atrial septal defect patent foramen ovale MONDO:0020439 patent foramen ovale (disease) HP:0001655 NANDO:2200266 MEDGEN:8891 icd11.foundation:1618980674 patent foramen ovale Orphanet:99108 MedDRA:10016982 ostium secundum type atrial septal defect NCIT:C34619 MESH:D054092 A persistent opening in the atrial septum after birth. While a normal part of fetal circulation, the foramen ovale should close once the newborn begins breathing and the pressure in the left atrium exceeds that of the right atrium. While a PFO is generally asymptomatic, it can lead to the passage of clots from the venous circulation into the artierial circulation, resulting in paradoxical emboli, and possible strokes. DOID:13620 UMLS:C0016522 patent foramen ovale (disease)