How I do it: Novel technique to "Unmask" and treat congenital portosystemic venous connections in congenital heart disease.

Congenital portosystemic venous connections are rare vascular anomalies that connect the portal and systemic venous circulations. These vascular lesions can lead to complex and varied physiologic manifestations in single-ventricle patients as they progress through the various stages of palliation in the Fontan pathway. Specifically, these connections may be unmasked after a superior cavopulmonary anastomosis operation, but then "re-masked" after Fontan completion. We describe the complex physiology with an illustrative case report and present a novel method to unmask these pathologic connections after Fontan completion to facilitate transcatheter occlusion and resolve downstream symptoms.