Mojadidi MK Ruiz JC Chertoff J Zaman MO Elgendy IY Mahmoud AN Al-Ani M Elgendy AY Patel NK Shantha G Tobis JM Meier B 2019 Patent foramen ovale (PFO), an embryonic remnant of the fetal circulation, is present in 20-25% of adults. Although recent observational studies and clinical trials have established the link between PFO-mediated right-to-left shunting with cryptogenic stroke and migraine with aura, the role of a PFO in exacerbating hypoxemic medical conditions (ie, sleep apnea, chronic obstructive pulmonary disease, pulmonary hypertension, platypnea-orthodeoxia, pulmonary arteriovenous malformation, high-altitude pulmonary edema, and exercise desaturation) remains less understood. PFO-mediated hypoxemia occurs when deoxygenated venous blood from the right atrium enters and mixes with oxygenated arterial blood in the left atrium. Patients with an intracardiac right-to-left shunt may have profound hypoxemia out of proportion to underlying primary lung disease, even in the presence of normal right-sided pressures. The presence of right-to-left cardiac shunting can exacerbate the degree of hypoxemia in patients with underlying pulmonary disorders. In a subset of these patients, percutaneous PFO closure may result in marked improvement in dyspnea and hypoxemia. This review discusses the association between PFO-mediated right-to-left shunting with medical conditions associated with hypoxemia and explores the role of percutaneous PFO closure in alleviating the hypoxemia. https://sonar.ch/global/documents/201501 eng info:eu-repo/semantics/altIdentifier/doi/10.1097/CRD.0000000000000205 info:eu-repo/semantics/altIdentifier/pmid/29570476 Cardiology in review. - 2019 Endovascular Procedures Foramen Ovale, Patent Humans Hypoxia Patent Foramen Ovale and Hypoxemia. http://purl.org/coar/resource_type/c_6501