Hi XvMercy, I am sorry I am so late in replying to your message. My little brother...well he isnt so little now (29) but when we were kids was diagnosed with a heart problem, Mitro Valve Prolape. He also had ADHD. My mother who is a cardiac nurse was very good at cordinating his care...anyhow, he was seen by a cardiologist for his heart condition and a psychiatrist who prescribed Ritalin at small doses for his ADHD. Both of his doctors kept in close contact regarding his treatment and care.
Now, as to weither or not the two go hand in hand I couldnt say. I would actually be more inclined to believe that they are very seperate issues but then again I am not a physician. Take care and please do keep us posted on how he is doing.