High-voltage Lead Research Articles

Feasibility of left bundle branch area defibrillator implantation using three-dimensional delivery systems and traditional high voltage leads

Abstract Background Left bundle branch area (LBBA) pacing is an innovative cardiac pacing technique that provides physiological stimulation, which is useful in patients affected by atrioventricular block (preventing pacing-induced cardiomyopathy), and could be an alternative strategy to traditional cardiac resynchronization therapy. Recently, Huybrechts el al. have reported a proof-of-concept study concerning left bundle branch area defibrillator (LBBAD) implantation, evaluating the feasibility of positioning a standard high-voltage (HV) lead by manually pre-shaped delivery systems to achieve LBBAD. No follow-up data were available because the leads were moved to standard positions after testing. Purpose This study aimed to assess the safety and feasibility of definitively implanting a traditional HV lead, using novel three-dimensional delivery systems, to stimulate the LBBA and the lead performance in 1-month follow-up. Methods This is a single-center, non-randomized, prospective study. The study population consisted of consecutive patients referred for an ICD implantation between September and October 2023. LBBAD was attempted by exploiting three-dimensional delivery systems to reach the target transseptal location. After positioning an active fixation HV lead in the LBBA, acute pacing measurements were collected. Defibrillation testing was performed using either patient-tailored (DeFT Response) or fixed-tilt waveform. Echocardiographic evaluation using speckle tracking was performed after implantation. A short-term follow-up was planned in order to verify the stability of electrical parameters in one month. Results LBBAD was performed in 9 consecutive patients (mean age 69±11 years, 56% male). The mean time to implant the HV lead was 20 minutes. The HV lead was successfully implanted in 100% of patients, reaching LBBA in 6 (67%) patients at the first attempt and in 3 (33%) at the second attempt. LBBA pacing exhibited a mean QRS duration and V6 R-wave peak time of 128±9 ms and 64±12 ms. Acute LBBA pacing threshold, R-wave amplitudes, and pacing/shock impedances were 0.88±0.22 V at 0.5 ms, 8.4±2.8 mV, and 637±210 Ω/ 75±20 Ω. The defibrillation test (78% patient-tailored and 22% fixed-tilt waveform) was successful in 6 (75%) of patients at the first shock (~22J) and in 2 (25%) at the second shock (~33J)(test aborted in 1 patient due to respiratory issues during sedation). The mean peak strain dispersion of 31.7ms confirmed global synchrony during pacing. The electrical measurements remained stable, and no lead-related complications were observed at 1-month follow-up. Conclusion We performed for the first time ever LBBAD definitive implantation. This study proves the feasibility and safety of using three-dimensional delivery tools for LBBAD procedures and shows optimal results at the implant for up to one month. Nevertheless, a larger and long-term evaluation is needed to evaluate the performance of LBBAD implants.

Design and Performance of Ultraviolet 368-nm AlGaN-Based Flip-Chip High-Voltage LEDs with Epitaxial Indium Tin Oxide/Al Reflective Mirror and Symmetry Electrode Arrangement

In this letter, we describe the design and fabrication of high-power AlGaN-based ultraviolet (UV) flip-chip high-voltage light-emitting diodes (LEDs) operating at 368 nm with an epitaxial indium tin oxide (ITO)/Al reflecting mirror and symmetry electrode layout. Metal-organic chemical vapor deposition (MOCVD) was used to grow an ITO thin film as a transparent electrode on the LED surface. At 365 nm, epitaxial ITO thin films exhibited a transmittance of up to 93.6%. Additionally, the epitaxial ITO/Al reflective mirror has a reflectance of 81.2% at 365-nm. To investigate the electrical characteristics, four types of HV-LED micro-cells were constructed with varying n-type mesa structures and p-type interconnect electrodes. We demonstrated a forward voltage (Vf) of 7.86 V at 350 mA with a 2 × 2 mico-cells high-voltage ultraviolet 368-nm flip-chip LED after optimising electrode structure and device process.

Double-switch switched-inductor converter with minimal switch voltage stress for renewable energy conversion

In recent years, based on the notion of switched-inductor, DC-DC converters have been used in various applications, including DC microgrids, renewable energy integration, and high voltage light-emitting diodes. This publication presents a unique double-switch switched-inductor converter with minimal switch voltage stress for renewable energy conversion. The suggested converter is formed from different design arrangements of the traditional switched-inductor converter to reduce voltage stress and increase performance. The converter's non-ideal model and several operation modes depending on inductor current characteristics and output voltage ripple are described. The suggested topology is extended to attain a more significant voltage gain. The design and comparison of the proposed converters with recent converters are discussed. Finally, experimental prototype results are presented for a load power of 500 W to validate the proposed converter configuration. The efficiency curve is shown for various power and input voltage conditions. The loss breakdown characteristics for a load power of 500 W are provided.

