Multi-electrode System Research Articles

Distribution of volumes of plasma channels components between metal granules in working liquids

Introduction. Expanding the capabilities of a number of modern technologies and improving quality of their products require detailed spark and plasma erosion processes control in metal granules layers (MGL). Problem. Traditional measurement of exclusively electrical parameters of these processes, even in the case of multi-electrode systems, provides only a general vision, not allowing monitoring processes in individual plasma channels. Optical control methods make it possible to simultaneously have information about almost every plasma channel in the MGL. The aim of the article is to study the characteristic components of plasma channels arising as a result of the flow of discharge currents in the MGL and to establish the laws of distribution of their volumes and their ratios. Methodology. During the experiments, photographs of plasma channels resulting from the flow of discharge current pulses between Al granules immersed in distilled water were obtained. Using the specialized ToupView program, the volumes of equivalent ellipsoids of rotation, approximating the colored halos and white cores of the plasma channels were determined. Discrete distributions of the volumes of the halo and cores of plasma channels, as well as their ratios were constructed both with and without procedures for screening out «anomalous» results. The efficiency of approximation of discrete distributions obtained in practice by continuous theoretical distributions Weibull, Rosin-Rammler and log-normal was estimated. Results. It is shown that of all the considered theoretical distributions of halo and cores of plasma channels volumes, as well as their ratios, the most adequate is the log-normal one. Originality. For the first time distributions of volumes of halo and cores of plasma channels were studied and their comparative analysis with the size distributions of erosion particles and dimples on the surface of Al granules was given. Practical significance. Taking into account the new obtained results, a technique for constructing distributions of volumes of halo and cores of plasma channels and determining their parameters has been developed. References 53, figures 7, tables 5.

Optimizing power generation in sediment microbial fuel cells through multi-electrode configurations

BackgroundSediment microbial fuel cells (SMFCs) are efficient platforms for electricity generation and organic/inorganic material removal from sediment. The use of multi-electrode systems is vital for enhancing power and current generation while ensuring stability under bioturbation processes. MethodsThis study investigates the influence of anode and cathode configurations on the performance of various SMFCs with constant total electrode area and identical sediment. We specifically analyzed the impact of one, two, four, and eight graphite electrodes as anodes and cathodes in four SMFC setups. Cyclic voltammetry (CV) and impedance tests were conducted to assess performance. Significant findingsResults show that the four-anode configuration exhibited increased current generation, while having four cathodes improved performance according to impedance tests. However, using eight cathodes led to decreased power and increased ohmic resistance due to cathodic restriction. SMFC A, with eight anodes and four cathodes, achieved a peak power output of 394 μW, while SMFC B, with four anodes and cathodes, reached a maximum current of 1600 μA. These values represent significant enhancements compared to single-anode setups with the same electrode surface area. This study highlights the potential for improving SMFC performance through strategic multi-electrode configurations.

Therapeutic Efficacy of Mexiletine for Long QT Syndrome Type 2: Evidence From Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes, Transgenic Rabbits, and Patients.

Despite major advances in the clinical management of long QT syndrome, some patients are not fully protected by beta-blocker therapy. Mexiletine is a well-known sodium channel blocker, with proven efficacy in patients with sodium channel-mediated long QT syndrome type 3. Our aim was to evaluate the efficacy of mexiletine in long QT syndrome type 2 (LQT2) using cardiomyocytes derived from patient-specific human induced pluripotent stem cells, a transgenic LQT2 rabbit model, and patients with LQT2. Heart rate-corrected field potential duration, a surrogate for QTc, was measured in human induced pluripotent stem cells from 2 patients with LQT2 (KCNH2-p.A561V, KCNH2-p.R366X) before and after mexiletine using a multiwell multi-electrode array system. Action potential duration at 90% repolarization (APD90) was evaluated in cardiomyocytes isolated from transgenic LQT2 rabbits (KCNH2-p.G628S) at baseline and after mexiletine application. Mexiletine was given to 96 patients with LQT2. Patients were defined as responders in the presence of a QTc shortening ≥40 ms. Antiarrhythmic efficacy of mexiletine was evaluated by a Poisson regression model. After acute treatment with mexiletine, human induced pluripotent stem cells from both patients with LQT2 showed a significant shortening of heart rate-corrected field potential duration compared with dimethyl sulfoxide control. In cardiomyocytes isolated from LQT2 rabbits, acute mexiletine significantly shortened APD90 by 113 ms, indicating a strong mexiletine-mediated shortening across different LQT2 model systems. Mexiletine was given to 96 patients with LQT2 either chronically (n=60) or after the acute oral drug test (n=36): 65% of the patients taking mexiletine only chronically and 75% of the patients who performed the acute oral test were responders. There was a significant correlation between basal QTc and ∆QTc during the test (r= -0.8; P<0.001). The oral drug test correctly predicted long-term effect in 93% of the patients. Mexiletine reduced the mean yearly event rate from 0.10 (95% CI, 0.07-0.14) to 0.04 (95% CI, 0.02-0.08), with an incidence rate ratio of 0.40 (95% CI, 0.16-0.84), reflecting a 60% reduction in the event rate (P=0.01). Mexiletine significantly shortens cardiac repolarization in LQT2 human induced pluripotent stem cells, in the LQT2 rabbit model, and in the majority of patients with LQT2. Furthermore, mexiletine showed antiarrhythmic efficacy. Mexiletine should therefore be considered a valid therapeutic option to be added to conventional therapies in higher-risk patients with LQT2.

