Electric Ablation Research Articles

Pulsed Field Ablation in the Treatment of Cardiac Arrhythmias: A State-of-the-art Review

Abstract Pulsed-field ablation (PFA), specifically irreversible electroporation, induces cell membrane damage through the formation of irreversible pores, leading to apoptosis and necrosis, with applications in tumor treatment and myocardium ablation since 2007. This review is on PFA in the treatment of cardiac arrhythmias, including the basic principles, clinical applications, and hot issues of PFA. Presently, the pulsed electric field has demonstrated its effectiveness and safety in the treatment of atrial fibrillation, which is not inferior to that of traditional thermal energy. Research and application on pulsed electric ablation is rapidly advancing due to its advantages of rapidity and specificity in lesion creation. Moreover, pulsed electric ablation has reduced the difficulty of catheter manipulation in pulmonary vein isolation, making it an available treatment to benefit more patients.

Microstructure and Properties of ZrB2-SiC Reinforced Copper Matrix Composite Coatings Prepared by Laser Cladding.

With the use of electrolytic Cu powder, Zr powder, Si powder and nickel-coated B4C powder as cladding powders, in-situ synthesized ZrB2-SiC reinforced copper matrix composite coatings were prepared by laser cladding on the surface of the copper substrate to improve the surface hardness and wear resistance. Under the condition of a laser energy density at 60 kJ/cm2, the macroscopic surface of the composite coating was continuously flat. The microstructure and phase of the cladding coating were analyzed by means of XRD and SEM. The reinforcements with nano-scale particle and micron-scale needle-like structures were in-situ synthesized in the cladding coating, and the content of the reinforcement phase decreased slightly from the coating surface to the substrate. The phase analysis results showed that the reinforcements included ZrB2 and SiC. When the content of the reinforcement was increased to 30 wt%, microhardness also increased from 48 HV0.2 to 309 HV0.2, which was about 5.6 times that of the copper matrix. The wear resistance of the composite coatings was characterized by current-carrying wear tests. By keeping the sliding speed and load constant, the wear rate decreased with an increase in the reinforcement content, and the wear mechanism changed from adhesive wear to abrasive wear. The wear rate of the composite coating with the current was higher than that without the current due to its electric ablation and high temperature.

Experimental Study on the Properties of Copper Base Alloy by Laser Cladding on the Surface of Pure Copper Contact

Arc ablation is the main reason for the failure of pure copper switches. In order to improve the electric ablation resistance of pure copper contacts, Cu-W-Ni alloy cladding layers with different tungsten contents were prepared on the surface of pure copper matrix by laser cladding technology. The microstructure, composition distribution, hardness and corrosion resistance of the cladding layer were analyzed. The results show that the surface of the cladding layer and the pure copper matrix is metallurgical, without holes, cracks and other defects, and the dilution rate is low, and the average hardness is significantly increased. On the whole, the comprehensive properties of CuW10Ni3 cladding layer are slightly better than the other two Cu-W-Ni cladding layers. Compared with the pure copper matrix, the contact hardness is significantly improved under the premise of ensuring the electric conductivity of the inner pure copper matrix.

Fabrication and characterization of W/Cu/Ni-based high specific gravity alloy with Zr and Ti combined addition

W/Cu/Ni-based high specific gravity alloys with Zr and Ti combined addition were successfully prepared through mechanical ball milling combined with spark plasma sintering. The morphologies, structural evolutions, and compositions of the W/Cu/Ni-based composites were thoroughly studied through scanning electron microscopy, energy dispersive spectrometry, and high-resolution transmission electron microscopy. Results reveal that the prepared (Zr, Ti)-doped W/Cu/Ni-based composite has completely compact structure and uniform element distribution after sintering, resulting in the W/Cu/Ni-based alloys with superior microhardness (up to 911.9). The Ti and Ni elements combined to form TixNiy intermetallic compounds, and the CuxZry intermetallic compounds were formed by the combination of Cu and Zr elements. The electrical properties of the W/Cu/Ni-based composites were also explored in detail. The electrical conductivity of the W/Cu/Ni composite increased from 13.2 MS/m to 19.9 MS/m, and the mass loss of electric ablation decreased from 6.20 mg to 1.21 mg through Zr and Ti combined addition. Hence, the W/Cu/Ni-based alloys with Zr and Ti combined addition provide an effective support for future electrical contact materials in electrical and electronic fields.

