Right-to-left atrial shunting associated with aortic root aneurysm: A rare cause of platypnea-orthodeoxia syndrome

Platypnea-orthodeoxia is a rare syndrome characterised by dyspnea and hypoxemia worsened on upright posture. We report the case of a 76-year-old man treated for lung adenocarcinoma who had developed severe hypoxemia due to right-to-left shunt through a patent foramen ovale (PFO). Diagnosis was suspected by systemic uptake of isotope during lung scintigraphy performed to eliminate pulmonary embolism. Arterial blood gas analysis in supine and upright positions demonstrated orthodeoxia. Contrast-enhanced trans-oesophageal echocardiography revealed a slightly redundant atrial septum and large right-to-left shunt through a PFO despite normal pulmonary pressure. Chest computed tomography and echocardiography showed a 59-mm aneurysm of the thoracic aorta. The opening of the PFO seemed to be the result of mechanical deformation of the atrial septum by aortic root dilatation and possibly by lung carcinoma. Transcatheter closure of the atrial defect has provided excellent results, including a rapid increase in systemic saturation and improvement of symptoms without any complications.