Cardiac synchronization and arrhythmia during irreversible electroporation

Advances in irreversible electroporation for prostate cancer

Irreversible electroporation is a nonthermal ablation technique that uses a high-voltage electric current to create nanosized pores in the cell membrane of a malignant tumor, thus resulting in cell death. In recent years, an increasing number of clinical studies have shown that irreversible electroporation is a safe and effective treatment for prostate cancer. We describe the progress of irreversible electroporation in prostate cancer in recent years in terms of its mechanism of action, clinical studies, advantages and disadvantages and summarize the gaps in existing studies and directions for future research.

Irreversible electroporation for prostate cancer: another promising focal therapy

Radical treatment for prostate cancer is associated with significant morbidity. Percutaneous image-guided irreversible electroporation is a non-thermal ablative technique that has emerged as a valuable option. This study describes the case of a patient with prostate cancer who was successfully treated using irreversible electroporation. We report the case of a 72-year-old male patient who presented with elevated PSA (4.0ng/mL) during routine testing. Multiparametric magnetic resonance imaging of the prostate revealed a 0.8 cm lesion in the posterolateral aspect of the right midgland with marked hypointensity on ADC (ACR PI-RADS 4). The transperineal prostate revealed acinar adenocarcinoma (Gleason Score 3+3=6; International Society of Urological Pathology=1). Serum PSA levels reduced to 1.04ng/mL 32 days after the procedure and remained within normal limits (1.26ng/mL) after 349 days. Follow-up imaging performed 90 days later with prostate-specific membrane antigen PET/MRI showed size reduction, retraction, and diffuse hypointensity in the peripheral zone of the right prostate lobe, with no increase in prostate-specific membrane antigen uptake. Magnetic resonance imaging found no suspicious lesions 367 days after irreversible electroporation. At the final clinical follow-up at 390 days, the patient was asymptomatic. Our findings illustrate the potential of irreversible electroporation as a possible alternative treatment for prostate cancer.

Oncologic Outcomes after Percutaneous Ablation for Colorectal Liver Metastases: An Updated Comprehensive Review

Colorectal cancer is a major cause of cancer-related mortality, with liver metastases occurring in over a third of patients, and is correlated with poor prognosis. Despite surgical resection being the primary treatment option, only about 20% of patients qualify for surgery. Current guidelines recommend thermal ablation either alone or combined with surgery to treat limited hepatic metastases, provided that all visible disease can be effectively eradicated. Several ablation modalities, including radiofrequency ablation, microwave ablation, cryoablation, irreversible electroporation and histotripsy, are part of the percutaneous ablation armamentarium. Thermal ablation, including radiofrequency, microwave ablation and cryoablation, can offer local tumor control rates comparable to limited resection for selected tumors that can be ablated with margins. This review aims to encapsulate the current clinical evidence regarding the efficacy and oncologic outcomes after percutaneous ablation for the treatment of colorectal liver metastatic disease.

Irreversible Electroporation for Liver Metastases from Colorectal Cancer: A Systematic Review

BACKGROUND

Irreversible electroporation (IRE) is a non-thermal form of ablation based on the delivery of pulsed electrical fields. It has been used to treat liver lesions, particularly those in proximity to major hepatic vasculature. The role of this technique in the portfolio of treatments for colorectal hepatic metastases has not been clearly defined. This study undertakes a systematic review of IRE for treatment of colorectal hepatic metastases.

METHODS

The study protocol was registered with the PROSPERO register of systematic reviews (CRD42022332866) and reports in compliance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The Ovid MEDLINE^®, EMBASE, Web of Science and Cochrane databases were queried in April 2022. The search terms 'irreversible electroporation', 'colon cancer', 'rectum cancer' and 'liver metastases' were used in combinations. Studies were included if they provided information on the use of IRE for patients with colorectal hepatic metastases and reported procedure and disease-specific outcomes. The searches returned 647 unique articles and the exclusions left a total of eight articles. These were assessed for bias using the methodological index for nonrandomized studies (MINORS criteria) and reported using the synthesis without meta-analysis guideline (SWiM).