Effect of Nickel–Phosphorus and Nickel–Molybdenum Coatings on Electrical Ablation of Small Electromagnetic Rails

The electromagnetic rail catapult is a device that converts electrical energy into kinetic energy, which means that the strength of electrical energy directly affects the muzzle speed of armature. In addition, the electrical conductivity, electromagnetic rails and armature surface roughness, and the holding force of the rail are influencing factors that cannot be ignored. However, the electric ablation on the surface of the electromagnetic rails caused by high temperatures seriously affects the service life performance of the electromagnetic catapult system. In this study, electrochemically deposited nickel-phosphorus and nickel-molybdenum alloy coatings are plated on the surface of electromagnetic iron rails and their effects on the reduction of ablation are investigated. SEM (scanning electron microscopy) with EDS (energy dispersive spectroscopy) detector, XRD (X-ray diffraction), 3D optical profiler, and Vickers microhardness tester are used. Our results show that the sliding velocity of the armature decreases slightly with the increased roughness of the rail coating surface. On the other hand, the area of electric ablation on the rail surface is inversely related to the hardness of the rail material. The electrically ablated surface areas of the rails are in: annealed nickel–molybdenum < nickel–molybdenum < annealed nickel–phosphorus < nickel–phosphorus < iron material. Heat treatment at 400 and 500 °C, respectively for Ni–P and Ni–Mo alloys, significantly increases hardness due to the precipitation of intermetallic compounds such as Ni3P and Ni4Mo phases. Comprehensive data analysis shows that the annealed nickel–molybdenum coating has the best electrical ablation wear resistance. The possible reason for that might be attributed to the high hardness of the heat-treated nickel–molybdenum coating. In addition, the thermal resistance capability of molybdenum is better than that of phosphorus, which might also contribute to the high wear resistance to electric ablation.

Superficial cervical scar endometriosis following cone biopsy

Background: Cervical cone biopsy is a common simple surgical procedure for cervical intraepithelial neoplasia and cervical microinvasive carcinoma, with post-surgical bleeding being a common complication. ----Case Report: A 30-year-old woman with a history of cone biopsy two years prior complained of cyclic genital bleeding during the luteal phase of menstruation for more than a year. She was diagnosed with cervical scar endometriosis after cone biopsy. Electric ablation suppressed her long-term atypical genital bleeding, which caused her discomfort. Conclusion: The authors treated a rare case of uterine cervical endometriosis after cone biopsy. We should consider ectopic scar endometriosis during the differential diagnosis of atypical bleeding in women who have had a cone biopsy.

Activation of Anti-tumor Immune Response by Ablation of HCC with Nanosecond Pulsed Electric Field.

Locoregional therapy is playing an increasingly important role in the non-surgical management of hepatocellular carcinoma (HCC). The novel technique of non-thermal electric ablation by nanosecond pulsed electric field has been recognized as a potential locoregional methodology for indicated HCC. This manuscript explores the most recent studies to indicate its unique anti-tumor immune response. The possible immune mechanism, termed as nano-pulse stimulation, was also analyzed.

Electric Ablation with Irreversible Electroporation (IRE) in Vital Hepatic Structures and Follow-up Investigation

Irreversible electroporation (IRE) with microsecond-pulsed electric fields (μsPEFs) can effectively ablate hepatocellular carcinomas in animal models. This preclinical study evaluates the feasibility and safety of IRE on porcine livers. Altogether, 10 pigs were included. Computed tomography (CT) was used to guide two-needle electrodes that were inserted near the hilus hepatis and gall bladder. Animals were followed-up at 2 hours and at 2, 7 and 14 days post-treatment. During and after μsPEF ablation, electrocardiographs found no cardiovascular events, and contrast CT found no portal vein thrombosis. There was necrosis in the ablation zone. Mild cystic oedema around the gall bladder was found 2 hours post-treatment. Pathological studies showed extensive cell death. There was no large vessel damage, but there was mild endothelial damage in some small vessels. Follow-up liver function tests and routine blood tests showed immediate liver function damage and recovery from the damage, which correlated to the pathological changes. These results indicate that μsPEF ablation affects liver tissue and is less effective in vessels, which enable μsPEFs to ablate central tumour lesions close to the hilus hepatis and near large vessels and bile ducts, removing some of the limitations and contraindications of conventional thermal ablation.