The effect of multielectrode galvanic corrosion behavior and area ratio on 6061 aluminum alloy, Q235 stainless steel, and carbon fiber composites

AbstractIn this work, electrochemical experiments and numerical simulation methods are employed to study the multielectrode galvanic corrosion behavior of 6061‐Q235‐CFRP, and discuss the influence of the cathode and anode area ratio on the multielectrode galvanic corrosion behavior. The results show that in the 6061‐Q235‐CFRP multielectrode corrosion system, 6061 aluminum alloy is the only anode, and Q235 as well as CFRP are both cathodes. In a multielectrode galvanic system of 6061‐Q235‐CFRP, the current density of 6061 is slightly smaller than the sum of the current densities of 6061 in two galvanic systems of 6061‐Q235 as well as 6061‐CFRP. Moreover, the potential of the galvanic system shifts negatively and the current density decreases gradually with the increasing area of 6061, which has a logarithmic relationship with the area of the cathode and anode. While the current density increases with the increasing area of Q235 or CFRP.

Advances in radiofrequency ablation: mechanism of action and technology.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality that utilizes high-frequency alternating current to destroy targeted tissues through thermal ablation. This manuscript provides an overview of the advancements in RFA, focusing on its mechanism of action and technological innovations. RFA technology was first introduced in the early 1900's, and its use has expanded and evolved, especially in its current utility in the treatment of painful conditions. As the technology has evolved, new techniques, applications and modalities have expanded its use and improved its efficacy. RFA works by applying radiofrequency energy through specialized electrodes, leading to resistive heating and coagulation necrosis. Its advantages include precise tissue targeting, minimal invasiveness, reduced complications, and faster recovery compared to traditional surgical interventions. Technological advancements in RFA have led to improved treatment outcomes. Multi-electrode systems allow for larger ablation zones. Image-guided RFA improves treatment planning and minimizes damage to healthy tissues. Cooled-tip and perfusion electrodes address limitations such as heat sink effects, enhancing RFA's efficacy in challenging anatomical regions. These developments have expanded RFA's applications to liver tumors, lung tumors, renal tumors, cardiac arrhythmias, and chronic pain syndromes. In conclusion, RFA has emerged as a safe and effective thermal ablation technique. Understanding its mechanism of action and integrating advanced technologies have significantly enhanced treatment outcomes. Continued research and innovation in RFA hold immense potential for further improving patient care and outcomes.

Multimodal breast cancer risk classifier based on biomaterial impedance analysis

Purpose of the research. Breast cancer is the most common malignant tumor among women in Europe and its early detection plays a leading role in reducing mortality rates. Currently, X-ray mammography is the standard screening method for detecting breast cancer. However, due to the morphological similarities between benign and malignant lesions, many of the positive screening mammograms are false positive (up to 40%). Therefore, automation and intellectualization of this process is an urgent task.Methods. The presented studies examine the problems of finding new, highly sensitive, prompt and non-invasive methods for detecting malignant tumors, based on the use of modern computer and telecommunication technologies, which make it possible not only to identify early manifestations of a pathological focus, but also to monitor the process of the effectiveness of therapy without significant harm to the patient’s health.Results. The presented model of a multi-channel classifier integrates the capabilities of multi-frequency bioimpedance measurements and matrix acquisition of information from the surface of human skin through multi-electrode matrix systems. To do this, based on a matrix of electrodes, 3D mapping of the skin surface in problem areas is carried out. Through multi-frequency scanning, we obtain a three-dimensional bioimpedance image, which is analyzed by a convolutional neural network and/or by a decision maker. The proposed solution allows simultaneous analysis of data by an expert (bioimpedance image) and a convolutional neural network (trained classifier), which leads to a reduction in false positive results.Conclusion. The possibilities of multichannel monitoring open up prospects for constructing impedance multidimensional "portraits" of malignant tumors. To classify “portraits” (diagnostics and preclinical diagnostics), methods and algorithms for image recognition and classification are used.

