What is partial anomalous pulmonary venous return (PAPVR)?
PAPVR occurs when part of the pulmonary venous system drains directly into the systemic venous circulation, creating a left-to-right shunt. It can occur in isolation or be associated with either an atrial septal defect (ASD) or a hypogenetic lung. When PAPVR is associated with an ASD (usually a sinus venosus defect), the right upper lobe pulmonary vein drains into the superior vena cava (SVC). When PAPVR occurs with a hypogenetic lung, it is a component of scimitar syndrome