Uncovering an Easily Overlooked Cause of Dyspnea: Partial Anomalous Pulmonary Venous Connection of the Right Pulmonary Vein to the Superior Vena Cava Leading to Right Heart Enlargement.

This case report describes a rare variant of partial anomalous pulmonary venous connections (PAPVCs) in a patient who presented with an insidious progression of dyspnea on exertion as an adult, leading to the diagnosis of PAPVC. The patient had an anomalous right upper pulmonary vein connecting to an anomalous pulmonary-azygos trunk that connected to the cranial superior vena cava (SVC), producing a large left-to-right extracardiac shunt. The diagnosis of PAPVC was made after evaluating for causes of right heart chamber enlargement. This case highlights the importance of considering PAPVC as a potential cause of unclear etiology for exertional dyspnea, right-sided chamber enlargements, and intact atrial septum. The onset and severity of symptoms in patients with PAPVC depend on various factors, including the number of pulmonary veins, site of connection, pulmonary vascular resistance, atrial compliance, and the presence of other congenital heart defects. Therefore, clinicians should maintain a high level of suspicion for PAPVC in patients with these types of symptoms.