Neurally mediated syncope: Is it really an endothelial dysfunction?

OBJECTIVE: Syncope is a common problem in children and adolescents. Neurally mediated syncope is the most frequent form of this disorder. Although several studies have evaluated the pathophysiology of neurally mediated syncope, it is still not completely understood. METHODS: We performed a cross-sectional study that included 27 patients aged 5–20 years with unexplained syncope and 30 healthy subjects as a control group. All subjects in both groups were assessed for endothelial function by investigating the following physical and chemical factors: flow-mediated dilation (FMD), intima-media thickness (IMT), circulating vascular cell adhesion molecule (VCAM), intercellular adhesion molecule (ICAM)], and endothelial leucocyte adhesion molecule (E-selectin), as well as epinephrine and norepinephrine. The data were statistically analyzed utilizing the SPSS 20. Significant differences between the groups in terms of mean scores were assessed using an independent sample t-test. RESULTS: Mean FMD was significantly higher in the syncope case group than in the control group (p=0.028). There was no significant difference in IMT between the two groups; however, mean levels of ICAM (p=0.02) and VCAM (p=0.008) were significantly higher in the case group than in the control group. The levels of E-selectin also increased in the case group, but not to a statistically significant extent. The mean levels of epinephrine (p=0.01) were significantly lower in the case group than in the control group, and the level of norepinephrine serum decreased slightly, but not significantly, in the syncope patients. CONCLUSION: Our results showed that an endothelial dysfunction or augmented endothelial function might exist in patients with neurally mediated syncope.