Patent Foramen Ovale in Adults With Right-to-Left Shunting: Clinical Significance, Diagnosis, and Contemporary Management

During fetal development, the foramen ovale is an important component of normal fetal circulation, allowing oxygenated blood to bypass the nonfunctional fetal lungs and supporting fetal growth and development. After birth, incomplete fusion of the septum primum and septum secundum may result in a persistent patent foramen ovale (PFO), which is present in approximately 25% of adults. Although most individuals remain asymptomatic, PFO has been recognized as an important contributor to paradoxical embolism and cryptogenic ischemic stroke. The clinical significance of PFO depends not only on its presence, but also on patient characteristics and anatomical features that influence the likelihood of right-to-left shunting and embolic events. High-risk morphology characteristics, including a large interatrial communication, elongated tunnel length, and prominent Eustachian valve or Chiari network, are associated with increased embolic potential. Advances in multimodality imaging, particularly contrast transesophageal echocardiography, have improved the diagnosis and anatomical characterization of PFO, while risk stratification tools such as the Risk of Paradoxical Embolism (RoPE) score and the PASCAL classification are important tools when determining whether a PFO is likely to be causally related to ischemic stroke. Treatment options for PFO are also largely related to the risk and morphology of the PFO, with age and risk of recurrent strokes impacting potential treatment options. Closure of PFO may not be recommended in all patients; however, percutaneous closure has become more prevalent in recent years due to its less invasive nature.