Treatment of Platypnea-Orthodeoxia Syndrome in a Patient with Normal Cardiac Hemodynamics: A Review of Mechanisms with Implications for Management.

Platypnea-orthodeoxia syndrome is a rare entity characterized by dyspnea and hypoxemia in the sitting position and usually resolved by lying down. Although it is not well understood, it is thought to be associated with either intracardiac or extracardiac factors. Within the group of intracardiac etiologies, it typically occurs in the presence of right heart failure or elevated right-sided filling pressures. When right heart failure is absent, platypnea-orthodeoxia is thought to be due to either anatomic changes that produce a baffle-directing flow across an atrial defect or to posture-dependent right-to-left pressure gradients. We report this case of a patient with no prior diagnosis of heart failure who presented to our hospital with 6 months of New York Heart Association class IV dyspnea and recent paradoxical embolus across a patent foramen ovale (PFO). Platypnea-orthodeoxia syndrome was diagnosed clinically. Transesophageal echocardiography revealed bidirectional shunting across the PFO. In the catheterization laboratory, invasive hemodynamics showed normal right and left atrial pressures and normal pulmonary arterial pressures. An Amplatzer Cribiform occluder device (AGA Medical Corp.) was used to close the PFO, completely curing the patient's symptoms. This is a novel case of subacute-onset severe platypnea-orthodeoxia associated with paradoxical embolus occurring while seated in the upright position. The cause of the patient's symptoms may have been progressive kyphosis or to increased pulmonary tidal volumes. Evaluation for platypnea-orthodeoxia is important in cases of occult dyspnea because the condition may be cured by closing the anatomic defect, as it was in this case.