Tilt Table Study
A tilt table test is administered to diagnose the cause of fainting (neurocardiogenic syncope). Typically, it is only administered to patients who have had several unexplained episodes of fainting. In some cases, however, the test is given to a patient who has had only one episode, but it is believed that another episode would put the patient at great risk of injury because of advanced age, other medical conditions or work environment.
Some patients with syncope have symptoms that warn them that they are about to faint, such as pallor, lightheadedness, weakness, nausea, sweating, irregular heartbeats or blurred vision. Fainting may be a response to a particular trigger such as emotional trauma or the sight of blood, but it can also occur in the absence of any such trigger.
Reasons for a Tilt Table Test
Tilt table tests are recommended when there is a suspicion that neurocardiogenic syncope is the cause of fainting, and the diagnosis requires confirmation. Neurocardiogenic syncope occurs when the nervous system alters the heart rate, temporarily lowering the patient's blood pressure. The diminished flow of blood to the brain results in fainting. The tilt table test attempts to replicate the fainting experience for diagnostic purposes.
Tilt Table Test Procedure
The tilt table test is a simple one, performed with the patient lying flat on a special table in the doctor's office. During the test, the patient is strapped in place to the table, while blood pressure and heart rate are constantly monitored by an electrocardiogram (EKG) machine and blood pressure cuff. The table is tilted until the patient is in an upright position, simulating the change of position experienced when a patient stands up from a lying or sitting position. The equipment that has been put in place provides data for evaluation of the body's cardiovascular response to this change of position. In addition to the EKG electrodes and a blood pressure cuff, the patient may have an intravenous (IV) line inserted for medication delivery.
If a patient does not have a fainting episode when moved into an upright position, she or he may be kept in that position for up to 45 minutes. If there are still no symptoms, a medication called isoproterenol may be administered through the IV line. This medication lowers diastolic blood pressure and increases heart rate, potentially precipitating syncope. When a patient experiences signs that he or she is about to faint, or actually loses consciousness, the table is returned to its horizontal position immediately. Once the tilt table test has been completed, a patient can promptly return to normal activities.
Risks of a Tilt Table Test
The tilt table test is considered very safe, but, as with any medical procedure, complications are possible. A few patients may experience prolonged blood pressure or a longer-than-normal pause between heartbeats (asystole). In almost all cases, these complications are resolved once the table is returned to its original position and the patient is lying down.