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Autonomic Nervous System

Tilt-table test

Tilt Table Test · Z13.88

The tilt table test (TTT) is an autonomic function test that diagnoses autonomic nerve-mediated syncope (neurocardiac syncope), orthostatic hypotension, and orthostatic tachycardia syndrome (POTS) by fixing the patient to a tiltable table and passively assuming an upright posture to monitor changes in blood pressure, heart rate, and symptoms.

AT A GLANCE

At a glance

The standing tilt table test is a standard diagnostic test to identify autonomic causes of unexplained syncope or dizziness when standing. Passive standing (without active muscle pump) reduces venous return and reproduces autonomic dysreflexia. The overall sensitivity is approximately 26-80%, depending on the indication, and the positive rate for diagnosing autonomic nerve-mediated syncope is high [1].

Definition and Overview

The tilt table test (TTT; or head-up tilt test, HUTT) is a test that systematically evaluates the sit-to-stand reflex of the autonomic nervous system. After fixing the patient to the electric table, manually tilt it to an upright position of 60 to 70 degrees and monitor changes in blood pressure, heart rate, and symptoms due to standing for at least 20 to 45 minutes.

Because passive standing reduces venous return without the action of lower limb muscle pumps, syncope or hemodynamic abnormalities are reproduced in patients with autonomic dysreflexia.

Indications

According to the European Society of Cardiology (ESC) guidelines, implementation is considered in the following cases:

  • Recurrent fainting of unknown cause (especially if it occurs when standing up or after eating)
  • Even a single syncope occurs in a high-risk situation (driving, hazardous occupation).
  • Possible POTS (orthostatic tachycardia syndrome)
  • Assess orthostatic hypotension (after ruling out structural heart disease)
  • Differentiating from psychogenic non-epileptic seizures (PNES)

Inspection Procedure

Standard manual standing steps

Have the patient lie down on the table and rest for at least 5 minutes, then measure baseline blood pressure and heart rate. Tilt the table at 60-70 degrees and hold it for 20-45 minutes while continuously monitoring blood pressure and heart rate.

drug-induced phase

If the passive standing phase is negative, nitroglycerin (0.3-0.4 mg sublingually) or isoproterenol is administered to increase sensitivity.

Interpretation of results

Positive reaction type

  • Vasovagal: decreased blood pressure and heart rate, loss of consciousness
  • Cardioinhibitory: The main response is a decrease in heart rate, bradycardia.
  • Vasodepressor: Main response is lowering of blood pressure, little change in heart rate.
  • Mixed: Both blood pressure and heart rate decrease

Orthostatic hypotension diagnostic criteria

A decrease in systolic blood pressure ≥ 20 mmHg or diastolic blood pressure ≥ 10 mmHg within 3 minutes after standing.

POTS diagnostic criteria

Increase in heart rate ≥ 30 beats/min within 10 minutes of standing (≥ 40 beats/min for ages 12 to 19) without a decrease in systolic blood pressure.

Contraindications

  • Severe aortic stenosis
  • Severe coronary artery disease or unstable angina
  • Hemodynamically unstable cases of cerebrovascular disease
  • Recent myocardial infarction (within 6 months)

Linkage with autonomic nerve complex test

The tilt-table test can comprehensively evaluate the overall state of the autonomic nervous system when performed together with other autonomic function tests such as heart rate variability (HRV) analysis, Valsalva maneuver test, and sweating function test, rather than performed alone.

QUESTIONS

Frequently asked questions

Q01When do I undergo a tilt-table examination?

It is administered when repeated syncope or presyncope of unknown cause (feeling like you are about to faint), severe dizziness when standing up, unexplained falls, POTS, or orthostatic hypotension is suspected. It is used to first rule out cardiac-caused syncope and then evaluate autonomically mediated syncope [1].

Q02Does the tilt-table test hurt?

This is a test in which the patient is laid down on a table, secured with a belt, and then tilted at 60 to 70 degrees. The test itself is painless. However, since the test is aimed at inducing fainting, dizziness, nausea, and fainting may occur, and it is performed in an environment where immediate response is possible.

Q03Do you actually faint during the test?

That's right. Since the purpose of the test is to induce and confirm autonomic syncope (neurocardiac syncope), a drop in blood pressure and syncope may occur. It is safe as it is fixed to the table, and in case of fainting, the table is immediately lowered horizontally to restore blood pressure.

Q04Are there any special preparations before the test?

Fasting for 3-4 hours before the test is recommended. Medications that can cause fainting (blood pressure medications, diuretics, etc.) may be temporarily discontinued according to the doctor's instructions before the test. On the day of the test, sufficient water intake may be prohibited, or conversely, a water stress test may be performed. Follow the referring doctor's prior instructions.

Q05If the standing tilt table test result is negative, does that mean there is no syncope?

No. The sensitivity of the test is approximately 26-80%, so a negative test result cannot be conclusive of the absence of autonomic syncope [4]. The diagnosis is made based on clinical features, symptom patterns, and results of other autonomic tests.

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This article provides general medical information and does not replace an individual diagnosis or treatment plan. Please seek a medical assessment if symptoms persist.

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