RESULTS

One hundred eighty patients underwent treatment for liver metastases from colorectal cancer. The median transverse diameter of tumours treated by IRE was <3 cm. Ninety-four (52%) tumours were adjacent to major hepatic inflow/outflow structures or the vena cava. IRE was undertaken under general anaesthesia with cardiac cycle synchronisation and with the use of either CT or ultrasound for lesion localisation. Probe spacing was less than 3.2 cm for all ablations. There were two (1.1%) procedure-related deaths in 180 patients. There was one (0.5%) post-operative haemorrhage requiring laparotomy, one (0.5%) bile leak, five (2.8%) post-procedure biliary strictures and a zero incidence of post-IRE liver failure.

CONCLUSIONS

This systematic review shows that IRE for colorectal liver metastases can be accomplished with low procedure-related morbidity and mortality. Further prospective study is required to assess the role of IRE in the portfolio of treatments for patients with liver metastases from colorectal cancer.

Palliative Treatment of Esophageal Cancer Using Calcium Electroporation

Simple Summary

Calcium electroporation is a new cancer therapy wherein a high, rapid influx of calcium, facilitated by electrical pulses, is used to kill cancer cells. This pilot study aimed to evaluate the safety and feasibility of this new treatment for patients with non-curable esophageal cancer. The treatment was administrated during an endoscopic examination, under general anesthesia, and in an outpatient setting. Eight patients were treated. One severe adverse event occurred (requiring a single blood transfusion) and another three mild side effects were seen. Two patients reported dysphagia relief after treatment and one patient had a partial response evaluated by CT. Six months after treatment, the same patient was still in good condition, without the need for further treatment. Calcium electroporation was conducted in eight patients with only a few side effects. More studies are warranted to evaluate clinical efficacy.

Abstract

Calcium electroporation (CaEP) is a novel cancer therapy wherein high intracellular calcium levels, facilitated by reversible electroporation, trigger tumor necrosis. This study aimed to establish safety with CaEP within esophageal cancer. Patients with non-curable esophageal cancer were included at Copenhagen University Hospital Rigshospitalet in 2021 and 2022. In an outpatient setting, calcium gluconate was injected intratumorally followed by reversible electroporation applied with an endoscopic electrode. The primary endpoint was the prevalence of adverse events, followed by palliation of dysphagia. All patients were evaluated with CT and upper endoscopies up to two months after treatment. The trial was registered at ClinicalTrials.gov (NCT04958044). Eight patients were treated. One serious adverse event (anemia, requiring a single blood transfusion) and three adverse events (mild retrosternal pain (two) and oral thrush (one)) were registered. Initially, six patients suffered from dysphagia: two reported dysphagia relief and four reported no change. From the imaging evaluation, one patient had a partial response, three patients had no response, and four patients had progression. Six months after treatment, the patient who responded well was still in good condition and without the need for further oncological treatment. CaEP was conducted in eight patients with only a few side effects. This study opens the way for larger studies evaluating tumor regression and symptom palliation.

Sudden Occurrence of Pacemaker Capture Failure during Irreversible Electroporation Ablation for Prostate Cancer in Post-COVID-19 Patient: A Case Report

