The little boy is almost 2 years old now. And, if you happen to ask him who’s Superman, his little index finger will point to the place where his new heart beats.

It's anyone's guess whether Zach Shepardson really thinks of himself as the iron man. What's for sure is, at just 22 months, the Milton toddler is part of a growing number who are surviving congenital heart defects and will need life-long monitoring to insure that his heart continues to work well.

It used to be that babies born with serious heart defects like little Zach died in childhood. But, with the advent of such medical interventions, that's rarely the case any more, said Dr. Brian Kogon, chief of cardiothoracic surgery at Children's Healthcare of Atlanta's Sibley Heart Center. Not only are children living longer, he said, they're entering adulthood.

That's the good news. There's bad news , too. To read more about congenital heart defects, click here.