Bipolar Loop Research Articles

Improving omnipolar electrogram reconstruction: an animal model study

Abstract Background Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide. The characterization of cardiac tissue's electrophysiological substrate is crucial for the diagnosis and treatment of these conditions. High-density (HD) electrode arrays, such as the Advisor™ HD Grid Mapping Catheter and Sensor Enabled™ (SE), are commonly used to examine cardiac tissue locally and create activation maps. However, the current method for reconstructing omnipolar EGMs, a novel technique claimed to be orientation-independent, has limitations. The enhancement of this reconstruction methodology has the potential to improve the accuracy and reliability of electrophysiological mapping. This, in turn, can have a positive impact on patients suffering from cardiac arrhythmias, ultimately leading to better clinical outcomes. Purpose We propose a novel reconstruction method to estimate omnipolar EGM that overcomes the angle dependence weakness of the current method to enhance the reconstruction of electrophysiological signals. Methodology Prior experiments were conducted on isolated rabbit hearts using a 128-electrode array with electrodes spaced 1mm apart over the ventricular epicardium. Four-electrode cliques were designed from these experiments, with different inter-electrode distances as depicted in Figure 1A, to reconstruct the current and novel omnipolar configurations. Metrics were designed to assess the quality of the electrogram signals, including the bipolar loop area and the ratio of the bipolar components of the omnipole (see fig. 2). The bipoles were calculated from unipolar electrograms, and the signal was corrected with a 45º offset in the cross. The propagation angle was then detected, and the local activation time (LAT) was estimated. Results In the bipole plots, it was observed that the morphology of the bipolar loop becomes distorted with an increase in the inter-electrode distance, becoming thinner for distances less than 2mm. There is a direct relation between the areas in the bipolar loop and the inter-electrode distance (see Figure 2A). Furthermore, the values of the area in the cross are always comparable to the best-performing triangular clique. For the ratio of bipoles, the relation is inversely related to distance (see Figure 2B). Similarly, the performance of the cross is comparable to the best-performing triangular omnipole. Conclusion This study highlights the importance of accurate reconstruction of omnipolar EGMs for the diagnosis and treatment of cardiac arrhythmias. To achieve precise reconstruction, inter-electrode distances smaller than 2mm are recommended. The proposed reconstruction method based on the cross configuration is more accurate and robust to wavefront propagation, provided that the recommended distance criterion is met. This study opens up new possibilities for the design of new devices and practices in the clinic.Figure 1Figure 2

Magnetohydrodynamics simulation of magnetic flux rope formation in a quadrupolar magnetic field configuration

Magnetic flux ropes (MFRs) play an important role in high-energetic events like solar flares and coronal mass ejections in the solar atmosphere. Importantly, solar observations suggest an association of some flaring events with quadrupolar magnetic configurations. However, the formation and subsequent evolution of MFRs in such magnetic configurations still need to be fully understood. In this paper, we present idealized magnetohydrodynamics (MHD) simulations of MFR formation in a quadrupolar magnetic configuration. A suitable initial magnetic field having a quadrupolar configuration is constructed by modifying a three-dimensional linear force-free magnetic field. The initial magnetic field contains neutral lines, which consist of X-type null points. The simulated dynamics initially demonstrate the oppositely directed magnetic field lines located across the polarity inversion lines (PILs) moving towards each other, resulting in magnetic reconnections. Due to these reconnections, four highly twisted MFRs form over the PILs. With time, the foot points of the MFRs move towards the X-type neutral lines and reconnect, generating complex magnetic structures around the neutral lines, thus making the MFR topology more complex in the quadrupolar configuration than those formed in bipolar loop systems. Further evolution reveals the non-uniform rise of the MFRs. Importantly, the simulations indicate that the pre-existing X-type null points in magnetic configurations can be crucial to the evolution of the MFRs and may lead to the observed brightenings during the onset of some flaring events in the quadrupolar configurations.

