High heart rate at 12.5 weeks?

PumpkinC
I just had a 12.5 week ultrasound and all looks good (check out that little cutie!).  However the baby's heart rate was 185 and then a few minutes later was 178.  The doctor says she's not worried at all but I read some stuff about a high heart rate indicating a possible chromosomal abnormality.
EDIT: I should add that baby was wiggling around like CRAZY during the ultrasound. Maybe that activity increased the heart rate??
Did anyone else have a heart rate around 180 in the 12 or 13 week range?   What ended up being the outcome for your baby?
Thanks,
A Nervous Mama