Platypnea Orthodeoxia Syndrome with Patent Foramen Ovale and Positional Right to Left Shunt Despite Normal Right Sided Pressures
Journal of the American College of Cardiology
Platypnea Orthodeoxia Syndrome (POS) is characterized by dyspnea and hypoxemia exacerbated in the upright position and improved in the supine position. POS requires both a structural component with interatrial shunting and a functional component affected by recumbent and upright positioning.
An 84-year-old woman with history of known patent foramen ovale (PFO) with aneurysmal interatrial septum diagnosed 7 years ago and chronic obstructive pulmonary disease (COPD) not on home oxygen presented with new onset hypoxia at 82%. She was started on 5L supplemental oxygen with improvement to 95%. Transesophageal echocardiogram revealed PFO with right to left shunting and Chiari network with encroachment of right atrial (RA) wall by a dilated ectatic aorta, causing RA constriction. There was no evidence of elevated right heart pressure.
A right heart catheterization showed left to right shunt with normal pressures in the right atrium, right ventricle, pulmonary artery, and pulmonary capillary wedge. Pulmonary etiology was initially considered, but despite treatment with antibiotics and steroids for suspected COPD exacerbation, she continued to remain hypoxic with positional changes. A repeat limited transthoracic echocardiogram two weeks after admission redemonstrated right-to-left shunting. Given the cardiac anatomic variation, in context of continued episodes of hypoxia while sitting upright and improvement while lying recumbent, she underwent a percutaneous PFO closure with a 30mm Gore Cardioform Occluder device. Within hours of shunt closure, her oxygen saturations normalized to high 90s while on room air.
This case is a rare example of right-to-left shunting across PFO despite normal RA pressures. Although no complicating factors could be identified, we suspect her unique cardiac anatomical variation contributed to acute worsening of her condition. It also highlights the importance of considering the positional nature of the intracardiac shunt while interpreting the imaging or diagnostic tests.
Sumesh K, Jacob J, Khagendra D. Platypnea Orthodeoxia Syndrome with Patent Foramen Ovale and Positional Right to Left Shunt Despite Normal Right Sided Pressures. 2021;77(18):2477. Available from: https://doi.org/10.1016/S0735-1097(21)03832-8