What happens during table tilt testing?

Tilt table testing is part of the work up for vasovagal syncope. It is also indicated in:

  • recurrent episodes of syncope when a cardiac cause has been ruled out
  • unexplained syncopal episode in a high-risk setting
  • to examine reflex syncope (and distinguish between orthostatic and reflex syncope)

I saw a case of a 26 year old who passed out after dinner with friends. According to her friends, she was shaking a little but came to spontaneously after a few minutes. Because her EKG and Holter and EEG were normal, she got a tilt table test. She actually started reporting lightheadedness after getting SL nitro, and she had to get fluids and put in the supine position. Her HR during the test was all over the place, 90s-130s, and changed really quickly, like 90 one second and then 102 the next, then 96, then 113. Dr. Sood said that people’s HR do change, but it’s usually more gradual and not that extreme, so this qualifies as sinus arrhythmia—she has primary sinus tachycardia. He postulated that her syncope was due to tachycardia itself, so put her on a low-dose beta blocker.

Tilt table testing has limited sensitivity and specificity. Some report that an individual can have a negative result one day, and then a positive result the next. But it is useful for drawing the following conclusions:

  • If reflex hypotension or bradycardia + syncope are induced, the test is diagnostic for reflex syncope.
  • If there is a progressive, slow decrease in systolic blood pressure (orthostatic response) with or without symptoms, syncope due to orthostatic hypotension is diagnosed.
  • When syncope is induced but there is no hypotension or bradycardia, this suggests psychogenic pseudosyncope.

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