Researchers are beginning to better understand if, when, and how to address this condition, which is linked to a newly recognized type of stroke.
In the womb, all fetuses have a foramen ovale (Latin for "oval hole") between the heart's right and left upper chambers (atria). This opening allows blood to take a shortcut within the heart rather than following a longer path through the lungs, which cannot work until they are exposed to air. After birth, when a newborn baby takes his or her first breath, the foramen ovale begins to close. Most of the time, it seals completely within a few months.
But in about a quarter of people, that doesn't happen. This anatomical variation is called a patent foramen ovale (patent means open) or PFO. Most people never know they have it, because a PFO doesn't cause any signs or symptoms. For the most part, the condition is harmless.
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