The preparation and research of alumina powder by the electrical discharge machining method

Ultrafine alumina powder was prepared through the method of electric spark plasma ablation and a study was carried out by means of X-ray diffraction, scanning electron microscopy, energy spectrum analysis and laser particle size analysis. The following conclusions were drawn: the alumina can be prepared by spark, which gives an upper layer powder and lower layer coarse powder. Upper powder is mainly γ-alumina and α-alumina, and a small portion of residual aluminium, and the particle size is a few tenths of a micrometre. Lower coarse powder is mainly two kinds of α-alumina and more residual aluminium, having a particle size of several tens of micrometres. Upper powder will be reunited, because of the presence of aluminium hydroxide powder that makes the alumina particles stick together. The thickness of the rod, pulse width and pulse interval may affect particle size.

Ablation of rat substantia nigra is a good acute model of Parkinson's disease for cell transplantation therapy

WCN 2013 No: 1235 Topic: 2 — Movement Disorders Ablation of rat substantia nigra is a good acute model of Parkinson's disease for cell transplantation therapy S.-I. Hirano, Y. Tokumoto, Y. Nishikawa. Physiology, Osaka Dental University, Osaka, Japan; Tissue Engineering & Cell Therapy, Institute of Biomedical Research & Innovation, Kobe, Japan; Biochemistry & Integrative Medical Biology, School of Medicine, Keio University, Tokyo, Japan A valuable rat model of Parkinson's disease (PD) to study cell therapy was established. Forty-five female rats were examined. Using a stereotactic technique, we created an acute model of PD by highfrequency electric ablation of bilateral substantia nigra pars compacta. The ablation probe used was a 100 mm-long rigid bipolar needle electrode (1.0 mm in diameter). The rats developed persistent symptoms of PD, especially akinesia and postural instability. We tried all sorts of surgical protocols. The size and shape of the lesion that were ablated in a typical setting were evaluated. Then we determined that the optimal surgical parameter to place a lesionwas 1 Wof power for 15 s. The longterm viability of transplanted neural stem/progenitor cells was also examined and confirmed to be viable for more than 60 days following surgery. As the animal model was designed to suit the study of cell transplantation therapy, it did not utilize neurotoxic chemicals to make lesions and could avoid the harmful effects of them. The benefits of our ablationmodel of PDwere the rapidity and uniformity of appearance of the characteristics of Parkinsonism. Therefore we can identify the onset of PD strictly. This feature is a unique merit that is not shared by the othermethods. The technique described heremay provide a good acute model of PD for the research of intracerebral cell transplantation. This model will contribute to the progress in the field of cell transplantation therapy. doi:10.1016/j.jns.2013.07.414 Abstract — WCN 2013 No: 1201 Topic: 2 — Movement Disorders Distribution of wild and mutant torsinA in living cells WCN 2013 No: 1201 Topic: 2 — Movement Disorders Distribution of wild and mutant torsinA in living cells I. Toyoshima, E. Abe, S. Kamada. Neurology, Akita National Hospital of NHO, Yurihonjo, Japan; Neurology, Akita University School of Medicine,

A new technology for forming highly developed aluminum surface by electric pulse ablation

A novel polymeric composite whose conducting domains in the course of electric pulse treatment transfer onto an aluminum surface the microrelief information in the form of roughness was suggested. The degree of roughness is larger than 9.0 μm, exceeding by a factor of approximately 200 the aluminum surface roughness before ablation (R a = 9.42 μm, roughness coefficient K = 16.69, profile height along the base length from 5 to 70 μm). Analysis of 3D scans and profilograms of the aluminum plate surface after the ablation allows choice of methodological and technological approaches to the formation of the developed surface topology by this procedure.

Abstract 5387: Exploring effects of nanosecond and microsecond pulsed electric field ablation in a rat orthotopic hepatocellular carcinoma model

