To Add....
When she was being admitted into the hospital while she was in the ER she started slightly fussing and her heart rate jumped up to 189 within seconds.
Dear Heath,
It is difficult for me to be able to say exactly what is going on here without evaluating your daughter directly. I will say that moderate-sized atrial septal defects (ASD) do not by themselves cause failure to thrive as severe as you are saying. I would expect that she would be out of breath and/or sweaty with feeds if this were the case, which you do not describe. Certainly ASDs can decrease appetite somewhat, but not to the extent that you are describing. Your cardiologist may be right UNLESS there is another structural cardiac defect in conjunction with the ASD. There are many reasons for failure to thrive, which need to be further evaluated and exhausted here.
As far as the color changes that you are describing, these are commonly seen in infants and young toddlers and has nothing to do with the heart. If it is persistent, though, it should be evaluated.