Prenatal prediction of the postnatal biventricular physiology of fetuses with borderline left ventricle

Background: Predicting the postnatal biventricular physiology of fetuses with borderline left ventricle remains challenging. This study clarified fetal echocardiographic predictors of successful postnatal biventricular physiology establishment. Methods Forty-nine fetuses with a left ventricular (LV) width (LVw) z-score <-2.0, LV length z-score <-2.0, or LVw/right ventricular width (RVw) ratio < 0.8 were retrospectively analyzed. Patients were divided into group B (successful postnatal biventricular physiology; n = 45) and group F (Fontan palliation for LV hypoplasia; n = 4). The z-scores of fetal cardiac structures, left and right cardiac structure ratios, LV diameter (LVd) changes, and flow directions at the foramen ovale (FO) were compared. Results The median gestational ages at fetal echocardiography and at birth were 31 weeks and 38 weeks, respectively. The prenatal LVw/RVw ratio, aortic valve (AoV)/pulmonary artery valve (PAV) ratio, AoV z-score, and change in the LVd were significantly higher and the RVw z-score was significantly lower in group B. Of the 42 patients whose blood flow direction was recorded at the FO, right-to-left shunts were identified in 29 (64%) in group B and in 0 in group F. The LVw/RVw ratio, AoV/PAV ratio, and AoV z-score significantly predicted postnatal biventricular physiology. For patients with bidirectional or left-to-right blood flow, the best predictor was the LVw/RVw ratio (cutoff value, 0.571; sensitivity, 100%; specificity, 100%; area under the curve, 1.0). Conclusions For patients with borderline left ventricle and heterogeneous cardiac defects, the blood flow direction at the FO and LVw/RVw ratio during the third trimester are good predictors of postnatal biventricular physiology outcomes.