Jul 28, 2007

Dependence of AV nodal function curves on the selected recovery index: pivotal role of pretest conduction time

Journal of Cardiovascular Electrophysiology
Rafik TadrosJacques Billette

Abstract

Rate-dependent AV nodal function is often assessed with premature protocols. Conduction curves generated from nodal responses differ with the selected recovery index (atrial-atrial, AA, or His-atrial interval, HA). We propose that these differences arise from changes in pretest conduction time that affect nodal recovery time assessment. We varied the basic (S(1)S(1)), pretest (S(1)S(2)), and test (S(2)S(3)) cycle length with S(1)S(2)S(3) protocols, and analyzed nodal responses as AA (A(3)H(3) vs A(2)A(3)) and HA (A(3)H(3) vs H(2)A(3)) curves in six rabbit heart preparations. Any A(2)H(2) (pretest conduction time) prolongation bodily shifted AA curve rightward and HA curve leftward, regardless of prevailing basic cycle length. A prolonged A(2)H(2) caused all A(3)H(3) to occur at longer A(2)A(3) and shorter H(2)A(3,) as compared with control. When corrected for these shifts, AA and HA curves displayed similar recovery and fatigue properties. To further investigate the possibility that nodal recovery time varies beyond that imposed by pacing interval, six additional preparations were subjected to 5-minute frequency step protocols during which a long cycle was introduced after every 30th short cycle. After each long cycle, nodal co...Continue Reading

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Citations

Mentioned in this Paper

In Silico
Computer Assisted Diagnosis
Sveinsson Chorioretinal Atrophy
Cardiac Conduction System
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NODAL gene
Fatigue
Heart Atrium
Cardiac Conduction
Nerve Impulses

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