Atrioventricular block
Cardiology
Also known as: AV block · AV-Block (Grad I-III, Mobitz) · AV blok · Atrioventricular (AV) block: degrees and types
What it is for
Atrioventricular (AV) block: delay or failure of conduction from the atria to the ventricles, classified on the ECG by degree:
Classification
| Category | Description |
|---|---|
| First-degree AV block | PR interval >200 ms with every P wave conducted (1:1); a conduction delay rather than a true block. |
| Second-degree AV block, type I (Mobitz I, Wenckebach) | a single non-conducted P wave after gradual PR prolongation; the PR intervals before and after the blocked beat differ. |
| Second-degree AV block, type II (Mobitz II) | a single non-conducted P wave with constant PR intervals before and after the blocked beat, at a stable sinus rate. |
| 2:1 AV block | every second P wave is not conducted; it cannot be classed as type I or type II from the surface ECG alone. |
| Advanced (high-grade) AV block | two or more consecutive P waves at a constant physiological rate are not conducted, but some AV conduction remains. |
| Third-degree (complete) AV block | no P wave is conducted; atria and ventricles beat independently (complete AV dissociation). |
Source
2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay
ACC/AHA/HRS · Circulation 2019;140:e382-e482 (Kusumoto FM et al.)
DOI: 10.1161/CIR.0000000000000628
PMID: 30586772
- Edition
- ACC/AHA/HRS 2018 bradycardia and conduction delay guideline terminology (standard ECG definitions)
- Checked on
Summary of the published classification in our own words. Not a substitute for the original publication.
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