AJP - Heart and Circulatory Physiology, Vol 233, Issue 1 44-H49, Copyright © 1977 by American Physiological Society
Effect of anomalous pathway location on rate of canine experimental A-V reentrant tachycardia
S. Teague, P. Denes, F. Amat-y-Leon and K. M. Rosen
The effect of anomalous pathway (AP) location and conduction time on the
cycle length (CL) and sustainability of paroxysmal A-V reentrant
tachycardia was studied in 15 dogs, using an anomalous pathway simulator
(APS). The APS was a programmable digital electronic circuit with ability
for unidirectional conduction, ventricular sensing, adjustable delay, and
atrial stimulation. Contiguous pairs of ventricular sensing electrodes were
placed along the A-V ring in each dog at the following sites: anterior,
posterior, and lateral right (AR, PR, and LR) and anterior, posterior, and
lateral left (AL, PL, and LL) and septal (S). There were significant
differences in the CL of tachycardias among the tested sites (P less than
0.01). The CL of tachycardias from the LL site was significantly longer and
from the PR site significantly shorter than that from the other sites (P
less than 0.05). These differences in CL of tachycardias in relation to the
AP location were explicable in terms of corresponding variation in
conduction times of the various components of the tachycardia circuit
(e.g., intra-atrial, A-V nodal, intraventricular conduction times). The
differences in magnitude of the CL of tachycardias, although significant,
were small. It was also found that all sites allowed maintenance of
tachycardias up to an AP conduction time of 10 ms. In 27% of experiments,
atrial refractoriness prevented sustained tachycardias at pathway delays of
1 ms. The relationship between AP conduction time and CL of tachycardias
was exponential.
