Prolonged Activation Time Research Articles

Prolonged ventricular activation time as a novel biomarker identifying burn-out phase of hypertrophic cardiomyopathy

Abstract Background Patients with hypertrophic cardiomyopathy (HCM) classically have preserved systolic function and decreased left ventricular end-diastolic volume. However, in a small sub-population, patients paradoxically develop systolic dysfunction, left ventricular dilatation, and ventricular wall thinning, which is known as end-stage hypertrophic cardiomyopathy or "burned-out cardiomyopathy’. Although an electrocardiogram (ECG) is a pivotal tool in HCM, its role in the detection of burned-out HCM has not been investigated. Purpose We assessed the ventricular activation time (VAT), an ECG marker of the duration of ventricular depolarization, as a predictive tool in the detection of the HCM burn-out phase. Methods We prospectively studied consecutive patients diagnosed with HCM via echocardiography at our medical center between 2017 and 2022. The ECG, along with echocardiography, was performed on the same day as the diagnosis. VAT was measured in milliseconds between the onset of the QRS complex to the peak or R wave on the V5 and V6 precordial ECG lead. HCM burn-out phase was supported when the left ventricular ejection fraction (LVEF) was below 50%, measured with echocardiography. Statistical analysis was performed using the SPSS software. Results Forty-five patients with HCM were studied, and their mean age was 51, while 78% (35/45) were male. Echocardiography data upon diagnosis revealed a mean maximum wall thickness of 19 (±3mm) and a mean left ventricular ejection fraction of 65% (±5%). Left ventricular outflow obstruction was present in 31% (14/45). During the study, 24% (11/45) presented atrial fibrillation, 44% (20/45) had an ICD implantation, and 22% (10/45) progressed to the burn-out phase of HCM. HCM patients who presented atrial fibrillation (63±31 vs. 46±14msec, p=0.018) or burn-out phase (65±32 vs. 46±13msec, p=0,009) had a significantly higher VAT than those subsets without. Notably, there was a significant positive relationship between VAT a burn-out phenotype (r=0,385, p=0.009). HCM patients with greater VAT also had a significantly higher risk of presenting a larger left atrial diameter (r=0,295, p=0.048), an increased left ventricular end-diastolic diameter (r=0.306, p=0.041), and a trend of presenting a lower LVEF (r=-0,262, p=0.082). Finally, we revealed a positive relationship between VAT and atrial fibrillation incidence (r=0,352, p=0.018). Conclusion Prolongation of VAT predicts the incidence of burn-out stage in patients with HCM and atrial fibrillation. Therefore, it seems to be a promising, inexpensive ECG marker for HCM progression and severity. Our findings emphasize the pivotal role of the ECG as a useful and inexpensive tool in the diagnostic follow-up of HCM.

Evaluation of Cold Plasma–Activated water “…Enriched Metal…” Cations as an Antifungal Agent for Controlling of Penicillium italicum and Penicillium digitatum Molds

The utilization of Cold Plasma (CP) technology for decontamination and disinfection has garnered considerable attention across diverse industries. This study aims to investigate the interaction between pH and electrical conductivity (EC) (μS/cm) in Cold Plasma-Activated Water (CPAW) enriched with metal cations and its potential as an antifungal agent against two Penicillium (P.) mold strains. The investigation focuses on elucidating the augmented chemical interactions induced by plasma between radicals, charged particles, and microorganisms' cell membranes within an aqueous environment. Our findings demonstrate a positive correlation between the inactivation potential of CPAW (operating at 10 kV voltage, 2.5 kHz high frequency, and 500 mA current intensity) and pH and EC(μS/cm) values. Notably, the relative chemical reactivity and solubility of calcium oxide emerge as significant factors, highlighting the pronounced link between P. Italicum and Plasma-Activated Water containing Copper cations (CPAW + Cu2+) (p < 0.05). Our study distinctly emphasizes (1) the substantial impact of both activated water type and mold species on CFU/mL values (p < 0.05); (2) the mold-specific effect of activated water on CFU/mL; and (3) the noteworthy EC(μS/cm) enhancement and pH decrease with prolonged activation time, attaining statistical significance (p < 0.01).

