Electrical Instability Research Articles

Factors of Cardiovascular Risk in Drivers of Locomotive Crews of Railway Transport with Ventricular Arrhythmias

AIM: This study aimed to assess cardiovascular risk factors in drivers and assistant drivers of railway engine crews with ventricular rhythm disorders.
 MATERIALS AND METHODS: The study included 120 patients aged 39 to 61 years (mean age M SD: 50.4 4 years), who were distributed into two groups with and without ventricular rhythm disorders. All participants underwent 12-lead daily ECG monitoring with assessment of noninvasive markers of myocardial electrical instability (circadian profile, QT interval, late ventricular potentials, T-wave alternation, rhythm variability). Traditional factors of cardiovascular risk, the employment period in the profession, and the level of personal and situational anxiety on Spielbergers state-trait anxiety inventory (STAI) were evaluated.
 RESULTS: In Group 1, in comparison with Group 2, significant differences were revealed in the duration of the PQ interval (during the day and at night) and the indicators of late ventricular potentials (RMS 40 and TotQRSF). When analyzing risk factors, elevated indices of total blood cholesterol were registered in both groups, and the risk on the SCORE scale was at a moderate level. In the group of workers with ventricular rhythm disorders, higher indicators of total blood cholesterol and the frequency of smoking and alcohol consumption were established. In individuals with ventricular rhythm disorders, a significant relationship was detected between the number of registered single monomorphic ventricular extrasystoles and the age of the employee (r = 0.3, р 0.05), and blood pressure level (r = 0.3, р 0.05), and the relationship between the level of anxiety and the registration of single supraventricular extrasystoles was established (r = 0.3, р 0.05). In the Group 2, a significant correlation was revealed between the number of registered single supraventricular extrasystoles and age (r = 0.2, р 0.05), the employment period in the profession of a driver (r = 0.2, р 0.05), the blood pressure level (r = 0.2, р 0.05), and the level of anxiety on the STAI (r = 0.3, р 0.05).
 CONCLUSIONS: Drivers of railway engine crews with ventricular rhythm disorders are characterized by a higher level of total blood cholesterol and a higher frequency of smoking and alcohol consumption. They have significant changes in the duration of the PQ interval (during the day and at night) and indicators of late ventricular potentials (RMS 40 and TotQRSF) according to Holter monitoring. The relationship of the number of ventricular rhythm disorders with age and the office values of systolic and diastolic blood pressure is noted in drivers of engine crews of railway transport.

Heat Shock Protein 27 Levels Predict Myocardial Inhomogeneities in Hemodialysis Patients.

Background Sudden cardiac death (SCD) is the single major cause of death in hemodialysis (HD) patients. QRS-T angle is an established marker of global repolarization heterogeneity associated with electrical instability and SCD. Heat shock protein 27 (HSP27) plays an important, protective role against noxious factors in the cardiovascular (CV) system. This study is aimed at assessing whether low HSP27 is associated with myocardial inhomogeneities in HD patients, as expressed by increases in the spatial QRS-T angle. Methods Clinical data and biochemical, echocardiographic, and electrocardiographic parameters were evaluated in 182 HD patients. Patients were split into normal and abnormal QRS-T angle groups. Results Patients with abnormally high QRS-T angles were older and had higher prevalence of diabetes as well as myocardial infarction, higher left ventricular mass index (LVMI) and C-reactive protein, worse oxidant/antioxidant status, and lower ejection fraction and HSP27. Multiple regression analysis revealed that abnormal QRS-T values were independently, negatively associated with serum HSP27 and positively associated with LVMI. Conclusions Low HSP27 levels are associated with increased heterogeneity of myocardial action potential, as expressed by increased spatial QRS-T angle.

