Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia and catheter mapping has been proved to be an effective approach for detecting AF drivers to be targeted by ablation. Among drivers, the so-called rotors have gained the most attention: their identification and spatial location could help to understand which patient-specific mechanisms are acting, and thus to guide the ablation execution. Since rotor detection by multi-electrode catheters may be influenced by several structural parameters including inter-electrode spacing, catheter coverage, and endocardium-catheter distance, in this study we proposed a tool for testing the ability of different catheter shapes to detect rotors in different conditions. An approach based on the solution of the monodomain equations coupled with a modified Courtemanche ionic atrial model, that considers an electrical remodeling, was applied to simulate spiral wave dynamics on a 2D model for 7.75 s. The developed framework allowed the acquisition of unipolar signals at 2 KHz. Two high-density multipolar catheters were simulated (Advisor™ HD Grid and PentaRay®) and placed in a 2D region in which the simulated spiral wave persists longer. The configuration of the catheters was then modified by changing the number of electrodes, inter-electrodes distance, position, and atrial-wall distance for assessing how they would affect the rotor detection. In contact with the wall and at 1 mm distance from it, all the configurations detected the rotor correctly, irrespective of geometry, coverage, and inter-electrode distance. In the HDGrid-like geometry, the increase of the inter-electrode distance from 3 to 6 mm caused rotor detection failure at 2 mm distance from the LA wall. In the PentaRay-like configuration, regardless of inter-electrode distance, rotor detection failed at 3 mm endocardium-catheter distance. The asymmetry of this catheter resulted in rotation-dependent rotor detection. To conclude, the computational framework we developed is based on realistic catheter shapes designed with parameter configurations which resemble clinical settings. Results showed it is well suited to investigate how mapping catheter geometry and location affect AF driver detection, therefore it is a reliable tool to design and test new mapping catheters.
Highlights
Mechanisms responsible for atrial fibrillation (AF) initiation and maintenance are still largely debated, and different hypotheses have been formulated
Since rotor detection by multi-electrode catheters may be influenced by several parameters including inter-electrode spacing, catheter coverage, and endocardium-catheter distance, in this work: (i) we used computer simulations to overcome clinical limitations in studying these factors influencing the precision of multi-electrode mapping; and (ii) we developed a tool which allows the testing of different catheters shapes in different conditions and their behavior in detecting a synthetic rotor
In our model we considered the atrial tissue as a two-dimensional grid of cells of size 5 × 5 cm with a distance between cells of 0.25 mm, using the monodomain approach with a fixed time step of 10μs, Neumann boundary conditions, and a modified Courtemanche et al (1998). action potential (AP) model which accounts for AF related ionic remodeling
Summary
Mechanisms responsible for atrial fibrillation (AF) initiation and maintenance are still largely debated, and different hypotheses have been formulated. Two main hypotheses so far prevail: local drivers and multiwavelet reentries. The former proposes a stationary driver generating waves that propagate to the atria passively and in a nonuniform way, constituting “fibrillatory conduction.”. The latter hypothesis is related to self-sustaining, moving functional reentrant circuits without any stable driver. Several combinations of such mechanisms from drivers to multiwavelets in time have been subsequently proposed. The “rotors theory,” proposed by Narayan et al (2012), hypothesized that some fairly stable electrical rotors can be traced and targeted on a patient-specificbased approach for AF ablation
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