I was born with the same defect and had noninvasive heart surgery to close it over a decade ago, shortly after the procedure was approved. I'm not sure it can be done for toddlers, though definitely at a young age (I was 12).

I don't remember what it is called (I believe it's a mini thorocatomy) but they used a camera through my esophagus and a catheder inserted through the vein in my leg to inject the device to close the hole with no open heart surgery, only a few days recovery time in the hospital, and a few months before I was finally able to play most sports.