Platypnea-Orthodeoxia Syndrome in patient with patent foramen ovale, dilated ascending aorta and persisting eustachian valve: A case report

Platypnea-Orthodeoxia Syndrome (POS) is a rare condition characterized by dyspnoea and hypoxia in upright position and symptom relief in supine position. The etiology is multifactorial depending on an interatrial defect and a functional component, which increases the right-to-left shunting in upright position. We report the case of a 68-years-old woman known with hypertension, dilated ascending aorta, two minor strokes and one episode of transient ischemic attack, admitted with severe dyspnoea and desaturation to 71% without oxygen supply. The patient experienced worsening of symptoms in vertical position and relief when lying down. Initially, pulmonary embolism was suspected, but refuted by computed tomography and ventilation/perfusion scintigraphy. The scintigraphy demonstrated tracer activity in multiple organs, which indicated a right-to-left shunt. Transesophageal echocardiogram (TEE) demonstrated a patent foramen ovale and a persisting eustachian valve resulting in right-to-left shunting, consistent with POS. Right heart catherization demonstrated normal pulmonary artery pressure of 12 mmHg ruling out pulmonary hypertension before the patient underwent PFO occlusion and gained full recovery. When POS is suspected, postural provocation should be considered when performing TEE and right heart catherization to demonstrate worsening of right-to-left shunting in upright position. In the cardiology emergency departments, POS is a rare but important differential diagnosis to pulmonary embolism.