW, RAW, LAL, RAL, LAA and RAA with the increase of GA, BPD and FL, and the highest degree of correlation between RAA, LAA and GA was denoted ( r=0.927, 0.920, all P<0.001). ②Taking GA as an example, there was no significant correlation between RAL/LAL, RAW/LAW and GA ( r=-0.064, 0.077; all P>0.05). RAA/LAA showed a very weak positive correlation with GA ( r=0.106, P=0.037), with normal reference values of 1.002±0.091, 1.091±0.093, 1.059±0.090, respectively. Interestingly RAL/LAL was found close to 1, while RAW/LAW and RAA/LAA were always >1. No significant correlations were found between LAA/HA, RAA/HA and GA ( r=0.003, 0.056; all P>0.05), with normal reference values of 0.155±0.026, 0.163±0.026, respectively, and RAA/HA was found larger than LAA/HA. LASI showed a very weak positive correlation with GA ( r=0.112, P=0.027), while there was no significant correlation between RASI and GA ( r=0.003, P>0.05), the normal reference values were 1.068±0.113, 0.980±0.105, respectively. ③The SD of LAL, LAW, etc.showed a simple linear relationship with the independent variables. Taking RAA and GA as examples, the linear regression equation for RAA was Y=-1.690+ 0.107 0GA ( r=0.927, P<0.001) and the linear regression equation for RAA-SD was Y=-0.107+ 0.010 4GA ( r=0.320, P<0.001). The Z-scores for LAL, LAW, LAA, RAL, RAW and RAA were relatively constant with the growth of GA, BPD and FL, with the corresponding Z-scores for GA were -1.817~3.631( r=0.000 3), -1.605~2.995( r<-0.000 1), -1.700~3.107( r<0.000 1), -1.617~3.466( r=0.000 1), -1.491~3.025( r<-0.000 1), -1.566~3.104( r=0.000 2), respectively. Conclusions:This study preliminarily establish the reference value ranges and Z-score of atrial diameters in normal fetuses during middle and late trimester, providing a reference basis for accurate quantitative evaluation of fetal atrial development and analysis of fetal congenital heart abnormalities, and contributing to the early detection of pathological conditions leading to abnormal atrial size.