Irreversible Electroporation for Focal Ablation at the Porta Hepatis

Abstract

Patients with chemotherapy-refractory liver metastases who are not candidates for surgery may be treated with focal ablation techniques with established survival benefits. Irreversible electroporation is the newest of these and has the putative advantages of a nonthermal action, preventing damage to adjacent biliary structures and bowel. This report describes the use of irreversible electroporation in a 61-year-old man with a solitary chemoresistant liver metastasis unsuitable for radiofrequency ablation as a result of its proximity to the porta hepatis. At 3 months, tumor size was decreased on computed tomography from 28 × 19 to 20 × 17 mm, representing stable disease according to the response evaluation criteria in solid tumors. This corresponded to a decrease in tumor volume size from 5.25 to 3.16 cm(3). There were no early or late complications. Chemoresistant liver metastases in the proximity of the porta hepatis that are considered to be too high a risk for conventional surgery or thermal ablation may be considered for treatment by the novel ablation technique of irreversible electroporation.

Radiological findings of porcine liver after electrochemotherapy with bleomycin

“…These findings were consistent with previously published histologic results: no thrombosis was identified at two and seven days after EP/ECT in healthy liver 28. This result was an expected finding considering ECT3, 4, 8, 11, 12, 13 and IRE17, 18, 19, 20, 21, 22 clinical studies, where electrodes were inserted in the vicinity of3, 4, 8, 11, 12, 13, 17, 18, 19, 20, 21, 22 or into major hepatic vessels 13. The absence of bleeding, even if needles are inserted deep into the hepatic parenchyma, is an important safety aspect of ECT due to the transient local hypoperfusion and possible electrocoagulation related to the high current density at the surface of needle electrodes 29, 35…”

“…Potentially hazardous electrode insertion into the lumen of major hepatic vessels has been reported in a study with percutaneous ECT of portal vein tumor thrombosis in patients with HCC 11. From ECT3, 4, 6, 7, 11, 12, 12, and IRE17, 18, 19, 20, 21, 22 studies, it is assumed that ECT of large hepatic vessels is safe, but this assumption has not yet been demonstrated with early radiologic examinations, which could reveal possible intra-abdominal hemorrhage or thrombus formation that could prove fatal for the patient.…”

Patterns of complications following intraoperative radiofrequency ablation for liver metastases

“…It is now commonly accepted that lesions situated close to the main biliary duct are contraindicated for ablation . The use of new ablative techniques, such as electroporation, in high‐risk areas merits further investigation, although recent results have been disappointing …”

Emerging minimally invasive procedures for focal treatment of organ-confined prostate cancer

“…The foundations of electroporation have been applied in clinical practice to facilitate the effect of chemotherapy drugs bleomycin and cisplatin [13,19]. The exact mechanism by which IRE induces cell death is currently unknown; however, initial results from both in vivo and in vitro IRE studies show promising results in destruction of various solid organ cancers [18,20,21]. Studies on focal IRE of canine prostates found that the procedure spared the animal's urethra, urethral sphincter, and neurovascular bundles from damage, a desired outcome in patients with low-grade disease who still wish to undergo definitive treatment [22].…”