Long-Term Changes in Atrial Arrhythmia Burden After Renal Denervation Combined With Pulmonary Vein Isolation: SYMPLICITY-AF

BackgroundThe autonomic nervous system plays an important role in atrial fibrillation (AF) and hypertension. Renal denervation (RDN) lowers blood pressure (BP), but its role in AF is poorly understood. ObjectivesThe purpose of this study was to investigate whether RDN reduces AF recurrence after pulmonary vein isolation (PVI). MethodsThis study randomized patients from 8 centers (United States, Germany) with drug-refractory AF for treatment with PVI+RDN vs PVI alone. A multielectrode radiofrequency Spyral catheter system was used for RDN. Insertable cardiac monitors were used for continuous rhythm monitoring. The primary efficacy endpoint was ≥2 minutes of AF recurrence or repeat ablation during all follow-up. The secondary endpoints included atrial arrhythmia (AA) burden, discontinuation of class I/III antiarrhythmic drugs, and BP changes from baseline. ResultsA total of 70 patients with AF (52 paroxysmal, 18 persistent) and uncontrolled hypertension were randomized (RDN+PVI, n = 34; PVI, n = 36). At 3.5 years, 26.2% and 21.4% of patients in RDN+PVI and PVI groups, respectively, were free from the primary efficacy endpoint (log rank P = 0.73). Patients with mean ≥1 h/d AA had less daily AA burden after RDN+PVI vs PVI (4.1 hours vs 9.2 hours; P = 0.016). More patients discontinued class I/III antiarrhythmic drugs after RDN+PVI vs PVI (45% vs 14%; P = 0.040). At 1 year, systolic BP changed by −17.8 ± 12.8 mm Hg and −13.7 ± 18.8 mm Hg after RDN+PVI and PVI, respectively (P = 0.43). The composite safety endpoint was not significantly different between groups. ConclusionsIn patients with AF and uncontrolled BP, RDN+PVI did not prevent AF recurrence more than PVI alone. However, RDN+PVI may reduce AF burden and antiarrhythmic drug usage, but this needs further prospective validation.

Simultaneous Determination of Chemical Oxygen Demand, Total Nitrogen, Ammonia, and Phosphate in Surface Water Based on a Multielectrode System.

A technique for monitoring chemical oxygen demand (COD), total nitrogen (TN), ammonia (N-NH4), and phosphate (P-PO4) in surface water with a targeted signal multielectrode system (Cu, Ir, Rh, Co(OH)2, and Zr(OH)4 electrodes) is proposed for the first time. Each water quality index is specifically detected by at least two electrodes with distinct selectivity sensing mechanisms. Cyclic voltammetry and electrochemical impedance measurements are employed for multidimensional signal acquisition, complemented by normalization and Least Absolute Shrinkage and Selection Operator (LASSO) for principal feature extraction and dimension reduction. Multiple linear regression (MLR), partial least-squares (PLS), and eXtreme Gradient Boosting (XGBoost) were employed to evaluate the established prediction model. The precisions of the multielectrode system are ±10%/±5 ppm of COD, ±10%/±0.2 ppm of TN, ±5%/±0.1 ppm of N-NH4, and ±5%/±0.01 ppm of P-PO4. The analysis time of the multielectrode system is reduced from hours to minutes compared with traditional analysis, without any sample pretreatment, facilitating continuous online monitoring in the field. The developed multielectrode system offers a feasible strategy for online in situ monitoring of surface water quality.

