Reentrant circuits in the canine atrioventricular node during atrial and ventricular echoes: electrophysiological and histological correlation.
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.


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.
Loh
Peter
P
Experimental and Molecular Cardiology Group, Academic Medical Center, Amsterdam, The Netherlands. p.loh@hli.azu.nl
Ho
Siew Yen
SY
Kawara
Tokuhiro
T
Hauer
Richard N W
RN
Janse
Michiel J
MJ
Breithardt
Günter
G
de Bakker
Jacques M T
JM
D000818:Animals; D016275:Atrial Function / Q000502:physiology*; D001283:Atrioventricular Node / Q000502:physiology*; D018780:Body Surface Potential Mapping; D002036:Bundle of His / Q000502:physiology; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D016276:Ventricular Function / Q000502:physiology*