AJP - Heart and Circulatory Physiology, Vol 242, Issue 3 421-H428, Copyright © 1982 by American Physiological Society
Relation of canine atrial activation sequence to anatomic landmarks
H. Hayashi, R. L. Lux, R. F. Wyatt, M. J. Burgess and J. A. Abildskov
Activation sequence in the atria was investigated in 35 dogs. The atria
were studied as four regions, and activation sequence in one region was
determined in each experiment. In each region 60 electrograms were recorded
simultaneously from bipolar electrodes. The maximal first derivative of the
electrograms was taken as activation time. Dried atrial specimens, which
permitted identification of pectinate muscles, crista terminalis, and the
axis of fiber direction, were prepared. Nonuniform activation was
demonstrated with more rapid conduction over the long axis of fiber
direction and in Bachmann's bundle, crista terminalis, and pectinate
muscles. These regions of rapid conduction were the same during sinus
rhythm and ectopic and retrograde activation. Findings confirm the presence
of paths with relatively rapid conduction in the atria and demonstrate that
these are related to gross anatomic features. Findings also demonstrate
that the paths are accessible to activation from multiple sites rather than
insulated conduction paths with limited sites for entry and exit of
activation.
