The three-dimensional substrate of atrial fibrillation in the goat : a simultaneous endo-epicardial mapping study

Atrial fibrillation (AF) is the most common arrhythmia in humans and Maastricht is a reference center for mapping of AF. Mapping is a technique to visualize the electrical activity of the atrial muscle. In earlier studies this was performed solely on the outer (epicardial) surface of the atrium. In this thesis we describe a novel technique and findings of simultaneous, endo-epicardial mapping. We could show that, while electrical activity during normal rhythm is synchronous at the inside and the outside of the atrium, it is getting increasingly dissociated if AF is present for a longer time (weeks to months). Along with this we could demonstrate that so called breakthrough events, that represent focal activations in two-dimensional mapping, are explainable by transmurally propagated electrical activity from the opposing side of the atrial wall in most cases. These findings help to understand what makes AF increasingly stable and harder to treat over time.