Electrical Heterogeneity Research Articles

Quantitative analysis of tight sandstone reservoir heterogeneity based on rescaled range analysis and empirical mode decomposition: A case study of the Chang 7 reservoir in the Dingbian oilfield

Of the characteristics of tight sandstone reservoirs, heterogeneity is one of the most difficult characteristics to analyze. Heterogeneity is mainly manifested in three properties: lithology, porosity and electricity. The Chang 7 reservoir in the Dingbian oilfield is a tight sandstone reservoir controlled by delta front deposits. In this sedimentary environment, the underwater distributary channel oscillates frequently, resulting in considerable heterogeneity of the Chang 7 formation in the study area. The rescaled range method can calculate the fractal dimension D of logging curves, thus quantitatively characterizing reservoir heterogeneity. After analyzing the relationship between average wave number and IMF number by EMD method, the reservoir heterogeneity can be quantitatively characterized by ρ value. By comparing D value, ρ value and F value of different heterogeneous types, it is found that F value can distinguish different heterogeneous types. The order of F value also satisfies the actual situation of formation heterogeneity. The new heterogeneity coefficient is used to study the heterogeneity of Chang 7 reservoir, it is found that the relationship between the lithological heterogeneity represented by the natural gamma (GR) log and oil production is a quadratic function that initially increases and then decreases, that the relationship between the pore heterogeneity represented by the interval transit time (AC) log and oil production is linear, and that the relationship between the reservoir electrical heterogeneity represented by the deep induction log (LLD) and oil production is linear too.

A Protocol for Transverse Cardiac Slicing and Optical Mapping in Murine Heart.

Thin living tissue slices have recently emerged as a new tissue model for cardiac electrophysiological research. Slices can be produced from human cardiac tissue, in addition to small and large mammalian hearts, representing a powerful in vitro model system for preclinical and translational heart research. In the present protocol, we describe a detailed mouse heart transverse slicing and optical imaging methodology. The use of this technology for high-throughput optical imaging allows study of electrophysiology of murine hearts in an organotypic pseudo two-dimensional model. The slices are cut at right angles to the long axis of the heart, permitting robust interrogation of transmembrane potential (Vm) and calcium transients (CaT) throughout the entire heart with exceptional regional precision. This approach enables the use of a series of slices prepared from the ventricles to measure Vm and CaT with high temporal and spatial resolution, allowing (i) comparison of successive slices which form a stack representing the original geometry of the heart; (ii) profiling of transmural and regional gradients in Vm and CaT in the ventricle; (iii) characterization of transmural and regional profiles of action potential and CaT alternans under stress (e.g., high frequency pacing or β-adrenergic stimulation) or pathological conditions (e.g., hypertrophy). Thus, the protocol described here provides a powerful platform for innovative research on electrical and calcium handling heterogeneity within the heart. It can be also combined with optogenetic technology to carry out optical stimulation; aiding studies of cellular Vm and CaT in a cell type specific manner.

The possibility to obtain ZnSe crystals with high structural perfection for cryogenic bolometric technics

In this work the samples of ZnSe zinc selenide crystal grown from the melt by Bridgman method from high-purity (chemical and radio) raw materials were studied for further use in experiments on the search for neutrinoless double beta decay. The microstructure of the test samples was studied. Chemical selective etching, first of all, has allowed to determine the nature of distribution and sizes of area twinning, as well as the etch pits along twins boundaries. It is shown the figures found by chemical etching are the dislocation exits to the studied crystal surface. The dislocation density was estimated by counting the dislocation etch pits on the plane perpendicular to the growth direction and was 104 cm-2. As a rule, thermophysical conditions of ZnSe crystal growth, as well as high concentration of foreign inclusions and impurities in the crystal significantly affect the formation of twins and growth dislocations and are the cause of the optical, electrical, and mechanical heterogeneity of the material. The optical and electrical characteristics of the samples were measured. The absorption bands observed in the optical transmission spectra of the visible and IR ranges gave important information about the presence of local defects and impurities in the crystal, namely in 470÷550 nm and 580÷650 nm regions – absorption by point defects and in 3÷15 μm region – Fe2+, CSe and CSe2 absorption. The total transmission level in the visible range reached 60 %, which is lower than the theoretical one and due to scattering by defects. The phonon thermal conductivity of ZnSe sample was measured in the temperature range 5÷298 K. Based on the approximation of obtained temperature dependences of the thermal conductivity, it was shown that the phonon mean free path at low temperatures is comparable with the distance between twins’ boundaries in the sample.

