you'd know if you were having a heart attack.  *warm smile*

my anxiety/panic attacks made my heart beat really fast.  i'd also start feeling really hot and start sweating.  one of the things that helped me to calm down was to breathe into a napkin (same effect as breathing into a bag when hyperventilating). 

i also suggest talking to your primary care doctor and/or psychiatrist.  there are meds that can help you if your panic/anxiety attacks get so bad that you can't function normally.  (i take valium)