A case report of platypnea-orthodeoxia syndrome: A rare condition found during diagnostic workup of a patient with embolic stroke of undetermined sources

Abstract

Platypnea-orthodeoxia syndrome (POS) is a rare condition wherein the magnitude of the interatrial shunt changes between the sitting and supine positions. We diagnosed POS in a case initially considered to be of embolic stroke of undetermined source and performed emergency foramen ovale closure as definitive management for the patient. In this case, additional risk factors for POS include spinal deformity, meandering of the aorta, and exclusion of the right atrium due to overextension. Transcranial color flow imaging is recommended for the diagnosis of POS because of its sensitivity, specificity, and non-invasiveness. Although POS is an important barrier to effective rehabilitation, early diagnosis and definitive management lead to dramatic clinical improvement.

Keywords: ESUS, embolic stroke of undetermined sources; Embolic stroke of undetermined sources (ESUS); Emergency foramen ovale closure; Interatrial shunt; PFO, patent foramen ovale; POS, platypnea-orthodeoxia syndrome; Platypnea-orthodeoxia syndrome (POS); TC-CFI, transcranial color flow imaging; TEE, transesophageal echocardiography; Transcranial color flow imaging (TC-CFI).

Fig. 1

Transcranial color flow imaging (TC-CFI). Microembolic signal (MES) found in the microbubble test (right middle cerebral artery) using TC-CFI (A). Increased shunt blood flow signal intensity was observed in the sitting position. After surgery, MES disappeared in the microbubble test (B).

Fig. 2

Transesophageal echocardiography (TEE). During TEE, the posture was changed from the supine position (A) to the sitting position (B).