A Multi-Scale Investigation of Global Electrical Heterogeneity: Effects of Body Habitus, Respiration, and Tissue Conductivity.

Extracardiac factors such as respiration, fluid overload and body habitus have important effects on the ECG voltage. Vectorcardiographic (VCG) Global Electrical Heterogeneity (GEH) is associated with sudden cardiac death (SCD). Risk of SCD is especially high in end-stage renal disease patients (ESRD) on dialysis. However, extracardiac factors challenge ECG interpretation in ESRD patients. The effects of extracardiac factors on GEH have not been fully studied. To1 assess effects of extracardiac factors on ECG, we conducted a multi-scale study. An experimental data of ESRD patients and a previously developed biophysically detailed heart-torso model were used to investigate the effects of respiration, fluid overload and body habitus on the VCG and GEH.

The Reproducibility of Global Electrical Heterogeneity ECG Measurements.

Global electrical heterogeneity (GEH) is a useful predictor of adverse clinical outcomes. However, reproducibility of GEH measurements on 10-second routine clinical ECG is unknown. Data of the prospective cohort study of incident hemodialysis patients (n=253; mean age 54.6±13.5y; 56% male; 79% African American) were analysed. Two random 10-second segments of 5-minute ECG recording in sinus rhythm were compared. GEH was measured as spatial QRS-T angle, spatial ventricular gradient (SVG) magnitude and direction (azimuth and elevation), and a scalar value of SVG measured by (1) sum absolute QRST integral (SAI QRST), and (2) QT integral on vector magnitude signal (iVMQT). Bland-Altman analysis was used to calculate agreement. For all studied vectorcardiographic metrics, agreement was substantial (Lin's concordance coefficient >0.98), and precision was perfect (>99.99%). 95% limits of agreement were ±14° for spatial QRS-T angle, ±13° for SVG azimuth, ±4° for SVG elevation, ±14 mV*ms for SVG magnitude, and ±17 mV*ms for SAI QRST. SAI QRST and iVMQT were in substantial agreement with each other. Reproducibility of a 10-second automated GEH ECG measurements was substantial, and precision was perfect.

Global Electrical Heterogeneity: Mechanisms and Clinical Significance.

This review summarizes recent findings and discusses a clinical significance of a vectorcardiographic (VCG) Global electrical heterogeneity (GEH). GEH concept is based on the concept of the spatial ventricular gradient (SVG), which is a global measure of the dispersion of total recovery time. We quantify GEH by measuring five features of the SVG vector (SVG magnitude, direction (azimuth and elevation), a scalar value, and spatial QRS-T angle) on orthogonal XYZ ECG. In analysis of more than 20,000 adults we showed that GEH is independently associated with sudden cardiac death (SCD) after adjustment for demographics, cardiovascular disease (time-updated incident non-fatal cardiovascular events [coronary heart disease, heart failure, stroke, atrial fibrillation, use of beta-blockers], and known risk factors [cholesterol, triglycerides, physical activity index, smoking, diabetes, obesity, hypertension, anti-hypertensive medications, creatinine, alcohol intake, left ventricular ejection fraction, and time-updated ECG metrics (heart rate, QTc, QRS duration, ECG-left ventricular hypertrophy, bundle branch block or interventricular conduction delay)]. This finding suggests that GEH represents an independent electrophysiological substrate of SCD.

Спектральные свойства флуктуаций концентрационного поля в электромембранных системах с сульфокатионообменными мембранами с разной дисперсностью ионообменника

Методом Фурье-анализа определен спектральный состав флуктуаций концентрационного поля в стратифицированных системах с экспериментальными гетерогенными сульфокатионообменными мембранами Ralex CM Pes («MEGA» a.s., Чехия), содержащими ионообменник различной дисперсности. С увеличением времени измельчения ионообменных частиц, соответственно степени их дисперсности, выявлено уменьшение размеров проводящих участков и расстояния между ними на поверхности мембран. Высокая шумовая составляющая колебаний концентрационного поля в растворе вследствие развития электроконвективных вихрей установлена на границе с мембраной, характеризующейся более однородной поверхностью.

