Tilt table test

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

A tilt table test is a medical procedure often used to diagnose dysautonomia or syncope. Patients with symptoms of dizziness or lightheadedness, with or without a loss of consciousness (fainting), suspected to be associated with a drop in blood pressure are good candidates for this test.

Concept behind the tilt test

The procedure tests for causes of syncope by attempting to cause syncope by having the patient lie flat on a special table or bed while connected to ECG and blood pressure monitors. The table then creates a change in posture from lying to standing.

Indications

• Recurrent episodes of syncope in the absence of organic heart disease.
• Recurrent episodes of syncope in the presence of organic heart disease after cardiac causes of syncope have been excluded.
• Unexplained single syncopal episode in high risk conditions (eg, occurrence or potential risk for physical injury or occupational hazard).
• When considered of clinical value to demonstrate patients susceptibility to vasovagal syncope.
• The test might also be considered in the following clinical setting.
  • To differentiate syncope with jerky movements found in epilepsy.
  • To evaluate patients with recurrent and unexplained falls.
  • In patients with psychiatric diseases with frequent syncopal episode.

Contraindications

• Patients who have orthostatic hypotension at baseline.

Preparations

Before actually taking the test, the patient may be instructed to fast for a period before the test will take place, and to go off of any medications he or she is taking. On the day of the tilt table test, a patient may be monitored using an electrocardiogram (ECG) while lying down. Some facilities insert an intravenous line in case the patient needs to be given medication quickly; however, this may influence the results of the test and may only be indicated in particular circumstances.

Procedure

Protocol

A variety of protocols have been described for the test that differ in the following way:

• In the angle of tilt (60 to 90º).
• In the duration of tilt (10 to 60 minutes).
• The administration of isoproterenol.

Steps of the procedure

• A tilt table test can be done in different ways and can be modified for individual circumstances.
• In some cases, the patient will be strapped to a tilt table lying flat and then tilted or suspended completely or almost completely upright (as if standing).
• Most of the time, a patient is suspended at an angle of sixty to eighty degrees.
• In all cases, the patient is instructed not to move. Symptoms, blood pressure, pulse, electrocardiogram, and sometimes blood oxygen saturation are recorded.
  • Heart rate and symptoms are recorded every 3-5 mins.
  • ECG is continuously recorded.
  • Blood pressure can be recorded in 2 ways:
    • Beat to beat finger arterial monitoring.
    • Arm cuff every three to five minutes.
• Positive test findings are as follows:
  • Loss of consciousness/Fainting.
  • Significant fall in blood pressure or heart rate.
• Patient is brought back to supine position if asymptomatic, even after 20 - 45 minutes.
• European society of cardiology recommends a passive phase (i.e. upright with no isoproterenol or nitroglyerin infusion).
• In patient remain asymptomatic, the patient is given Glyceryl trinitrate or isoproterenol, to create further susceptibility to the test.

Isoproterenol infusion

• A second tilt test is done if patient remains asymptomatic during the above mentioned test.
• After infusion, patient is placed in the head-up tilt position for an additional 15 to 20 mins.
• Role in tilt test: By activating β1-receptors on the heart, it induces positive chronotropic, dromotropic, and inotropic effects.

• Recommended dose: The infusion is usually titrated from 1 to 3 mcg/min to increase the heart rate by 20-25% above baseline.
• Special Precautions: Controlled infusion should not be performed in patients with coronary artery disease, as it could lead to angina and serious arrhythmia.

Diagnosis

A tilt table test is considered positive if the patient experiences symptoms associated with a drop in blood pressure or cardiac arrhythmia. A normal person's blood pressure will not drop dramatically while standing, because the body will compensate for this posture with a slight increase in heart rate and constriction of the blood vessels in the legs.

If this process does not function normally in the patient, the test could provoke minor symptoms to a very severe cardiac episode, depending on the person. A common side effect during tilt table testing is a feeling of heaviness and warmth in the lower extremities. This is due to blood pooling in the legs and, to onlookers, the patient's lower extremities may appear blotchy, pink, or red. Dizziness or lightheadedness may also occur. Tilt table testing could provoke fainting or syncope as this is the purpose of the test and it may not be appropriate, or indeed possible to stop the test before this occurs as the drop in blood pressure or pulse rate associated with a faint can come on in seconds, This is why the patient's blood pressure and ECG should be continuously monitored during the test. In extreme, rare cases, tilt table testing could provoke seizures, or even prolonged asystole. If at any time in tilt table testing, a patient loses consciousness, he or she will be returned to a supine or head down position and will be given immediate medical attention, which could include being given fluids or perhaps atropine or adrenaline.

External links

• 2004 European Society of Cardiology Guidelines on Management (Diagnosis and Treatment) of Syncope.
• University of Michigan: Tilt Table Testing
• Tilt Table Testing