Oxygen-Refractory Platypnea-Orthodeoxia Syndrome Requiring Urgent Surgical Closure: A Dynamic Assessment.

BACKGROUND

Platypnea-orthodeoxia syndrome (POS) causes posture-dependent hypoxemia due to right-to-left shunt, and it may be underestimated by routine evaluation.

CASE SUMMARY: An 84-year-old woman developed oxygen-refractory, posture-dependent hypoxemia during facial cellulitis and after contracting COVID-19. Transesophageal echocardiography identified a large patent foramen ovale with dynamic right-to-left shunt. Provocative assessment using invasive oximetry under a semi-sitting position and abdominal compression demonstrated a decrease in pulmonary-to-systemic flow ratio from 0.66 to 0.59. Because an intrahepatic inferior vena cava with focal narrowing rendered transcatheter closure infeasible, urgent surgical patent foramen ovale closure was performed, resulting in rapid improvement in oxygenation.

DISCUSSION: Dynamic, flow-driven POS may be underestimated by routine evaluation, and provocative assessment is essential in guiding urgent surgical closure when transcatheter intervention is infeasible.

TAKE-HOME MESSAGES: Provocative transesophageal echocardiography and invasive oximetry can identify POS when routine evaluation is inconclusive. Surgical closure should be considered when transcatheter closure is anatomically infeasible.