Partial anomalous pulmonary venous connection to superior vena cava that overrides across the intact atrial septum and has bi-atrial connection in a 75-year-old female presenting with pulmonary hypertension

BACKGROUND Partial anomalous venous connection (PAPVC) is a rare congenital heart disease where the blood flow from one or more pulmonary veins (but not all) returns to the right atrium or systemic venous circulation and is often associated with a sinus venosus atrial defect (SVD). Transthoracic echocardiography (TTE) can provide limited information for this anomaly and the diagnosis of this congenital defect has been a clinical challenge. CASE PRESENTATION We report here a case of a 75-year-old female with adult-onset pulmonary arterial hypertension (PAH), hypoxemia and right-sided chamber dilatation. The diagnosis of PAPVC was made incidentally by multidetector computed tomographic angiography (MCTA) that was performed to exclude pulmonary embolism. In this type of PAPVC, the atrial septum is intact, the right upper pulmonary vein (RUPV) connects to the superior vena cava (SVC), and the SVC overrides across the atrial septum and has bi-atrial connection, all of which are clearly manifested by MCTA. CONCLUSIONS This case indicates the need to exclude a PAPVC and SVD in unexplained pulmonary hypertension, and MCTA is a reliable non-invasive imaging technique with high resolution and wide anatomic coverage. The case also demonstrates that the coexisting SVD with PAPVC is an anomalous venous connection instead of atrial septal defect (ASD) and its key feature is the overriding of SVC or IVC across the intact atrial septum.