Heteroepitaxy of Hf0.5Zr0.5O2 ferroelectric gate layer on AlGaN/GaN towards normally-off HEMTs

Ferroelectric gate High Electron Mobility Transistors (HEMTs) stands out as a promising route for normally-off HEMTs. HEMTs based on perovskite ferroelectrics, however, suffer from low threshold voltage, electrical instability, and CMOS process incompatibility. In this work, fluorite Hf0.5Zr0.5O2 (HZO) was designed to serve as ferroelectric gate layer for normally-off HEMTs, and HZO/MgO/AlGaN/GaN/Si ferroelectric-semiconductor heterostructure was constructed by pulsed laser deposition. The epitaxial relationship was revealed to be [112¯](111) HZO//[112¯](111) MgO//[101¯0](0002) GaN, and corresponding domain matching mechanism was determined as 6aMgO=5aHZO. Strong coupling effect between ferroelectric polarization of HZO and two-dimensional electron gas (2DEG) at AlGaN/GaN interface was confirmed by continuous modulation of threshold voltage from −3.8 V to +3.2 V through regulating polarization state of 15 nm HZO. Moreover, relatively weak depolarization effect of HZO on AlGaN/GaN was observed, which was crucial for device electrical stability. In addition, ultrahigh threshold voltage of +5.5 V was detected in designed heterostructure with 50 nm HZO. Our work demonstrates that epitaxial HZO ferroelectric gate layer on AlGaN/GaN possesses high threshold voltage, good device electrical stability and great semiconductor process compatibility, emerging as great potential for developing and miniaturizing high-performance normally-off HEMTs.

QT interval instability and variability in dogs with naturally-occurring hypercortisolism.

Hypercortisolism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with naturally-occurring hypercortisolism (NOHC), indices of variability and instability of the QT interval were retrospectively studied in 38 dogs with NOHC and prospectively studied in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the NOHC group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. The NOHC group was subdivided according to cortisol suppression pattern in the low-dose dexamethasone suppression test. All electrocardiographic indices of partial and absent suppression patterns were numerically higher than healthy dogs. QTv and TI were lower in the control group than in both NOHC subgroups. LTI and STI were lower in the CG than in the group with the partial suppression pattern. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result might indicate that the etiology of NOHC, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term and the long-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.

Ventricular tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy: How to Manage?

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is a condition characterized by fibrofatty replacement of the RV myocardium due to genetic abnormality. Structural changes may be absent or minor in the early stages of the disease and be localized in a specific region of the RV. Clinically it appears as RV electrical instability. To reduce the risk of arrhythmic events or sudden cardiac death, device therapy and pharmacotherapy may be recommended. In this paper, we describe a case of a female with ARVC and a brief discussion based on a literature review. The patient presented with chest discomfort accompanied by palpitation. An electrocardiogram (ECG) showed ventricular tachycardia of RV apex origin, and convert to symmetric inverted T-waves and probable epsilon waves in the right precordial leads, mimicking a pseudo-right bundle branch block (RBBB) pattern following electrical cardioversion. The parasternal short-axis view of echocardiography shows severe right ventricular dilatation. Subsequent workup using CMR was planned but the patient refused. We diagnosed this patient with ventricular tachycardia on a background of suspicious arrhythmogenic right ventricular cardiomyopathy. We were able to provide accurate diagnosis and treatment, avoiding potentially fatal consequences. As a result, it is critical to recognize potential ARVC ECG findings and to know when to pursue further research and implement therapies.

New Strategy for Improved Conductivity and Redox-Enhanced Supercapacitor Performance of Nickel Metal-Organic Framework

Owing to the high-surface area and macromolecular architecture, metal-organic frame (MOF) material has been referred to as an advanced system for supercapacitor applications. Indeed, poor electrical property and structural instability under electrified conditions are the major limitations. In this work, we wish to introduce a new strategy for marked enhancement in the electrical and redox property of the MOF by simple chemical mixing followed by ultrasonication of pristine MOF with low-cost carbon black (CB) material. As a model system, Ni-MOF, prepared using 2,2’-bipyridine and benzene-1,4-dicarboxylic acid (provides a rich source for π-π interaction with graphic carbon), functionalized CB, designated as CB@Ni-MOF, has been developed for improved energy storage application. Electrochemical studies of CB@Ni-MOF modified screen-printed carbon electrode showed about ten times enhanced peak current and surface excess value (24.8 nmol.cm−2) over the respective pristine Ni-MOF modified electrode (1.9 nmol.cm−2) in 1 M NaOH solution. Physicochemical and electrochemical characterization using TEM, X-ray, Raman, FTIR, BET Surface area and electrochemical impedance measurements collectively revealed that there are multiple hydrogen-bonding interactions between the oxygen functional groups of Ni-MOF and CB, and strong π-π interaction between the aromatic units of Ni-MOF and sp2 carbon-graphitic sites of CB. These interactions help de-agglomeration and active-site inter-connection and a marked reduction in the multi-shell hollow structure of the CB (55nm→30nm). Capacitance measurement by galvanostatic charge and discharge (GCD) method yield value, 2700 F g−1 at a biased-current, 2 A g−1. It is about seven times higher than the values obtained with the respective pristine Ni-MOF (415 F g−1) and markedly higher than several literature-based MOF values. A GCD cyclic stability of the CB@Ni-MOF showed about 2% and 10% decrement at 2000 and 5000 cycles, respectively.

