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Complex AV nodal dynamics during ventricular-triggered atrial pacing in humans
Journal Title
American Journal of Physiology-Heart and Circulatory Physiology
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Publication Date
2001-08-01
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Publication Volume
281
Publication Issue
2
Publication Begin
H865
Publication End
H872
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Abstract
In vitro experiments have shown that the complexity of atrioventricular nodal (AVN) conduction dynamics increases with heart rate. Although complex AVN dynamics (e.g., alternans) have been observed clinically, human AVN dynamics during rapid pacing have not been systematically investigated. We studied such dynamics during ventricular-triggered atrial pacing in 37 patients with normal AVN function (18 patients with dual AVN pathway physiology and 19 patients without). Alternans, which always resulted from single pathway conduction, occurred in 18 patients. In 16 patients (3 of whom also had alternans), quasisinusoidal AVN conduction oscillations occurred (mean frequency 0.02 Hz); such oscillations have not been previously reported. There were no significant differences in the dynamics for patients with or without dual AVN pathways. To illuminate the governing dynamic mechanism, a second atrial pacing trial was performed on 12 patients after autonomic blockade. Blockade facilitated alternans but inhibited oscillations. This study suggests that rapid AVN excitation in vivo can lead to autonomically mediated AVN conduction oscillations or single pathway alternans that are a function of inherent nonlinear dynamic AVN tissue properties.
Citation
Christini DJ, Stein KM, Markowitz SM, Mittal S, Slotwiner DJ, Iwai S, Lerman BB. Complex AV nodal dynamics during ventricular-triggered atrial pacing in humans. Am J Physiol Heart Circ Physiol. 2001 Aug;281(2):H865-72. doi: 10.1152/ajpheart.2001.281.2.H865. PMID: 11454592.