Platypnea-orthodeoxia is an uncommon syndrome of dyspnea and hypoxemia induced by upright position, which is subsequently relieved by recumbency. The case reported involved a 75-year-old man with a seven days history of dyspnea in the upright position. The chest radiograph and CT scan demonstrated an elevated right hemidiaphragm. A surface echocardiogram with saline solution showed a patent foramen ovale (PFO) and atrial septal aneurysm. A pulmonary arteriogram was performed showing no evidence of pulmonary embolism and normal pulmonary arterial pressures. Later, he also developed dyspnea in the supine position and a transesophageal echocardiogram with contrast demonstrated a large right to left shunt through a PFO. The closure by a catheter-deployed double-umbrella device caused an immediate improvement in the patient's oxygenation.