Hello, Welcome to Just Answer and thanks for your question. I'm glad they have found a reason for the fainting and other symptoms he was having. Have they discovered what kind of heart problem he has?
I'm so sorry I couldn't tell you what was wrong with your son other than he should be seen by someone who could examine him in person. I doubt the physicians who diagnosed him could have done any better without seeing him and ordering a whole phalanx of tests. I'm glad he now has a diagnosis. No doubt he will do better.