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SPACE: Pathophysiology of Platypnea-Orthodeoxia Syndrome With Aortic Aneurysm in 5 Steps
Ulrich Hanses1, Rico Osteresch1, Stephan Rühle1
1Bremen Institute for Heart and Circulation Research (BIHKF), Department of Internal Medicine II, Klinikum Links der Weser, Gesundheit Nord gGmbH, Bremen, Germany.
Background:
Platypnea-orthodeoxia syndrome is a rare clinical entity with posture-dependent hypoxemia.
Case Summary:
A 47-year-old woman presented with progressive dyspnea and positional hypoxemia. Multimodal imaging revealed a bicuspid aortic valve, an ascending aortic aneurysm, and a patent foramen ovale with persistent right-to-left shunting despite normal pulmonary vascular resistance. The aneurysmal aorta displaced the cardiac axis, compressed the interatrial septum and right atrium, and, in combination with a prominent Eustachian valve, promoted venous flow across the foramen ovale. Surgical replacement of the ascending aorta and aortic valve, with concomitant closure of the patent foramen ovale, resulted in complete resolution of hypoxemia.
Discussion:
This case highlights the interplay of structural and flow-related mechanisms and introduces the concept of the SPACE framework (shunt, patent foramen ovale, axis deviation, compression, and Eustachian valve) in patients with aortic aneurysm.
Take-Home Message:
In patients with positional hypoxemia, systematic evaluation of the SPACE factors may help identify treatable intracardiac shunting.
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