Atrioventricular and bundle-branch block
Reading AV block and bundle-branch block on the ECG, where the block sits, reversible causes, and when to pace, including bifascicular block with syncope.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- AV block is graded by ECG pattern, but prognosis depends on the level: block in the AV node is usually benign and drug- or vagally mediated; block below the node (His-Purkinje) is unstable and can cause asystole.
- Mobitz II, advanced (high-grade) and complete heart block without a reversible cause need a pacemaker, with or without symptoms.
- Bundle-branch block matters as a marker of structural heart disease, a clue to infranodal disease when syncope occurs, and (LBBB) a reason for CRT in heart failure.
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Sources
- 2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapyEuropean Society of Cardiology (European Heart Journal, doi:10.1093/eurheartj/ehab364), 2021
- ESC clinical consensus statement on indications for conduction system pacingEuropean Society of Cardiology and European Heart Rhythm Association (EP Europace), 2025
- 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction DelayAmerican College of Cardiology, American Heart Association and Heart Rhythm Society (Circulation), 2018
- Cardiac Society of Australia and New Zealand (CSANZ) Position Statement on the Follow-Up of Cardiovascular Implantable Electronic Devices 2022AU/NZCardiac Society of Australia and New Zealand (Heart, Lung and Circulation 2022;31(8):1054-63, doi:10.1016/j.hlc.2022.05.001), 2022
- Assessing Fitness to Drive for commercial and private vehicle driversAU/NZAustroads and the National Transport Commission, 2022
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy