Platypnea-Orthodeoxia syndrome in a patient with atrial septal defect and concomitant aortic root enlargement.

We present the case of hypertensive and dislipidemic adult patient with a small ostium secundum atrial septal defect with trivial left-to-right shunt in whom an increasing enlargement of the aortic root and ascending aorta reversed the interatrial shunt causing severe dyspnea and oxygen desaturation, constantly elicited during upright position and relieved when he resumed the recumbent position (Platypnea-Orthodeoxia syndrome). Catheter-based closure of the interatrial communication was associated with an immediate increase in systemic saturation and long lasting marked clinical improvement.