See also

Afebrile Seizures
Supraventricular Tachycardia
Altered conscious state
Basic Paediatric ECG interpretation

Key Points

1. An arrhythmia should be considered in all children with syncope
2. Most paediatric syncope is vasovagal
3. A thorough history is the best strategy to determine the cause of  syncope and guide further investigation

Background

• Syncope is a brief and sudden loss of consciousness associated with loss of postural tone with spontaneous recovery
• Paediatric syncope is common, with about 15% of children experiencing an episode before the end of adolescence
• Most paediatric syncope is benign and has an autonomic cause ie vasovagal or orthostatic
• Syncope is less commonly caused by life-threatening cardiac conditions such as structural abnormalities and arrhythmias
• Neurological conditions such as seizure and migraine may mimic syncope

Causes

Autonomic

• Reflex syncope
• Eg vasovagal syncope
• Clear precipitating event, eg tiredness, hunger, heat, dehydration, emotion
• Orthostatic hypotension
• Within 2-3 minutes of assuming an upright position:
  • decrease in systolic blood pressure >20 mmHg
    or 
  • decrease in diastolic blood pressure of >10 mmHg
• Causes include hypovolaemia, anaemia, electrolyte abnormalities, menorrhagia, medications

• Postural orthostatic tachycardia syndrome (POTS) 

• Daily symptoms of chronic orthostatic intolerance
  and
• Within 5-10 minutes of assuming an upright position:
• HR increase >40 bpm
  or
• HR increase >30 bpm without postural hypotension

• Breath-holding spells 

Cardiac

• Brady/tachyarrhythmia
• Long QT syndrome
• Brugada syndrome
• Catecholaminergic polymorphic ventricular tachycardia
• Conduction disease eg Wolff-Parkinson-White syndrome
• Structural abnormalities eg congenital heart disease, cardiomyopathies, myocarditis

Differential diagnoses

• Seizure
• Migraine
• Hypoglycaemia
• Toxin exposure eg carbon monoxide, clonidine
• Functional disorder
• Narcolepsy

Assessment

History

The child’s medical history and description of the event, including any previous episodes, is essential in identifying the cause of syncope

Key features to differentiate syncope from a seizure

Examination

• Orthostatic heart rate and blood pressure measurements
• Complete cardiac and neurological examination

Management

Investigations

• ECG should be obtained in all children at least once. May not be required if done previously and there is no additional concern (see ECG interpretation)
• BGL can be useful if the child is seen shortly after the event
• FBE (if anaemia is suspected)
• Consider pregnancy testing

Treatment

Children with frequent and/or problematic vasovagal or orthostatic syncope

• Avoid usual triggers
• Increase fluid and salt intake
• Early recognition of prodromal symptoms

Consider consultation with a local paediatric team when

• Suspicion of cardiac syncope on history, examination or ECG. Urgently refer to a paediatrician or cardiologist
• Children with recurrent vasovagal or orthostatic syncope that do not respond to non-pharmacological treatment. Refer to paediatrician or cardiologist
• Children with presentations suspicious for seizures. Refer to paediatrician or neurologist

Consider transfer when

• Children are persistently symptomatic on assessment
• Children with clustering of syncope with cardiac features
• Requiring care beyond the level of comfort of the local hospital

For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services

Consider discharge when

The most likely cause of syncope has been identified and follow up has been arranged

Last updated November 2023