Epicardial delivery of diversified pulsed field potentials in animal model

article in a collection out of WoS and Scopus

English

Ablation of arrhythmias is based on thermal energy methods, radiofrequency and cryoablation. Despite high success rate, thermal character limits lesion formation control and may affect esophagus, phrenic nerve, and lungs. Non thermal irreversible electroporation (IRE) is inducing apoptotic cell death, is tissue-specific and effective. The comparison between AC/DC energy sources has not been systematically approached, clinically relevant parameters are yet to be validated. Methods: 12 farm pigs (female, 6m old, 45-55kg) underwent thoracotomy and epicardial IRE shock delivery. Square DC/AC pulse generators were connected to planar stainless-steel electrode (6x6mm) in a suction cup for tissue adherence, versus reference patch on the animal back (ca. 40cm from heart). High voltage AC/DC pulses (10 and 2 animals, 100 µs, 60 pulses, each set of 400, 600 and 800 V) were delivered in myorelaxation, at target frequency 80/min. in 3x3 grid application on left ventricle and 2*2 grid on left atrium, marked by surgical stitches. Maximum voltage was limited by 15 A compliance current. Surface ECG and arterial blood pressure were monitored. Twitching was monitored in rib muscles and limbs at different grades, less evidently for AC shocks. DC pulses delivered in on endogenous T-wave resulted in ventricular fibrillation requiring defibrillation. 1.5 T cardiac MR for lesion maturation was done 14, 30 and 60 days post procedure. Not by AC, but DC pulses late gadolinium enhancement was present in relevant epicardial area, separate lesions were not distinguished and pericardial effusion was present on mid-term, not at final time point. Contractility was fully preserved in all cases. Before euthanasia, 6 endocardial voltage maps were performed using 3D EAM CARTO 3, three presented normal voltage map, three showed several low voltage areas on anterior/lateral wall without changes typical for scar (fractionated, late potentials). During gross inspection, no injury to lung or esophagus was observed. Pericardium showed adhesions due to surgical access and manipulation. Explanted hearts were relaxed by cardioplegic solution, fixed in 4% formaldehyde, ex vivo scanned by 9.4 T MRI. Clear fibrotic changes, were not present, just occasional shallow alterations in the MRI. Haematoxylin/eosin staining revealed a unique cuneiform fibrosis on epicardial surface of left ventricle. Conclusions: DC and AC epicardial applications did not impose transmural lesions in presented setting. Endocardial maps and cardiac MRI did not show clear endocardial scarring within 90 days. Histology didn´t proof consistent lesion formation, possibly due to long distance between indifferent and active electrode. There was no damage to adjacent structures. When not appropriately synchronized, DC pulses induced ventricular fibrillation, effectively avoidable by selective pulse application. AC pulses didn´t cause significant muscle twitching, while DC caused twitching even after standard myorelaxation.

irreversible electroporation; catheter ablation, animal models; epicardial intervention

PESL, M., CALUORI, G., WOLF, J., CERVINKA, D., NOVOTNA, V.; PILER, P., NICOVSKY, J., CRHA, M., ZAMPACHOVA, V., DRAZANOVA, E., STAREK, Z.

2. 9. 2019

978-2-913923-38-6

3rd World Congress on Electroporation and Pulsed Electric Fields in Biology, Medicine, and Food and Environmental Technologies

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