3 Boyutlu Özgün Tasarımı ile Çok Renkli LED Tabanlı Fototerapi Cihazı Üretimi

Jaundice is a condition that results from an increase in bilirubin level in the blood. Its prevalence in newborns is around 60-70%. When this temporary jaundice becomes pathological and left untreated, significant damages may occur such as brain damage, vision loss, lung and kidney dysfunction, and even death. One of the methods used for the treatment of jaundice is phototherapy. In this study, a design has been made with 3 foldable LED panels to increase the target area. In addition, high-voltage LEDs with blue-green white wavelengths were used. Thus, it was aimed to minimize the risks of nausea and dizziness caused by intense blue light. An automatic system has been achieved by using temperature and light intensity sensors. The system will warn the user at temperatures and light intensity that are harmful to the baby.

Metallization Reliability of GaN-Based High-Voltage Light-Emitting Diodes

Metallization Reliability of GaN-Based High-Voltage Light-Emitting Diodes

Research on Real-Time Infrared Image Fault Detection of Substation High-Voltage Lead Connectors Based on Improved YOLOv3 Network

Currently, infrared fault diagnosis mainly relies on manual inspection and low detection efficiency. This paper proposes an improved YOLOv3 network for detecting the working state of substation high-voltage lead connectors. Firstly, dilated convolution is introduced into the YOLOv3 backbone network to process low-resolution element layers, so as to enhance the network’s extraction of image features, promote function propagation and reuse, and improve the network’s recognition performance of small targets. Then the fault detection model of the infrared image of the high voltage lead connector is created and the optimal infrared image test data set is obtained through multi-scale training. Finally, the performance of the improved network model is tested on the data set. The test results show that the improved YOLOv3 network model has an average detection accuracy of 84.26% for infrared image faults of high-voltage lead connectors, which is 4.58% higher than the original YOLOv3 network model. The improved YOLOv3 network model has an average detection time of 0.308 s for infrared image faults of high-voltage lead connectors, which can be used for real-time detection in substations.

Extinguishment of hot cathode discharges by space-charge and surface magnetic effects

Emission characteristics of a directly heated, rod-shaped LaB6 hot cathode has been studied in a multi-dipole confinement device. It is found that contrary to predictions from the conventional space-charge limited emission theory, emission current is not simply limited to a maximum value but eventually extinguished by space-charge related effects. In addition, directional preference of electron emission towards the positive lead of the applied heating voltage can be visibly observed. Results suggest that thermionically emitted electrons trapped in the virtual cathode are pumped towards the high voltage lead of the applied heating, and that the magnetic effects for filament heating currents exceeding 50 A may be the underlying mechanism of extinguishment; that is, the gyromotion of surface emitted electrons for sufficiently great heating currents may prevent electrons from escaping the virtual cathode. Geometrical effects are also briefly discussed.

Study on the transformer insulation design and insulation margin verification under extremely cold conditions

Under extremely cold conditions, the property of insulation materials will change with the decreasing of the temperature. Therefore, the research on the dielectric property of insulation materials under unknown extreme cold conditions and the verification on the insulation margin of the insulation materials shall be conducted to ensure that the insulation margin of key transformer parts can meet operation requirements and to avoid the discharge or breakdown failures. The paper studies the main insulation of transformer winding, the insulation of high-voltage connection and the electric field distribution of high-voltage lead model under ambient temperature and low temperature conditions. In addition, the insulation margin curve of the transformer under different temperature conditions is obtained through breakdown characteristic experiment and simulation experiment.

Survival of patients with pacing-induced cardiomyopathy upgraded to CRT does not depend on defibrillation therapy.

