What is a Tilt Table Test?

The symptoms of lightheadedness or faintness are very common and they are a major reason for physician visits, especially visits to a neurologist. Lightheadedness can be caused by a number of diseases and disorders—identifying the particular disease can be difficult if the physician does not witness an episode firsthand. Despite being a very common symptom, lightheadedness rarely seems to occur during the office visit. Since witnessing an episode of faintness is often critical for diagnosis, doctors have devised the tilt table test to attempt to evoke a fainting spell in a controlled environment.  Physicians refer to lightheadedness or feeling faint as presyncope while the term syncope refers to actually “passing out,” “falling out,” or otherwise spontaneously losing consciousness.

 

 

A tilt table test is much as it sounds, the patient lies down on a special table, a tilt table, which can be moved remotely by the examiner. The patient is secured to the tilt table to prevent injury and the table is moved from horizontal to vertical at varying rates of speed or held in place with the body at a 70 degree angle with respect to the floor. During the tilt table test, the patient’s vital signs are recorded, including heart rhythm and blood pressure. Depending on the tilt table test protocol, blood pressure may be measured by a pressure transducer placed directly into an artery. Medications may be administered during the test, such as isoproterenol. During the tilt table test, the patient is usually asked to report lightheadness or if they are about to lose consciousness.

 

Because there is motion and provocative medications administered during the tilt table test, patients are asked to not eat for about eight hours prior to the exam. The tilt table test usually lasts about two hours. For blood pressure recordings, a needle may be placed into the artery, which can be slightly painful.

 

The tilt table test is a fairly good way of differentiating between vasovagal and cardiogenic syncope. To understand vasovagal syncope, it is important to first realize that the brain needs a constant uninterrupted flow of blood. When we rise from a seated or lying position, our brains must sense the change of position, instruct the blood vessels in our legs to squeeze, and send additional blood to the brain. Otherwise, gravity will pull all of the blood to our feet leaving the brain starved of blood. Vasovagal syncope or fainting is caused when the body’s normal reaction to a change in posture is dysfunctional and the tilt table test can challenge this system. Disruptions in this body system are apparent in the various monitoring devices used in the tilt table test.

Cardiogenic presyncope or syncope is lightheadedness or losing consciousness due to a problem with the heart. The heart problem is often caused by an abnormality in the heart’s electrical system called a cardiac arrhythmia. The tilt table test may not be lead to a diagnosis of this form of syncope but may suggest it if the tilt table test is negative. An accurate diagnosis of cardiogenic syncope may require the patient to wear a Holter monitor which constantly monitors heart rhythm over 24 hours.