A tilt table test is used to evaluate the cause of unexplained fainting.

Your doctor might recommend a tilt table test if you have repeated, unexplained episodes of lightheadedness, dizziness or fainting. The test can help determine if the cause is related to your heart rate or blood pressure.

Your doctor might recommend a tilt table test to try to trigger your signs and symptoms — lightheadedness, dizziness or fainting — while your heart rate and blood pressure are being monitored.

Your nervous system controls your heart rate and blood pressure. It may suddenly lower your heart rate and blood pressure for a short time when you're moved to an upright position during the tilt table test. As a result, less blood flows to your brain, possibly causing you to faint.

A tilt table test is generally safe, and complications are rare. But, as with any medical procedure, it does carry some risk.

Potential complications include:

• Nausea and vomiting after fainting
• Weakness that can last several hours
• Prolonged low blood pressure after the test

These complications usually go away when the table is returned to a horizontal position.

You might be asked not to eat or drink for two hours or more before a tilt table test. You can take your medications as usual, unless your doctor tells you otherwise.

To prepare you for the test, a member of your health care team will:

• Have you lie flat on a table that has a footboard and place straps around you to hold you in place.
• Place sticky patches (electrodes) on your chest, legs and arms. Wires connect the electrodes to an electrocardiogram machine that monitors your heart rate.
• Place a blood pressure monitor or cuff on your finger, on your arm or on both to check your blood pressure during the test.
• Place an IV line into a vein in your arm for delivering medication, if needed.

During a tilt table test

• You'll start by lying flat on your back on the motorized table for about five minutes.
• You'll be moved to a nearly vertical position, where you'll remain from five to 45 minutes, depending on the reason for the test. While vertical, you'll be asked to remain as still as possible but to report signs and symptoms such as nausea, sweating, lightheadedness or irregular heartbeats.
• If you don't faint or have other symptoms after 45 minutes, you might receive the medication isoproterenol (Isuprel) through an IV line in your arm. The medication might prompt the abnormal nervous system reflex that causes you to faint.
• You then remain in the upright position for another 15 to 20 minutes.

Your heart rate and blood pressure will be monitored in each position to evaluate your body's cardiovascular response to the change in position.

After a tilt table test

If you faint while vertical, the table will be returned to a horizontal position immediately and you'll be monitored. Most people regain consciousness almost immediately.

In some cases, if blood pressure and heart rate changes indicate you are about to faint, the table is returned to a horizontal position so that you don't lose consciousness.

When the test is complete, you can return to your normal activities.

The results of a tilt table test are based on whether you faint during the test and what happens to your blood pressure and heart rate.

The result is positive if your blood pressure decreases and you feel dizziness or faint during the test.

The result is negative if your heart rate increases only slightly, your blood pressure doesn't drop significantly, and you don't have signs or symptoms of fainting.

Depending on the results, your doctor might recommend additional tests to exclude other causes of fainting.