Stacking and design optimization of novel plant microbial fuel cell based on dwarf indoor decorative and culinary plants as a compact biobattery for a low energy consumption devices

This article presents the development of a novel compact plant microbial fuel cell (PMFC) constructed with discarded food packagings as a stand-alone power supply for low-power devices suitable for indoor use in real time. A two-modular PMFC with 0.6 L-capacity units with multi-electrode system, connected in parallel inside and joined in series outside, provided power for a 1.5 V, 4.3–105.2 mkA digital thermometer/hygrometer, and a three-modular PMFC ensured operation of a 3 V, 10.1–36.4 mkA weather station or LEDs during the year of the experiment. PMFC with a shortened (1 cm) electrode distance and increased cathode surface area (cathode:anode ratio 1.5:1) using H. soleirolii were characterized by higher bioelectricity output. The maximal current and power density were 407 mA/m2 and 188.33 mW/m2, respectively. Stacking of PMFC modules by combining parallel-series connection with reduction of the interelectrode distance and adjusting the electrodes area is a promising way to improve bioelectricity output for development of compact biobatteries.

Разработка и исследование имитационной модели мультикамерного разрядника для грозозащитного троса

Optical fiber overhead ground wire (OPGW) is an effective solution for laying mainline digital communications along high-voltage power lines. It allows you to use the existing infrastructure of the power grid and ensure the transfer of a large amount of data. The flow of lightning currents and short-circuit currents can cause a violation of the thermal resistance of the fiber and a deterioration of its performance. When the OPGW is insulated through an insulator shunted by a spark gap, during operation it is possible to change the distance in the discharge gap due to the displacement of the electrodes in the plane. Also, when the short circuit location is close, multiple overlaps will occur and as a result, short circuit current will flow through the OPGW. Thus, the article considers the possibility to use a device with a multielectrode system developed on the principle of a multichamber spark gap as a replacement of the spark gap to increase the reliability of the unit with an isolated OPGW suspension. Modeling of the device has been carried out in the ANSYS Maxwell software package, the mathematical apparatus of which is based on the use of Maxwell's differential equations and the finite element method, which allows performing numerical modeling with sufficiently high accuracy. A simulation model of a multichamber spark gap has been developed in the ANSYS Maxwell software package and calculations of electrical characteristics have been performed. For the electrode system of a multi-chamber arrester, an uneven distribution of the applied voltage across the spark discharge gaps of the chambers is determined. It is shown that when a voltage is applied to a spark gap, the highest electric field strength occurs between the first and second electrodes, and then a cascade of discharge gaps occurs, which provides the required low discharge voltages of the spark gap as a whole. The developed simplified simulation model of a multi-chamber arrester has shown all the necessary conditions for cascade imaging of the voltage distribution and the electric-field strength of various electrode options. Based on the research conducted electrodes geometry is identified for smart prototype development and ongoing multi-chamber arrester research.

Evaluation of Hand Action Classification Performance Using Machine Learning Based on Signals from Two sEMG Electrodes.

Classification-based myoelectric control has attracted significant interest in recent years, leading to prosthetic hands with advanced functionality, such as multi-grip hands. Thus far, high classification accuracies have been achieved by increasing the number of surface electromyography (sEMG) electrodes or adding other sensing mechanisms. While many prescribed myoelectric hands still adopt two-electrode sEMG systems, detailed studies on signal processing and classification performance are still lacking. In this study, nine able-bodied participants were recruited to perform six typical hand actions, from which sEMG signals from two electrodes were acquired using a Delsys Trigno Research+ acquisition system. Signal processing and machine learning algorithms, specifically, linear discriminant analysis (LDA), k-nearest neighbors (KNN), and support vector machines (SVM), were used to study classification accuracies. Overall classification accuracy of 93 ± 2%, action-specific accuracy of 97 ± 2%, and F1-score of 87 ± 7% were achieved, which are comparable with those reported from multi-electrode systems. The highest accuracies were achieved using SVM algorithm compared to LDA and KNN algorithms. A logarithmic relationship between classification accuracy and number of features was revealed, which plateaued at five features. These comprehensive findings may potentially contribute to signal processing and machine learning strategies for commonly prescribed myoelectric hand systems with two sEMG electrodes to further improve functionality.

