Paeds · cardiology
Bradyarrhythmias, heart block and pacing
Also known as Bradycardia · Atrioventricular block · AV block · Complete heart block · Congenital heart block · Heart block · Sinus node dysfunction · Sick sinus syndrome · Paediatric pacing · Pacemaker
Fellowship guide to bradyarrhythmias, atrioventricular block and cardiac pacing in children: how to read the slow rhythm on a 12-lead ECG, the anatomy of first-degree, Mobitz I, Mobitz II and third-degree block, why maternal anti-Ro antibodies scar the fetal AV node, the post-surgical AV block that will not recover, the stable-versus-unstable resuscitation fork, atropine and transcutaneous pacing, and the permanent pacemaker indications — including the 2021 PACES consensus, the ACCF/AHA/HRS and ESC pacing guidelines, epicardial versus transvenous versus leadless systems, and the lifelong care of the paced child.
On this page
Study tools
Your progress
Saved on this device.
Practise this topic
Target exams
Red flags
- A child with an abnormally slow heart rate plus symptoms — fatigue, poor feeding, exercise intolerance, syncope, or heart failure — has symptomatic bradycardia and is complete heart block until proven otherwise on a 12-lead ECG
- Mobitz II second-degree AV block has a constant PR interval with suddenly dropped beats, a wide QRS, and a real risk of progression to complete heart block — it is a pacing indication even if the child is currently asymptomatic
- Post-operative AV block persisting beyond seven to ten days after cardiac surgery is considered permanent and is a Class I indication for permanent pacing — do not keep waiting for it to recover
- In the unstable bradycardic child, atropine alone is unreliable for AV block — go to transcutaneous or transvenous pacing early; atropine helps sinus bradycardia but does not fix a blocked AV node
- Congenital complete heart block from maternal anti-Ro/SSA antibodies is permanent — the fibrotic AV node does not recover, and most children will need lifelong pacing to prevent syncope and sudden death
Life stages
Care settings
Clinical exam formats
Board mappings
- Cardiology
- Bradyarrhythmias and conduction disorders
- Atrioventricular block
- Paediatric pacing
- Paediatric Cardiology — conduction disorders and device therapy
- General Paediatrics learning goal — recognise symptomatic bradycardia
- Lifelong pacemaker surveillance and complication management
- Clinical Applications
- Bradyarrhythmias and pacing
- Long Cases
- Short Cases
- Communication scenarios
- Cardiology: recognises and manages bradyarrhythmia and atrioventricular block
- Resuscitation of the unstable bradycardic child
- Lifelong follow-up of the paced child and family
- Foundation of Practice (FOP)
- Applied Knowledge in Practice (AKP)
- Conduction disorders and pacing
- Clinical
- History
- Communication
- Cardiovascular examination and ECG interpretation
- General Pediatrics Content Outline — Domain 9: Cardiology
- Subspecialty: Pediatric Cardiology — arrhythmia and device therapy
- Recognition and management of paediatric bradycardia
- Patient Care 1: History and Physical Examination
- Patient Care 4: Clinical Reasoning
- Medical Knowledge 1: Clinical Knowledge of bradyarrhythmias and pacing
- Systems-Based Practice 1: multidisciplinary device and transition care
- Medical Expert
- Collaborator
- Pediatrics: Core EPA — recognise and stabilise paediatric bradycardia
Overview & Definition
Picture the four-year-old brought in because she "tires on the trampoline and keeps needing to sit down." The GP hears a heart rate of forty-five and sends her to the emergency department, where the triage note reads "fit and healthy, likely athletic." That child carries the whole story of complete heart block: an abnormally slow rate dismissed as fitness, a slow ventricular escape rhythm holding her circulation together, and a single twelve-lead ECG that would change everything. Bradycardia in a child is never normal in the way that it can be in a conditioned adult athlete, and the question is always the same — where is the block, what caused it, and does she need a pacemaker. [4] [1]
A bradyarrhythmia is any pathologically slow heart rhythm — conventionally a rate below the age-adjusted normal range that is inadequate for the child's cardiac output. The two mechanisms are failure of impulse formation at the sinus node (sinus node dysfunction, sometimes called sick sinus syndrome in children) and failure of impulse conduction through the atrioventricular node or His-Purkinje system (atrioventricular block). The latter is the clinically important entity in paediatrics because it is the one that produces symptomatic, unpredictable bradycardia and carries a risk of sudden death when the escape rhythm fails. [4] [2]
The clinical importance of paediatric bradycardia rests on three facts. It is symptomatic: a slow rate in a child who needs a high cardiac output to grow and play shows up as fatigue, poor feeding, exercise intolerance, syncope, or heart failure rather than as a number on a monitor. It is under-recognised: a slow pulse is routinely attributed to fitness or to medications rather than investigated with an ECG, and the first presentation of complete heart block is sometimes a Stokes-Adams syncopal attack or sudden death. And it is treatable: the AV node and His-Purkinje system have a finite capacity to recover, but once the block is permanent, a pacemaker restores rate, abolishes symptoms, and prevents sudden death with excellent long-term outcomes. [5] [7]
References12ShowHide
- [1]Shah MJ, Silka MJ, Silva JNA, et al. 2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients. JACC Clin Electrophysiol, 2021.PMID 34794667
- [2]Epstein AE, DiMarco JP, Ellenbogen KA, Estes NA 3rd, Freedman RA, et al. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol, 2013.PMID 23265327
- [3]Brignole M, Auricchio A, Baron-Esquivias G, Bordachar P, Boriani G, et al. 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Eur Heart J, 2013.PMID 23801822
- [4]Baruteau AE, Pass RH, Thambo JB, Behaghel A, Le Franc P, et al. Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management. Eur J Pediatr, 2016.PMID 27351174
- [5]Michaëlsson M, Jonzon A, Riesenfeld T Isolated congenital complete atrioventricular block in adult life. A prospective study. Circulation, 1995.PMID 7634461
- [6]Eronen M, Sirèn MK, Ekblad H, et al. Short- and long-term outcome of children with congenital complete heart block diagnosed in utero or as a newborn. Pediatrics, 2000.PMID 10878154
- [7]Eronen M Long-term outcome of children with complete heart block diagnosed after the newborn period. Pediatr Cardiol, 2001.PMID 11178669
- [8]Mycinski F, Waldmann V, Kyndt F, et al. Late outcomes of congenital and childhood non-immune, isolated atrioventricular block: a French nationwide retrospective cohort study. Europace, 2025.PMID 40067976
- [9]Mawad W, Hornberger L, Cuneo B, et al. Outcome of Antibody-Mediated Fetal Heart Disease With Standardized Anti-Inflammatory Transplacental Treatment. J Am Heart Assoc, 2022.PMID 35001672
- [10]Trucco SM, Jaeggi E, Cuneo B, Moon-Grady AJ, Silverman E, et al. Use of intravenous gamma globulin and corticosteroids in the treatment of maternal autoantibody-mediated cardiomyopathy. J Am Coll Cardiol, 2011.PMID 21292131
- [11]Fortescue EB, Berul CI, Cecchin F, Walsh EP, Alexander ME Patient, procedural, and hardware factors associated with pacemaker lead failures in pediatrics and congenital heart disease. Heart Rhythm, 2004.PMID 15851146
- [12]Shah MJ, Borquez AA, Cortez D, et al. Transcatheter Leadless Pacing in Children: A PACES Collaborative Study in the Real-World Setting. Circ Arrhythm Electrophysiol, 2023.PMID 37039017