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Case Reports
. 2024 May 28;16(5):e61260.
doi: 10.7759/cureus.61260. eCollection 2024 May.

A Rare Case of Platypnea-Orthodeoxia Syndrome in a Patient With Undiagnosed Atrial Septal Defect

Rei Sanai  1 , Tetsuo Hirata  2 , Toyoshi Yanagihara  1 , Meimi Okamoto  2 , Takato Ikeda  1 , Yuki Shundo  1 , Naoki Hamada  1 , Noriyuki Ebi  1 , Hiroyuki Inoue  1 , Shin-Ichiro Miura  2 , Masaki Fujita  1
Affiliations
Case Reports

A Rare Case of Platypnea-Orthodeoxia Syndrome in a Patient With Undiagnosed Atrial Septal Defect

Rei Sanai et al. Cureus. .

Abstract

Platypnea-orthodeoxia syndrome (POS) is a rare condition characterized by dyspnea and oxygen desaturation that worsens in the upright position and improves when lying down. We report the case of a 67-year-old male who presented with a 14-month history of dyspnea in the sitting/standing position. Despite treatment for suspected asthma, his symptoms persisted, and he was referred to our hospital for further evaluation. Physical examination and arterial blood gas analysis confirmed the presence of POS, with a significant decrease in PaO2 and SpO2 when moving from a supine to an upright position. Contrast-enhanced CT showed no obvious embolism nor arteriovenous fistula, and ventilation-perfusion scintigraphy demonstrated ventilation-perfusion mismatch with a right-to-left shunt fraction of 9.4%, without any focal defect. Transthoracic echocardiography with a microbubble test demonstrated a right-to-left shunt that increased in the upright position. Transesophageal echocardiography revealed an atrial septal defect (ASD) with an atrial septal aneurysm and the presence of an inferior vena cava valve, causing a bidirectional shunt. The patient was diagnosed with POS secondary to ASD and was referred for percutaneous closure of the defect. Following the procedure, the shunt resolved, and the patient's orthostatic oxygen desaturation improved. This case highlights the importance of considering POS in patients with positional dyspnea and the value of performing diagnostic tests, such as echocardiography, in different positions to identify the underlying cause. Early recognition and appropriate management of POS can significantly improve patients' quality of life and prevent complications associated with chronic hypoxemia.

Keywords: atrial septal defect; dyspnea; microbubble test; platypnea-orthodeoxia syndrome; right-to-left shunt.

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Conflict of interest statement

Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Figures

Figure 1
Figure 1. Pulmonary function, CT, and scintigraphy findings of the patient.
(a) The flow-volume curve of the patient shows a downward convex. X-axis: volume (L), Y-axis: flow (L/second). (b) An axial enhanced CT image of the chest shows no obvious pulmonary artery embolism. (c) Three-dimensional reconstructed contrast-enhanced CT images of the pulmonary vasculature, with red vessels representing the pulmonary arteries and blue vessels representing the pulmonary veins. No arteriovenous fistula is observed. (d) Ventilation and (e) perfusion scintigraphy show no focal defect but ventilation-perfusion mismatch with a right-to-left shunt fraction of 9.4%.
Figure 2
Figure 2. Atrial septal defect detected by transesophageal echocardiography.
(a) Transesophageal echocardiography performed in the supine position reveals an atrial septal defect associated with an atrial septal aneurysm. The diameter of the ASD measured is 13 mm. (b). Additionally, an inferior vena cava valve is visualized. LA = left atrium; RA = right atrium
See this image and copyright information in PMC

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