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Workover of natural gas wells in deep carbonate gas reservoirs (DCRs) is facing multiple challenges such as fluid leakage, high temperature, and hydrogen sulfide (H2S) gas kick. Hence, well‐killing fluids with satisfactory plugging ability, high‐temperature tolerance, and anti‐H2S ability are necessary. In this study, we developed a multifunctional anti‐hydrogen sulfide fuzzy‐ball kill fluid (AFKF) for preventing sour gas kicks in DCRs. The performance of the AFKF was optimized and analyzed via experiments and verified through a case study application. The results showed that the fuzzy‐ball structures in the AFKFs demonstrated good stability under extreme H2S aging. The rate of change of certain critical rheological parameters such as apparent viscosity, dynamic plastic ratio, and density of AFKFs before and after hot rolling were no more than 5%. After plugging the fractures with the AFKFs at temperatures between 110°C and 150°C, the inlet driving pressure of the fractures increased from 20.73°C to 21.07 MPa, and no fluid loss was observed at the core outlet after a secondary displacement of formation water. The permeability recovery rate was greater than 90%. Application of AFKF in well DW‐2 showed that the shut‐in pressure rose to 24.6 MPa with no trace of H2S gas at the wellhead after 4 days. The investigation of the H2S mitigation mechanisms revealed that the plugging of the seepage channels by AFKFs forms interconnected bonds that improve the mechanical properties of the reservoir. Additionally, AFKFs absorb H2S gases by protonation and dissociation reactions which convert the hazardous gas into an aqueous solution of sulfide ions (S2−). The proposed AFKF has proven to be effective means of mitigating H2S in DCRs, and minimize the negative impacts of environmental polution, health risks, and equipment corrosion. [ABSTRACT FROM AUTHOR]

Background: The effects of epicardial connections (ECs) involving pulmonary veins (PVs) in atrial fibrillation (AF) ablation have been revealed recently. However, no systematic approaches to identify and ablate the ECs were established. Methods: Patients with AF undergoing radiofrequency (RF) catheter ablation were retrospectively analyzed. ECs were identified when (1) PV isolation (PVI) cannot be achieved after first‐pass isolation; (2) PVI was still absent although the conduction gap was detected and ablated; (3) the earliest activation area (EAA) was revealed located within the PV antrum distant from the initial ablation line using high‐density mapping (HDM) technique; (4) focal ablation at the EAA was effective to achieve PVI. Relevant pacing maneuvers were performed to elucidate ECs' bidirectional conduction. Results: Overall, 36 ECs were identified and ablated in 35/597 (5.86%) patients. Among the 35 patients with ECs, at least one PV insertion of ECs was located at the carina region. The most common pattern was a single breakthrough in 31 (88.6%) patients, followed by multiple breakthroughs in 3 and wide breakthroughs in 1. The median distance from EAA to the initial ablation line was 10.0 mm. The average number of RF energy delivery was 1.75 ± 1.00, and single RF delivery was adequate in 16/36 (44.4%) patients. Continuous potentials were present at the EAA in 9/34 (26.5%) patients. Conclusion: ECs were confirmed and ablated successfully in 5.86% (35/597) AF patients using HDM. PV insertions of ECs were mainly located at the carina region. Continuous potentials might assist in the prediction of ECs. [ABSTRACT FROM AUTHOR]

In the drilling industry, Marsh funnel viscosity is only a dynamic viscosity and cannot characterize actual rheology. Thus, measuring rheology using a Marsh funnel has been drawing considerable attention. In this study, we develop simplified mathematical models for wall shear rate, wall shear stress, and their consistency plots. Moreover, we propose mathematical models for the rheological parameters of Newtonian and non‐Newtonian fluids. We compare the results of the present model with those of a ZNN‐6 viscometer, a computational fluid dynamics (CFD) model, and other analytical models. According to the quantitative analysis results, the average systematic error of the Newtonian, apparent, and plastic viscosities between the present model and the ZNN‐6 viscometer measurements is 1.35%, 8.18%, and 5.42%, respectively. The average systematic error of the yield stress is 21.43%, which is under the controllable scope. Meanwhile, results of the qualitative analysis reveal that the present model for the wall shear rate and stress agrees with the CFD model. Moreover, the flow field inside the Marsh funnel is axisymmetric and has a component velocity in the horizontal direction. In summary, the proposed model is accurate, concise, available for field applications, and beneficial for a successful and safe drilling operation. Furthermore, the CFD approach is a necessary complement to exploring the actual field flow inside the Marsh funnel. [ABSTRACT FROM AUTHOR]

