Platypnea-orthodeoxia syndrome due to PFO and aortic dilation.

A 75-year-old man had occasionally been referred to our hospital with sudden dyspnea due to unknown causes. He had a history of hypertension and polycystic kidneys and had undergone transcatheter pulmonary vein isolation for paroxysmal atrial fibrillation 2 years previously. Physical examination revealed normal heart sounds without murmurs and was otherwise unremarkable. Electrocardiography, chest radiography, and blood tests were also normal. Oxygen saturation was 98% on room air in the supine position, but once he sat up, oxygen saturation suddenly dropped, causing dyspnea. He was then admitted for further investigation. Continuous oxygen saturation monitoring showed that it decreased negligibly during standing or walking but decreased strikingly to 72% just after sitting or squatting. Chest computed tomography, spirometry, and lung perfusion scintigraphy showed no findings of lung disease or pulmonary embolism. Transthoracic echocardiography showed dilation of the sinus of Valsalva and ascending aorta without abnormal shunting, pulmonary hypertension, or ventricular diastolic dysfunction.