Influence of atrial dilatation in the generation of re-entries caused by ectopic activity in the left atrium

Structural remodeling plays an important role in the genesis and maintenance of atrial arrhythmias. In this work, the influence of atrial dilatation on the generation of reentrant activity trigger by an ectopic beat applied at different locations of the left atrium was studied. We have developed two 3D models of human atria: a model with electrical remodeling only, and a model with electrical and structural remodeling (atrial dilatation). Both models include the Nygren atrial cell model and realistic fiber orientation. When an ectopic beat is applied in the middle of the free wall of the left atrium, a reentry was not generated; however, in dilated left atrium, reentrant activity was generated. For ectopic beats applied between pulmonary veins, the vulnerable window to reentry was higher in dilated atria than in normal atria. This study shows the important influence of atrial dilatation on the vulnerability to reentries, triggered by ectopic activity.