Transfiguration of Human Atrioventricular Conduction Axis with His bundle Pacing: Effect on Underlying Bundle Branch Block

His bundle pacing comes with the expectation of avoiding morbidity and mortality associated with pacing the ventricular myocardium. The paced complex typically exhibits a delta wave and resembles the relatively normal QRS complex of fasciculoventricular preexcitation. In patients with atrioventricular conduction disease, His bundle pacing ‘corrects’ both right and left bundle branch block. Conduction block is known to have a diffuse substrate and mechanism of correction remains unclear. In 51 patients with normal QRS complex, 35 patients with right bundle branch block and left axis deviation, and 41 patients with left bundle branch block we analyzed the changes in the paced QRS complex. In all patients His bundle pacing caused a decrease in ventricular activation time, an increase in lead 1 voltage, an inferior shift in the frontal QRS axis, and a rightward shift in R wave transition in the precordial leads. In patients with normal QRS, despite these changes, the paced QRS remained in normal range. In left bundle branch block, these changes resulted in decrease of prolonged ventricular activation time, increased lead 1 voltage , and normalized the delayed R wave transition in precordial leads. The correction of right bundle branch block suggested that the right ventricular free wall was being activated earlier. This was consistent with early rightward transition of precordial R waves and the inferior QRS axis and the known base to apex activation of right ventricular wall in fasciculoventricular preexcitation. We conclude that the QRS complex in normal range, seen in fasciculoventricular preexcitation, is caused by rapidly conducting, base-to-apex, and septum to lateral wall activation in both left and right ventricles. This would explain the correction of left axis deviation and reversal of delayed lateral wall activation in right and left bundle branch block, by His bundle pacing.

AF Inducibility Is Related to Conduction Abnormalities at Bachmann's Bundle.

We investigated whether patterns of activation at Bachmann’s bundle are related to AF inducibility. Epicardial mapping of Bachmann’s bundle during sinus rhythm was performed prior to cardiac surgery (192 electrodes, interelectrode distances: 2 mm). Compared to non-inducible patients (N = 20), patients with inducible AF (N = 34) had longer lines of conduction block (18(2–164) mm vs. 6(2–28) mm, p = 0.048), prolonged total activation time (55(28–143) ms vs. 46(24–73) ms, p = 0.012), multiple wavefronts entering Bachmann’s bundle more frequently (64% vs. 37%, p = 0.046) and more often areas of simultaneous activation (conduction velocity > 1.7 m/s, 45% vs. 16%, p = 0.038). These observations further support a relation between conduction abnormalities at Bachmann’s bundle and AF inducibility. The next step is to examine whether Bachmann’s bundle activation patterns can also be used to identify patients who will develop AF after cardiac surgery during both short- and long-term follow-up.

Non-selective and selective His bundle pacing both preserve left ventricular activation time and pattern

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Background: His bundle pacing can be achieved in two ways selective His bundle pacing, where the His bundle is captured alone, and non-selective His bundle pacing, where local myocardium is also captured resulting a pre-excited ECG appearance. We assessed the impact of this ventricular pre-excitation on left and right ventricular dys-synchrony. Methods We recruited patients who displayed both selective and non-selective His bundle pacing. We performed non-invasive epicardial electrical mapping to determine left and right ventricular activation times and patterns. Results In the primary analysis (n = 20, all patients), non-selective His bundle pacing did not prolong LVAT compared to select His bundle pacing by a pre-specified non-inferiority margin of 10ms (LVAT prolongation: -5.5ms, 95% confidence interval (CI): -0.6 to -10.4, non-inferiority p &amp;lt; 0.0001). Non-selective His bundle pacing did not prolong right ventricular activation time (4.3ms, 95%CI: -4.0 to 12.8, p = 0.296) but did prolong QRS duration (22.1ms, 95%CI: 11.8 to 32.4, p = 0.0003). In patients with narrow intrinsic QRS (n = 6), non-selective His bundle pacing preserved left ventricular activation time (-2.9ms, 95%CI: -9.7 to 4.0, p = 0.331) but prolonged QRS duration (31.4ms, 95%CI: 22.0 to 40.7, p = 0.0003) and mean right ventricular activation time (16.8ms, 95%CI: -5.3 to 38.9, p = 0.108) compared to selective His bundle pacing. Activation pattern of the left ventricular surface was unchanged between selective and non-selective His bundle pacing. Non-selective His bundle pacing produced early basal right ventricular activation, which was not observed with selective His bundle pacing. Conclusions Compared to selective His bundle pacing, local myocardial capture during non-selective His bundle pacing produces right ventricular pre-excitation resulting in prolongation of QRS duration. However, non-selective His bundle pacing preserves the left ventricular activation time and pattern of selective His bundle pacing. When choosing between selective and non-selective His bundle pacing, left ventricular dyssynchrony is not an important factor. Abstract Figure: Selective vs Non-Selective HBP

Right Ventricular Longitudinal Conduction Delay in Patients with Brugada Syndrome.

