Atrial Septal Defect Presenting as Platypnea Orthodeoxia Syndrome

Platypnea orthodeoxia syndrome (POS) is an uncommon phenomenon characterized by dyspnea and arterial desaturation in an upright position improved with recumbency. It is due to an anatomical factor that allows for interatrial communication and a functional factor that promotes right to left shunting. Once identified, early intervention allows for rapid symptomatic improvement. This case highlights that among patients who present with positional hypoxia, POS should be considered as a possible etiology. Thorough evaluation is warranted to identify potentially reversible etiologies and guide management. Keywords: Platypnea orthodeoxia syndrome, Atrial septal defect, Amplatzer closure device