Mixed Inferior Sinus Venosus and Secundum Atrial Septal Defects with Mixed Partial Anomalous Pulmonary and Systemic Venous Drainage: Key Insights and Practical Implications.

Mixed atrial septal defects (ASDs) involving inferior vena cava (IVC)-type sinus venosus and secundum types and mixed partial anomalous pulmonary, systemic, and hepatic venous drainage are rare. We describe a 3-year-old acyanotic boy who presented with a large mixed inferior sinus venosus and secundum-type ASD. He exhibited an abnormal connection between the right upper pulmonary vein and the right atrium. Additionally, the IVC and a hepatic vein drained abnormally into the left atrium. The patient also had valvular and supravalvular pulmonary stenosis, as well as a small patent ductus arteriosus. The ASD was surgically closed using a pericardial patch, positioned lower than usual to reroute the IVC and hepatic vein flow into the right atrium. The surgery was successful, with no residual lesions or complications. The patient recovered without issues and was discharged smoothly. At the 6-month follow-up, the child's cardiac examination and oxygen saturation were normal. Furthermore, echocardiography confirmed normal drainage of the systemic and hepatic veins into the right atrium.