In the short term, children can have trouble with pleural effusions (fluid building up around the lungs). This can require a longer stay in the hospital for drainage with chest tubes. To address this risk, some surgeons make a fenestration from the venous circulation into the atrium. When the pressure in the veins is high, some of the oxygen-poor blood can escape through the fenestration to relieve the pressure. However, this results in hypoxia, so the fenestration may eventually need to be closed by an interventional cardiologist.