Short-coupled ventricular ectopics leading to cardiac arrest in a young woman

BackgroundThis case report highlights the importance of recognizing that ventricular ectopy may be a cause for syncope and sudden cardiac death, through triggered disorganized arrhythmia. In the context of syncope, ventricular ectopy should be carefully assessed for coupling interval and morphology.Case presentationA 39-year-old woman, who had presented with recurrent syncope, had a cardiac arrest shortly after admission that required emergency defibrillation. Review of her cardiac monitoring revealed an episode of polymorphic ventricular tachycardia which had degenerated into ventricular fibrillation. The dysrhythmia had been initiated by a short-coupled (R-on-T) ventricular ectopic (VE) beat. Anti-arrhythmic therapy was initiated in the form of hydroquinidine, but the patient continued to have frequent VEs of right bundle branch block (RBBB) morphology with a relatively narrow QRS complex and a variation in frontal axis. A cardiac MRI revealed late gadolinium enhancement of the posterior papillary muscle (indicative of focal scarring). The patient underwent electrophysiological mapping and catheter ablation of her ectopy. The patient made a good recovery and was discharged from hospital with a secondary prevention implantable cardioverter-defibrillator (ICD) in situ.ConclusionsShort-couped VEs that are superimposed onto the preceding T wave (R-on-T) are indicative of electrical instability of the heart and should prompt urgent investigation. By studying the morphologies and axes of the QRS complexes produced by VEs, we can identify their likely origins and ascertain their clinical significance.

Electric Field-Controlled Structural Instability and Mechanical Properties of Methane Hydrates

Electric Field-Controlled Structural Instability and Mechanical Properties of Methane Hydrates

Molecular genetic markers of QT interval duration and sudden cardiac death: literature review

The study of sudden cardiac death (SCD) and its etiopathogenesis in cardiology practice remains one of the most pressing public health problems. In Western countries, SCD accounts for 20% of the total mortality and 50% of mortality associated with cardiovascular diseases. Considering the electrical instability in the myocardium as one of the main reasons for the development of life-threatening arrhythmias (ventricular tachycardia / ventricular fibrillation) and SCD, one should be aware of such provoking factors as ischemic heart disease, myocarditis, valvular heart disease, pharmacological influences, cardiomyopathy, and channelopathy. An increase or decrease in the duration of the QT interval, which reflects the work of ion channels, as well as ventricular depolarization and repolarization, increases the risk of SCD.The aim of this review was to study and analyze the available literature data on the relationship of molecular genetic markers with the duration of the QT interval.Currently, there is a number of genetic studies that allow to identify a large number of mutations and polymorphisms of known genes that affect the variability of the QT interval, showing their significance in risk stratification of sudden arrhythmic death and choosing the right tactics for managing, preventing, and treating patients, thus reducing the risk of SCD. The predictive value of genetic testing is the highest for long QT syndrome (LQTS), for which a gene-specific risk profile has been established, and lower for other channelopathies. A large amount of genetic data may be a promising approach to quantifying the risk of SCD, especially at a young age, which will be facilitated by further study of this problem.

