Unexplained syncope: diagnostic value of tilt-table testing.

Vasovagal syncope is a common syncope in patients who have no structural heart disease and occurs more often in young adults. It typically occurs in the erect posture, either standing or sitting. Upon recognition of the prodrome associated with NCS, subjects may avert syncope by lying down or putting the head between the knees. Use of head-up tilting is a recognized diagnostic tool and widely used for the evaluation of vasovagal syncope. However, cardiac diagnostic tests are not 100% accurate. This fact was recently underscored by what occurred in the recent tragic loss, due to ventricular fibrillation, of basketball star Reggie Lewis of the Boston Celtics. It is alleged that the tilt-table test was positive but that he also had structural heart disease. The most important diagnostic tool is the physician's clinical judgment.