Relationship between local atrial fibrillation interval and refractory period in the isolated canine atrium
Abstract
Atrial refractory periods and their spatial distribution are important determinants of atrial reentrant arrhythmias. The objective of this study was to demonstrate a correlation between the local atrial fibrillation interval (AFI) and local effective refractory period (ERP). To measure the local ERP and local AFI under stable conditions without hemodynamic, autonomic, or reflex influences, isolated perfused canine whole atria were used (n = 8). The isolated atria were mounted on two endocardial electrodes. Bipolar electrograms were simultaneously recorded from 253 endocardial sites, and 16 to 20 randomly distributed electrodes were used to measure the local ERP by the extrastimulus technique. In all studies, several episodes of AF were induced by a single extrastimulus. The ERP and minimum AFI converged with increasing duration of AF. The convergence was more rapid if the total duration of AF analyzed came from multiple episodes of AF. The correlation coefficient between the local ERP and minimum local AFI was .92 (n = 119, P < .001). The minimum AFI was used to construct AFI distribution maps at all 253 sites. Activation block during premature stimulation correlated with regions of long AFI. The minimum local AFI measured from...Continue Reading
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