Platypnea-Orthodeoxia Syndrome: A Case of Chronic Paroxysmal Hypoxemia

Persistent Right Venous Valve: Insights From Multimodality Imaging

Anatomic variants in the right atrium are under-recognized and under-reported phenomena in cardiac imaging. In the fetus, right atrium serves as a conduit for oxygenated blood to be delivered to the left heart bypassing the right ventricle and the nonfunctional lungs. The anatomy in the fetal right atrium is designed for such purposeful circulation. The right and left venous valves are prominent structures in the fetal heart that direct inferior vena caval flow towards the foramen ovale. These anatomic structures typically regress and the foramen ovale closes after birth. However, the venous valves can persist leading to a range of anatomic, physiological, and pathological consequences in the adult. We describe various presentations of persistent venous valves, focusing on the right venous valve in this illustrated multimodality imaging article.

Platypnea-Orthodeoxia Syndrome: Rare or Under-Diagnosed Syndrome? 3 Case Reports and a Literature Review

Platypnea-Orthodeoxia Syndrome (POS) is dyspnea and hypoxemia in the upright position that improves in the supine position. Cardiac POS is predominantly caused by congenital interatrial communications (CIC) paired with changes in the thoracic anatomy, allowing orthostatic right to left cardiac shunting. High suspicion, especially with hypoxemia without significant pulmonary disease, that does not easily correct with supplemental oxygen, should lead the clinician to obtain echocardiographic imaging, documenting right to left shunting, typically through a patent foramen ovale (PFO). Transcatheter closure of the CIC is highly successful in relieving symptoms of dyspnea and resolving hypoxemia in the majority of patients.

Patent foramen ovale and ascending aortic aneurysm causing the platypnea-orthodeoxia syndrome

Patent foramen ovale (PFO) is present in about 25% of the population. Platypnea-orthodeoxia syndrome (POS), which is dyspnea and hypoxemia in the upright position that is relieved when supine, is a rare manifestation of PFO. We describe a case of a 74-year-old woman who presented with new-onset hypoxia. A PFO and a dilated aorta causing POS were found on workup. Symptoms were resolved after undergoing percutaneous PFO closure. This case highlights the mechanism by which an ascending aortic aneurysm can alter hemodynamics through an existing PFO, leading to symptoms of a previously clinically insignificant PFO, and emphasizes how early recognition of POS allows for appropriate intervention.