Irreversible electroporation (IRE) ablation is a novel treatment option for localized prostate cancer. Here, we present a case of an abrupt and fatal arrhythmia during the IRE procedure in a prostate cancer patient with an implanted permanent pacemaker. A 78-year-old male patient with a pacemaker due to sick sinus syndrome and syncope was scheduled for IRE prostate ablation surgery under general anesthesia. He had a history of recovering from coronavirus disease 2019 (COVID-19) after having been vaccinated against it and recovered without sequalae. Pacemaker interrogation and reprogramming to asynchronous AOO mode was carried out before surgery, however, sinus pause occurred repeatedly during ablation pulse delivery. After the first sinus pause of 2.25 s there was a decrease in continuous arterial blood pressure (ABP). During the delivery of the second and third pulses, identical sinus pauses were observed due to failure to capture. However, the atrial-paced rhythm recovered instantly, and vital signs became acceptable. Although sinus pause recovered gradually, the duration thereof was increased by the delivery of more IRE pulses, with a subsequent abrupt decrease seen in blood pressure. The pacemaker was urgently reprogrammed to DOO mode, after which there were no further pacing failures and no hemodynamic adverse events. For patients with pacemakers, close cardiac monitoring in addition to the interrogation of the pacemaker during the electromagnetic interference (EMI) procedure is recommended, especially in the case of having a disease that may aggravate cardiac vulnerability, such as COVID-19.

Percutaneous Ablation of Hepatic Tumors at the Hepatocaval Confluence Using Irreversible Electroporation: A Preliminary Study

Background: Tumors at the hepatocaval confluence are difficult to treat, either surgically or ablatively. Methods: A retrospective longitudinal study on patients ineligible for thermal ablation who underwent computed tomography-guided IRE for hepatic tumors at the hepatocaval confluence was conducted. Factors analyzed included patient and tumor characteristics, IRE procedure details, treatment-related complications, and prognosis. Results: Between 2017 and 2021, 21 patients at our institute received percutaneous IRE. Of the 38 lesions, 21 were at the hepatocaval confluence. Complete ablation was achieved in all cases. Local and distant recurrence was observed in 4.8% (1/21) and 42.6% (9/21) of the ablated tumors, respectively. All postcava remained perfused at follow-up, except for 1 (4.8%) hepatic vein near the lesion found to be temporarily occluded and restored within 1 month. The ratio of the maximum diameter of ablation area at 1, 3, and 6 months post procedure compared to that immediately after IRE was 0.68 (0.50–0.84), 0.49 (0.27–0.61), and 0.38 (0.25–0.59), respectively. Progression-free survival of the patients with recurrence was 121 (range, 25–566) days. Four (19.0%) patients died at the end of follow-up with median overall survival of 451.5 (range, 25–716) days. Conclusions: IRE could be a safe and effective treatment for hepatic tumors at the hepatocaval confluence. This article provides valuable prognostic data; further clinical research is needed for better prognosis.

Irreversible Electroporation for Hepatocellular Carcinoma Abutting the Diaphragm: A Prospective Single-center Study

BACKGROUND AND AIMS

Irreversible electroporation (IRE) is an emerging local ablation therapy which may be effective for unresectable tumors. This study aimed to evaluate the safety and efficacy of percutaneous IRE in the treatment of hepatocellular carcinoma (HCC) abutting the diaphragm.

METHODS

A total of 26 participants with 39 tumors abutting the diaphragm were prospectively evaluated between July 2015 and September 2018. Complications associated with IRE were recorded, and the survival benefit of IRE was analyzed. The factors associated with time to local tumor progression (LTP) were analyzed using univariate and multivariate Cox regression models.

RESULTS

No major complications or treatment-related deaths occurred. The technical success rate was 96.2% (25/26) and complete ablation rate was 92.3% (36/39). The median follow-up period was 16.7 months (range: 3.0-43.0 months), the LTP occurred in 15.2% of tumors and median time to LTP was 20.4 months. Overall, tumor size (hazard ratio: 1.24 [95% confidence interval: 0.38, 3.81], p=0.03) was the only factor associated with time to LTP.

CONCLUSIONS

This study shows for the first time that percutaneous IRE is a safe and effective ablation technology for HCC abutting the diaphragm.

