Affiliation:
1. From the Krannert Institute of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Ind.
Abstract
Abstract
—The reentrant pathways underlying different types of atrioventricular (AV) nodal reentrant tachycardia have not yet been elucidated. This study was performed to optically map Koch’s triangle and surrounding atrial tissue in an isolated canine AV nodal preparation. Multiple preferential AV nodal input pathways were observed in all preparations (n=22) with continuous (73%, n=16) and discontinuous (27%, n=6) AV nodal function curves (AVNFCs). AV nodal echo beats (EBs) were induced in 54% (12/22) of preparations. The reentrant circuit of the slow/fast EB (36%, n=8) started as a block in fast pathway (FP) and a delay in slow pathway (SP) conduction to the compact AV node, then exited from the AV node to the FP, and rapidly returned to the SP through the atrial tissue located at the base of Koch’s triangle. The reentrant circuit of the fast/slow EB (9%, n=2) was in an opposite direction. In the slow/slow EB (9%, n=2), anterograde conduction was over the intermediate pathway (IP) and retrograde conduction was over the SP. Unidirectional conduction block occurred at the junction between the AV node and its input pathways. Conduction over the IP smoothed the transition from the FP to the SP, resulting in a continuous AVNFC. A “jump” in AH interval resulted from shifting of anterograde conduction from the FP to the SP (n=4) or abrupt conduction delay within the AV node through the FP (n=2). These findings indicate that (1) multiple AV nodal anterograde pathways exist in all normal hearts; (2) atrial tissue is involved in reentrant circuits; (3) unidirectional block occurs at the interface between the AV node and its input pathways; and (4) the IP can mask the existence of FP and SP, producing continuous AVNFCs.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Reference22 articles.
1. Electrophysiology of the Atrio-AV Nodal Inputs and Exits in the Normal Dog Heart.
2. Otomo K Wang Z Lazzara R Jackman WM. Atrioventricular nodal reentrant tachycardia: electrophysiological characteristics of four forms and implications for the reentrant circuit. In: Zipes DP Jalife J eds. Cardiac Electrophysiology: From Cell to Bedside . 3rd ed. Philadelphia Pa: WB Saunders Co; 2000:504–521.
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