Bipolar Transurethral Resection of Intravesical Fungal Bezoar Containing Multiple Multidrug Resistant Bacteria in a Chronic Catheter-Dependent Patient

Fungal bezoar is a very rare clinical entity that usually results from fungemia because of uncontrolled diabetes mellitus or immunosuppression. Most cases present in the upper urinary tract, but there have been less than 10 reported as presenting primarily in the bladder. Treatment is largely medical with antifungal therapies with no documented cases of concomitant bacterial colonization. Rarely, surgical intervention is warranted, but there are no documented surgical approaches with a bipolar cautery loop resectoscope. We present a case of a fungal bezoar of the bladder that was treated with transurethral resection. The presence of multidrug-resistant organisms resulted in postoperative sepsis controlled with intravesical and intravenous antibiotics and fluid resuscitation.

Study of the omnipolar EGM reconstruction for robustness against wavefront propagation in epicardial signals

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): National Research Program, Ministerio de Ciencia e Innovación, Spanish Government, Instituto de Salud Carlos III. Background Characterisation of electrophysiological substrate is commonly performed by examining cardiac tissue locally by using high-density (HD) arrays of equispaced electrodes – e.g. Advisor™ HD Grid Mapping Catheter, Sensor Enabled™ (SE). These allow creating activation maps of local tissue and substrate exploration. Recently, a novel operation mode arouse: the omnipole, which overcomes many limitations of bipolar and unipolar electrograms, as they are claimed to be orientation independent. Nevertheless, the current technique to reconstruct omnipolar EGMs has pitfalls as the estimation of some incidence angles of the propagation wavefront. We propose a novel reconstruction method to estimate omnipolar EGMs which overcomes the angle dependence weakness of the current one, providing a more robust EGM representation. We hypothesise that this technique will improve reconstruction of electrophysiological signals. Methods Prior electrophysiological experiments on isolated rabbit hearts were used [1], including recordings with a 128-electrode array 1mm apart over ventricular epicardium at 37ºC, with bipolar electrode stimulation. Four-electrodes cliques were designed from these experiments, with different inter-electrode distances as depicted in fig. 1A, reconstructing the current, and novel omnipolar configuration. Metrics to assess the quality of the EGM signals were designed, including the bipolar loop area, and the ratio of the bipolar components of the omnipole (ox and oy) – see fig. 1B. The bipoles were calculated from unipolar EGMs, the signal was corrected with the 45º offset in the cross, the propagation angle was then detected, and the local activation time (LAT) was estimated. Results In the bipole plots, it was observed that the morphology of the bipolar loop gets distorted with an increase in the interelectrode distance – thinner for distances <2mm. There is a direct relation between the areas in the bipolar loop and the inter-electrode distance (see fig. 2A). Furthermore, the values of the area in the cross are always comparable to the best performing triangular clique. For the ratio of bipoles, the relation is inversely to distance (see fig. 2B), similarly, the performance of the cross is comparable to the best performing triangular omnipole. Conclusion For reconstructing omnipolar EGMs, inter-electrode distances smaller than 2mm should be employed. Furthermore, if that condition is satisfied, the novel omnipolar reconstruction method proposed based on the cross configuration is more accurate and robust to wavefront propagation, given that the omnipolar EGM performs similarly or better than the best triangular configuration – and which triangle is fixed for the whole procedure, being the current reconstruction method less robust. Thus, a new standpoint to omnipolar reconstruction in high density electrode catheters is open, towards the design of new devices, and the practice in the clinic.

Novel reconstruction technique of omnipolar signals in high density electrode arrays

