英文原文：
ElectrocardiographicMarkersofPhase3
andPhase4AtrioventricularBlockand
ProgressiontoCompleteHeartBlock
PREAMBLE
Phase3and4blocksrefertoabnormalitiesofconduction[usuallyinreferencetotheHis-Purkinjesystem(HPS)],dueontheonehandtoimpingementofin