A Computational Framework to Benchmark Basket Catheter Guided Ablation in Atrial Fibrillation

Abstract

Catheter ablation is a curative therapeutic approach for atrial fibrillation (AF). Ablation of rotational sources based on basket catheter measurements has been proposed as a promising approach in patients with persistent AF to complement pulmonary vein isolation. However, clinically reported success rates are equivocal calling for a mechanistic investigation under controlled conditions. We present a computational framework to benchmark ablation strategies considering the whole cycle from excitation propagation to electrogram acquisition and processing to virtual therapy. Fibrillation was induced in a patient-specific 3D volumetric model of the left atrium, which was homogeneously remodeled to sustain reentry. The resulting extracellular potential field was sampled using models of grid catheters as well as realistically deformed basket catheters considering the specific atrial anatomy. The virtual electrograms were processed to compute phase singularity density maps to target rotor tips with up to three circular ablations. Stable rotors were successfully induced in different regions of the homogeneously remodeled atrium showing that rotors are not constrained to unique anatomical structures or locations. Density maps of rotor tip trajectories correctly identified and located the rotors (deviation < 10 mm) based on catheter recordings only for sufficient resolution (inter-electrode distance ≤3 mm) and proximity to the wall (≤10 mm). Targeting rotor sites with ablation did not stop reentries in the homogeneously remodeled atria independent from lesion size (1–7 mm radius), from linearly connecting lesions with anatomical obstacles, and from the number of rotors targeted sequentially (≤3). Our results show that phase maps derived from intracardiac electrograms can be a powerful tool to map atrial activation patterns, yet they can also be misleading due to inaccurate localization of the rotor tip depending on electrode resolution and distance to the wall. This should be considered to avoid ablating regions that are in fact free of rotor sources of AF. In our experience, ablation of rotor sites was not successful to stop fibrillation. Our comprehensive simulation framework provides the means to holistically benchmark ablation strategies in silico under consideration of all steps involved in electrogram-based therapy and, in future, could be used to study more heterogeneously remodeled disease states as well.

TheopenCARPSimulation Environment for Cardiac Electrophysiology

“…A commercial license can be requested. Interoperability: openCARP builds on two decades of CEP modeling experience gained with its proprietary predecessors, CARP [16] and acCELLerate [17], with a stable user base about 130 registered users. The predecessor software packages have been extensively used by several CEP modeling groups and led to >250 peer-reviewed journal publications, covering the full range of modeling issues including numerical methods [71], anatomical modeling and model functionalization [48, 72] as well as a broad range of applications such as formation and maintenance of arrhythmias [73,74], EP therapies [75,76], diagnostic [77, 78] and therapeutic applications [79, 80]. The openCARP simulator has been built from scratch in terms of code, but the user interface is consistent with previous proprietary versions of CARP [16] to facilitate re-use of a large number of existing experiments.…”

Patient-Specific Identification of Atrial Flutter Vulnerability–A Computational Approach to Reveal Latent Reentry Pathways

“…Thus, no substrate information regarding fibrosis, zones of slow conduction or the degree of electrophysiological remodeling is considered. Recently, Alessandrini et al (2018) presented an in silico framework to holistically consider the entire cycle from excitation propagation, catheter deformation, electrogram acquisition and processing to virtual ablation. McDowell et al (2015) published a proof-of-concept how computational modeling can predict ablation sites terminating rotors driving AF in personalized models including fibrosis distribution.…”

Novel mapping techniques for rotor core detection using simulated intracardiac electrograms

“…In the previous study by Alessandrini et al, 11 it has been shown that the electrode spacing influences the accuracy of the rotor localization. For instance, they demonstrated that for a grid catheter model, 3 mm interelectrode spacing produced rotor localization with minimized errors.…”

“…In silico studies suggested that rotors are not constrained to unique anatomical structures or locations in the atria. 11 In another recent study, it has been shown that a conduction block extending from the core of the rotor to one of the unexcited boundaries of the rotational site can completely terminate AF. 12 Therefore, there is a need to develop more sophisticated approaches for better identification of the core of rotors, especially based on electrogram (EGM) recordings.…”