Effect of irreversible electroporation parameters and the presence of a metal stent on the electric field line pattern

A New Hope for the Treatment of Atrial Fibrillation: Application of Pulsed-Field Ablation Technology

In recent years, the prevalence of and mortality associated with cardiovascular diseases have been rising in most countries and regions. AF is the most common arrhythmic condition, and there are several treatment options for AF. Pulmonary vein isolation is an effective treatment for AF and is the cornerstone of current ablation techniques, which have one major limitation: even when diagnosed and treated at a facility that specializes in ablation, patients have a greater chance of recurrence. Therefore, there is a need to develop better ablation techniques for the treatment of AF. This article first compares the current cryoablation (CBA) and radiofrequency ablation (RFA) techniques for the treatment of AF and discusses the utility and advantages of the development of pulsed-field ablation (PFA) technology. The current research on PFA is summarized from three perspectives, namely, simulation experiments, animal experiments, and clinical studies. The results of different stages of experiments are summarized, especially during animal studies, where pulmonary vein isolation was carried out effectively without causing injury to the phrenic nerve, esophagus, and pulmonary veins, with higher safety and shorter incision times. This paper focuses on a review of various a priori and clinical studies of this new technique for the treatment of AF.

Consensus Guidelines of Irreversible Electroporation for Pancreatic Tumors: Protocol Standardization Using the Modified Delphi Technique

Since no uniform treatment protocol for pancreatic irreversible electroporation (IRE) exists, the heterogeneity throughout literature complicates the comparison of results. To reach agreement among experts, a consensus study was performed. Eleven experts, recruited according to predefined criteria regarding previous IRE publications, participated anonymously in three rounds of questionnaires according to a modified Delphi technique. Consensus was defined as having reached ≥80% agreement. Response rates were 100, 64, and 64% in rounds 1 to 3, respectively; consensus was reached in 93%. Pancreatic IRE should be considered for stage III pancreatic cancer and inoperable recurrent disease after previous local treatment. Absolute contraindications are ventricular arrhythmias, implantable stimulation devices, congestive heart failure NYHA class 4, and severe ascites. The inter-electrode distance should be 10 to 20 mm and the exposure length should be 15 mm. After 10 test pulses, 90 treatment pulses of 1,500 V/cm should be delivered continuously, with a 90-µs pulse length. The first postprocedural contrast-enhanced computed tomography should take place 1 month post-IRE, and then every 3 months. This article provides expert recommendations regarding patient selection, procedure, and follow-up for IRE treatment in pancreatic malignancies through a modified Delphi consensus study. Future studies should define the maximum tumor diameter, response evaluation criteria, and the optimal number of preoperative FOLFIRINOX cycles.

g. Scholten GA, Stommel MWJ, Fütterer JJ, Verdaasdonk RM. The Effect of Partial Electrical Insulation of the Tip and Active Needle Length of Monopolar Irreversible Electroporation Electrodes on the Electric Field Line Pattern and Temperature Gradient to Improve Treatment Control

Unintentional local temperature effects can occur during irreversible electroporation (IRE) treatment, especially near the electrodes, and most frequently near the tip. Partial electrical insulation of the IRE electrodes could possibly control these temperature effects. This study investigated and visualized the effect of partial electrical insulation applied to the IRE electrodes on the electric field line pattern and temperature gradient. Six designs of (partial) electrical insulation of the electrode tip and/or active needle length (ANL) of the original monopolar 19G IRE electrodes were investigated. A semolina in castor oil model was used to visualize the electric field line pattern in a high-voltage static electric field. An optical method to visualize a change in temperature gradient (color Schlieren) was used to image the temperature development in a polyacrylamide gel. Computational models were used to support the experimental findings. Around the electrode tip, the highest electric field line density and temperature gradient were present. The more insulation was applied to the electrodes, the higher the resistance. Tip and ANL insulation together reduced the active area of and around the electrodes, resulting in a visually enlarged area that showed a change in temperature gradient. Electrically insulating the electrode tip together with an adjustment in IRE parameter settings could potentially reduce the uncontrollable influence of the tip and may improve the predictability of the current pathway development.

