Platypnoea-Orthodeoxia Syndrome: An Intriguing Diagnosis

Platypnoea-orthodeoxia syndrome (POS) is an uncommon clinical entity characterized by dyspnoea and hypoxaemia induced by upright posture and relieved by recumbence. It is often associated with right-to-left shunting through a patent foramen ovale (PFO) or an atrial septal defect. We report the case of a 79-year-old woman with hypoxaemia initially attributed to a pulmonary infection but persisting after successful treatment. Being in the upright position triggered the hypoxaemia. A thoracic CT angiogram and ventilation/perfusion lung scan excluded a pulmonary embolism, but a transoesophageal echocardiogram with a bubble test showed a PFO with a right-to-left shunt, without pulmonary hypertension. The patient underwent percutaneous closure of the PFO which led to prompt symptom relief and full functional recovery. LEARNING POINTS: Platypnoea-orthodeoxia syndrome is an uncommon condition that should be suspected in the presence of unexplained positional hypoxaemia. A high level of suspicion is required and the diagnosis can be safely established by tilt-table transoesophageal echocardiography. Percutaneous closure of a patent foramen ovale is safe and effective even in elderly patients.