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Povzetek: Background Pulsed field ablation (PFA) is a novel cardiac ablation modality with an increasing clinical acceptance in treatment of atrial fibrillation due to its clinical efficacy and excellent safety profile. However, intraprocedural guidance for PFA to ensure durable pulmonary vein isolation (PVI) is lacking. Objective We quantified changes in intracardiac electrograms (iEGMs) following PFA and radiofrequency ablation (RFA) and investigated their applicability for prediction of lesion transmurality. Methods We induced 38 atrial lesions using PFA or RFA in 5 swine and monitored iEGMs continuously for up to 30 minutes postablation. The most characteristic changes in iEGMs were quantified after the decomposition using discrete wavelet transform, which allowed us to analyze the effects in separate frequency bandwidths. Results After the ablation, we observed a reduction of bipolar iEGM amplitude (for PFA and RFA) and an increase in unipolar iEGM amplitude (predominantly for PFA). These changes were due to 2 mechanisms with different frequency content. The low-frequency content of unipolar iEGMs (1–16 Hz) further enabled us to discriminate between transmural and nontransmural lesions in the case of PFA. The rate of reduction of initially increased current-of-injury effect reflected in the low-frequency content of unipolar iEGMs within the first few minutes postablation was significantly higher and more pronounced for nontransmural lesions. Conclusion This study shows that unipolar iEGMs can be used to differentiate between transmural and nontransmural atrial lesions within minutes after PFA in a porcine model, with implications for development of intraprocedural guidance of PFA procedures.
Ključne besede: pulsed field ablation, atria porcine model, intracardiac electrograms, bipolar vs unipolar iEGM, frequency analysis, discrete wavelet transform, current of injury, lesion transmurality
Objavljeno v DiRROS: 14.04.2026; Ogledov: 151; Prenosov: 98
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Povzetek: BACKGROUND: Various pulsed field ablation (PFA) parameters have been proposed to improve lesion depth. This study evaluated a modified unipolar return PFA system to create deep lesions in healthy and infarcted ventricular myocardia. METHODS: Numerical modeling was used to compare a modified unipolar return PFA system configuration with a conventional unipolar return (skin patch). We then performed ablation in 14 swine (5 with chronic myocardial infarction and 9 healthy). PFA lesions were created in the left ventricle using a focal catheter (4-mm tip) with a return electrode positioned in the inferior vena cava (biphasic, microsecond pulses of 1300 and 1500 V, 1–16 trains). Electroanatomical mapping guided ablation and lesion localization on magnetic resonance imaging were performed 48 hours post-ablation in the infarcted group and at 1 day, 7 days, and 6 weeks post-ablation in the healthy group. RESULTS: Numerical modeling demonstrated that the modified unipolar return PFA system produced deeper lesions with reduced variability compared with the skin patch. In healthy pigs (n=35 lesions), depths of 6.8±1.8 mm and widths of 11.5±4.7 mm were achieved with 8 pulse trains. Depths of 8.2±2.8 mm and widths of 14.0±4.7 mm were achieved with 16 trains. The maximum lesion depths were 8.8 and 11.6 mm for 8 and 16 trains, respectively. In the infarcted cohort (n=22 lesions), all lesions applied to scar tissue penetrated through fibrotic regions, with epicardial involvement observed in 57% of lesions. CONCLUSIONS: The modified unipolar return PFA system effectively creates large lesions and can achieve transmurality in healthy and infarcted animals. Compared with conventional unipolar, it may offer greater lesion depth, width, and consistency. GRAPHIC ABSTRACT: A graphic abstract is available for this article.
Ključne besede: atrial fibrillation, catheter ablation, heart ventricles, pulmonary veins, tachycardia ventricular
Objavljeno v DiRROS: 11.12.2025; Ogledov: 331; Prenosov: 234
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Povzetek: Delivery of electrical energy for sensing or therapeutic purposes often involves electrochemical phenomena at the electrode-electrolyte solution interface. Release of gaseous bubbles that accompanies delivery of pulsed electric fields to tissues in applications such as electrochemotherapy of tumours and irreversible electroporation or pulsed field ablation in cardiac electrophysiology needs to be understood and characterized. We present an in vitro study using pulsed field delivery into saline, employing multiple different treatment protocols, two electrode geometries (pair of needles and a modified RF catheter), and two imaging systems to elucidate the complex relationship between the electrical treatment protocol, temperature changes at and around the electrodes, and gas release due to pulse delivery. Our primary objective was to identify the key parameters responsible for bubble formation and to highlight the importance of the treatment parameters and their interplay – ranging from the temperature to appropriate choice of electrode geometry, and, most importantly, to the choice of the treatment protocol. We found that bubbles originating from electrochemical reactions are more prevalent in monophasic pulsing protocols, whereas in high frequency biphasic pulsing protocols the bubbles are mainly caused by boiling of the medium. Degassing of liquid due to lower solubility of gasses at elevated temperatures does seems to play a role, though a minor one. We also observed that bubbles caused by boiling collapse very rapidly, whereas electrochemically produced bubbles or those produced through degassing appear to have longer lifetimes. Therefore, the treatment protocols most suited to minimizing gas release are biphasic trains of short (▫$\mu$▫s) pulses with a significant inter-pulse delay (i.e. low duty cycle) to prevent excessive heating. Moreover, electrodes must be designed to avoid high local current densities. Our findings have broad implications extending from lab-on-achip cell electroporation devices to intracorporeal pulsed field applications in the cardiovascular system, particularly pulsed field ablation procedures.
Ključne besede: pulsed field ablation, gas release, electrochemistry, Joule heating, water phase transition
Objavljeno v DiRROS: 10.04.2025; Ogledov: 869; Prenosov: 528
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Ključne besede: electroporation, pulsed electric field treatment, damage-associated molecular pattern molecules, immunogenic cell death, electrochemotherapy
Objavljeno v DiRROS: 15.07.2024; Ogledov: 1068; Prenosov: 818
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Ključne besede: electroporation, electrochemotherapy, high-frequency bipolar pulses, cisplatin, cell survival, drug uptake
Objavljeno v DiRROS: 09.07.2024; Ogledov: 1196; Prenosov: 679
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