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Vagus nerve stimulation induces changes in respiratory sinus arrhythmia of epileptic children during sleep
Boubker Zaaimi1, Reinhard Grebe, Patrick Berquin
1GRAMFC, Faculté de Médecine, Amiens, France.
Insights
Vagus nerve stimulation (VNS) in children with epilepsy can disrupt the synchronization between heart rate and breathing, potentially impairing oxygen delivery. This effect on respiratory sinus arrhythmia (RSA) warrants careful consideration in clinical practice.
Area of Science:
- Pediatric Neurology
- Autonomic Nervous System Research
- Epilepsy Treatment
Background:
- Pharmacoresistant epilepsy in children often involves autonomic nervous system (ANS) dysfunction.
- Vagus nerve stimulation (VNS) is a treatment for epilepsy, but its effects on cardiorespiratory interactions require further investigation.
Purpose of the Study:
- To analyze the short-term impact of VNS on respiratory sinus arrhythmia (RSA) in children with drug-resistant epilepsy.
- To assess how VNS affects the synchronization between cardiac and respiratory activity.
Main Methods:
- Evaluated RSA magnitude (heart rate variability relative to respiration) using polysomnography in 10 children undergoing VNS.
- Measured electrocardiography (ECG), electroencephalography (EEG), respiratory parameters, and VNS artifacts before, during, and after VNS.
Main Results:
- VNS altered respiratory frequency and amplitude, with variable effects on cardiac activity.
- RSA magnitude significantly decreased in 60% of children during VNS, indicating disturbed heart rate-respiration coupling.
- Changes in cardiorespiratory parameters were observed but not consistently correlated with RSA magnitude changes.
Conclusions:
- VNS modifies cardiac-respiratory synchronization, potentially reducing oxygen delivery to tissues.
- This effect, combined with existing ANS dysfunction in epilepsy patients, could be life-threatening.
- Changes in respiratory parameters during VNS may serve as markers for treatment effectiveness.
Purpose:
This study analyzed the direct short-term effect of vagus nerve stimulation (VNS) on respiratory sinus arrhythmia (RSA) in children with pharmacoresistant epilepsy.
Methods:
RSA magnitude is calculated as the ratio between maximum and minimum heart rate for each respiratory cycle-before, during, and after the actual VNS period. In 10 children, changes in RSA magnitude were evaluated on polysomnographic recordings, including electrocardiography (ECG), electroencephalography (EEG), thoracoabdominal distension, nasal airflow, and VNS artifacts. Measurements during stimulation were compared with those at baseline, immediately preceding the VNS periods and individually for each patient.
Result:
During VNS, respiratory frequency increased and respiratory amplitude decreased with a variable effect on cardiac activity. The coupling between heart rate and respiratory rate was disturbed and RSA magnitude decreased significantly in 6 of 10 children during VNS. These changes in RSA magnitude varied from one child to another. The observed changes for respiratory and cardiac activity were concomitant with changes in RSA but were not correlated.
Conclusion:
Together with disorders of respiration, cardiac activity, and oxygen saturation (SaO(2)) described previously. VNS also modifies synchronization between cardiac and respiratory activity, resulting in poor optimization of oxygen delivery to tissues that can be regarded as an additive side effect, which should be considered in patients with already altered brain function. This interaction between the effects of VNS and potential autonomic nervous system (ANS) dysfunction already reported in epileptic patients should be considered to be potentially life-threatening. In addition, evaluation of changes in respiratory parameters can also provide reliable markers for further evaluation of the effectiveness of VNS.
