I experience somewhat the same thing. I feel my heart is beating really hard all the time. I also feel my pulse in the lower part of my neck right where there is a soft spot and this bothers me. I think when you suffer from panic you are so internally focused on so hypervigilant that everything in your body is magnified. I also have electricity/vibrating feelings throughout my body all day and even when I try to sleep. I think it helps to know others experience this as well.
But the bottom line is that we're afraid something is terribly wrong with us and that we're going die. For me, it is the fear of sudden death - something I would not have control over. In my mind, I feel it is only a short matter of time before I die and I'm desperately seeking a diagnosis by visiting many doctors. No diagnosis comes, everything is okay, but the symptoms remain. So the cycle goes on. I do try to challenge my thinking by changing the thought from "what if something is wrong with me" or "what if I die" to "what if absolutely nothing is wrong me", "what if I'm really okay", "what if I look back on this two years from now and think, boy I wasted some valuable days in that fear".
It's hard but it helps. Well, I will stop rambling.
God Bless
Sherri