ANALYSIS OF THE OCCURRENCE OF VARIOUS CARDIOVASCULAR EVENTS IN PATIENTS WITH MYOCARDIAL INFARCTION WITHOUT ST SEGMENT ELEVATION DURING 6TH AND 12TH MONTHS

Myocardial infarction remains one of the leading causes in the structure of general and cardiovascular morbidity and mortality worldwide. Despite significant progress in the treatment of acute myocardial infarction in most developed countries, the emergence and prevention of early and late complications is of great interest. Existing unified methods of diagnosis and treatment of NSTEMI significantly avoid adverse events in the rehabilitation period of the disease, however, the long-term prognosis of this category of patients remains unfavorable due to the development of myocardial dysfunction after postinfarction remodeling and prognostic adverse arrhythmias. The search for opportunities to predict the development of complications, study of remodeling processes and their impact on the development of electrical instability of the myocardium, which is currently considered a promising area of non-invasive diagnosis of myocardial infarction. With regard to NSTEMI, the unfavorable long-term prognosis is primarily due to the development of myocardial dysfunction, electrical instability of the myocardium or the development of recurrent coronary events.
 Aim. To analyze the probability of occurrence of various cardiovascular events in patients with myocardial infarction without ST-segment elevation during 6 and 12 months of follow-up.
 Materials and methods. We conducted a comprehensive study of 200 patients with acute myocardial infarction without ST-segment elevation aged 38 to 80 (mean 62.0 ± 0.71, median 62 and interquartile range 55 and 70). A retrospective analysis of patients' condition during 6 and 12 months of follow-up was performed. Surveillance of patients was carried out in the mode of telephone contact with patients, assessment of the condition on scheduled visits (1st, 3rd, 6th and 12th month after hospitalization of patients with acute myocardial infarction) and recording of unscheduled and urgent requests of patients for medical help. We conducted a retrospective analysis of the condition of NSTEMI patients during 6 and 12 months of follow-up. Surveillance of patients was carried out in the mode of telephone contact with patients, assessment of the condition on scheduled visits (1st, 3rd, 6th and 12th month after hospitalization of patients with acute myocardial infarction) and recording of unscheduled and urgent requests of patients for medical help. During the observation of patients we recorded the cardiovascular events, such as cardiovascular death, myocardial infarction, stroke, heart decompensation, heart rhythm disorders.
 Results. Analysis of cardiovascular events observed during the year in the examined group of patients revealed that during the first year after an acute coronary event the most common complications were the development of acute decompensation of chronic heart failure, acute heart failure de novo and atrial fibrillation paroxysms de novo. To a lesser extent, events such as episodes of unstable angina, non-fatal myocardial infarction and strokes, and sudden cardiac death have been reported. Time dependence was demonstrated only for the first two, namely an increase in the frequency of complications at a later date – from the 6th to the 12th month compared to the first 6 months of follow-up.
 Conclusions. Manifestations of cardiac decompensation and arrhythmia in the delayed period of the disease are associated with manifestations of structural remodeling and electrical instability of the myocardium, while the reduction of fatal complications is a consequence of early invasive treatment strategy.

Tailoring the chemical heterogeneity of Mn-modified 0.75BiFeO3-0.25BaTiO3 ceramics for piezoelectric sensor applications

The Mn-modified 0.75BiFeO3-0.25BaTiO3 (75BFBTMn) piezoelectric ceramic possesses a high depolarization temperature of 500 °C and a large piezoelectric coefficient of 110 pC/N, showing the potential for high temperature piezoelectric sensors. However, 75BFBTMn ceramic usually suffers dielectric degradation and abrupt drop of piezoelectric coefficient in the range of 300 °C to 500 °C. Combined the high-energy synchrotron X-ray diffraction analysis with Backscatter-SEM results, it is demonstrated that the electrical thermal instability is owing to the existence of chemical inhomogeneity. The Air-annealing treatment is able to decrease the volume fraction of pseudo-cubic phase and the lattice distortion, removes the chemical inhomogeneity in the grain and free Bi2O3 at grain boundary, and then eliminates dielectric anomalies and piezoelectric degradation with temperature. These results indicate that air-annealing is a simple but effective method to eliminate the chemical inhomogeneity in 75BFBTMn ceramics, thereby improving the property thermal stability for high temperature piezoelectric sensor applications.