Effect of Dispersity of a Sulfonated Cation-Exchanger on the Current–Voltage Characteristics of Heterogeneous Membranes Ralex CM Pes

The influence of the electrical and geometrical heterogeneity of the surface of heterogeneous sulfonated cation-exchange membranes on their current–voltage characteristic (CVC) has been experimentally studied. The objects of the study have been experimental samples of Ralex CM Pes membranes manufactured by MEGA a.s. (Czech Republic). A series of experimental membranes Ralex has been produced by hot rolling using an ion-exchanger with different particle sizes. The particle size of the ion-exchanger was controlled by its milling time from 5 to 80 min. It has been found that in the swollen state of the membranes, the ratio of conducting (ion-exchanger particles) and inert (polyethylene) areas on the membrane surface remains constant regardless of the milling time of the sulfonated cation-exchanger. At the same time, the dimensions of the conductive areas and the distance between them decreased and the surface microrelief became smoother. The influence of changes in the membrane surface properties on the CVC parameters has been revealed. With an increase in the ion-exchanger milling time corresponding to a decrease in the spacing of electrical heterogeneity of the surface, a reduction in the length of limiting-current plateau and a decrease in the resistance of the second and third regions on the current–voltage curve were observed. It has been assumed that the main cause of changes in the current–voltage characteristics is an increase in the intensity of heteroelectroconvection.

Importance of the heart vector origin point definition for an ECG analysis: The Atherosclerosis Risk in Communities (ARIC) study

AimOur goal was to investigate the effect of a global XYZ median beat construction and the heart vector origin point definition on predictive accuracy of ECG biomarkers of sudden cardiac death (SCD). MethodsAtherosclerosis Risk In Community study participants with analyzable digital ECGs were included (n = 15,768; 55% female, 73% white, mean age 54.2 ± 5.8 y). We developed an algorithm to automatically detect the heart vector origin point on a median beat. Three different approaches to construct a global XYZ beat and two methods to locate origin point were compared. Global electrical heterogeneity was measured by sum absolute QRST integral (SAI QRST), spatial QRS-T angle, and spatial ventricular gradient (SVG) magnitude, azimuth, and elevation. Adjudicated SCD served as the primary outcome. ResultsThere was high intra-observer (kappa 0.972) and inter-observer (kappa 0.984) agreement in a heart vector origin definition between an automated algorithm and a human. QRS was wider in a median beat that was constructed using R-peak alignment than in time-coherent beat (88.1 ± 16.7 vs. 83.7 ± 15.9 ms; P < 0.0001), and on a median beat constructed using QRS-onset as a zeroed baseline, vs. isoelectric origin point (86.7 ± 15.9 vs. 83.7 ± 15.9 ms; P < 0.0001). ROC AUC was significantly larger for QRS, QT, peak QRS-T angle, SVG elevation, and SAI QRST if measured on a time-coherent median beat, and for SAI QRST and SVG magnitude if measured on a median beat using isoelectric origin point. ConclusionTime-coherent global XYZ median beat with physiologically meaningful definition of the heart vector's origin point improved predictive accuracy of SCD biomarkers.

Vectorcardiogram in athletes: The Sun Valley Ski Study.

Global electrical heterogeneity (GEH) is associated with sudden cardiac death (SCD) in adults of 45years and above. However, GEH has not been previously measured in young athletes. The goal of this study was to establish a reference for vectorcardiograpic (VCG) metrics in male and female athletes. Skiers (n=140; mean age 19.2±3.5years; 66% male, 94% white; 53% professional athletes) were enrolled in a prospective cohort. Resting 12-lead ECGs were interpreted per the International ECG criteria. Associations of age, sex, and athletic performance with GEH were studied. In age and training level-adjusted analyses, male sex was associated with a larger T vector [T peak magnitude +186 (95% CI 106-266) µV] and a wider spatial QRS-T angle [+28.2 (17.3-39.2)°] as compared to women. Spatial QRS-T angle in the ECG left ventricular hypertrophy (LVH) voltage group (n=21; 15%) and normal ECG group did not differ (67.7±25.0 vs. 66.8±28.2; p=0.914), suggesting that ECG LVH voltage in athletes reflects physiological remodeling. In contrast, skiers with right ventricular hypertrophy (RVH) voltage (n=26, 18.6%) had wider QRS-T angle (92.7±29.6 vs. 66.8±28.2°; p=0.001), larger SAI QRST (194.9±30.2 vs. 157.8±42.6mV×ms; p<0.0001), but similar peak SVG vector magnitude (1976±548 vs. 1939±395µV; p=0.775) as compared to the normal ECG group. Better athletic performance was associated with the narrower QRS-T angle. Each 10% worsening in an athlete's Federation Internationale de' Ski downhill ranking percentile was associated with an increase in spatial QRS-T angle by 2.1 (95% CI 0.3-3.9) degrees (p=0.013). Vectorcardiograpic adds nuances to ECG phenomena in athletes.