Improved seizure liability detection by combining rat hippocampal brain slice electrophysiology with in vivo behavior observation following intracerebroventricular drug administration

An adverse effect of drug candidates, seizure is a serious issue in drug development. Improving evaluation systems for seizure liability is crucial for selecting good candidates. Firstly, in vitro electrophysiological measurement by a multielectrode array system in rat hippocampal brain slices was employed to confirm an increase in electrically evoked population spike (PS) area, the occurrence of multiple population spikes (MPSs), and thereby the seizure liability of five positive control chemicals: picrotoxin, 4-aminopyridine, pentylenetetrazole, penicillin G, and chlorpromazine. Aspirin, a negative control, did not affect PS area or generate MPSs. Furthermore, baclofen, an anticonvulsant drug, decreased PS area and inhibited the increase in PS area or occurrence of MPSs induced by picrotoxin. A comparative study of seizure liability among carbapenem antibiotics revealed that tienam > carbenin > omegacin and finibax. Despite leading to a strong decrease in PS area, physostigmine, cisplatin, and paroxetine still produced MPSs. Therefore, the increase in PS area or the occurrence of the MPS are considered significant evaluation parameters for seizure liability.In contrast, the in vitro electrophysiological measurement could not detect the seizure liability of diphenhydramine or fluvoxamine. A follow-up study of in vivo mouse behavioral change induced by intracerebroventricular administration of these drugs clearly detected convulsions. The in vitro electrophysiological study using hippocampal brain slices combined with in vivo behavior observation study of drug candidates administered by intracerebroventricular injection can implement to assess the seizure liability of even small amounts, especially in the early stages of drug development.

Optimizing IRE targeting using multi-electrode structure and biomedical multi-output generator

PurposeThis paper aims to study the feasibility of proposed method to focus the electroporation ablation by mean of multi-output multi-electrode system.Design/methodology/approachThe proposed method has been developed based on a previously designed electroporation system, which has the capabilities to modify the electric field distribution in real time, and to estimate the impedance distribution. Taking into consideration the features of the system and biological tissues, the problem has been addressed in three phases: modeling, control system design and simulation testing. In the first phase, a finite element analysis model has been proposed to reproduce the electric field distribution within the hepatic tissue, based on the characteristics of the electroporation system. Then, a control strategy has been proposed with the goal of ensuring complete ablation while minimizing the affected volume of healthy tissue. Finally, to check the feasibility of the proposal, several representative cases have been simulated, and the results have been compared with those obtained by a traditional system.FindingsThe proposed method achieves the proposed goal, as part of a complex electroporation system designed to improve the targeting, effectiveness and control of electroporation treatments and serve to demonstrate the feasibility of developing new electroporation systems capable of adapting to changes in the preplanning of the treatment in real-time.Originality/valueThe work presents a thorough study of control method to multi-output multi-electrode electroporation system by mean of a rigorous numerical simulation.

A multi-electrode system for Pulsed Electric Field treatment chamber

In Pulsed Electric Field treatment systems, fruit juice is treated with high voltage electric pulses to inactivate microorganisms and prolong shelf life. In such a system, a uniform distribution of electric field is required throughout the chamber to ensure consistency in microbial inactivation. In big static treatment chambers, the production of a uniform electric field using large electrodes is impractical due to the difficulty of fabrication and installation. In this work, a method to replace these large electrodes with multiple numbers of small cylindrical electrodes is introduced. Field distributions of six different multi-electrode patterns were compared using COMSOL Multiphysics software, and a 7-electrode pattern was observed to produce the most uniform field distribution. This result was experimentally validated by measuring the impedance of apple pulp after electric field treatment inside fabricated chambers. Thus, 7-electrode design was found to be the most optimal arrangement to produce a uniform field distribution inside big static chambers used for Pulsed Electric Field treatment of fruit juice.

Electrochemical treatment of wastewaters containing metal-organic complexes: A one-step approach for efficient metal complex decomposition and selective metal recovery

