New insights on atrial fibrillation mechanisms through the analysis of structural and electrical features

Atrial fibrillation is the most common type of arrhythmia but its maintaining mechanisms remain elusive. Radiofrequency catheter ablation is a non-pharmacological therapy that aims to restore sinus rhythm ablating tissue that facilitates atrial fibrillation perpetuation and is more effective than medications. Neverthless, rigorous monitoring after the ablation procedures showed atrial fibrillation recurrence in about 40\% to 60\% of cases for one procedure and in about 70\% of cases for three or more procedures. It is well known that the hallmarks of the structural changes during atrial fibrillation are the fibrosis tissue generation and left atrium dilatation. According to recent studies, the success rate of the ablation procedure depends on the atrial fibrotic tissue extent on the atrial wall. Other studies ascribe the ablation failure to left atrium enlargement occurring during the arrhythmia. A recent study showed the presence of electrical rotors whose ablation may improve the outocome of the ablation procedure. Other studies did not confirm these results. The aim of this thesis is to provide computational approaches to better investigate the existence of the electrical rotors and the role of the left atrium structural alterations as potential primary mechanisms sustaining atrial fibrillation. The thesis is composed by four chapters. The first chapter introduces the atrial fibrillation and describes in details the electrical rotor and the structural remodeling phenomena. The second chapter regards the structural characterization of the left atrium through the development of a fully-automated approach for 3D left atrium fibrosis patient specific model construction and left atrium volume estimation. The third chapter regards the electrical characterization of the left atrium throught the development of an independent approach for the rotor localization on 3D left atrium surface. Finally in the fourth chapter some conclusive remarks are presented with possible future developments of the presented work.