What Is The Treatment For Irregular Heart Beat In A Child?

the other night, i happen to listen to my 4 year old child heart while he was asleep. he was sick at the time, His heart beat was irregular, slow and seem to stop at time. I whent and ask my husband to listen to his heart too and he did and feel is pulse aslo. he heard the same missing beat and irregular heart beat as I had. It was quite enought to give us a scare so we bought it to the emergency hospital. but by the time we got there, our son is fully awake and his heart beat was fast and normal. but we are still worry. so we got him at the clinic today to see a pediatricians and he told me that his heart his fine and not too worry. what could be the cause of this? also it brought back to my memorry that my son did told me in two occasion in the past (his words)- maman, last night, I stop breathing... It woke me up and then I just told my brain to breath again.... is there are not an explanation to this? should we worry more and demande for more test?