Metal-organic complexes, especially those of ethylenediaminetetraacetic acid (EDTA) with metals such as copper (Cu) and nickel (Ni) (denoted here as Cu-EDTA and Ni-EDTA), are common contaminants in wastewaters from chemical and plating industries. In this study, a multi-electrode (ME) system using a two-chamber reactor and two pairs of electrodes is proposed for simultaneous electrochemical oxidation of a wastewater containing both Cu-EDTA and Ni-EDTA complexes as well as separation and selective recovery of Cu and Ni onto two different cathodes via electrodeposition. Our results demonstrate that the ME system successfully achieved 90% EDTA removal, 99% solid Cu recovery at the Cu recovery cathode and 56% Ni recovery (33.3% on the Ni recovery cathode and 22.6% in the solution) after a four-hour operation. The system further achieved 85.5% Ni recovery after consecutive five cycles of operation for 20 h. While Cu removal was mainly driven by the direct reduction of EDTA-complexed Cu(II) at the cathode, oxidation of EDTA within the Ni-EDTA complex at the anode was a prerequisite for Ni removal. The oxidation of metal-bound EDTA and free EDTA was driven by •OH and direct electron transfer on the PbO2 anode surface and graphite anode, respectively. We further show that ME system performs well for all pH conditions, treatment of real wastewaters as well as wastewaters containing other metals ions (Cr and Zn) along with Cu/Ni. The separation efficiency of Cu and Ni is dependent on applied electrode potential as well as nature and concentration of binding ligand present with comparatively lower separation efficiency achieved in the presence of weaker binding capacity and/or at lower ligand concentration and lower applied electrode potential. As such, some optimization of electrode potential is required depending on the nature/concentration of ligands in the wastewaters. Overall, this study provides new insights into the design and operation of EAOP technology for effective organic abatement and metal recovery from wastewaters containing mixtures of various metal-organic complexes.

An algorithm for electrocardiosignals processing in a multielectrode electrocardiological screening system for visualization of the electrical potential of the epicardium

An algorithm for electrocardiosignals processing in a multielectrode electrocardiological screening system for visualization of the electrical potential of the epicardium

Adaptive frequency-domain filtering for neural signal preprocessing

Electrical interference from various sources is a common issue for experimental extracellular electrophysiology recordings collected using multi-electrode array neural recording systems. This interference deteriorates the signal-to-noise ratio (SNR) of the raw electrophysiology signals and hampers the accuracy of data post-processing using techniques such as spike-sorting. Traditional signal processing methods to digitally remove electrical interference during post-processing include bandpass filtering to limit the signal to the relevant spectral range of the biological data, e.g., the spikes band (300 Hz - 7 kHz), targeted notch filtering to remove power line interference from standard alternating current mains electricity and common reference removal to minimize noise common to all electrodes. These methods require a priori knowledge of the frequency of the interfering signal source to address the unique electromagnetic interference environment of each experimental setup. We discuss an adaptive method for automatically removing narrow-band electrical interference through a spectral peak detection and removal (SPDR) step that can be applied during post-processing of the recorded data, based on the intuition that tall, narrowband signals localized in the signal spectrum correspond to interference, rather than the activity of neurons. A spectral peak prominence (SPP) threshold is used to detect these peaks in the frequency domain, which will then be removed via notch filtering. We applied this method to simulated waveforms and also experimental electrophysiology data collected from cerebral organoids to demonstrate its effectiveness for removing unwanted interference without significantly distorting the neural signals. We discuss that proper selection of the SPP threshold is required to avoid over-filtering, which can result in distortion of the electrophysiology data. We also compare the firing-rate activity in the filtered electrophysiology with fluorescence calcium imaging, a secondary cellular activity marker, to quantify signal distortion and provide bounds on SNR-based optimization of the SPP threshold. The adaptive filtering technique demonstrated in this paper is a powerful method that can automatically detect and remove interband interference in recorded neural signals, potentially enabling data collection in more naturalistic settings where external interference signals are difficult to eliminate.

Safety and Efficacy of Renal Denervation in Patients Taking Antihypertensive Medications

BackgroundRenal denervation (RDN) reduces blood pressure (BP) in patients with uncontrolled hypertension in the absence of antihypertensive medications. ObjectivesThis trial assessed the safety and efficacy of RDN in the presence of antihypertensive medications. MethodsSPYRAL HTN-ON MED is a prospective, randomized, sham-controlled, patient- and assessor-blinded trial enrolling patients from 56 clinical centers worldwide. Patients were prescribed 1 to 3 antihypertensive medications. Patients were randomized to radiofrequency RDN or sham control procedure. The primary efficacy endpoint was the baseline-adjusted change in mean 24-hour ambulatory systolic BP at 6 months between groups using a Bayesian trial design and analysis. ResultsThe treatment difference in the mean 24-hour ambulatory systolic BP from baseline to 6 months between the RDN group (n = 206; −6.5 ± 10.7 mm Hg) and sham control group (n = 131; −4.5 ± 10.3 mm Hg) was −1.9 mm Hg (95% CI: −4.4 to 0.5 mm Hg; P = 0.12). There was no significant difference between groups in the primary efficacy analysis with a posterior probability of superiority of 0.51 (Bayesian treatment difference: −0.03 mm Hg [95% CI: −2.82 to 2.77 mm Hg]). However, there were changes and increases in medication intensity among sham control patients. RDN was associated with a reduction in office systolic BP compared with sham control at 6 months (adjusted treatment difference: −4.9 mm Hg; P = 0.0015). Night-time BP reductions and win ratio analysis also favored RDN. There was 1 adverse safety event among 253 assessed patients. ConclusionsThere was no significant difference between groups in the primary analysis. However, multiple secondary endpoint analyses favored RDN over sham control. (SPYRAL HTN-ON MED Study [Global Clinical Study of Renal Denervation With the Symplicity Spyral Multi-electrode Renal Denervation System in Patients With Uncontrolled Hypertension in the Absence of Antihypertensive Medications]; NCT02439775)

