Kos Bor, Mattison Lars, Ramirez David, Cindrič Helena, Sigg Daniel C, Iaizzo Paul A, Stewart Mark T, Miklavčič Damijan
Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.
Cardiac Ablation Solutions, Medtronic, Inc., Minneapolis, MN, United States.
Front Cardiovasc Med. 2023 Jun 23;10:1160231. doi: 10.3389/fcvm.2023.1160231. eCollection 2023.
Pulsed field ablation is an emerging modality for catheter-based cardiac ablation. The main mechanism of action is irreversible electroporation (IRE), a threshold-based phenomenon in which cells die after exposure to intense pulsed electric fields. Lethal electric field threshold for IRE is a tissue property that determines treatment feasibility and enables the development of new devices and therapeutic applications, but it is greatly dependent on the number of pulses and their duration.
In the study, lesions were generated by applying IRE in porcine and human left ventricles using a pair of parallel needle electrodes at different voltages (500-1500 V) and two different pulse waveforms: a proprietary biphasic waveform (Medtronic) and monophasic 48 × 100 μs pulses. The lethal electric field threshold, anisotropy ratio, and conductivity increase by electroporation were determined by numerical modeling, comparing the model outputs with segmented lesion images.
The median threshold was 535 V/cm in porcine (( = 51 lesions in = 6 hearts) and 416 V/cm in the human donor hearts (( = 21 lesions in = 3 hearts) for the biphasic waveform. The median threshold value was 368 V/cm in porcine hearts (( = 35 lesions in = 9 hearts) cm for 48 × 100 μs pulses.
The values obtained are compared with an extensive literature review of published lethal electric field thresholds in other tissues and were found to be lower than most other tissues, except for skeletal muscle. These findings, albeit preliminary, from a limited number of hearts suggest that treatments in humans with parameters optimized in pigs should result in equal or greater lesions.
脉冲场消融是一种新兴的基于导管的心脏消融方式。其主要作用机制是不可逆电穿孔（IRE），这是一种基于阈值的现象，细胞在暴露于强脉冲电场后会死亡。IRE的致死电场阈值是一种组织特性，它决定了治疗的可行性，并有助于开发新设备和治疗应用，但它很大程度上取决于脉冲数量及其持续时间。
在本研究中，使用一对平行针电极在猪和人类左心室中施加IRE，以不同电压（500 - 1500V）和两种不同的脉冲波形产生损伤：一种专有的双相波形（美敦力公司）和单相48×100μs脉冲。通过数值建模，将模型输出与分割后的损伤图像进行比较，确定致死电场阈值、各向异性比率和电穿孔引起的电导率增加。
对于双相波形，猪的中位阈值为535V/cm（6颗心脏中的51个损伤），人类供体心脏的中位阈值为416V/cm（3颗心脏中的21个损伤）。对于48×100μs脉冲，猪心脏的中位阈值为368V/cm（9颗心脏中的35个损伤）。
将获得的值与已发表的其他组织中致死电场阈值进行广泛的文献综述比较后发现，除骨骼肌外，这些值低于大多数其他组织。这些来自有限数量心脏的初步研究结果表明，在猪身上优化参数后用于人类治疗应能产生同等或更大的损伤。
