Platypnea-Orthodeoxia Syndrome: Manifestation of a Patent Foramen Ovale

Platypnea-orthodeoxia syndrome (POS) is a rare clinical condition characterized by dyspnea and hypoxemia during orthostatism, with relief in the supine position. The diagnosis of POS requires a high clinical suspicion, and its etiology stems from the admixture of venous blood, poor in oxygen, with arterial blood via a shunt. A patent foramen ovale (PFO) is the most commonly encountered anomaly at the root of POS.  Here, we present the case of a 67-year-old female patient where suspected POS led to the diagnosis of a PFO, which was the cause of an ischemic stroke.