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): National Research Program, Ministerio de Ciencia e Innovación, Spanish Government; Instituto de Salud Carlos III. Background Novel multi-electrode array catheters with equidistant spacing between the electrodes, have emerged in recent years - e.g. Advisor™ HD Grid Mapping Catheter, Sensor Enabled™ (SE). These systems typically use unipolar signals, sensitive to low-frequency noise, and bipolar signals - highly dependent on the direction of propagation. Thus, the full potential of these new devices is not yet fully exploited. We hypothesise that, a new clique (4-electrode in a squared 2x2 matrix) configuration for the computation of omnipolar signals allows to take full advantage of novel multi-electrode catheters, more robust to the direction of propagation of the wavefront against the one currently proposed in literature – thus helpful in the clinic given the challenging positioning of the catheter in the heart cavity during electrophysiologic studies. Methods In the current 3-electrode clique, the centre of the signal obtained does not correspond to the centre of the area of the clique, being less robust to wavefront propagation direction (see fig. 1A). A new configuration, the cross clique, is proposed for calculating the electrogram to improve the robustness and reduce the errors in the estimation local activation time (LAT) and others – see figure 1. One thousand simulated signals with stratified propagation angles and variable parameters were implemented to emulate flat waves and homogeneous propagation over cardiac tissue. The methods used to calculate the signal with the proposed shape are: obtaining the bipoles, 45 degree correction of the signal, detection of the propagation angle, rotation of the detected angle and estimation of the LAT. Results The average amplitude of the bipolar loop increased from the old triangular clique configuration: 600.36 ± 116.40 mV; to the novel one cross-clique: 840.47 ± 160.09 mV. Regarding the local activation time estimation, a decrease in the error is observed from the current omnipolar reconstruction: 207.50 ± 256.91 μs, to the one proposed 22.75 ± 29.426 μs. When the bEGM propagation angle estimation is activated, the angle estimation error is 2.77 ± 25.26o for the current reconstruction method, in contrast to 1.09 ± 11.35o in the proposed one – see figure 1B. Conclusion Our novel configuration considerably reduces the LAT estimation error and, on average, captures a larger signal amplitude than the classic triangular clique method. Thus, it allows using the full potential of new catheters, improving the omnipolar analysis. hen applying automatic angle detection to the methods, in the case of the traditional method, it is influenced by the desynchronisation of the components of the traditional model as it widens the bipolar EGM loop – see figure 1.B. Thus, a novel omnipolar reconstruction method is proposed to better estimate intracardiac EGMs, more robustly against the direction of the wavefront propagation. Further studies are under consideration with clinical signals.

Cystoscopic removal of transvaginal mesh: Long-term outcomes.

This study's aim is to evaluate the long-term quality of life and functional outcomes following cystoscopic excision of stress urinary incontinence (SUI) and pelvic organ prolapse (POP) mesh extruded into the urinary tract in women. A retrospective chart review was performed of all cases of cystoscopic removal of extruded mesh at our high-volume tertiary care centre between April 2013 and August 2021. Postoperative patient-reported outcomes were collected via questionnaires: Urogenital Distress Inventory Short Form (UDI-6), EQ-5D-5L Visual analogue scale, ICIQ-Satisfaction (ICIQ-S) and additional questions regarding postoperative sexual function. During the study period, 27 women with a median age of 61 years (45-87) underwent cystoscopic mesh removal surgery using either Ho-YAG laser (56%) or bipolar loop resection (44%). The most common presentation of mesh extrusion was recurrent urinary tract infections (67%). Other presenting complaints were pain (41%), urinary urgency ± incontinence (41%) and voiding difficulties (18%). Long-term follow-up outcomes from 20 patients (median follow-up: 24 months) showed that mesh removal was rated successful by 80%, and 100% would choose to have the surgery again if in the same situation. Recurrent SUI was reported by 45% of respondents, and urinary urge incontinence was found in 50%. For patients who answered the sexual function questions, 50% reported improved sexual function postmesh removal (6/12). Cystoscopic removal of extruded female SUI and POP mesh is associated with high patient satisfaction and low morbidity in appropriately selected patients at 2-year median follow-up. A patient-centred shared decision-making process is essential in counselling patients regarding options and expected outcomes following mesh removal surgery.

