How a Topological Mindset May Offer Extra Control During Mapping and Ablation of Left-Sided Reentrant Atrial Tachycardia.

Background: Reentry (macro or localized) is historically described as multiple pathways that are separated by barriers (either anatomic or functional) and involve active and passive loops (identified by electro-anatomic and entrainment mapping, EAM/ETM). Some reentrant atrial tachycardia (AT) cases are characterized by challenging activation patterns and unexpected ablation responses. A recent translational study, focusing on topology (TOP) and the role of boundaries, suggests that thinking topology within EAM/ETM might offer extra control during mapping and ablation of reentrant AT.

DGM-TOP: automatic identification of the critical boundaries in atrial tachycardia.

Introduction: In the latest research on topology in cardiac arrhythmia, it was demonstrated through a fundamental mathematical principle called the index theorem that reentry based atrial tachycardias (AT) are maintained by pairs of counter-rotating waves that are either complete or near-complete rotations. Each wave is centered around a different anatomical object that exhibits a non-zero index/topological charge, called a critical boundary. Interconnecting both critical boundaries with an ablation line terminates the tachycardia.

Detection of regular rotational activity during cardiac arrhythmia using the Helmholtz decomposition for directed graphs.

We introduce DGM-CURL, a novel method to detect reentry in cardiac activation based on the Helmholtz Decomposition for directed graphs. DGM-CURL is an extension to our open-source diagnostic framework Directed Graph Mapping (DGM). We compare DGM-CURL to two existing methods, Phase Mapping (PM), and Directed Cycle Search (DGM-CYCLE).

Directed Graph Mapping exceeds Phase Mapping for the detection of simulated 2D meandering rotors in fibrotic tissue with added noise.

Cardiac arrhythmias such as atrial fibrillation (AF) are recognised to be associated with re-entry or rotors. A rotor is a wave of excitation in the cardiac tissue that wraps around its refractory tail, causing faster-than-normal periodic excitation. The detection of rotor centres is of crucial importance in guiding ablation strategies for the treatment of arrhythmia.

Directed graph mapping shows rotors maintain non-terminating and focal sources maintain self-terminating Torsade de Pointes in canine model.

Torsade de Pointes is a polymorphic ventricular tachycardia which is as yet incompletely understood. While the onset of a TdP episode is generally accepted to be caused by triggered activity, the mechanisms for the perpetuation is still under debate. In this study, we analysed data from 54 TdP episodes divided over 5 dogs (4 female, 1 male) with chronic atrioventricular block.

DG-Mapping: a novel software package for the analysis of any type of reentry and focal activation of simulated, experimental or clinical data of cardiac arrhythmia.

In this work, we present the release of a novel easy to use software package called DGM or Directed-Graph-Mapping. DGM can automatically analyze any type of arrhythmia to find reentry or focal sources if the measurements are synchronized in time. Currently, DGM requires the local activation times (LAT) and the spatial coordinates of the measured electrodes.