My daughter was diagnosed with one when she was 18 months. We then saw a Cardiologists at Children's who ran the EKG and every other test. Turns out the murmur was "innocent" (which is very, very common). Subsequently, she was diagnosed with a PDA (Patent Ductus Arteriosis) where a valve in her heart that clamps after birth, did not. We had to wait a year to see if she outgrew it. Meanwhile, she just had to receive a high dose of antibiotics prior to a dental treatment. A year later she still had the PDA, so it was clamped shut when she was 2 by a Cardiac Cauthurization. (I know I'm misspelling here.) That was a simple procedure. When she went back to the cardiologist a year later, everything was fine with the PDA, and even the murmur. She's 12 now and drives me nuts like a normal pre-teen. I was VERY, VERY scared back then, but knowing now what I do, I've learned the murmur wasn't something too scarey. I'm also glad she DID have it, as it lead us to the PDA.