Abstract
Background
Radiofrequency ablation (RFA) is a common approach to treat cardiac arrhythmias. During this intervention, numerous strategies are applied to indirectly estimate lesion formation. However, the assessment of the spatial extent of these acute injuries needs to be improved in order to create well-defined and durable ablation lesions.
Methods
We investigated the electrophysiological characteristics of rat atrial myocardium during an ex vivo RFA procedure with fluorescence-optical and electrical mapping. By analyzing optical data, the temporal growth of punctiform ablation lesions was reconstructed after stepwise RFA sequences. Unipolar electrograms (EGMs) were simultaneously recorded by a multielectrode array (MEA) before and after each RFA sequence. Based on the optical results, we searched for electrical features to delineate these lesions from healthy myocardium.
Results
Several unipolar EGM parameters were monotonically decreasing when distances between the electrode and lesion boundary were smaller than 2 mm. The negative component of the unipolar EGM [negative peak amplitude (Aneg)] vanished for distances lesser than 0.4 mm to the lesion boundary. Median peak-to-peak amplitude (Vpp) was decreased by 75% compared to baseline.
Conclusion
Aneg and Vpp are excellent parameters to discriminate the growing lesion area from healthy myocardium. The experimental setup opens new opportunities to investigate EGM characteristics of more complex ablation lesions.
Acknowledgments
We would like to thank Ramona Modery and Dirk Falkenberg for their support during the ex vivo experiment. Furthermore, special thanks go to Dr. Callum Zgierski-Johnston for his technical support (Bioinstrumentation Group, Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Medical Department of the Albert-Ludwigs University Freiburg).
Author contributions: S.P. conceived and designed the experiments in collaboration with O.D. S.P. performed the experiments. S.P., G.S. and A.L. analyzed, interpreted and evaluated the experimental data. S.P., G.S. and A.L. drafted the manuscript. O.D. critically revised the manuscript. All authors have approved the final version of the manuscript.
Research funding: This project was supported by the German Research Foundation (Funder Id: http://dx.doi.org/10.13039/501100001659, DFG grant DO 637/20-1) and CRC 1173. S. Pollnow received a scholarship from the Karlsruhe School of Optics and Photonics (KSOP).
Conflict of interest: Authors state no conflict of interest.
Informed consent: Informed consent is not applicable.
Ethical approval: The conducted research is not related to either human or animal use.
Disclosure: Part of this study was published before as a thesis [42].
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Supplementary Material
The online version of this article offers supplementary material (https://doi.org/10.1515/bmt-2019-0013).
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