BackgroundThe mechanism of Brugada syndrome (BrS) is still unclear, with different researchers favoring either the repolarization or depolarization hypothesis. Prolonged longitudinal activation time has been verified in only a small number of human right ventricles (RVs). The purpose of the present study was to demonstrate RV conduction delays in BrS.MethodsThe RV outflow tract (RVOT)-to-RV apex (RVA) and RVA-to-RVOT conduction times were measured by endocardial stimulation and mapping in 7 patients with BrS and 14 controls.ResultsPatients with BrS had a longer PR interval (180 ± 12.6 vs. 142 ± 6.7 ms, P = 0.016). The RVA-to-RVOT conduction time was longer in the patients with BrS than in controls (stimulation at 600 ms, 107 ± 9.9 vs. 73 ± 3.4 ms, P = 0.001; stimulation at 500 ms, 104 ± 12.3 vs. 74 ± 4.2 ms, P = 0.037; stimulation at 400 ms, 107 ±12.2 vs. 73 ± 5.1 ms, P = 0.014). The RVOT-to-RVA conduction time was longer in the patients with BrS than in controls (stimulation at 500 ms, 95 ± 10.3 vs. 62 ± 4.1 ms, P = 0.007; stimulation at 400 ms, 94 ±11.2 vs. 64 ± 4.6 ms, P = 0.027). The difference in longitudinal conduction time was not significant when isoproterenol was administered.ConclusionThe patients with BrS showed an RV longitudinal conduction delay obviously. These findings suggest that RV conduction delay might contribute to generate the BrS phenotype.

Fabrication and Characterization of Activated Carbon Fibers from Oil Palm Trunk.

To develop more valuable application, oil palm trunk was successfully converted into activated carbon fibers (ACFs). An effective process of chemical treatment with dilute sulfuric acid was conducted to improve the thermal stability of primary fibers for further heating treatment. Carbon dioxide (CO2) was used as activator to produce much porous structure with various pore diameter. The specific surface area (SBET) and total pore volume (Vtotal) of resultant ACFs showed increasing trend as rise of activation temperature and time. The ACFs obtained under the temperature of 900 °C and time of 90 min exhibited highest SBET and Vtotal, which were more than 1800 m2/g and 0.7 mL/g, respectively. Meanwhile, more graphic carbon on the surface of ACFs were destroyed with prolonging activation time, resulting in the oxygen-containing functional groups formed during activation process with CO2. Due to the abundant pores and surface functional groups, the ACFs exhibited excellent adsorption capacity of chromium and would be an alternative material for industrial adsorption utilization.

Abstract 13596: Identifying the Most Important Ecg Predictors of Reduced Ejection Fraction in Patients With Suspected Acute Coronary Syndrome

Background: Non-invasive screening tools of cardiac function can play a significant role in the initial triage of patients with suspected acute coronary syndrome. Numerous ECG features have been previously linked with cardiac contractility in the general population. We sought to identify ECG features that are most predictive for real-time screening of reduced left ventricular ejection fraction (LVEF) in the acute care setting. Methods: We performed a secondary analysis of a prospective, observational cohort study of patients evaluated for suspected acute coronary syndrome. The parent study recruited consecutive patients evaluated at the emergency department of three UPMC-affiliated tertiary care hospitals. We included consecutive patients in whom an echocardiogram was performed during indexed encounter. Baseline ECGs were preprocessed using manufacturer specific algorithms. We evaluated 554 automated 12-lead ECG features in multivariate linear regression for predicting LVEF. We then used regression trees to identify the most important predictive ECG features. Results: Our final sample included 297 patients (aged 63 ± 15, 45% females). The mean LVEF was 57% ± 13 (IQR 50%-65%). In multivariate analysis, depolarization dispersion in the horizontal plane; global repolarization dispersion; and abnormal temporal indices in inferolateral leads were all independent predictors of LVEF (R 2 = 0.452, F = 6.679, p &lt; 0.001). Horizontal QRS axis deviation and prolonged ventricular activation (VAT) time in left ventricular apex were the most important determinants of reduced LVEF (Figure), while global QRS duration was of less importance. Conclusions: Poor R wave progression in precordial leads with dominant QS pattern in V3 is the most predictive feature of reduced LVEF in suspected ACS. This feature constitutes a simple visual marker to aid clinicians in identifying those with impaired cardiac function.

