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 defect and mixed partial anomalous pulmonary and systemic venous drainage

Abstract

Mixed atrial septal defects (ASDs) involving inferior vena cava (IVC)-type sinus venosus and secundum types, with mixed partial anomalous pulmonary, systemic, and hepatic venous drainage, are rare. We report a three-year-old acyanotic boy who presented with a large mixed inferior sinus venosus and secundum-type ASD. He had an abnormal connection between the right upper pulmonary vein and the right atrium. The IVC and a hepatic vein also drained abnormally into the left atrium. There was also valvar and supravalvar pulmonary stenosis and a small patent ductus arteriosus. The ASD was surgically closed with a pericardial patch, positioned lower than typical to reroute the IVC and hepatic vein flow into the right atrium. The surgery was successful without any residual lesions or complications, and the patient recovered uneventfully. Abnormal IVC and hepatic vein drainage into the left atrium may not result in systemic arterial desaturation when a large ASD is present. During the two-dimensional echocardiographic evaluation of mixed  ASDs, it is critical to meticulously address three key aspects: 1. a thorough examination of both the systemic and pulmonary venous connections and their drainage; 2. a detailed search for any associated congenital heart diseases; and 3. the extensive use of the sweeping technique to comprehensively assess the atrial septum, especially when three-dimensional echocardiography is not available. It is crucial to inform the cardiac surgeon about these findings before surgery to prevent unexpected post-operative hypoxemia due to the misdirection of the IVC and hepatic vein into the left atrium.