Nonelectric shaving of endometrial polyp by hysteroscopy - A new technique to eliminate thermal damage

ObjectiveTo present a new technique for complete endometrial polypectomy, using the bipolar loop hysteroscope, but without the activation of electrical energy, and follow its efficiency and safety for the patient. Study designThis is a prospective descriptive study conducted at a university hospital. Forty four patients were recruited to the study according to an intra uterine polyp diagnosed by transvaginal ultrasound (TVS). Out of them 25 really had an endometrial polyp which was inspected by hysteroscopy. Eighteen were at menopause age and seven in their reproductive age. The hysteroscopic removal of the endometrial polyp was performed using the operative loop resectoscope without using electricity, meaning by cold loop. We called this unique technique SHEPH: Shaving of Endometrial Polyp by Hysteroscopy. ResultsThe range age was 21–77 years old. All patients with apparently endometrial polyp, underwent a complete removal of the polyp which could be directly seen through hysteroscopy. No bleeding was seen in all cases. The other nineteen patients had normal uterine cavity, so a biopsy was taken according to the indication. The specimen from all cases were sent to histological evaluation. An endometrial polyp was histologically confirmed in all cases who underwent the SHEPH technique, while fragments of an endometrial polyp was revealed by histology in six cases from the group that had normal uterine cavity. No complications were noted for the short and long periods. ConclusionsNonelectric Shaving of Endometrial Polyp by Hysteroscopy (SHEPH technique) is a safe and effective procedure which allows the surgeon to achieve a complete endometrial polypectomy but without using electrical energy within the body of the patient. The technique which is easy to learn, is new and unique by eliminate thermal damage in a very common gynecologic indication.

A versatile power supply system for the central solenoid of the QUEST spherical tokamak

Here, a versatile power supply system, consisting of two current sources, insulated-gate bipolar transistor stacks, and a capacitor bank, is proposed for application in various operations of the QUEST spherical tokamak. The central solenoid coil in this system can carrying a maximum current and voltage of ±8 kA and ±375 V, respectively. In plasma start-up experiments based on ohmic heating through double flux swing, a plasma current of over 100 kA is stably obtained. Moreover, the feedback control of the thyristor power supply is utilized to control the plasma current, plasma shape, and position. The oscillating central-solenoid current applies a bipolar loop voltage at constant time intervals, and the capacitor bank discharge facilitates a co-axial helicity injection as well as amplifies the toroidal current.

Initial experience with surrounding en bloc transurethral resection of bladder tumor and simultaneous intravesical treating for non-muscle invasive bladder cancer

PurposeThe high recurrence rate after traditional transurethral resection of bladder tumor (TURBT) remains a challenge for management of non-muscle invasive bladder tumor (NMIBC). The aim of this study was to evaluate feasibility, efficacy and safety of surrounding en bloc resection using a general wire bipolar loop electrode and simultaneous intravesical chemotherapy.MethodsWe retrospectively analyzed data of 111 consecutive patients with NMIBC treated from June 2018 to December 2021. These patients underwent conventional TURBT and immediate intravesical chemotherapy (n = 45) or surrounding en bloc TURBT and simultaneous intravesical chemotherapy in the Urology Department of Harbin Medical University Cancer Hospital, The former and latter were defined as the conventional TURBT group and the surrounding en bloc TURBT group, respectively. All patients were followed up from 6 to 40 months, with an average of 24 months. Demographic characteristics, location and number of tumors, perioperative and postoperative data, pathological results and recurrence were documented.ResultsThere were no significant differences in clinicopathological data between the conventional TURBT group (n = 45) and the surrounding en bloc TURBT group (n = 66). Operative time and complications associated with TURBT were comparable in the two groups. Recurrent tumors were found during follow-up in 2 (3.0%) of 66 patients in the surrounding en bloc group and 9 (20%) of 45 patients in the conventional group (p < 0.05). Lower urinary tract symptoms developed in 2 (3.0%) of 66 patients after surrounding en bloc TURBT and in 11(24.4%) of 45 patients after conventional TURBT (p < 0.05).ConclusionSurrounding en bloc TURBT and simultaneous intravesical chemotherapy might significantly decrease the recurrence rate of NMIBC, and showed favorable safety and tolerability profiles. The general bipolar loop electrode was appropriate to complete the procedure.