PECULIARITIES OF HEART RHYTHM DISORDERS AND VENTRICULAR REPOLARIZATION STATUS IN PATIENTS WITH MYOCARDIAL INFARCTION WITHOUT ST SEGMENT ELEVATION DEPENDING ON THE INDICATORS OF STRUCTURAL REMODELING OF THE LEFT VENTRICLE

Resume. Despite advances in the treatment of acute myocardial infarction in most developed countries, this pathology remains the leading cause of morbidity and mortality. The search for opportunities to predict the development of complications, study of remodeling processes and their impact on the development of electrical instability of the myocardium is currently considered as a promising area of ​​non-invasive diagnosis of myocardial infarction. Aim. To establish the features of cardiac arrhythmias and the condition of ventricular repolarization in patients with NSTEMI depending on the indicators of structural remodeling of the left ventricle. Materials and methods. We conducted a comprehensive study of 200 patients with NSTEMI aged 38 to 80 years. All patients were examined according to the current protocol of diagnosis and treatment of patients with acute coronary syndrome without ST-segment elevation and daily Holter ECG monitoring was performed for 3-5 days after hospitalization. Results. An increase in the left ventricular myocardial mass index and a change in the geometric model are associated with an increase in the probability of developing myocardial electrical instability, in particular extrasystoles of any topic and paroxysmal tachycardia. At the same time, changes in structural remodeling indicators did not reveal correlations with ventricular repolarization disorders in the early NSTEMI period. Conclusions. Evaluation of the indicators of structural remodeling of the ventricular myocardium in the early period of NSTEMI allows to predict the risk of electrical instability of the myocardium and to carry out appropriate preventive measures.

Immediate Versus Delayed Cardiac Catheterization in Post-Arrest Patients Without ST Elevation Myocardial Infarction: Is Survivorship Bias an Important Influence?: March 2022 Annals of Emergency Medicine Journal Club

Immediate Versus Delayed Cardiac Catheterization in Post-Arrest Patients Without ST Elevation Myocardial Infarction: Is Survivorship Bias an Important Influence?: March 2022 Annals of Emergency Medicine Journal Club

Ventricular conduction improvement after pericardial fat reduction triggered by rapid weight loss in subjects with obesity undergoing bariatric surgery.

Obesity is considered a major cardiovascular risk factor. The excess of pericardial fat (PF) in patients with obesity has been associated with a variety of electrocardiographic alterations. In previous studies, we demonstrated that rapid weight loss and bariatric interventions result in decreased PF. The aim of this study is to report the changes in PF after bariatric surgery and its effect on ventricular conduction. US hospital, academic institution. A linear measurement of PF thickness on computed tomography scans was obtained for 81 patients, as well as a retrospective review of electrocardiographic changes before and after bariatric surgery. We compared the changes in PF thickness and electrocardiographic components before and after procedures. Common demographics and co-morbidities were collected along with lipid profiles preoperative and postoperative. A total of 81 patients had electrocardiograms done before and 1 year after bariatric surgery. Females comprised 67.9% (n = 55), and the average age for our population was 55.07 ± 14.17 years. Pericardial fat thickness before surgery was 5.6 ± 1.84 and 4.5 ± 1.62 mm after surgery (P = .0001). Ventricular conduction (QT and QT corrected [QTc] intervals) showed a significant improvement from 438.7 + 29 before to 426.8 + 25.3 after bariatric surgery (P = .006). We found a statistically significant association between the decrease in PF and the decrease in QTc intervals (P = .002). Obesity is a risk factor for arrhythmias and sudden cardiac death. Bariatric surgery and its effect on PF produce an improvement in ventricular conduction, which may reduce the ventricular electrical instability in patients with obesity.

Large areal capacity all-in-one lithium-ion battery based on boron-doped silicon/carbon hybrid anode material and cellulose framework