The Influence of Irreversible Electroporation Parameters on the Size of the Ablation Zone and Thermal Effects: A Systematic Review

Introduction: The aim of this study was to review the effect of irreversible electroporation parameter settings on the size of the ablation zone and the occurrence of thermal effects. This insight would help to optimize treatment protocols and effectively ablate a tumor while controlling the occurrence of thermal effects. Methods: Various individual studies report the influence of variation in electroporation parameters on the ablation zone size or occurrence of thermal effects. However, no connections have yet been established between these studies. With the aim of closing the gap in the understanding of and personalizing irreversible electroporation parameter settings, a systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A quality assessment was performed using an in-house developed grading tool based on components of commonly used grading domains. Data on the electroporation parameters voltage, number of electrodes, inter-electrode distance, active needle length, pulse length/number/protocol/frequency, and pulse interval were extracted. Ablation zone size and temperature data were grouped per parameter. Spearman correlation and linear regression were used to define the correlation with outcome measures. Results: A total of 7661 articles were screened, of which 18 preclinical studies (animal and phantom studies) met the inclusion criteria. These studies were graded as moderate (4/18) and low (14/18) quality. Only the applied voltage appeared to be a significant linear predictor of ablation zone size: length, surface, and volume. The pulse number was moderately but nonlinearly correlated with the ablation zone length. Thermal effects were more likely to occur for higher voltages (≥2000 V), higher number of electrodes, and increased active needle length. Conclusion: Firm conclusions are limited since studies that investigated and precisely reported the influence of electroporation parameters on the ablation zone size and thermal effects were scarce and mostly graded low quality. High-quality studies are needed to improve the predictability of the combined effect of variation in parameter combinations and optimize irreversible electroporation treatment protocols.

Plant-based model for the visual evaluation of electroporated area after irreversible electroporation and its comparison to in-vivo animal data

Electroporation (EP) is widely used in medicine, such as cancer treatment, in form of electrochemotherapy or irreversible electroporation (IRE). For EP device testing, living cells or tissue inside a living organism (including animals) are needed. Plant-based models seem to be a promising alternative to substitute animal models in research. The aim of this study is to find a suitable plant-based model for visual evaluation of IRE, and to compare the geometry of electroporated areas with in-vivo animal data.For this purpose, a variety of fruit and vegetables were selected and visually evaluated after 0/1/2/4/6/8/12/16/24 h post-EP. Apple and potato were found to be suitable models as they enabled a visual evaluation of the electroporated area. For these models, the size of the electroporated area was determined after 0/1/2/4/6/8/12/16/24 h. For apples, a well-defined electroporated area was visual within two hours, while in potatoes it reached a plateau after eight hours only. The electroporated area of apple, which showed the fastest visual results was then compared to a retrospectively evaluated swine liver IRE dataset which had been obtained for similar conditions. The electroporated area of the apple and swine liver both showed a spherical geometry of comparable size. For all experiments, the standard protocol for human liver IRE was followed. To conclude, potato and apple were found to be suitable plant-based models for the visual evaluation of electroporated area after irreversible EP, with apple being the best choice for fast visual results. Given the comparable range, the size of the electroporated area of the apple may be promising as a quantitative predictor in animal tissue. Even if plant-based models cannot completely replace animal experiments, they can be used in the early stages of EP device development and testing, decreasing animal experiments to the necessary minimum.

In Silico Modelling to Assess the Electrical and Thermal Disturbance Provoked by a Metal Intracoronary Stent during Epicardial Pulsed Electric Field Ablation

Background: Pulsed Electric Field (PEF) ablation has been recently proposed to ablate cardiac ganglionic plexi (GP) aimed to treat atrial fibrillation. The effect of metal intracoronary stents in the vicinity of the ablation electrode has not been yet assessed. Methods: A 2D numerical model was developed accounting for the different tissues involved in PEF ablation with an irrigated ablation device. A coronary artery (with and without a metal intracoronary stent) was considered near the ablation source (0.25 and 1 mm separation). The 1000 V/cm threshold was used to estimate the ‘PEF-zone’. Results: The presence of the coronary artery (with or without stent) distorts the E-field distribution, creating hot spots (higher E-field values) in the front and rear of the artery, and cold spots (lower E-field values) on the sides of the artery. The value of the E-field inside the coronary artery is very low (~200 V/cm), and almost zero with a metal stent. Despite this distortion, the PEF-zone contour is almost identical with and without artery/stent, remaining almost completely confined within the fat layer in any case. The mentioned hot spots of E-field translate into a moderate temperature increase (<48 °C) in the area between the artery and electrode. These thermal side effects are similar for pulse intervals of 10 and 100 μs. Conclusions: The presence of a metal intracoronary stent near the ablation device during PEF ablation simply ‘amplifies’ the E-field distortion already caused by the presence of the vessel. This distortion may involve moderate heating (<48 °C) in the tissue between the artery and ablation electrode without associated thermal damage.

