Maria Stella Fera, Alessandro
Carunchio, Andrea Mazza, Maurizio Burattini, Maria Margherita Martinelli, Vincenzo Ceci.
Division of Cardiology, S. Spirito Hospital, Rome, Italy
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Syncope is defined as a sudden temporary loss of
consciousness associated with a deficit of postural tone with vasodepression, bradycardia
and with spontaneous recovery. The common end result of these phenomena is diffuse
cerebral ischemia. Neurally mediated (or vasovagal) syncope can be induced by head-up tilt
testing in up to 80% of patients with unexplained syncope, in the absence of structural
heart disease1. It is believed that tilt induced
vasovagal syncope results from the activation of ventricular mechanoreceptors, during
vigorous contraction, in the presence of an underfilled ventricle2.
A variety of therapeutic measures have been introduced in treating this type of syncope
(betablockers, disopyramide, cafedrine, domperidone, dihydroergotamine, ethylephrine,
scopolamine, clonidine, theophylline, fluoxetine, sertraline, serotonin re-uptake
inhibitors, salt supplement, implantation of a permanent pacemaker), with unclear results.
The natural history of the syndrome seems to have, in itself, a favourable medium-term
prognosis with syncopal recurrences in 20% of the patients per year. Recent studies have
reported benefit from empiric medical therapy or guided by repeated head-up tilt testing,
in all patients with neurally mediated syncope, however, the incidence of syncope
recurrence in medically untreated patients is low. Grubb et al3
have demonstrated that the absence of syncope during repeat head-upright tilt table
testing after the initiation of therapy (in patients with an initial positive response)
appears to predict the absence of symptom recurrence over the long-term. Fitzpatrick et al1, Sheldon et al4 have
demonstrated an 80-95% symptomatic reproducibility of tilt table testing in patients with
recurring syncope. The method of tilt guided therapy has been questioned by Brignole et al5 in a study of 30 patients with syncope: the response to
therapy was similar in both treated and untreated (placebo) patients. Fitzpatrick et al6 have reported that the incidence of syncope decreases,
in the first year, regardless of treatment. The high degree of variability in recurrence
rates makes evaluation of various therapeutic modalities difficult. The aim of the present
study was to assess in patients with unexplained syncope: 1. the diagnostic value of basal
and potentiated with nitrates head-up tilt test; 2. the efficacy of the prophylactic
treatment guided by serial head-up tilt test.
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