Autonomic nervous system functions in children with breath-holding spells and effects of iron deficiency

To analyse the activity of the autonomic nervous system during breath-holding spells, we assessed the ECG changes, including ventricular repolarization parameters before and during the spell. We also analysed the effects of iron deficiency on these ECG parameters.

The study group consisted of 37 children with breath-holding spells (30 cyanotic, 7 pallid) (mean age+/-SD: 12.9+/-10.8 mo). Twenty-six healthy children (mean age+/-SD: 14.4+/-8.6 mo) served as a control group. All patients and controls had standard 12-lead simultaneous surface ECG. All patients had ECG recordings during at least one severe breath-holding spell obtained by "event recorder". Traces obtained by "event recorder" were analysed in terms of mean heart rate and the frequency and duration of asystole during the spell.

Respiratory sinus arrhythmia on standard ECGs and asystole frequency during spells were higher in patients with pallid breath-holding spells. Patients with iron deficiency had a lower frequency of respiratory sinus arrhythmia and prolonged asystole time during the spell. There was no difference in terms of ventricular repolarization parameters (QT/QTc intervals and QT/QTc dispersions) between patients and controls and between patient subgroups (cyanotic versus pallid).

These results confirmed the presence of autonomic dysregulation in children with breath-holding spells. Iron deficiency may have an impact on this autonomic dysregulation. Ventricular repolarization was unaffected in patients with breath-holding spells.