Echocardiographic Features and Clinical Outcomes of Functional vs. Anatomical Pulmonary Atresia with Intact Ventricular Septum in Neonates

(1) Background: Functional pulmonary atresia (FPA) and pulmonary atresia with intact ventricular septum (PA/IVS) are rare neonatal congenital heart diseases with similar early clinical manifestations but distinct pathophysiology and treatment strategies, making early and accurate differentiation clinically important. (2) Methods: This single-center retrospective study included 43 neonates diagnosed with FPA (n = 12) or PA/IVS (n = 31) between December 2016 and March 2025. Echocardiographic parameters and clinical data were compared between groups, and receiver operating characteristic curve analysis was performed to evaluate the usefulness of selected echocardiographic indices for differentiation in clinical practice. (3) Results: Compared with PA/IVS, neonates with FPA exhibited significantly larger right atrial area, relatively better preserved right ventricular development, larger patent ductus arteriosus diameter, and lower peak tricuspid regurgitation velocity. Several parameters, including right atrial area and the right-to-left ventricular ratio, demonstrated strong between-group discrimination in this cohort. Clinically, most FPA neonates were managed conservatively with favorable outcomes, whereas PA/IVS neonates required surgical intervention and experienced higher perioperative mortality. (4) Conclusions: FPA and PA/IVS differ significantly in right heart morphology, hemodynamic characteristics, and management strategies. A comprehensive multi-parameter echocardiographic evaluation demonstrated discriminatory ability in this cohort, facilitating appropriate treatment decisions and potentially helping to avoid unnecessary high-risk surgical interventions.