Tilt Table Test

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Tilt table test

Definition

Tilt table testing is a medical test designed to study how the human heart adapts to changes in position.

Purpose

The American College of Cardiology considers the use of head-up tilt table testing to be the best means of evaluating symptoms and potential treatment for vasovagal syncope . More than 7 million Americans suffer from common fainting spells, but only recently has this standardized method been used to determine the root cause of these episodes. Syncope accounts for about 3% of all emergency room visits and nearly 6% of hospital admissions. Overall, it is believed that 6 million Americans are affected, and that vasovagal fainting (common fainting) is the most common type of syncope.

Syncope can be described as a pathological brief loss of consciousness caused by a temporary deficiency of oxygen in the brain . It is called by many other names, including:

neurally-mediated hypotension
fainting reflex
neurocardiogenic syncope
vasodepressor syncope
vasovagal reflex
autonomic dysfunction

The autonomic nervous system normally compensates for the fact that blood pools in the legs when a person suddenly stands up, decreasing the volume of blood available to the heart and eventually the brain. Communication between the brain and the rest of the body causes a rush of adrenaline to be sent into the bloodstream. This speeds up the heart rate and causes the blood to be pumped rapidly and efficiently to necessary areas, especially the heart and brain. When the necessary communication from the brain does not occur or is not received, the person feels light-headed or faint and may actually faint. This is basically what happens when someone gets out of bed or a hot tub too fast. When this occurs, it can often lead to difficulty in functioning and to injuries.

Tilt table testing is designed to study the human body's heart rate and blood pressure adaptations to changes in position. To perform the test, patients lie on their back on a table, which is then tilted to a 60° angle, and then an 80° angle. This positioning is an attempt to bring on an episode of fainting to determine whether the fainting spells are common or malignant. Malignant syncope, possibly caused by a heart arrhythmia or flutter, cannot be reproduced by a tilt table test.

The application of the tilt test as a diagnostic tool in the United States has doubled in the past decade. However, it is often not paid for by insurers, including Medicare .

Precautions

Precautions are few with the tilt table test, as the person is constantly monitored. However, when any drug is used with this test, the appropriate precautions for that particular drug should be observed. The physician should also be informed of any allergies to any sympathomimetic drugs, including several of the diet pills on the market, or of any serious heart-rhythm disorders, or that the person is not feeling well during the test.

Description

The tilt table test takes approximately one hour. Patients lie on their backs and are secured to the table by three straps, under the arm and across the abdomen, across the pelvis, and across the knees. While the person is in a prone position, blood pressure and pulse are taken and electrodes are put in place to monitor the heart. An intravenous line is started in order to provide fluids as necessary during the test. Special electrodes that measure the amount of oxygen going to the brain are placed on the forehead. The head of the table is then tipped upward to a maximum of 75° angle while heart rhythm, pulse, blood pressure, and oxygen saturation at the brain are continuously monitored. Isoproterenol, or Isuprel, a medication with similar properties to adrenaline, is often injected intravenously during the test to duplicate the normal reaction of the body.

Preparation

In order for a patient to make informed decisions about any diagnostic test or procedure, detailed information and description of the test to be performed need to be provided. The patient should understand the purpose of the tilt table test and the diagnosis that the physician is trying to confirm or rule out.

Aftercare

After the procedure, the patient is asked to move from the supine position to a sitting position, and is observed for a short period of time. When ready, the individual transfers from the sitting position to standing. After additional observation and taking of vital signs , the individual is allowed to go home.

Complications

Complications as a result of a tilt table test are very infrequent, but could potentially include significant changes in blood pressure while in the supine position, and any adverse reactions to any drugs administered during the tilt table test.

KEY TERMS

Sympathomimetic —A drug that mimics the effects of stimulation of organs and structures by the sympathetic nervous system.

Syncope —A loss of consciousness over a short period of time, caused by a temporary lack of oxygen in the brain.

Results

Normal results of the tilt table test should help the physician in assessing what may or may not be the cause of the syncope. Abnormal results include any pathologic reactions to the position changes or sensitivity enhancing techniques such as the administration of isoproterenol or other related drugs.

Health care team roles

In most cases, a licensed physician will be in charge of conducting a tilt table test; the physician may be a cardiologist or neurologist. Both registered nurses (RNs) and licensed practical nurses (LPNs) may assist the patient in understanding and preparing for the test, and monitor vital signs during the test. An RN may start the intravenous infusion, or attach and monitor electrocardiogram leads and oxygenation-measuring equipment.