Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Syncope, chest pain and sudden-death red flags
Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Collapse with cardiac instability
A child who is unresponsive, not breathing normally, has ongoing chest pain with shock, sustained tachyarrhythmia or bradyarrhythmia, or collapses during exercise may have cardiac arrest, myocarditis, outflow obstruction or inherited electrical disease.
Action: Call emergency services and start paediatric basic life support with an AED or defibrillator when pulseless. For a child with a pulse, use ABCDE, stop exercise, monitor ECG and saturation, obtain glucose and vascular access and involve senior paediatric and cardiology teams. Treat the documented rhythm and shock, obtain urgent ECG and echocardiography, and investigate myocarditis, pulmonary embolism, aortic disease or toxic exposure as the phenotype indicates.
Overview
Separate common benign paediatric fainting and chest-wall pain from structural or electrical cardiac disease, select proportionate testing, and protect children with exertional, ECG or family sudden-death warning features.
Syncope is transient loss of consciousness from global cerebral hypoperfusion with rapid onset, short duration and spontaneous complete recovery. The diagnostic task is to distinguish reflex, orthostatic and cardiac mechanisms from seizure, metabolic and psychogenic events.
Vasovagal physiology combines peripheral pooling with reflex vasodilatation and sometimes bradycardia. Standing, heat, pain, dehydration and emotion are typical triggers, while a recognisable prodrome permits the child to lie down before losing posture.
Orthostatic intolerance produces dizziness, visual change, palpitations or fainting after standing. Measure posture-related heart rate and blood pressure after adequate rest, interpret by paediatric criteria and review hydration, anaemia, medicines and deconditioning.
Arrhythmic syncope may result from long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, Brugada syndrome, pre-excitation, SVT, ventricular tachycardia or heart block. Trigger pattern and family history can be more revealing than a normal interval ECG.
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Paediatrics and child healthOriginal SBA
Exertional syncope action
A 13-year-old collapses without warning halfway through a swimming race and recovers within a minute. An uncle died suddenly at age 28. Examination is currently normal. What is the safest plan?
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.
NHS long QT syndromeNational inherited arrhythmia symptoms, diagnosis and treatment information.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem ·
Structural causes include hypertrophic cardiomyopathy, severe aortic stenosis, pulmonary hypertension, anomalous coronary arteries, myocarditis and repaired congenital disease. Exercise increases demand and can expose fixed output or coronary limitation.
Chest pain in children most often originates from chest-wall muscle, costochondral joints, cough, asthma, reflux or anxiety. A sharp brief pain at rest or reproducible tenderness is much less concerning than pressure consistently stopping exertion.
Myocarditis can follow or accompany viral symptoms and range from chest pain to shock or arrhythmia. Persistent resting tachycardia, gallop, ECG change, troponin elevation or ventricular dysfunction should trigger monitored hospital care.
A seizure often has prolonged tonic-clonic activity, lateral tongue bite and post-ictal confusion, but syncopal hypoperfusion can cause a few myoclonic jerks. Event chronology and recovery matter more than the presence of movement alone.
Family history must be specific. Ask who died, at what age, during what activity, whether post-mortem findings exist, and about cardiomyopathy, implanted defibrillators, channelopathy, unexplained drowning, single-vehicle crashes and epilepsy diagnoses.
The 12-lead ECG is high value when interpreted carefully. QT must be corrected and manually checked when the tracing or history is concerning; fever can reveal Brugada changes, and a normal resting ECG cannot exclude catecholaminergic arrhythmia.
Testing should follow the suspected mechanism. Troponin is not a generic chest-pain screen; D-dimer is not a routine childhood test; tilt testing, MRI, genetic testing and electrophysiology belong to selected specialist pathways.
Safety-netting includes what should trigger emergency help, activity restrictions, hydration actions and family screening. Reassurance is most credible when it explains the benign mechanism and documents why cardiac red flags are absent.
Key points
Most childhood syncope is vasovagal and most chest pain is musculoskeletal, respiratory or idiopathic, but rare cardiac disease is identified by event context, family history, examination and ECG rather than pain intensity.