The spatial inhomogeneity and X-ray absorption spectroscopy of superconducting nanocrystalline boron doped diamond films

The local electrical conductivity and impurity band evolution in superconducting nanocrystalline boron doped diamond (BNCD) film are investigated using conducting atomic force microscopy (C-AFM) and X-ray absorption spectroscopy (XAS). C-AFM has been employed to investigate the local conductivity of superconducting BNCD with Tc = 4.3 K and upper critical field Hc2(0) = 5.2 T. A high local electrical heterogeneity of the BNCD film as evidenced from the C-AFM profile points to the uneven boron uptake during the process of doping. C-AFM also revealed that grain boundaries are the highly conducting regions, possibly, due to the presence of p-type trans-polyacetylene along with the CC and CH bonds in the grain boundaries. From the in-depth XPS profiling of the B 1s spectra we confirmed the macroscopic uniformity of the boron concentration across the depth of BNCD layers. X-ray absorption spectroscopy (XAS) measurements near B K-edge and C K-edge showed formation of in-gap states as a result of heavy boron doping. Near C K-edge, bandgap states at 282.8 eV and 284.1 eV are found which are responsible for superconductivity in the BNCD film. This work explores the non-uniform boron doping and its effect on the conduction band structure of a superconducting BNCD film.

Mapping electrical properties heterogeneity of tumor using boundary informed electrical properties tomography (BIEPT) at 7T.

To develop and evaluate a boundary informed electrical properties tomography (BIEPT) technique for high-resolution imaging of tumor electrical properties (EPs) heterogeneity on a rodent tumor xenograft model. Tumor EP distributions were inferred from a reference area external to the tumor, as well as internal EP spatial variations derived from a plurality of relative transmit B1 measurements at 7T. Edge sparsity constraint was enforced to enhance numerical stability. Phantom experiments were performed to determine the imaging accuracy and sensitivity for structures of various EP values, as well as geometrical sizes down to 1.5 mm. Numerical simulation of a realistic rodent model was used to quantify the algorithm performance in the presence of noise. Eleven athymic rats with human breast cancer xenograft were imaged in vivo, and representative pathological samples were acquired for comparison. Reconstructed EPs of the phantoms correspond well to the ground truth acquired from dielectric probe measurements, with the smallest structure reliably detectable being 3 mm. EPs heterogeneity inside a tumor is successfully retrieved in both simulated and experimental cases. In vivo tumor imaging results demonstrate similar local features and spatial patterns to anatomical MRI and pathological slides. The imaged conductivity of necrotic tissue is higher than that of viable tissues, which agrees with our expectation. BIEPT enables robust detection of tumor EPs heterogeneity with high accuracy and sensitivity to small structures. The retrieved quantitative EPs reflect tumor pathological features (e.g., necrosis). These results provide strong rationale to further expand BIEPT studies toward pathological conditions where EPs may yield valuable, non-invasive biomarkers.

Effect of the sulfocation-exchanger dispersity on the surface morphology, microrelief of heterogeneous membranes and development of electroconvection in intense current modes

