Platypnoea-orthodeoxia syndrome in association with an ascending aortic aneurysm.

Platypnoea-orthodeoxia syndrome is a uncommon condition presenting with dyspnoea and cyanosis that are characteristically worse in the upright posture and improved by lying supine. We present the case of a patient with a thoracic aortic aneurysm and a patent foramen ovale who presented with platypnoea-orthodeoxia syndrome. Diagnosis was established using transoesophageal echocardiography. We suggest a mechanism for the development of dyspnoea and hypoxia in patients with this disorder.