Is there a downside to keep a patent foramen ovale in a child?

Yes: Statistically there are up 1/4 people with a patent foramen ovale. Most are inconsequential. However, in a select few, these have been associated with migraine's, difficulty breathing, a rare syndrome called platypnea orthodeoxia syndrome and occult strokes.

Depends: It depends on the size of the opening and whether or not the child has symptoms. Ask you cardiologist.