[Role of @entity855 ( @entity855 ) in head-up tilt-induced XXXX ].

@entity1 @entity859 @entity907 @entity1163 @entity299 @entity3044 @entity855
INTRODUCTION AND OBJECTIVES: Recent studies have demonstrated that @entity859 is an endogenous modulator of the @entity299 , and could provoke a vasovagal response during head-up tilt test. @entity3044 has been the drug of choice to increase the sensitivity of this testing. The aim of the present study was to analyze the role of @entity859 in head-up tilt-induced @entity1163 in susceptible @entity1 , and to compare the relative sensitivities of @entity859 and @entity3044 . METHODS: Thirty @entity1 with unexplained @entity1163 (16 female and 14 male, mean age 37.1 +/- 18 years), no @entity299 and negative baseline head-up tilt test were studied. After the baseline test, @entity1 were randomized to receive @entity855 (bolus injections of 3, 6 and 9 mg/ 5 min) or @entity3044 (bolus injections of 2, 4 and 6 micrograms/5 min) and underwent a second tilt test. After 15 min at rest, @entity1 received the alternative drug and a third test was performed. Eleven normal control subjects were tested with @entity859 in the upright position to determine its effects. RESULTS: A vasovagal response was induced in 7 @entity1 (23.3%) after @entity855 administration. Nine @entity1 (30%) showed a positive response with @entity3044 . Only 2 @entity1 (6.6%) showed a positive response with both drugs. Of the control subjects, one (9%) had a vasovagal response after @entity855 administration. CONCLUSIONS: We conclude that @entity855 seems to be a useful tool to provoke @entity907 in susceptible @entity1 during head-up tilt test.
