Bipolar Microsecond Pulses and Insulated Needle Electrodes for Reducing Muscle Contractions During Irreversible Electroporation

Objective: To minimize the effect of muscle contractions during irreversible electroporation (IRE), this paper attempts to research the ablation effect and muscle contractions by applying high-frequency IRE (H-FIRE) ablation to liver tissue in vivo. Methods: An insulated needle electrode was produced by painting an insulating coating on the outer surface of the needle electrode tip. A series of experiments were conducted using insulated needle electrodes and traditional needle electrodes to apply H-FIRE pulses and traditional monopolar IRE pulses to rabbit liver tissues. The finite element model of the rabbit liver tissue was established to determine the lethal thresholds of H-FIRE in liver tissues. Muscle contractions were measured by an accelerometer. Results: With increased constitutive pulse width and pulse voltage, the ablation area and muscle contraction strength are also increased, which can be used to optimize the ablation parameters of H-FIRE. Under the same pulse parameters, the ablation areas are similar for the two types of electrodes, and the ablation region has a clear boundary. H-FIRE and insulated needle electrodes can mitigate the extent of muscle contractions. The lethal thresholds of H-FIRE in rabbit liver tissues were determined. Conclusion: This paper describes the relationships between the ablation area, muscle contractions, and pulse parameters; the designed insulated needle electrodes can be used in IRE for reducing muscle contraction. Significance: The study provides guidance for treatment planning and reducing muscle contractions in the clinical application of H-FIRE.