The foramen ovale is a small hole or channel in the wall between the top two heart chambers that allows oxygenated blood to mix in a baby before it is born. After a baby is born, the foramen ovale typically closes although for perhaps 20-30% of us, a channel persists and is termed a patent foramen ovale (PFO). In unusual situations, a clot from the veins of the body can pass across this channel and find its way into the brain circulation.

Last reviewed by a Cleveland Clinic medical professional on 05/18/2015.

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