European Heart Journal Advance Access originally published online on March 12, 2008
European Heart Journal 2008 29(8):1075; doi:10.1093/eurheartj/ehn095
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Tilt testing potentiated with sublingual nitroglycerin in children with unexplained syncope: reply
Department of Cardiology
Ospedale Valduce
Via Dante, 11
22100 Como
Italy
Email: gfoglia{at}valduce.it
Department of Cardiology
Ospedale Umberto I
Mestre-Venezia
Italy
We really appreciate Dr Jastrzebska-Maj et al.'s interest in our work, dealing with the diagnostic management of children with unexplained syncope.1 Head-up tilt testing (HUT) potentiated with sublingual nitroglycerin (NTG) is an accepted examination in adults with unexplained syncope, but, so far, very few studies assessed the diagnostic value of this test in children.2,3
In our study, we evaluated a sublingual NTG–HUT protocol in children aged 5–17 years. We found a 63% positivity rate, similar to that reported in adults, and an 86% specificity, similar to the 91% reported by Dindar et al.2 On the contrary, Vlahos et al.3 found a lower 67% specificity. As stated by Dr Jastrzebska-Maj et al., these contrasting results may be because of differences in HUT protocols and different inclusion criteria in study populations. Indeed, some patients' characteristics, such as obesity and regular resistance training, may influence the HUT specificity. Moreover, also the utilization of intravenous cannulation may significantly affect the HUT specificity, especially in children.4 In order to reduce the influence of these factors, we did not utilize intravascular instrumentation and enrolled only sedentary children with normal weight for age.
Another important issue in the evaluation of HUT diagnostic value remains the high prevalence of neurally mediated syncope in children, which may influence HUT specificity. Indeed, a ‘false’ positive response in healthy control subjects might represent a true susceptibility to clinical neurally mediated syncope.4 Nevertheless, if we excluded our control subject, who had spontaneous syncope on follow-up, in our study, the HUT specificity would increase from 86 up to 89%. Thus, in our opinion, this potentially confounding variable may not really affect the diagnostic and clinical value of the test.
Finally, Dr Jastrzebska-Maj et al. question whether it is acceptable to utilize the same dose of sublingual NTG for both adults and children. However, the 86% specificity that we found also in younger children (aged 
8 years) may prove that the NTG–HUT outcome is not correlated to patients' body weight. Moreover, in our study, NTG was very well-tolerated in children, both in patients and in control subjects.
Thus, we believe that utilizing a fixed spray dose of sublingual NTG allows us to perform a simple and well-accepted test also in children.
References
- Foglia-Manzillo G, Giada F, Fteita N, Nessi I, Santarone M, Raviele A. Tilt testing potentiated with sublingual nitroglicerine in children with unexplained sincope. Eur Heart J (2007) 28:2605–2609.
[Abstract/Free Full Text] - Dindar A, Cetin B, Ertrugul T, Cantez T. Sublingual isosorbide dinitrate-stimulated tilt test for diagnosis of vasovagal syncope in children and adolescents. Pediatr Cardiol (2003) 24:270–273.[CrossRef][Web of Science][Medline]
- Vlahos AP, Tzoufi M, Katsouras CS, Barka T, Sionti I, Michalis LK, Siamopolou A, Koletis TM. Provocation of neurocardiogenic syncope during head-up tilt testing in children: comparison between isoproterenol and nitroglycerin. Pediatrics (2007) 119:e419–e425.
[Abstract/Free Full Text] - Lewis DA, Zlotocha J, Henke L, Dhala A. Specificity of head-up tilt testing in adolescents: effect of various degrees of tilt challenge in normal control subjects. J Am Coll Cardiol (1997) 30:1057–1060.[Abstract]
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