15. Atrioventricular Block
Published Online: 1 NOV 2012
Copyright © 2013 John Wiley & Sons, Ltd.
Bennett's Cardiac Arrhythmias: Practical Notes on Interpretation and Treatment, Eighth Edition
How to Cite
Bennett, D. H. (2013) Atrioventricular Block, in Bennett's Cardiac Arrhythmias: Practical Notes on Interpretation and Treatment, Eighth Edition, John Wiley & Sons, Ltd, Oxford. doi: 10.1002/9781118432389.ch15
- Published Online: 1 NOV 2012
- Published Print: 14 JAN 2013
Print ISBN: 9780470674932
Online ISBN: 9781118432389
- Atrioventricular (AV) block;
- Atrioventricular (AV) dissociation;
- Bilateral bundle branch disease;
Atrioventricular (AV) block is classified as first, second or third degree depending on whether conduction of atrial impulses to the ventricles is delayed, intermittently blocked or completely blocked. Second-degree AV block is subdivided into Mobitz I (Wenckebach) and Mobitz II types. With the former, there is progressive lengthening of the PR interval prior to non-conduction of an atrial impulse, whereas the PR interval of conducted atrial impulses is constant in Mobitz II. Bifascicular block may deteriorate intermittently or permanently to complete (i.e. trifascicular) AV block.
Causes of AV block include idiopathic fibrosis of the conduction tissues, myocardial infarction, aortic valve disease, congenital, cardiac surgery and haemochromatosis.
First-degree and Wenckebach block in young people and/or during sleep are usually due to high vagal tone and are benign. High-degree AV block may cause Stokes–Adams attacks (characterised by abrupt, brief losses of consciousness) or may cause sudden death.