atrioventricular block second degree atrioventricular block 2026-07-20T12:45:16Z MP:0031757 2nd-degree AV block MPheno.ontology Second-degree AV blocks can be further classified into Mobitz type 1 (Wenckebach) or Mobitz type 2, which can be distinguished by examining the PR interval. second-degree atrioventricular block second-degree AV block an intermittent atrioventricular (AV) block with failure of some atrial impulses to conduct to the ventricles, leading to skipped beats; some but not all atrial impulses are conducted through the AV node and trigger ventricular contraction