Platypnea and orthodeoxia: surgically corrected dyspnea with recurrence.

Platypnea is a clinical syndrome of dyspnea worsened by assuming an erect position and is associated with a postural arterial oxygen desaturation known as orthodeoxia. The clinical incidence of this syndrome may be underestimated by its occurrence in the medical literature. Several subgroups have been identified: patients with basal pulmonary vascular shunts; patients with intracardiac shunts, generally atrial, and who often have loss of lung volume; and patients without detectable shunts. Severe congestive heart failure may accentuate an occult shunt. When a patient presents with platypnea and/or orthodeoxia, a careful search should be made for underlying correctable disease such as atrial septal defects. Evaluation should include orthostatic contrast echocardiography, which in skilled hands may obviate the need for invasive cardiac catheterization in diagnosing underlying cardiac defects. Hemodynamic changes with changes in position have been difficult to study, but may play a significant role in the pathogenesis of this syndrome and, ideally, should be documented to clarify the underlying pathophysiology.