Comparative analysis of the effect of electrical and geometric heterogeneity of the surface of heterogeneous sulfocation-exchanger membranes Ralex CM Pes produced by MEGA a.s. (Czech Republic) and the Russian membranes MK-40 manufactured by JSC “Shchekinoazot” on current voltage characteristics (CVC), conditions of occurrence and intensity of electroconvective instability at the membrane/solution interface in intense current modes was carried out. Membranes MK-40 were prepared by hot-pressing technology (https://www.n-azot.ru), membranes Ralex CM Pes by hot-rolling technology (https://www.mega.cz). In the manufacture of the membranes Ralex CM Pes, the milling time for sulfocation-exchanger on a ball mill varied from 5 to 80 min, the volume ratio of cation-exchanger to polyethylene was kept the same. It was found that in the swollen state of the membranes with the increase in the milling time of the ion-exchanger, the ratio between the conducting (ion-exchanger grain) and inert (polyethylene) sections on the surface of the membranes remained constant, and the size of the conducting sections and the distances between them decreased, while the surface microrelief became smoother. Despite the decrease in roughness of the membrane surface, as the degree of dispersity of the initial sulfocation-exchanger increases, the CVC of the membranes show an increase in the limiting diffusion current, a reduction of the plateau section of the limiting current, and an increase in the size of the electroconvective instability region in the solution at the interphase boundary. These facts indicate that when the conditions of the membrane-preparing technology change, a more significant factor determining the conditions for the occurrence and intensity of the development of heteroelectroconvection is a decrease in the electrical heterogeneity of the membrane surface.

Global electrical heterogeneity as a predictor of cardiovascular mortality in men and women.

The aim of this study was to investigate the contribution of depolarization and repolarization abnormalities, specially abnormalities in global electrical heterogeneity of heart in cardiovascular disease (CVD) and all-cause mortality. Eight hundred and forty men and 911 women, average age of 63 years participated in this study with average follow-up was 14 years. Six electrocardiogram/vector electrocardiogram (ECG/VECG) markers QRS-duration, QTc-interval, QRST-angle, sum of absolute QRST integral (SAI QRST), T-wave roundness, and TV1-amplitude were estimated from VECG measurements. Hazard ratios (HRs) for CVD events (164 deaths) and all-cause mortality (383 deaths) for ECG parameters were calculated. Electrocardiogram or vector electrocardiogram parameter models adjusted for risk clinical factors showed that strongest predictors for CVD mortality were QRST-angle (HR 3.44, 95% confidence interval 2.12-5.36), QTc-interval (2.72, 1.73-4.29), and T-wave roundness (2.09, 1.26-3.46) among men. The strongest ECG/VECG parameters for CVD death were QRST-angle (2.47, 1.37-4.45), SAI QRST (2.37, 1.23-4.6), and QTc-interval (2.15, 1.16-4.01) among female participants. Multivariable adjusted models revealed that strongest independent ECG predictors for CVD death were QRST-angle, QTc-interval, resting heart rate, and T-roundness for men, QRST-angle and SAI QRST for women. QRST-angle, QTc-interval, resting heart rate, and T-roundness were associated with all-cause mortality in male population, although none of the ECG/VECG parameters predicted all-cause mortality among women. Characteristics of global electrical heterogeneity QRST-angle and QTc-interval in men and QRST-angle and SAI QRST among females were strong and independent risk markers for cardiovascular mortality. These parameters provide new additional ECG tools for cardiovascular risk stratification.

Impact of heterogeneous cation-exchange membrane surface modification on chronopotentiometric and current–voltage characteristics in NaCl, CaCl2 and MgCl2 solutions

Chronopotentiograms and current-voltage curves were measured to characterize the transport of sodium, calcium, and magnesium ions through cation-exchange membranes MK-40 and MK-40MOD. A microfluidic electrodialysis cell was used to visualize electroconvective vortices. The MK-40MOD membrane was obtained by covering the heterogeneous surface of a commercial MK-40 membrane with a thin (about 15 μm) homogeneous film of the MF-4SK sulfonated fluoropolymer. It has been shown that the combination of relatively high hydrophobicity of the MK-40MOD membrane surface with a certain electrical and geometrical (surface undulation) heterogeneity facilitate the generation of electroconvective vortices. The effect of vortices is manifested in reduction of the potential drop under a fixed current density and potential oscillations on the chronopotentiogram. It was found that in all studied systems potential drop in stationary state decreases in the order Na+>Ca2+>Mg2+. This correlates with the amplitude of potential drop oscillations (which increases in the range Na+<Ca2+<Mg2+) and with the size of electroconvection vortices observed in the microfluidic cell: its size is higher in the case of MgCl2 compared to the CaCl2 solution. Oscillations of potential drop on chronopotentiogram were registered not only in stationary state, but also at times of the order of several seconds, lower than the transition time. These oscillations occurred in the case of MgCl2 for both membranes, in the case of CaCl2 for the MK-40MOD membrane. No earlier oscillations were observed in the case of NaCl. The appearance of earlier potential drop oscillations is accompanied by an increase in the transition time and a reduction in the potential drop. The earlier oscillations are explained by the onset of unstable equilibrium electroconvection recently described by Rubinstein and Zaltzman. Stronger electroconvection in the case of MgCl2 in comparison to CaCl2 and NaCl is attributed to the impact of the residual space charge of bulk solution, which is the highest for the MgCl2 among the studied electrolytes. The contribution of bulk electroconvection is discussed on the basis of the estimation of the thicknesses of the diffusion layer and its constituting zones as functions of the current density.

