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Characterization of Radiofrequency Ablation Lesion Development Based on Simulated and Measured Intracardiac Electrograms

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Matthias W Keller, Steffen Schuler, Mathias Wilhelms, Gustavo Lenis, Gunnar Seemann, Claus Schmitt, Olaf D¨ossel, Armin Luik, Karlsruhe Institute of Technology (KIT), Institute of Biomedical Engineering
Volume 61, Issue 9, Page:2467-2478

September TBME-01498-2013_image_V2

Radiofrequency ablation (RFA) therapy is the gold standard in interventional treatment of many cardiac arrhythmias. A major obstacle are non transmural lesions, leading to recurrence of arrhythmias. Recent clinical studies have suggested intracardiac electrogram (EGM) criteria as a promising marker to evaluate lesion development. Seeking for a deeper understanding of underlying mechanisms, we established a simulation approach for acute RFA lesions. Ablation lesions were modeled by a passive necrotic core surrounded by a borderzone with properties of heated myocardium. Herein, conduction velocity and electrophysiological properties were altered. We simulated EGMs during RFA to study the relation between lesion formation and EGM changes using the bidomain model. Simulations were performed on a three dimensional setup including a geometrically detailed representation of the catheter with highly conductive electrodes. For validation, EGMs recorded during RFA procedures in five patients were analyzed and compared to simulation
results. Clinical data showed major changes in the distal unipolar EGM. During RFA, the negative peak amplitude decreased up to 104% and maximum negative deflection was up to 88% smaller at the end of the ablation sequence. These changes mainly occurred in the first 10 s after ablation onset. Simulated unipolar EGM reproduced the clinical changes, reaching up to 83% negative peak amplitude reduction and 80% decrease in maximum negative deflection for transmural lesions. In future work, the established model may enable the development of further EGM criteria for transmural lesions even for complex geometries in order to support clinical therapy.

Keywords: intracardiac electrograms, radiofrequency ablation (RFA), acute lesion model, bidomain model, simulation

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