Racing Heart

Has anyone else experienced a racing heart??  I feel like my heart is beating so fast and hard.  It was so bad this morning and I started to feel light headed, sweaty, and panicky after getting out of the shower.  I called the doctor and they squeezed me in the afternoon.  My blood pressure and pulse were normal so she's sending me to a cardiologist tomorrow to get checked out.  I'm trying to relax and stay calm but no matter what I do my heart just feels like it's going to burst.