Bizonal cardiac engineered tissues with differential maturation features in a mid-throughput multimodal bioreactor

Functional three-dimensional (3D) engineered cardiac tissue (ECT) models are essential for effective drug screening and biological studies. Application of physiological cues mimicking those typical of the native myocardium is known to promote the cardiac maturation and functionality in vitro. Commercially available bioreactors can apply one physical force type at a time and often in a restricted loading range. To overcome these limitations, a millimetric-scale microscope-integrated bioreactor was developed to deliver multiple biophysical stimuli to ECTs. In this study, we showed that the single application of auxotonic loading (passive) generated a bizonal ECT with a unique cardiac maturation pattern. Throughout the statically cultured constructs and in the ECT region exposed to high passive loading, cardiomyocytes predominantly displayed a round morphology and poor contractility ability. The ECT region with a low passive mechanical stimulation instead showed both rat- and human-origin cardiac cell maturation and organization, as well as increased ECT functionality.

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Mid-throughput culture platform to engineer reproducible 3D cardiac in vitro models

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3D culture under multiphysical stimuli mimicking the in vivo heart environment

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Passive loading leads to bizonal constructs with different cardiac maturation stages

Outcomes of irreversible electroporation (IRE) for perihilar cholangiocarcinoma (ALPACA): a prospective pilot study

PURPOSE

To investigate safety and efficacy of percutaneous or open irreversible electroporation (IRE) in a prospective cohort of patients with locally advanced, unresectable perihilar cholangiocarcinoma (PHC).

MATERIALS AND METHODS

In a multicenter phase I/II study patients with unresectable PHC due to extensive vascular involvement or N2 lymph node metastases or local recurrence after resection for PHC were included and treated by open or percutaneous IRE combined with palliative chemotherapy (current standard of care). Primary outcome was the number of major adverse events occurring within 90 days after IRE (grade ≥3) and the upper-limit was predefined at 60%. Secondary outcomes included technical success rate, hospital stay and overall survival (OS).

RESULTS

Twelve patients (mean age 63±12 years) were treated with IRE. The primary outcome of major adverse event rate was 50% (6 out of 12 patients) and no 90-day mortality was observed. All procedures were technically successful, with no intra-procedural adverse events requiring additional interventions. Median OS from diagnosis was 21 months (95% CI 15-27 months), with a one-year survival rate after IRE of 75%.

CONCLUSION

Percutaneous IRE in selected patients with locally advanced PHC seems feasible, with the major adverse event rate of 50% below the predefined upper safety limit in this prospective study. Future comparative research exploring the efficacy of IRE is warranted.

The Effect of Discharge Mode on the Distribution of Myocardial Pulsed Electric Field—A Simulation Study for Pulsed Field Ablation of Atrial Fibrillation

Background: At present, the effects of discharge modes of multielectrode catheters on the distribution of pulsed electric fields have not been completely clarified. Therefore, the control of the distribution of the pulsed electric field by selecting the discharge mode remains one of the key technical problems to be solved. Methods: We constructed a model including myocardium, blood, and a flower catheter. Subsequently, by setting different positive and ground electrodes, we simulated the electric field distribution in the myocardium of four discharge modes (A, B, C, and D) before and after the catheter rotation and analyzed their mechanisms. Results: Modes B, C, and D formed a continuous circumferential ablation lesion without the rotation of the catheter, with depths of 1.6 mm, 2.7 mm, and 0.7 mm, respectively. After the catheter rotation, the four modes could form a continuous circumferential ablation lesion with widths of 10.8 mm, 10.6 mm, 11.8 mm, and 11.5 mm, respectively, and depths of 5.2 mm, 2.7 mm, 4.7 mm, and 4.0 mm, respectively. Conclusions: The discharge mode directly affects the electric field distribution in the myocardium. Our results can help improve PFA procedures and provide enlightenment for the design of the discharge mode with multielectrode catheters.

Lizard-Skin-Inspired Nanofibrous Capillary Network Combined with a Slippery Surface for Efficient Fog Collection

Freshwater shortage is a critical global issue that needs to be resolved urgently. Efficient water collection from fog provides a promising and sustainable solution to produce clean drinking water, especially in the desert and arid regions. Nature has long served as our best source of inspiration for designing new structures and developing new materials. Herein, we report a strategy to design a novel Janus fog collector with a hydrophilic lizard-skin-like nanofibrous network upper surface and hydrophobic slippery lower surface using a simple and feasible method of coating and electrospinning. We analyze the forming law of the lizard-skin-like nanofibrous network structure on different substrates using electric field simulation. The resulting copper mesh-based Janus fog collector exhibits superior water-collecting efficiency (907 mg cm^-2 h^-1) and long-term durability, achieving directional transport of tiny droplets and high-efficiency water collection. However, there are few reports on the combination of the lizard-skin-like nanofibrous capillary network and slippery surface for efficient fog collection. Therefore, we believe that this work will open a new avenue to collect water efficiently and also provide clues to research on the lizard-skin-like nanofibrous network structure.