Session P84.1

Effect of the Ectopic Beat Location on Vulnerability to Reentries in a Three-Dimensional Realistic Model of Human Atrium

C Tobón, C Ruiz, E Heidenreich, F Hornero, J Saíz*

Universidad Politécnica de Valencia
Valencia, Spain

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice. AF induces changes in atrial properties (atrial remodelling) that helps to perpetuate it. Recent studies have shown that an ectopic activity in the pulmonary veins can trigger reentrant mechanisms and lead to AF in the presence of a vulnerable substrate (remodelling tissue). However, the influence of ectopic focus situation on the likelihood of triggering re-entries and AF is not well known. In this work we study the effect of the ectopic beats location on vulnerability to reentries in a remodelling tissue. To carry out the study, the effects of electrical remodelling were incorporated in an atrial cell model and integrated in a realistic three-dimensional (3D) model of human atrium. An ectopic beat was applied at four different locations in the left atrium: posterior wall, appendage, and ostium of the left and right pulmonary veins. Pseudo-unipolar electrograms in different regions and spectral analysis to the signals obtained were calculated. The simulations show that electrical remodelling favours the generation of reentrant mechanisms initiated by ectopic activity and the location of the ectopic beat affects the length of the vulnerable window. When the ectopic beat was applied at the left and right pulmonary veins-atrial junction, the vulnerable windows were 16 ms and 2 ms, respectively. However, when the ectopic beat was applied at the posterior wall and appendage of the left atrium, reentry was not observed. The wavefronts collided with the refractory tail. An episode of 10 seconds of AF simulated showed electrograms with left-to-right atrial DF gradient (0.4 Hz), with dominant frequency (DF) highest at the posterior wall of the left atrium (7.9 Hz) and lowest in the right appendage (7.0 Hz). However, during sinus activity, left-to-right atrial DF gradient was not observed, with a DF of 3.4 Hz in all measure points. In conclusion, this work shows the great influence of the ectopic activity location on the re-entrant activity and the utility of biophysical modelling as a useful tool for understanding the underlying mechanisms of AF.

(Abstract Control Number: 95)