Permanent right ventricular pacing (RVP) results in cardiac dyssynchrony that may lead to heart failure and may be an indication for the use of cardiac resynchronization therapy (CRT). The study aimed to evaluate predictors of outcomes in patients with pacing-induced cardiomyopathy (PICM) if upgraded to CRT. One hundred fifteen patients, 75.0 years old (IQR 67.0-80.0), were upgraded to CRT due to the decline in left ventricle ejection fraction (LVEF) caused by the long-term RVP. A retrospective analysis was performed using data from hospital and outpatient clinic records and survival data from the National Health System. The prior percentage of RVP was 100.0% (IQR 97.0-100.0), with a QRS duration of 180.0ms (IQR 160.0-200.0). LVEF at the time of the upgrade procedure was 27.0% (IQR 21.0-32.75). The mean follow-up was 980±522 days. The primary endpoint, death from any cause, was met by 26 (22%) patients. Age>82 years (HR 5.96; 95% CI 2.24-15.89; P=.0004) and pre-CRT implantation LVEF<20% (HR 5.63; 95%CI 2.19-14.47; P=.0003), but neither the cardioverter-defibrillator (ICD) implantation (HR 1.00; 95%CI 0.45-2.22; P=1.00), nor the presence of atrial fibrillation (HR 1.22; 95%CI 0.56-2.64; P=.62), were independently associated with all-cause mortality. Advanced age and an extremely low LVEF, but neither the presence of atrial fibrillation nor implanting an additional high voltage lead, influence the all-cause mortality in patients after long-term RVP, when upgraded to CRT.

High Voltage, Low Current High-Power Multichannel LEDs LLC Driver by Stacking Single-Ended Rectifiers with Balancing Capacitors

In this paper, a new LLC converter for series-connected, high-voltage LEDs is proposed. The proposed LLC converter consists of two stacked, single-ended rectifiers and one balancing capacitor, to compensate for the current deviation of two individual LED strings. The proposed LLC LED driver can use a diode with low voltage stress, even if the secondary LED is connected in series to have a high driving voltage. In addition, even if several series-connected LEDs are changed into two-stacked structures, the balancing capacitor can compensate for the current deviation of the two separated LEDs, as well as the difference in leakage inductance of the two stacked single-ended rectifiers. The balancing capacitor can be made equal to the voltage tolerance of the stacked, single-ended rectifier diodes. The proposed circuit can be easily extended to a series channel LED driver circuit, without increasing the voltage stress. To verify the characteristics and operation of the proposed LLC LED driver, a 260W high-power LED driver is implemented.

Электромагнитная совместимость электроустановок нетяговых потребителей и системы электроснабжения с высоковольтным питающим проводом

A procedure for calculating switching overvoltages, including those that occur when lightning currents discharge in a power supply system’s contact system with a high-voltage power lead, is substantiated. It has been found that the floor-mounted signaling arrangements can be protected from switching overvoltages in the power supply system with a high-voltage power lead (HVPL PSS) by connecting the contact system supports with a long grounding conductor laid in the ground and not connected with the railway. An algorithm for simulating the spectral composition of zero sequence phase voltage components in overhead power lines with the insulated neutral with respect to ground in the case of their location in the HVPL PSS electromagnetic influence zone and the presence of a zero sequence voltage filter (ZSVF). If the studied system does not contain a ZSVF, this results in a multifold increase of the power line zero sequence voltages, imbalance of the phase voltages, and the occurrence of interference both at the line beginning and end points. The use of filters made it possible to smooth and flatten the spectral composition of voltage and to minimize the effect of resonance phenomena at high frequencies.

High-Voltage AlInGaN LED Chips

A high-voltage light-emitting diode (LED) flip chip based on an AlInGaN heterostructure is developed and fabricated. The LED flip chip consists of 16 elements connected in series, each of which is a convential LED. The chip with a total area of 1.25 × 1.25 mm is intended for a working current of 20 mA and a forward voltage of 48 V. To improve the current-distribution uniformity over the active region of the chip elements and to minimize the losses of the element area occupied by the n-type contact, the n-type contact pads in them are arranged inside the p-type contact region due to the two-level metallization layout with an intermediate insulating layer of dielectric. The arrangement topology of the contact pads is developed using numerical simulation. An increase in the quantum efficiency of the chip is provided by the application of combinations of metals with a high reflectance at the LED emission wavelength, which are used when fabricating n- and p-type contacts as well as current-carrying strips.

