Refractory Hypoxemia Secondary to Patent Foramen Ovale Presenting With Platypnea-Orthodeoxia Syndrome

Patent foramen ovale (PFO) is a common congenital cardiac anomaly present in 20%-25% of adults and is usually clinically silent. In rare cases, it can result in significant right-to-left shunting and refractory hypoxemia, particularly in platypnea-orthodeoxia syndrome (POS). We describe a 59-year-old woman with chronic hypoxemic respiratory failure who developed worsening oxygenation despite high-flow supplemental oxygen. Comprehensive evaluation excluded primary pulmonary, vascular, and parenchymal etiologies. Contrast echocardiography demonstrated a PFO with early right-to-left shunting. Percutaneous closure resulted in immediate and sustained improvement in oxygenation, with liberation from supplemental oxygen.