Abstract

-Human atrial fibrillation (AF) can terminate after ablating localized regions, that supports the existence of localized rotors (spiral waves) or focal drivers. However, it is unclear why ablation near a spiral wave tip would terminate AF and not anchor reentry. We addressed this question by analyzing competing mechanisms for AF termination in numerical simulations, referenced to clinical observations.-Spiral wave reentry was simulated in monodomain 2D myocyte sheets using clinically realistic rate-dependent values for repolarization and conduction. Heterogeneous models were created by introduction of parameterized variations in tissue excitability. Ablation lesions were applied as non-conducting circular regions. Computational models confirmed localized ablation may anchor spiral wave reentry, producing organized tachycardias. Several mechanisms also explained termination of AF to sinus rhythm. First, lesions may create an excitable gap vulnerable to invasion by fibrillatory waves. Second, ablation of rotors in regions of low-excitability (from remodeling) produced reentry in more excitable tissue allowing collision of wave-front and back. Conversely, ablation of rotors in high-excitability regions migrated spiral waves to less excitable tissue, where they detached to collide with non-conducting boundaries. Third, ablation may connect rotors to non-conducting anatomic orifices. Fourth, reentry through slow conducting channels may terminate if ablation closes these channels.-Limited ablation can terminate AF by several mechanisms. These data shed light on how clinical AF may be sustained in patients' atria, emphasizing heterogeneities in tissue excitability, slow-conducting channels and obstacles that are increasingly detectable in patients and should be the focus of future translational studies.

View details for DOI 10.1161/CIRCEP.115.002956

View details for PubMedID 26359479