Reliability of High-Voltage GaN-Based Light-Emitting Diodes

Reliability is important in evaluating semiconductor device quality, although reliability measurement and analysis procedures are complicated. A new type of light-emitting diode (LED), GaN high-voltage (HV) LEDs, is superior to traditional low-voltage LEDs owing to fundamentally higher lighting efficiency and a simpler driving circuit. Recently, HV-LEDs have received much interest, and related commercial devices have been developed. However, reports on HV-LED reliability are very rare. Therefore, herein, we conduct a systematic study of the reliability of commercial HV-LEDs. In current stress-accelerated lifetime testing experiments on HV-LEDs (50 V) for 2,000 h, the luminous flux of white LEDs was reduced by 2.5%–9% and the luminous efficacy by 2.7%–11.3% after aging. The forward voltage was increased, the blue- and yellow-light irradiations of white-light HV-LEDs were reduced, and the excitation efficiency of fluorescence powders was decreased. Detailed analysis is carried out on a sample exhibiting catastrophic failure. The abrupt drop in luminous flux noted can be attributed to cracking of the fluorescent layer and reduction of optical transmittance in the epoxy resin, rather than deterioration in the chip itself. Finally, an improved lifetime-prediction method based on Bayesian statistics is proposed. Compared to conventional lifetime-calculation methods, this method combines experimental data, the conventional model, and historical information rationally. Therefore, it provides lifetime prediction at a higher confidence level: the HV-LED lifetime is estimated as 18 517 h. The results reported can guide the design, manufacturing, and packaging of HV-LEDs, while the new lifetime-estimation method is valuable to reliability evaluation of power electronic devices in the semiconductor industry.

Высоковольтные светодиодные кристаллы AlInGaN

AbstractA high-voltage light-emitting diode (LED) flip chip based on an AlInGaN heterostructure is developed and fabricated. The LED flip chip consists of 16 elements connected in series, each of which is a convential LED. The chip with a total area of 1.25 × 1.25 mm is intended for a working current of 20 mA and a forward voltage of 48 V. To improve the current-distribution uniformity over the active region of the chip elements and to minimize the losses of the element area occupied by the n -type contact, the n -type contact pads in them are arranged inside the p -type contact region due to the two-level metallization layout with an intermediate insulating layer of dielectric. The arrangement topology of the contact pads is developed using numerical simulation. An increase in the quantum efficiency of the chip is provided by the application of combinations of metals with a high reflectance at the LED emission wavelength, which are used when fabricating n - and p -type contacts as well as current-carrying strips.

Highlights From the Circulation Family of Journals

Highlights From the <i>Circulation</i> Family of Journals

Incidence and Predictors of Perioperative Complications With Transvenous Lead Extractions: Real-World Experience With National Cardiovascular Data Registry.

Transvenous lead extraction is an integral part of management of patients with cardiovascular implantable electronic devices. Real-world incidence and predictors of perioperative complications in extractions involving implantable cardioverter-defibrillator leads have not been described in detail. Data from the National Cardiovascular Data Registry Implantable Cardioverter-Defibrillator Registry were analyzed. Lead extraction was defined as removal of leads implanted for >1 year. Predictors of major perioperative complications for all extraction procedures (11 304) and for high-voltage lead (8362, 74%), across 762 centers, were analyzed using univariate and multivariate logistic regression. Major complication occurred in 258 (2.3%) extraction procedures. Of these 258 with a complication, 41 (16%) required urgent cardiac surgery. Of these 41, 14 (34%) died during surgery. Among the total 98 (0.9%) deaths reported, 18 (0.16% of total) occurred during transvenous lead extraction. In multivariable logistic regression analysis, female sex, admission other than electively for procedure, ≥3 leads extracted, longer implant duration, dislodgement of other leads, and patient's clinical status requiring lead extraction (infection/perforation) were associated with increased risk of complications. Smaller lead diameter, flat versus round coil shape, and greater proximal surface coil area were multivariate predictors of major perioperative complications specific to high-voltage leads. The rate of major complications and mortality with transvenous lead extraction is similar in the real-world outcomes to that reported in recent single-center studies from high-volume centers. There is significant risk of urgent cardiac surgery, which carries a high mortality, and planning for appropriate cardiothoracic surgery backup is imperative.