Typical vasovagal syncope follows prolonged standing, heat, pain, fear, dehydration or seeing blood, with warmth, nausea, visual dimming and pallor before brief loss of posture and rapid recovery when supine.
Cardiac syncope is more concerning during exertion or swimming, while supine, after sudden noise or emotion, with palpitations or chest pain, with no prodrome, or in known cardiac disease.
Ask a witness to reconstruct position, activity, prodrome, colour, pulse or breathing if observed, movements, tongue biting, duration, recovery and injury; brief jerks can occur during cerebral hypoperfusion and do not prove epilepsy.
Chest-wall pain is focal, reproducible by palpation or movement and often follows cough, exercise or minor trauma. Cardiac pain is rare but exertional association, syncope, palpitations or cardiac risk history mandates referral.
Initial assessment includes full observations, lying and standing heart rate and blood pressure when safe, four-limb pulses, cardiac and neurological examination, hydration, glucose and a 12-lead ECG for red-flag or unexplained events.
Aetiology
01
Reflex vasovagal syncope
Autonomic vasodilatation with variable bradycardia reduces cerebral perfusion after standing, heat, pain, fear, dehydration or emotional stress.
02
Cardiac electrical disease
Inherited channelopathy, accessory pathways, conduction block or acquired myocardial irritation can cause abrupt tachyarrhythmia or bradyarrhythmia and collapse.
03
Structural flow limitation
Cardiomyopathy, outflow obstruction, pulmonary hypertension, coronary anomaly and congenital repair can prevent cardiac output rising appropriately during exercise.
04
Non-cardiac chest pain
Costochondral, muscular, respiratory, gastrointestinal and anxiety-related mechanisms account for most reported pain in otherwise well children.
Pathophysiology
1
Transient cerebral hypoperfusion
A sudden fall in pressure or output briefly deprives the brain of flow, causing loss of tone and sometimes short hypoxic jerks.
2
Orthostatic pooling
Standing shifts blood to lower limbs; inadequate vasoconstriction or volume allows tachycardia, visual dimming and presyncope.
3
Exercise-triggered arrhythmia
Adrenergic stimulation can provoke ventricular rhythm in susceptible channels or scar, abruptly reducing effective output during exertion.
4
Myocardial oxygen imbalance
Coronary anomaly, aneurysm thrombosis or severe hypertrophy can limit myocardial supply during increased demand and cause pain, arrhythmia or collapse.
Clinical features and red flags
Vasovagal sequence
Standing or emotional trigger, warmth, nausea, pallor and visual dimming precede a brief faint with prompt recovery supine.
Exertional cardiac event
Collapse during rather than after exercise, especially with chest pain or palpitations, is a high-priority cardiac pattern.
Supine or startle event
Fainting while lying down or after sudden sound or intense emotion raises inherited arrhythmia concern.
Chest-wall pain
Focal pain reproducible by pressure, arm movement or deep breath with a normal cardiac assessment favours musculoskeletal origin.
Inflammatory cardiac pain
Persistent pain with fever, breathlessness, disproportionate tachycardia, positional change, gallop or ECG abnormality suggests myocarditis or pericarditis.
Inherited-risk pedigree
Young sudden death, drowning, defibrillator, cardiomyopathy, channelopathy or unexplained seizure in relatives mandates specialist family assessment.
Red flags requiring action
Syncope during exercise, while swimming, while supine or without a typical prodrome requires urgent cardiac assessment and temporary restriction from strenuous activity.
Syncope preceded by palpitations, exertional chest pain or breathlessness, or followed by injury or prolonged physiological compromise raises arrhythmia or structural obstruction.
Investigations
01Initial event history, examination and bedside glucoseFirst step
Why
Classify syncope, detect current instability and identify neurological, metabolic, cardiac or injury clues.
Interpretation and limitations
A complete typical vasovagal sequence with normal findings is reassuring; any cardiac red flag changes the pathway.
02Lying and standing heart rate and blood pressure
Why
Assess orthostatic physiology in a stable child old enough to cooperate.
