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Second-degree atrioventricular block
Other Resources UpToDate PubMed

Second-degree atrioventricular block

Contributors: Young Ju Esther Lee MD, Ryan Hoefen MD, PhD
Other Resources UpToDate PubMed

Synopsis

Second-degree atrioventricular (AV) block refers to delayed electrical conduction from the atria to the ventricles that results in periodically nonconducted atrial beats. This can occur in a regular pattern (eg, in a 2:1 or 3:2 ratio of atrial beats to ventricular beats).

Second-degree AV block has 2 subtypes, which are referred to as Mobitz type I ("Wenckebach") and Mobitz type II. Type I block is characterized by a progressively increasing PR interval with consecutive beats culminating in a nonconducted beat, after which the PR interval returns to baseline and the pattern repeats. Mobitz type II has a constant PR interval (whether normal or prolonged) with periodic nonconducted P waves.

Potential underlying causes for second-degree AV block include myocardial ischemia, amyloidosis, sarcoidosis, endocarditis, Lyme carditis, hyperkalemia, AV blocking medications (beta blockers, nondihydropyridine calcium channel blockers, digoxin, and some anti-arrhythmic drugs), increased vagal tone, iatrogenic injury during cardiac surgery, percutaneous coronary intervention, and transcatheter aortic valve replacement.

Clinical presentation is variable. Asymptomatic presentation is common with Mobitz type I. Mobitz type II is more often associated with palpitations, fatigue, light-headedness, presyncope, or syncope. Patients with Mobitz type II block may also progress to complete heart block, sometimes intermittently, and have an increased mortality risk.

Related topics: first-degree atrioventricular block, complete atrioventricular block

Codes

ICD10CM:
I44.1 – Atrioventricular block, second degree

SNOMEDCT:
195042002 – Second degree atrioventricular block

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed:02/10/2020
Last Updated:05/19/2020
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Second-degree atrioventricular block
Second-degree atrioventricular block : Chest pain, Dizziness, Syncope, Dyspnea, Presyncope
Copyright © 2021 VisualDx®. All rights reserved.