My mild panic attacks include a rapid heartbeat and a mild lightheaded feeling.
I can easily get rid of them by concentrating on my breathing, slow, shallow breaths, in-out-in-out, nice and easy.

My moderate panic attacks include rapid heartbeat, dizziness, a tightening in my chest, feeling like I'm having an asthma attack, moderate hyperventilation, and sometimes a wave of prickly heat over my arms and/or a twinge of chest pain.

Severe panic attacks include all the symptoms of a moderate attack, only more severe and longer lasting, and accompanied by the feeling that I was going to die.

I used to get severe heartburn when I was stressed, but it did not accompany my panic attacks. Turns out that my years of heartburn were related to my gallbladder. I've not had any problems since having it removed.