Syncope and orthostatic intolerance

The idea that holds the whole topic together is the separation of benign from dangerous collapse. A faint that happens after standing too long in a hot assembly hall, with pallor and nausea beforehand and a full recovery within a minute, is almost certainly vasovagal and is safe. A faint that happens mid-sprint, or in the swimming pool, or with no warning at all, or in a child whose father died at thirty, is cardiac until you have proved otherwise. ^{[5] [11]} Everything in this page — the history, the standing test, the ECG criteria, the management — serves that single triage decision.

This page covers the definition and the mechanism-based classification, the vasovagal and orthostatic-intolerance pathophysiology, the red-flag history and the orthostatal vital signs, the investigations (and the ones to avoid), the stepwise management of benign and of cardiac syncope, and the long-term follow-up and sport advice. It links to the long-QT, hypertrophic cardiomyopathy and sudden-cardiac-death leaves for the cardiac work-up, and to the seizure leaf for the seizure-versus-syncope distinction, rather than duplicating those pathways. ^{[6] [11]}

Overview & Definition

Syncope is a transient loss of consciousness — "transient" means it comes on fast and leaves fast — caused by a temporary failure of blood flow to the whole brain, with rapid, spontaneous and complete recovery. ^[1] The key words are global cerebral hypoperfusion: the whole brain is briefly starved, which is why recovery is complete and quick. A focal problem (a stroke) does not behave this way, and a brain that has seized does not recover in seconds.

A simple way to think about it at the bedside: the child was upright, the blood drained to the legs, the heart could not push enough back up to the brain, the brain switched off for a few seconds, the child fell, gravity and the supine posture refilled the heart, and the child woke up. That is the common pathway for almost every faint, whatever the trigger. ^[6]

Before going further, separate three terms the examiner uses interchangeably but should not. Syncope is the actual loss of consciousness. Presyncope is the warning — the lightheaded, nauseated, vision-greying feeling — without actually passing out; it shares the same mechanism and work-up as syncope. ^[2] Orthostatic intolerance is the broader basket of symptoms (lightheadedness, palpitations, nausea, fatigue, brain fog) that appear on standing and ease on lying down; syncope is only one possible end-point of it, and many adolescents with orthostatic intolerance never actually faint. ^{[8] [9]}

Why this matters clinically: most children you see will have presyncope or orthostatic intolerance rather than a true collapse, and the same triage logic — benign autonomic versus dangerous cardiac — applies to all of them. ^[9]

References13ShowHide

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2. [2]Yeom JS Pediatric syncope: pearls and pitfalls in history taking. Clin Exp Pediatr, 2023.PMID 36789491
3. [3]Zavala R; Moffa M; Stahlschmidt J; et al Pediatric Syncope: A Systematic Review. Pediatr Emerg Care, 2020.PMID 32530839
4. [4]Wang C; Wu L; Liao Z; et al Guidelines for the diagnosis and treatment of neurally mediated syncope in children and adolescents (revised 2024). World J Pediatr, 2024.PMID 39110332
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8. [8]Vernino S; Stiles LE; Low P; et al Postural orthostatic tachycardia syndrome (POTS): State of the science and clinical care from a 2019 National Institutes of Health Expert Consensus Meeting - Part 1. Auton Neurosci, 2021.PMID 34144933
9. [9]Soroken C; Lesavre N; Tard C; et al Postural tachycardia syndrome among adolescents. Arch Pediatr, 2022.PMID 35523634
10. [10]Kucharik AH; Maurer K The Relationship Between Hypermobile Ehlers-Danlos Syndrome (hEDS), Postural Orthostatic Tachycardia Syndrome (POTS), and Mast Cell Activation Syndrome (MCAS). Clin Rev Allergy Immunol, 2020.PMID 31267471
11. [11]Goldenberg I; Moss AJ; Zareba W Long QT syndrome. J Am Coll Cardiol, 2008.PMID 18549912
12. [12]Villafane J; FE; Baffa F; et al Loss of Consciousness in the Young Child. Pediatr Cardiol, 2021.PMID 33388850
13. [13]Cui Y; Qin H; Zhang L; et al Multivariate predictive model of the therapeutic effects of metoprolol in paediatric vasovagal syncope: a multi-centre study. EBioMedicine, 2025.PMID 39946834