Regional repolarization shortening is more arrhythmogenic than regional conduction slowing in an ex vivo porcine experimental model

Ventricular fibrillation (VF) is a major cause of sudden cardiac death. In patients without apparent structural heart disease, J-point elevation and J waves are often associated with an increased risk to VF. The mechanisms underlying these ECG patterns and the associated arrhythmogenesis are still debated. To investigate the respective role of conduction and repolarization heterogeneities in the emergence of J-waves and in the vulnerability to VF. Epi- and endocardial optical mapping experiments were performed in porcine right ventricular (RV) wedge preparations ( n = 26). Both right coronary and left anterior descending (LAD) arteries were perfused separately with Tyrode, followed by addition of either pinacidil (PINA; 20 μM, n = 14) or flecainide (FLECA; 2 μM, n = 12) in the LAD only. RV action potentials (AP) properties were assessed at 1 to 4 Hz stimulation frequencies, and a bath ECG was recorded to evaluate ST segment changes. Spontaneous or induced arrhythmias were quantified and analyzed to calculate dominant frequencies (DF) and regularity index (RI). Local perfusion of PINA induced strong AP duration and repolarization time (RT) heterogeneity on epi- and endocardial surfaces while regional FLECA perfusion significantly prolonged total activation time and increased RT heterogeneity. Both models were associated with changes in ST segment, but those of conduction heterogeneity were more subtle. They both decreased RI of arrhythmias compared to the baseline (0.53 vs. 0.84 P = 0.02 for PINA; 0.47 vs. 0.76 P = 0.06 for FLECA), and DF were significantly higher for PINA compared to FLECA (9.41 vs. 7.74 P = 0.03). Spontaneous VFs are more frequent with a local perfusion of PINA compared to FLECA (86 vs. 8% P = 0.0001). Regional repolarization shortening and conduction slowing result in specific ECG phenotypes and distinct VF dynamics. In our porcine model, repolarization heterogeneity is associated with a higher risk to VF.

Identifying the most important ECG predictors of reduced ejection fraction in patients with suspected acute coronary syndrome

BackgroundNon-invasive screening tools of cardiac function can play a significant role in the initial triage of patients with suspected acute coronary syndrome. Numerous ECG features have been previously linked with cardiac contractility in the general population. We sought to identify ECG features that are most predictive for real-time screening of reduced left ventricular ejection fraction (LVEF) in the acute care setting. MethodsWe performed a secondary analysis of a prospective, observational cohort study of patients evaluated for suspected acute coronary syndrome. We included consecutive patients in whom an echocardiogram was performed during indexed encounter. We evaluated 554 automated 12-lead ECG features in multivariate linear regression for predicting LVEF. We then used regression trees to identify the most important predictive ECG features. ResultsOur final sample included 297 patients (aged 63 ± 15, 45% females). The mean LVEF was 57% ± 13 (IQR 50%–65%). In multivariate analysis, depolarization dispersion in the horizontal plane; global repolarization dispersion; and abnormal temporal indices in inferolateral leads were all independent predictors of LVEF (R2 = 0.452, F = 6.679, p < 0.001). Horizontal QRS axis deviation and prolonged ventricular activation time in left ventricular apex were the most important determinants of reduced LVEF, while global QRS duration was of less importance. ConclusionsPoor R wave progression in precordial leads with dominant QS pattern in V3 is the most predictive feature of reduced LVEF in suspected ACS. This feature constitutes a simple visual marker to aid clinicians in identifying those with impaired cardiac function.

