Understanding Atrioventricular Blocks, Part I: First-Degree and Second-Degree Atrioventricular Blocks

摘要

The electxocardiographic diagnosis of AV blocks presents a challenge to 8 health care professionals who monitor cardiac rhythms. Much of the confusion exists as a result of differing definitions of the "degrees" of AV blocks in the literature, especially surrounding second-degree block. Many misconceptions exist about the definitions of type I and type II blocks and how these "types" differ from the "degrees" used in the AV block classification system. Additional sources of confusion and difference of opinion are (1) the concept of 2:1 conduction and (2) where to put blocks that involve failed conduction of 2 or more consecutive P waves.1 With this much uncertainty and difference of opinion among the experts, it is no wonder that instructors have a hard time explaining and teaching these concepts to students in cardiac arrhythmia interpretation classes.