Herein we report a 21 year-old woman with a previously documented patent ductus arteriosus and Eisenmenger physiology. She presented with increasing cyanosis and exercise intolerance which could be explained by a new finding of right to left shunting through an interatrial communication. She was started on Bosentan therapy aiming to reduce the pulmonary pressure with consideration for heart-lung transplantation should any further deterioration occur.