AV NODAL REENTRY .1. AV NODAL REENTRY REVISITED

This review is the first of a two-part series of articles on ''atriove ntricular [AV] nodal reentry.'' The early clinical literature as well as the experimental studies are reviewed, and more recent morphologic data are presented, with the aim of clarifying whether the reentrant c ircuit is confined to the AV node, or consists in part of extranodal c omponents. Most of the evidence supports the concept that atrial tissu e is an essential link in the reentrant pathway. Arguments will be pre sented to indicate that within the AV node, the separation between ant egrade and retrograde pathways is functional, not anatomical, and that both pathways are in electrotonic contact.