[Echocardiography in patent foramen ovale]

Patent foramen ovale (PFO) is a flap-like opening between the primum and secundum atrial septum at the level of the fossa ovalis that may persist after birth. There is increasing evidence that PFO is the culprit in paradoxical embolic events in patients with ischemic stroke. Although medical or percutaneous treatment of PFO remains controversial, nowadays percutaneous treatment is widespread in clinical practice. Transesophageal echocardiography (TEE) is the gold standard in the diagnosis of PFO. This article describes how PFO is detected and how it needs to be properly described by echocardiography. PFO dimensions and the degree of right-to-left shunt should be measured. Moreover, septum primum and septum secundum characteristics, the association with an aneurysm of a fossa ovalis or with other atrial defects should be described as well as the presence of an atrial thrombus, a Chiari network or an Eustachian valve. Such information is of extreme value to predict embolic events and may influence further management.