Failure of closure of the foramen ovale results in which condition?

• A. Patent foramen ovale
• B. Coarctation of the aorta
• C. Tetralogy of Fallot
• D. Transposition of the great arteries

Answer: (A)

Blood flows through the foramen ovale in fetal life to bypass the nonfunctional lungs. After birth, rising left atrial pressure pushes the thin septum primum against the septum secundum, causing functional closure, followed by permanent sealing as tissues fuse. If this opening does not close, a patent foramen ovale remains, a persistent communication between the atria. This is often silent but can enable paradoxical emboli, potentially leading to cryptogenic stroke in some individuals. The other conditions listed involve different structural defects: narrowing of the aorta, a complex ventral septal defect with outflow obstruction and other features, and a discordant arrangement of the great arteries, respectively.