Accessory hepatic vein to pulmonary venous atrium as a cause of cyanosis after the Fontan operation.

The presence of an accessory hepatic vein to the pulmonary venous atrium should be considered in the setting of progressive cyanosis following the Fontan procedure. An inferior vena caval angiogram with "levo-phase" should demonstrate it. Surgical intervention or transcatheter occlusion should lead to prompt resolution of cyanosis.