@burcidi-- Have you seen a cardiologist or a psychiatrist?
A routine check-up won't show irregularities with heart function. You need to see a cardiologist to make sure that there isn't an underlying condition.
The reason I suggest a psychiatrist is because people who experience a lot of anxiety can have throat palpitations. I used to have them too and it went away after I started psychological counseling and anti-anxiety medications. You might want to look into this if everything else is normal.