Two Methods for Adenomyotic Cyst Excision

<h3>Study Objective</h3> The objective of this video is to demonstrate two techniques for hysteroscopic resection of adenomyotic cysts. <h3>Design</h3> N/A. <h3>Setting</h3> A patient desiring fertility presents for further evaluation. Imaging is notable for two fundal cysts on ultrasound consistent with adenomyosis. After informed consent is obtained, OR hysteroscopy is performed under ultrasound guidance. <h3>Patients or Participants</h3> One patient with adenomyotic cysts is highlighted. <h3>Interventions</h3> The patient is taken to the operating room and a 5.5mm rigid hysteroscope is advanced to the fundus under ultrasound guidance. After confirming the location of adenomyotic cysts via ultrasound, hysteroscopic scissors are used to open the cysts, with adenomyosis confirmed by release of chocolate brown fluid. Cyst walls are resected in their entirety, one sharply and one with bipolar loop. <h3>Measurements and Main Results</h3> Direct visualization of the endometrial cavity as well as intraoperative ultrasound confirm complete removal of adenomyotic cysts. Pathology of the cyst walls confirmed adenomyosis. <h3>Conclusion</h3> Hysteroscopic resection of adenomyosis is safe and effective in select patients with focal disease, allowing for targeted removal under direct visualization. Here we demonstrate two hysteroscopic techniques for resection of adenomyotic cyst wall: sharp dissection, and the bipolar loop electrode.

Hysteroscopic Resection of Retained Placenta Accreta

<h3>Study Objective</h3> To present surgical videos of a case of retained placenta accreta managed with two hysteroscopic resections, demonstrating the surgical technique and key steps, and to review the literature regarding hysteroscopic resection of placenta accreta. <h3>Design</h3> Case report and surgical video. <h3>Setting</h3> Tertiary care hospital. <h3>Patients or Participants</h3> One patient. <h3>Interventions</h3> 31 y/o G6P4, with a history of a vaginal delivery 3 months prior complicated by retained placenta and significant postpartum hemorrhage, presented with irregular bleeding and was found to have 6.4 cm of echogenic material with doppler flow within the endometrium on ultrasound. Findings and history were concerning for unrecognized placenta accreta that now was presenting with a significant amount of retained tissue. Due to desire for future fertility, hysteroscopic resection with a bipolar loop resectoscope was performed. A second hysteroscopy was performed over 3 months later to complete resection and lyse intrauterine adhesions. <h3>Measurements and Main Results</h3> Hysteroscopic resection of retained placenta was successful in removing the majority of the placenta after one procedure, with only 9 mm remaining 3 months post-procedure. Post-operative course was complicated by continued amenorrhea 3 months later, likely from intra-uterine adhesions. Second hysteroscopy was successful in removing adhesions and the remainder of the placenta, with no residual tissue on MRI post-operatively. Surgical techniques for both hysteroscopies are reviewed in the surgical videos. <h3>Conclusion</h3> Hysteroscopic resection of a large, retained placenta accreta is feasible and effective, though may require multiple procedures to complete. Synechiae formation is a possible complication post-operatively and preventative measures can be considered after resection.

Percutaneous methods for the treatment of urothelial tumors of the pyelocaliceal system (case report and literature review)

Urothelial carcinoma is one of the most common solid malignancies. Moreover, urothelial cancer of the ureter of a single kidney is a rare entity that requires nephron-sparing treatment and carries a high risk of postoperative recurrence. An analysis of the literature on this disease was conducted using the databases of PubMed, Scopus, and Web of Science for the period from 2011 to 2022. A clinical case of recurrence of urothelial cancer of the pyelocaliceal system of the kidney in a 73-year-old patient was presented. For the primary tumor, the patient underwent percutaneous laser en bloc resection on the narrow base of the tumor. In case of recurrence, given the acute angle of attack and the wide tumor base, bipolar loop resection became necessary. This clinical observation demonstrates the need for logistical equipment with laser, mono- and bipolar energy sources, and flexible nephroscopes for the most effective and personalized treatment.

Endoscopic laser en bloc removal of bladder tumor. Surgical radicality and improvement of the pathological diagnostic accuracy.

