syncopy episodes/dizziness

Hello,
I occasionally have episodes of feeling like I'm on the verge of fainting. Also have episodes of dizziness. When I get these episodes I go to the ER and get checked. EKG's, VS, bloodwork are normal. I've also had a nuclear stress test, and echocardigram fairly recently. Also an MRI, and MRA has been done a couple years back which again were normal. The physician's feel this is stress related. I'm pretty familiar with the "fight or flight response". When this last  episode occured, my ER BP was 135/86, and heart rate was 65. I am not hyperventilating when these occur. Instead, my respirations are bradyneic rather than increased, How can it be anxiety/panic attack - which is attributed to catecholamine hyperactivity when my VS remain normal????

[Divenurse]

The hyperactivity is in the brain, acting more as an physcological effect rather than an physical effect.

[Divenurse]

Wow.. Ok I was up for 24hrs. Theres more to it than this..l'v had 2 pts this month with syncopy and it's a very strange condition. Both cases had cbcs, cbgs WNLs and good VSs. There are so many diff. minut specific triggers. Catecholamine usually doesn't effect Vs.