The Effects of Rural Electrification on Quality of Life: A Southeast Asian Perspective

Despite the general agreement about the benefits that electrification brings to well-being, few studies have concentrated on the actual effects of electrification on the diverse non-economic dimensions of quality of life (QoL). In a multi-disciplinary and cross-institutional effort, a group of natural and social scientists have studied three electrification schemes (grid extension, centralised hybrid, and solar home systems) in four rural villages in Malaysia, Cambodia, and Myanmar. Using a novel approach with scales on several QoL measures (self-reported QoL and five QoL sub-domains; psychological, physical, social, and economic well-being; occupations; and total active time), this article presents an analysis of the effects of rural electrification on human well-being. With original data surveyed in the villages through a baseline prior to electrification and an endpoint several months after, the effects were examined through suitable statistical methods. Overall, we confirmed a positive effect of electrification in self-reported QoL levels as well as psychological, physical, and social well-being. There was, however, a certain reduction recorded in economic well-being. In the sub-domains of QoL, there were no changes after electrification in satisfaction levels concerning time use, time spent alone, housing, and personal safety, but a positive effect on satisfaction levels was observed in cooking. Finally, in terms of occupation, we observed no changes in the total hours dedicated to work and no prolonged active time on usual activities in the household. The findings provide support to the hypothesis of a positive effect on general QoL from electrification, but also suggest more precisely that, for specific QoL sub-domains, the effect might not necessarily exist, or in fact, may be negative. The article concludes by discussing differences determined by cultural aspects and technological limitations in each of the systems under study.

Effects of plasma-activated water treatment on seed germination and growth of mung bean sprouts

The present work aimed to investigate the effect of plasma-activated water (PAW) on seed germination and seedling growth of mung bean sprouts. Distilled water was exposed to non-thermal plasma for 15, 30, 60, and 90 s to prepare PAW, which was defined as PAW15, PAW30, PAW60, and PAW90, respectively. The germination rate, growth characteristics, total phenolic and flavonoid contents were all maximized when mung bean seeds were treated by PAW15, then followed by a decline over the prolonged plasma activation time (30–90 s). PAW15 caused no remarkably changes in the antioxidant capacity of sprouts as compared to DW (p > 0.05). However, the antioxidant activity of sprouts prepared with PAW30, PAW60, and PAW90 were decreased significantly (p < 0.05) compared with that of sprouts soaked in distilled water. In summary, PAW may be used to improve the production of sprouts, but the process parameters should be optimized for each application.

P99 Rapid ventricular stimulation induces augmented conduction delay in Brugada syndrome patients

Abstract Background The exact mechanism for Brugada Syndrome (BrS) is still not clear. There are two main physiologic hypotheses that have been suggested: the repolarization and the depolarization disorder models. Right ventricular (RV) activation delay was verified by echocardiography, conduction time in an explanted heart or in computer simulation. Verification of prolonged longitudinal activation time in human RV of only 5 patients of type-1 BrS and 5 controls was reported in 2008. Methods Bidirectional longitudinal activation times were assessed between RV outflow tract (RVot) and RV-apex (RVa) by stimulating and mapping RV endocardium in BrS patients. Conduction velocity was calculated considering ventricle size and distance between catheters. Results The studies were performed in controls (n = 18) and BrS patients (n = 6). There was no statistical difference in RP interval and QRS duration (PR 146 ± 21.7 vs 167 ± 45.2 ms, p = 0.325; QRS 102 ± 28.2 vs 122 ± 32.2 ms, p = 0.163). There was no difference of longitudinal activation time on stimulation at 500 ms (RVa to RVot: 63 ± 14.3 versus 80 ± 34.2 ms, p = 0.290; RVot to RVa: 50 ± 12.2 versus 76 ± 35.1 ms, p = 0.122). The BrS patients had longer longitudinal activation time on stimulation at 400 ms (RVa to RVot: 61 ± 15.2 versus 87 ± 28.7 ms, p = 0.009; RVot to RVa: 52 ± 11.1 versus 76 ± 35.3 ms, p = 0.029). The difference was not significant when isoproterenol was infused. Conclusions BrS patients display bidirectional longitudinal conduction delay when rapid stimulation. These findings support that BrS might be partly attributable to depolarization abnormality.

The Reversal Effect of Sigma-1 Receptor (S1R) Agonist, SA4503, on Atrial Fibrillation After Depression and Its Underlying Mechanism.

