My first one showed preventricular tachycardia because I was anxious. They let me sit up for a while (with the electrodes still attached and kind of talked me into calming down).
They did a second one and while it still showed sinus tachycardia (I have an artificial heart valve since childhood), they figured that was normal and it was not alarming for me.
As for my blood pressure, it remained high. We have a home testing monitor and I had to track my morning blood pressures for a few days. They were all in the 110 to 120 over 60 to 80 range, so heart problems and blood pressure problems were ruled out.
See if they can elevate your head slightly while they are doing the test (took five to ten minutes for me to get it . . . the lengthiest part was getting the little suction cups hooked up and taken off). I found that you feel less vulnerable if you are not laying completely flat.
Best of luck! I will be with you in thought.
Lindaru