Liver-Directed Therapy for Neuroendocrine Metastases: From Interventional Radiology to Nuclear Medicine Procedures

Neuroendocrine neoplasms (NENs) are rare and heterogeneous epithelial tumors most commonly arising from the gastroenteropancreatic (GEP) system. GEP-NENs account for approximately 60% of all NENs, and the small intestine and pancreas represent two most common sites of primary tumor development. Approximately 80% of metastatic patients have secondary liver lesions, and in approximately 50% of patients, the liver is the only metastatic site. The therapeutic strategy depends on the degree of hepatic metastatic invasion, ranging from liver surgery or percutaneous ablation to palliative treatments to reduce both tumor volume and secretion. In patients with grade 1 and 2 NENs, locoregional nonsurgical treatments of liver metastases mainly include percutaneous ablation and endovascular treatments, targeting few or multiple hepatic metastases, respectively. In the present work, we provide a narrative review of the current knowledge on liver-directed therapy for metastasis treatment, including both interventional radiology procedures and nuclear medicine options in NEN patients, taking into account the patient clinical context and both the strengths and limitations of each modality.

Cardiac impact of high-frequency irreversible electroporation using an asymmetrical waveform on liver in vivo

Background

High-Frequency Irreversible Electroporation (H-FIRE) is a novel technology for non-thermal ablation. Different from Irreversible electroporation (IRE), H-FIRE delivers bipolar electrical pulses without muscle contraction and does not cause electrolysis. Currently, little is known regarding the cardiac safety during the administration of H-FIRE on liver. The aim of this study was to evaluate the changes of electrocardiogram (ECG) and biomarkers of cardiac damage during asymmetrical waveform of H-FIRE therapy in vivo.

Methods

The swines (n = 7) in IRE group, which used 100 pulses (2200 V, 100–100 μs configuration), were administrated with muscle relaxant under anesthesia. In the absence of muscle relaxant, 7 swines in H-FIRE group were performed with 2400 pulses (3000 V, 5–3–3–5 μs configuration). Midazolam (0.5 mg/kg) and xylazine hydrochloride (20 mg/kg) were given to induce sedation, followed by Isoflurane (2.5%, 100% oxygen, 3 L/min) to maintain sedation in all the swines. Limb lead ECG recordings were analyzed by two electrophysiologists to judge the arrhythmia. Cardiac and liver tissue was examined by pathology technique.

Results

The ablation zones were larger in H-FIRE than IRE. Both IRE and H-FIRE did not affect the autonomous cardiac rhythm. Even when the electrical signal of IRE and H-FIRE fell on ventricular vulnerable period. Moreover, cTnI in IRE group showed an increase in 4 h after ablation, and decreased to baseline 72 h after ablation. However, cTnI showed no significant change during the administration of H-FIRE.

Conclusions

The study suggests an asymmetrical waveform for H-FIRE is a promising measure for liver ablation. The results were based on normal liver and the swines without potential cardiac diseases. With the limitations of these facts, asymmetrical waveform for H-FIRE of liver tissue seems relatively safe without major cardiac complications. The safety of asymmetrical waveform for H-FIRE needs to evaluate in future.

Pulsed field catheter ablation in atrial fibrillation

Catheter ablation (CA) has become the mainstay therapy for the maintenance of sinus rhythm in patients with atrial fibrillation (AF), with pulmonary vein isolation (PVI) the most frequently used treatment strategy. Although several energy sources have been tested (including radiofrequency, cryothermal and laser), these are not devoid of safety issues and in many instances effectiveness is dependent on operator experience. Pulsed field ablation (PFA) is a novel energy source by which high-voltage electric pulses are used to create pores in the cellular membrane (i.e., electroporation), leading to cellular death. The amount of energy required to produce irreversible electroporation is highly tissue dependent. In consequence, a tailored protocol in which specific targeting of the atrial myocardium is achieved while sparing adjacent tissues is theoretically feasible, increasing the safety of the procedure. While large scale clinical trials are lacking, current clinical evidence has demonstrated significant efficacy in achieving durable PVI without ablation related adverse events.