Platypnea-Orthodeoxia Syndrome: A Rare and Treatable Cause of Positional Dyspnea

Platypnea-orthodeoxia means low oxygen saturation and dyspnea in the upright posture which improves on lying down. The causes can be classified into the intrapulmonary shunt, intracardiac shunt, and ventilation-perfusion mismatch. A 62-year-old male presented with shortness of breath, which had worsened over a period of one year. Various investigations were done to rule bacterial, viral infection, pulmonary embolism, and other respiratory and cardiac causes. The initial echocardiogram showed an ejection fraction of 55%. The patient was observed to be having dyspnea only in the upright position. In the recumbent position, the dyspnea disappeared with a marked improvement in oxygen saturation. A repeat echocardiogram with a bubble study was done which showed an atrial septal defect. Surgical closure of the defect was performed which improved the patient's oxygen saturation to baseline normal. This case demonstrates that a vigilant approach is required in cases of dyspnea, keeping in mind the not-so-common phenomenon like platypnea-orthodeoxia syndrome.