Tilt-Table Testing Technique

Updated: Mar 17, 2016
  • Author: James V Talano, MD, MBA, MM, FACC, FAHA; Chief Editor: Karlheinz Peter, MD, PhD  more...
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Technique

Approach Considerations

The tilt-table test involves placing a patient on a flat table with a foot support, then tilting the table upward for a period of time to observe changes in blood pressure and heart rate. The patient is initially positioned supine and horizontal on the table, then tilted by degrees to a completely vertical, upright position. During the study, blood pressure, heart rate, oxygen saturation, and cardiac rhythms are recorded and monitored for the end point of fainting, which indicates a positive tilt-test result. [7] The patient is also observed for signs and symptoms that would necessitate early termination of the study.

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Tilt-Table Testing

The following steps describe positioning and technique in tilt-table testing: [8]

  • Dress patient in hospital gown without restrictive binding around abdomen or legs.

  • Insert an intravenous catheter and start a maintenance IV fluid drip with 0.9% NaCl.

  • Place patient supine on tilt table and secure patient with protective straps to avoid falls.

  • Apply blood pressure, heart rate, oxygen saturation, and rhythm monitors and record baseline measurements.

  • Have the patient rest supine for 10 minutes.

  • Provide a room that is quiet, dim, and a comfortable temperature.

  • Raise tilt table up to 80°.

  • Record blood pressure, heart rate, and oxygen saturations every minute.

  • Tilt table upright for 20-45 minutes depending on protocol.

  • Record rhythm changes on ECG strip.

  • Decide if pharmacologic provocation with nitroglycerine after 5 minutes of tilt or isoproterenol after 20 minutes of tilt is needed to provoke a response.

  • Record any symptoms or signs observed.

  • Terminate tilt if systolic blood pressure falls below 70 mmHg, even if symptoms are not present.

  • Terminate tilt if patient faints, and return patient to supine position.

  • Place patient in reverse Trendelenburg position if blood pressure does not normalize.

  • Administer a 250-mL bolus of 0.9% NaCl for hypotension.

  • Record blood pressure and heart rate until back to baseline.

  • Disconnect patient and allow patient to sit in chair for 5 minutes.

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Test Results

If provocative pharmaceuticals such as isoproterenol or nitroglycerine are used, differentiate the expected pharmacological effects of the drug from an abnormal response.

If avoidance of pharmacologic testing is desired, such as in a patient with ischemic heart disease, proceed with an upright tilt for 45 minutes. If a fainting response does not occur, the test is negative.

A positive tilt-table test result may be described as mixed, cardio inhibitory, or vasodepressor (see Overview). [9]

Classification of positive responses to tilt testing

One particular problem with tilt-table testing is the plethora of protocols with differing sensitivity, which can make reproduction of results unreliable. The reliability and accuracy of tilt-table studies is improved when combined with hemodynamic and volume measurements. [10] These procedures include nuclear hemodynamic studies, which can be performed in conjunction with an outpatient tilt-table test. They can be repeated at follow-up visits to assess response to treatment. Autonomic reflex testing, which includes the combination of vascular reactivity measures with the tilt-table test, can also be performed to improve the sensitivity of tilt-table testing. [10] However, a criterion standard for positivity remains to be. Adherence to positivity criteria is essential (see Table 2). If hemodynamic changes occur without syncope, the test is a false positive. [7]

Table 1. Classification of Positive Responses to Tilt Testing [9] (Open Table in a new window)

Type 1 -

Mixed

Heart rate falls at the time of syncope, but the ventricular rate does not fall to less than 40 beats/min-1 or falls to less 40 beats/min-1 for less than 10 s with or without asystole of less than 3 s. Blood pressure falls before the heart rate falls.

Type 2 -

Cardioinhibitory

A) Cardioinhibition without asystole: heart rate falls to a ventricular rate less than 40 beats/min-1 for more than 10 s, but asystole of more than 3 s does not occur before the heart rate falls.

B) Cardioinhibition with asystole: Asystole occurs for more than 3 s. Blood pressure falls with or occur before the heart rate fall.

Type 3 -

Vasodepressor

Heart rate does not fall more than 10% from its peak at the time of syncope.

 

Exception 1. Chronotropic incompetence: No heart rate rise during the tilt testing (ie, less than 10% from the pre-tilt rate).

 

Exception 2. Excessive heart rate rise: An excessive heart rate both at the onset of the position and throughout its duration before syncope (ie, greater than 130 beats/min-1).

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Definitions of Key Terms

Dysautonomias, primary

Deficiency of mechanisms that increase α- and β- adrenergic tone as a result of baroreceptor stimulation to compensate for a decrease of venous blood return to the heart

HUT

Abbreviation for head-up tilt test

Neurally mediated hypotension

Reduction in systolic blood pressure 25 mmHg from baseline supine values, sustained for at least 1 minute, with no associated increase in heart rate, and accompanied by symptoms of presyncope

Neurocardiogenic syncope

Acute hypotension with or without bradycardia

Orthostatic (postural) hypotension

Greater than 20-30 mmHg drop in systolic blood pressure plus a greater than 10 mmHg drop in diastolic blood pressure: Orthostatic hypotension is a common cause of a temporary loss of consciousness or feelings of lightheadedness, which results from changing body position from a supine or sitting position to a more vertical or upright position. Normally, blood tends to pool in the lower extremities due to gravity whenever a person stands up, potentially reducing the amount of blood available to return to the heart or brain.

The sympathetic nervous system regulates blood vessel tone by modulating nerve traffic to lower extremity blood vessels. The arterial and venous circulations compensate for pooling by constricting; thus redirecting blood flow from the leg veins back toward the heart. However, poor sympathetic tone to the lower extremity blood vessels can cause the mechanisms of arterial and venous constriction to fail, resulting in a disproportionate pooling of blood in the legs, instead of returning blood to the circulation, resulting in less oxygen supplied to the brain and heart. As a result, a person feels lightheaded and may even faint.

Postural orthostatic tachycardia syndrome (POTS)

The occurrence of orthostatic symptoms in association with either a 30 beats/ minute increase in heart rate from baseline within 10 minutes of being tilted upright, sustained for 1 minute or more, or a heart rate of higher than 120 beats/ minute in the same period

Presyncope

The presence of premonitory symptoms and signs of imminent syncope such as severe weakness, lightheadedness, nausea, or diaphoresis

Syncope

Pan-cerebral hypoperfusion accompanied by a lack of postural tone and unconsciousness without focal neurological deficit

Vasodepressor syncope

Abrupt drop in blood pressure with symptoms

Vasovagal syncope

Abrupt drop in blood pressure and heart rate with symptoms: The hallmark of vasovagal syncope is the occurrence of one to several symptoms either before, during, and immediately after a brief loss of consciousness. Symptoms are varied, and may include nausea, flushing, headache, vertigo, palpitations, and asthenia. [11]

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