Hi, I am 32 years old, I do have panic disorder but have been dealing with heart palpitations. They are getting more frequent, I am on propanolol 20 mg twice a day, which is not helping. I m worried because now I experience occasional biting in my chest when I have the palpatations. I have been checked, had an ekg down but that is it. Why do I feel like they are missing something? Should I be worried about the burning in my chest. I also get lightheaded and dizzy, and tired.