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable myocardium disorder that predominantly affects the ventricle. Little is known about atrial involvement. This study aimed to assess atrial involvement, especially the role of genotype on atrium in ARVC. Methods: The incidence, characterization and predictors of atrial involvement were investigated. Nine known ARVC‐causing genes were screened and the correlation between genotype and atrial involvement was assessed. Results: Right atrium (RA) dilation, left atrium (LA) dilation, and sustained atrial tachyarrhythmias (ATa) were found in 45, 16 and 3 patients, respectively. Gene mutations were identified in 64 (64.0%) patients. Mutation carriers showed more RA dilation than noncarriers (54.7% vs. 27.8%, P = 0.009), and no difference in LA dilation and ATa. Multivariate analysis showed tricuspid regurgitation (OR: 18.867; 95% CI: 1.466‐250.000; P = 0.024) increased the risk of RA dilation and decreased left ventricular ejection fraction (LVEF) (OR: 1.134; 95% CI: 1.002‐1.272; P = 0.031) correlated with LA dilation, whereas genotype showed no significant effect. At a median follow‐up time of 91 months, 7 patients died and 1 patient accepted heart transplantation. New‐onset RA dilation, LA dilation, and sustained ATa were found in 8, 7, and 6 patients, respectively. Atrial involvement was not associated with the long‐term survival. Despite mutation carriers showing more RA dilation, Kaplan‐Meier analysis showed genotype was not associated with atrial involvement. Conclusion: Atrial involvement was common in ARVC. Tricuspid regurgitation and decreased LVEF increased the risk for atrial dilation. Genotype was not associated with atrial involvement. [ABSTRACT FROM AUTHOR]

ABSTRACT Aiming at good thickening ability and temperature resistance in water-based drilling fluid, a novel copolymer viscosifier (SDKP) of sodium 2-acrylamido-2-methylpropane sulfonate (NaAMPS) with N-vinylcaprolactam (NVCL) and cross-linking divinylbenzene (DVB) was prepared by micellar radical polymerization. The composition and molecular structure of optimal SDKP under the optimum reaction conditions was characterized by FT-IR, 1H-NMR, and elemental analysis, and the molecular weight was determined by GPC. Thermal gravimetric analysis showed that the SDKP was even stable when the temperature was not higher than 330 °C. The performance of SDKP as viscosifier for aqueous, brines, and saturated brine bentonite drilling fluid was evaluated before and after aging tests at 230 °C for 16 h. The evaluation results indicated that the SDKP had excellent thickening ability, thermal resistant, and salt tolerance. HTHP rheology test showed that the SDKP containing drilling fluids displayed a thermo-thickening effect in temperature range of 150 to 180 °C, which was beneficial to increase the viscosity and strength of fluids at high temperatures. Shear test showed that the SDKP illustrated a similar shear thinning to xanthan gum. ESEM observations demonstrated that the continuous three-dimensional network was formed in the SDKP aqueous and brines solution, which was probably the main reason for its excellent thickening properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44140. [ABSTRACT FROM AUTHOR]

RFCA for Asymptomatic Persistent AF Background Whether patients with asymptomatic atrial fibrillation (AF) could benefit from radiofrequency catheter ablation (RFCA) remains unclear. This study aimed to compare the outcomes of RFCA between asymptomatic and symptomatic AF. Methods Sixty-six patients with asymptomatic persistent AF who underwent the primary ablation for AF were enrolled; 132 patients with symptomatic persistent AF were matched using propensity score matching. All patients underwent circumferential pulmonary vein isolation in combination with linear ablation using AF termination as the primary procedural endpoint. Results Sinus rhythm (SR) was restored by ablation in 18 (27.3%) patients in the asymptomatic group and 93 (70.5%) in the symptomatic group (P < 0.001). Combined with intravenous infusion of ibutilide (1 mg), the numbers were 45 (68.2%) and 116 (87.8%), respectively (P = 0.001). At 1-year follow-up, SR was present in 23 (34.8%) patients in the asymptomatic group and 78 (59.1%) in the symptomatic group without any antiarrhythmic medication after a single procedure (P = 0.001). Of the 43 patients experiencing recurrence in the asymptomatic group, 16 (37.2%) had recurrent atrial tachycardia (AT)-related symptoms. Multivariate analysis showed that asymptomatic AF was independently associated with AF failed to be terminated by ablation (OR: 7.1; 95% CI: 3.4 to 14.9; P < 0.001) and recurrence (OR: 2.2; 95% CI: 1.1 to 4.4; P = 0.018). Patients with asymptomatic AF showed less improvement in quality of life postablation than those with symptoms. Conclusion Current catheter ablation techniques showed worse outcomes in asymptomatic AF patients than in those with symptoms. Recurrent AT could cause significant symptoms in previously asymptomatic patients. [ABSTRACT FROM AUTHOR]