Interpretation and limitations
Interpret with symptoms, hydration, age and technique; an abnormal response does not explain exertional or supine red flags automatically.
Use when history, examination, ECG or known disease indicates; a normal echo does not exclude every electrical disorder.
05
Differential diagnosis
01
Epileptic seizure
Prolonged rhythmic movement, lateral tongue injury and sustained post-event confusion favour seizure, though convulsive movements can accompany syncope.
02
Hypoglycaemia or metabolic event
Sweating, behaviour change and prolonged impairment without rapid postural recovery requires immediate glucose and metabolic assessment.
03
Breath-holding or reflex anoxic event
A pain or fright trigger with crying, pallor or cyanosis occurs in younger children but red flags still require cardiac exclusion.
04
Musculoskeletal chest pain
Local tenderness reproduced by movement or palpation after cough, sport or minor trauma supports a chest-wall origin.
05
Respiratory or gastrointestinal pain
Wheeze, cough, fever, pleuritic features, reflux or dysphagia redirects testing while preserving cardiac review when exertional or syncopal red flags coexist.
Management
01EmergencyResuscitate and document rhythmFirst stepThe child is unresponsive, not breathing normally, shocked or has a sustained dangerous rhythm.+
1Start paediatric life support, attach an AED or defibrillator and follow the documented rhythm algorithm.
2If a pulse remains, monitor continuously, check glucose, obtain vascular access and treat shock or arrhythmia with senior help.
3Arrange urgent echocardiography and targeted myocardial, coronary, pulmonary or aortic assessment after immediate stabilisation.
02Cardiac red flagRestrict activity and refer urgentlySyncope occurs during exercise, supine or with palpitations or chest pain, or family, examination or ECG risk is present.+
1Stop strenuous and competitive exercise pending paediatric cardiology assessment and give emergency recurrence advice.
2Obtain and clinically review a 12-lead ECG and arrange echocardiography, rhythm or exercise testing according to the phenotype.
Complications
01
Sudden cardiac arrest
Malignant ventricular arrhythmia or severe structural obstruction can progress from syncope to pulseless collapse without timely recognition.
02
Traumatic injury
Unprotected loss of posture can cause head, dental or limb injury, especially when no prodrome permits protective action.
03
Missed inherited family disease
Failing to construct a pedigree can leave siblings and parents unaware of a treatable cardiomyopathy or channelopathy.
04
Unnecessary restriction and anxiety
Over-investigation of benign symptoms can reinforce fear, school absence and inactivity when a clear explanation and graded return are more appropriate.
05
Myocardial injury progression
Unrecognised myocarditis or coronary ischaemia can advance to ventricular failure, malignant arrhythmia, thrombosis or irreversible damage.
Monitoring and follow-up
Document event frequency, activity and posture, prodrome, duration, injury and recovery; a symptom diary can identify changing patterns and triggers.
For vasovagal episodes, review hydration, meals, sleep, menstrual blood loss, anaemia risk and functional impact before considering further intervention.
For red-flag symptoms, maintain activity restriction until the responsible cardiac service documents an individual return-to-exercise plan.
Check that ambulatory monitoring duration matches event frequency and review tracings rather than accepting an automated label alone.
Follow inherited-disease plans for serial ECG, imaging, exercise testing, medicines, fever management and cascade family screening.
After myocarditis or inflammatory cardiac disease, use cardiology-directed ventricular, rhythm and return-to-sport surveillance rather than symptom resolution alone.
Special situations
During is different from after
Collapse at peak exertion is more concerning than a vasovagal faint immediately after stopping, although both require careful reconstruction.
Jerks do not prove epilepsy
Brief hypoxic myoclonus can occur in syncope; prolonged post-ictal confusion and event chronology provide better discrimination.
Normal tests have boundaries
A normal echocardiogram does not exclude channelopathy, and a short normal Holter does not exclude a rare intermittent arrhythmia.
Ask about drowning
Unexplained swimming death, single-vehicle crash or seizure label can reveal an inherited rhythm disorder hidden in family history.
