Oct 1, 1996

Alternation of atrioventricular nodal conduction time during atrioventricular reentrant tachycardia: are dual pathways necessary?

Journal of Cardiovascular Electrophysiology
F AmellalJ Billette


Alternation of atrial cycle length and AV nodal conduction time (NCT) is often observed during AV reentrant tachycardia. Both AV nodal dual pathway and rate-dependent function have been postulated to be involved in this phenomenon. This study was designed to determine the respective role of these two mechanisms in the alternation observed in an in vitro model of orthodromic AV reentrant tachycardia. The tachycardia was produced by detecting each His-bundle activation and stimulating the atrium after a retrograde delay, thereby simulating retrograde pathway conduction, in six isolated rabbit heart preparations. After a 5-minute stabilization period at a fast rate, the retrograde delay was decremented by 2 msec every minute until nodal blocks occurred. We observed a sequential alternation of the cycle length and NCT in four preparations in the short retrograde delay range. The magnitude of the alternation gradually increased as the retrograde delay was decreased and reached 4.6 +/- 0.5 msec during 1:1 conduction. The alternation increased further just prior to termination of the tachycardia by an AV nodal block. None of the preparations showed discontinuous AV nodal recovery curves. Moreover, an electrode positioned over the endo...Continue Reading

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Mentioned in this Paper

Biochemical Pathway
Leg Length Inequality
Atrioventricular Block
Structure of Atrioventricular Node
Re-entrant Atrioventricular Tachycardia
NODAL gene
Entire Atrium
Heart Atrium
Specimen Type - Electrode

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