Bladder cancer is one of the most common tumors among the general population. The first surgical approach to the tumor is often the transurethral resection with monopolar or bipolar loop. Recently, laser energy has become an alternative for resection of small bladder tumor, because it allows to obtain high quality samples with the "en bloc" technique. Our study aims to show the results of endoscopic diode laser treatment of bladder tumor up to three centimeters in maximum diameter. 189 patients underwent "en bloc" resection with diode dual length laser (980 nm-1470 nm). Follow up was over 12 months. Patients age range was from 45 to 75 years. Maximum diameter of the lesions was 3.0 cm. For each patient, a cold forceps biopsy sample was performed. All samples collected presented detrusorial layer. Pathological exam showed: 28 (14.8%) Ta, G1-G2; 7 (3.7%) T3, G2-G3; 14 (7.4%) T1, G2-G3 and 140 ( 74.1%) Ta, G2-G3. No complications occurred during or after surgery. At a median follow-up period of 6 months, we had no recurrence in the previous site of tumor. In the follow up at 3/6/12 months in 4 cases we had recurrence in different sites of bladder wall. Laser "en bloc" resection is an effective, feasible, and safe treatment for bladder tumor. It could be a valid alternative to monopolar and bipolar resection in small bladder cancer treatment.

V09-02 THULIUM FIBER LASER FOR BLADDER LEIOMYOMA TREATMENT

You have accessJournal of UrologyCME1 May 2022V09-02 THULIUM FIBER LASER FOR BLADDER LEIOMYOMA TREATMENT Alim Dymov, Evgeny Shpot, Alexandra Proskura, Roman Sukhanov, Vladimir Lekarev, Temirlan Karakotov, Yuliya Lee, and Leonid Rapoport Alim DymovAlim Dymov More articles by this author , Evgeny ShpotEvgeny Shpot More articles by this author , Alexandra ProskuraAlexandra Proskura More articles by this author , Roman SukhanovRoman Sukhanov More articles by this author , Vladimir LekarevVladimir Lekarev More articles by this author , Temirlan KarakotovTemirlan Karakotov More articles by this author , Yuliya LeeYuliya Lee More articles by this author , and Leonid RapoportLeonid Rapoport More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002617.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Bladder leiomyomas are very rare, representing only 0.43% of all bladder tumors. Today the most common surgical treatment options for bladder leiomyoma are transurethral, open, laparoscopic and robotic resection. Due to very low incidence rate the assessment of efficacy and safety of different surgical techniques is yet to be done. We present a series of 6 cases of bladder leiomyoma treated with Thulium Fiber laser (TFL) en bloc resection. This report aims to investigate the feasibility, safety and efficacy of TFL en bloc resection for the treatment of bladder leiomyoma and to present our surgical technique. METHODS: From January 2019 up to present time 6 female patients with bladder leiomyoma (size 1.5 cm - 4.0 cm) underwent TFL en bloc resection. All surgeries were performed with regular laser resectoscope (Richard Wolf GmbH, Knittlingen, Germany; Karl Storz, Tuttlingen, Germany), 600 μm laser fiber and TFL («FiberLase» IRE-Polus, Russia) operating at wavelength 1.94 µm. Laser settings - 1 J, 10 Hz, 10 W. Two out of six resected tumors were morcellated, three were removed with a bipolar loop, and one 2 cm tumor was extracted with Allis clamp. Intra- and postoperative complications were evaluated. RESULTS: All tumors were resected as a whole. Mean operative time was 24 min (10 - 40 min). Mean catheter time was 28 hours (24 - 48 hrs), mean length of hospital stay was 76 hours (72 - 96 hrs). No bladder perforation, obturator nerve stimulation, significant bleeding and postoperative complications were recorded. Morphological examination of resected tissues confirmed leiomyoma. CONCLUSIONS: Based on our experience TFL en bloc resection is an effective and safe option for the surgical treatment of bladder leiomyoma. Moreover, it seems to provide fast recovery from the surgery. Source of Funding: None © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e805 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alim Dymov More articles by this author Evgeny Shpot More articles by this author Alexandra Proskura More articles by this author Roman Sukhanov More articles by this author Vladimir Lekarev More articles by this author Temirlan Karakotov More articles by this author Yuliya Lee More articles by this author Leonid Rapoport More articles by this author Expand All Advertisement PDF DownloadLoading ...