Si, featuring ultra-large theoretical specific capacity, is a very promising alternative to graphite for Li-ion batteries (LIBs). However, Si suffers from intrinsic low electrical conductivity and structural instability upon lithiation, thereby severely deteriorating its electrochemical performance. To address these issues, B-doping into Si, N-doped carbon coating layer, and carbon nanotube conductive network are combined in this work. The obtained Si/C hybrid anode material can be “grown” onto the Cu foil without using any binder and delivers large specific capacity (2328 mAh g−1 at 0.2 A g−1), great rate capability (1296.8 mAh g−1 at 4 A g−1), and good cyclability (76.7% capacity retention over 500 cycles). Besides, a cellulose separator derived from cotton is found to be superior to traditional polypropylene separator. By using cellulose as both the separator host and the mechanical skeleton of two electrodes, a flexible all-in-one paper-like LIB is assembled via a facile layer-by-layer filtration method. In this all-in-one LIB, all the components are integrated together with robust interfaces. This LIB is able to offer commercial-level areal capacity of 3.47 mAh cm−2 (corresponding to 12.73 mWh cm−2 and 318.3 mWh cm−3) and good cycling stability even under bending. This study offers a new route for optimizing Si-based anode materials and constructing flexible energy storage devices with a large areal capacity.

Two-dimensional electronic structure for high thermoelectric performance in halide perovskite Cs2Au(I)Au(III)I6.

Pb- or Sn-based halide perovskites usually exhibit poor thermoelectric performance, arising from their low electrical conductivity or oxidation state instability. It is highly desired to search for new halide perovskites with good thermoelectric properties. In this work, the thermally stable mixed-valence halide perovskite Cs2Au(I)Au(III)I6 is revealed to be a highly promising thermoelectric material with high in-plane power factor and ultralow lattice thermal conductivity using first-principles calculations. The high in-plane power factor is achieved due to the novel two-dimensional electronic structure near the Fermi level driven by the weak interaction between AuI-5d and I-p orbitals. In addition, the small group velocities and short phonon lifetimes give rise to ultralow lattice thermal conductivity in Cs2Au(I)Au(III)I6. These excellent electronic and thermal properties lead to a high ZT value, which is close to 1 at 300 K and ∼4 at 800 K. Our results suggest that the 2D electronic structure from the weak interaction between d and p crystal orbitals is a promising route to design high-efficiency halide double perovskite thermoelectric materials.

The joint influence of normal vibrations and electric field on the stability of a two-layer fluid system

The article focuses on the joint influence of normal vibrations and normal electric field on the stability of a system consisting of two flat horizontal fluid layers. Two cases are considered. In the first one, the system is formed by two layers of dielectric fluids (both layers have the same thickness) and, in the second, the system includes a dielectric fluid layer and an ideal electrically conductive fluid layer. The results obtained for these two cases are qualitatively similar. We study two approximations: the low-viscosity approximation and high-frequency vibrations. For the low-viscosity approximation, the so-called electric instability mode and the resonant mode are analyzed. In this case, the short-wavelength and long-wavelength instability modes are considered. In the low viscosity approximation, there occurs a viscous boundary layer, which is analyzed using a fast coordinate. The problem is studied by applying a multiscale method. It is demonstrated that vibrations increase the critical value of the electric field strength for short-wave instability in the presence of an electric mode. In the case of the long-wave instability, vibrations increase the curvature of the neutral curve near the zero value of the wave number. As for the influence of the electric field on resonant modes, it can lead to the splitting of the first resonance into two or three modes, depending on the values of the Weber number. When splitting is absent, the electric field reduces the critical amplitude of the first resonant mode. Otherwise, the effect of the electric field is more complex. In the high-frequency limit, the expressions describing the critical value of the electric field strength are similar to those for the electric mode considered in the low-viscosity approximation for finite vibration frequencies, and no resonant perturbations occur in this case.

Image processing with a multi-level ultra-fast three dimensionally integrated perovskite nanowire array.

Besides its ubiquitous applications in optoelectronics, halide-perovskites (HPs) have also carved a niche in the domain of resistive switching memories (Re-RAMs). However owing to the material and electrical instability challenges faced by HP thin-films, rarely perovskite Re-RAMs are used to experimentally demonstrate data processing which is a fundamental requirement for neuromorphic applications. Here, for the first time, lead-free, ultrahigh density HP nanowire (NW) array Re-RAM has been utilized to demonstrate image processing via design of convolutional kernels. The devices exhibited superior switching characteristics including a high endurance of 5 × 106 cycles, an ultra-fast erasing and writing speed of 900 ps and 2 ns, respectively, and a retention time >5 × 104 s for the resistances. The work is bolstered by an in-depth mechanistic study and first-principles simulations which provide evidence of electrochemical metallization triggering the switching. Employing the robust multi-level switching behaviour, image processing functions of embossing, outlining and sharpening were successfully implemented.

