Reversible platypnoea-orthodeoxia syndrome

Area of Science:

• Cardiology
• Pulmonology
• Medical Imaging

Background:

• Platypnoea-orthodeoxia syndrome (POS) presents as dyspnea and hypoxemia in the upright position.
• POS is typically caused by extracardiac shunts or dynamic accentuation of intracardiac shunts.

Observation:

• A patient presented with POS attributed to left lower lobe collapse secondary to bronchial stenosis from endobronchial tuberculosis.
• This collapse caused a mediastinal shift, unmasking a previously unrecognized intracardiac right-to-left shunt via a patent foramen ovale.

Findings:

• Gravity in the upright position likely increased stretching and widening of the patent foramen ovale, augmenting the right-to-left shunt.
• Bronchial stenting successfully restored left main bronchus patency, leading to left lower lobe re-expansion and mediastinal repositioning.

Implications:

• Resolution of POS following airway stenting suggests a novel mechanism for shunt-related hypoxemia.
• This case highlights the importance of considering extrinsic factors affecting intracardiac shunts in POS management.
• Findings may inform future treatment strategies for similar complex POS cases.