Perhaps it would be better to put the palpitations on the form whether they ask specficially or not. The reason is that if the dentist has to give you novacaine, which can cause an increased heart rate as it has adrenaline properties, you might feel palpitations as well.
I didn't know about this and had a root canal done. Of course the novacaine made my heart race and I got very anxious and flushed. I panicked and wanted to stop everything which we couldn't. Later the dentist said if I had mentioned the palpitations, I could have had a form of novacaine that has much less of the adrenaline properties and rarely causes those side effects. While the numbing is very effective and just as good as the regular, it does wear off sooner when you return home.
Anyway, do yourself a favor. Let the dentist know and that you would prefer to use the non-adrenaline form of novacaine in the future. It can be put on the front of your file...as mine is now.