Can't Catch a Breath: A Case of Platypnea-Orthodeoxia Syndrome

Document Type

Conference Proceeding

Publication Date

10-2025

Publication Title

CHEST

Abstract

INTRODUCTION: Platypnea-orthodeoxia syndrome is a rare phenomenon characterized by hypoxia in an upright position and normal oxygen saturations when lying down, secondary to intra-pulmonary, or more commonly, intra-cardiac shunting. We present a case of a patient with worsening dyspnea on exertion over several years. CASE PRESENTATION: Our patient was a 77-year old female with history of atrial fibrillation (AF) and rheumatoid arthritis on methotrexate therapy who presented with dyspnea and hypoxemia. Her symptoms had progressively worsened over the past couple of years, and she was now oxygen-dependent on exertion. In the clinic, she was noted to be hypoxemic, with oxygen saturation in the 60-70% range. She was subsequently admitted for respiratory support and further workup to rule out primary lung pathology including interstitial lung disease secondary to methotrexate therapy and to evaluate for an intra-cardiac shunt. This included an unremarkable high-resolution CT thorax, multiple echocardiograms and right heart catheterizations, performed in supine position, without evidence of shunt physiology. Initial trans-esophageal echocardiogram (TEE) did reveal an aneurysmal atrial septum and two atrial septal defects—a patent foramen ovale (PFO) and an iatrogenic defect from a prior AF ablation. The overall shunt was predominantly left to right. Left heart catheterization was also largely unremarkable, with no significant right to left shunt. Despite maximum non-invasive respiratory support, patient continued to experience severe hypoxemia, notably when sitting up or standing. Repeat TEE performed with patient lying flat initially demonstrated predominately left to right atrial-level shunt that reversed to a massive right-to-left shunt with the head of bed elevated to 45◦. The diagnosis of platypnea-orthodeoxia syndrome was confirmed and patient subsequently underwent successful closure of the defects with a 30mm Gore septal occluder device. She was discharged 3 days later, with normal oxygen saturations on room air. DISCUSSION: The mechanism of platypnea-orthodeoxia syndrome in the setting of an intra-cardiac shunt likely involves a combination of anatomical and functional factors including bulging of the atrial septum with the Eustachian valve directing blood towards to atrial septum, an elongated aorta and changes in interatrial pressures [1,2]. Intra-pulmonary causes include arteriovenous malformations or parenchymal diseases leading to VQ mismatch [1]. Patients typically present with dyspnea on exertion, a symptom commonly seen in more prevalent conditions such as left heart failure or intrinsic lung disease. These comorbidities may obscure the diagnosis, making it more challenging to identify platypnea-orthodeoxia syndrome. CONCLUSIONS: Platypnea-orthodeoxia syndrome is a rare etiology of chronic exertional hypoxia that may be overlooked during the evaluation for intra-cardiac shunts, as diagnostic studies are typically performed with patients in supine position. Our case highlights the importance of maintaining a high index of suspicion and utilizing provocative maneuvers for uncommon diagnoses.

Volume

168

Issue

4 Suppl

First Page

A4700

Last Page

A4700

Comments

CHEST Annual Meeting, October 19-22, 2025, Chicago, IL

DOI

10.1016/j.chest.2025.07.2637

ISSN

0012-3692

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