Two questions:
1. What method did they use to look for an adrenal tumor?
2. How's your thyroid?
Normal:
-Feeling dizzy when standing up
-Blood pressure decreasing and heart rate increasing
Abnormal:
-Heart rate going from 80-90 to 140. That's a lot. It sounds like you have POTS (postural orthostatic tachycardia syndrome)
-Heart rate suddenly increasing to 160 bpm and maintaining this rate for a whole night. That sounds like SVT (sinus ventricular tachycardia)
Both of these conditions are related to some kind of autonomic dysfunction, which CAN be caused by a precipitating illness. Your illness (whatever it was) could have caused your body to develop this dysfunction.
Increased catecholamines could be from stress. Are you on any medications? Certain drugs can cause this too.
POTS diagnosis is based on EITHER a 30+ bpm increase **OR** a heart rate increase over 120 bpm. The way I see it, if you are on beta blockers, how can the cardiologist accurately assess this? Perhaps if you re-did the test while OFF the beta blockers, your heart rate will increase over 120 bpm- which meets the diagnostic criteria for POTS.
If I were you I would get a second opinion. Also, keep in mind- you must taper off of the beta blockers, never stop taking them abruptly.