Exome Sequencing Highlights a Potential Role for Concealed Cardiomyopathies in Youthful Sudden Cardiac Death.

Sudden cardiac arrest (SCA) and sudden unexplained death (SUD) are feared sequelae of many genetic heart diseases. In rare circumstances, pathogenic variants in cardiomyopathy-susceptibility genes may result in electrical instability leading to SCA/SUD before any structural manifestations of underlying cardiomyopathy are evident. Collectively, 38 unexplained SCA survivors (21 males; mean age at SCA 26.4±13.1 years), 68 autopsy-inconclusive SUD cases (46 males; mean age at death 20.4±9.0 years) without disease-causative variants in the channelopathy genes, and 973 ostensibly healthy controls were included. Following exome sequencing, ultrarare (minor allele frequency ≤0.00005 in any ethnic group within Genome Aggregation Database [gnomAD, N=141 456 individuals]) nonsynonymous variants identified in 24 Clinical Genome Resource adjudicated definitive/strong evidence cardiomyopathy-susceptibility genes were analyzed. Eligible variants were adjudicated as pathogenic, likely pathogenic, or variant of uncertain significance in accordance with current American College of Medical Genetics and Genomics guidelines. Overall, 7 out of 38 (18.4%) SCA survivors and 14 out of 68 (20.5%) autopsy-inconclusive, channelopathic-negative SUD cases had at least one pathogenic/likely pathogenic or a variant of uncertain significance nonsynonymous variant within a strong evidence, cardiomyopathy-susceptibility gene. Following American College of Medical Genetics and Genomics criterion variant adjudication, a pathogenic or likely pathogenic variant was identified in 3 out of 38 (7.9%; P=0.05) SCA survivors and 8 out of 68 (11.8%; P=0.0002) autopsy-inconclusive SUD cases compared to 20 out of 973 (2.1%) European controls. Interestingly, the yield of pathogenic/likely pathogenic variants was significantly greater in autopsy-inconclusive SUD cases with documented interstitial fibrosis (4/11, 36%) compared with only 4 out of 57 (7%, P<0.02) SUD cases without ventricular fibrosis. Our data further supports the inclusion of strong evidence cardiomyopathy-susceptibility genes on the genetic testing panels used to evaluate unexplained SCA survivors and autopsy-inconclusive/negative SUD decedents. However, to avoid diagnostic miscues, the careful interpretation of genetic test results in patients without overt phenotypes is vital.

RELATIONSHIP BETWEEN FRONTAL QRS-T ANGLE AND MYOCARDIAL PERFUSION DEFECT (MPD) FROM SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) IN PATIENTS WITH PRIOR MYOCARDIAL INFARCTION

Background: The frontal QRS-T angle is the angle between ventricular depolarization and repolarization. The QRS-T angle abnormalities will mirror the electrical instability, placing the patient in high risk of cardiac arrhythmia and sudden cardiac death. This study was conducted to analyzed as if the QRS-T angle will predict the myocardial perfusion defect in acute ST elevation myocardial infarction (STEMI).&#x0D; &#x0D; Methods: This is a cross sectional study which conducted in patients with previous history of STEMI in H. Adam Malik General Hospital Medan from June 2018 until March 2020. The patients will then be undergoing electrocardiography (ECG) and myocardial perfusion scintigraphy (SPECT) to acquire the frontal QRS-T angle and myocardial perfusion defect score.&#x0D; &#x0D; Results: Over 40 patients with prior STEMI we found the frontal QRS-T angle has a positive moderate correlation (r = 0,543; p &lt; 0,001) with myocardial perfusion defect. The best cut-off value for frontal QRS-T angle to predict myocardial perfusion defect is &gt; 70o with sensitivity and specificity of 70.6% and 82.6%, respectively.&#x0D; &#x0D; Conclusions: The frontal QRS-T angle is an independent predictor for myocardial perfusion defect in patient with previous history of STEMI.&#x0D; &#x0D; Keywords: STEMI; frontal QRS-T angle; myocardial perfusion defect.