Do not worry my friend there are many websites to explain this. I use to be just like you and this isnt ment to sound offensive in anyway but I use to worry that I was going to die and stuff. Well I looked up a lot of websites about my health so I have a pretty good look at these things. Anxiety does make your heart rate increased also if you have been drinking things with caffen in it that will inrease the heart rate. I think you have nothing life threatning to worry about. The main thing people think about with their heart is that they are going to have a heart attack and die. Well you are still young and you said your health and blood preassure is good. If you notice chest pain or pain in your shoulder blades or your neck then you should ask a doctore about heart disease totally doubt you have anything wrong with you tho. Also machines can greatly vary in results remember that. Get an offical reading if you are really worried. If you seem to worry and panic a lot ask your doctore about zoloft it will calm you down