We present a patient with pulmonary arterial hypertension requiring venovenous-extracorporeal membrane oxygenation for acute respiratory distress syndrome. Refractory hypoxemia secondary to right-to-left interatrial shunting via a patent foramen ovale was discovered. Right heart catheterization with invasive occlusion test heralded worsening right heart failure so closure was aborted. (Level of Difficulty: Intermediate.).
Keywords: ECMO, extracorporeal membrane oxygenation; HIV, human immunodeficiency virus; PAP, pulmonary artery pressures; PFO, patent foramen ovale; RA, right atrial; RV, right ventricular; VV-ECMO, venovenous-extracorporeal membrane oxygenation; pulmonary hypertension; right ventricle; right-sided catheterization.