I have just started having panic attacks a few months ago. The first symptoms were in my chest. My heart was going 180 beats a minute for no reason. Very odd sensation. I was taken to the ER and eventually was given a stress test and an EKG, everything came back normal. But I was convinced it was a heart attack. The chest pain and discomfort was undeniable. Now, I still have it though the palpitations have calmed down (I am on a beta blocker). I can feel my heart flutter. But KimmyDawn is very correct in her explanation of breathing. It is so important! During anxiety your breathing is shallow plus your body doesn't exhale properly. When I started becoming conscious of my breathing I realized I was hardly breathing at all. So I had to learn how to breathe too. Inhale deeply from the diaphragm, drop and relax your shoulders as you exhale and purse your lips to exhale slowly. There is a balance between having the oxygen and the carbon dioxide. When I began doing this even for a few minutes, I noticed a tremendous difference in the attack. It doesn't make me stop having them but it helps so much getting through them without calling the EMT's.
Jojuli