Background: Intracardiac thrombus has been reported in anecdotal cases of arrhythmogenic right ventricular cardiomyopathy (ARVC). This prospective study aimed to determine the prevalence, risk factors, and prognosis of intracardiac thrombosis in patients with ARVC. Methods: From February 2004 to August 2013, transthoracic echocardiograms and magnetic resonance imagings were performed in 193 patients with ARVC. The prevalence, risk factors, and prognosis of intracardiac thrombosis were investigated. Results: Ten intracardiac thrombi were identified in 8 patients (4.1%), the majority (7/10) of which were found in the right ventricular apex. Multivariate analysis showed that female gender and left ventricular dysfunction were independently associated with increased risk for thrombosis in ARVC. All thrombi were eliminated in 3 weeks after anticoagulation therapy without any complication. During a median follow-up time of 38 months (range 2 to 128), no thromboembolism event or sudden death was observed in patients under anticoagulation therapy; however, in patients without anticoagulation therapy, definite pulmonary thromboembolism occurred in 1 and sudden death due to suspected pulmonary thromboembolism was observed in another. Conclusion: Intracardiac thrombosis may occur in certain patients with ARVC. Female gender and left ventricular dysfunction appeared to be associated with increased risk for thrombosis. Early screening and effective anticoagulation therapy may improve the prognosis. [ABSTRACT FROM AUTHOR]

Long-Term Follow-Up of Linear Ablation for AF Background The long-term outcome of radiofrequency catheter ablation in persistent atrial fibrillation (AF) patients remains controversial due to different procedural strategies. This study aimed to present the clinical outcome of a pure linear ablation approach without circumferential pulmonary vein isolation (CPVI) over an extended (>5 years) follow-up period. Methods From January 2005 to December 2009, 120 consecutive patients (94 men; age, 53.6 ± 10.3 years) with drug-refractory persistent AF that underwent pure linear ablation using AF termination as the desired procedural endpoint were enrolled. Results In the primary procedure, sinus rhythm was restored by ablation in 75 (62.5%) patients, and the remaining 45 patients in whom AF could not be terminated by ablation received electrical cardioversion. During a median follow-up period of 5.1 (range 3.2-7.5) years, sinus rhythm was maintained in 48 (40.0%) patients without any antiarrhythmic drugs after a single procedure. There was a higher long-term success in the patients in whom AF was terminated by ablation than in those requiring cardioversion (49.3 vs. 24.4%; P = 0.007). Conclusion Linear catheter ablation without CPVI is effective for persistent AF. Patients with AF terminated by ablation were associated with a better long-term outcome than those requiring cardioversion [ABSTRACT FROM AUTHOR]

Introduction: This study attempted to delineate the mechanism of organized left atrial tachyarrhythmia (AT) during stepwise linear ablation for atrial fibrillation (AF) using noncontact mapping. Methods and Results: Eighty patients in whom organized ATs developed or induced during stepwise linear ablation for AF were enrolled. Left atrial (LA) activation during ATs was mapped using noncontact mapping. Radiofrequency (RF) energy was delivered to the earliest activation site or narrowest part of the reentrant circuit of ATs. A total of 146 ATs were mapped. Four ATs were characterized as a focal mechanism (cycle length (CL): 225 ± 49 ms). A macroreentrant mechanism was confirmed in the remaining 142 ATs. LA activation time accounted for 100% of CL (205 ± 37 ms). All 142 ATs used the conduction gaps in the basic figure-7 lesion line. There were three types of circuits classified based on the gap location. Type I (n = 68) used gaps at the ridge between left atrial appendage (LAA) and left superior pulmonary vein (LSPV). Type II (n = 50) used gaps on the LA roof. Type III (n = 24) passed through gaps in the mitral isthmus. Ablation at these gaps eliminated 130 ATs. During the follow-up period of 16.2 ± 6.7 months, 82.5% of the 80 patients were in sinus rhythm. Conclusion: The majority of left ATs developed during stepwise linear ablation for AF are macroreentrant through conduction gaps in the figure-7 lesion line, especially at the LAA–LSPV ridge. Noncontact activation mapping can identify these gaps accurately and quickly to target effective catheter ablation. [ABSTRACT FROM AUTHOR]