Characterization of bulk and surface properties of anion-exchange membranes in initial stages of fouling by red wine

Electrodialysis finds broader use in reagent-free pH correction and tartrate stabilization of wines. The efficiency of these processes strongly depends on longevity of employed anion-exchange membranes. We report a comprehensive study of bulk and surface properties of a homogeneous Neosepta AMX-Sb and a heterogeneous MA-41P anion-exchange membranes after its contact with a red wine for 3, 10 and 72 h. The ion-exchange capacity, conductivity, thickness, as well as surface roughness (AFM and optical microscopy), local surface and bulk pH (by color indicator), surface chemical structure (ATR FTIR), contact angle and surface charge are measured. In addition, the AMX-Sb membrane is characterized by voltammetry and pH-metry. It is found that polyphenols act an important role in membrane fouling. Initially, it is relatively small and mobile anthocyanins, which penetrate inside the membrane; then they are followed by larger and slower tannins and/or anthocyanin-tannin complexes. Polyphenols together with polysaccharides and other wine constituents form colloidal aggregates, which fill the membrane pores and are deposited by islets on the surface as a foulant layer. The appearance of this layer increases hydrophilicity of the surface while reducing its charge. The membrane conductivity decreases with increasing the duration of membrane contact with wine. However, the effect of this contact on the limiting current density, ilim, overlimiting transfer and water splitting is unexpected. In early stages of fouling, ilim of the AMX-Sb membrane increases and water splitting is found suppressed, electroconvection is essentially enhanced. The latter should be due to the isle-type structure of the foulant layer: surface electrical heterogeneity promotes electroconvection. However, the contact of the membrane with wine for several tens of hours results in formation of all-over foulant layer stimulating water splitting and reducing electroconvection.

Phenomenon of two transition times in chronopotentiometry of electrically inhomogeneous ion exchange membranes

Transition time in chronopotentiometry is an important parameter, which is widely used for electrochemical characterization of various systems. Occurrence of multiple transition times is typical for multicomponent or multilayer electrode and membrane systems. In this paper we show that there may be another cause of multiple transition times. It is electrical heterogeneity of ion exchange membrane surface. It is found that there are two transition times on the chronopotentiograms of a commercial anion-exchange MA-41 (Shchekinoazot) and two specially prepared cation-exchange heterogeneous membranes in dilute electrolyte solutions (0.02 M NaCl in the experiment). It is found that both transition times are determined by diffusion limitations of ion delivery to the membrane surface in the depleted diffusion layer. The value of the first transition time depends on the dimensions of the conductive regions and their surface fraction; this transition time is determined as the time necessary for the depletion of electrolyte concentration near the conductive regions of the surface. The rate of concentration depletion depends on the electromigration through the conductive regions, on the one hand, and on the normal the tangential ion diffusion to the conductive surface regions, which mitigate the concentration decrease, on the other hand. The experimental value of the first transition time for the laboratory-made membranes is in a good agreement with simulation using a 3D electrodiffusion model. The value of the second transition time is in a good agreement with the Sand theory, hence it is conditioned by the normal diffusion delivery of electrolyte from the solution bulk to the entire membrane surface. The tangential diffusion plays a secondary role in this stage of concentration polarization since current-induced convection levels off the concentrations along the heterogeneous membrane surface.

Genome-Wide Associations of Global Electrical Heterogeneity ECG Phenotype: The ARIC (Atherosclerosis Risk in Communities) Study and CHS (Cardiovascular Health Study).

