Platypnea-orthodeoxia syndrome is characterised by hypoxemia and dyspnoea while upright that resolves when supine, typically associated with an interatrial communication. We present a case of platypnea-orthodeoxia syndrome associated with a sinus venosus atrial septal defect in a patient with multiple possible aetiologies of hypoxemia, including COVID-19 infection. Cardiac catheterisation with provocative maneuvers confirmed the diagnosis and symptoms resolved following defect closure. We suggest that in patients with platypnea-orthodeoxia syndrome, it is useful to obtain haemodynamic data while supine and upright.
Keywords: Atrial septal defect; COVID-19; hypoxaemia; platypnea-orthodeoxia.