What is patent foramen ovale?

Also known as: PFO.

A PFO is a hole in the tissue (atrial septum) that separates the heart's two upper chambers, (right atrium and left atrium). It's present in all babies before birth, and the opening allows oxygenated blood from the mother's placenta to bypass the baby’s non-functioning lungs and send oxygen to the baby's growing body. Typically (in 75%) it closes after a baby is born and breathes. When it doesn’t close, the persistently open hole is called a PFO.

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Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: 1/29/2019 3:21:13 PM