A Comparative Study of GaN‐Based Direct Current and Alternating Current High Voltage Light‐Emitting Diodes

In this work, one type of direct current high voltage light‐emitting diode (DC‐HV LED) and six types of alternating current high voltage LEDs (AC‐HV LEDs) are demonstrated. Comparative current‐voltage (I–V) and light output power (LOP)‐current (L‐I) characteristics are performed between 24 V DC‐HV LED and 24 V AC‐HV LEDs with eight working cells. The AC‐HV LED has relatively larger wall‐plug efficiency (WPE) than DC‐HV LED over a current density range from 0 to 152 A cm−2. The effect of the layouts on the optical and electrical properties of AC‐HV LEDs is further investigated. Owing to larger heat dissipation area and fewer number of chips, our combined numerical and experimental results demonstrate that the AC‐HV LED I has a more favorable current spreading uniformity compared to other AC‐HV LEDs. In addition, it is found that the LOP of AC‐HV LEDs is dependent on both the number of working cells and the ratio of radiation area to total chip area. Larger ratio of light emission area to total chip area can be obtained by decreasing the area of rectifier cells. Therefore, in order to achieve a much higher LOP, AC‐HV LEDs have to be designed with smaller area of rectifier cells and with more working cells simultaneously.

Low-Flicker Lighting From High-Voltage LEDs Driven by a Single Converter-Free Driver

This letter reports the design and characterization of high-power flip-chip high-voltage light-emitting diodes (HVLEDs), driven by a single converter-free LED driver for a compact and low-flicker lighting system. The HVLED chips show small forward voltage variation, uniform light emission, good optical output linearity, and stable thermal performance. All these characteristics well satisfy the demanding requirements of the novel quasi-constant power control scheme adopted in the converter-free LED driver. After bonding 12 HVLED chips (60 LED cells in total) and a single driver onto a silicon carrier through metal bonding, a low lighting flicker of 15.2%~17% was demonstrated, showing great potential for high-quality illumination applications that require low flicker, high light output, and good thermal stability.

Risk score to assess mortality risk in patients undergoing transvenous lead extraction.

The main aim of this study was to assess 1-year mortality and its predictors in a cohort of patients who underwent transvenous lead extraction (TLE) procedure. Retrospective analysis of clinical characteristics and 1-year follow-up of patients referred for a TLE procedure in a single, high-volume center between June 2006 and October 2014 was performed. The studied population included 130 patients (82 males; mean age 64 ± 15 years) implanted with pacemakers (74%), implantable cardioverter defibrillators (15%), or cardiac resynchronization therapy defibrillator (11%). Indications for the extraction included infective endocarditis (40.5%), pocket infection (18.5%), and lead fault or failure (41%). Total radiological success rate was 90% while clinical success rate was 93.5%. The cumulative 1-year mortality was 28%. Mortality was higher in a group of older patients (94.4% vs 68%, P = 0.001) and those with chronic kidney disease (33.3% vs 4.3 %, P = 0.0002) as well as in patients after removal of high voltage lead (88.9% vs 26.3%, P = 0.01). Higher mortality was also related to infection as an indication for TLE (37.2% vs 13.5%, P = 0.002). Following these findings a new risk score model named IKAR (I = infective indications; K = kidney dysfunction; A = age ≥ 56; R = removal of high voltage lead) was constructed. Patients with IKAR score ≥3 points were characterized by 79% mortality as compared to 16% in those with a score 1-2 points. One-year mortality of patients undergoing TLE procedure can be predicted by using IKAR risk score.

Enhanced Light Extraction of High-Voltage Light Emitting Diodes Using a Sidewall Chamfer Structure

High-voltage light-emitting diodes (HV-LEDs) were prepared with 4 × 2 microcells. A novel technique for enhancing the light extraction of HV-LEDs by using wet-etched chamfer structures in the sidewalls of each cell is proposed. The thicknesses of the u-GaN layers used were in the range of 3–7 μ m. Simulations revealed that the light extraction of the HV-LEDs with chamfer structures would be enhanced by increasing the u-GaN thickness. The output power (@80 mA) of the HV-LEDs without chamfer structures was 538.0–539.1 mW. However, the output powers (@80 mA) of the HV-LEDs with chamfer structures and u-GaN thicknesses of 3, 5, and 7 μ m were increased to 555.3, 573.1, and 561.6 mW, respectively. The 7 μ m thick u-GaN layer led to an extremely large thickness of the HV-LED epitaxial structure, which caused difficulties during the wet etching process. Because of the apparent decrease in the wet etching rate of GaN, the damages to the epitaxial structures of the HV-LED with the 7 μ m thick u-GaN was more obvious. Therefore, the device's light extraction was slightly reduced. The results confirm that chamfer structures are highly useful for improving the performance of HV-LEDs, especially for the u-GaN thickness of 5 μ m.