What is the hole in an infants heart that heals itself called?

There's a few: Pre-birth, there are a couple ways blood goes around the normal circulation, and the hole between the upper chambers, the atria, is called the foramen ovale. That usually closes a few days after delivery. Sometimes there can be holes between the ventricles, the lower chambers. Those aren't supposed to be there, but they often will close on their own anyways, but should be monitored.

VSD or ASD: Vsd is a small hole between the two lower chambers and ASD is a hole between the upper chambers and most of them close on their own.