AV BLOCK

Impaired conduction from atria to ventricles may be structural and permanent, or reversible (e.g., autonomic, metabolic, drug-related)—see Table 124-2.
TABLE 124-2: Etiologies of Atrioventricular Block
Autonomic
Carotid sinus hypersensitivityVasovagal
Metabolic/Endocrine
HyperkalemiaHypothyroidism
HypermagnesemiaAdrenal insufficiency
Drug-Related
Beta blockersAdenosine
Calcium channel blockersAntiarrhythmics (class I and III)
DigitalisLithium
Infectious
EndocarditisTuberculosis
Lyme diseaseDiphtheria
Chagas’ diseaseToxoplasmosis
Syphilis 
Heritable/Congenital
Congenital heart diseaseKearns-Sayre syndrome
Maternal SLEMyotonic dystrophy and other muscular dystrophies
Inflammatory
SLEMCTD
Rheumatoid arthritisScleroderma
Infiltrative
AmyloidosisHemochromatosis
Sarcoidosis 
Neoplastic/Traumatic
LymphomaRadiation
MesotheliomaCatheter ablation
Melanoma 
Degenerative 
Lev’s diseaseLenègre’s disease
Coronary Artery Disease 
Acute MI 
Abbreviations: MCTD, mixed connective tissue disease; MI, myocardial infarction.

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