Necrosis zone depth after bipolar plasma vaporization and resection in the human prostate

ObjectivesTo compare the depth of thermal necrosis after use of bipolar resection and vaporization technique comparing intra-individually bipolar loop and bipolar button electrodes. MethodsTransurethral resection and vaporization of the prostate was performed in 55 male patients (260 specimens in total). In a standardized procedure, a bipolar resection loop was used for resection, and a bipolar button electrode was used for vaporization. Both electrodes were applied in each patient, either in the left or in the right lateral lobe. The depth of necrotic zones in the resected or vaporized tissue of each patient was measured in a standardized way by light microscopy. ResultsThe mean depth with standard deviation of thermal injury caused by the loop electrode was 0.0495±0.0274 mm. The vaporization electrode caused a mean thermal depth with standard deviation of 0.0477±0.0276 mm. The mean difference of necrosis zone depths between the two types of electrodes (PlasmaButton–resection loop) was −0.0018 mm (p=0.691). ConclusionFor the first time, we present directly measured values of the absolute necrosis zone depth after application of plasma in the transurethral treatment of benign prostatic hyperplasia. The measured values were lower than in all other transurethral procedures. Standardized procedures of measurement and evaluation allow a statistically significant statement that the low necrosis depth in bipolar procedures is independent of the applied electrodes.

A Modified Technique of Bipolar Loop Resectoscopic Slicing for Treating Submucous Fibroids With Enucleation Makes the Operation Safer.

Background: In this study, a modified technique of resectoscopic slicing with a common bipolar loop was introduced, which facilitated the complete removal of the submucous fibroid inside the uterine cavity without any novel equipment.Results: Compared with the classical technique, our modified procedure possessed a shorter operation time (22.9 ± 7.3 vs. 38.9 ± 13.0 min, p < 0.05) and a smaller distending media volume (1,495.6 ± 540.1 vs. 2,393.1 ± 719.4 ml, p < 0.01).Conclusion: As a result, the current study suggested that the enucleation of submucous fibroid under hysteroscopy could be achieved by using only the bipolar loop, which reduced the consumption for novel equipment and enhanced the safety of the technique.

Surgical Ablation of Permanent Atrial Fibrillation: Age, LV Dilatation, Obesity.

Although concomitant surgical ablation can help to reach freedom from atrial fibrillation (FREEAF) even in patients with permanent atrial fibrillation (AF), some cardiac surgeons hesitate to perform concomitant ablation to avoid perioperative risk escalation. Here, we investigated outcome and predicators of therapeutic success of concomitant surgical ablation in an all-comers study. Ablation-naïve patients with formerly accepted permanent AF (FAP, n = 41) or paroxysmal AF (parAF, n = 24) underwent concomitant epicardial bipolar radio frequency ablation and implantable loop recorder (ILR) at two surgical departments. Follow-up examination for 24 months included electrocardiogram, ILR readout, 24h Holter monitoring, echocardiography, and blood sampling. Eighty-six percent of parAF and 70% of FAP patients reached FREEAF (month 24). Mortality was low (parAF/FAP: 5.3 ± 0.2%/4.1 ± 0.3%; p < 0.05; EuroScoreII; 6.1 ± 0.7%/6.4 ± 0.4%, p = ns) and no strokes occurred. FREEAF induced atrial reverse remodeling (left atrial [LA] diameter: -6.7 ± 2.2 mm) and improved cardiac function (left ventricular ejection fraction [LVEF]: +7.3 ± 2.8%), while AF resulted in further atrial dilation (+8.0 ± 1.0 mm, p < 0.05) and LVEF reduction (-7.0 ± 1.3%, p < 0.05). Higher LV (odds ratio [OR]: 1.164) and LA diameter (OR: 1.218), age (OR: 1.180) and body mass index (BMI) (OR: 1.503) increased the risk factors of AF recurrence. Patients remaining in sinus rhythm (SR) demonstrated a decrease in BMI, while AF recurrence was associated with stable overweight. Further aging did not reduce FREEAF. Long-term SR is achievable by concomitant surgical ablation even in FAP patients. Therefore, it should be offered routinely. Obesity influences therapeutic long-term success but may also offer addressable therapeutic targets to reach higher FREEAF rates.

