I Get Very Anxious When I Go To The Doctor

I get very anxious when I go to the doctor and my blood pressure is usually high but when I take it at home it's fine. I have to go for some heart tests soon and I'm already getting so anxious - the anxiety makes my heart race and I worry so much about the prospect of this. I wish I could get past these feelings and deal with this situation rationally. Is there anything you can suggest to help alleviate this problem?