AimSigma-1 receptors have been investigated and shown to play a protective role in both depression and cardiovascular disease. SA4503, known as a σ1 receptor agonist, regulates cardiac calcium and potassium channels in rat models of depression. However, it remains unknown whether SA4503 can alleviate myocardial inflammation or conduction junctions in the atrium after exposure to chronic mild stress.Methods and ResultsSprague-Dawley male rats received 28-day treatment with SA4503, simultaneously with chronic mild stress. Behavior measurements were assessed after the daily doses. Additionally, a multielectrode array assessment, electrophysiological study, immunohistochemistry analysis, histological analysis, and Western blot analysis were performed. Depression rats’ hearts showed abnormal electrical activity, including disordered excitation propagation and prolonged total activation time (TAT). In addition, atrial arrhythmias (AAs), induced by burst stimulation, showed higher incidence and longer duration in the depression group compared to the control group. These changes were related to reduced conduction junctions and enhanced spatial heterogeneity. Importantly, depressed rat hearts showed greater expression of inflammatory factors (TGF-α, IL-6, and TGF-β), more collagen distribution in the extracellular matrix, and lower expression of gap junction proteins (CX40 and CX43). Furthermore, SA4503 partially mitigated the above indices in the depression group (P < 0.01 for all groups).ConclusionThese findings show the effects of the σ1R agonist SA4503; it alleviates atrial myocardial inflammation and conduction junctions after chronic mild stress. SA4503 may be the promising pharmacological agent to treat depression-related AAs by increasing conduction function, improving the expression of connexin 40 and 43, and reducing cardiac myocardial inflammation.

Methane to Methanol: Structure-Activity Relationships for Cu-CHA.

Cu-exchanged zeolites possess active sites that are able to cleave the C-H bond of methane at temperatures ≤200 °C, enabling its selective partial oxidation to methanol. Herein we explore this process over Cu-SSZ-13 materials. We combine activity tests and X-ray absorption spectroscopy (XAS) to thoroughly investigate the influence of reaction parameters and material elemental composition on the productivity and Cu speciation during the key process steps. We find that the CuII moieties responsible for the conversion are formed in the presence of O2 and that high temperature together with prolonged activation time increases the population of such active sites. We evidence a linear correlation between the reducibility of the materials and their methanol productivity. By optimizing the process conditions and material composition, we are able to reach a methanol productivity as high as 0.2 mol CH3OH/mol Cu (125 μmol/g), the highest value reported to date for Cu-SSZ-13. Our results clearly demonstrate that high populations of 2Al Z2CuII sites in 6r, favored at low values of both Si:Al and Cu:Al ratios, inhibit the material performance by being inactive for the conversion. Z[CuIIOH] complexes, although shown to be inactive, are identified as the precursors to the methane-converting active sites. By critical examination of the reported catalytic and spectroscopic evidence, we propose different possible routes for active-site formation.

Catalytic ozonation for low-temperature NOX (x = 1, 2) removal with [rad]OH radicals over Cu doped Ce0.90Co0.10O2 − δ catalysts and mechanism analysis

A series of Ce0.90Co0.10O2−δ and Ce0.90−xCuxCo0.10O2−δ (x=0.03, 0.07 and 0.10) catalysts synthesized by an alkaline hydrothermal method were utilized as ozonation catalysts for the NOX (x=1, 2) removal at low temperatures. A novel catalyst-duct separation apparatus for denitrification by catalytic ozonation was developed by our group. Ce0.83Cu0.07Co0.10O2−δ exhibits the highest catalytic activity (91.5% removal at 120°C), whereas Ce0.80Cu0.10Co0.10O2−δ presents the lowest (74.1% removal at 120°C). Only NO3− is detected in the tail solutions. The catalytic performance presents a positive relationship with the corresponding OH concentration. OH radical can be “transferred” from catalyst surface to the duct, prolonging activation time through its own reproduction reaction. The surface –OH activation, not the surface –OH density determines the OH concentration in the present method. Ce0.83Cu0.07Co0.10O2−δ contains a large number of high-activation bridging –OH, whereas the bridging –OH is absent in Ce0.80Cu0.10Co0.10O2−δ. Therefore, Ce0.83Cu0.07Co0.10O2−δ shows much higher activation for promoting the formation of OH than Ce0.80Cu0.10Co0.10O2−δ.

Preparation of High Value Added Activated Carbons from Corncob for Electric Double Layer Capacitors

In this study, corncob-based activated carbons (ACs) were prepared by carbon dioxide (CO2) activation and their use as electrodes in the electrochemical double layer capacitor (EDLC) performed successfully. The effect of activation time (1-7 h) on the surface area and pore structure was detected by nitrogen adsorption-desorption isotherm at 77 K. The electrochemical properties of these corncob-based ACs were evaluated by using cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) studies. The results showed that the surface area increased to the maximum of 757 m(2) g(-1) with the prolonged activation time. However, when the current density was 50 mA g(-1), the specific capacitance reached to the maximum of 178 F g(-1) in 6 mol L-1 KOH solution when the activation time was 5 h. The capacitance was still up to 157 F g(-1) when increasing the current density to 1000 mA g(-1), indicating a high-rate charge-discharge performance. Furthermore, compared with other reported biomass based ACs, corncob-base ACs showed significantly higher surface specific capacitance (SSC) which means the accessibility and efficient utilization of surface area of these ACs.