Voltage stability improvement of a bipolar DC system connected with constant power loads

The constant power loads (CPLs) in direct current (DC) power system have the potential to degrade the stability of the whole system. This paper proposed a virtual resistance damping method that improves the stability of the bipolar DC system connected with CPLs. At first, a stability criterion for the bipolar system is given. After that, a bipolar DC system based on a half-bridge voltage balancer (HBVB) is introduced and its small-signal model is derived. On this basis, a virtual resistance damping method, Capacitor-Parallel-Damping-Resistance (CPDR), is proposed and analyzed. Moreover, the Lyapunov stability theory is adopted to investigate the impact of unbalanced load on the system stability. It turns out that system stability is determined by the sum of the system output power. This conclusion can significantly reduce the complexity of the bipolar system stability analysis and control loop design. Finally, the simulations and experimentations are performed to verify the proposed idea in this paper.

Large strain and low hysteresis in (0.64-x) Bi0.5Na0.5TiO3- 0.36Sr0.7Bi0.2TiO3- x(K0.5La0.5)(Ti0.9Zr0.1)O3 piezoceramics

In this work, (0.64-x)Bi0.5Na0.5TiO3- 0.36Sr0.7Bi0.2TiO3- x(K0.5La0.5)(Ti0.9Zr0.1)O3 lead-free piezoceramics were designed and fabricated by a conventional solid-phase sintering process. It is found that large strains (0.33 %), low hysteresis coefficients (32 %), and large dynamic d33* (367 p.m./V) were obtained at x = 0.01. The large strain originates from the reversible transition of the relaxor to the long-range ferroelectric order in the electric field. When the ferroelectric and relaxor phases coexist in a proper ratio, they can provide a favorable condition for the easier movement of the domains and improve the strain properties. In addition, after 105 cycles, the bipolar strain loop of x = 0.01 content changed slightly, demonstrating excellent fatigue resistance. This work provides a new way to design piezoelectric ceramics with large strain and low hysteresis.

Characterization of micro-ZnO/PDMS composite structured via dielectrophoresis – Toward medical application

This paper proposed a new approach to achieve full characteristic of highly non-linear current density–electric field (J-E) curve, which depends on various key factors in terms of filler concentration, temperature, input voltage level, and structuration of ZnO particles (i.e. aligned or randomly dispersed). The homogeneity of particle distribution within the polymer matrix, together with the chain-like structure of the aligned composites elaborated with various ZnO volume fraction was verified via microscopic investigations. Numerical simulation was also conducted through COMSOL Multiphysics, giving an estimation of field distribution around ZnO phase. Experimental characterization in addition to analytical models was established using varying (sinusoidal) or direct current (DC) tests. The DC test was carried out in order to identify the conduction profile as well as the percolation threshold of ZnO samples. Temperature also has considerable influence on the switching field and the dielectric permittivity of the nonlinear composites. In the sinusoidal test, current discrimination was adopted using bipolar polarization loop, allowed the detailed quantification of conductivity values, while prediction in the capacitive current density enabled to distinguish the relative permittivity. These results demonstrated that the electrical properties of ZnO compound, such as conductivity and permittivity, substantially enhanced with the increasing filler content, especially when the samples were subjected to dielectrophoretic manipulation. Further analysis was carried out on sinusoidal unipolar polarization to predict the dielectric loss factor as function applied field. Finally, by playing on different pertinent parameters, it was possible to efficiently control the electric and mechanical characteristics of ZnO composite. Such properties are highly important in application of microvaristors used as protection devices. By associating with other features of ZnO like piezoelectricity, this material is undoubtedly of high interest in medical use where multifunctional system design becomes mandatory.