First-degree Atrioventricular Block

First-degree Atrioventricular Block

First-degree AV block, or PR prolongation, is a disease of the electrical conduction system of the heart in which the PR interval is lengthened beyond 0.20 seconds.

In first-degree AV block, the impulse conducting from atria to ventricles through the AV node is delayed and travels slower than normal. It has a prevalence in the normal (young adult) population of 0.65-1.1% and the incidence is 0.13 per 1000 persons.