Platypnea-orthodeoxia diagnosed by sitting transesophageal echocardiography.

Platypnea-orthodeoxia is a rare syndrome presenting with dyspnea and cyanosis induced by an upright position and relieved by recumbency. We report a patient with an excessively enlarged aortic root who had critical hypoxia due to a paradoxical shunt through the patent foramen ovale only when seated. The postural changes of the shunt, caused by changes in posture, were dynamically detected by transesophageal Doppler echocardiography. We believe that this syndrome should be considered when patients with aortic root dilatation present with inexplicable hypoxia, and that transesophageal Doppler echocardiography in the sitting position can be useful for detecting platypnea-orthodeoxia syndrome.