Pain severity is not cardiac probability
Severe reproducible chest-wall pain can be benign, while important exertional ischaemia may be described vaguely by a child.
Common pitfalls
01
Do not label an exertional or supine collapse vasovagal without cardiac assessment.
02
Do not stop the family history at the words no heart disease; ask specifically about young sudden death and drowning.
03
Do not diagnose epilepsy from a few syncopal jerks without examining prodrome and recovery.
04
Do not trust automated QTc or ECG interpretation when the phenotype is concerning.
05
Do not use a normal echocardiogram to exclude electrical cardiac disease.
06
Do not order troponin as a routine reassurance test for every child's chest pain.
07
Do not allow strenuous exercise while exertional syncope or sudden-death risk remains unexplained.
08
Do not over-medicalise a clear benign episode without explaining prevention and return red flags.
Read the paediatric ECG systematically for rate and rhythm, PR and QRS, pre-excitation, heart block, QTc, Brugada pattern, hypertrophy and ST-T changes; machine interpretation does not replace clinician review.
Echocardiography is targeted to abnormal examination or ECG, exertional symptoms, known disease or a concerning family phenotype; it is not a routine reassurance test for every reproducible chest pain.
Ambulatory rhythm monitoring is useful when symptom frequency matches the device duration; an exercise test can assess exertional arrhythmia or outflow symptoms under specialist supervision.
Manage uncomplicated vasovagal episodes with education, regular fluid and meals, trigger avoidance, early lying flat with legs raised and physical counter-pressure manoeuvres in an older child.
A child with sudden-death red flags should avoid competitive or strenuous exercise until paediatric cardiology or inherited-cardiac assessment defines risk and gives an individual activity plan.
A first-degree relative with sudden unexplained death under 40, inherited arrhythmia, cardiomyopathy, unexplained drowning or recurrent seizure-like collapse changes referral urgency.
Abnormal murmur, gallop, hypertension, weak femoral pulses, heart-failure signs or an abnormal ECG makes a benign vasovagal label unsafe.
Persistent chest pain with fever, tachycardia out of proportion, breathlessness, troponin rise, positional pain or a recent viral illness suggests myocarditis or pericarditis.
Known congenital heart disease, Kawasaki coronary disease, connective-tissue aortopathy, sickle cell disease, malignancy or stimulant exposure lowers the threshold for same-day assessment.
Ambulatory ECG or event recorder
Why
Capture intermittent palpitations or collapse and correlate symptom with rhythm.
Interpretation and limitations
Choose duration according to event frequency; a symptom-free short Holter cannot exclude a rare arrhythmia.
06Supervised exercise test
Why
Evaluate exercise-triggered symptoms, blood pressure and catecholamine-dependent rhythm.
Interpretation and limitations
Specialist testing is indicated for exertional red flags and should not be replaced by unsupervised return to sport.
Select from phenotype and family lineage; broad testing without a clinical question creates false positives and false reassurance.
3Route the family through inherited-cardiac and genetics services when sudden death or a known familial diagnosis is present.
03VasovagalBuild a prevention planThe history is typically reflex, examination and ECG when indicated are normal, and no red flag is present.+
1Explain the mechanism and encourage regular fluids, meals, sleep and gradual conditioning, adjusting salt only within individual clinical advice.
2Teach early recognition, lying flat with legs raised and counter-pressure manoeuvres for an older child.
3Review if episodes become exertional, occur supine, lose their prodrome, cause injury or develop palpitations, pain or prolonged recovery.
04Likely non-cardiac painTreat cause and safety-netPain is reproducible or linked to cough, movement or reflux with a normal cardiorespiratory assessment and no risk feature.+
1Address the musculoskeletal, respiratory or gastrointestinal cause and use age-appropriate analgesia when indicated.
2Avoid routine troponin, radiography or echocardiography without a question supported by the presentation.
3Advise urgent reassessment for exertional pain, syncope, palpitations, breathlessness, fever-related deterioration or persistent severe pain.