The authors report a 7-year-old girl with univentricular heart physiology who developed prolonged pleural effusion due to discrete narrowing of the proximal right pulmonary artery, and progressive cyanosis which resulted from leakage of the atrial baffle, multiple veno-venous collaterals after the lateral tunnel Fontan operation. Percutaneous balloon-expandable stent implantation was used to correct the right pulmonary artery stenosis with an excellent result. Cyanosis was improved by coil embolization of the collaterals and occlusion of the baffle leakage with Amplatzer septal occluder. This is the first successful report in Thailand.