Published online before print June 30, 2003, doi: 10.1161/01.CIR.0000080286.87137.32
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(Circulation. 2003;108:231.)
© 2003 American Heart Association, Inc.
Basic Science Reports |
Reentrant Circuits in the Canine Atrioventricular Node During Atrial and Ventricular Echoes
Electrophysiological and Histological Correlation
From the Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, and the Heart Lung Center, University Medical Center Utrecht, the Netherlands (P.L., T.K., R.N.W.H., M.J.J.); the National Heart and Lung Institute, Imperial College, London, UK (S.Y.H.); the Department of Cardiology and Angiology, University of Muenster, Germany (P.L., G.B.); and the Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.M.T.d.B.)
Correspondence to Peter Loh, MD, Heart Lung Center Utrecht, University Medical Center, Postbox 85500, 3508 GA Utrecht, The Netherlands. E-mail p.loh{at}hli.azu.nl
Background— The anatomic-electrophysiological correlation of AV nodal reentry is unclear. To localize reentrant circuits during atrial and ventricular echoes and to characterize sites of slow conduction and block, we correlated histology with electrophysiology of the AV node.
Methods and Results— In 10 isolated dog hearts, extracellular electrical activity was recorded in Koch’s triangle at 208 or 247 sites (interelectrode distance, 0.5 and 0.3 mm) after removal of 0.7 to 1.5 mm of overlying atrial tissue. Resection did not affect refractory periods. Five hearts were subjected to histology. Complete atrial echoes were induced in 1 heart, incomplete atrial echoes in 5 hearts. Unidirectional conduction block occurred at the atrial–transitional cell junction in the superior area. Zones of slow conduction arose at the atrial–transitional or the transitional–compact node junction in the inferior area. Complete reentrant circuits of ventricular echoes were obtained in 5 hearts. Unidirectional conduction block occurred at the compact node–transitional cell junction in the superior area. Localized zones of slow conduction arose at the junctions between the different types of tissue in the inferior area.
Conclusions— In the dog heart, tissue architecture and functional dissociation between the inferior and the superior region of the AV node enable dual physiology and reentry. Slow conduction and functional conduction block occur at the junctions between the different types of tissue in the AV nodal area. Atrial echoes were enabled by conduction block at the atrial-transitional cell junction, whereas during ventricular echoes conduction block occurred at the compact node-transitional cell junction.
Key Words: atrioventricular node • reentry • mapping • electrophysiology
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