Abstract Hepatocellular carcinoma (HCC) is the third most common cancer in the world. A diagnosis of HCC carries a guarded prognosis, especially when metastasis is documented. Reliable, curative treatment for very early, early, and intermediate stages is still an inconsistent ideal. Nanosecond (ns), or microsecond (μs) pulsed electric fields (PEFs) that produce irreversible electroporation (IRE) could be used to ablate local tumor masses through minimal invasive or open surgery delivery. Both nsPEFs and μsPEFs induce permanent permeabilization of cells resulting in cell death without any thermal effect. NsPEFs can also impact intracellular organelles and induce apoptosis. Previous studies indicated under certain condition, there was a protective tumor response following nsPEFs treatment in mouse subcutaneous HCC model. In these studies, we specifically test the efficacy of nsPEFs and μsPEFs in an orthotopic HCC rat tumor model. N1S1 cells stably transfected with luciferase were used to generate tumors. Orthotropic insertion of transfected N1S1 HCC cells in Sprague Dawley rat livers was used as the model. Different pulses numbers, rise times and pulse durations were applied. The effect on treated tumor tissue suggests that a single treatment of 500 or 1000 100ns pulses with either slow (50ns) or fast (10ns) rise times and 50 kV/cm can eliminate HCC tumors. Continuous delivery of eighty 100μs microsecond pulses at 2.5 kV/cm dramatically reverses lesion enlargement. 1000 pulses of 100 ns PEFs with fast rise times provoke an innate immune response. Immune responses in this orthotopic HCC model are still under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5387. doi:1538-7445.AM2012-5387

Abstract No. 13: Bimodal electric tissue ablation (BETA): In-vivo porcine studies showing its effect on ablation zone size

Abstract No. 13: Bimodal electric tissue ablation (BETA): In-vivo porcine studies showing its effect on ablation zone size

Bimodal Electric Tissue Ablation (BETA)—Effect of Reversing the Polarity of the Direct Current on the Size of Ablation

Bimodal electric tissue ablation (BETA) is a new technique that uses the direct current in electrolysis to improve the efficacy of radio frequency (RF) ablation. It was hypothesized that attaching the cathode of the electrolytic circuit to the RF electrode will increase the tissue hydration, therefore delaying tissue desiccation during ablation. Consequently, the ablation process can continue for a longer period of time and produce larger ablations. This hypothesis was tested by reversing the polarity of the electrolytic circuit, which theoretically would cause tissue desiccation and therefore produce smaller ablations. This new setup is called reversed polarity bimodal electric ablation (RP-BEA). Three types of ablations standard radiofrequency ablation (RFA), BETA, and RP-BEA) were tested in a pig liver model. In BETA and RP-BEA, 9 V of direct current were provided for 10 min, after which the rf generator were switched on and both electrical circuits allowed to run concurrently. In all three setups, ablations were continued until "roll-off." The size of ablation was measured and compared with each other. The duration of ablation was significantly shorted in RP-BEA compared with standard RFA and BETA (48 s verus 148 s and 84 s, respectively, P = 0.004). The sizes of ablations in RP-BEA were also significantly smaller compared with standard RFA and BETA-skin. RP-BEA caused tissue desiccation resulting in a shorter duration of ablation and smaller ablations. Therefore, the theory that BETA increases ablation size due to the effects of increased tissue hydration around the rf electrode is correct.

Laparoscopic assisted endorectal pull-through with posterior sagittal approach to the repair of postoperative rectourethral and rectovaginal fistula

Rectourethral or rectovaginal fistula is a troublesome complication after anorectal surgery. The pelvic and perineal dissection may be difficult because of severe fibrosis adhesion around the fistula. The authors applied a novel technique: a combined laparoscopic assisted abdominal and posterior sagittal approach (PSA) to perform the redo surgery. Three boys and two girls (3-13 years old): case 1 had rectovaginal fistula after rectal dialation and modified Swenson's procedure; case 2 had rectovestibular fistula after twice perineal anorectoplasty; case 3 had rectourethral fistula after twice anorectoplasty; case 4 was imperforate anus with Hirschsprung's disease and rectourethral fistula that had been misdiagnosed; case 5 had rectourethral fistula after abdominoperineoanoplasty and Mollard procedure and posterior sagittal anorectoplasty. Laparoscopic assisted abdominal dissection was done first to mobilize the colon as far as the mid pelvis, and the normal colon was marked with a suture. The lower pelvic dissection was performed through the posterior sagittal route, the proximal rectum was mobilized and servered, the distal rectum was left undisected, endorectal mucosectomy with electric ablation was performed, then the fistula was closed from inside the rectum, and the stump of the colon was pulled through the rectum, the stump and the dentate line were anastomosed extraanally. Colostomy was done in case 2 and case 5. The postoperative follow-up showed no recurrent fistula, and all patients had attained normal voluntary bowel actions, but one child had infrequent minor soiling. Laparoscopic assisted endorectal pull-through of the intact colon can offer precise dissection, minimal abdominal injure, and spare troublesome mobilization of the fistula, and can prevent the recurrent of fistula. Posterior sagittal approach provides a direct repair of the fistula and anastomosis.

