Possible underlying cardiac illness?

3 weeks ago my 2y10m old daughter had an episode where she was so nervous she passed out.  The pediatrician chalked it up as if this was normal behavior for a child in fear.   Since then, she has had a severe cold and ear infection where the diagnosing NP at the "minute clinic" had advised that she had heard an extra beating of my daughter's heart... An ekg was done the next day and was found to be normal.  Today, my child was diagnosed with pneumonia and when checking her O2 sat, I noticed her heart rate was 114 and dropped down to 76, only to soar back into the 90's and back down to 70's again with another jump to 119, this went on for a good 15 minutes all while i sat and watched.  My child appears to be sleeping peacefully at a 45 degree angle to help ease her coughing while at rest.  Is all of this normal?  

[Jeffrey R Boris, M.D.]

Dear Mom,

It is unclear to me what is exactly going on here without evaluating your daughter.  I can say that it is very normal to have what is called "respiratory variation", in which the heart rate goes up with breathing in and slows down with breathing out.  The heart rates that you report are normal for a two year-old, so that is not specifically concerning.  I can't say what happened regarding the passing out--that is not typical for a toddler/pre-schooler.  This may require further evaluation by a pediatric cardiologist.