| Abstract: | To evaluate the role of perinodal tissue in the genesis of atrioventricular (AV) nodal reentry, echo beats were induced by programmed stimulation in nine superfused rabbit AV nodal preparations which included the crista terminalis (CT) input, interatrial septal (IAS) input and perinodal atrial tissues in addition to the AV node. Two patterns of AV reentry were observed: In six preparations, premature response was blocked within the AV node, but anterograde conduction continued along the perinodal fibers and entered the AV node by way of another input region. Reentry occurred via retrograde nodal conduction to the initial input and subsequently conducted within the perinodal region. In three preparations, premature beat elicited by CT stimulation was blocked in the perinodal tissues near the CT, conducted slowly in an anterograde fashion through the AV node. To complete the reentry circuit, it exited at the IAS region and conducted in retrograde fashion via the perinodal tissues to reenter the node at the CT. Moreover, in four other preparations, surgical interruption of the perinodal tissue prevented reinitiation of reentrant phenomena. Thus, the critical role of the perinodal tissues as a necessary link in AV nodal reentry was demonstrated in this preparation. |
