Functional Mechanisms Underlying Tachycardia-Induced Sustained Atrial Fibrillation in a Chronic Dog Model

Abstract

Rapid atrial activation causes time-dependent decreases in ERP, conduction velocity, and wavelength, which, along with increased regional heterogeneity, provide a substrate for AF. The conduction abnormalities and increased regional heterogeneity previously noted in patients with AF may be a consequence, as well as a cause, of the tachyarrhythmia.

Differences in atrial fibrillation properties under vagal nerve stimulation versus atrial tachycardia remodeling

“…Gaspo et al 117,124 showed a reduction in CV in ATR dogs. However, CV measurements were done in the RPW, where we also didn't find significant differences in CV between CTL and ATR.…”

“…Similarly to the effects of VS, atrial tachycardia remodeling reduces the AERP, the AERP rate adaptation and the WL while increasing the AERP heterogeneity 27,41,74,105,117 . Nevertheless, the time course of AF promotion due to atrial tachycardia remodeling is slower than that of AERP changes, indicating the involvement of additional mechanisms 24 .…”

“…AF has been induced in different experimental models with either infusion of ACh in the sinus node artery 123 or by direct stimulation of the vagal cervical nerves. Similarly, atrial tachycardia remodeling reduces the atrial ERP, the ERP rate adaptation and the WL while increasing the ERP heterogeneity 27,41,74,105,117 .…”

“…Despite the undoubted progress in explaining causal factors and pathophysiological mechanisms leading to AF, many unanswered questions remain 4 . Therefore, many animal models have been developed, assisting continuously in the progress of our knowledge and in the acquisition of new important information 41,74,117,118 . Among them the "atrial tachycardia remodeling" (ATR)…”

“…Moreover, other experimental work demonstrated that the primary stimulus to remodeling in AF is atrial tachycardia 41,117 . Atrial tachycardia reduces AERP in a spatially heterogeneous fashion, promoting AF by reducing WL and increasing its heterogeneity 27 .…”