Have you been seen by a heart specialist? Your palpitations may have a physical cause, especially if you have been experiencing them for at least five months. But they may also be a consequence of anxiety. I am no specialist, but as far as I know your heart cannot be damaged by palpitations...At least not without an organic deficiency. It is true that constant palpitations cause your heart to work harder but I think it would be an extremely long period even before your heart being affected.
I suggest you go see a specialist. Meanwhile, check this out: http://www.Adaa.Org/gettinghelp/selfhelpte sts.Asp

I also get heart palpitations and have known several people who also got palpitations. I still get them now with my anxiety, but I also started getting them with my last pregnancy and went and had testing done and the cardiologist said they were from being pregnant and I was told that I have extra beats and that can cause them too.

The other people I knew who had them also had some testing done and were told that it was stress related, caffeine related and from lack of sleep.

I would talk to a doc to make yourself feel better, but alot of times palpitations have no known cause and are harmless from what I have researched.

Well,i am the same with you I reckon. I doubt that it caused by both mental and physical problems.

I get heart palpitations to the point that my chest hurt. I have even worn a heart monitor and done a stress test and they said nothing was wrong with my heart, that it is just anxiety. Just do some breathing exercises that will help your heart rate come down; such as breathing in and then letting your breath out very slowly. You can feel your heart rate come down and your anxiety go away. It helps me anyways. There are always those attacks you cannot control no matter what kind of breathing exercises you do though. I am sure everyone knows what those are.