Hi,Kept a check on your blood pressure .Also have your thyroid checked you may have a thyroid problem.Good luck.
your heart beats fast during sex that sounds pretty normal to me i think for most people thats normal. usually when people are having sex you get really excited thats proly why your hearts beating fast.but if it is real bothersome to you go to your doctor and explain this to him see what he says just to be on the safe side.