Syncope is both one of the most common and one of the most challenging problems seen in medical practice. In spite of intensive medical evaluation, the cause of syncope remains unknown in a significant number of patients. In recent years, head-up tilt test has been of increasing interest as a diagnostic aids in patients with unexplained syncope. This study investigated the clinical utility of this technique in te evaluation of patients with vasovagal syncope.

Seven patients with unexplained syncope were evaluated with a 60 degree or 80 degree head-up tilt test with or without intravenous infusion of isoproterenol(1-4ug/min) in an attempt to provoke bradycardia, hypotension or both. There were 4 males and 3 females with a mean age of 35±8 years.

1) During head-up tilt test, vasovagal responses were provoked in 5 of 7 patients(71.4%) with syncope of unknown origin. During the test, there was no complication associated with the test.

2) During tilt-induced vasovagal reponse, mean systolic blood pressure decreased to 84±12mmHg from supine control of 125±21mmHg(p<0.01) and mean diastolic blood pressure decreased to 50±17mmHG from supine control of 76±14mmHg(p<0.01).

3) Five patients with positive results of the tests were followed up for 12months and they had a good outcome free of recurrence.

Head-up tilt test appeared safely applicable test in patients with suspected vasovagal syncope and good prognosis was expected in the patients.