Closed foramen ovale: a potential entrance to left atrium

The anatomy of the limbus and its relationship to the fossa ovalis were studied in 90 normal human hearts in an attempt to explain the clinical success of blunt trans-septal catheterization. Previously reported rates of patent foramen ovale (25-35% of adult specimens) were confirmed, well below the reported rate of success for blunt trans-septal catheterization (67-87%). A possible reason for this success is the fragile attachment of the fossa ovalis to its limbus in nearly all hearts without persistent patency.