Persistent left superior vena cava causing change in cardiac chamber size: anatomical and hemodynamic changes

Background: Persistent left superior vena cava (PLSVC) is one of the most common abnormalities of the fetus during pregnancy. The aim of this study was to assess the utility of two-dimensional (2D) ultrasonography in evaluating fetal cardiac chamber sizes and major artery diameters for comparing isolated PLSVC with normal fetuses.

Methods: We retrospectively analyzed 166 cases of isolated PLSVC and 166 normal fetuses, measuring heart chamber and major artery diameters. The thoracic transverse diameter (TTD), ventricle sinistrum (VS), ventriculus dexter (VD), atrium sinistrum (AS), and atrium dextrum (AD) were measured in the four-chamber view. The aortic diameter (AOD), pulmonary artery diameter (PAD), aortic velocity (AOV), and pulmonary artery velocity (PAV) were measured in the left and right ventricular outflow tract sections, respectively. The arterial duct diameter (ADD) was measured in the three-vessel-trachea (3VT) view.

Results: Compared with normal fetuses, isolated PLSVC cases showed significant differences in VD, AD, AOD, PAD, ADD, AOV, and PAV (P<0.05). The ratios of cardiac chamber and major artery diameters, including VD/VS and AD/AS also differed significantly between the two groups (P<0.05). Fetal VD positively correlated with AD (R²=0.96, P<0.001) and PAD correlated positively with AOD (R²=0.54, P<0.001) in the isolated PLSVC group. AD achieved an area under the curve (AUC) of 0.674 with 47.59% sensitivity and 83.03% specificity, whereas AOD yielded an AUC of 0.695 with 50.00% sensitivity and 83.13% specificity. Combined use of AD and AOD enhanced diagnostic accuracy, demonstrating a positive predictive value of 81.2% and a negative predictive value of 75.6%.

Conclusions: Fetal isolated PLSVC was associated with changes in cardiac chamber size, which may be important for prenatal diagnosis due to hemodynamic changes caused by coronary sinus dilation.