SYNCOPE AND A TILT-TABLE TEST
There are many causes of fainting, losing consciousness or having lightheaded spells. In most cases, the situation can be diagnosed by a cardiac electrophysiologist. When people have syncope, i.e. a sudden loss of consciousness, if they have a history of heart problems such as a previous heart attack or wear heart muscle (cardiomyopathy), there is a high suspicion that the cause of the syncope was rapid, dangerous rhythm disturbance called “ventricular tachycardia.”
This determined further by an EP (electrophsiologic) study.
Most people who have syncope, however, have no cardiac history and have normal hearts. The most common cause of their syncope is called “neurocardiogenic” or “vasovagal” syncope. This problem in itself is not dangerous. The only danger lies in a situation, i.e. in the wrong place and wrong time. The best test to determine if this is the cause of syncope is called a tilt-table test.
When one experiences neurocardiogenic syncope, we believe that the following is the body’s response and so-called mechanism: When a person stands up or sits up, blood pools into the veins in the legs by gravity. In some people, the return of blood to the heart is slower than normal, and at the time the heart responds by pumping blood a little more forcefully. This is also a normal response, but in those who suffer from neurocardiogenic syncope, this response is exaggerated and the heart pumps a lot stronger. This triggers pressure receptors inside the heart which tell the brain that the pressure inside the heart is too high. This is, of course, a false message. The brain then overreacts, as well, and both opens up the arteries by withdrawing all of its adrenalin-type activity and tells the heart to slow its heart rate down, which is an outflow of the nervous system which slows and calms the body system. This, in turn, takes a normal blood pressure and drops it suddenly to a very low blood pressure. Not enough blood and oxygen gets to the brain, the patient faints, and when one falls to the ground blood returns to the heart and everything is restored.
Often before losing consciousness patients receive a warming that something may happen. This warning may last a few seconds or minutes. Typically people report feeling hot or sweaty, claustrophobic, short of breath, lightheaded, or nauseated. After passing out and coming to, the patient often feels unwell and tired for some time thereafter.
The tilt-table test tries to provoke the problem. Ideally one would have had an episode of syncope in front of a doctor; however, since that is not usually possible, we try to bring it on in front of us. The test is usually done in the morning, on an empty stomach. An intravenous line is inserted, a blood pressure cuff is applied, and heart rhythm is continuously monitored. The patient lies on a bed and is strapped to the bed for safety reasons. The bed is simply tilted to an almost upright position, i.e., 70 to 80° leaning back only slightly, and the patient stands there for up to 25 minutes. We do not have the patient swinging in various angels and upside down. After 15 minutes, if nothing occurs, usually for another ten minutes and we continue to monitor heart rate and blood pressure. Once the patient reports feeling faint and blood pressure drops, the test
will be terminated. The table is returned back to the lying position, and the patient feels better usually within a dew minutes. We sometimes do provoke loss of consciousness, which can be uncomfortable.
There is no risk involved in this test, i.e. no risk of anything more dangerous happening than the fainting itself. Because the patient is strapped to the table, there is not risk of injury/ this may, however, cause the same comfortable feeling as the patient experienced outside at home. In some situations, a repeat test on medication is advised to ensure that the syncope will not
Allow one hour for the test. You may leave after the test, but we advise that someone else drive you as you may feel unwell after the test. The results are known immediately and reported to you and whoever is with you immediately. We then contact your doctor within 24 hours. There are various medications to try for this problem. Not all are immediately successful and it does involve a trial-and-error basis. Please ask your doctor for any other questions.