Rare Case of Paradoxical Embolism Through Anomalous Systemic Vein-to-Pulmonary Vein Connection: When Zebras Are Zebras.

We report a unique case of a congenital anomalous systemic vein-to-pulmonary vein connection with bidirectional flow causing paradoxical embolic stroke. A 64-year-old woman with no significant medical history presented with a multiterritorial embolic stroke after ankle fracture surgery. Computed tomography (CT) revealed occlusion of the left middle cerebral artery (MCA) and ischemia in the right MCA territory. Successful endovascular clot retrieval was performed, targeting the left MCA occlusion. Extensive investigation identified a rare connection between the right lower pulmonary vein and suprahepatic inferior vena cava, confirmed through transesophageal echocardiography, CT pulmonary angiogram, and invasive angiography. This connection facilitated right-to-left shunting, leading to paradoxical embolism. The connection was closed successfully with an Amplatzer vascular plug, eliminating the shunt. This case underscores the importance of considering rare anatomical anomalies in cryptogenic stroke and demonstrates the feasibility of device closure for managing such connections to prevent recurrent embolic events.