Simultaneous Non-Invasive Epicardial and Endocardial Mapping in Patients With Brugada Syndrome: New Insights Into Arrhythmia Mechanisms.

BackgroundThe underlying mechanisms of Brugada syndrome (BrS) are not completely understood. Recent studies provided evidence that the electrophysiological substrate, leading to electrocardiogram abnormalities and/or ventricular arrhythmias, is located in the right ventricular outflow tract (RVOT). The purpose of this study was to examine abnormalities of epicardial and endocardial local unipolar electrograms by simultaneous noninvasive mapping in patients with BrS.Methods and ResultsLocal epicardial and endocardial unipolar electrograms were analyzed using a novel noninvasive epi‐ and endocardial electrophysiology system (NEEES) in 12 patients with BrS and 6 with right bundle branch block for comparison. Fifteen normal subjects composed the control group. Observed depolarization abnormalities included fragmented electrograms in the anatomical area of RVOT endocardially and epicardially, significantly prolonged activation time in the RVOT endocardium (65±20 vs 38±13 ms in controls; P=0.008), prolongation of the activation‐recovery interval in the RVOT epicardium (281±34 vs 247±26 ms in controls; P=0.002). Repolarization abnormalities included a larger area of ST‐segment elevation >2 mV and T‐wave inversions. Negative voltage gradient (−2.5 to −6.0 mV) between epicardium and endocardium of the RVOT was observed in 8 of 12 BrS patients, not present in patients with right bundle branch block or in controls.ConclusionsAbnormalities of epicardial and endocardial electrograms associated with depolarization and repolarization properties were found using NEEES exclusively in the RVOT of BrS patients. These findings support both, depolarization and repolarization abnormalities, being operative at the same time in patients with BrS.

Proarrhythmic remodelling of the right ventricle in a porcine model of repaired tetralogy of Fallot

ObjectiveThe growing adult population with surgically corrected tetralogy of Fallot (TOF) is at risk of arrhythmias and sudden cardiac death. We sought to investigate the contribution of right ventricular (RV)...

Patterns of left atrial activation and evaluation of atrial dyssynchrony in patients with atrial fibrillation and normal controls: Factors beyond the left atrial dimensions

Left atrial (LA) remodeling causing slower and asynchronous conduction is crucial for the maintenance of atrial fibrillation (AF). We propose a simple and quick method to evaluate the LA asynchrony. One hundred thirty patients with AF (AF group) and 70 patients without a history of AF (controls) were examined prospectively using pulsed-wave tissue Doppler imaging. The time intervals from the onset of the P wave to the onset of the A' wave (P-A' intervals) were measured at 4 sites at the mitral annulus: septal, lateral, anterior, and posterior. To assess the LA asynchrony, the differences between the longest and the shortest P-A' interval as well as the standard deviation of all 4 P-A' intervals were calculated. Both groups were matched for the baseline characteristics. The AF group had longer differences between the longest and the shortest P-A' than did controls (37 ± 16 ms vs 28 ± 13 ms; P = .0001). The standard deviation of all 4 P-A' intervals was also higher in the AF group (17 ± 7 ms vs 13 ± 5 ms; P = .0001). Furthermore, distinct patterns of LA activation were observed with most patients with AF showing upward LA activation (86.5%) whereas normal controls were showing downward LA activation (65.5%). Receiver operating characteristic analysis revealed that P-A' anterior successfully discriminated patients with AF from controls (area under the curve 0.85; P < .0001). Furthermore, P-A' anterior > 55 ms discriminated between patients with AF and controls with a sensitivity of 85% a specificity of 81%, a positive predictive value of 0.898, and a negative predictive value of 0.707. Patients with AF showed greater LA asynchrony in pulsed-wave tissue Doppler imaging, upward LA activation, and a prolonged activation time at the anterior mitral annulus. Prolongation of P-A' anterior discriminated between patients with AF and controls with high sensitivity and specificity.