温度开环和闭环反馈在高压脉冲电场消融中的对照研究

Comparison of temperature open-loop and closed-loop feedbacks in high-voltage pulsed electric field ablation

目的:对比温度开环和闭环反馈在高压脉冲电场消融中的区别。方法:温度开环组应用高压方波脉冲发生器以场强1.5 kV/cm、频率1 Hz、脉宽100μs、脉冲数20个的条件对细胞悬液、3D细胞模型和离体猪肝组织3种不同负载施加高压脉冲电场。闭环组在相同脉冲条件下增加温度闭环算法对微控制器及温度传感器编程控制脉冲发放。分别从电场消融后的电极温度、细胞悬液电导率和细胞死亡率,3D细胞模型消融截面积以及猪肝组织消融区病理特点进行定量比较和定性分析。结果:消融后开环组电极温度、细胞悬液电导率、细胞死亡率和3D细胞模型消融截面积分别为(53.2±5.5)℃、(1.43±0.03)S/m、(86.8±5.5)%和(0.46±0.15)cm^(2),均高于闭环组对应的(38.5±1.6)℃、(1.21±0.02)S/m、(73.6±10.2)%和(0.37±0.08)cm^(2),差异均有统计学意义(P<0.05);开环组消融区猪肝组织H-E染色可见热损伤导致的凝固性坏死区,闭环组表现为肝血窦增宽、细胞质脱水丢失和核聚集。结论:该实验条件下,温度开环和闭环反馈高压脉冲电场消融存在差异。传统温度开环高压脉冲电场消融效果略强于温度闭环,这可能与电导率增加和热效应介导的电场杀伤效应增强有关。温度闭环反馈能避免热损伤效应,实现真正意义上的非热性消融。

Objective To compare the differences between temperature open-loop and closed-loop feedbacks in high-voltage pulsed electric field ablation.Methods Three different loads,namely cell suspension,3D cell model and swine liver tissue ex vivo both in temperature open-loop group and temperature closed-loop group were exposed to high-voltage square-wave pulsed electric field with a field strength of 1.5 kV/cm,frequency of 1 Hz,pulse width of 100μs and pulse number of 20.Moreover,a temperature closed-loop algorithm was added in closed-loop group to control pulse delivery of temperature sensor to the microcontroller.Electrode temperature,cell suspension conductivity and cell death rate,3D cell model ablation area and pathological characteristics of swine liver tissue ablation zone after electric field ablation were quantitatively compared and qualitatively analyzed.Results The electrode temperature,cell suspension conductivity,cell death rate and 3D cellmodel ablation area in open-loop group after ablationwere(53.2±5.5)℃,(1.43±0.03)S/m,(86.8±5.5)%and(0.46±0.15)cm^(2),respectively,higher than(38.5±1.6)℃,(1.21±0.02)S/m,(73.6±10.2)%and(0.37±0.08)cm^(2) in closed-loop group,and the differences were statistically significant(all P<0.05).Through hematoxylin-eosin staining,coagulation necrosis caused by thermal injury was found in swine liver tissue ablation zone in open-loop group,while widening in hepatic sinusoids,cytoplasmic dehydration and loss,and nuclear accumulation were observed in closed-loop group.Conclusion Under the experimental conditions,there are differences between temperature open-loop and closed-loop feedbacks groups.The traditional temperature open-loop high-voltage pulsed electric field has a slightly stronger ablation effect than temperature closed-loop ablation,which may be related to the increase in electrical conductivity and the enhancement of the lethal effects of electric field mediated by thermal effects.Temperature closed-loop feedback can avoid thermal damage effects and achieve real non-thermal ablation.