BACKGROUND Tilt testing is used to establish the diagnosis of neurally mediated syncope. However, applicability of the tilt test is limited by test sensitivity and length of time required to perform the test. We hypothesized that adenosine could facilitate the induction of neurally mediated syncope through its sympathomimetic effects and therefore could be used as an alternative to routine tilt...

To test the hypothesis that systemic inhibition of nitric oxide (NO) synthase does not alter the regulation of sympathetic outflow during head-up tilt in humans, in eight healthy subjects NO synthase was blocked by intravenous infusion of NG-monomethyl-L-arginine (L-NMMA). Blood pressure, heart rate, cardiac output, total peripheral resistance (TPR), and muscle sympathetic nerve activity (MSNA)...

BACKGROUND In patients with vasovagal syndrome, head-up tilt testing may reproduce symptoms generally associated with vasodepression. Recent research suggests ATP testing identifies patients with abnormal vagal cardiac inhibition. This preliminary study examined the joint contribution of both tests in identifying underlying mechanisms in the general population with vasovagal syndrome. METHODS...

We assessed the cerebral blood flow velocity response to head-up tilt test in patients with typical neurocardiogenic syncope compared with patients showing postural tachycardia. Fifty patients (21 men) with history of orthostatic intolerance, younger than 50 years (mean 27 +/- 10), participated in the study. Transcranial Doppler sonography of the middle cerebral artery, heart rate and brachial ...

Fifteen patients aged 10 to 18 years with syncope of unknown origin, and 10 healthy control children aged 11 to 18 years, were evaluated by head-up tilt to 60 degrees for 60 minutes. Six patients (43%) reproduced symptoms of syncope during the examination. Four had a typical vasovagal reaction; two had marked hyperventilation. None of the children in the control group had syncope. The head-up t...

1997; 77: 273–5. [32] Natale A, Beheiry S, Wase A et al. Occurrence of clinical asystole in patients without evidence of structural heart disease: response to tilt test and follow-up. Circulation 1999; 100: I-245. [33] Fitzpatrick A, Sutton R. Tilting towards a diagnosis in recurrent unexplained syncope. Lancet 1989; 1: 658–60. [34] Strasberg B, Rechavia E, Sagie A et al. The head-up tilt table...

BACKGROUND This randomized study was aimed to compare the diagnostic value of two head-up tilt testing protocols using sublingual nitroglycerin for provocation in patients with recurrent unexplained syncope and normal heart. METHODS The patients with normal findings in physical examination, electrocardiography and echocardiography were randomly submitted to one of upright tilt test protocols....