Aims Methods and results Conclusion To estimate the global burden of myocarditis in the general population from 1990 to 2021.Data on myocarditis were retrieved from the Global Burden of Disease Study 2021. Incidence, deaths, and disability‐adjusted life years (DALYs), along with their age‐standardized rates (ASRs) per 100 000 population, were used to measure the burden of myocarditis. Global, regional, and national analyses were performed for the period between 1990 and 2021. Further sub‐analyses were conducted based on age group, sex, and sociodemographic index (SDI). In 2021, there were 1.3 million (95% uncertainty interval [UI]: 1.1 to 1.6) incident cases, 31.7 thousand (95% UI: 25.5 to 37.1) deaths, and 96.3 thousand (95% UI: 79.6 to 114.8) DALY cases globally. The ASRs of incidence, death, and DALYs significantly decreased from 1990 to 2021, with percentage changes of −3.9% (95% UI: −4.7% to −2.9%), −28.2% (95% UI: −42.2% to −12.5%), and −37.8% (95% UI: −50.5% to −24.3%), respectively. The global burden of myocarditis was higher in males, children, and the elderly. Additionally, the burden of myocarditis varied widely across different SDI regions, with high SDI regions having the highest ASR of incidence, and high‐middle SDI regions having the highest ASRs of deaths and DALYs.Although the ASRs of incidence, deaths, and DALYs significantly decreased from 1990 to 2021, the global number of incidences, deaths, and DALYs increased substantially. Certain populations, including males, children, the elderly, and regions with advanced sociodemographic levels, experienced a heavier burden of myocarditis. [ABSTRACT FROM AUTHOR]

Background: Nonrheumatic valvular heart disease (NRVD) is increasingly becoming a significant public health concern, particularly among older people. In the context of population aging, a detailed report on the epidemiological trends of NRVD is crucial for policymakers to effectively allocate health care resources. This study aimed to explore these trends using data from the GBD (Global Burden of Disease) 2019 study., Methods and Results: We assessed the changing trends of the incidence, mortality, and disability-adjusted life years rates for NRVD by calculating the estimated annual percentage change for each. Additionally, we examined the impact of a region's level of social development on NRVD epidemiological trends and identified key risk factors contributing to NRVD-related deaths. Between 1990 and 2019, the global incidence of NRVD showed a gradual increase, with an estimated annual percentage change of 0.39 (95% CI, 0.30-0.48). The data revealed that women and older people are more likely to develop NRVD. High-sociodemographic index countries exhibited higher age-standardized incidence and mortality rates compared with low- and middle-sociodemographic index countries. The most significant risk factor for NRVD-related mortality was identified as high systolic blood pressure., Conclusions: Over the past 3 decades, the burden of NRVD has intensified, indicating a need for more health care resources to address this issue, which is closely associated with an aging population. Currently, high-sociodemographic index countries report the highest incidences and deaths due to NRVD. However, low- and middle-sociodemographic index countries should also implement measures to manage the rapidly increasing burden of NRVD.

Background: Catheter ablation of premature ventricular contractions (PVCs) that trigger polymorphic ventricular tachycardia (PVT) or ventricular fibrillation has been reported as a novel therapy to reduce the syncope events in patients with catecholaminergic PVT, whereas the long-term ablation outcome and its value in improving exercise-induced ventricular arrhythmias remain unclear., Methods and Results: Fourteen consecutive selected patients with catecholaminergic PVT (mean±SD age, 16±6 years; 43% male patients) treated with maximum β-blockers with no possibility of adding flecainide were prospectively enrolled for catheter ablation. The primary end point was syncope recurrence, and the secondary end point was the reduction of the ventricular arrhythmia score during exercise testing. Twenty-six PVT/ventricular fibrillation-triggering PVCs were identified for ablation. The trigger beats arose from the left ventricle in 50% of the cases and from both ventricles in 36% of the cases. Purkinje potentials were observed at 27% of the targets. After a mean follow-up of 49 months after ablation, 8 (57%) patients were free from syncope recurrence. Ablation of trigger beat significantly reduced the syncope frequency (mean±SD, 4.3±1.6 to 0.5±0.8 events per year; P <0.001) and improved the ventricular arrhythmia scores at the 3-month (5 [range, 3-6] to 1.5 [range, 0-5]; P =0.002) and 12-month (5 [range, 3-6] to 2 [range, 0-5]; P =0.014) follow-ups. The induction of nontriggering PVCs postablation was closely associated with syncope recurrence (hazard ratio, 6.8 [95% CI, 1.3-35.5]; P =0.026)., Conclusions: Catheter ablation of PVT/ventricular fibrillation-triggering PVCs in patients with catecholaminergic PVT who cannot receive flecainide treatment seems to be a safe and feasible adjunctive treatment that may reduce the syncope burden and improve exercise-related ventricular arrhythmias. Induction of nontriggering PVCs after ablation is associated with a higher risk of syncope recurrence.