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Updated: Aug 20, 2026

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus
Published on: April 5, 2011
Circadian variation of QTc dispersion in children with vasovagal syncope
Serdar Kula1, Rana Olgunturk, F Sedef Tunaoglu
1Department of Pediatric Cardiology, Medical Faculty, Gazi Hospital, Gazi University, 06500 Beşevler, Ankara, Turkey. pedcar@gazi.edu.tr
Aims:
To assess the validity of QTc dispersion to cardiac autonomic nervous function status.
Method And Results:
Prospective comparisons of QTc dispersion measurements in 77 neurally mediated cardiac syncope (NMCS) patients (29 boys, 48 girls, mean age 13.4+/-0.78) were evaluated. Head-up tilt test (HUT) was positive in 38 patients and negative in 39 patients. QTc dispersion was significantly higher early morning and late night in HUT-positive group compared with HUT-negative group (p<0.001). Although there was a circadian rhythm in HUT-positive group, there was no change on the QTc dispersion within a day in the HUT-negative group. QTc dispersion in the HUT-positive group was high in accordance with their high sympathetic nervous stimulation. Moreover, QTc dispersion was higher during late night and early morning than the rest of the day.
Conclusion:
These results may explain why the HUT-positive patients usually have their syncope attacks early in the morning. Additionally, we can use QTc dispersion measurement as a new noninvasive electrocardiographic test to evaluate cardiac sympathetic nervous system in NMCS.
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