first-degree atrioventricular (AV) block
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Introduction
First-degree AV block generally results from a delay of impulse propagation through the AV node. Less frequently, a delay of impulse propagation through the atrium or the His-Purkinje system (bundle branch block) is the culprit.
Etiology
- increased vagal tone
- antiarrhythmic agents
- electrolyte abnormalities
- myocardial ischemia
- conduction system disease
Clinical manifestations
- generally asymptomatic
- may exacerbate CHF
Diagnostic procedures
- electrocardiogram: PR interval >200 ms
Complications
- need for pacemaker implant (HR=3)[2]
- atrial fibrillation (HR=2)[2]
- increased all-cause mortality (HR=1.4)[2]
Management
- therapy not indicated in asymptomatic patient
- bifascicular block not an indication for pacemaker[3]
- correct electrolyte abnormalities
- discontinue pharmacologic agents that affect AV conduction
More general terms
References
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 139
- ↑ 2.0 2.1 2.2 2.3 Cheng S et al Long-term Outcomes in Individuals With Prolonged PR Interval or First-Degree Atrioventricular Block JAMA. 2009;301(24):2571-2577. <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/19549974 <Internet> http://jama.ama-assn.org/cgi/content/short/301/24/2571
- ↑ 3.0 3.1 Medical Knowledge Self Assessment Program (MKSAP) 17, 18, American College of Physicians, Philadelphia 2015, 2018.