What causes first-degree atrioventricular (AV) block?

Updated: Jan 06, 2020
  • Author: Jamshid Alaeddini, MD, FACC, FHRS; Chief Editor: Jose M Dizon, MD  more...
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The following are the most common causes of first-degree atrioventricular (AV) block:

  • Intrinsic AV node (AVN) disease

  • Enhanced vagal tone ("pathophysiologic AV block" [2] )

  • Acute myocardial infarction (MI), particularly acute inferior wall MI

  • Electrolyte disturbances (eg, hypokalemia, hypomagnesemia)

  • Drugs (especially those drugs that increase the refractory time of the AVN, thereby slowing conduction)

A number of specific disorders and events have been implicated (see below).

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