Background ECG global electrical heterogeneity (GEH) is associated with sudden cardiac death. We hypothesized that a genome‐wide association study would identify genetic loci related to GEH.Methods and ResultsWe tested genotyped and imputed variants in black (N=3057) and white (N=10 769) participants in the ARIC (Atherosclerosis Risk in Communities) study and CHS (Cardiovascular Health Study). GEH (QRS‐T angle, sum absolute QRST integral, spatial ventricular gradient magnitude, elevation, azimuth) was measured on 12‐lead ECGs. Linear regression models were constructed with each GEH variable as an outcome, adjusted for age, sex, height, body mass index, study site, and principal components to account for ancestry. GWAS identified 10 loci that showed genome‐wide significant association with GEH in whites or joint ancestry. The strongest signal (rs7301677, near TBX3) was associated with QRS‐T angle (white standardized β+0.16 [95% CI 0.13–0.19]; P=1.5×10−26), spatial ventricular gradient elevation (+0.11 [0.08–0.14]; P=2.1×10−12), and spatial ventricular gradient magnitude (−0.12 [95% CI −0.15 to −0.09]; P=5.9×10−15). Altogether, GEH‐SNPs explained 1.1% to 1.6% of GEH variance. Loci on chromosomes 4 (near HMCN2), 5 (IGF1R), 11 (11p11.2 region cluster), and 7 (near ACTB) are novel ECG phenotype‐associated loci. Several loci significantly associated with gene expression in the left ventricle (HMCN2 locus—with HMCN2;IGF1R locus—with IGF1R), and atria (RP11‐481J2.2 locus—with expression of a long non‐coding RNA and NDRG4).ConclusionsWe identified 10 genetic loci associated with ECG GEH. Replication of GEH GWAS findings in independent cohorts is warranted. Further studies of GEH‐loci may uncover mechanisms of arrhythmogenic remodeling in response to cardiovascular risk factors.

Improving sudden cardiac death risk stratification by evaluating electrocardiographic measures of global electrical heterogeneity and clinical outcomes among patients with implantable cardioverter-defibrillators: rationale and design for a retrospective, multicenter, cohort study.

Implantable cardioverter-defibrillators (ICDs) improve survival of systolic heart failure (HF) patients who are at risk of sudden cardiac death (SCD). We recently showed that electrocardiographic (ECG) global electrical heterogeneity (GEH) is independently associated with SCD in the community-dwelling cohort and developed GEH SCD risk score. The Global Electrical Heterogeneity and Clinical Outcomes (GEHCO) study is a retrospective multicenter cohort designed with two goals: (1) validate an independent association of ECG GEH with sustained ventricular tachyarrhythmias and appropriate ICD therapies and (2) validate GEH ECG risk score for prediction of sustained ventricular tachyarrhythmias and appropriate ICD therapies in systolic HF patients with primary prevention ICD. All records of primary prevention ICD recipients with available data for analysis are eligible for inclusion. Records of ICD implantation in patients with inherited channelopathies and cardiomyopathies are excluded. Raw digital 12-lead pre-implant ECGs will be used to measure GEH (spatial QRST angle, spatial ventricular gradient magnitude, azimuth, and elevation, and sum absolute QRST integral). The primary endpoint is defined as a sustained ventricular tachyarrhythmia event with appropriate ICD therapy. All-cause death without preceding sustained ventricular tachyarrhythmia with appropriate ICD therapy will serve as a primary competing outcome. The study will draw data from the academic medical centers. We describe the study protocol of the first multicenter retrospective cohort of primary prevention ICD patients with recorded at baseline digital 12-lead ECG. Findings from this study will inform future trials to identify patients who are most likely to benefit from primary prevention ICD. URL: http://www.clinicaltrials.gov . Unique identifier: NCT03210883.

ASSOCIATION BETWEEN SPATIAL VENTRICULAR GRADIENT DIRECTION AND REGIONAL MYOCARDIAL DEFORMATION IN THE GENERAL POPULATION: THE ATHEROSCLEROSIS RISK IN COMMUNITIES (ARIC) STUDY

Measures of global electrical heterogeneity (GEH), such as spatial ventricular gradient (SVG) reflect cardiac electrophysiological substrate associated with sudden cardiac death. We hypothesized that SVG direction on ECG is associated with regional myocardial deformation, and that this association