Breakthrough Wave Detection in a 3D Computer Model of Atrial Endo-Epicardial Dissociation

Experimental and clinical mapping of atrial fibrillation has revealed the occurrence of breakthrough activation patterns. These focal waves have been associated with endo-epicardial (endo-epi) dissociation and three-dimensional anatomical structures. To assess breakthrough detection techniques in computer models of atrial fibrillation, we created a 3D cubic-mesh atrial model with locally controllable endo-epi dissociation. In this model, epi and endo layers were electrically coupled only at randomly-distributed discrete connection sites. Eighteen endo-epi connection patterns were generated. Dedicated finite-difference numerical methods were developed to handle these discontinuities in conduction. These configurations were designed to generate breakthroughs at predictable locations. We developed a breakthrough detection algorithm based on full-resolution activation maps of both the epi- and endocardial surfaces. Wave tracking was used to calculate the lifespan of breakthroughs. Non-propagating passive responses and breakthroughs with too short lifespan were eliminated. The approach was manually and automatically validated in 48 episodes of fibrillation in models with varying number of endo-epi connections.