Abstract
BACKGROUND: Mitral valve dysplasia syndrome (MVDS) is a rare cardiac defect requiring accurate prenatal identification and appropriate counseling, delivery planning, and postnatal management. CASE SUMMARY: A 39-year-old woman underwent fetal echocardiography at 34 weeks' gestation owing to cardiomegaly and hydrops. Biatrial enlargement, mild to moderate atrioventricular valve insufficiency, dysplastic mitral valve apparatus, biventricular dilation with systolic dysfunction, endocardial fibroelastosis, hypoplastic aortic outflow, and severely restrictive atrial septum were attributed to MVDS. The plan for critical (class IV) delivery was modified with premature onset of labor at 36 weeks' gestation, leading to urgent cesarean section. Emergent balloon atrial septostomy was performed on the female neonate, followed initially by hybrid palliation and orthotopic heart transplantation at 4 months of age. DISCUSSION: Identifying distinct anatomical features of MVDS prenatally differentiates it from various types of hypoplastic left heart syndrome and guides appropriate delivery and neonatal management, resulting in favorable outcomes. TAKE-HOME MESSAGE: MVDS is a unique variant of hypoplastic left heart syndrome that is able to be diagnosed prenatally, with high perinatal morbidity and mortality requiring perinatal preparedness.