"AV nodal" reentry: Part I: "AV nodal" reentry revisited.

This review is the first of a two-part series of articles on "atrioventricular [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 circuit is confined to the AV node, or consists in part of extranodal components. Most of the evidence supports the concept that atrial tissue is an essential link in the reentrant pathway. Arguments will be presented to indicate that within the AV node, the separation between antegrade and retrograde pathways is functional, not anatomical, and that both pathways are in electrotonic contact.