Atrioventricular block (first, second, or third degree)

Etiology

Increased vagal tone (first degree or Mobitz type I)
Drugs: digitalis, calcium channel blockers, beta blockers, clonidine, other sympatholytics, amiodarone, other antiarrhythmics
Age-related conduction system fibrosis or calcification (Lev's disease)
Cardiac infiltrative disease (e.g., amyloid, sarcoidosis, hemochromatosis)
Myocardial ischemia or infarction
Myocarditis
Chagas' disease

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