Can anyone comment on the validity of tilt table testing when giving the patient something like nitroglycerine? After passing out a year ago, I've suffered from symptoms of lightheadedness, heat sensitivity, flushing, sleep disorders, abnormal sweating, hypersensitivity, heart palpitations, and several other symptoms intermittently. I had a tilt table test recently. During the initial tilting phase, I was not symptomatic. During the second phase, the doctor gave me a small dosage of nitroglycerine, which I've read is standard procedure with this test among lots of doctors to increase your adrenaline. At that point, I became very symptomatic--sweating, extreme lightheadedness, dizziness, nausea, shaking. BP and heart rate both went down. It took me a couple of hours after the test before I felt better. The doctor who did the test felt I may have POTS, another doctor who reviewed the test results felt I may have NMH, and a third doctor seemed to be dismissive of the results, although he agreed that I do have some type of tendency toward syncope. My question: what might it indicate when you're symptomatic during a tilt table only after getting something that increases your adrenaline? I seem to be symptomatic typically in warm environments. Heat sensitivity is the key symptom and trigger for me. Just standing in place for a long time doesn't necessarily trigger my symptoms, but if I'm in a warm environment, then that's when I experience strong symptoms. Has anyone else had a similar reaction to a tilt table test, or similar symptoms? I'm curious to hear from other people about this. Thanks for your feedback.