Evidence that AV nodal re-entrant tachycardia does not require participation of the entire AV node.

Electrophysiologic studies in a case of AV nodal re-entrant tachycardia showed that a programmed atrial premature depolarization induced during the tachycardia did not change the tachycardia cycle but caused a delay in the following atrial echo. Analysis of such a phenomenon suggests that the atrial premature depolarization was conducted to the upper part of the AV node but not to the site of the re-entry. Therefore, AV nodal re-entry can persist without the participation of the upper part of the AV node. This case illustrates that the upper common pathway connecting the dual AV nodal pathways cranially is most likely located within the AV node and consists of AV nodal tissue.