I've heard of people getting faint when raising their symptomatic arm over their head, but that's not me:

If I let my left arm hang down at my side, I get lightheaded. If I do this long enough, I eventually get chest pains. My chiro had trouble finding my pulse when the arm hung down.

If I raise the arm above my head, it begins to lose circulation in less than 15 seconds. This does not exacerbate my lightheadedness, it might even lessen it.

If I prop my left arm up to be parallel to the floor, I get a nice balance which reduces symptoms in both the arm and the head. My chiro felt my pulse come in when he lifted the arm parallel.

What is this? Does anyone have the same pattern?