Explore the vast range of titles available.

Background: Borderline left ventricle represents a heterogeneous spectrum of congenital heart disease for which accurate prediction of suitability for biventricular versus univentricular circulation is often difficult. Serial fetal echocardiography may provide dynamic information to support postnatal decision-making. Case Presentation: We report the case of a fetus diagnosed at 32 weeks’ gestation with a borderline left ventricle, ventricular disproportion, hypoplastic left-sided structures, ductal-dependent systemic circulation, and a non-restrictive ostium secundum atrial septal defect. Serial fetal echocardiographic evaluations demonstrated stable left ventricular dimensions, preserved systolic function, impaired diastolic relaxation, and absence of endomyocardial fibroelastosis. Postnatal echocardiography confirmed hypoplastic aortic arch and coarctation. Following multidisciplinary evaluation, a biventricular repair strategy was selected. At 14 days of life, the patient underwent aortic arch reconstruction and partial atrial septal defect closure with preservation of a small therapeutic interatrial communication. Postoperative evolution was favorable, with progressive left ventricular growth and preserved function. At 2-year follow-up, echocardiography showed normalized mitral and aortic valve z-scores, good left ventricular systolic performance, and no evidence of myocardial fibrosis. Conclusions: This case highlights the value of serial fetal echocardiography in guiding individualized management of borderline left ventricle. Careful assessment of ventricular function and atrial septal physiology may support selection of a biventricular strategy in selected patients and contribute to favorable mid-term outcomes.