You may be having palpitations. Are you on any meds? Do you go to a psychiatrist?
If your heart problems concern you, you may want to go to a cardiologist and have an EKG. That will detect any heart abnormalities and it is relatively cheap.
If you think this problem is anxiety related, go to a psych, if you already do not. Only meds, therapy, time, and a lifestyle change (no alcohol, eating healthy, exercise, etc) can resolve anxiety disorders.
Edited by Shakes to add: