This is the case of a young female who was seen at our adult congenital heart disease and pulmonary hypertension service (Royal Brompton Hospital, London, UK) at the age of 17 years. She initially presented at the age of 4 years with increasing shortness of breath. At that time, there was differential cyanosis with clubbing and lower oxygen saturations in the toes (82%) compared with her fingers (95%). On echocardiography there was evidence of severe pulmonary hypertension and a large patent ductus arteriosus (PDA) with low velocity bidirectional shunting. She underwent cardiac catheterisation at the time which showed a pulmonary arterial pressure equal to that of the aorta.