Zero-fluoroscopy ablation with multielectrode pulse field ablation system: Case series.

Pulse field ablation (PFA) is a novel nonthermal ablation modality for treatment of atrial fibrillation. While mostly lacking 3D electroanatomical mapping integration, reported radiation doses in procedures using multielectrode PFA catheters are relatively high. We report a first case series of three patients where a zero-fluoroscopy approach by intracardiac echocardiography was utilized and present a possible workflow for zero-fluoroscopy ablation with the Farapulse PFA system.

A novel polarity configuration for enhancing ablation depth of pulsed field ablation: Design, modeling, and in vivo validation.

Pulsed field ablation (PFA) has been increasingly used to cut off the delivery of abnormal electrical signals in the treatment of cardiac arrhythmias. A successful cut off requires forming a layer of transmural damage on the heart wall, and this layer depends on the depth of ablation by PFA. This study aims to propose a novel polarity configuration of PFA to increase the ablation depth in the treatment of cardiac arrhythmias. A novel polarity configuration was designed for a multi-electrode system, where the number of electrodes is greater than two. The polarity configuration in such multi-electrode system is called the paired-electrode interlaced configuration (PIC). The existing configuration called the single-electrode interlaced configuration (SIC) was used to compare with the PIC. To both the SIC and PIC, a full-SIC or a full-PIC is called when all electrodes (anode, cathode) in a catheter is used otherwise partial-SIC or partial-PIC is called. By the comparison between the full-SIC and full-PIC, the benefit of the PIC was exhibited as opposed to the SIC, but an extra ablation step was added in the PIC in order to form a continuous ablation zone. The other comparative study was taken between a partial-PIC and a partial-SIC with the same number of ablation step. In this study, a rabbit model was built by infusing 0.4% saline solution (at 37°C) into the rabbit's abdominal cavity which surrounds the liver. This model was considered as a biometric environment of the heart, namely cardiac-mimetic model (CMM). The experimental results have shown that the full-PIC is superior to the full-SIC in the ablation depth, specifically in both the maximum (4.14±0.55mm vs. 3.35±0.26mm, p<0.01) and the minimum (3.18±0.29mm vs. 2.76±0.28mm, p<0.05), and in the ablation width, specifically only in the maximum (8.27±0.76mm vs. 7.09 ± 0.51mm, p=0.019) under an identical ablation time (i.e., 5s). It is noted that the minimum ablation width did not show a significant difference between the full-PIC and full-SIC (specifically, 5.61±0.86mm vs. 4.67±0.73mm, p=0.069). Considering the lethal electric field threshold (LEFT) to be 600V/cm for liver tissues, the maximum and minimum ablation depth generated by the full-PIC was found larger than that by the full-SIC (3.90vs. 3.52mm, and 3.03vs. 2.48mm, respectively) in the simulation. Meanwhile, similar experiment results by comparing the partial-PIC and partial-SIC have been obtained, which shows a significant increase in both the maximum ablation depth (4.81±0.87mm vs. 3.30±0.73mm, p<0.001) and the maximum ablation width (8.19±0.85mm vs. 6.47±1.13mm, p=0.001). (1) The electric field in the PIC is concentrated around the pair of electrodes, and the pattern of the field is a significant factor in the energy delivery along the direction of the depth. (2) The increase of the ablation depth can significantly expand the range of the tissue on the heart, where the PFA can apply, and can therefore readily form a layer of transmural damage on the heart wall at positions at which the wall is thicker.