Bimodal Electric Tissue Ablation-Modified Radiofrequency Ablation with a Le Veen Electrode in a Pig Model

Radiofrequency ablation (RFA) is a method of treating non-resectable liver tumors by use of a high-frequency alternating electrical current. Concerns have been raised as the local recurrence rates following treatment have been reported to be as high as 47%. The size of the ablation is limited by charring of adjacent tissues. It is hypothesized that by hydrating the liver, we can reduce charring, thus producing larger ablations, and that this can be achieved by addition of a direct electrical current to the electrical circuit. Using a pig model, standard RFA control ablations were created in the left lobe of the liver. Ablations using the modified circuit were created in the right lobe. At the end of the procedure, the pig was killed by lethal injection and the liver harvested. From the explanted liver, the diameter of each ablation was measured and the modified ablations were compared with controls using restricted maximum likelihood variance analysis. From 4 pigs, 14 controls and 12 modified ablations were produced. The mean diameter of the controls was 27.78 mm (+/- SE 3.37 mm). The mean diameter of the modified ablation was 49.55 mm (+/- SE 3.46 mm), which was significantly larger than the controls (P < 0.001). This study has shown that by modification of the standard RFA circuit with the addition of a direct electrical current, significantly larger ablations can be produced. By using this technique, the number of ablations required to treat one tumor would be less and it is anticipated this could reduce the rate of local recurrence.

A Practical Approach to Atrial Fibrillation

Management of atrial fibrillation is still an individualized proposition, requiring considerable clinical judgment to select the most effective means of controlling cardiac rate and rhythm and preventing thromboembolism and stroke. The advantages and disadvantages of electric shock cardioversion, catheter ablation, and several medicinal and mechanical agents are discussed.

Coronary sinus stenosis as a late complication of catheter ablation in Wolff‐Parkinson‐White syndrome

This report describes a patient who developed stenosis of coronary sinus and cardiac veins five years after application of electric shock currents to the posterior mitral annulus and posteroseptal region of the tricuspid annulus for ablation of a left posterior accessory pathway and a right posteroseptal accessory pathway. This is the first angiographic documentation of coronary sinus stenosis as a late complication of electric ablation of accessory pathway. Cathet. Cardiovasc. Diagn. 42:70–72, 1997. © 1997 Wiley-Liss, Inc.

Balloon electric shock ablation

Balloon electric shock ablation is a surgical technique that has been used for treatment of ventricular tachycardia. However, little is known about the energy requirements and precise electrode array best suited to achieve effective ablation of the target area while limiting injury to the surrounding myocardium. This study was designed to determine the effects of endocardial scar (often present at the "site of origin" of clinical ventricular tachycardia) on depth of ablation resulting from balloon electric shock ablation. A chronic canine model of endocardial scar (3.9 +/- 0.6 mm thick) was developed with the use of balloon electric shock ablation techniques. We compared depth of ablation achieved with balloon electric shock ablation with low-energy shocks (22 J per bead) in normal dogs versus those with chronic endocardial scar. No difference was found in depth of ablation in normal dogs and in the scar model (7.2 +/- 1.2 mm versus 6.2 +/- 1.0 mm). Depth of injury expressed as a percentage of wall thickness was not different in the two groups (61% +/- 11% versus 57% +/- 3%). We conclude that the presence of endocardial scar does not influence depth of injury resulting from balloon electric shock ablation. This data provides guidance for clinical application of the technique as a "closed heart" surgical approach for control of ventricular tachycardia. The data are also discussed in relation to energy levels currently used for direct current catheter ablation in patients with ventricular tachycardia.

Thoracoscopic management of recurrent or persistent pneumothorax

Eighteen patients with recurrent or persistent spontaneous pneumothorax who would normally have had a thoracotomy were managed by electric ablation of the blebs or bullae and concomitant infusion of tetracycline solution through a conventional thoracoscope. There were 11 male and 7 female patients aged between 17 and 38 years. Fourteen cases were successful and four failed. Follow-up periods for successful cases were from 6 to 22 months. No recurrence was seen. Thoracotomy was necessary in 4 cases. At operation there were no remaining blebs or bullae. The air leaks were from necrotic lung tissue which appeared to follow excessive electric cautery. Wedge resection of the necrotic tissue successfully controlled the air leak. We conclude that the thoracoscopic management of pneumothorax by electric ablation of blebs or bullae and infusion of tetracycline solution can avoid the need for thoracotomy in patients with recurrent or persistent spontaneous pneumothorax.