SVT. Management of svt is very dependant on the substrate involved and the rate of svt and how persistance during the day or rare occurance. You need to see pediatric ep for this. If you are in houston i will be happy to see you in the university of texas health science center.
Go to ER. Even though babies may tolerate supra-ventricular tachycardia at rates above 240bpm for many hours it is imperative that he or she is seen at an er asap where they can obtain an ECG and give him medication by vein that will restore his hr to normal. The baby will most likely be started on daily medication after that and you should definitely follow-up with a pediatric cardiologist.