Palpitations is one of the more frightening panic attack symptoms as you may think that your heart is about to give up. Your autonomic nervous system controls your breathing and heart rate, amongst others. You don’t have to think about it. During high emotions such as a panic attack, your sympathetic nervous system responds to prepare for a fight or flight. It is the sympathetic nervous system that is causing your heart to race. Although unpleasant, it won’t harm you.